Ensure that there is always at least one aReadMark slot usable by an unprivileged reader while a checkpoint is running. Also, if one or more transactions are recovered from a log file, initialize one of the aReadMark slots to contain mxFrame as part of the recovery process.

FossilOrigin-Name: e4163596339c2166f9c4356ab824fff8bda8d0b0

manifest

@@ -1,5 +1,5 @@
-C Amplification\sof\sa\scomment\sin\swal.c.\s\sChange\sthe\saReadMark[]\sprocessing\sso\nthat\sone\sread\smark\sis\sleft\sat\szero\swhen\sa\sWAL\sresets.
+C Ensure\sthat\sthere\sis\salways\sat\sleast\sone\saReadMark\sslot\susable\sby\san\sunprivileged\sreader\swhile\sa\scheckpoint\sis\srunning.\sAlso,\sif\sone\sor\smore\stransactions\sare\srecovered\sfrom\sa\slog\sfile,\sinitialize\sone\sof\sthe\saReadMark\sslots\sto\scontain\smxFrame\sas\spart\sof\sthe\srecovery\sprocess.
-D 2012-07-17T02:56:05.199
+D 2012-07-17T14:37:12.494
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 8f6d858bf3df9978ba43df19985146a1173025e4
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -227,7 +227,7 @@ F src/test_superlock.c 2b97936ca127d13962c3605dbc9a4ef269c424cd
 F src/test_syscall.c a992d8c80ea91fbf21fb2dd570db40e77dd7e6ae
 F src/test_tclvar.c f4dc67d5f780707210d6bb0eb6016a431c04c7fa
 F src/test_thread.c e286f2173563f2a1747c24bcda6b9d030bf4f4e4
-F src/test_vfs.c 9d934e111021d56c629efc73a796648c9519ad12
+F src/test_vfs.c da6d0d982b11756c94c1760196355d33d03ff745
 F src/test_vfstrace.c 6b28adb2a0e8ecd0f2e3581482e1f658b11b4067
 F src/test_wholenumber.c 3d2b9ed1505c40ad5c5ca2ad16ae7a289d6cc251
 F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
@@ -247,7 +247,7 @@ F src/vdbemem.c cb55e84b8e2c15704968ee05f0fae25883299b74
 F src/vdbesort.c b25814d385895544ebc8118245c8311ded7f81c9
 F src/vdbetrace.c 79059ebd17b3c8545fab2a24253713e77e4ab392
 F src/vtab.c bb8ea3a26608bb1357538a5d2fc72beba6638998
-F src/wal.c 16345cdccc95e13b493854f1253b8395fcd519fa
+F src/wal.c 9294df6f96aae5909ae1a9b733fd1e1b4736978b
 F src/wal.h 29c197540b19044e6cd73487017e5e47a1d3dac6
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
 F src/where.c 24c7494d8875ead994b4dfe5461340c27fd424ca
@@ -926,8 +926,8 @@ F test/vtab_alter.test 9e374885248f69e251bdaacf480b04a197f125e5
 F test/vtab_err.test 0d4d8eb4def1d053ac7c5050df3024fd47a3fbd8
 F test/vtab_shared.test 82f463886e18d7f8395a4b6167c91815efe54839
 F test/wal.test a040047d7f2b9f34bc4d597964e5e7c09609c635
-F test/wal2.test d5021064bebfc717fe2bf4db2536ea030b76a773
+F test/wal2.test 7ca814723c487de87d945cdc85c9a0fa45fa8de8
-F test/wal3.test 6504bbf348b2d6dfade64a064f1050fd617e8706
+F test/wal3.test b22eb662bcbc148c5f6d956eaf94b047f7afe9c0
 F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
 F test/wal5.test f58ed4b8b542f71c7441da12fbd769d99b362437
 F test/wal6.test 2e3bc767d9c2ce35c47106148d43fcbd072a93b3
@@ -945,7 +945,7 @@ F test/walhook.test ed00a40ba7255da22d6b66433ab61fab16a63483
 F test/walmode.test 4022fe03ae6e830583672caa101f046438a0473c
 F test/walnoshm.test 84ca10c544632a756467336b7c3b864d493ee496
 F test/walpersist.test 8c6b7e3ec1ba91b5e4dc4e0921d6d3f87cd356a6
-F test/walro.test e6bb27762c9f22601cbb8bff6e0acfd124e74b63
+F test/walro.test f183c0003060a64793f9bfafef4c479418ed7fa8
 F test/walshared.test 6dda2293880c300baf5d791c307f653094585761
 F test/walslow.test e7be6d9888f83aa5d3d3c7c08aa9b5c28b93609a
 F test/walthread.test a2ed5270eb695284d4ad27d252517bdc3317ee2a
@@ -1005,7 +1005,7 @@ F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
-P 6f167adf6050632e8c52f9ac4fb5583bcf27c576
+P 8c9ee1d78f99394eef73a177141ca9e1c67e4e07
-R aff021ec3312340384303b11ff294204
+R 21a0c6942de3e9593e3e93f462c443c7
-U drh
+U dan
-Z 0bb1d32f801f3ecf912dcdccb6dd8135
+Z a98d8c358c03bd601d60af308961371e

