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postgres/src/backend/access/transam/xact.c
Tom Lane 257cccbe5e Add some marginal tweaks to eliminate memory leakages associated with 
subtransactions.  Trivial subxacts (such as a plpgsql exception block
containing no database access) now demonstrably leak zero bytes.
2004-09-16 20:17:49 +00:00

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/*-------------------------------------------------------------------------
*
* xact.c
* top level transaction system support routines
*
* See src/backend/access/transam/README for more information.
*
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.190 2004/09/16 20:17:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <time.h>
#include <unistd.h>
#include "access/subtrans.h"
#include "access/xact.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "commands/async.h"
#include "commands/tablecmds.h"
#include "commands/trigger.h"
#include "commands/user.h"
#include "executor/spi.h"
#include "libpq/be-fsstubs.h"
#include "miscadmin.h"
#include "storage/fd.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/smgr.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/memutils.h"
#include "utils/portal.h"
#include "utils/relcache.h"
#include "utils/resowner.h"
#include "pgstat.h"
/*
* User-tweakable parameters
*/
int DefaultXactIsoLevel = XACT_READ_COMMITTED;
int XactIsoLevel;
bool DefaultXactReadOnly = false;
bool XactReadOnly;
int CommitDelay = 0; /* precommit delay in microseconds */
int CommitSiblings = 5; /* # concurrent xacts needed to sleep */
/*
* transaction states - transaction state from server perspective
*/
typedef enum TransState
{
TRANS_DEFAULT,
TRANS_START,
TRANS_INPROGRESS,
TRANS_COMMIT,
TRANS_ABORT
} TransState;
/*
* transaction block states - transaction state of client queries
*
* Note: the subtransaction states are used only for non-topmost
* transactions; the others appear only in the topmost transaction.
*/
typedef enum TBlockState
{
/* not-in-transaction-block states */
TBLOCK_DEFAULT, /* idle */
TBLOCK_STARTED, /* running single-query transaction */
/* transaction block states */
TBLOCK_BEGIN, /* starting transaction block */
TBLOCK_INPROGRESS, /* live transaction */
TBLOCK_END, /* COMMIT received */
TBLOCK_ABORT, /* failed xact, awaiting ROLLBACK */
TBLOCK_ABORT_END, /* failed xact, ROLLBACK received */
TBLOCK_ABORT_PENDING, /* live xact, ROLLBACK received */
/* subtransaction states */
TBLOCK_SUBBEGIN, /* starting a subtransaction */
TBLOCK_SUBINPROGRESS, /* live subtransaction */
TBLOCK_SUBEND, /* RELEASE received */
TBLOCK_SUBABORT, /* failed subxact, awaiting ROLLBACK */
TBLOCK_SUBABORT_END, /* failed subxact, ROLLBACK received */
TBLOCK_SUBABORT_PENDING, /* live subxact, ROLLBACK received */
TBLOCK_SUBRESTART, /* live subxact, ROLLBACK TO received */
TBLOCK_SUBABORT_RESTART /* failed subxact, ROLLBACK TO received */
} TBlockState;
/*
* transaction state structure
*/
typedef struct TransactionStateData
{
TransactionId transactionId; /* my XID, or Invalid if none */
SubTransactionId subTransactionId; /* my subxact ID */
char *name; /* savepoint name, if any */
int savepointLevel; /* savepoint level */
TransState state; /* low-level state */
TBlockState blockState; /* high-level state */
int nestingLevel; /* nest depth */
MemoryContext curTransactionContext; /* my xact-lifetime
* context */
ResourceOwner curTransactionOwner; /* my query resources */
List *childXids; /* subcommitted child XIDs */
AclId currentUser; /* subxact start current_user */
bool prevXactReadOnly; /* entry-time xact r/o state */
struct TransactionStateData *parent; /* back link to parent */
} TransactionStateData;
typedef TransactionStateData *TransactionState;
/*
* childXids is currently implemented as an integer List, relying on the
* assumption that TransactionIds are no wider than int. We use these
* macros to provide some isolation in case that changes in the future.
*/
#define lfirst_xid(lc) ((TransactionId) lfirst_int(lc))
#define lappend_xid(list, datum) lappend_int(list, (int) (datum))
/*
* CurrentTransactionState always points to the current transaction state
* block. It will point to TopTransactionStateData when not in a
* transaction at all, or when in a top-level transaction.
*/
static TransactionStateData TopTransactionStateData = {
0, /* transaction id */
0, /* subtransaction id */
NULL, /* savepoint name */
0, /* savepoint level */
TRANS_DEFAULT, /* transaction state */
TBLOCK_DEFAULT, /* transaction block state from the client
* perspective */
0, /* nesting level */
NULL, /* cur transaction context */
NULL, /* cur transaction resource owner */
NIL, /* subcommitted child Xids */
0, /* entry-time current userid */
false, /* entry-time xact r/o state */
NULL /* link to parent state block */
};
static TransactionState CurrentTransactionState = &TopTransactionStateData;
/*
* The subtransaction ID and command ID assignment counters are global
* to a whole transaction, so we do not keep them in the state stack.
*/
static SubTransactionId currentSubTransactionId;
static CommandId currentCommandId;
/*
* These vars hold the value of now(), ie, the transaction start time.
* This does not change as we enter and exit subtransactions, so we don't
* keep it inside the TransactionState stack.
*/
static AbsoluteTime xactStartTime; /* integer part */
static int xactStartTimeUsec; /* microsecond part */
/*
* List of add-on start- and end-of-xact callbacks
*/
typedef struct XactCallbackItem
{
struct XactCallbackItem *next;
XactCallback callback;
void *arg;
} XactCallbackItem;
static XactCallbackItem *Xact_callbacks = NULL;
/*
* List of add-on start- and end-of-subxact callbacks
*/
typedef struct SubXactCallbackItem
{
struct SubXactCallbackItem *next;
SubXactCallback callback;
void *arg;
} SubXactCallbackItem;
static SubXactCallbackItem *SubXact_callbacks = NULL;
static void (*_RollbackFunc) (void *) = NULL;
static void *_RollbackData = NULL;
/* local function prototypes */
static void AssignSubTransactionId(TransactionState s);
static void AbortTransaction(void);
static void AtAbort_Memory(void);
static void AtCleanup_Memory(void);
static void AtCommit_LocalCache(void);
static void AtCommit_Memory(void);
static void AtStart_Cache(void);
static void AtStart_Memory(void);
static void AtStart_ResourceOwner(void);
static void CallXactCallbacks(XactEvent event);
static void CallSubXactCallbacks(SubXactEvent event,
SubTransactionId mySubid,
SubTransactionId parentSubid);
static void CleanupTransaction(void);
static void CommitTransaction(void);
static void RecordTransactionAbort(void);
static void StartTransaction(void);
static void RecordSubTransactionCommit(void);
static void StartSubTransaction(void);
static void CommitSubTransaction(void);
static void AbortSubTransaction(void);
static void CleanupSubTransaction(void);
static void PushTransaction(void);
static void PopTransaction(void);
static void AtSubAbort_Memory(void);
static void AtSubCleanup_Memory(void);
static void AtSubCommit_Memory(void);
static void AtSubStart_Memory(void);
static void AtSubStart_ResourceOwner(void);
static void ShowTransactionState(const char *str);
static void ShowTransactionStateRec(TransactionState state);
static const char *BlockStateAsString(TBlockState blockState);
static const char *TransStateAsString(TransState state);
/* ----------------------------------------------------------------
* transaction state accessors
* ----------------------------------------------------------------
*/
/*
* IsTransactionState
*
* This returns true if we are currently running a query
* within an executing transaction.
*/
bool
IsTransactionState(void)
{
TransactionState s = CurrentTransactionState;
switch (s->state)
{
case TRANS_DEFAULT:
return false;
case TRANS_START:
return true;
case TRANS_INPROGRESS:
return true;
case TRANS_COMMIT:
return true;
case TRANS_ABORT:
return true;
}
/*
* Shouldn't get here, but lint is not happy with this...
*/
return false;
}
/*
* IsAbortedTransactionBlockState
*
* This returns true if we are currently running a query
* within an aborted transaction block.
*/
bool
IsAbortedTransactionBlockState(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_ABORT ||
s->blockState == TBLOCK_SUBABORT)
return true;
return false;
}
/*
* GetTopTransactionId
*
* Get the ID of the main transaction, even if we are currently inside
* a subtransaction.
*/
TransactionId
GetTopTransactionId(void)
{
return TopTransactionStateData.transactionId;
}
/*
* GetCurrentTransactionId
*
* We do not assign XIDs to subtransactions until/unless this is called.
* When we do assign an XID to a subtransaction, recursively make sure
* its parent has one as well (this maintains the invariant that a child
* transaction has an XID following its parent's).
*/
TransactionId
GetCurrentTransactionId(void)
{
TransactionState s = CurrentTransactionState;
if (!TransactionIdIsValid(s->transactionId))
AssignSubTransactionId(s);
return s->transactionId;
}
static void
AssignSubTransactionId(TransactionState s)
{
ResourceOwner currentOwner;
Assert(s->parent != NULL);
Assert(s->state == TRANS_INPROGRESS);
if (!TransactionIdIsValid(s->parent->transactionId))
AssignSubTransactionId(s->parent);
/*
* Generate a new Xid and record it in PG_PROC and pg_subtrans.
*
* NB: we must make the subtrans entry BEFORE the Xid appears anywhere
* in shared storage other than PG_PROC; because if there's no room for
* it in PG_PROC, the subtrans entry is needed to ensure that other
* backends see the Xid as "running". See GetNewTransactionId.
*/
s->transactionId = GetNewTransactionId(true);
SubTransSetParent(s->transactionId, s->parent->transactionId);
/*
* Acquire lock on the transaction XID. (We assume this cannot block.)
* We have to be sure that the lock is assigned to the transaction's
* ResourceOwner.
*/
currentOwner = CurrentResourceOwner;
PG_TRY();
{
CurrentResourceOwner = s->curTransactionOwner;
XactLockTableInsert(s->transactionId);
}
PG_CATCH();
{
/* Ensure CurrentResourceOwner is restored on error */
CurrentResourceOwner = currentOwner;
PG_RE_THROW();
}
PG_END_TRY();
CurrentResourceOwner = currentOwner;
}
/*
* GetCurrentTransactionIdIfAny
*
* Unlike GetCurrentTransactionId, this will return InvalidTransactionId
* if we are currently not in a transaction, or in a transaction or
* subtransaction that has not yet assigned itself an XID.
*/
TransactionId
GetCurrentTransactionIdIfAny(void)
{
TransactionState s = CurrentTransactionState;
return s->transactionId;
}
/*
* GetCurrentSubTransactionId
*/
SubTransactionId
GetCurrentSubTransactionId(void)
{
TransactionState s = CurrentTransactionState;
return s->subTransactionId;
}
/*
* GetCurrentCommandId
*/
CommandId
GetCurrentCommandId(void)
{
/* this is global to a transaction, not subtransaction-local */
return currentCommandId;
}
/*
* GetCurrentTransactionStartTime
*/
AbsoluteTime
GetCurrentTransactionStartTime(void)
{
return xactStartTime;
}
/*
* GetCurrentTransactionStartTimeUsec
*/
AbsoluteTime
GetCurrentTransactionStartTimeUsec(int *msec)
{
*msec = xactStartTimeUsec;
return xactStartTime;
}
/*
* GetCurrentTransactionNestLevel
*
* Note: this will return zero when not inside any transaction, one when
* inside a top-level transaction, etc.
*/
int
GetCurrentTransactionNestLevel(void)
{
TransactionState s = CurrentTransactionState;
return s->nestingLevel;
}
/*
* TransactionIdIsCurrentTransactionId
*
* During bootstrap, we cheat and say "it's not my transaction ID" even though
* it is. Along with transam.c's cheat to say that the bootstrap XID is
* already committed, this causes the tqual.c routines to see previously
* inserted tuples as committed, which is what we need during bootstrap.
*/
bool
TransactionIdIsCurrentTransactionId(TransactionId xid)
{
TransactionState s;
if (AMI_OVERRIDE)
{
Assert(xid == BootstrapTransactionId);
return false;
}
/*
* We will return true for the Xid of the current subtransaction, any
* of its subcommitted children, any of its parents, or any of their
* previously subcommitted children. However, a transaction being
* aborted is no longer "current", even though it may still have an
* entry on the state stack.
*/
for (s = CurrentTransactionState; s != NULL; s = s->parent)
{
ListCell *cell;
if (s->state == TRANS_ABORT)
continue;
if (!TransactionIdIsValid(s->transactionId))
continue; /* it can't have any child XIDs either */
if (TransactionIdEquals(xid, s->transactionId))
return true;
foreach(cell, s->childXids)
{
if (TransactionIdEquals(xid, lfirst_xid(cell)))
return true;
}
}
return false;
}
/*
* CommandCounterIncrement
*/
void
CommandCounterIncrement(void)
{
currentCommandId += 1;
if (currentCommandId == FirstCommandId) /* check for overflow */
{
currentCommandId -= 1;
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("cannot have more than 2^32-1 commands in a transaction")));
}
/* Propagate new command ID into static snapshots, if set */
if (SerializableSnapshot)
SerializableSnapshot->curcid = currentCommandId;
if (LatestSnapshot)
LatestSnapshot->curcid = currentCommandId;
/*
* make cache changes visible to me.
*/
AtCommit_LocalCache();
AtStart_Cache();
}
/* ----------------------------------------------------------------
* StartTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtStart_Cache
*/
static void
AtStart_Cache(void)
{
AcceptInvalidationMessages();
}
/*
* AtStart_Memory
*/
static void
AtStart_Memory(void)
{
TransactionState s = CurrentTransactionState;
/*
* We shouldn't have a transaction context already.
*/
Assert(TopTransactionContext == NULL);
/*
* Create a toplevel context for the transaction.
*/
TopTransactionContext =
AllocSetContextCreate(TopMemoryContext,
"TopTransactionContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* In a top-level transaction, CurTransactionContext is the same as
* TopTransactionContext.
*/
CurTransactionContext = TopTransactionContext;
s->curTransactionContext = CurTransactionContext;
/* Make the CurTransactionContext active. */
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* AtStart_ResourceOwner
*/
static void
AtStart_ResourceOwner(void)
{
TransactionState s = CurrentTransactionState;
/*
* We shouldn't have a transaction resource owner already.
*/
Assert(TopTransactionResourceOwner == NULL);
/*
* Create a toplevel resource owner for the transaction.
*/
s->curTransactionOwner = ResourceOwnerCreate(NULL, "TopTransaction");
TopTransactionResourceOwner = s->curTransactionOwner;
CurTransactionResourceOwner = s->curTransactionOwner;
CurrentResourceOwner = s->curTransactionOwner;
}
/* ----------------------------------------------------------------
* StartSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubStart_Memory
*/
static void
AtSubStart_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(CurTransactionContext != NULL);
/*
* Create a CurTransactionContext, which will be used to hold data
* that survives subtransaction commit but disappears on
* subtransaction abort. We make it a child of the immediate parent's
* CurTransactionContext.
*/
CurTransactionContext = AllocSetContextCreate(CurTransactionContext,
"CurTransactionContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
s->curTransactionContext = CurTransactionContext;
/* Make the CurTransactionContext active. */
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* AtSubStart_ResourceOwner
*/
static void
AtSubStart_ResourceOwner(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/*
* Create a resource owner for the subtransaction. We make it a child
* of the immediate parent's resource owner.
*/
s->curTransactionOwner =
ResourceOwnerCreate(s->parent->curTransactionOwner,
"SubTransaction");
CurTransactionResourceOwner = s->curTransactionOwner;
CurrentResourceOwner = s->curTransactionOwner;
}
/* ----------------------------------------------------------------
* CommitTransaction stuff
* ----------------------------------------------------------------
*/
/*
* RecordTransactionCommit
*/
void
RecordTransactionCommit(void)
{
int nrels;
RelFileNode *rptr;
int nchildren;
TransactionId *children;
/* Get data needed for commit record */
nrels = smgrGetPendingDeletes(true, &rptr);
nchildren = xactGetCommittedChildren(&children);
/*
* If we made neither any XLOG entries nor any temp-rel updates, and
* have no files to be deleted, we can omit recording the transaction
* commit at all. (This test includes the effects of subtransactions,
* so the presence of committed subxacts need not alone force a
* write.)
*/
if (MyXactMadeXLogEntry || MyXactMadeTempRelUpdate || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
bool madeTCentries;
XLogRecPtr recptr;
/* Tell bufmgr and smgr to prepare for commit */
BufmgrCommit();
START_CRIT_SECTION();
/*
* If our transaction made any transaction-controlled XLOG
* entries, we need to lock out checkpoint start between writing
* our XLOG record and updating pg_clog. Otherwise it is possible
* for the checkpoint to set REDO after the XLOG record but fail
* to flush the pg_clog update to disk, leading to loss of the
* transaction commit if we crash a little later. Slightly klugy
* fix for problem discovered 2004-08-10.
*
* (If it made no transaction-controlled XLOG entries, its XID
* appears nowhere in permanent storage, so no one else will ever
* care if it committed; so it doesn't matter if we lose the
* commit flag.)
*
* Note we only need a shared lock.
*/
madeTCentries = (MyLastRecPtr.xrecoff != 0);
if (madeTCentries)
LWLockAcquire(CheckpointStartLock, LW_SHARED);
/*
* We only need to log the commit in XLOG if the transaction made
* any transaction-controlled XLOG entries or will delete files.
*/
if (madeTCentries || nrels > 0)
{
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_commit xlrec;
xlrec.xtime = time(NULL);
xlrec.nrels = nrels;
xlrec.nsubxacts = nchildren;
rdata[0].buffer = InvalidBuffer;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactCommit;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].buffer = InvalidBuffer;
rdata[1].data = (char *) rptr;
rdata[1].len = nrels * sizeof(RelFileNode);
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].buffer = InvalidBuffer;
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, rdata);
}
else
{
/* Just flush through last record written by me */
recptr = ProcLastRecEnd;
}
/*
* We must flush our XLOG entries to disk if we made any XLOG
* entries, whether in or out of transaction control. For
* example, if we reported a nextval() result to the client, this
* ensures that any XLOG record generated by nextval will hit the
* disk before we report the transaction committed.
*
* Note: if we generated a commit record above, MyXactMadeXLogEntry
* will certainly be set now.
*/
if (MyXactMadeXLogEntry)
{
/*
* Sleep before flush! So we can flush more than one commit
* records per single fsync. (The idea is some other backend
* may do the XLogFlush while we're sleeping. This needs work
* still, because on most Unixen, the minimum select() delay
* is 10msec or more, which is way too long.)
*
* We do not sleep if enableFsync is not turned on, nor if there
* are fewer than CommitSiblings other backends with active
* transactions.
*/
if (CommitDelay > 0 && enableFsync &&
CountActiveBackends() >= CommitSiblings)
pg_usleep(CommitDelay);
XLogFlush(recptr);
}
/*
* We must mark the transaction committed in clog if its XID
* appears either in permanent rels or in local temporary rels. We
* test this by seeing if we made transaction-controlled entries
* *OR* local-rel tuple updates. Note that if we made only the
* latter, we have not emitted an XLOG record for our commit, and
* so in the event of a crash the clog update might be lost. This
* is okay because no one else will ever care whether we
* committed.
*/
if (madeTCentries || MyXactMadeTempRelUpdate)
{
TransactionIdCommit(xid);
/* to avoid race conditions, the parent must commit first */
TransactionIdCommitTree(nchildren, children);
}
/* Unlock checkpoint lock if we acquired it */
if (madeTCentries)
LWLockRelease(CheckpointStartLock);
END_CRIT_SECTION();
}
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
MyXactMadeTempRelUpdate = false;
/* Show myself as out of the transaction in PGPROC array */
MyProc->logRec.xrecoff = 0;
/* And clean up local data */
if (rptr)
pfree(rptr);
if (children)
pfree(children);
}
/*
* AtCommit_LocalCache
*/
static void
AtCommit_LocalCache(void)
{
/*
* Make catalog changes visible to me for the next command.
*/
CommandEndInvalidationMessages();
}
/*
* AtCommit_Memory
*/
static void
AtCommit_Memory(void)
{
/*
* Now that we're "out" of a transaction, have the system allocate
* things in the top memory context instead of per-transaction
* contexts.
*/
MemoryContextSwitchTo(TopMemoryContext);
/*
* Release all transaction-local memory.
*/
Assert(TopTransactionContext != NULL);
MemoryContextDelete(TopTransactionContext);
TopTransactionContext = NULL;
CurTransactionContext = NULL;
CurrentTransactionState->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* CommitSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubCommit_Memory
*/
static void
AtSubCommit_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/* Return to parent transaction level's memory context. */
CurTransactionContext = s->parent->curTransactionContext;
MemoryContextSwitchTo(CurTransactionContext);
/*
* Ordinarily we cannot throw away the child's CurTransactionContext,
* since the data it contains will be needed at upper commit. However,
* if there isn't actually anything in it, we can throw it away. This
* avoids a small memory leak in the common case of "trivial" subxacts.
*/
if (MemoryContextIsEmpty(s->curTransactionContext))
{
MemoryContextDelete(s->curTransactionContext);
s->curTransactionContext = NULL;
}
}
/*
* AtSubCommit_childXids
*
* Pass my own XID and my child XIDs up to my parent as committed children.
*/
static void
AtSubCommit_childXids(void)
{
TransactionState s = CurrentTransactionState;
MemoryContext old_cxt;
Assert(s->parent != NULL);
/*
* We keep the child-XID lists in TopTransactionContext; this avoids
* setting up child-transaction contexts for what might be just a few
* bytes of grandchild XIDs.
*/
old_cxt = MemoryContextSwitchTo(TopTransactionContext);
s->parent->childXids = lappend_xid(s->parent->childXids,
s->transactionId);
if (s->childXids != NIL)
{
s->parent->childXids = list_concat(s->parent->childXids,
s->childXids);
/*
* list_concat doesn't free the list header for the second list;
* do so here to avoid memory leakage (kluge)
*/
pfree(s->childXids);
s->childXids = NIL;
}
MemoryContextSwitchTo(old_cxt);
}
/*
* RecordSubTransactionCommit
*/
static void
RecordSubTransactionCommit(void)
{
/*
* We do not log the subcommit in XLOG; it doesn't matter until the
* top-level transaction commits.
*
* We must mark the subtransaction subcommitted in clog if its XID
* appears either in permanent rels or in local temporary rels. We
* test this by seeing if we made transaction-controlled entries *OR*
* local-rel tuple updates. (The test here actually covers the entire
* transaction tree so far, so it may mark subtransactions that don't
* really need it, but it's probably not worth being tenser. Note that
* if a prior subtransaction dirtied these variables, then
* RecordTransactionCommit will have to do the full pushup anyway...)
*/
if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate)
{
TransactionId xid = GetCurrentTransactionId();
/* XXX does this really need to be a critical section? */
START_CRIT_SECTION();
/* Record subtransaction subcommit */
TransactionIdSubCommit(xid);
END_CRIT_SECTION();
}
}
/* ----------------------------------------------------------------
* AbortTransaction stuff
* ----------------------------------------------------------------
*/
/*
* RecordTransactionAbort
*/
static void
RecordTransactionAbort(void)
{
int nrels;
RelFileNode *rptr;
int nchildren;
TransactionId *children;
/* Get data needed for abort record */
nrels = smgrGetPendingDeletes(false, &rptr);
nchildren = xactGetCommittedChildren(&children);
/*
* If we made neither any transaction-controlled XLOG entries nor any
* temp-rel updates, and are not going to delete any files, we can
* omit recording the transaction abort at all. No one will ever care
* that it aborted. (These tests cover our whole transaction tree.)
*/
if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate || nrels > 0)
{
TransactionId xid = GetCurrentTransactionId();
/*
* Catch the scenario where we aborted partway through
* RecordTransactionCommit ...
*/
if (TransactionIdDidCommit(xid))
elog(PANIC, "cannot abort transaction %u, it was already committed", xid);
START_CRIT_SECTION();
/*
* We only need to log the abort in XLOG if the transaction made
* any transaction-controlled XLOG entries or will delete files.
* (If it made no transaction-controlled XLOG entries, its XID
* appears nowhere in permanent storage, so no one else will ever
* care if it committed.)
*
* We do not flush XLOG to disk unless deleting files, since the
* default assumption after a crash would be that we aborted,
* anyway. For the same reason, we don't need to worry about
* interlocking against checkpoint start.
*/
if (MyLastRecPtr.xrecoff != 0 || nrels > 0)
{
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_abort xlrec;
XLogRecPtr recptr;
xlrec.xtime = time(NULL);
xlrec.nrels = nrels;
xlrec.nsubxacts = nchildren;
rdata[0].buffer = InvalidBuffer;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactAbort;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].buffer = InvalidBuffer;
rdata[1].data = (char *) rptr;
rdata[1].len = nrels * sizeof(RelFileNode);
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].buffer = InvalidBuffer;
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, rdata);
/* Must flush if we are deleting files... */
if (nrels > 0)
XLogFlush(recptr);
}
/*
* Mark the transaction aborted in clog. This is not absolutely
* necessary but we may as well do it while we are here.
*
* The ordering here isn't critical but it seems best to mark the
* parent first. This assures an atomic transition of all the
* subtransactions to aborted state from the point of view of
* concurrent TransactionIdDidAbort calls.
*/
TransactionIdAbort(xid);
TransactionIdAbortTree(nchildren, children);
END_CRIT_SECTION();
}
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
MyXactMadeTempRelUpdate = false;
/* Show myself as out of the transaction in PGPROC array */
MyProc->logRec.xrecoff = 0;
/* And clean up local data */
if (rptr)
pfree(rptr);
if (children)
pfree(children);
}
/*
* AtAbort_Memory
*/
static void
AtAbort_Memory(void)
{
/*
* Make sure we are in a valid context (not a child of
* TopTransactionContext...). Note that it is possible for this code
* to be called when we aren't in a transaction at all; go directly to
* TopMemoryContext in that case.
*/
if (TopTransactionContext != NULL)
{
MemoryContextSwitchTo(TopTransactionContext);
/*
* We do not want to destroy the transaction's global state yet,
* so we can't free any memory here.
*/
}
else
MemoryContextSwitchTo(TopMemoryContext);
}
/*
* AtSubAbort_Memory
*/
static void
AtSubAbort_Memory(void)
{
Assert(TopTransactionContext != NULL);
MemoryContextSwitchTo(TopTransactionContext);
}
/*
* AtSubAbort_childXids
*/
static void
AtSubAbort_childXids(void)
{
TransactionState s = CurrentTransactionState;
/*
* We keep the child-XID lists in TopTransactionContext (see
* AtSubCommit_childXids). This means we'd better free the list
* explicitly at abort to avoid leakage.
*/
list_free(s->childXids);
s->childXids = NIL;
}
/*
* RecordSubTransactionAbort
*/
static void
RecordSubTransactionAbort(void)
{
int nrels;
RelFileNode *rptr;
TransactionId xid = GetCurrentTransactionId();
int nchildren;
TransactionId *children;
/* Get data needed for abort record */
nrels = smgrGetPendingDeletes(false, &rptr);
nchildren = xactGetCommittedChildren(&children);
/*
* If we made neither any transaction-controlled XLOG entries nor any
* temp-rel updates, and are not going to delete any files, we can
* omit recording the transaction abort at all. No one will ever care
* that it aborted. (These tests cover our whole transaction tree,
* and therefore may mark subxacts that don't really need it, but it's
* probably not worth being tenser.)
*
* In this case we needn't worry about marking subcommitted children as
* aborted, because they didn't mark themselves as subcommitted in the
* first place; see the optimization in RecordSubTransactionCommit.
*/
if (MyLastRecPtr.xrecoff != 0 || MyXactMadeTempRelUpdate || nrels > 0)
{
START_CRIT_SECTION();
/*
* We only need to log the abort in XLOG if the transaction made
* any transaction-controlled XLOG entries or will delete files.
*/
if (MyLastRecPtr.xrecoff != 0 || nrels > 0)
{
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_abort xlrec;
XLogRecPtr recptr;
xlrec.xtime = time(NULL);
xlrec.nrels = nrels;
xlrec.nsubxacts = nchildren;
rdata[0].buffer = InvalidBuffer;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactAbort;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].buffer = InvalidBuffer;
rdata[1].data = (char *) rptr;
rdata[1].len = nrels * sizeof(RelFileNode);
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].buffer = InvalidBuffer;
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, rdata);
/* Must flush if we are deleting files... */
if (nrels > 0)
XLogFlush(recptr);
}
/*
* Mark the transaction aborted in clog. This is not absolutely
* necessary but XactLockTableWait makes use of it to avoid waiting
* for already-aborted subtransactions.
*/
TransactionIdAbort(xid);
TransactionIdAbortTree(nchildren, children);
END_CRIT_SECTION();
}
/*
* We can immediately remove failed XIDs from PGPROC's cache of
* running child XIDs. It's easiest to do it here while we have the
* child XID array at hand, even though in the main-transaction case
* the equivalent work happens just after return from
* RecordTransactionAbort.
*/
XidCacheRemoveRunningXids(xid, nchildren, children);
/* And clean up local data */
if (rptr)
pfree(rptr);
if (children)
pfree(children);
}
/* ----------------------------------------------------------------
* CleanupTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtCleanup_Memory
*/
static void
AtCleanup_Memory(void)
{
/*
* Now that we're "out" of a transaction, have the system allocate
* things in the top memory context instead of per-transaction
* contexts.
*/
MemoryContextSwitchTo(TopMemoryContext);
Assert(CurrentTransactionState->parent == NULL);
/*
* Release all transaction-local memory.
*/
if (TopTransactionContext != NULL)
MemoryContextDelete(TopTransactionContext);
TopTransactionContext = NULL;
CurTransactionContext = NULL;
CurrentTransactionState->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* CleanupSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubCleanup_Memory
*/
static void
AtSubCleanup_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/* Make sure we're not in an about-to-be-deleted context */
MemoryContextSwitchTo(s->parent->curTransactionContext);
CurTransactionContext = s->parent->curTransactionContext;
/*
* Delete the subxact local memory contexts. Its CurTransactionContext
* can go too (note this also kills CurTransactionContexts from any
* children of the subxact).
*/
if (s->curTransactionContext)
MemoryContextDelete(s->curTransactionContext);
s->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* interface routines
* ----------------------------------------------------------------
*/
/*
* StartTransaction
*/
static void
StartTransaction(void)
{
TransactionState s;
/*
* Let's just make sure the state stack is empty
*/
s = &TopTransactionStateData;
CurrentTransactionState = s;
/*
* check the current transaction state
*/
if (s->state != TRANS_DEFAULT)
elog(WARNING, "StartTransaction while in %s state",
TransStateAsString(s->state));
/*
* set the current transaction state information appropriately during
* start processing
*/
s->state = TRANS_START;
/*
* Make sure we've freed any old snapshot, and reset xact state
* variables
*/
FreeXactSnapshot();
XactIsoLevel = DefaultXactIsoLevel;
XactReadOnly = DefaultXactReadOnly;
/*
* reinitialize within-transaction counters
*/
s->subTransactionId = TopSubTransactionId;
currentSubTransactionId = TopSubTransactionId;
currentCommandId = FirstCommandId;
/*
* must initialize resource-management stuff first
*/
AtStart_Memory();
AtStart_ResourceOwner();
/*
* generate a new transaction id
*/
s->transactionId = GetNewTransactionId(false);
XactLockTableInsert(s->transactionId);
/*
* set now()
*/
xactStartTime = GetCurrentAbsoluteTimeUsec(&(xactStartTimeUsec));
/*
* initialize current transaction state fields
*/
s->nestingLevel = 1;
s->childXids = NIL;
/*
* You might expect to see "s->currentUser = GetUserId();" here, but
* you won't because it doesn't work during startup; the userid isn't
* set yet during a backend's first transaction start. We only use
* the currentUser field in sub-transaction state structs.
