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sqlite/ext/misc/tmstmpvfs.c
drh 6444f694a6 Improved documentation (in the header comment) for tmstmpvfs.c. 
FossilOrigin-Name: 70b1da718c176b8eb154fe087af4352eb6f55c9c0d1f09fc625d073d9f8075f4
2026-01-12 14:45:55 +00:00

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/*
** 2026-01-05
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file implements a VFS shim that writes a timestamp and other tracing
** information into 16 byts of reserved space at the end of each page of the
** database file. The additional data is written as the page is added to
** the WAL file for databases in WAL mode, or as the database file itself
** is modified in rollback modes.
**
** The VFS also tries to generate log-files with names of the form:
**
** $(DATABASE)-tmstmp/$(TIME)-$(PID)-$(ID)
**
** Log files are only generated if directory $(DATABASE)-tmstmp exists.
** The name of each log file is the current ISO8601 time in milliseconds,
** the process ID, and a random 32-bit value (to disambiguate multiple
** connections from the same process) separated by dashes. The log file
** contains 16-bytes records for various events, such as opening or close
** of the database or WAL file, writes to the WAL file, checkpoints, and
** similar. The logfile is only generated if the connection attempts to
** modify the database. There is a separate log file for each open database
** connection.
**
** COMPILING
**
** To build this extension as a separately loaded shared library or
** DLL, use compiler command-lines similar to the following:
**
** (linux) gcc -fPIC -shared tmstmpvfs.c -o tmstmpvfs.so
** (mac) clang -fPIC -dynamiclib tmstmpvfs.c -o tmstmpvfs.dylib
** (windows) cl tmstmpvfs.c -link -dll -out:tmstmpvfs.dll
**
** You may want to add additional compiler options, of course,
** according to the needs of your project.
**
** Another option is to statically link both SQLite and this extension
** into your application. If both this file and "sqlite3.c" are statically
** linked, and if "sqlite3.c" is compiled with -DSQLITE_EXTRA_INIT=
** SQLite amalgamation "sqlite3.c" file with the option like:
**
** -DSQLITE_EXTRA_INIT=sqlite3_register_tmstmpvfs
**
** Then SQLite will use the tmstmp VFS by default throughout your
** application.
**
** LOADING
**
** To load this extension as a shared library, you first have to
** bring up a dummy SQLite database connection to use as the argument
** to the sqlite3_load_extension() API call. Then you invoke the
** sqlite3_load_extension() API and shutdown the dummy database
** connection. All subsequent database connections that are opened
** will include this extension. For example:
**
** sqlite3 *db;
** sqlite3_open(":memory:", &db);
** sqlite3_load_extension(db, "./tmstmpvfs");
** sqlite3_close(db);
**
** Tmstmpvfs is a VFS Shim. When loaded, "tmstmpvfs" becomes the new
** default VFS and it uses the prior default VFS as the next VFS
** down in the stack. This is normally what you want. However, in
** complex situations where multiple VFS shims are being loaded,
** it might be important to ensure that tmstmpvfs is loaded in the
** correct order so that it sequences itself into the default VFS
** Shim stack in the right order.
**
** When running the CLI, you can load this extension at invocation by
** adding a command-line option like this: "--vfs ./tmstmpvfs.so".
** The --vfs option usually specifies the symbolic name of a built-in VFS.
** But if the argument to --vfs is not a built-in VFS but is instead the
** name of a file, the CLI tries to load that file as an extension. Note
** that the full name of the extension file must be provided, including
** the ".so" or ".dylib" or ".dll" suffix.
**
** An application can see if the tmstmpvfs is being used by examining
** the results from SQLITE_FCNTL_VFSNAME (or the .vfsname command in
** the CLI). If the answer include "tmstmp", then this VFS is being
** used.
**
** USING
**
** Open database connections using the sqlite3_open() or
** sqlite3_open_v2() interfaces, as normal. Ordinary database files
** (without a timestamp) will operate normally.
**
** Timestamping only works on databases that have a reserve-bytes
** value of exactly 16. The default value for reserve-bytes is 0.
