Make SQLITE_DIRECT_OVERFLOW_READ work for in WAL mode as long as the page

being read is not in the the -wal file.

FossilOrigin-Name: 9879be1899adf5634f551a2077b15ccb1133e4e3

manifest

@@ -1,5 +1,5 @@
-C Enhancements\sto\sthe\skvtest\sutility\sprogram.\s\sAdd\sthe\s--jmode\soption.\s\nImproved\soutput\sformatting.
-D 2017-01-26T01:54:39.591
+C Make\sSQLITE_DIRECT_OVERFLOW_READ\swork\sfor\sin\sWAL\smode\sas\slong\sas\sthe\spage\nbeing\sread\sis\snot\sin\sthe\sthe\s-wal\sfile.
+D 2017-01-26T02:26:02.936
 F Makefile.in 5f415e7867296d678fed2e6779aea10c1318b4bc
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc b8ca53350ae545e3562403d5da2a69cec79308da
@@ -333,7 +333,7 @@ F src/auth.c 930b376a9c56998557367e6f7f8aaeac82a2a792
 F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 0e9ce2d56159b89b9bc8e197e023ee11e39ff8ca
-F src/btree.c f1b36bcfb1f9532ce64fe534153f11b8e2595d8b
+F src/btree.c 4a4ae5fd82ee576b85163277610d8b8174831f16
 F src/btree.h e6d352808956ec163a17f832193a3e198b3fb0ac
 F src/btreeInt.h 10c4b77c2fb399580babbcc7cf652ac10dba796e
 F src/build.c 9e799f1edd910dfa8a0bc29bd390d35d310596af
@@ -377,8 +377,8 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c 30e2c43e4955db990e5b5a81e901f8aa74cc8820
 F src/os_win.c cf90abd4e50d9f56d2c20ce8e005aff55d7bd8e9
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
-F src/pager.c 9dc72d23eebbdf992bd69f2ab954d0d3a27c7340
-F src/pager.h d1e944291030351f362a0a7da9b5c3e34e603e39
+F src/pager.c ff1232b3088a39806035ecfac4fffeb22717d80b
+F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
 F src/parse.y 29153738a7322054359320eb00b5a4cd44389f20
 F src/pcache.c 51070ec9b8251bbf9c6ea3d35fd96a458752929e
 F src/pcache.h 2cedcd8407eb23017d92790b112186886e179490
@@ -1547,7 +1547,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 50e60cb44fd3687dde5551d02bad60c323beaabc
-R 6c49e01bee6ced9ad603e50cc8404852
+P 62a4851ccf88837d1c16dae8204f7f264e80e3c9
+R 5def997b16301f95d47461ef6a1c2e30
 U drh
-Z 5b3363ef063097392f2b7107d7fe03e8
+Z c8beae43adff961172e88276d51d2aaf

manifest.uuid

@@ -1 +1 @@
-62a4851ccf88837d1c16dae8204f7f264e80e3c9
+9879be1899adf5634f551a2077b15ccb1133e4e3

src/btree.c

@@ -4593,7 +4593,7 @@ static int accessPayload(
         **   2) data is required from the start of this overflow page, and
         **   3) the database is file-backed, and
         **   4) there is no open write-transaction, and
-        **   5) the database is not a WAL database,
+        **   5) the page is not in the WAL file
         **   6) all data from the page is being read.
         **   7) at least 4 bytes have already been read into the output buffer 
         **
@@ -4606,7 +4606,7 @@ static int accessPayload(
          && (bEnd || a==ovflSize)                              /* (6) */
          && pBt->inTransaction==TRANS_READ                     /* (4) */
          && (fd = sqlite3PagerFile(pBt->pPager))->pMethods     /* (3) */
-         && 0==sqlite3PagerUseWal(pBt->pPager)                 /* (5) */
+         && 0==sqlite3PagerUseWal(pBt->pPager, nextPage)       /* (5) */
          && &pBuf[-4]>=pBufStart                               /* (7) */
         ){
           u8 aSave[4];

src/pager.c

@@ -814,14 +814,20 @@ static const unsigned char aJournalMagic[] = {
 #define isOpen(pFd) ((pFd)->pMethods!=0)
 
 /*
-** Return true if this pager uses a write-ahead log instead of the usual
-** rollback journal. Otherwise false.
+** Return true if this pager uses a write-ahead log to read page pgno.
+** Return false if the pager reads pgno directly from the database.
 */
-#ifndef SQLITE_OMIT_WAL
-int sqlite3PagerUseWal(Pager *pPager){
-  return (pPager->pWal!=0);
+#if !defined(SQLITE_OMIT_WAL) && defined(SQLITE_DIRECT_OVERFLOW_READ)
+int sqlite3PagerUseWal(Pager *pPager, Pgno pgno){
+  u32 iRead = 0;
+  int rc;
+  if( pPager->pWal==0 ) return 0;
+  rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iRead);
+  return rc || iRead;
 }
-# define pagerUseWal(x) sqlite3PagerUseWal(x)
+#endif
+#ifndef SQLITE_OMIT_WAL
+# define pagerUseWal(x) ((x)->pWal!=0)
 #else
 # define pagerUseWal(x) 0
 # define pagerRollbackWal(x) 0

src/pager.h

@@ -178,14 +178,16 @@ int sqlite3PagerSharedLock(Pager *pPager);
   int sqlite3PagerWalCallback(Pager *pPager);
   int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
   int sqlite3PagerCloseWal(Pager *pPager, sqlite3*);
-  int sqlite3PagerUseWal(Pager *pPager);
+# ifdef SQLITE_DIRECT_OVERFLOW_READ
+  int sqlite3PagerUseWal(Pager *pPager, Pgno);
+# endif
 # ifdef SQLITE_ENABLE_SNAPSHOT
   int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot);
   int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot);
   int sqlite3PagerSnapshotRecover(Pager *pPager);
 # endif
 #else
-# define sqlite3PagerUseWal(x) 0
+# define sqlite3PagerUseWal(x,y) 0
 #endif
 
 #ifdef SQLITE_ENABLE_ZIPVFS