*
* prevXactReadOnly is also valid only in sub-transactions.
*/
/*
* initialize other subsystems for new transaction
*/
AtStart_Inval();
AtStart_Cache();
AfterTriggerBeginXact();
/*
* done with start processing, set current transaction state to "in
* progress"
*/
s->state = TRANS_INPROGRESS;
ShowTransactionState("StartTransaction");
}
/*
* CommitTransaction
*/
static void
CommitTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("CommitTransaction");
/*
* check the current transaction state
*/
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "CommitTransaction while in %s state",
TransStateAsString(s->state));
Assert(s->parent == NULL);
/*
* Tell the trigger manager that this transaction is about to be
* committed. He'll invoke all trigger deferred until XACT before we
* really start on committing the transaction.
*/
AfterTriggerEndXact();
/*
* Similarly, let ON COMMIT management do its thing before we start to
* commit.
*/
PreCommit_on_commit_actions();
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/*
* set the current transaction state information appropriately during
* the abort processing
*/
s->state = TRANS_COMMIT;
/*
* Do pre-commit processing (most of this stuff requires database
* access, and in fact could still cause an error...)
*/
AtCommit_Portals();
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
/* NOTIFY commit must come before lower-level cleanup */
AtCommit_Notify();
/* Update the flat password file if we changed pg_shadow or pg_group */
/* This should be the last step before commit */
AtEOXact_UpdatePasswordFile(true);
/*
* Here is where we really truly commit.
*/
RecordTransactionCommit();
/*
* Let others know about no transaction in progress by me. Note that
* this must be done _before_ releasing locks we hold and _after_
* RecordTransactionCommit.
*
* LWLockAcquire(SInvalLock) is required: UPDATE with xid 0 is blocked by
* xid 1' UPDATE, xid 1 is doing commit while xid 2 gets snapshot - if
* xid 2' GetSnapshotData sees xid 1 as running then it must see xid 0
* as running as well or it will see two tuple versions - one deleted
* by xid 1 and one inserted by xid 0. See notes in GetSnapshotData.
*/
if (MyProc != NULL)
{
/* Lock SInvalLock because that's what GetSnapshotData uses. */
LWLockAcquire(SInvalLock, LW_EXCLUSIVE);
MyProc->xid = InvalidTransactionId;
MyProc->xmin = InvalidTransactionId;
/* Clear the subtransaction-XID cache too while holding the lock */
MyProc->subxids.nxids = 0;
MyProc->subxids.overflowed = false;
LWLockRelease(SInvalLock);
}
/*
* This is all post-commit cleanup. Note that if an error is raised
* here, it's too late to abort the transaction. This should be just
* noncritical resource releasing.
*
* The ordering of operations is not entirely random. The idea is:
* release resources visible to other backends (eg, files, buffer
* pins); then release locks; then release backend-local resources. We
* want to release locks at the point where any backend waiting for us
* will see our transaction as being fully cleaned up.
*
* Resources that can be associated with individual queries are handled
* by the ResourceOwner mechanism. The other calls here are for
* backend-wide state.
*/
CallXactCallbacks(XACT_EVENT_COMMIT);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
true, true);
/*
* Make catalog changes visible to all backends. This has to happen
* after relcache references are dropped (see comments for
* AtEOXact_RelationCache), but before locks are released (if anyone
* is waiting for lock on a relation we've modified, we want them to
* know about the catalog change before they start using the
* relation).
*/
AtEOXact_Inval(true);
/*
* Likewise, dropping of files deleted during the transaction is best done
* after releasing relcache and buffer pins. (This is not strictly
* necessary during commit, since such pins should have been released
* already, but this ordering is definitely critical during abort.)
*/
smgrDoPendingDeletes(true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_LOCKS,
true, true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
true, true);
AtEOXact_GUC(true, false);
AtEOXact_SPI(true);
AtEOXact_on_commit_actions(true);
AtEOXact_Namespace(true);
/* smgrcommit already done */
AtEOXact_Files();
pgstat_count_xact_commit();
CurrentResourceOwner = NULL;
ResourceOwnerDelete(TopTransactionResourceOwner);
s->curTransactionOwner = NULL;
CurTransactionResourceOwner = NULL;
TopTransactionResourceOwner = NULL;
AtCommit_Memory();
s->transactionId = InvalidTransactionId;
s->subTransactionId = InvalidSubTransactionId;
s->nestingLevel = 0;
s->childXids = NIL;
/*
* done with commit processing, set current transaction state back to
* default
*/
s->state = TRANS_DEFAULT;
RESUME_INTERRUPTS();
}
/*
* AbortTransaction
*/
static void
AbortTransaction(void)
{
TransactionState s = CurrentTransactionState;
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/*
* Release any LW locks we might be holding as quickly as possible.
* (Regular locks, however, must be held till we finish aborting.)
* Releasing LW locks is critical since we might try to grab them
* again while cleaning up!
*/
LWLockReleaseAll();
/* Clean up buffer I/O and buffer context locks, too */
AbortBufferIO();
UnlockBuffers();
/*
* Also clean up any open wait for lock, since the lock manager will
* choke if we try to wait for another lock before doing this.
*/
LockWaitCancel();
/*
* check the current transaction state
*/
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "AbortTransaction while in %s state",
TransStateAsString(s->state));
Assert(s->parent == NULL);
/*
* set the current transaction state information appropriately during
* the abort processing
*/
s->state = TRANS_ABORT;
/* Make sure we are in a valid memory context */
AtAbort_Memory();
/*
* Reset user id which might have been changed transiently. We cannot
* use s->currentUser, but must get the session userid from
* miscinit.c.
*
* (Note: it is not necessary to restore session authorization here
* because that can only be changed via GUC, and GUC will take care of
* rolling it back if need be. However, an error within a SECURITY
* DEFINER function could send control here with the wrong current
* userid.)
*/
SetUserId(GetSessionUserId());
/*
* do abort processing
*/
AfterTriggerAbortXact();
AtAbort_Portals();
AtEOXact_LargeObject(false); /* 'false' means it's abort */
AtAbort_Notify();
AtEOXact_UpdatePasswordFile(false);
/* Advertise the fact that we aborted in pg_clog. */
RecordTransactionAbort();
/*
* Let others know about no transaction in progress by me. Note that
* this must be done _before_ releasing locks we hold and _after_
* RecordTransactionAbort.
*/
if (MyProc != NULL)
{
/* Lock SInvalLock because that's what GetSnapshotData uses. */
LWLockAcquire(SInvalLock, LW_EXCLUSIVE);
MyProc->xid = InvalidTransactionId;
MyProc->xmin = InvalidTransactionId;
/* Clear the subtransaction-XID cache too while holding the lock */
MyProc->subxids.nxids = 0;
MyProc->subxids.overflowed = false;
LWLockRelease(SInvalLock);
}
/*
* Post-abort cleanup. See notes in CommitTransaction() concerning
* ordering.
*/
CallXactCallbacks(XACT_EVENT_ABORT);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
false, true);
AtEOXact_Inval(false);
smgrDoPendingDeletes(false);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_LOCKS,
false, true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
false, true);
AtEOXact_GUC(false, false);
AtEOXact_SPI(false);
AtEOXact_on_commit_actions(false);
AtEOXact_Namespace(false);
smgrabort();
AtEOXact_Files();
pgstat_count_xact_rollback();
/*
* State remains TRANS_ABORT until CleanupTransaction().
*/
RESUME_INTERRUPTS();
}
/*
* CleanupTransaction
*/
static void
CleanupTransaction(void)
{
TransactionState s = CurrentTransactionState;
/*
* State should still be TRANS_ABORT from AbortTransaction().
*/
if (s->state != TRANS_ABORT)
elog(FATAL, "CleanupTransaction: unexpected state %s",
TransStateAsString(s->state));
/*
* do abort cleanup processing
*/
AtCleanup_Portals(); /* now safe to release portal memory */
CurrentResourceOwner = NULL; /* and resource owner */
if (TopTransactionResourceOwner)
ResourceOwnerDelete(TopTransactionResourceOwner);
s->curTransactionOwner = NULL;
CurTransactionResourceOwner = NULL;
TopTransactionResourceOwner = NULL;
AtCleanup_Memory(); /* and transaction memory */
s->transactionId = InvalidTransactionId;
s->subTransactionId = InvalidSubTransactionId;
s->nestingLevel = 0;
s->childXids = NIL;
/*
* done with abort processing, set current transaction state back to
* default
*/
s->state = TRANS_DEFAULT;
}
/*
* StartTransactionCommand
*/
void
StartTransactionCommand(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* if we aren't in a transaction block, we just do our usual
* start transaction.
*/
case TBLOCK_DEFAULT:
StartTransaction();
s->blockState = TBLOCK_STARTED;
break;
/*
* We are somewhere in a transaction block or subtransaction
* and about to start a new command. For now we do nothing,
* but someday we may do command-local resource initialization.
* (Note that any needed CommandCounterIncrement was done by
* the previous CommitTransactionCommand.)
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
break;
/*
* Here we are in a failed transaction block (one of
* the commands caused an abort) so we do nothing but remain in
* the abort state. Eventually we will get a ROLLBACK command
* which will get us out of this state. (It is up to other
* code to ensure that no commands other than ROLLBACK will be
* processed in these states.)
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(ERROR, "StartTransactionCommand: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
/*
* We must switch to CurTransactionContext before returning. This is
* already done if we called StartTransaction, otherwise not.
*/
Assert(CurTransactionContext != NULL);
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* CommitTransactionCommand
*/
void
CommitTransactionCommand(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* This shouldn't happen, because it means the previous
* StartTransactionCommand didn't set the STARTED state
* appropriately.
*/
case TBLOCK_DEFAULT:
elog(FATAL, "CommitTransactionCommand: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* If we aren't in a transaction block, just do our usual
* transaction commit, and return to the idle state.
*/
case TBLOCK_STARTED:
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are completing a "BEGIN TRANSACTION" command, so we
* change to the "transaction block in progress" state and
* return. (We assume the BEGIN did nothing to the database,
* so we need no CommandCounterIncrement.)
*/
case TBLOCK_BEGIN:
s->blockState = TBLOCK_INPROGRESS;
break;
/*
* This is the case when we have finished executing a command
* someplace within a transaction block. We increment the
* command counter and return.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
CommandCounterIncrement();
break;
/*
* We are completing a "COMMIT" command. Do it and return to
* the idle state.
*/
case TBLOCK_END:
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here we are in the middle of a transaction block but one of
* the commands caused an abort so we do nothing but remain in
* the abort state. Eventually we will get a ROLLBACK comand.
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/*
* Here we were in an aborted transaction block and we just
* got the ROLLBACK command from the user, so clean up the
* already-aborted transaction and return to the idle state.
*/
case TBLOCK_ABORT_END:
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here we were in a perfectly good transaction block but the
* user told us to ROLLBACK anyway. We have to abort the
* transaction and then clean up.
*/
case TBLOCK_ABORT_PENDING:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We were just issued a SAVEPOINT inside a transaction block.
* Start a subtransaction. (DefineSavepoint already did
* PushTransaction, so as to have someplace to put the
* SUBBEGIN state.)
*/
case TBLOCK_SUBBEGIN:
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
break;
/*
* We were issued a COMMIT or RELEASE command, so we end the
* current subtransaction and return to the parent transaction.
* The parent might be ended too, so repeat till we are all the
* way out or find an INPROGRESS transaction.
*/
case TBLOCK_SUBEND:
do
{
CommitSubTransaction();
s = CurrentTransactionState; /* changed by pop */
} while (s->blockState == TBLOCK_SUBEND);
/* If we had a COMMIT command, finish off the main xact too */
if (s->blockState == TBLOCK_END)
{
Assert(s->parent == NULL);
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
}
else
{
Assert(s->blockState == TBLOCK_INPROGRESS ||
s->blockState == TBLOCK_SUBINPROGRESS);
}
break;
/*
* The current already-failed subtransaction is ending due to a
* ROLLBACK or ROLLBACK TO command, so pop it and recursively
* examine the parent (which could be in any of several states).
*/
case TBLOCK_SUBABORT_END:
CleanupSubTransaction();
CommitTransactionCommand();
break;
/*
* As above, but it's not dead yet, so abort first.
*/
case TBLOCK_SUBABORT_PENDING:
AbortSubTransaction();
CleanupSubTransaction();
CommitTransactionCommand();
break;
/*
* The current subtransaction is the target of a ROLLBACK TO
* command. Abort and pop it, then start a new subtransaction
* with the same name.
*/
case TBLOCK_SUBRESTART:
{
char *name;
int savepointLevel;
/* save name and keep Cleanup from freeing it */
name = s->name;
s->name = NULL;
savepointLevel = s->savepointLevel;
AbortSubTransaction();
CleanupSubTransaction();
DefineSavepoint(NULL);
s = CurrentTransactionState; /* changed by push */
s->name = name;
s->savepointLevel = savepointLevel;
/* This is the same as TBLOCK_SUBBEGIN case */
AssertState(s->blockState == TBLOCK_SUBBEGIN);
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
}
break;
/*
* Same as above, but the subtransaction had already failed,
* so we don't need AbortSubTransaction.
*/
case TBLOCK_SUBABORT_RESTART:
{
char *name;
int savepointLevel;
/* save name and keep Cleanup from freeing it */
name = s->name;
s->name = NULL;
savepointLevel = s->savepointLevel;
CleanupSubTransaction();
DefineSavepoint(NULL);
s = CurrentTransactionState; /* changed by push */
s->name = name;
s->savepointLevel = savepointLevel;
/* This is the same as TBLOCK_SUBBEGIN case */
AssertState(s->blockState == TBLOCK_SUBBEGIN);
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
}
break;
}
}
/*
* AbortCurrentTransaction
*/
void
AbortCurrentTransaction(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* we aren't in a transaction, so we do nothing.
*/
case TBLOCK_DEFAULT:
break;
/*
* if we aren't in a transaction block, we just do the basic
* abort & cleanup transaction.
*/
case TBLOCK_STARTED:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* If we are in TBLOCK_BEGIN it means something screwed up
* right after reading "BEGIN TRANSACTION". We assume that
* the user will interpret the error as meaning the BEGIN
* failed to get him into a transaction block, so we should
* abort and return to idle state.
*/
case TBLOCK_BEGIN:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are somewhere in a transaction block and we've gotten a
* failure, so we abort the transaction and set up the persistent
* ABORT state. We will stay in ABORT until we get a ROLLBACK.
*/
case TBLOCK_INPROGRESS:
AbortTransaction();
s->blockState = TBLOCK_ABORT;
/* CleanupTransaction happens when we exit TBLOCK_ABORT_END */
break;
/*
* Here, we failed while trying to COMMIT. Clean up the
* transaction and return to idle state (we do not want to
* stay in the transaction).
*/
case TBLOCK_END:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here, we are already in an aborted transaction state and
* are waiting for a ROLLBACK, but for some reason we failed
* again! So we just remain in the abort state.
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/*
* We are in a failed transaction and we got the ROLLBACK command.
* We have already aborted, we just need to cleanup and go to
* idle state.
*/
case TBLOCK_ABORT_END:
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are in a live transaction and we got a ROLLBACK command.
* Abort, cleanup, go to idle state.
*/
case TBLOCK_ABORT_PENDING:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We got an error inside a subtransaction. Abort just the
* subtransaction, and go to the persistent SUBABORT state
* until we get ROLLBACK.
*/
case TBLOCK_SUBINPROGRESS:
AbortSubTransaction();
s->blockState = TBLOCK_SUBABORT;
break;
/*
* If we failed while trying to create a subtransaction, clean up
* the broken subtransaction and abort the parent. The same
* applies if we get a failure while ending a subtransaction.
*/
case TBLOCK_SUBBEGIN:
case TBLOCK_SUBEND:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
AbortSubTransaction();
CleanupSubTransaction();
AbortCurrentTransaction();
break;
/*
* Same as above, except the Abort() was already done.
*/
case TBLOCK_SUBABORT_END:
case TBLOCK_SUBABORT_RESTART:
CleanupSubTransaction();
AbortCurrentTransaction();
break;
}
}
/*
* PreventTransactionChain
*
* This routine is to be called by statements that must not run inside
* a transaction block, typically because they have non-rollback-able
* side effects or do internal commits.
*
* If we have already started a transaction block, issue an error; also issue
* an error if we appear to be running inside a user-defined function (which
* could issue more commands and possibly cause a failure after the statement
* completes). Subtransactions are verboten too.
*
* stmtNode: pointer to parameter block for statement; this is used in
* a very klugy way to determine whether we are inside a function.
* stmtType: statement type name for error messages.
*/
void
PreventTransactionChain(void *stmtNode, const char *stmtType)
{
/*
* xact block already started?
*/
if (IsTransactionBlock())
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot run inside a transaction block",
stmtType)));
/*
* subtransaction?
*/
if (IsSubTransaction())
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot run inside a subtransaction",
stmtType)));
/*
* Are we inside a function call? If the statement's parameter block
* was allocated in QueryContext, assume it is an interactive command.
* Otherwise assume it is coming from a function.
*/
if (!MemoryContextContains(QueryContext, stmtNode))
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot be executed from a function", stmtType)));
/* If we got past IsTransactionBlock test, should be in default state */
if (CurrentTransactionState->blockState != TBLOCK_DEFAULT &&
CurrentTransactionState->blockState != TBLOCK_STARTED)
elog(FATAL, "cannot prevent transaction chain");
/* all okay */
}
/*
* RequireTransactionChain
*
* This routine is to be called by statements that must run inside
* a transaction block, because they have no effects that persist past
* transaction end (and so calling them outside a transaction block
* is presumably an error). DECLARE CURSOR is an example.
*
* If we appear to be running inside a user-defined function, we do not
* issue an error, since the function could issue more commands that make
* use of the current statement's results. Likewise subtransactions.
* Thus this is an inverse for PreventTransactionChain.
*
* stmtNode: pointer to parameter block for statement; this is used in
* a very klugy way to determine whether we are inside a function.
* stmtType: statement type name for error messages.
*/
void
RequireTransactionChain(void *stmtNode, const char *stmtType)
{
/*
* xact block already started?
*/
if (IsTransactionBlock())
return;
/*
* subtransaction?
*/
if (IsSubTransaction())
return;
/*
* Are we inside a function call? If the statement's parameter block
* was allocated in QueryContext, assume it is an interactive command.
* Otherwise assume it is coming from a function.
*/
if (!MemoryContextContains(QueryContext, stmtNode))
return;
ereport(ERROR,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s may only be used in transaction blocks",
stmtType)));
}
/*
* IsInTransactionChain
*
* This routine is for statements that need to behave differently inside
* a transaction block than when running as single commands. ANALYZE is
* currently the only example.
*
* stmtNode: pointer to parameter block for statement; this is used in
* a very klugy way to determine whether we are inside a function.
*/
bool
IsInTransactionChain(void *stmtNode)
{
/*
* Return true on same conditions that would make
* PreventTransactionChain error out
*/
if (IsTransactionBlock())
return true;
if (IsSubTransaction())
return true;
if (!MemoryContextContains(QueryContext, stmtNode))
return true;
if (CurrentTransactionState->blockState != TBLOCK_DEFAULT &&
CurrentTransactionState->blockState != TBLOCK_STARTED)
return true;
return false;
}
/*
* Register or deregister callback functions for start- and end-of-xact
* operations.
*
* These functions are intended for use by dynamically loaded modules.
* For built-in modules we generally just hardwire the appropriate calls
* (mainly because it's easier to control the order that way, where needed).
*
* At transaction end, the callback occurs post-commit or post-abort, so the
* callback functions can only do noncritical cleanup.
