useWal           51042 ext/sqlite3/libsqlite/sqlite3.c static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
useWal           51078 ext/sqlite3/libsqlite/sqlite3.c   if( !useWal ){
useWal           51111 ext/sqlite3/libsqlite/sqlite3.c   if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame ){