Add a new assert() statement to the snapshot-specific part of sqlite3WalBeginReadTrans().

FossilOrigin-Name: d8a12023be32bdc6df18b0a5f38b917799854342

manifest

@@ -1,5 +1,5 @@
-C Simplified\salignment\sconstraints\sin\sthe\smemory\sreuse\slogic\sof\nsqlite3VdbeMakeReady().
-D 2015-12-11T13:51:02.921
+C Add\sa\snew\sassert()\sstatement\sto\sthe\ssnapshot-specific\spart\sof\ssqlite3WalBeginReadTrans().
+D 2015-12-11T14:59:49.435
 F Makefile.in 28bcd6149e050dff35d4dcfd97e890cd387a499d
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc e8fdca1cb89a1b58b5f4d3a130ea9a3d28cb314d
@@ -415,7 +415,7 @@ F src/vdbesort.c a7ec02da4494c59dfd071126dd3726be5a11459d
 F src/vdbetrace.c 8befe829faff6d9e6f6e4dee5a7d3f85cc85f1a0
 F src/vtab.c 2a8b44aa372c33f6154208e7a7f6c44254549806
 F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
-F src/wal.c cb709aa42fc11b1ea92a00c8c7e6214de0995fa3
+F src/wal.c 974928c988681c5157202c79dd9f26afaa7b5086
 F src/wal.h 907943dfdef10b583e81906679a347e0ec6f1b1b
 F src/walker.c 2e14d17f592d176b6dc879c33fbdec4fbccaa2ba
 F src/where.c b18edbb9e5afabb77f4f27550c471c5c824e0fe7
@@ -1410,7 +1410,7 @@ F tool/vdbe_profile.tcl 246d0da094856d72d2c12efec03250d71639d19f
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 9b124a5a310aec0145495c9980bc0c1308fcca02
-R 8b7bf5c5d9b6c5d6524021fe34935458
-U drh
-Z 8b682652b257be08de396beec767150c
+P e998513e442ce1206b12dc28bdc996d7b5f9f94d
+R a4790a1ff73d4c37057dc2f097901685
+U dan
+Z 708cca6403fc05264746d6ebc901db59

manifest.uuid

@@ -1 +1 @@
-e998513e442ce1206b12dc28bdc996d7b5f9f94d
+d8a12023be32bdc6df18b0a5f38b917799854342

src/wal.c

@@ -2442,6 +2442,7 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
         if( !memcmp(pSnapshot->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
          && pSnapshot->mxFrame>=pInfo->nBackfillAttempted
         ){
+          assert( pWal->readLock>0 );
           memcpy(&pWal->hdr, pSnapshot, sizeof(WalIndexHdr));
           *pChanged = bChanged;
         }else{