*/
void
RegisterXactCallback(XactCallback callback, void *arg)
{
XactCallbackItem *item;
item = (XactCallbackItem *)
MemoryContextAlloc(TopMemoryContext, sizeof(XactCallbackItem));
item->callback = callback;
item->arg = arg;
item->next = Xact_callbacks;
Xact_callbacks = item;
}
void
UnregisterXactCallback(XactCallback callback, void *arg)
{
XactCallbackItem *item;
XactCallbackItem *prev;
prev = NULL;
for (item = Xact_callbacks; item; prev = item, item = item->next)
{
if (item->callback == callback && item->arg == arg)
{
if (prev)
prev->next = item->next;
else
Xact_callbacks = item->next;
pfree(item);
break;
}
}
}
static void
CallXactCallbacks(XactEvent event)
{
XactCallbackItem *item;
for (item = Xact_callbacks; item; item = item->next)
(*item->callback) (event, item->arg);
}
/*
* Register or deregister callback functions for start- and end-of-subxact
* operations.
*
* Pretty much same as above, but for subtransaction events.
*
* At subtransaction end, the callback occurs post-subcommit or post-subabort,
* so the callback functions can only do noncritical cleanup. At
* subtransaction start, the callback is called when the subtransaction has
* finished initializing.
*/
void
RegisterSubXactCallback(SubXactCallback callback, void *arg)
{
SubXactCallbackItem *item;
item = (SubXactCallbackItem *)
MemoryContextAlloc(TopMemoryContext, sizeof(SubXactCallbackItem));
item->callback = callback;
item->arg = arg;
item->next = SubXact_callbacks;
SubXact_callbacks = item;
}
void
UnregisterSubXactCallback(SubXactCallback callback, void *arg)
{
SubXactCallbackItem *item;
SubXactCallbackItem *prev;
prev = NULL;
for (item = SubXact_callbacks; item; prev = item, item = item->next)
{
if (item->callback == callback && item->arg == arg)
{
if (prev)
prev->next = item->next;
else
SubXact_callbacks = item->next;
pfree(item);
break;
}
}
}
static void
CallSubXactCallbacks(SubXactEvent event,
SubTransactionId mySubid,
SubTransactionId parentSubid)
{
SubXactCallbackItem *item;
for (item = SubXact_callbacks; item; item = item->next)
(*item->callback) (event, mySubid, parentSubid, item->arg);
}
/* ----------------------------------------------------------------
* transaction block support
* ----------------------------------------------------------------
*/
/*
* BeginTransactionBlock
* This executes a BEGIN command.
*/
void
BeginTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* We are not inside a transaction block, so allow one to
* begin.
*/
case TBLOCK_STARTED:
s->blockState = TBLOCK_BEGIN;
break;
/*
* Already a transaction block in progress.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
ereport(WARNING,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
errmsg("there is already a transaction in progress")));
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "BeginTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* EndTransactionBlock
* This executes a COMMIT command.
*
* Since COMMIT may actually do a ROLLBACK, the result indicates what
* happened: TRUE for COMMIT, FALSE for ROLLBACK.
*
* Note that we don't actually do anything here except change blockState.
* The real work will be done in the upcoming CommitTransactionCommand().
* We do it this way because it's not convenient to change memory context,
* resource owner, etc while executing inside a Portal.
*/
bool
EndTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
bool result = false;
switch (s->blockState)
{
/*
* We are in a transaction block, so tell CommitTransactionCommand
* to COMMIT.
*/
case TBLOCK_INPROGRESS:
s->blockState = TBLOCK_END;
result = true;
break;
/*
* We are in a failed transaction block. Tell
* CommitTransactionCommand it's time to exit the block.
*/
case TBLOCK_ABORT:
s->blockState = TBLOCK_ABORT_END;
break;
/*
* We are in a live subtransaction block. Set up to subcommit
* all open subtransactions and then commit the main transaction.
*/
case TBLOCK_SUBINPROGRESS:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBEND;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
result = true;
break;
/*
* Here we are inside an aborted subtransaction. Treat the
* COMMIT as ROLLBACK: set up to abort everything and exit
* the main transaction.
*/
case TBLOCK_SUBABORT:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBABORT_PENDING;
else if (s->blockState == TBLOCK_SUBABORT)
s->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_ABORT_PENDING;
else if (s->blockState == TBLOCK_ABORT)
s->blockState = TBLOCK_ABORT_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* here, the user issued COMMIT when not inside a transaction.
* Issue a WARNING and go to abort state. The upcoming call
* to CommitTransactionCommand() will then put us back into
* the default state.
*/
case TBLOCK_STARTED:
ereport(WARNING,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
errmsg("there is no transaction in progress")));
s->blockState = TBLOCK_ABORT_PENDING;
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
return result;
}
/*
* UserAbortTransactionBlock
* This executes a ROLLBACK command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
UserAbortTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* We are inside a transaction block and we got a ROLLBACK
* command from the user, so tell CommitTransactionCommand
* to abort and exit the transaction block.
*/
case TBLOCK_INPROGRESS:
s->blockState = TBLOCK_ABORT_PENDING;
break;
/*
* We are inside a failed transaction block and we got a ROLLBACK
* command from the user. Abort processing is already done,
* so CommitTransactionCommand just has to cleanup and go back
* to idle state.
*/
case TBLOCK_ABORT:
s->blockState = TBLOCK_ABORT_END;
break;
/*
* We are inside a subtransaction. Mark everything
* up to top level as exitable.
*/
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBABORT_PENDING;
else if (s->blockState == TBLOCK_SUBABORT)
s->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_ABORT_PENDING;
else if (s->blockState == TBLOCK_ABORT)
s->blockState = TBLOCK_ABORT_END;
else
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* The user issued ABORT when not inside a transaction. Issue
* a WARNING and go to abort state. The upcoming call to
* CommitTransactionCommand() will then put us back into the
* default state.
*/
case TBLOCK_STARTED:
ereport(WARNING,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
errmsg("there is no transaction in progress")));
s->blockState = TBLOCK_ABORT_PENDING;
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* DefineSavepoint
* This executes a SAVEPOINT command.
*/
void
DefineSavepoint(char *name)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
/* Normal subtransaction start */
PushTransaction();
s = CurrentTransactionState; /* changed by push */
/*
* Savepoint names, like the TransactionState block itself,
* live in TopTransactionContext.
*/
if (name)
s->name = MemoryContextStrdup(TopTransactionContext, name);
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "DefineSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* ReleaseSavepoint
* This executes a RELEASE command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
ReleaseSavepoint(List *options)
{
TransactionState s = CurrentTransactionState;
TransactionState target,
xact;
ListCell *cell;
char *name = NULL;
switch (s->blockState)
{
/*
* We can't rollback to a savepoint if there is no savepoint
* defined.
*/
case TBLOCK_INPROGRESS:
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
break;
/*
* We are in a non-aborted subtransaction. This is the only
* valid case.
*/
case TBLOCK_SUBINPROGRESS:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "ReleaseSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
foreach(cell, options)
{
DefElem *elem = lfirst(cell);
if (strcmp(elem->defname, "savepoint_name") == 0)
name = strVal(elem->arg);
}
Assert(PointerIsValid(name));
for (target = s; PointerIsValid(target); target = target->parent)
{
if (PointerIsValid(target->name) && strcmp(target->name, name) == 0)
break;
}
if (!PointerIsValid(target))
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/* disallow crossing savepoint level boundaries */
if (target->savepointLevel != s->savepointLevel)
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/*
* Mark "commit pending" all subtransactions up to the target
* subtransaction. The actual commits will happen when control gets
* to CommitTransactionCommand.
*/
xact = CurrentTransactionState;
for (;;)
{
Assert(xact->blockState == TBLOCK_SUBINPROGRESS);
xact->blockState = TBLOCK_SUBEND;
if (xact == target)
break;
xact = xact->parent;
Assert(PointerIsValid(xact));
}
}
/*
* RollbackToSavepoint
* This executes a ROLLBACK TO <savepoint> command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
RollbackToSavepoint(List *options)
{
TransactionState s = CurrentTransactionState;
TransactionState target,
xact;
ListCell *cell;
char *name = NULL;
switch (s->blockState)
{
/*
* We can't rollback to a savepoint if there is no savepoint
* defined.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_ABORT:
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
break;
/*
* There is at least one savepoint, so proceed.
*/
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
foreach(cell, options)
{
DefElem *elem = lfirst(cell);
if (strcmp(elem->defname, "savepoint_name") == 0)
name = strVal(elem->arg);
}
Assert(PointerIsValid(name));
for (target = s; PointerIsValid(target); target = target->parent)
{
if (PointerIsValid(target->name) && strcmp(target->name, name) == 0)
break;
}
if (!PointerIsValid(target))
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/* disallow crossing savepoint level boundaries */
if (target->savepointLevel != s->savepointLevel)
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/*
* Mark "abort pending" all subtransactions up to the target
* subtransaction. The actual aborts will happen when control gets
* to CommitTransactionCommand.
*/
xact = CurrentTransactionState;
for (;;)
{
if (xact == target)
break;
if (xact->blockState == TBLOCK_SUBINPROGRESS)
xact->blockState = TBLOCK_SUBABORT_PENDING;
else if (xact->blockState == TBLOCK_SUBABORT)
xact->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(xact->blockState));
xact = xact->parent;
Assert(PointerIsValid(xact));
}
/* And mark the target as "restart pending" */
if (xact->blockState == TBLOCK_SUBINPROGRESS)
xact->blockState = TBLOCK_SUBRESTART;
else if (xact->blockState == TBLOCK_SUBABORT)
xact->blockState = TBLOCK_SUBABORT_RESTART;
else
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(xact->blockState));
}
/*
* BeginInternalSubTransaction
* This is the same as DefineSavepoint except it allows TBLOCK_STARTED
* state, and therefore it can safely be used in a function that might
* be called when not inside a BEGIN block. Also, we automatically
* cycle through CommitTransactionCommand/StartTransactionCommand
* instead of expecting the caller to do it.
*/
void
BeginInternalSubTransaction(char *name)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_STARTED:
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
/* Normal subtransaction start */
PushTransaction();
s = CurrentTransactionState; /* changed by push */
/*
* Savepoint names, like the TransactionState block itself,
* live in TopTransactionContext.
*/
if (name)
s->name = MemoryContextStrdup(TopTransactionContext, name);
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "BeginInternalSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
CommitTransactionCommand();
StartTransactionCommand();
}
/*
* ReleaseCurrentSubTransaction
*
* RELEASE (ie, commit) the innermost subtransaction, regardless of its
* savepoint name (if any).
* NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this.
*/
void
ReleaseCurrentSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState != TBLOCK_SUBINPROGRESS)
elog(ERROR, "ReleaseCurrentSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
Assert(s->state == TRANS_INPROGRESS);
MemoryContextSwitchTo(CurTransactionContext);
CommitSubTransaction();
s = CurrentTransactionState; /* changed by pop */
Assert(s->state == TRANS_INPROGRESS);
}
/*
* RollbackAndReleaseCurrentSubTransaction
*
* ROLLBACK and RELEASE (ie, abort) the innermost subtransaction, regardless
* of its savepoint name (if any).
* NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this.
*/
void
RollbackAndReleaseCurrentSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/* Must be in a subtransaction */
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "RollbackAndReleaseCurrentSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
/*
* Abort the current subtransaction, if needed.
*/
if (s->blockState == TBLOCK_SUBINPROGRESS)
AbortSubTransaction();
/* And clean it up, too */
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
AssertState(s->blockState == TBLOCK_SUBINPROGRESS ||
s->blockState == TBLOCK_INPROGRESS ||
s->blockState == TBLOCK_STARTED);
}
/*
* AbortOutOfAnyTransaction
*
* This routine is provided for error recovery purposes. It aborts any
* active transaction or transaction block, leaving the system in a known
* idle state.
*/
void
AbortOutOfAnyTransaction(void)
{
TransactionState s = CurrentTransactionState;
/*
* Get out of any transaction or nested transaction
*/
do
{
switch (s->blockState)
{
case TBLOCK_DEFAULT:
/* Not in a transaction, do nothing */
break;
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_END:
case TBLOCK_ABORT_PENDING:
/* In a transaction, so clean up */
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
case TBLOCK_ABORT:
case TBLOCK_ABORT_END:
/* AbortTransaction already done, still need Cleanup */
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* In a subtransaction, so clean it up and abort parent
* too
*/
case TBLOCK_SUBBEGIN:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBEND:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
AbortSubTransaction();
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
break;
case TBLOCK_SUBABORT:
case TBLOCK_SUBABORT_END:
case TBLOCK_SUBABORT_RESTART:
/* As above, but AbortSubTransaction already done */
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
break;
}
} while (s->blockState != TBLOCK_DEFAULT);
/* Should be out of all subxacts now */
Assert(s->parent == NULL);
}
/*
* IsTransactionBlock --- are we within a transaction block?
*/
bool
IsTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_DEFAULT || s->blockState == TBLOCK_STARTED)
return false;
return true;
}
/*
* IsTransactionOrTransactionBlock --- are we within either a transaction
* or a transaction block? (The backend is only really "idle" when this
* returns false.)
*
* This should match up with IsTransactionBlock and IsTransactionState.
*/
bool
IsTransactionOrTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_DEFAULT)
return false;
return true;
}
/*
* TransactionBlockStatusCode - return status code to send in ReadyForQuery
*/
char
TransactionBlockStatusCode(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
return 'I'; /* idle --- not in transaction */
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_END:
case TBLOCK_SUBEND:
return 'T'; /* in transaction */
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
return 'E'; /* in failed transaction */
}
/* should never get here */
elog(FATAL, "invalid transaction block state: %s",
BlockStateAsString(s->blockState));
return 0; /* keep compiler quiet */
}
/*
* IsSubTransaction
*/
bool
IsSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->nestingLevel >= 2)
return true;
return false;
}
/*
* StartSubTransaction
*
* If you're wondering why this is separate from PushTransaction: it's because
* we can't conveniently do this stuff right inside DefineSavepoint. The
* SAVEPOINT utility command will be executed inside a Portal, and if we
* muck with CurrentMemoryContext or CurrentResourceOwner then exit from
* the Portal will undo those settings. So we make DefineSavepoint just
* push a dummy transaction block, and when control returns to the main
* idle loop, CommitTransactionCommand will be called, and we'll come here
* to finish starting the subtransaction.
*/
static void
StartSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->state != TRANS_DEFAULT)
elog(WARNING, "StartSubTransaction while in %s state",
TransStateAsString(s->state));
s->state = TRANS_START;
/*
* Initialize subsystems for new subtransaction
*
* must initialize resource-management stuff first
*/
AtSubStart_Memory();
AtSubStart_ResourceOwner();
AtSubStart_Inval();
AtSubStart_Notify();
AfterTriggerBeginSubXact();
s->state = TRANS_INPROGRESS;
/*
* Call start-of-subxact callbacks
*/
CallSubXactCallbacks(SUBXACT_EVENT_START_SUB, s->subTransactionId,
s->parent->subTransactionId);
ShowTransactionState("StartSubTransaction");
}
/*
* CommitSubTransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
CommitSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("CommitSubTransaction");
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "CommitSubTransaction while in %s state",
TransStateAsString(s->state));
/* Pre-commit processing goes here -- nothing to do at the moment */
s->state = TRANS_COMMIT;
/* Must CCI to ensure commands of subtransaction are seen as done */
CommandCounterIncrement();
/* Mark subtransaction as subcommitted */
if (TransactionIdIsValid(s->transactionId))
{
RecordSubTransactionCommit();
AtSubCommit_childXids();
}
/* Post-commit cleanup */
AfterTriggerEndSubXact(true);
AtSubCommit_Portals(s->subTransactionId,
s->parent->subTransactionId,
s->parent->curTransactionOwner);
AtEOSubXact_LargeObject(true, s->subTransactionId,
s->parent->subTransactionId);
AtSubCommit_Notify();
AtEOSubXact_UpdatePasswordFile(true, s->subTransactionId,
s->parent->subTransactionId);
CallSubXactCallbacks(SUBXACT_EVENT_COMMIT_SUB, s->subTransactionId,
s->parent->subTransactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
true, false);
AtEOSubXact_RelationCache(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Inval(true);
AtSubCommit_smgr();
/*
* The only lock we actually release here is the subtransaction XID lock.
* The rest just get transferred to the parent resource owner.
*/
CurrentResourceOwner = s->curTransactionOwner;
if (TransactionIdIsValid(s->transactionId))
XactLockTableDelete(s->transactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_LOCKS,
true, false);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
true, false);
AtEOXact_GUC(true, true);
AtEOSubXact_SPI(true, s->subTransactionId);
AtEOSubXact_on_commit_actions(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Namespace(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Files(true, s->subTransactionId,
s->parent->subTransactionId);
/*
* We need to restore the upper transaction's read-only state, in case
* the upper is read-write while the child is read-only; GUC will
* incorrectly think it should leave the child state in place.
*/
XactReadOnly = s->prevXactReadOnly;
CurrentResourceOwner = s->parent->curTransactionOwner;
CurTransactionResourceOwner = s->parent->curTransactionOwner;
ResourceOwnerDelete(s->curTransactionOwner);
s->curTransactionOwner = NULL;
AtSubCommit_Memory();
s->state = TRANS_DEFAULT;
PopTransaction();
}
/*
* AbortSubTransaction
*/
static void
AbortSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("AbortSubTransaction");
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "AbortSubTransaction while in %s state",
TransStateAsString(s->state));
HOLD_INTERRUPTS();
s->state = TRANS_ABORT;
/*
* Release any LW locks we might be holding as quickly as possible.
* (Regular locks, however, must be held till we finish aborting.)
* Releasing LW locks is critical since we might try to grab them
* again while cleaning up!
*
* FIXME This may be incorrect --- Are there some locks we should keep?
* Buffer locks, for example? I don't think so but I'm not sure.
*/
LWLockReleaseAll();
AbortBufferIO();
UnlockBuffers();
LockWaitCancel();
/*
* do abort processing
*/
AtSubAbort_Memory();
/*
* We can skip all this stuff if the subxact failed before creating
* a ResourceOwner...
*/
if (s->curTransactionOwner)
{
AfterTriggerEndSubXact(false);
AtSubAbort_Portals(s->subTransactionId,
s->parent->subTransactionId,
s->parent->curTransactionOwner);
AtEOSubXact_LargeObject(false, s->subTransactionId,
s->parent->subTransactionId);
AtSubAbort_Notify();
AtEOSubXact_UpdatePasswordFile(false, s->subTransactionId,
s->parent->subTransactionId);
/* Advertise the fact that we aborted in pg_clog. */
if (TransactionIdIsValid(s->transactionId))
{
RecordSubTransactionAbort();
AtSubAbort_childXids();
}
/* Post-abort cleanup */
CallSubXactCallbacks(SUBXACT_EVENT_ABORT_SUB, s->subTransactionId,
s->parent->subTransactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
false, false);
AtEOSubXact_RelationCache(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Inval(false);
AtSubAbort_smgr();
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_LOCKS,
false, false);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
false, false);
AtEOXact_GUC(false, true);
AtEOSubXact_SPI(false, s->subTransactionId);
AtEOSubXact_on_commit_actions(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Namespace(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Files(false, s->subTransactionId,
s->parent->subTransactionId);
}
/*
* Reset user id which might have been changed transiently. Here we
* want to restore to the userid that was current at subxact entry.
* (As in AbortTransaction, we need not worry about the session
* userid.)
*
* Must do this after AtEOXact_GUC to handle the case where we entered
* the subxact inside a SECURITY DEFINER function (hence current and
* session userids were different) and then session auth was changed
* inside the subxact. GUC will reset both current and session
* userids to the entry-time session userid. This is right in every
* other scenario so it seems simplest to let GUC do that and fix it
* here.
*/
SetUserId(s->currentUser);
/*
* Restore the upper transaction's read-only state, too. This should
* be redundant with GUC's cleanup but we may as well do it for
* consistency with the commit case.
*/
XactReadOnly = s->prevXactReadOnly;
RESUME_INTERRUPTS();
}
/*
* CleanupSubTransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
CleanupSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("CleanupSubTransaction");
if (s->state != TRANS_ABORT)
elog(WARNING, "CleanupSubTransaction while in %s state",
TransStateAsString(s->state));
AtSubCleanup_Portals(s->subTransactionId);
CurrentResourceOwner = s->parent->curTransactionOwner;
CurTransactionResourceOwner = s->parent->curTransactionOwner;
if (s->curTransactionOwner)
ResourceOwnerDelete(s->curTransactionOwner);
s->curTransactionOwner = NULL;
AtSubCleanup_Memory();
s->state = TRANS_DEFAULT;
PopTransaction();
}
/*
* PushTransaction
* Create transaction state stack entry for a subtransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
PushTransaction(void)
{
TransactionState p = CurrentTransactionState;
TransactionState s;
AclId currentUser;
/*
* At present, GetUserId cannot fail, but let's not assume that. Get
* the ID before entering the critical code sequence.
*/
currentUser = GetUserId();
/*
* We keep subtransaction state nodes in TopTransactionContext.
*/
s = (TransactionState)
MemoryContextAllocZero(TopTransactionContext,
sizeof(TransactionStateData));
/*
* Assign a subtransaction ID, watching out for counter wraparound.
