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In SQLITE_ENABLE_SETLK_TIMEOUT builds, use blocking locks in place of sleep() calls when opening a read-transaction.

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FossilOrigin-Name: 4c055b7a6e4533e1e571773456226ca7038ce372df3eedbbbcd9a81e8652a6cf
This commit is contained in:
dan 2023-11-28 17:12:42 +00:00
commit 940b23bc3a
4 changed files with 66 additions and 27 deletions
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15
manifest
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@ -1,5 +1,5 @@
C Add\sthe\s--buildonly\sand\s--dryrun\soptions\sto\stestrunner.tcl.
D 2023-11-24T20:14:18.100
C In\sSQLITE_ENABLE_SETLK_TIMEOUT\sbuilds,\suse\sblocking\slocks\sin\splace\sof\ssleep()\scalls\swhen\sopening\sa\sread-transaction.
D 2023-11-28T17:12:42.879
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -712,7 +712,7 @@ F src/os.h 1ff5ae51d339d0e30d8a9d814f4b8f8e448169304d83a7ed9db66a65732f3e63
F src/os_common.h 6c0eb8dd40ef3e12fe585a13e709710267a258e2c8dd1c40b1948a1d14582e06
F src/os_kv.c 4d39e1f1c180b11162c6dc4aa8ad34053873a639bac6baae23272fc03349986a
F src/os_setup.h 6011ad7af5db4e05155f385eb3a9b4470688de6f65d6166b8956e58a3d872107
F src/os_unix.c dc5404b56da7fb13cf272ddb94c3753cf9e82d32a65cba35dbb6aadcb849419c
F src/os_unix.c 97bdcd43315da7aaec9fea2da1ff7c9de458f93dd363e073f2742403a7f2e011
F src/os_win.c 4a50a154aeebc66a1f8fb79c1ff6dd5fe3d005556533361e0d460d41cb6a45a8
F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
F src/pager.c 987ab3a2cd9065d62e9955474470ff733445e2357432a67e3d0f5a8f9313e334
@ -810,7 +810,7 @@ F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf8
F src/vdbevtab.c 2143db7db0ceed69b21422581f434baffc507a08d831565193a7a02882a1b6a7
F src/vtab.c 154725ebecd3bc02f7fbd7ad3974334f73fff76e02a964e828e48a7c5fb7efff
F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
F src/wal.c 69aa3ce60b2862a24cd86bb528e653e2137388ead258ef64db49ec9038807f5f
F src/wal.c e5247a3406531b705b44630e9ccf9ca0e5c74955ef19c06fbb146d765c500c20
F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
F src/where.c 1fdc69ce1333e9bd6d7d3df9fa5af1373a3f5bfdd52108d1dbc0ca85a55f777e
@ -2143,8 +2143,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P f8ea0b58b37f4052ded448e595d6d2992988a33b8ecfe58d68f20532f8cb5a37
R a09b448e8fa45e3193b13a1fe5b499b2
P a0c87ae9d3db914d18e2c8811db0d0ae3ad7b15c63de84fa975efce28bace27e 5fbf3906d272df3eb981f67455eb35f649ad2774cba9fc3f077b28d9bef3f0cb
R a3e95520ff5d52f362b8ffc8bb5b50fd
T +closed 5fbf3906d272df3eb981f67455eb35f649ad2774cba9fc3f077b28d9bef3f0cb
U dan
Z ce0098ca9d7841ef7ea900cfd937f5a5
Z fe1d300d9f65afce84bb98eff88fc681
# Remove this line to create a well-formed Fossil manifest.

2
manifest.uuid
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@ -1 +1 @@
a0c87ae9d3db914d18e2c8811db0d0ae3ad7b15c63de84fa975efce28bace27e
4c055b7a6e4533e1e571773456226ca7038ce372df3eedbbbcd9a81e8652a6cf

13
src/os_unix.c
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@ -4595,7 +4595,20 @@ static int unixLockSharedMemory(unixFile *pDbFd, unixShmNode *pShmNode){
pShmNode->isUnlocked = 1;
rc = SQLITE_READONLY_CANTINIT;
}else{
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/* Do not use a blocking lock here. If the lock cannot be obtained
** immediately, it means some other connection is truncating the
** *-shm file. And after it has done so, it will not release its
** lock, but only downgrade it to a shared lock. So no point in
** blocking here. The call below to obtain the shared DMS lock may
** use a blocking lock. */
int iSaveTimeout = pDbFd->iBusyTimeout;
pDbFd->iBusyTimeout = 0;
#endif
rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1);
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
pDbFd->iBusyTimeout = iSaveTimeout;
#endif
/* The first connection to attach must truncate the -shm file. We
** truncate to 3 bytes (an arbitrary small number, less than the
** -shm header size) rather than 0 as a system debugging aid, to