manifest.uuid

@@ -1 +1 @@
-8c9ee1d78f99394eef73a177141ca9e1c67e4e07
+e4163596339c2166f9c4356ab824fff8bda8d0b0

src/test_vfs.c

@@ -81,6 +81,7 @@ struct Testvfs {
   Tcl_Obj *pScript;               /* Script to execute */
   TestvfsBuffer *pBuffer;         /* List of shared buffers */
   int isNoshm;
+  int isFullshm;
 
   int mask;                       /* Mask controlling [script] and [ioerr] */
 
@@ -760,6 +761,7 @@ static int tvfsShmOpen(sqlite3_file *pFile){
 
   pFd = tvfsGetFd(pFile);
   p = (Testvfs *)pFd->pVfs->pAppData;
+  assert( 0==p->isFullshm );
   assert( pFd->pShmId && pFd->pShm==0 && pFd->pNext==0 );
 
   /* Evaluate the Tcl script: 
@@ -820,6 +822,10 @@ static int tvfsShmMap(
   TestvfsFd *pFd = tvfsGetFd(pFile);
   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
 
+  if( p->isFullshm ){
+    return sqlite3OsShmMap(pFd->pReal, iPage, pgsz, isWrite, pp);
+  }
+
   if( 0==pFd->pShm ){
     rc = tvfsShmOpen(pFile);
     if( rc!=SQLITE_OK ){
@@ -864,6 +870,10 @@ static int tvfsShmLock(
   int nLock;
   char zLock[80];
 
+  if( p->isFullshm ){
+    return sqlite3OsShmLock(pFd->pReal, ofst, n, flags);
+  }
+
   if( p->pScript && p->mask&TESTVFS_SHMLOCK_MASK ){
     sqlite3_snprintf(sizeof(zLock), zLock, "%d %d", ofst, n);
     nLock = (int)strlen(zLock);
@@ -919,6 +929,11 @@ static void tvfsShmBarrier(sqlite3_file *pFile){
   TestvfsFd *pFd = tvfsGetFd(pFile);
   Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);
 
+  if( p->isFullshm ){
+    sqlite3OsShmBarrier(pFd->pReal);
+    return;
+  }
+
   if( p->pScript && p->mask&TESTVFS_SHMBARRIER_MASK ){
     tvfsExecTcl(p, "xShmBarrier", 
         Tcl_NewStringObj(pFd->pShm->zFile, -1), pFd->pShmId, 0
@@ -936,6 +951,10 @@ static int tvfsShmUnmap(
   TestvfsBuffer *pBuffer = pFd->pShm;
   TestvfsFd **ppFd;
 
+  if( p->isFullshm ){
+    return sqlite3OsShmUnmap(pFd->pReal, deleteFlag);
+  }
+
   if( !pBuffer ) return SQLITE_OK;
   assert( pFd->pShmId && pFd->pShm );
 
