Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
Comment: | Snapshot documentation updates. Comment changes only - no changes to code. |
---|---|
Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | snapshot-get |
Files: | files | file ages | folders |
SHA1: |
ef51a398a04963508389ffe2f9d8359c |
User & Date: | drh 2015-12-10 22:48:22.684 |
Context
2015-12-11
| ||
01:22 | Fix a bad assert related to snapshots. (check-in: 767ee30efa user: drh tags: snapshot-get) | |
2015-12-10
| ||
22:48 | Snapshot documentation updates. Comment changes only - no changes to code. (check-in: ef51a398a0 user: drh tags: snapshot-get) | |
20:03 | Update the sqlite3_snapshot_get() API so that if the caller does not have an open read transaction on the named database, one is automatically opened. (check-in: b9c90f1029 user: dan tags: snapshot-get) | |
Changes
Changes to src/sqlite.h.in.
︙ | ︙ | |||
4401 4402 4403 4404 4405 4406 4407 | ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a ** memory allocation fails. ** ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object ** previously obtained from [sqlite3_value_dup()]. ^If V is a NULL pointer ** then sqlite3_value_free(V) is a harmless no-op. */ | | | | 4401 4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 | ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a ** memory allocation fails. ** ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object ** previously obtained from [sqlite3_value_dup()]. ^If V is a NULL pointer ** then sqlite3_value_free(V) is a harmless no-op. */ sqlite3_value *sqlite3_value_dup(const sqlite3_value*); void sqlite3_value_free(sqlite3_value*); /* ** CAPI3REF: Obtain Aggregate Function Context ** METHOD: sqlite3_context ** ** Implementations of aggregate SQL functions use this ** routine to allocate memory for storing their state. |
︙ | ︙ | |||
7847 7848 7849 7850 7851 7852 7853 | ** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined. */ void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*); /* ** CAPI3REF: Flush caches to disk mid-transaction ** | | > | | > | | | | | | | | | | < | < < < < | < < > | > | | < | < > > > | > > | < < < < | | < < > | < < < < < < < < < < < < < < < > > > > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > > > > > > > > > > > > | < | 7847 7848 7849 7850 7851 7852 7853 7854 7855 7856 7857 7858 7859 7860 7861 7862 7863 7864 7865 7866 7867 7868 7869 7870 7871 7872 7873 7874 7875 7876 7877 7878 7879 7880 7881 7882 7883 7884 7885 7886 7887 7888 7889 7890 7891 7892 7893 7894 7895 7896 7897 7898 7899 7900 7901 7902 7903 7904 7905 7906 7907 7908 7909 7910 7911 7912 7913 7914 7915 7916 7917 7918 7919 7920 7921 7922 7923 7924 7925 7926 7927 7928 7929 7930 7931 7932 7933 7934 7935 7936 7937 7938 7939 7940 7941 7942 7943 7944 7945 7946 7947 7948 7949 7950 7951 7952 7953 7954 7955 7956 7957 7958 7959 7960 7961 7962 7963 7964 7965 7966 7967 7968 7969 | ** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined. */ void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*); /* ** CAPI3REF: Flush caches to disk mid-transaction ** ** ^If a write-transaction is open on [database connection] D when the ** [sqlite3_db_cacheflush(D)] interface invoked, any dirty ** pages in the pager-cache that are not currently in use are written out ** to disk. A dirty page may be in use if a database cursor created by an ** active SQL statement is reading from it, or if it is page 1 of a database ** file (page 1 is always "in use"). ^The [sqlite3_db_cacheflush(D)] ** interface flushes caches for all schemas - "main", "temp", and ** any [attached] databases. ** ** ^If this function needs to obtain extra database locks before dirty pages ** can be flushed to disk, it does so. ^If those locks cannot be obtained ** immediately and there is a busy-handler callback configured, it is invoked ** in the usual manner. ^If the required lock still cannot be obtained, then ** the database is skipped and an attempt made to flush any dirty pages ** belonging to the next (if any) database. ^If any databases are skipped ** because locks cannot be obtained, but no other error occurs, this ** function returns SQLITE_BUSY. ** ** ^If any other error occurs while flushing dirty pages to disk (for ** example an IO error or out-of-memory condition), then processing is ** abandoned and an SQLite [error code] is returned to the caller immediately. ** ** ^Otherwise, if no error occurs, [sqlite3_db_cacheflush()] returns SQLITE_OK. ** ** ^This function does not set the database handle error code or message ** returned by the [sqlite3_errcode()] and [sqlite3_errmsg()] functions. */ int sqlite3_db_cacheflush(sqlite3*); /* ** CAPI3REF: Database Snapshot ** KEYWORDS: {snapshot} ** EXPERIMENTAL ** ** An instance of the snapshot object records the state of a [WAL mode] ** database for some specific point in history. ** ** In [WAL mode], multiple [database connections] that are open on the ** same database file can each be reading a different historical version ** of the database file. When a [database connection] begins a read ** transaction, that connection sees an unchanging copy of the database ** as it existed for the point in time when the transaction first started. ** Subsequent changes to the database from other connections are not seen ** by the reader until a new read transaction is started. ** ** The sqlite3_snapshot object records state information about an historical ** version of the database file so that it is possible to later open a new read ** transaction that sees that historical version of the database rather than ** the most recent version. ** ** The constructor for this object is [sqlite3_snapshot_get()]. The ** [sqlite3_snapshot_open()] method causes a fresh read transaction to refer ** to an historical snapshot (if possible). The destructor for ** sqlite3_snapshot objects is [sqlite3_snapshot_free()]. */ typedef struct sqlite3_snapshot sqlite3_snapshot; /* ** CAPI3REF: Record A Database Snapshot ** EXPERIMENTAL ** ** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a ** new [sqlite3_snapshot] object that records the current state of ** schema S in database connection D. ^On success, the ** [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly ** created [sqlite3_snapshot] object into *P and returns SQLITE_OK. ** ^If schema S of [database connection] D is not a [WAL mode] database ** that is in a read transaction, then [sqlite3_snapshot_get(D,S,P)] ** leaves the *P value unchanged and returns an appropriate [error code]. ** ** The [sqlite3_snapshot] object returned from a successful call to ** [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()] ** to avoid a memory leak. */ SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(sqlite3*,const char*,sqlite3_snapshot **ppSnapshot); /* ** CAPI3REF: Start a read transaction on an historical snapshot ** EXPERIMENTAL ** ** ^The [sqlite3_snapshot_open(D,S,P)] interface attempts to move the ** read transaction that is currently open on schema S of ** [database connection] D so that it refers to historical [snapshot] P. ** ^The [sqlite3_snapshot_open()] interface returns SQLITE_OK on success ** or an appropriate [error code] if it fails. ** ** ^In order to succeed, a call to [sqlite3_snapshot_open(D,S,P)] must be ** the first operation, apart from other sqlite3_snapshot_open() calls, ** following the [BEGIN] that starts a new read transaction. ** ^A [snapshot] will fail to open if it has been overwritten by a ** [checkpoint]. */ SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(sqlite3*,const char*,sqlite3_snapshot*); /* ** CAPI3REF: Destroy a snapshot ** EXPERIMENTAL ** ** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P. ** The application must eventually free every [sqlite3_snapshot] object ** using this routine to avoid a memory leak. */ SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*); /* ** Undo the hack that converts floating point types to integer for ** builds on processors without floating point support. */ #ifdef SQLITE_OMIT_FLOATING_POINT # undef double #endif #ifdef __cplusplus } /* End of the 'extern "C"' block */ #endif #endif /* _SQLITE3_H_ */ |
Changes to src/wal.c.
︙ | ︙ | |||
3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 | ** WAL module is using shared-memory, return false. */ int sqlite3WalHeapMemory(Wal *pWal){ return (pWal && pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ); } #ifdef SQLITE_ENABLE_SNAPSHOT int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot){ int rc = SQLITE_OK; WalIndexHdr *pRet; assert( pWal->readLock>=0 && pWal->writeLock==0 ); pRet = (WalIndexHdr*)sqlite3_malloc(sizeof(WalIndexHdr)); if( pRet==0 ){ rc = SQLITE_NOMEM; }else{ memcpy(pRet, &pWal->hdr, sizeof(WalIndexHdr)); *ppSnapshot = (sqlite3_snapshot*)pRet; } return rc; } void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot){ pWal->pSnapshot = (WalIndexHdr*)pSnapshot; } #endif /* SQLITE_ENABLE_SNAPSHOT */ #ifdef SQLITE_ENABLE_ZIPVFS /* | > > > > > > | 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 | ** WAL module is using shared-memory, return false. */ int sqlite3WalHeapMemory(Wal *pWal){ return (pWal && pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ); } #ifdef SQLITE_ENABLE_SNAPSHOT /* Create a snapshot object. The content of a snapshot is opaque to ** every other subsystem, so the WAL module can put whatever it needs ** in the object. */ int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot){ int rc = SQLITE_OK; WalIndexHdr *pRet; assert( pWal->readLock>=0 && pWal->writeLock==0 ); pRet = (WalIndexHdr*)sqlite3_malloc(sizeof(WalIndexHdr)); if( pRet==0 ){ rc = SQLITE_NOMEM; }else{ memcpy(pRet, &pWal->hdr, sizeof(WalIndexHdr)); *ppSnapshot = (sqlite3_snapshot*)pRet; } return rc; } /* Try to open on pSnapshot when the next read-transaction starts */ void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot){ pWal->pSnapshot = (WalIndexHdr*)pSnapshot; } #endif /* SQLITE_ENABLE_SNAPSHOT */ #ifdef SQLITE_ENABLE_ZIPVFS /* |
︙ | ︙ |