** Hence, newly created database files will omit the timestamp by
** default. To create a database that includes a timestamp, change
** the reserve-bytes value to 16 by running:
**
** int n = 16;
** sqlite3_file_control(db, 0, SQLITE_FCNTL_RESERVE_BYTES, &n);
**
** If you do this immediately after creating a new database file,
** before anything else has been written into the file, then that
** might be all that you need to do. Otherwise, the API call
** above should be followed by:
**
** sqlite3_exec(db, "VACUUM", 0, 0, 0);
**
** It never hurts to run the VACUUM, even if you don't need it.
**
** From the CLI, use the ".filectrl reserve_bytes 16" command,
** followed by "VACUUM;".
**
** SQLite allows the number of reserve-bytes to be increased, but
** not decreased. If you want to restore the reserve-bytes to 0
** (to disable tmstmpvfs), the easiest approach is to use VACUUM INTO
** with a URI filename as the argument and include "reserve=0" query
** parameter on the URI. Example:
**
** VACUUM INTO 'file:notimestamps.db?reserve=0';
**
** Then switch over to using the new database file. The reserve=0 query
** parameter only works on SQLite 3.52.0 and later.
**
** IMPLEMENTATION NOTES
**
** The timestamp information is stored in the last 16 bytes of each page.
** This module only operates if the "bytes of reserved space on each page"
** value at offset 20 the SQLite database header is exactly 16. If
** the reserved-space value is not 16, no timestamp information is added
** to database pages. Some, but not all, logfile entries will be made
** still, but the size of the logs will be greatly reduced.
**
** The timestamp layout is as follows:
**
** bytes 0,1 Zero. Reserved for future expansion
** bytes 2-7 Milliseconds since the Unix Epoch
** bytes 8-11 WAL frame number
** bytes 12 0: WAL write 1: WAL txn 2: rollback write
** bytes 13-15 Lower 24 bits of Salt-1
**
** For transactions that occur in rollback mode, only the timestamp
** in bytes 2-7 and byte 12 are non-zero. Byte 12 is set to 2 for
** rollback writes.
**
** LOGGING
**
** An open database connection that attempts to write to the database
** will create a log file if a directory name $(DATABASE)-tmstmp exists.
** The name of the log file is:
**
** $(TIME)-$(PID)-$(RANDOM)
**
** Where TIME is an ISO 8601 date in milliseconds with no punctuation,
** PID is the process ID, and RANDOM is a 32-bit random number expressed
** as hexadecimal.
**
** The log consists of 16-byte records. Each record consists of five
** unsigned integers:
**
** 1 1 6 4 4 <--- bytes
** op a1 ts a2 a3
**
** The meanings of the a1-a3 values depend on op. ts is the timestamp
** in milliseconds since the unix epoch (1970-01-01 00:00:00).
** Opcodes are defined by the ELOG_* #defines below.
**
** ELOG_OPEN_DB "Open a connection to the database file"
** op = 0x01
** a2 = process-ID
**
** ELOG_OPEN_WAL "Open a connection to the -wal file"
** op = 0x02
** a2 = process-ID
**
** ELOG_WAL_PAGE "New page added to the WAL file"
** op = 0x03
** a1 = 1 if last page of a txn. 0 otherwise.
** a2 = page number in the DB file
** a3 = frame number in the WAL file
**
** ELOG_DB_PAGE "Database page updated using rollback mode"
** op = 0x04
** a2 = page number in the DB file
**
** ELOG_CKPT_START "Start of a checkpoint operation"
** op = 0x05
**
** ELOG_CKPT_PAGE "Page xfer from WAL to database"
** op = 0x06
** a2 = database page number
**
** ELOG_CKPT_END "Start of a checkpoint operation"
** op = 0x07
**
** ELOG_WAL_RESET "WAL file header overwritten"
** op = 0x08
** a3 = Salt1 value
**
** ELOG_CLOSE_WAL "Close the WAL file connection"
** op = 0x0e
**
** ELOG_CLOSE_DB "Close the DB connection"
** op = 0x0f
*/
#if defined(SQLITE_AMALGAMATION) && !defined(SQLITE_TMSTMPVFS_STATIC)
# define SQLITE_TMSTMPVFS_STATIC
#endif
#ifdef SQLITE_TMSTMPVFS_STATIC
# include "sqlite3.h"
#else
# include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#endif
#include <string.h>
#include <assert.h>
#include <stdio.h>
/*
** Forward declaration of objects used by this utility
*/
typedef struct sqlite3_vfs TmstmpVfs;
typedef struct TmstmpFile TmstmpFile;
typedef struct TmstmpLog TmstmpLog;
/*
** Bytes of reserved space used by this extension
*/
#define TMSTMP_RESERVE 16
/*
** The magic number used to identify TmstmpFile objects
*/
#define TMSTMP_MAGIC 0x2a87b72d
/*
** Useful datatype abbreviations
*/
#if !defined(SQLITE_AMALGAMATION)
typedef unsigned char u8;
typedef unsigned int u32;
#endif
/*
** Current process id
*/
#if defined(_WIN32)