@@ -1350,6 +1369,7 @@ static int testvfs_cmd(
 
   int i;
   int isNoshm = 0;                /* True if -noshm is passed */
+  int isFullshm = 0;              /* True if -fullshm is passed */
   int isDefault = 0;              /* True if -default is passed */
   int szOsFile = 0;               /* Value passed to -szosfile */
   int mxPathname = -1;            /* Value passed to -mxpathname */
@@ -1365,6 +1385,7 @@ static int testvfs_cmd(
       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isNoshm) ){
         return TCL_ERROR;
       }
+      if( isNoshm ) isFullshm = 0;
     }
     else if( nSwitch>2 && 0==strncmp("-default", zSwitch, nSwitch) ){
       if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isDefault) ){
@@ -1386,6 +1407,12 @@ static int testvfs_cmd(
         return TCL_ERROR;
       }
     }
+    else if( nSwitch>2 && 0==strncmp("-fullshm", zSwitch, nSwitch) ){
+      if( Tcl_GetBooleanFromObj(interp, objv[i+1], &isFullshm) ){
+        return TCL_ERROR;
+      }
+      if( isFullshm ) isNoshm = 0;
+    }
     else{
       goto bad_args;
     }
@@ -1427,6 +1454,7 @@ static int testvfs_cmd(
   pVfs->szOsFile = szOsFile;
   p->pVfs = pVfs;
   p->isNoshm = isNoshm;
+  p->isFullshm = isFullshm;
   p->mask = TESTVFS_ALL_MASK;
 
   sqlite3_vfs_register(pVfs, isDefault);

src/wal.c

@@ -1199,6 +1199,7 @@ finished:
     pInfo->nBackfill = 0;
     pInfo->aReadMark[0] = 0;
     for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+    if( pWal->hdr.mxFrame ) pInfo->aReadMark[1] = pWal->hdr.mxFrame;
 
     /* If more than one frame was recovered from the log file, report an
     ** event via sqlite3_log(). This is to help with identifying performance
@@ -1699,7 +1700,7 @@ static int walCheckpoint(
       assert( y<=pWal->hdr.mxFrame );
       rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
       if( rc==SQLITE_OK ){
-        pInfo->aReadMark[i] = READMARK_NOT_USED;
+        pInfo->aReadMark[i] = (i==1 ? mxSafeFrame : READMARK_NOT_USED);
         walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
       }else if( rc==SQLITE_BUSY ){
         mxSafeFrame = y;

test/wal2.test

@@ -126,9 +126,11 @@ set RECOVER [list                                      \
   {1 7 unlock exclusive} {0 1 unlock exclusive}        \
 ]
 set READ [list                                         \
-  {4 1 lock exclusive} {4 1 unlock exclusive}          \
   {4 1 lock shared}    {4 1 unlock shared}             \
 ]
+set INITSLOT [list                                     \
+  {4 1 lock exclusive} {4 1 unlock exclusive}          \
+]
 
 foreach {tn iInsert res wal_index_hdr_mod wal_locks} "
          2    5   {5 15}    0             {$RECOVER $READ}
@@ -141,7 +143,7 @@ foreach {tn iInsert res wal_index_hdr_mod wal_locks} "
          9   12   {12 78}   7             {$RECOVER $READ}
         10   13   {13 91}   8             {$RECOVER $READ}
         11   14   {14 105}  9             {$RECOVER $READ}
-        12   15   {15 120}  -1            {$READ}
+        12   15   {15 120}  -1            {$INITSLOT $READ}
 " {
 
   do_test wal2-1.$tn.1 {

test/wal3.test

@@ -655,7 +655,7 @@ T filter xShmLock
 T script lock_callback
 
 proc lock_callback {method file handle spec} {
-  if {$spec == "4 1 unlock exclusive"} {
+  if {$spec == "1 7 unlock exclusive"} {
     T filter {}
     set ::r [catchsql { SELECT * FROM b } db2]
   }