63
src/wal.c
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@ -2004,6 +2004,19 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
}
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/*
** Attempt to enable blocking locks that block for nMs ms. Return 1 if
** blocking locks are successfully enabled, or 0 otherwise.
*/
static int walEnableBlockingMs(Wal *pWal, int nMs){
int rc = sqlite3OsFileControl(
pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&nMs
);
return (rc==SQLITE_OK);
}
/*
** Attempt to enable blocking locks. Blocking locks are enabled only if (a)
** they are supported by the VFS, and (b) the database handle is configured
@ -2015,11 +2028,7 @@ static int walEnableBlocking(Wal *pWal){
if( pWal->db ){
int tmout = pWal->db->busyTimeout;
if( tmout ){
int rc;
rc = sqlite3OsFileControl(
pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout
);
res = (rc==SQLITE_OK);
res = walEnableBlockingMs(pWal, tmout);
}
}
return res;
@ -2068,20 +2077,10 @@ void sqlite3WalDb(Wal *pWal, sqlite3 *db){
pWal->db = db;
}
/*
** Take an exclusive WRITE lock. Blocking if so configured.
*/
static int walLockWriter(Wal *pWal){
int rc;
walEnableBlocking(pWal);
rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
walDisableBlocking(pWal);
return rc;
}
#else
# define walEnableBlocking(x) 0
# define walDisableBlocking(x)
# define walLockWriter(pWal) walLockExclusive((pWal), WAL_WRITE_LOCK, 1)
# define walEnableBlockingMs(pWal, ms) 0
# define sqlite3WalDb(pWal, db)
#endif /* ifdef SQLITE_ENABLE_SETLK_TIMEOUT */
@ -2682,7 +2681,9 @@ static int walIndexReadHdr(Wal *pWal, int *pChanged){
}
}else{
int bWriteLock = pWal->writeLock;
if( bWriteLock || SQLITE_OK==(rc = walLockWriter(pWal)) ){
if( bWriteLock
|| SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1))
){
pWal->writeLock = 1;
if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
badHdr = walIndexTryHdr(pWal, pChanged);
@ -2690,7 +2691,8 @@ static int walIndexReadHdr(Wal *pWal, int *pChanged){
/* If the wal-index header is still malformed even while holding
** a WRITE lock, it can only mean that the header is corrupted and
** needs to be reconstructed. So run recovery to do exactly that.
*/
** Disable blocking locks first. */
walDisableBlocking(pWal);
rc = walIndexRecover(pWal);
*pChanged = 1;
}
@ -2957,6 +2959,9 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
int i; /* Loop counter */
int rc = SQLITE_OK; /* Return code */
u32 mxFrame; /* Wal frame to lock to */
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
int nBlockTmout = 0;
#endif
assert( pWal->readLock<0 ); /* Not currently locked */
@ -2987,6 +2992,19 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
return SQLITE_PROTOCOL;
}
if( cnt>=10 ) nDelay = (cnt-9)*(cnt-9)*39;
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/* In SQLITE_ENABLE_SETLK_TIMEOUT builds, configure the file-descriptor
** to block for locks for approximately nDelay us. This affects three
** locks: (a) the shared lock taken on the DMS slot in os_unix.c (if
** using os_unix.c), (b) the WRITER lock taken in walIndexReadHdr() if the
** first attempted read fails, and (c) the shared lock taken on the DMS
** slot in os_unix.c. All three of these locks are attempted from within
** the call to walIndexReadHdr() below. */
nBlockTmout = (nDelay+998) / 1000;
if( !useWal && walEnableBlockingMs(pWal, nBlockTmout) ){
nDelay = 1;
}
#endif
sqlite3OsSleep(pWal->pVfs, nDelay);
}
@ -2995,6 +3013,10 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
if( pWal->bShmUnreliable==0 ){
rc = walIndexReadHdr(pWal, pChanged);
}
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
walDisableBlocking(pWal);
if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
#endif
if( rc==SQLITE_BUSY ){
/* If there is not a recovery running in another thread or process
** then convert BUSY errors to WAL_RETRY. If recovery is known to
@ -3109,9 +3131,12 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
return rc==SQLITE_BUSY ? WAL_RETRY : SQLITE_READONLY_CANTINIT;
}
(void)walEnableBlockingMs(pWal, nBlockTmout);
rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
walDisableBlocking(pWal);
if( rc ){
return rc==SQLITE_BUSY ? WAL_RETRY : rc;
assert( (rc&0xFF)!=SQLITE_BUSY||rc==SQLITE_BUSY||rc==SQLITE_BUSY_TIMEOUT );
return (rc&0xFF)==SQLITE_BUSY ? WAL_RETRY : rc;
}
/* Now that the read-lock has been obtained, check that neither the
** value in the aReadMark[] array or the contents of the wal-index