LCOV - code coverage report
Current view: directory - objdir/dist/include/mozilla/storage - StatementCache.h (source / functions) Found Hit Coverage
Test: app.info Lines: 45 34 75.6 %
Date: 2012-06-02 Functions: 18 18 100.0 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
       2                 :  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
       3                 :  * ***** BEGIN LICENSE BLOCK *****
       4                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       5                 :  *
       6                 :  * The contents of this file are subject to the Mozilla Public License Version
       7                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       8                 :  * the License. You may obtain a copy of the License at
       9                 :  * http://www.mozilla.org/MPL/
      10                 :  *
      11                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      12                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      13                 :  * for the specific language governing rights and limitations under the
      14                 :  * License.
      15                 :  *
      16                 :  * The Original Code is the mozStorage statement cache.
      17                 :  *
      18                 :  * The Initial Developer of the Original Code is
      19                 :  * the Mozilla Foundation.
      20                 :  * Portions created by the Initial Developer are Copyright (C) 2010
      21                 :  * the Initial Developer. All Rights Reserved.
      22                 :  *
      23                 :  * Contributor(s):
      24                 :  *   Shawn Wilsher <me@shawnwilsher.com>
      25                 :  *
      26                 :  * Alternatively, the contents of this file may be used under the terms of
      27                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      28                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      29                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      30                 :  * of those above. If you wish to allow use of your version of this file only
      31                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      32                 :  * use your version of this file under the terms of the MPL, indicate your
      33                 :  * decision by deleting the provisions above and replace them with the notice
      34                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      35                 :  * the provisions above, a recipient may use your version of this file under
      36                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      37                 :  *
      38                 :  * ***** END LICENSE BLOCK ***** */
      39                 : 
      40                 : #ifndef mozilla_storage_StatementCache_h
      41                 : #define mozilla_storage_StatementCache_h
      42                 : 
      43                 : #include "mozIStorageConnection.h"
      44                 : #include "mozIStorageStatement.h"
      45                 : #include "mozIStorageAsyncStatement.h"
      46                 : 
      47                 : #include "nsAutoPtr.h"
      48                 : #include "nsHashKeys.h"
      49                 : #include "nsInterfaceHashtable.h"
      50                 : 
      51                 : namespace mozilla {
      52                 : namespace storage {
      53                 : 
      54                 : /**
      55                 :  * Class used to cache statements (mozIStorageStatement or
      56                 :  * mozIStorageAsyncStatement).
      57                 :  */
      58                 : template<typename StatementType>
      59             960 : class StatementCache {
      60                 : public:
      61                 :   /**
      62                 :    * Constructor for the cache.
      63                 :    *
      64                 :    * @note a connection can have more than one cache.
      65                 :    *
      66                 :    * @param aConnection
      67                 :    *        A reference to the nsCOMPtr for the connection this cache is to be
      68                 :    *        used for.  This nsCOMPtr must at least live as long as this class,
      69                 :    *        otherwise crashes will happen.
      70                 :    */
      71             960 :   StatementCache(nsCOMPtr<mozIStorageConnection>& aConnection)
      72             960 :   : mConnection(aConnection)
      73                 :   {
      74             960 :     if (!mCachedStatements.Init()) {
      75               0 :       NS_ERROR("Out of memory!?");
      76                 :     }
      77             960 :   }
      78                 : 
      79                 :   /**
      80                 :    * Obtains a cached statement.  If this statement is not yet created, it will
      81                 :    * be created and stored for later use.
      82                 :    *
      83                 :    * @param aQuery
      84                 :    *        The SQL string (either a const char [] or nsACString) to get a
      85                 :    *        cached query for.
      86                 :    * @return the cached statement, or null upon error.
