Comment and stylistic changes to the appendvfs.c implementation.
FossilOrigin-Name: 25c3186aa143328157fb506a29802e87099cd14be4fa218230484a3212f20621
This commit is contained in:
drh
parent
67d4bbf6c1
commit
3fee67533e
@ -38,8 +38,8 @@
|
||||
** (5) Otherwise, SQLITE_CANTOPEN is returned.
|
||||
**
|
||||
** To avoid unnecessary complications with the PENDING_BYTE, the size of
|
||||
** the file containing the database is limited to 1GB. (1000013824 bytes)
|
||||
** This VFS will not read or write past the 1GB mark. This restriction
|
||||
** the file containing the database is limited to 1GiB. (1073741824 bytes)
|
||||
** This VFS will not read or write past the 1GiB mark. This restriction
|
||||
** might be lifted in future versions. For now, if you need a larger
|
||||
** database, then keep it in a separate file.
|
||||
**
|
||||
@ -68,14 +68,16 @@ SQLITE_EXTENSION_INIT1
|
||||
** Maximum size of the combined prefix + database + append-mark. This
|
||||
** must be less than 0x40000000 to avoid locking issues on Windows.
|
||||
*/
|
||||
#define APND_MAX_SIZE (65536*15259)
|
||||
#define APND_MAX_SIZE (0x40000000)
|
||||
|
||||
/*
|
||||
** Size of storage page upon which to align appendvfs portion.
|
||||
** Try to align the database to an even multiple of APND_ROUNDUP bytes.
|
||||
*/
|
||||
#ifndef APND_ROUNDUP_BITS
|
||||
#define APND_ROUNDUP_BITS 12
|
||||
#ifndef APND_ROUNDUP
|
||||
#define APND_ROUNDUP 4096
|
||||
#endif
|
||||
#define APND_ALIGN_MASK ((sqlite3_int64)(APND_ROUNDUP-1))
|
||||
#define APND_START_ROUNDUP(fsz) (((fsz)+APND_ALIGN_MASK) & ~APND_ALIGN_MASK)
|
||||
|
||||
/*
|
||||
** Forward declaration of objects used by this utility
|
||||
@ -89,43 +91,45 @@ typedef struct ApndFile ApndFile;
|
||||
#define ORIGVFS(p) ((sqlite3_vfs*)((p)->pAppData))
|
||||
#define ORIGFILE(p) ((sqlite3_file*)(((ApndFile*)(p))+1))
|
||||
|
||||
/* Invariants for an open appendvfs file:
|
||||
* Once an appendvfs file is opened, it will be in one of three states:
|
||||
* State 0: Never written. Underlying file (if any) is unaltered.
|
||||
* State 1: Append mark is persisted, content write is in progress.
|
||||
* State 2: Append mark is persisted, content writes are complete.
|
||||
*
|
||||
* State 0 is persistent in the sense that nothing will have been done
|
||||
* to the underlying file, including any attempt to convert it to an
|
||||
* appendvfs file.
|
||||
*
|
||||
* State 1 is normally transitory. However, if a write operation ends
|
||||
* abnormally (disk full, power loss, process kill, etc.), then State 1
|
||||
* may be persistent on disk with an incomplete content write-out. This
|
||||
* is logically equivalent to an interrupted write to an ordinary file,
|
||||
* where some unknown portion of to-be-written data is persisted while
|
||||
* the remainder is not. Database integrity in such cases is maintained
|
||||
* (or not) by the same measures available for ordinary file access.
|
||||
*
|
||||
* State 2 is persistent under normal circumstances (when there is no
|
||||
* abnormal termination of a write operation such that data provided
|
||||
* to the underlying VFS write method has not yet reached storage.)
|
||||
*
|
||||
* In order to maintain the state invariant, the append mark is written
|
||||
* in advance of content writes where any part of such content would
|
||||
* overwrite an existing (or yet to be written) append mark.