*/
currentSubTransactionId += 1;
if (currentSubTransactionId == InvalidSubTransactionId)
{
currentSubTransactionId -= 1;
pfree(s);
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("cannot have more than 2^32-1 subtransactions in a transaction")));
}
/*
* We can now stack a minimally valid subtransaction without fear of
* failure.
*/
s->transactionId = InvalidTransactionId; /* until assigned */
s->subTransactionId = currentSubTransactionId;
s->parent = p;
s->nestingLevel = p->nestingLevel + 1;
s->savepointLevel = p->savepointLevel;
s->state = TRANS_DEFAULT;
s->blockState = TBLOCK_SUBBEGIN;
s->currentUser = currentUser;
s->prevXactReadOnly = XactReadOnly;
CurrentTransactionState = s;
/*
* AbortSubTransaction and CleanupSubTransaction have to be able to
* cope with the subtransaction from here on out; in particular they
* should not assume that it necessarily has a transaction context,
* resource owner, or XID.
*/
}
/*
* PopTransaction
* Pop back to parent transaction state
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
PopTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->state != TRANS_DEFAULT)
elog(WARNING, "PopTransaction while in %s state",
TransStateAsString(s->state));
if (s->parent == NULL)
elog(FATAL, "PopTransaction with no parent");
CurrentTransactionState = s->parent;
/* Let's just make sure CurTransactionContext is good */
CurTransactionContext = s->parent->curTransactionContext;
MemoryContextSwitchTo(CurTransactionContext);
/* Ditto for ResourceOwner links */
CurTransactionResourceOwner = s->parent->curTransactionOwner;
CurrentResourceOwner = s->parent->curTransactionOwner;
/* Free the old child structure */
if (s->name)
pfree(s->name);
pfree(s);
}
/*
* ShowTransactionState
* Debug support
*/
static void
ShowTransactionState(const char *str)
{
/* skip work if message will definitely not be printed */
if (log_min_messages <= DEBUG2 || client_min_messages <= DEBUG2)
{
elog(DEBUG2, "%s", str);
ShowTransactionStateRec(CurrentTransactionState);
}
}
/*
* ShowTransactionStateRec
* Recursive subroutine for ShowTransactionState
*/
static void
ShowTransactionStateRec(TransactionState s)
{
if (s->parent)
ShowTransactionStateRec(s->parent);
/* use ereport to suppress computation if msg will not be printed */
ereport(DEBUG2,
(errmsg_internal("name: %s; blockState: %13s; state: %7s, xid/subid/cid: %u/%u/%u, nestlvl: %d, children: %s",
PointerIsValid(s->name) ? s->name : "unnamed",
BlockStateAsString(s->blockState),
TransStateAsString(s->state),
(unsigned int) s->transactionId,
(unsigned int) s->subTransactionId,
(unsigned int) currentCommandId,
s->nestingLevel,
nodeToString(s->childXids))));
}
/*
* BlockStateAsString
* Debug support
*/
static const char *
BlockStateAsString(TBlockState blockState)
{
switch (blockState)
{
case TBLOCK_DEFAULT:
return "DEFAULT";
case TBLOCK_STARTED:
return "STARTED";
case TBLOCK_BEGIN:
return "BEGIN";
case TBLOCK_INPROGRESS:
return "INPROGRESS";
case TBLOCK_END:
return "END";
case TBLOCK_ABORT:
return "ABORT";
case TBLOCK_ABORT_END:
return "ABORT END";
case TBLOCK_ABORT_PENDING:
return "ABORT PEND";
case TBLOCK_SUBBEGIN:
return "SUB BEGIN";
case TBLOCK_SUBINPROGRESS:
return "SUB INPROGRS";
case TBLOCK_SUBEND:
return "SUB END";
case TBLOCK_SUBABORT:
return "SUB ABORT";
case TBLOCK_SUBABORT_END:
return "SUB ABORT END";
case TBLOCK_SUBABORT_PENDING:
return "SUB ABRT PEND";
case TBLOCK_SUBRESTART:
return "SUB RESTART";
case TBLOCK_SUBABORT_RESTART:
return "SUB AB RESTRT";
}
return "UNRECOGNIZED";
}
/*
* TransStateAsString
* Debug support
*/
static const char *
TransStateAsString(TransState state)
{
switch (state)
{
case TRANS_DEFAULT:
return "DEFAULT";
case TRANS_START:
return "START";
case TRANS_COMMIT:
return "COMMIT";
case TRANS_ABORT:
return "ABORT";
case TRANS_INPROGRESS:
return "INPROGR";
}
return "UNRECOGNIZED";
}
/*
* xactGetCommittedChildren
*
* Gets the list of committed children of the current transaction. The return
* value is the number of child transactions. *children is set to point to a
* palloc'd array of TransactionIds. If there are no subxacts, *children is
* set to NULL.
*/
int
xactGetCommittedChildren(TransactionId **ptr)
{
TransactionState s = CurrentTransactionState;
int nchildren;
TransactionId *children;
ListCell *p;
nchildren = list_length(s->childXids);
if (nchildren == 0)
{
*ptr = NULL;
return 0;
}
children = (TransactionId *) palloc(nchildren * sizeof(TransactionId));
*ptr = children;
foreach(p, s->childXids)
{
TransactionId child = lfirst_xid(p);
*children++ = child;
}
return nchildren;
}
/*
* XLOG support routines
*/
void
xact_redo(XLogRecPtr lsn, XLogRecord *record)
{
uint8 info = record->xl_info & ~XLR_INFO_MASK;
if (info == XLOG_XACT_COMMIT)
{
xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record);
TransactionId *sub_xids;
TransactionId max_xid;
int i;
TransactionIdCommit(record->xl_xid);
/* Mark committed subtransactions as committed */
sub_xids = (TransactionId *) &(xlrec->xnodes[xlrec->nrels]);
TransactionIdCommitTree(xlrec->nsubxacts, sub_xids);
/* Make sure nextXid is beyond any XID mentioned in the record */
max_xid = record->xl_xid;
for (i = 0; i < xlrec->nsubxacts; i++)
{
if (TransactionIdPrecedes(max_xid, sub_xids[i]))
max_xid = sub_xids[i];
}
if (TransactionIdFollowsOrEquals(max_xid,
ShmemVariableCache->nextXid))
{
ShmemVariableCache->nextXid = max_xid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
}
/* Make sure files supposed to be dropped are dropped */
for (i = 0; i < xlrec->nrels; i++)
{
XLogCloseRelation(xlrec->xnodes[i]);
smgrdounlink(smgropen(xlrec->xnodes[i]), false, true);
}
}
else if (info == XLOG_XACT_ABORT)
{
xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record);
TransactionId *sub_xids;
TransactionId max_xid;
int i;
TransactionIdAbort(record->xl_xid);
/* Mark subtransactions as aborted */
sub_xids = (TransactionId *) &(xlrec->xnodes[xlrec->nrels]);
TransactionIdAbortTree(xlrec->nsubxacts, sub_xids);
/* Make sure nextXid is beyond any XID mentioned in the record */
max_xid = record->xl_xid;
for (i = 0; i < xlrec->nsubxacts; i++)
{
if (TransactionIdPrecedes(max_xid, sub_xids[i]))
max_xid = sub_xids[i];
}
if (TransactionIdFollowsOrEquals(max_xid,
ShmemVariableCache->nextXid))
{
ShmemVariableCache->nextXid = max_xid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
}
/* Make sure files supposed to be dropped are dropped */
for (i = 0; i < xlrec->nrels; i++)
{
XLogCloseRelation(xlrec->xnodes[i]);
smgrdounlink(smgropen(xlrec->xnodes[i]), false, true);
}
}
else
elog(PANIC, "xact_redo: unknown op code %u", info);
}
void
xact_undo(XLogRecPtr lsn, XLogRecord *record)
{
uint8 info = record->xl_info & ~XLR_INFO_MASK;
if (info == XLOG_XACT_COMMIT) /* shouldn't be called by XLOG */
elog(PANIC, "xact_undo: can't undo committed xaction");
else if (info != XLOG_XACT_ABORT)
elog(PANIC, "xact_redo: unknown op code %u", info);
}
void
xact_desc(char *buf, uint8 xl_info, char *rec)
{
uint8 info = xl_info & ~XLR_INFO_MASK;
int i;
if (info == XLOG_XACT_COMMIT)
{
xl_xact_commit *xlrec = (xl_xact_commit *) rec;
struct tm *tm = localtime(&xlrec->xtime);
sprintf(buf + strlen(buf), "commit: %04u-%02u-%02u %02u:%02u:%02u",
tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
if (xlrec->nrels > 0)
{
sprintf(buf + strlen(buf), "; rels:");
for (i = 0; i < xlrec->nrels; i++)
{
RelFileNode rnode = xlrec->xnodes[i];
sprintf(buf + strlen(buf), " %u/%u/%u",
rnode.spcNode, rnode.dbNode, rnode.relNode);
}
}
if (xlrec->nsubxacts > 0)
{
TransactionId *xacts = (TransactionId *)
&xlrec->xnodes[xlrec->nrels];
sprintf(buf + strlen(buf), "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
sprintf(buf + strlen(buf), " %u", xacts[i]);
}
}
else if (info == XLOG_XACT_ABORT)
{
xl_xact_abort *xlrec = (xl_xact_abort *) rec;
struct tm *tm = localtime(&xlrec->xtime);
sprintf(buf + strlen(buf), "abort: %04u-%02u-%02u %02u:%02u:%02u",
tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
if (xlrec->nrels > 0)
{
sprintf(buf + strlen(buf), "; rels:");
for (i = 0; i < xlrec->nrels; i++)
{
RelFileNode rnode = xlrec->xnodes[i];
sprintf(buf + strlen(buf), " %u/%u/%u",
rnode.spcNode, rnode.dbNode, rnode.relNode);
}
}
if (xlrec->nsubxacts > 0)
{
TransactionId *xacts = (TransactionId *)
&xlrec->xnodes[xlrec->nrels];
sprintf(buf + strlen(buf), "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
sprintf(buf + strlen(buf), " %u", xacts[i]);
}
}
else
strcat(buf, "UNKNOWN");
}
void
XactPushRollback(void (*func) (void *), void *data)
{
#ifdef XLOG_II
if (_RollbackFunc != NULL)
elog(PANIC, "XactPushRollback: already installed");
#endif
_RollbackFunc = func;
_RollbackData = data;
}
void
XactPopRollback(void)
{
_RollbackFunc = NULL;
}
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