# include <windows.h>
# define GETPID (u32)GetCurrentProcessId()
#else
# include <unistd.h>
# define GETPID (u32)getpid()
#endif
/* Access to a lower-level VFS that (might) implement dynamic loading,
** access to randomness, etc.
*/
#define ORIGVFS(p) ((sqlite3_vfs*)((p)->pAppData))
#define ORIGFILE(p) ((sqlite3_file*)(((TmstmpFile*)(p))+1))
/* Information for the tmstmp log file. */
struct TmstmpLog {
char *zLogname; /* Log filename */
FILE *log; /* Open log file */
int n; /* Bytes of a[] used */
unsigned char a[16*6]; /* Buffered header for the log */
};
/* An open WAL file */
struct TmstmpFile {
sqlite3_file base; /* IO methods */
u32 uMagic; /* Magic number for sanity checking */
u32 salt1; /* Last WAL salt-1 value */
u32 iFrame; /* Last WAL frame number */
u32 pgno; /* Current page number */
u32 pgsz; /* Size of each page, in bytes */
u8 isWal; /* True if this is a WAL file */
u8 isDb; /* True if this is a DB file */
u8 isCommit; /* Last WAL frame header was a transaction commit */
u8 hasCorrectReserve; /* File has the correct reserve size */
u8 inCkpt; /* True if in a checkpoint */
TmstmpLog *pLog; /* Log file */
TmstmpFile *pPartner; /* DB->WAL or WAL->DB mapping */
sqlite3_int64 iOfst; /* Offset of last WAL frame header */
sqlite3_vfs *pSubVfs; /* Underlying VFS */
};
/*
** Event log opcodes
*/
#define ELOG_OPEN_DB 0x01
#define ELOG_OPEN_WAL 0x02
#define ELOG_WAL_PAGE 0x03
#define ELOG_DB_PAGE 0x04
#define ELOG_CKPT_START 0x05
#define ELOG_CKPT_PAGE 0x06
#define ELOG_CKPT_DONE 0x07
#define ELOG_WAL_RESET 0x08
#define ELOG_CLOSE_WAL 0x0e
#define ELOG_CLOSE_DB 0x0f
/*
** Methods for TmstmpFile
*/
static int tmstmpClose(sqlite3_file*);
static int tmstmpRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int tmstmpWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst);
static int tmstmpTruncate(sqlite3_file*, sqlite3_int64 size);
static int tmstmpSync(sqlite3_file*, int flags);
static int tmstmpFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int tmstmpLock(sqlite3_file*, int);
static int tmstmpUnlock(sqlite3_file*, int);
static int tmstmpCheckReservedLock(sqlite3_file*, int *pResOut);
static int tmstmpFileControl(sqlite3_file*, int op, void *pArg);
static int tmstmpSectorSize(sqlite3_file*);
static int tmstmpDeviceCharacteristics(sqlite3_file*);
static int tmstmpShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
static int tmstmpShmLock(sqlite3_file*, int offset, int n, int flags);
static void tmstmpShmBarrier(sqlite3_file*);
static int tmstmpShmUnmap(sqlite3_file*, int deleteFlag);
static int tmstmpFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
static int tmstmpUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
/*
** Methods for TmstmpVfs
*/
static int tmstmpOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *);