|
||||
*/
|
||||
/* An open appendvfs file
|
||||
**
|
||||
** An instance of this structure describes the appended database file.
|
||||
** A separate sqlite3_file object is always appended. The appended
|
||||
** sqlite3_file object (which can be accessed using ORIGFILE()) describes
|
||||
** the entire file, including the prefix, the database, and the
|
||||
** append-mark.
|
||||
**
|
||||
** The structure of an AppendVFS database is like this:
|
||||
**
|
||||
** +-------------+---------+----------+-------------+
|
||||
** | prefix-file | padding | database | append-mark |
|
||||
** +-------------+---------+----------+-------------+
|
||||
** ^ ^
|
||||
** | |
|
||||
** iPgOne iMark
|
||||
**
|
||||
**
|
||||
** "prefix file" - file onto which the database has been appended.
|
||||
** "padding" - zero or more bytes inserted so that "database"
|
||||
** starts on an APND_ROUNDUP boundary
|
||||
** "database" - The SQLite database file
|
||||
** "append-mark" - The 25-byte "Start-Of-SQLite3-NNNNNNNN" that indicates
|
||||
** the offset from the start of prefix-file to the start
|
||||
** of "database".
|
||||
**
|
||||
** The size of the database is iMark - iPgOne.
|
||||
**
|
||||
** The NNNNNNNN in the "Start-Of-SQLite3-NNNNNNNN" suffix is the value
|
||||
** of iPgOne stored as a big-ending 64-bit integer.
|
||||
**
|
||||
** iMark will be the size of the underlying file minus 25 (APND_MARKSIZE).
|
||||
** Or, iMark is -1 to indicate that it has not yet been written.
|
||||
*/
|
||||
struct ApndFile {
|
||||
/* Access to IO methods of the underlying file */
|
||||
sqlite3_file base;
|
||||
/* File offset to beginning of appended content (unchanging) */
|
||||
sqlite3_int64 iPgOne;
|
||||
/* File offset of written append-mark, or -1 if unwritten */
|
||||
sqlite3_int64 iMark;
|
||||
/* Whenever file is open and .iMark >= 0, and file size changes are
|
||||
* not in progress, .iMark + sizeof(append mark) == base file size,
|
||||
* and append file size == .iMark - .iPgOne .
|
||||
*/
|
||||
sqlite3_file base; /* Subclass. MUST BE FIRST! */
|
||||
sqlite3_int64 iPgOne; /* Offset to the start of the database */
|
||||
sqlite3_int64 iMark; /* Offset of the append mark. -1 if unwritten */
|
||||
/* Always followed by another sqlite3_file that describes the whole file */
|
||||
};
|
||||
|
||||
/*
|
||||
@ -221,7 +225,6 @@ static const sqlite3_io_methods apnd_io_methods = {
|
||||
** Close an apnd-file.
|
||||
*/
|
||||
static int apndClose(sqlite3_file *pFile){
|
||||
assert((ApndFile*)pFile == ORIGFILE(pFile));
|
||||
pFile = ORIGFILE(pFile);
|
||||
return pFile->pMethods->xClose(pFile);
|
||||
}
|
||||
@ -255,9 +258,8 @@ static int apndWriteMark(
|
||||
int i = APND_MARK_FOS_SZ;
|
||||
int rc;
|
||||
assert(pFile == ORIGFILE(paf));
|
||||
/* assert(pFile == paf->base); */
|
||||
memcpy(a, APND_MARK_PREFIX, APND_MARK_PREFIX_SZ);
|
||||
while (--i >= 0) {
|
||||
while( --i >= 0 ){
|
||||
a[APND_MARK_PREFIX_SZ+i] = (unsigned char)(iPgOne & 0xff);
|
||||
iPgOne >>= 8;
|
||||
}
|
||||
@ -282,12 +284,10 @@ static int apndWrite(
|
||||
sqlite_int64 iWriteEnd = iOfst + iAmt;
|
||||
if( iWriteEnd>=APND_MAX_SIZE ) return SQLITE_FULL;
|
||||
pFile = ORIGFILE(pFile);
|
||||
/* assert(pFile == paf->base); */
|
||||
/* If append-mark is absent or will be overwritten, write it. */
|
||||
if( paf->iMark < 0 || paf->iPgOne + iWriteEnd > paf->iMark ){
|
||||
int rc = apndWriteMark(paf, pFile, iWriteEnd);
|
||||
if( SQLITE_OK!=rc )
|
||||
return rc;
|
||||
if( SQLITE_OK!=rc ) return rc;
|
||||
}
|
||||
return pFile->pMethods->xWrite(pFile, zBuf, iAmt, paf->iPgOne+iOfst);
|
||||
}
|
||||
@ -299,8 +299,7 @@ static int apndTruncate(sqlite3_file *pFile, sqlite_int64 size){
|
||||
ApndFile *paf = (ApndFile *)pFile;
|
||||
pFile = ORIGFILE(pFile);
|
||||
/* The append mark goes out first so truncate failure does not lose it. */
|
||||
if( SQLITE_OK!=apndWriteMark(paf, pFile, size) )
|
||||
return SQLITE_IOERR;
|
||||
if( SQLITE_OK!=apndWriteMark(paf, pFile, size) ) return SQLITE_IOERR;
|
||||
/* Truncate underlying file just past append mark */
|
||||
return pFile->pMethods->xTruncate(pFile, paf->iMark+APND_MARK_SIZE);
|
||||
}
|
||||
@ -416,8 +415,9 @@ static int apndFetch(
|
||||
void **pp
|
||||
){
|
||||
ApndFile *p = (ApndFile *)pFile;
|
||||
if( p->iMark < 0 || iOfst+iAmt > p->iMark)
|
||||
if( p->iMark < 0 || iOfst+iAmt > p->iMark ){
|
||||
return SQLITE_IOERR; /* Cannot read what is not yet there. */
|
||||
}
|
||||
pFile = ORIGFILE(pFile);
|
||||
return pFile->pMethods->xFetch(pFile, iOfst+p->iPgOne, iAmt, pp);
|
||||
}
|
||||
@ -468,14 +468,18 @@ static int apndIsAppendvfsDatabase(sqlite3_int64 sz, sqlite3_file *pFile){
|
||||
char zHdr[16];
|
||||
sqlite3_int64 iMark = apndReadMark(sz, pFile);
|
||||
if( iMark>=0 ){
|
||||
/* If file has right end-marker, the expected odd size, and the
|
||||
* SQLite DB type marker where the end-marker puts it, then it
|
||||
* is an appendvfs database (to be treated as such.)
