Add the SQLITE_CHECKPOINT_TRUNCATE option.

FossilOrigin-Name: 8e20a43419e46b6b9d1f60ec7ea420bbfb3ef358

diff --git a/manifest b/manifest
index 7f9f9524d0278cd10138b573a0f5b1cc24975714..35fb1bb478432d76977ee50fe2be8a7b829277b3 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Convert\stwo\sunreachable\sbranches\sinto\sassert()\sstatements.
-D 2014-12-02T16:16:47.791
+C Add\sthe\sSQLITE_CHECKPOINT_TRUNCATE\soption.
+D 2014-12-02T19:04:54.595
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in a226317fdf3f4c895fb3cfedc355b4d0868ce1fb
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -195,7 +195,7 @@ F src/journal.c b4124532212b6952f42eb2c12fa3c25701d8ba8d
 F src/legacy.c ba1863ea58c4c840335a84ec276fc2b25e22bc4e
 F src/lempar.c 7274c97d24bb46631e504332ccd3bd1b37841770
 F src/loadext.c de741e66e5ddc1598d904d7289239696e40ed994
-F src/main.c 54d0f4896cebc61ae5f831937464953780fe5346
+F src/main.c 34b895b5ebfc73cd690dcd9ac6d0eecb28ce729f
 F src/malloc.c 740db54387204c9a2eb67c6d98e68b08e9ef4eab
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c faf615aafd8be74a71494dfa027c113ea5c6615f
@@ -222,7 +222,7 @@ F src/parse.y 5dfead8aed90cb0c7c1115898ee2266804daff45
 F src/pcache.c ace1b67632deeaa84859b4c16c27711dfb7db3d4
 F src/pcache.h b44658c9c932d203510279439d891a2a83e12ba8
 F src/pcache1.c facbdd3ecc09c8f750089d941305694301328e98
-F src/pragma.c 3f3e959390a10c0131676f0e307acce372777e0f
+F src/pragma.c d54cdd40b63d608f2d95b7482c710690e3593a73
 F src/prepare.c b7b7bf020bd4c962f7c8aed5a3c542c7dfe9f9c7
 F src/printf.c 9e75a6a0b55bf61cfff7d7e19d89834a1b938236
 F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
@@ -230,7 +230,7 @@ F src/resolve.c 4965007d6497b6a4d7a6d98751cc39712885f952
 F src/rowset.c eccf6af6d620aaa4579bd3b72c1b6395d9e9fa1e
 F src/select.c 428165951748151e87a15295b7357221433e311b
 F src/shell.c 45d9c9bd7cde07845af957f2d849933b990773cf
-F src/sqlite.h.in c63db0117aeb749ca02b6016dbbbccbbbd9a141d
+F src/sqlite.h.in 400bac7dd1294cb902b5eb85feed1689a2623ced
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h 17d487c3c91b0b8c584a32fbeb393f6f795eea7d
 F src/sqliteInt.h c9e95b8fa9aee30d46387735c5be73fa58886e38
@@ -238,7 +238,7 @@ F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
 F src/status.c 81712116e826b0089bb221b018929536b2b5406f
 F src/table.c f142bba7903e93ca8d113a5b8877a108ad1a27dc
 F src/tclsqlite.c 0a874655dd39a9875e39c5d3c464db662171d228
-F src/test1.c a0bce4f47da65b76c80e5f8bf9a5ef174603866a
+F src/test1.c f5d7ecd3dd663b11f35269fd91f7090db0570903
 F src/test2.c 98049e51a17dc62606a99a9eb95ee477f9996712
 F src/test3.c 1c0e5d6f080b8e33c1ce8b3078e7013fdbcd560c
 F src/test4.c 9b32d22f5f150abe23c1830e2057c4037c45b3df
@@ -291,7 +291,7 @@ F src/update.c 3c4ecc282accf12d39edb8d524cf089645e55a13
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
 F src/util.c 3b627daa45c7308c1e36e3dbaa3f9ce7e5c7fa73
 F src/vacuum.c 9b30ec729337dd012ed88d4c292922c8ef9cf00c
-F src/vdbe.c ec1f55acef4864520ca2017b9f0d60c2ac1b8b78
+F src/vdbe.c 60217f3b8ab984b2e2bb9e3965276dd29e5efe5d
 F src/vdbe.h 6fc69d9c5e146302c56e163cb4b31d1ee64a18c3
 F src/vdbeInt.h 9bb69ff2447c34b6ccc58b34ec35b615f86ead78
 F src/vdbeapi.c 07acb615d1e4170e71fc1b0d087f3c53a1ad8e83
@@ -301,7 +301,7 @@ F src/vdbemem.c 31d8eabb0cd78bfeab4e5124c7363c3e9e54db9f
 F src/vdbesort.c 42c166f7ca78cb643c7f4e4bdfa83c59d363d1a6
 F src/vdbetrace.c 7e4222955e07dd707a2f360c0eb73452be1cb010
 F src/vtab.c c08ec66f45919eaa726bf88aa53eb08379d607f9
-F src/wal.c 486e644b3b8aa5ad066f625bc428aa8ff7001405
+F src/wal.c f09818db7ba6e31d7a681eb99f801a7722c731d9
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c c253b95b4ee44b21c406e2a1052636c31ea27804
 F src/where.c a0b16f9d78321cb340a977287d19f826555c7d3b
@@ -1113,7 +1113,7 @@ F test/wal.test 885f32b2b390b30b4aa3dbb0e568f8f78d40f5cc
 F test/wal2.test 1f841d2048080d32f552942e333fd99ce541dada
 F test/wal3.test b22eb662bcbc148c5f6d956eaf94b047f7afe9c0
 F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
-F test/wal5.test 8f888b50f66b78821e61ed0e233ded5de378224b
+F test/wal5.test 174cc1512e304a7dfa28ac30527e28ea02fc37df
 F test/wal6.test 527581f5527bf9c24394991e2be83000aace5f9e
 F test/wal64k.test 163655ecd2cb8afef4737cac2a40fdd2eeaf20b8
 F test/wal7.test 2ae8f427d240099cc4b2dfef63cff44e2a68a1bd
@@ -1223,7 +1223,10 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 0d04f380e1bd17104b3cf76b64d0cfc79a726606
-R 22214da224af1bd07c2ba4ce527797c4
-U drh
-Z 4469ca4ec037115204af98a9b9e41068
+P 61b31e771430f490fc2c4cef55046debc4a5f4f5
+R 837049ab8d5153c1422981d3f48166e4
+T *branch * checkpoint-truncate
+T *sym-checkpoint-truncate *
+T -sym-trunk *
+U dan
+Z ce82007701b4a39f21164e74e2380c4f