static int tmstmpDelete(sqlite3_vfs*, const char *zName, int syncDir);
static int tmstmpAccess(sqlite3_vfs*, const char *zName, int flags, int *);
static int tmstmpFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
static void *tmstmpDlOpen(sqlite3_vfs*, const char *zFilename);
static void tmstmpDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
static void (*tmstmpDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void);
static void tmstmpDlClose(sqlite3_vfs*, void*);
static int tmstmpRandomness(sqlite3_vfs*, int nByte, char *zOut);
static int tmstmpSleep(sqlite3_vfs*, int microseconds);
static int tmstmpCurrentTime(sqlite3_vfs*, double*);
static int tmstmpGetLastError(sqlite3_vfs*, int, char *);
static int tmstmpCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*);
static int tmstmpSetSystemCall(sqlite3_vfs*, const char*,sqlite3_syscall_ptr);
static sqlite3_syscall_ptr tmstmpGetSystemCall(sqlite3_vfs*, const char *z);
static const char *tmstmpNextSystemCall(sqlite3_vfs*, const char *zName);
static sqlite3_vfs tmstmp_vfs = {
3, /* iVersion (set when registered) */
0, /* szOsFile (set when registered) */
1024, /* mxPathname */
0, /* pNext */
"tmstmpvfs", /* zName */
0, /* pAppData (set when registered) */
tmstmpOpen, /* xOpen */
tmstmpDelete, /* xDelete */
tmstmpAccess, /* xAccess */
tmstmpFullPathname, /* xFullPathname */
tmstmpDlOpen, /* xDlOpen */
tmstmpDlError, /* xDlError */
tmstmpDlSym, /* xDlSym */
tmstmpDlClose, /* xDlClose */
tmstmpRandomness, /* xRandomness */
tmstmpSleep, /* xSleep */
tmstmpCurrentTime, /* xCurrentTime */
tmstmpGetLastError, /* xGetLastError */
tmstmpCurrentTimeInt64, /* xCurrentTimeInt64 */
tmstmpSetSystemCall, /* xSetSystemCall */
tmstmpGetSystemCall, /* xGetSystemCall */
tmstmpNextSystemCall /* xNextSystemCall */
};
static const sqlite3_io_methods tmstmp_io_methods = {
3, /* iVersion */
tmstmpClose, /* xClose */
tmstmpRead, /* xRead */
tmstmpWrite, /* xWrite */
tmstmpTruncate, /* xTruncate */
tmstmpSync, /* xSync */
tmstmpFileSize, /* xFileSize */
tmstmpLock, /* xLock */
tmstmpUnlock, /* xUnlock */
tmstmpCheckReservedLock, /* xCheckReservedLock */
tmstmpFileControl, /* xFileControl */
tmstmpSectorSize, /* xSectorSize */
tmstmpDeviceCharacteristics, /* xDeviceCharacteristics */
tmstmpShmMap, /* xShmMap */
tmstmpShmLock, /* xShmLock */
tmstmpShmBarrier, /* xShmBarrier */
tmstmpShmUnmap, /* xShmUnmap */
tmstmpFetch, /* xFetch */
tmstmpUnfetch /* xUnfetch */
};
/*
** Write a 6-byte millisecond timestamp into aOut[]
*/
static void tmstmpPutTS(TmstmpFile *p, unsigned char *aOut){
sqlite3_uint64 tm = 0;
p->pSubVfs->xCurrentTimeInt64(p->pSubVfs, (sqlite3_int64*)&tm);
tm -= 210866760000000LL;
aOut[0] = (tm>>40)&0xff;
aOut[1] = (tm>>32)&0xff;
aOut[2] = (tm>>24)&0xff;
aOut[3] = (tm>>16)&0xff;
aOut[4] = (tm>>8)&0xff;
aOut[5] = tm&0xff;