test/walro.test

@@ -163,6 +163,131 @@ do_multiclient_test tn {
   do_test 1.3.2.4 {
     code1 { sqlite3_extended_errcode db } 
   } {SQLITE_READONLY_RECOVERY}
+
+  #-----------------------------------------------------------------------
+  # Test cases 1.4.* check that checkpoints and log wraps don't prevent
+  # read-only connections from reading the database.
+  do_test 1.4.1 {
+    code1 { db close }
+    forcedelete test.db-shm
+    file exists test.db-shm
+  } {0}
+
+  # Open one read-only and one read-write connection. Write some data
+  # and then run a checkpoint using the read-write connection. Then
+  # check the read-only connection can still read.
+  do_test 1.4.2 {
+    code1 { sqlite3 db file:test.db?readonly_shm=1 }
+    code2 { sqlite3 db2 test.db }
+    csql2 { 
+      INSERT INTO t1 VALUES(1, 2);
+      INSERT INTO t1 VALUES(3, 4);
+      INSERT INTO t1 VALUES(5, 6);
+      PRAGMA wal_checkpoint;
+    }
+  } {0 {0 3 3}}
+  do_test 1.4.3 {
+    csql1 { SELECT * FROM t1 }
+  } {0 {a b c d e f g h i j k l 1 2 3 4 5 6}}
+  
+  # Using the read-write connection, open a transaction and write lots
+  # of data - causing a cache spill and a log wrap. Then check that the 
+  # read-only connection can still read the database.
+  do_test 1.4.4.1 {
+    csql2 {
+      PRAGMA cache_size = 10;
+      BEGIN;
+      CREATE TABLE t2(x, y);
+      INSERT INTO t2 VALUES('abc', 'xyz');
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      INSERT INTO t2 SELECT x||y, y||x FROM t2;
+    }
+    file size test.db-wal
+  } {147800}
+  do_test 1.4.4.2 {
+    csql1 { SELECT * FROM t1 }
+  } {0 {a b c d e f g h i j k l 1 2 3 4 5 6}}
+  do_test 1.4.4.3 {
+    csql2 COMMIT
+    csql1 { SELECT count(*) FROM t2 }
+  } {0 512}
+  do_test 1.4.5 {
+    code2 { db2 close }
+    code1 { db close }
+  } {}
+}
+
+forcedelete test.db
+
+#-----------------------------------------------------------------------
+# Test cases 2.* check that a read-only connection may read the
+# database file while a checkpoint operation is ongoing.
+#
+do_multiclient_test tn {
+  # Do not run tests with the connections in the same process.
+  #
+  if {$tn==2} continue
+  
+  # Close all connections and delete the database.
+  #
+  code1 { db close  }
+  code2 { db2 close }
+  code3 { db3 close }
+  forcedelete test.db
+  forcedelete walro
+
+  foreach c {code1 code2 code3} {
+    $c {
+      sqlite3_shutdown
+      sqlite3_config_uri 1
+    }
+  }
+  
+  proc tv_hook {x file args} {
+    if {[file tail $file]=="test.db-wal"} {
+      do_test 2.1.2 {
+        code2 { sqlite3 db2 file:test.db?readonly_shm=1 }
+        csql2 { SELECT count(*) FROM t2 }
+      } {0 4}
+      do_test 2.1.3 {
+        code2 { db2 close }
+      } {}
+    } 
+  }
+
+  do_test 2.1.1 {
+    testvfs tv -default 1 -fullshm 1
+    tv script tv_hook
+    tv filter {}
+    code1 { sqlite3 db test.db }
+    csql1 { 
+      PRAGMA journal_mode = WAL;
+      BEGIN;
+        CREATE TABLE t2(x, y);
+        INSERT INTO t2 VALUES('abc', 'xyz');
+        INSERT INTO t2 SELECT x||y, y||x FROM t2;
+        INSERT INTO t2 SELECT x||y, y||x FROM t2;
+      COMMIT;
+    }
+  } {0 wal}
+
+  tv filter xSync
+  set res [csql1 { PRAGMA wal_checkpoint }]
+  do_test 2.1.4 { set res } {0 {0 2 2}}
+
+  do_test 2.1.5 {
+    code1 { db close }
+    code1 { tv delete }
+  } {}
 }
 
 finish_test
+
+