diff --git a/manifest.uuid b/manifest.uuid
index fe8f0fdad5cfd0e23f80539da43f1c70c28aed9e..9aff9e9fbc03e95d539b9865abaae5fea8508ca8 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-61b31e771430f490fc2c4cef55046debc4a5f4f5
\ No newline at end of file
+8e20a43419e46b6b9d1f60ec7ea420bbfb3ef358
\ No newline at end of file

diff --git a/src/main.c b/src/main.c
index 1d34b13d6ff077b411f8362b1c8c1558e521b782..9ac3fde733ec059211d2f2c549beba07c3a0b48c 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -1936,10 +1936,11 @@ int sqlite3_wal_checkpoint_v2(
   if( pnLog ) *pnLog = -1;
   if( pnCkpt ) *pnCkpt = -1;
 
-  assert( SQLITE_CHECKPOINT_FULL>SQLITE_CHECKPOINT_PASSIVE );
-  assert( SQLITE_CHECKPOINT_FULL<SQLITE_CHECKPOINT_RESTART );
-  assert( SQLITE_CHECKPOINT_PASSIVE+2==SQLITE_CHECKPOINT_RESTART );
-  if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_RESTART ){
+  assert( SQLITE_CHECKPOINT_PASSIVE==0 );
+  assert( SQLITE_CHECKPOINT_FULL==1 );
+  assert( SQLITE_CHECKPOINT_RESTART==2 );
+  assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
+  if( eMode<SQLITE_CHECKPOINT_PASSIVE || eMode>SQLITE_CHECKPOINT_TRUNCATE ){
     return SQLITE_MISUSE;
   }
 

diff --git a/src/pragma.c b/src/pragma.c
index 543f265ba9ea1ae5e8e0fff897f91f76aa334450..ab9a2836298b7755a5ea2d0c8f93cb0b55f05d1f 100644 (file)
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -2195,7 +2195,7 @@ void sqlite3Pragma(
 