}
/*
** Read a 32-bit big-endian unsigned integer and return it.
*/
static u32 tmstmpGetU32(const unsigned char *a){
return (a[0]<<24) + (a[1]<<16) + (a[2]<<8) + a[3];
}
/* Write a 32-bit integer as big-ending into a[]
*/
static void tmstmpPutU32(u32 v, unsigned char *a){
a[0] = (v>>24) & 0xff;
a[1] = (v>>16) & 0xff;
a[2] = (v>>8) & 0xff;
a[3] = v & 0xff;
}
/* Free a TmstmpLog object */
static void tmstmpLogFree(TmstmpLog *pLog){
if( pLog==0 ) return;
sqlite3_free(pLog->zLogname);
sqlite3_free(pLog);
}
/* Flush log content. Open the file if necessary. Return the
** number of errors. */
static int tmstmpLogFlush(TmstmpFile *p){
TmstmpLog *pLog = p->pLog;
assert( pLog!=0 );
if( pLog->log==0 ){
pLog->log = fopen(pLog->zLogname, "wb");
if( pLog->log==0 ){
tmstmpLogFree(pLog);
p->pLog = 0;
return 1;
}
}
(void)fwrite(pLog->a, pLog->n, 1, pLog->log);
pLog->n = 0;
return 0;
}
/*
** Write a record onto the event log
*/
static void tmstmpEvent(
TmstmpFile *p,
u8 op,
u8 a1,
u32 a2,
u32 a3
){
unsigned char *a;
TmstmpLog *pLog;
if( p->isWal ){
p = p->pPartner;
assert( p!=0 );
assert( p->isDb );
}
pLog = p->pLog;
if( pLog==0 ) return;
if( pLog->n >= (int)sizeof(pLog->a) ){
if( tmstmpLogFlush(p) ) return;
}
a = pLog->a + pLog->n;
a[0] = op;
a[1] = a1;
tmstmpPutTS(p, a+2);
tmstmpPutU32(a2, a+8);
tmstmpPutU32(a3, a+12);
pLog->n += 16;
if( pLog->log || (op>=ELOG_WAL_PAGE && op<=ELOG_WAL_RESET) ){
(void)tmstmpLogFlush(p);
}
}
/*
** Close a connection
*/
static int tmstmpClose(sqlite3_file *pFile){
TmstmpFile *p = (TmstmpFile *)pFile;
if( p->hasCorrectReserve ){
tmstmpEvent(p, p->isDb ? ELOG_CLOSE_DB : ELOG_CLOSE_WAL, 0, 0, 0);
}
tmstmpLogFree(p->pLog);
if( p->pPartner ){
assert( p->pPartner->pPartner==p );
p->pPartner->pPartner = 0;
p->pPartner = 0;
}
pFile = ORIGFILE(pFile);
return pFile->pMethods->xClose(pFile);
}
/*
** Read bytes from a file
*/
static int tmstmpRead(
sqlite3_file *pFile,
void *zBuf,
int iAmt,
sqlite_int64 iOfst
){
int rc;
TmstmpFile *p = (TmstmpFile*)pFile;
pFile = ORIGFILE(pFile);
rc = pFile->pMethods->xRead(pFile, zBuf, iAmt, iOfst);
if( rc!=SQLITE_OK ) return rc;
if( p->isDb
&& iOfst==0
&& iAmt>=100
){
const unsigned char *a = (unsigned char*)zBuf;
p->hasCorrectReserve = (a[20]==TMSTMP_RESERVE);
p->pgsz = (a[16]<<8) + a[17];
if( p->pgsz==1 ) p->pgsz = 65536;
if( p->pPartner ){
p->pPartner->hasCorrectReserve = p->hasCorrectReserve;
p->pPartner->pgsz = p->pgsz;
}
}
return rc;
}
/*
** Write data to a tmstmp-file.
*/
static int tmstmpWrite(
sqlite3_file *pFile,
const void *zBuf,
int iAmt,
sqlite_int64 iOfst
){
TmstmpFile *p = (TmstmpFile*)pFile;
sqlite3_file *pSub = ORIGFILE(pFile);
if( !p->hasCorrectReserve ){
/* The database does not have the correct reserve size. No-op */
}else if( p->isWal ){
/* Writing into a WAL file */
if( iAmt==24 ){
/* A frame header */
u32 x = 0;
p->iFrame = (iOfst - 32)/(p->pgsz+24);
p->pgno = tmstmpGetU32((const u8*)zBuf);
p->salt1 = tmstmpGetU32(((const u8*)zBuf)+8);
memcpy(&x, ((const u8*)zBuf)+4, 4);
p->isCommit = (x!=0);
p->iOfst = iOfst;
}else if( iAmt>=512 && iOfst==p->iOfst+24 ){
unsigned char *s = (unsigned char*)zBuf+iAmt-TMSTMP_RESERVE;
memset(s, 0, TMSTMP_RESERVE);
tmstmpPutTS(p, s+2);
tmstmpPutU32(p->iFrame, s+8);
tmstmpPutU32(p->salt1, s+12);
s[12] = p->isCommit ? 1 : 0;
tmstmpEvent(p, ELOG_WAL_PAGE, s[12], p->pgno, p->iFrame);
}else if( iAmt==32 && iOfst==0 ){
u32 salt1 = tmstmpGetU32(((const u8*)zBuf)+16);
tmstmpEvent(p, ELOG_WAL_RESET, 0, 0, salt1);
}
}else if( p->inCkpt ){
assert( p->pgsz>0 );
tmstmpEvent(p, ELOG_CKPT_PAGE, 0, (iOfst/p->pgsz)+1, 0);
}else if( p->pPartner==0 ){
/* Writing into a database in rollback mode */
unsigned char *s = (unsigned char*)zBuf+iAmt-TMSTMP_RESERVE;
memset(s, 0, TMSTMP_RESERVE);
tmstmpPutTS(p, s+2);
s[12] = 2;
assert( p->pgsz>0 );
tmstmpEvent(p, ELOG_DB_PAGE, 0, (u32)(iOfst/p->pgsz), 0);
}
return pSub->pMethods->xWrite(pSub,zBuf,iAmt,iOfst);
