Bug 595925 - Use OpenUnsharedDatabase in cookies. r=sdwilsh, a=final+

netwerk/cookie/nsCookieService.cpp

@@ -731,9 +731,10 @@ nsCookieService::TryInitDB(PRBool aDeleteExistingDB)
   }
 
   // open a connection to the cookie database, and only cache our connection
-  // and statements upon success. The connection is opened shared such that
-  // the main and background threads can operate on the db concurrently.
-  rv = mStorageService->OpenDatabase(cookieFile, getter_AddRefs(mDBState->dbConn));
+  // and statements upon success. The connection is opened unshared to eliminate
+  // cache contention between the main and background threads.
+  rv = mStorageService->OpenUnsharedDatabase(cookieFile,
+    getter_AddRefs(mDBState->dbConn));
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Grow cookie db in 512KB increments
@@ -882,9 +883,6 @@ nsCookieService::TryInitDB(PRBool aDeleteExistingDB)
   // make operations on the table asynchronous, for performance
   mDBState->dbConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING("PRAGMA synchronous = OFF"));
 
-  // open in exclusive mode for performance
-  mDBState->dbConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING("PRAGMA locking_mode = EXCLUSIVE"));
-
   // cache frequently used statements (for insertion, deletion, and updating)
   rv = mDBState->dbConn->CreateStatement(NS_LITERAL_CSTRING(
     "INSERT INTO moz_cookies ("
@@ -1559,7 +1557,7 @@ nsCookieService::GetSyncDBConn()
   mDefaultDBState.dbConn->GetDatabaseFile(getter_AddRefs(cookieFile));
   NS_ASSERTION(cookieFile, "no cookie file on connection");
 
-  mStorageService->OpenDatabase(cookieFile,
+  mStorageService->OpenUnsharedDatabase(cookieFile,
     getter_AddRefs(mDefaultDBState.syncConn));
   NS_ASSERTION(mDefaultDBState.syncConn, "can't open sync db connection");
   return mDefaultDBState.syncConn;

storage/public/mozIStorageService.idl

@@ -111,12 +111,9 @@ interface mozIStorageService : nsISupports {
    * Each connection uses its own sqlite cache, which is inefficient, so you
    * should use openDatabase instead of this method unless you need a feature
    * of SQLite that is incompatible with a shared cache, like virtual table
-   * and full text indexing support.
-   *
-   * Consumers should check mozIStorageConnection::connectionReady to ensure
-   * that they can use the database.  If this value is false, it is strongly
-   * recommended that the database be backed up with
-   * mozIStorageConnection::backupDB so user data is not lost.
+   * and full text indexing support. If cache contention is expected, for
+   * instance when operating on a database from multiple threads, using
+   * unshared connections may be a performance win.
    *
    * ==========
    *   DANGER
@@ -131,7 +128,7 @@ interface mozIStorageService : nsISupports {
    * use it only from the thread you created it from.
    *
    * @param aDatabaseFile
-   *        A nsIFile that represents the database that is to be opened..
+   *        A nsIFile that represents the database that is to be opened.
    *
    * @returns a mozIStorageConnection for the requested database file.
    *