|
||||
*/
|
||||
/* If file has the correct end-marker, the expected odd size, and the
|
||||
** SQLite DB type marker where the end-marker puts it, then it
|
||||
** is an appendvfs database.
|
||||
*/
|
||||
rc = pFile->pMethods->xRead(pFile, zHdr, sizeof(zHdr), iMark);
|
||||
if( SQLITE_OK==rc && memcmp(zHdr, apvfsSqliteHdr, sizeof(zHdr))==0
|
||||
&& (sz & 0x1ff)== APND_MARK_SIZE && sz>=512+APND_MARK_SIZE )
|
||||
if( SQLITE_OK==rc
|
||||
&& memcmp(zHdr, apvfsSqliteHdr, sizeof(zHdr))==0
|
||||
&& (sz & 0x1ff) == APND_MARK_SIZE
|
||||
&& sz>=512+APND_MARK_SIZE
|
||||
){
|
||||
return 1; /* It's an appendvfs database */
|
||||
}
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
@ -497,11 +501,6 @@ static int apndIsOrdinaryDatabaseFile(sqlite3_int64 sz, sqlite3_file *pFile){
|
||||
}
|
||||
}
|
||||
|
||||
/* Round-up used to get appendvfs portion to begin at a page boundary. */
|
||||
#define APND_ALIGN_MASK(nbits) ((1<<nbits)-1)
|
||||
#define APND_START_ROUNDUP(fsz, nbits) \
|
||||
( ((fsz)+APND_ALIGN_MASK(nbits)) & ~(sqlite3_int64)APND_ALIGN_MASK(nbits) )
|
||||
|
||||
/*
|
||||
** Open an apnd file handle.
|
||||
*/
|
||||
@ -519,49 +518,48 @@ static int apndOpen(
|
||||
sqlite3_int64 sz;
|
||||
if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){
|
||||
/* The appendvfs is not to be used for transient or temporary databases.
|
||||
* Just use the base VFS open to initialize the given file object and
|
||||
* open the underlying file. (Appendvfs is then unused for this file.)
|
||||
*/
|
||||
** Just use the base VFS open to initialize the given file object and
|
||||
** open the underlying file. (Appendvfs is then unused for this file.)
|
||||
*/
|
||||
return pBaseVfs->xOpen(pBaseVfs, zName, pFile, flags, pOutFlags);
|
||||
}
|
||||
memset(pApndFile, 0, sizeof(ApndFile));
|
||||
pFile->pMethods = &apnd_io_methods;
|
||||
/* Record that append mark has not been written until seen otherwise. */
|
||||
pApndFile->iMark = -1;
|
||||
pApndFile->iMark = -1; /* Append mark not yet written */
|
||||
|
||||
rc = pBaseVfs->xOpen(pBaseVfs, zName, pBaseFile, flags, pOutFlags);
|
||||
if( rc ) goto apnd_open_done;
|
||||
rc = pBaseFile->pMethods->xFileSize(pBaseFile, &sz);
|
||||
if( rc==SQLITE_OK ){
|
||||
rc = pBaseFile->pMethods->xFileSize(pBaseFile, &sz);
|
||||
}
|
||||
if( rc ){
|
||||
pBaseFile->pMethods->xClose(pBaseFile);
|
||||
goto apnd_open_done;
|
||||
pFile->pMethods = 0;
|
||||
return rc;
|
||||
}
|
||||
if( apndIsOrdinaryDatabaseFile(sz, pBaseFile) ){
|
||||
/* The file being opened appears to be just an ordinary DB. Copy
|
||||
* the base dispatch-table so this instance mimics the base VFS.