}
/*
** Truncate a tmstmp-file.
*/
static int tmstmpTruncate(sqlite3_file *pFile, sqlite_int64 size){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xTruncate(pFile, size);
}
/*
** Sync a tmstmp-file.
*/
static int tmstmpSync(sqlite3_file *pFile, int flags){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xSync(pFile, flags);
}
/*
** Return the current file-size of a tmstmp-file.
*/
static int tmstmpFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
TmstmpFile *p = (TmstmpFile *)pFile;
pFile = ORIGFILE(p);
return pFile->pMethods->xFileSize(pFile, pSize);
}
/*
** Lock a tmstmp-file.
*/
static int tmstmpLock(sqlite3_file *pFile, int eLock){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xLock(pFile, eLock);
}
/*
** Unlock a tmstmp-file.
*/
static int tmstmpUnlock(sqlite3_file *pFile, int eLock){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xUnlock(pFile, eLock);
}
/*
** Check if another file-handle holds a RESERVED lock on a tmstmp-file.
*/
static int tmstmpCheckReservedLock(sqlite3_file *pFile, int *pResOut){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xCheckReservedLock(pFile, pResOut);
}
/*
** File control method. For custom operations on a tmstmp-file.
*/
static int tmstmpFileControl(sqlite3_file *pFile, int op, void *pArg){
int rc;
TmstmpFile *p = (TmstmpFile*)pFile;
pFile = ORIGFILE(pFile);
rc = pFile->pMethods->xFileControl(pFile, op, pArg);
switch( op ){
case SQLITE_FCNTL_VFSNAME: {
if( p->hasCorrectReserve && rc==SQLITE_OK ){
*(char**)pArg = sqlite3_mprintf("tmstmp/%z", *(char**)pArg);
}
break;
}
case SQLITE_FCNTL_CKPT_START: {
p->inCkpt = 1;
assert( p->isDb );
assert( p->pPartner!=0 );
p->pPartner->inCkpt = 1;
if( p->hasCorrectReserve ){
tmstmpEvent(p, ELOG_CKPT_START, 0, 0, 0);
}
rc = SQLITE_OK;
break;
}
case SQLITE_FCNTL_CKPT_DONE: {
p->inCkpt = 0;
assert( p->isDb );
assert( p->pPartner!=0 );
p->pPartner->inCkpt = 0;
if( p->hasCorrectReserve ){
tmstmpEvent(p, ELOG_CKPT_DONE, 0, 0, 0);
}
rc = SQLITE_OK;
break;
}
}
return rc;
}
/*
** Return the sector-size in bytes for a tmstmp-file.
*/
static int tmstmpSectorSize(sqlite3_file *pFile){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xSectorSize(pFile);
}
/*
** Return the device characteristic flags supported by a tmstmp-file.
*/
static int tmstmpDeviceCharacteristics(sqlite3_file *pFile){
int devchar = 0;
pFile = ORIGFILE(pFile);
devchar = pFile->pMethods->xDeviceCharacteristics(pFile);
return (devchar & ~SQLITE_IOCAP_SUBPAGE_READ);
}
/* Create a shared memory file mapping */
static int tmstmpShmMap(
sqlite3_file *pFile,
int iPg,
int pgsz,
int bExtend,
void volatile **pp
){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xShmMap(pFile,iPg,pgsz,bExtend,pp);
}
/* Perform locking on a shared-memory segment */
static int tmstmpShmLock(sqlite3_file *pFile, int offset, int n, int flags){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xShmLock(pFile,offset,n,flags);
}
/* Memory barrier operation on shared memory */
static void tmstmpShmBarrier(sqlite3_file *pFile){
pFile = ORIGFILE(pFile);
pFile->pMethods->xShmBarrier(pFile);
}
/* Unmap a shared memory segment */
static int tmstmpShmUnmap(sqlite3_file *pFile, int deleteFlag){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xShmUnmap(pFile,deleteFlag);
}
/* Fetch a page of a memory-mapped file */
static int tmstmpFetch(
sqlite3_file *pFile,
sqlite3_int64 iOfst,
int iAmt,
void **pp
){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xFetch(pFile, iOfst, iAmt, pp);
}
/* Release a memory-mapped page */
static int tmstmpUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){
pFile = ORIGFILE(pFile);
return pFile->pMethods->xUnfetch(pFile, iOfst, pPage);
}
/*
** Open a tmstmp file handle.
*/
static int tmstmpOpen(
sqlite3_vfs *pVfs,
const char *zName,
sqlite3_file *pFile,
int flags,
int *pOutFlags
){
TmstmpFile *p, *pDb;
sqlite3_file *pSubFile;
sqlite3_vfs *pSubVfs;
int rc;
pSubVfs = ORIGVFS(pVfs);
if( (flags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_WAL))==0 ){
/* If the file is not a persistent database or a WAL file, then
** bypass the timestamp logic all together */
return pSubVfs->xOpen(pSubVfs, zName, pFile, flags, pOutFlags);
}
if( (flags & SQLITE_OPEN_WAL)!=0 ){
pDb = (TmstmpFile*)sqlite3_database_file_object(zName);
if( pDb==0
|| pDb->uMagic!=TMSTMP_MAGIC
|| !pDb->isDb
|| pDb->pPartner!=0
){
return pSubVfs->xOpen(pSubVfs, zName, pFile, flags, pOutFlags);
}
}else{
pDb = 0;
}
p = (TmstmpFile*)pFile;
memset(p, 0, sizeof(*p));
pSubFile = ORIGFILE(pFile);
pFile->pMethods = &tmstmp_io_methods;
p->pSubVfs = pSubVfs;
p->uMagic = TMSTMP_MAGIC;
rc = pSubVfs->xOpen(pSubVfs, zName, pSubFile, flags, pOutFlags);
if( rc ) goto tmstmp_open_done;
if( pDb!=0 ){
p->isWal = 1;
p->pPartner = pDb;
pDb->pPartner = p;
}else{
u32 r2;
u32 pid;
TmstmpLog *pLog;
sqlite3_uint64 r1; /* Milliseconds since 1970-01-01 */
sqlite3_uint64 days; /* Days since 1970-01-01 */
sqlite3_uint64 sod; /* Start of date specified by ms */
sqlite3_uint64 z; /* Days since 0000-03-01 */
sqlite3_uint64 era; /* 400-year era */
int h; /* hour */
int m; /* minute */
int s; /* second */
int f; /* millisecond */
int Y; /* year */
int M; /* month */
int D; /* day */
int y; /* year assuming March is first month */
unsigned int doe; /* day of 400-year era */
unsigned int yoe; /* year of 400-year era */
unsigned int doy; /* day of year */
unsigned int mp; /* month with March==0 */
p->isDb = 1;
r1 = 0;
pLog = sqlite3_malloc64( sizeof(TmstmpLog) );
if( pLog==0 ){
return SQLITE_NOMEM;
}
memset(pLog, 0, sizeof(pLog[0]));
p->pLog = pLog;
p->pSubVfs->xCurrentTimeInt64(p->pSubVfs, (sqlite3_int64*)&r1);
r1 -= 210866760000000LL;
days = r1/86400000;
sod = (r1%86400000)/1000;
f = (int)(r1%1000);
h = sod/3600;
m = (sod%3600)/60;
s = sod%60;
z = days + 719468;
era = z/147097;
doe = (unsigned)(z - era*146097);
yoe = (doe - doe/1460 + doe/36524 - doe/146096)/365;
y = (int)yoe + era*400;
doy = doe - (365*yoe + yoe/4 - yoe/100);
mp = (5*doy + 2)/153;
D = doy - (153*mp + 2)/5 + 1;
M = mp + (mp<10 ? 3 : -9);
Y = y + (M <=2);
sqlite3_randomness(sizeof(r2), &r2);
pid = GETPID;
pLog->zLogname = sqlite3_mprintf(
"%s-tmstmp/%04d%02d%02dT%02d%02d%02d%03d-%08d-%08x",
zName, Y, M, D, h, m, s, f, pid, r2);
}
tmstmpEvent(p, p->isWal ? ELOG_OPEN_WAL : ELOG_OPEN_DB, 0, GETPID, 0);
tmstmp_open_done:
if( rc ) pFile->pMethods = 0;
return rc;