 #ifndef SQLITE_OMIT_WAL
   /*
-  **   PRAGMA [database.]wal_checkpoint = passive|full|restart
+  **   PRAGMA [database.]wal_checkpoint = passive|full|restart|truncate
   **
   ** Checkpoint the database.
   */
@@ -2207,6 +2207,8 @@ void sqlite3Pragma(
         eMode = SQLITE_CHECKPOINT_FULL;
       }else if( sqlite3StrICmp(zRight, "restart")==0 ){
         eMode = SQLITE_CHECKPOINT_RESTART;
+      }else if( sqlite3StrICmp(zRight, "truncate")==0 ){
+        eMode = SQLITE_CHECKPOINT_TRUNCATE;
       }
     }
     sqlite3VdbeSetNumCols(v, 3);

diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index f1b917c3086355c0cc024288874fb1df9377e30e..807c9ee62c999a9e7e587d1e49fb0533b00b0bbf 100644 (file)
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -7291,6 +7291,10 @@ int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
 **   that the next client to write to the database file restarts the log file 
 **   from the beginning. This call blocks database writers while it is running,
 **   but not database readers.
+**
+** <dt>SQLITE_CHECKPOINT_TRUNCATE<dd>
+**   This mode works the same way as SQLITE_CHECKPOINT_RESTART except that,
+**   if successful, it also truncates the log file to zero bytes in size.
 ** </dl>
 **
 ** If pnLog is not NULL, then *pnLog is set to the total number of frames in
@@ -7306,11 +7310,11 @@ int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
 ** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a 
 ** busy-handler configured, it will not be invoked in this case.
 **
-** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive 
-** "writer" lock on the database file. If the writer lock cannot be obtained
-** immediately, and a busy-handler is configured, it is invoked and the writer
-** lock retried until either the busy-handler returns 0 or the lock is
-** successfully obtained. The busy-handler is also invoked while waiting for
+** The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the 
+** exclusive "writer" lock on the database file. If the writer lock cannot be
+** obtained immediately, and a busy-handler is configured, it is invoked and
+** the writer lock retried until either the busy-handler returns 0 or the lock
+** is successfully obtained. The busy-handler is also invoked while waiting for
 ** database readers as described above. If the busy-handler returns 0 before
 ** the writer lock is obtained or while waiting for database readers, the
 ** checkpoint operation proceeds from that point in the same way as 
@@ -7349,9 +7353,10 @@ int sqlite3_wal_checkpoint_v2(
 ** documentation for additional information about the meaning and use of
 ** each of these values.
 */
-#define SQLITE_CHECKPOINT_PASSIVE 0
-#define SQLITE_CHECKPOINT_FULL    1
-#define SQLITE_CHECKPOINT_RESTART 2
+#define SQLITE_CHECKPOINT_PASSIVE  0
+#define SQLITE_CHECKPOINT_FULL     1
+#define SQLITE_CHECKPOINT_RESTART  2
+#define SQLITE_CHECKPOINT_TRUNCATE 3
 
 /*
 ** CAPI3REF: Virtual Table Interface Configuration

diff --git a/src/test1.c b/src/test1.c
index 1c43861547e37af845bc480fb5b20e061fc066a4..be4ad92c11bfe88bf5356714dd3da2c05034c6c0 100644 (file)
--- a/src/test1.c
+++ b/src/test1.c
@@ -5690,10 +5690,11 @@ static int test_wal_checkpoint_v2(
   int nCkpt = -555;
   Tcl_Obj *pRet;
 
-  const char * aMode[] = { "passive", "full", "restart", 0 };
+  const char * aMode[] = { "passive", "full", "restart", "truncate", 0 };
   assert( SQLITE_CHECKPOINT_PASSIVE==0 );
   assert( SQLITE_CHECKPOINT_FULL==1 );
   assert( SQLITE_CHECKPOINT_RESTART==2 );
+  assert( SQLITE_CHECKPOINT_TRUNCATE==3 );
 
   if( objc!=3 && objc!=4 ){
     Tcl_WrongNumArgs(interp, 1, objv, "DB MODE ?NAME?");

diff --git a/src/vdbe.c b/src/vdbe.c
index 822bf80bb8522d93a767582346d33f8d0f089f33..7f661b42b19b393af62c4c4d2a5dcacbfe68a643 100644 (file)
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -5724,6 +5724,7 @@ case OP_Checkpoint: {
   assert( pOp->p2==SQLITE_CHECKPOINT_PASSIVE
        || pOp->p2==SQLITE_CHECKPOINT_FULL
        || pOp->p2==SQLITE_CHECKPOINT_RESTART
+       || pOp->p2==SQLITE_CHECKPOINT_TRUNCATE
   );
   rc = sqlite3Checkpoint(db, pOp->p1, pOp->p2, &aRes[1], &aRes[2]);
   if( rc==SQLITE_BUSY ){

diff --git a/src/wal.c b/src/wal.c
index 3033444b4106035638fdf438fe0dd339e459db7f..849b776743f1c02b6b6f21bf883514e628516052 100644 (file)
--- a/src/wal.c
+++ b/src/wal.c
@@ -1623,6 +1623,34 @@ static int walPagesize(Wal *pWal){
   return (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
 }
 
+/*
+** The following is guaranteed when this function is called:
+**
+**   a) the WRITER lock is held,
+**   b) the entire log file has been checkpointed, and
+**   c) any existing readers are reading exclusively from the database
+**      file - there are no readers that may attempt to read a frame from
+**      the log file.
+**
+** This function updates the shared-memory structures so that the next
+** client to write to the database (which may be this one) does so by
+** writing frames into the start of the log file.
+*/
+static void walRestartHdr(Wal *pWal){
+  volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+  int i;                          /* Loop counter */
+  u32 *aSalt = pWal->hdr.aSalt;   /* Big-endian salt values */
+  pWal->nCkpt++;
+  pWal->hdr.mxFrame = 0;
+  sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
+  sqlite3_randomness(4, &aSalt[1]);
+  walIndexWriteHdr(pWal);
+  pInfo->nBackfill = 0;
+  pInfo->aReadMark[1] = 0;
+  for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+  assert( pInfo->aReadMark[0]==0 );
+}
+
 /*
 ** Copy as much content as we can from the WAL back into the database file
 ** in response to an sqlite3_wal_checkpoint() request or the equivalent.
@@ -1775,19 +1803,34 @@ static int walCheckpoint(
     rc = SQLITE_OK;
   }
 
-  /* If this is an SQLITE_CHECKPOINT_RESTART operation, and the entire wal
-  ** file has been copied into the database file, then block until all
-  ** readers have finished using the wal file. This ensures that the next
-  ** process to write to the database restarts the wal file.
+  /* If this is an SQLITE_CHECKPOINT_RESTART or TRUNCATE operation, and the
+  ** entire wal file has been copied into the database file, then block 
+  ** until all readers have finished using the wal file. This ensures that 
+  ** the next process to write to the database restarts the wal file.
   */
   if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
     assert( pWal->writeLock );
     if( pInfo->nBackfill<pWal->hdr.mxFrame ){
       rc = SQLITE_BUSY;
-    }else if( eMode==SQLITE_CHECKPOINT_RESTART ){
+    }else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
       assert( mxSafeFrame==pWal->hdr.mxFrame );
       rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
       if( rc==SQLITE_OK ){
+        if( eMode==SQLITE_CHECKPOINT_TRUNCATE ){
+          /* If this is a TRUNCATE checkpoint, also truncate the wal file
+          ** to zero bytes in size on disk. 
+          **
+          ** In theory, it might be safe to do this without updating the
+          ** wal-index header in shared memory, as all subsequent reader or
+          ** writer clients should see that the entire log file has been
+          ** checkpointed and behave accordingly. This seems unsafe though,
+          ** as it would leave the system in a state where the contents of
+          ** the wal-index header do not match the contents of the 
+          ** file-system. To avoid this, update the wal-index header to
+          ** indicate that the log file contains zero valid frames.  */
+          walRestartHdr(pWal);
+          rc = sqlite3OsTruncate(pWal->pWalFd, 0);
+        }
         walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
       }
     }
@@ -2573,7 +2616,6 @@ int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
   return rc;
 }
 