|
||||
*/
|
||||
** the base dispatch-table so this instance mimics the base VFS.
|
||||
*/
|
||||
memmove(pApndFile, pBaseFile, pBaseVfs->szOsFile);
|
||||
return SQLITE_OK;
|
||||
}
|
||||
pApndFile->iPgOne = apndReadMark(sz, pFile);
|
||||
if( pApndFile->iPgOne>=0 ){
|
||||
/* Append mark was found, infer its offset */
|
||||
pApndFile->iMark = sz - APND_MARK_SIZE;
|
||||
/* pApndFile->base = pBaseFile; */
|
||||
pApndFile->iMark = sz - APND_MARK_SIZE; /* Append mark found */
|
||||
return SQLITE_OK;
|
||||
}
|
||||
if( (flags & SQLITE_OPEN_CREATE)==0 ){
|
||||
pBaseFile->pMethods->xClose(pBaseFile);
|
||||
rc = SQLITE_CANTOPEN;
|
||||
pFile->pMethods = 0;
|
||||
}else{
|
||||
/* Round newly added appendvfs location to #define'd page boundary.
|
||||
** Note that nothing has yet been written to the underlying file.
|
||||
** The append mark will be written along with first content write.
|
||||
** Until then, paf->iMark value indicates it is not yet written.
|
||||
*/
|
||||
pApndFile->iPgOne = APND_START_ROUNDUP(sz);
|
||||
}
|
||||
/* Round newly added appendvfs location to #define'd page boundary.
|
||||
* Note that nothing has yet been written to the underlying file.
|
||||
* The append mark will be written along with first content write.
|
||||
* Until then, paf->iMark value indicates it is not yet written.
|
||||
*/
|
||||
pApndFile->iPgOne = APND_START_ROUNDUP(sz, APND_ROUNDUP_BITS);
|
||||
apnd_open_done:
|
||||
if( rc ) pFile->pMethods = 0;
|
||||
return rc;
|
||||
}
|
||||
|
||||
|
||||
14
manifest
14
manifest
@ -1,5 +1,5 @@
|
||||
C Fix\sassert\stypo.
|
||||
D 2021-03-16T07:06:29.878
|
||||
C Comment\sand\sstylistic\schanges\sto\sthe\sappendvfs.c\simplementation.
|
||||
D 2021-03-16T14:12:26.803
|
||||
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
|
||||
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
|
||||
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
|
||||
@ -286,7 +286,7 @@ F ext/lsm1/tool/mklsm1c.tcl f31561bbee5349f0a554d1ad7236ac1991fc09176626f529f607
|
||||
F ext/misc/README.md d6dd0fe1d8af77040216798a6a2b0c46c73054d2f0ea544fbbcdccf6f238c240
|
||||
F ext/misc/amatch.c e3ad5532799cee9a97647f483f67f43b38796b84b5a8c60594fe782a4338f358
|
||||
F ext/misc/anycollseq.c 5ffdfde9829eeac52219136ad6aa7cd9a4edb3b15f4f2532de52f4a22525eddb
|
||||
F ext/misc/appendvfs.c 1dad6e7dc162ad36367513c1f985a1b474c3f3517f53ba22a6a89ce980843098
|
||||
F ext/misc/appendvfs.c 390c411f14e66abb2f30b9023ebc57334288780c9388cdc6e0a25deb5d40e3b2
|
||||
F ext/misc/blobio.c a867c4c4617f6ec223a307ebfe0eabb45e0992f74dd47722b96f3e631c0edb2a
|
||||
F ext/misc/btreeinfo.c d28ce349b40054eaa9473e835837bad7a71deec33ba13e39f963d50933bfa0f9
|
||||
F ext/misc/carray.c b75a0f207391038bf1540d3372f482a95c3613511c7c474db51ede1196321c7c
|
||||
@ -1910,7 +1910,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
|
||||
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
|
||||
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
|
||||
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
|
||||
P eae8236f3b9bc326648d1c8fca61cb3c38f821d06fe915fd0978cffeb1f6152b
|
||||
R 32b396e0e85126b3386d72e2bc6e8e4c
|
||||
U larrybr
|
||||
Z f8d4366505c35a746a63af41266ec4f5
|
||||
P 3aedf818c1cfc88ee1103abd8b20e787f6be1bcc4c9350963f0cd52f5ac04154
|
||||
R d4d0d407c45719772ccdc3772a06a769
|
||||
U drh
|
||||
Z 2e9ac8f611b5ac99207230cf538d46c9
|
||||
|
||||
@ -1 +1 @@
|
||||
3aedf818c1cfc88ee1103abd8b20e787f6be1bcc4c9350963f0cd52f5ac04154
|
||||
25c3186aa143328157fb506a29802e87099cd14be4fa218230484a3212f20621
|
||||
Loading…
x
Reference in New Issue
Block a user