Merge the experimental UNDELETABLE_WHEN_OPEN optimization into the trunk.

FossilOrigin-Name: ee0acef1faffd480fd2136f81fb2b6f6a17b5388

1 files changed, 30 insertions, 8 deletions

diff --git a/src/pager.c b/src/pager.c
index c875dd9df..a5377d4c3 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -1219,12 +1219,24 @@ static int pagerUseWal(Pager *pPager){
 static void pager_unlock(Pager *pPager){
   if( !pPager->exclusiveMode ){
     int rc = SQLITE_OK;          /* Return code */
+    int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
 
     /* Always close the journal file when dropping the database lock.
     ** Otherwise, another connection with journal_mode=delete might
     ** delete the file out from under us.
     */
-    sqlite3OsClose(pPager->jfd);
+    assert( (PAGER_JOURNALMODE_MEMORY   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_OFF      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_WAL      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_DELETE   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
+    assert( (PAGER_JOURNALMODE_PERSIST  & 5)==1 );
+    if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
+     || 1!=(pPager->journalMode & 5)
+    ){
+      sqlite3OsClose(pPager->jfd);
+    }
+
     sqlite3BitvecDestroy(pPager->pInJournal);
     pPager->pInJournal = 0;
     releaseAllSavepoints(pPager);
@@ -3115,6 +3127,7 @@ int sqlite3PagerClose(Pager *pPager){
   enable_simulated_io_errors();
   PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
   IOTRACE(("CLOSE %p\n", pPager))
+  sqlite3OsClose(pPager->jfd);
   sqlite3OsClose(pPager->fd);
   sqlite3PageFree(pTmp);
   sqlite3PcacheClose(pPager->pPCache);
@@ -3908,17 +3921,22 @@ int sqlite3PagerOpen(
 */
 static int hasHotJournal(Pager *pPager, int *pExists){
   sqlite3_vfs * const pVfs = pPager->pVfs;
-  int rc;                       /* Return code */
-  int exists;                   /* True if a journal file is present */
+  int rc = SQLITE_OK;           /* Return code */
+  int exists = 1;               /* True if a journal file is present */
+  int jrnlOpen = !!isOpen(pPager->jfd);
 
   assert( pPager!=0 );
   assert( pPager->useJournal );
   assert( isOpen(pPager->fd) );
-  assert( !isOpen(pPager->jfd) );
   assert( pPager->state <= PAGER_SHARED );
+  assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
+    SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
+  ));
 
   *pExists = 0;
-  rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
+  if( !jrnlOpen ){
+    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
+  }
   if( rc==SQLITE_OK && exists ){
     int locked;                 /* True if some process holds a RESERVED lock */
 
@@ -3956,15 +3974,19 @@ static int hasHotJournal(Pager *pPager, int *pExists){
           ** If there is, then we consider this journal to be hot. If not, 
           ** it can be ignored.
           */
-          int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
-          rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
+          if( !jrnlOpen ){
+            int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
+            rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
+          }
           if( rc==SQLITE_OK ){
             u8 first = 0;
             rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
             if( rc==SQLITE_IOERR_SHORT_READ ){
               rc = SQLITE_OK;
             }
-            sqlite3OsClose(pPager->jfd);
+            if( !jrnlOpen ){
+              sqlite3OsClose(pPager->jfd);
+            }
             *pExists = (first!=0);
           }else if( rc==SQLITE_CANTOPEN ){
             /* If we cannot open the rollback journal file in order to see if