-
 /*
 ** This function is called just before writing a set of frames to the log
 ** file (see sqlite3WalFrames()). It checks to see if, instead of appending
@@ -2606,20 +2648,8 @@ static int walRestartLog(Wal *pWal){
         ** In theory it would be Ok to update the cache of the header only
         ** at this point. But updating the actual wal-index header is also
         ** safe and means there is no special case for sqlite3WalUndo()
-        ** to handle if this transaction is rolled back.
-        */
-        int i;                    /* Loop counter */
-        u32 *aSalt = pWal->hdr.aSalt;       /* Big-endian salt values */
-
-        pWal->nCkpt++;
-        pWal->hdr.mxFrame = 0;
-        sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
-        aSalt[1] = salt1;
-        walIndexWriteHdr(pWal);
-        pInfo->nBackfill = 0;
-        pInfo->aReadMark[1] = 0;
-        for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
-        assert( pInfo->aReadMark[0]==0 );
+        ** to handle if this transaction is rolled back.  */
+        walRestartHdr(pWal);
         walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
       }else if( rc!=SQLITE_BUSY ){
         return rc;

diff --git a/test/wal5.test b/test/wal5.test
index 68750f1479d8eb4061a9ead52a6a28c580233103..09c7d76040cca19d2dd3d25745b4be759dfd4b9f 100644 (file)
--- a/test/wal5.test
+++ b/test/wal5.test
@@ -55,7 +55,8 @@ foreach {testprefix do_wal_checkpoint} {
         if {[lsearch {-mode -db} $key]<0} { error "unknown switch: $key" }
       }
 
-      if {$a(-mode)!="restart" && $a(-mode)!="full"} { set a(-mode) passive }
+      set vals {restart full truncate}
+      if {[lsearch -exact $vals $a(-mode)]<0} { set a(-mode) passive }
 
       set cmd [list sqlite3_wal_checkpoint_v2 $dbhandle $a(-mode)]
       if {[info exists a(-db)]} { lappend sql $a(-db) }
@@ -278,6 +279,11 @@ foreach {testprefix do_wal_checkpoint} {
     9   RESTART   2   {1 4 3}   2
     10  RESTART   3   {1 4 4}   3
 
+    11  TRUNCATE  -   {0 0 0}   3
+    12  TRUNCATE  1   {1 3 3}   1
+    13  TRUNCATE  2   {1 4 3}   2
+    14  TRUNCATE  3   {1 4 4}   3
+
   } {
     do_multiclient_test tn {
       setup_and_attach_aux
@@ -348,6 +354,41 @@ foreach {testprefix do_wal_checkpoint} {
 
     do_test 3.$tn.6 { code3 { do_wal_checkpoint db3 } } {0 0 0}
   }
+
+  # Test SQLITE_CHECKPOINT_TRUNCATE.
+  #
+  do_multiclient_test tn {
+
+    code1 $do_wal_checkpoint
+    code2 $do_wal_checkpoint
+    code3 $do_wal_checkpoint
+
+    do_test 3.$tn.1 {
+      sql1 {
+        PRAGMA page_size = 1024;
+        PRAGMA journal_mode = WAL;
+        PRAGMA synchronous = normal;
+        CREATE TABLE t1(x, y);
+        CREATE INDEX i1 ON t1(x, y);
+        INSERT INTO t1 VALUES(1, 2);
+        INSERT INTO t1 VALUES(3, 4);
+      }
+      file size test.db-wal
+    } [wal_file_size 8 1024]
+
+    do_test 3.$tn.2 { do_wal_checkpoint db -mode truncate } {0 0 0}
+    do_test 3.$tn.3 { file size test.db-wal } 0
+
+    do_test 3.$tn.4 {
+      sql2 { SELECT * FROM t1 }
+    } {1 2 3 4}
+
+    do_test 3.$tn.5 {
+      sql2 { INSERT INTO t1 VALUES('a', 'b') }
+      file size test.db-wal
+    } [wal_file_size 2 1024]
+
+  }
 }