}
/*
** All VFS interfaces other than xOpen are passed down into the Sub-VFS.
*/
static int tmstmpDelete(sqlite3_vfs *p, const char *zName, int syncDir){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xDelete(pSub,zName,syncDir);
}
static int tmstmpAccess(sqlite3_vfs *p, const char *zName, int flags, int *pR){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xAccess(pSub,zName,flags,pR);
}
static int tmstmpFullPathname(sqlite3_vfs*p,const char *zName,int n,char *zOut){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xFullPathname(pSub,zName,n,zOut);
}
static void *tmstmpDlOpen(sqlite3_vfs *p, const char *zFilename){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xDlOpen(pSub,zFilename);
}
static void tmstmpDlError(sqlite3_vfs *p, int nByte, char *zErrMsg){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xDlError(pSub,nByte,zErrMsg);
}
static void(*tmstmpDlSym(sqlite3_vfs *p, void *pDl, const char *zSym))(void){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xDlSym(pSub,pDl,zSym);
}
static void tmstmpDlClose(sqlite3_vfs *p, void *pDl){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xDlClose(pSub,pDl);
}
static int tmstmpRandomness(sqlite3_vfs *p, int nByte, char *zOut){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xRandomness(pSub,nByte,zOut);
}
static int tmstmpSleep(sqlite3_vfs *p, int microseconds){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xSleep(pSub,microseconds);
}
static int tmstmpCurrentTime(sqlite3_vfs *p, double *prNow){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xCurrentTime(pSub,prNow);
}
static int tmstmpGetLastError(sqlite3_vfs *p, int a, char *b){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xGetLastError(pSub,a,b);
}
static int tmstmpCurrentTimeInt64(sqlite3_vfs *p, sqlite3_int64 *piNow){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xCurrentTimeInt64(pSub,piNow);
}
static int tmstmpSetSystemCall(sqlite3_vfs *p, const char *zName,
sqlite3_syscall_ptr x){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xSetSystemCall(pSub,zName,x);
}
static sqlite3_syscall_ptr tmstmpGetSystemCall(sqlite3_vfs *p, const char *z){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xGetSystemCall(pSub,z);
}
static const char *tmstmpNextSystemCall(sqlite3_vfs *p, const char *zName){
sqlite3_vfs *pSub = ORIGVFS(p);
return pSub->xNextSystemCall(pSub,zName);
}
/*
** Register the tmstmp VFS as the default VFS for the system.
*/
static int tmstmpRegisterVfs(void){
int rc = SQLITE_OK;
sqlite3_vfs *pOrig = sqlite3_vfs_find(0);
if( pOrig==0 ) return SQLITE_ERROR;
if( pOrig==&tmstmp_vfs ) return SQLITE_OK;
tmstmp_vfs.iVersion = pOrig->iVersion;
tmstmp_vfs.pAppData = pOrig;
tmstmp_vfs.szOsFile = pOrig->szOsFile + sizeof(TmstmpFile);
rc = sqlite3_vfs_register(&tmstmp_vfs, 1);
return rc;
}
#if defined(SQLITE_TMSTMPVFS_STATIC)
/* This variant of the initializer runs when the extension is
** statically linked.
*/
int sqlite3_register_tmstmpvfs(const char *NotUsed){
(void)NotUsed;
return tmstmpRegisterVfs();
}
int sqlite3_unregister_tmstmpvfs(void){
if( sqlite3_vfs_find("tmstmpvfs") ){
sqlite3_vfs_unregister(&tmstmp_vfs);
}
return SQLITE_OK;
}
#endif /* defined(SQLITE_TMSTMPVFS_STATIC */
#if !defined(SQLITE_TMSTMPVFS_STATIC)
/* This variant of the initializer function is used when the
** extension is shared library to be loaded at run-time.
*/
#ifdef _WIN32
__declspec(dllexport)
#endif
/*
** This routine is called by sqlite3_load_extension() when the
** extension is first loaded.
***/
int sqlite3_tmstmpvfs_init(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pApi
){
int rc;
SQLITE_EXTENSION_INIT2(pApi);
(void)pzErrMsg; /* not used */
(void)db; /* not used */
rc = tmstmpRegisterVfs();
if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY;
return rc;
}
#endif /* !defined(SQLITE_TMSTMPVFS_STATIC) */
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