diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/sqlite.h.in | 27 | ||||
| -rw-r--r-- | src/test1.c | 26 | ||||
| -rw-r--r-- | src/wal.c | 17 |
3 files changed, 70 insertions, 0 deletions
diff --git a/src/sqlite.h.in b/src/sqlite.h.in index 33b6d1f5e..d50d826b4 100644 --- a/src/sqlite.h.in +++ b/src/sqlite.h.in @@ -8129,6 +8129,33 @@ SQLITE_EXPERIMENTAL int sqlite3_snapshot_open( SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*); /* +** CAPI3REF: Compare the ages of two snapshot handles. +** EXPERIMENTAL +** +** The sqlite3_snapshot_cmp(P1, P2) interface is used to compare the ages +** of two valid snapshot handles. +** +** If the two snapshot handles are not associated with the same database +** file, the result of the comparison is undefined. +** +** Additionally, the result of the comparison is only valid if both of the +** snapshot handles were obtained by calling sqlite3_snapshot_get() since the +** last time the wal file was deleted. The wal file is deleted when the +** database is changed back to rollback mode or when the number of database +** clients drops to zero. If either snapshot handle was obtained before the +** wal file was last deleted, the value returned by this function +** is undefined. +** +** Otherwise, this API returns a negative value if P1 refers to an older +** snapshot than P2, zero if the two handles refer to the same database +** snapshot, and a positive value if P1 is a newer snapshot than P2. +*/ +SQLITE_EXPERIMENTAL int sqlite3_snapshot_cmp( + sqlite3_snapshot *p1, + sqlite3_snapshot *p2 +); + +/* ** Undo the hack that converts floating point types to integer for ** builds on processors without floating point support. */ diff --git a/src/test1.c b/src/test1.c index ead9bd47b..0c5af822c 100644 --- a/src/test1.c +++ b/src/test1.c @@ -2359,6 +2359,31 @@ static int test_snapshot_free( } #endif /* SQLITE_ENABLE_SNAPSHOT */ +#ifdef SQLITE_ENABLE_SNAPSHOT +/* +** Usage: sqlite3_snapshot_cmp SNAPSHOT1 SNAPSHOT2 +*/ +static int test_snapshot_cmp( + void * clientData, + Tcl_Interp *interp, + int objc, + Tcl_Obj *CONST objv[] +){ + int res; + sqlite3_snapshot *p1; + sqlite3_snapshot *p2; + if( objc!=3 ){ + Tcl_WrongNumArgs(interp, 1, objv, "SNAPSHOT1 SNAPSHOT2"); + return TCL_ERROR; + } + p1 = (sqlite3_snapshot*)sqlite3TestTextToPtr(Tcl_GetString(objv[1])); + p2 = (sqlite3_snapshot*)sqlite3TestTextToPtr(Tcl_GetString(objv[2])); + res = sqlite3_snapshot_cmp(p1, p2); + Tcl_SetObjResult(interp, Tcl_NewIntObj(res)); + return TCL_OK; +} +#endif /* SQLITE_ENABLE_SNAPSHOT */ + /* ** Usage: sqlite3_next_stmt DB STMT ** @@ -7249,6 +7274,7 @@ int Sqlitetest1_Init(Tcl_Interp *interp){ { "sqlite3_snapshot_get", test_snapshot_get, 0 }, { "sqlite3_snapshot_open", test_snapshot_open, 0 }, { "sqlite3_snapshot_free", test_snapshot_free, 0 }, + { "sqlite3_snapshot_cmp", test_snapshot_cmp, 0 }, #endif }; static int bitmask_size = sizeof(Bitmask)*8; @@ -3399,6 +3399,23 @@ int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot){ void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot){ pWal->pSnapshot = (WalIndexHdr*)pSnapshot; } + +/* +** Return a +ve value if snapshot p1 is newer than p2. A -ve value if +** p1 is older than p2 and zero if p1 and p2 are the same snapshot. +*/ +int sqlite3_snapshot_cmp(sqlite3_snapshot *p1, sqlite3_snapshot *p2){ + WalIndexHdr *pHdr1 = (WalIndexHdr*)p1; + WalIndexHdr *pHdr2 = (WalIndexHdr*)p2; + + /* aSalt[0] is a copy of the value stored in the wal file header. It + ** is incremented each time the wal file is restarted. */ + if( pHdr1->aSalt[0]<pHdr2->aSalt[0] ) return -1; + if( pHdr1->aSalt[0]>pHdr2->aSalt[0] ) return +1; + if( pHdr1->mxFrame<pHdr2->mxFrame ) return -1; + if( pHdr1->mxFrame>pHdr2->mxFrame ) return +1; + return 0; +} #endif /* SQLITE_ENABLE_SNAPSHOT */ #ifdef SQLITE_ENABLE_ZIPVFS |