      87                 :    */
      88                 :   inline
      89                 :   already_AddRefed<StatementType>
      90           58912 :   GetCachedStatement(const nsACString& aQuery)
      91                 :   {
      92          117824 :     nsCOMPtr<StatementType> stmt;
      93           58912 :     if (!mCachedStatements.Get(aQuery, getter_AddRefs(stmt))) {
      94            4299 :       stmt = CreateStatement(aQuery);
      95            4299 :       NS_ENSURE_TRUE(stmt, nsnull);
      96                 : 
      97            4299 :       if (!mCachedStatements.Put(aQuery, stmt)) {
      98               0 :         NS_ERROR("Out of memory!?");
      99                 :       }
     100                 :     }
     101           58912 :     return stmt.forget();
     102                 :   }
     103                 : 
     104                 :   template<int N>
     105                 :   NS_ALWAYS_INLINE already_AddRefed<StatementType>
     106                 :   GetCachedStatement(const char (&aQuery)[N])
     107                 :   {
     108             422 :     nsDependentCString query(aQuery, N - 1);
     109             211 :     return GetCachedStatement(query);
     110                 :   }
     111                 : 
     112                 :   /**
     113                 :    * Finalizes all cached statements so the database can be safely closed.  The
     114                 :    * behavior of this cache is unspecified after this method is called.
     115                 :    */
     116                 :   inline
     117                 :   void
     118             873 :   FinalizeStatements()
     119                 :   {
     120             873 :     (void)mCachedStatements.Enumerate(FinalizeCachedStatements, NULL);
     121                 : 
     122                 :     // Clear the cache at this time too!
     123             873 :     (void)mCachedStatements.Clear();
     124             873 :   }
     125                 : 
     126                 : private:
     127                 :   inline
     128                 :   already_AddRefed<StatementType>
     129                 :   CreateStatement(const nsACString& aQuery);
     130                 :   static
     131                 :   PLDHashOperator
     132            4295 :   FinalizeCachedStatements(const nsACString& aKey,
     133                 :                            nsCOMPtr<StatementType>& aStatement,
     134                 :                            void*)
     135                 :   {
     136            4295 :     (void)aStatement->Finalize();
     137            4295 :     return PL_DHASH_NEXT;
     138                 :   }
     139                 : 
     140                 :   nsInterfaceHashtable<nsCStringHashKey, StatementType> mCachedStatements;
     141                 :   nsCOMPtr<mozIStorageConnection>& mConnection;
     142                 : };
     143                 : 
     144                 : template< >
     145                 : inline
     146                 : already_AddRefed<mozIStorageStatement>
     147            3457 : StatementCache<mozIStorageStatement>::CreateStatement(const nsACString& aQuery)
     148                 : {
     149            3457 :   NS_ENSURE_TRUE(mConnection, nsnull);
     150                 : 
     151            6914 :   nsCOMPtr<mozIStorageStatement> stmt;
     152            3457 :   nsresult rv = mConnection->CreateStatement(aQuery, getter_AddRefs(stmt));
     153            3457 :   if (NS_FAILED(rv)) {
     154               0 :     nsCString error;
     155               0 :     error.AppendLiteral("The statement '");
     156               0 :     error.Append(aQuery);
     157               0 :     error.AppendLiteral("' failed to compile with the error message '");
     158               0 :     nsCString msg;
     159               0 :     (void)mConnection->GetLastErrorString(msg);
     160               0 :     error.Append(msg);
     161               0 :     error.AppendLiteral("'.");
     162               0 :     NS_ERROR(error.get());
     163                 :   }
     164            3457 :   NS_ENSURE_SUCCESS(rv, nsnull);
     165                 : 
     166            3457 :   return stmt.forget();
     167                 : }
     168                 : 
     169                 : template< >
     170                 : inline
     171                 : already_AddRefed<mozIStorageAsyncStatement>
     172             842 : StatementCache<mozIStorageAsyncStatement>::CreateStatement(const nsACString& aQuery)
     173                 : {
     174             842 :   NS_ENSURE_TRUE(mConnection, nsnull);
     175                 : 
     176            1684 :   nsCOMPtr<mozIStorageAsyncStatement> stmt;
     177             842 :   nsresult rv = mConnection->CreateAsyncStatement(aQuery, getter_AddRefs(stmt));
     178             842 :   NS_ENSURE_SUCCESS(rv, nsnull);
     179                 : 
     180             842 :   return stmt.forget();
     181                 : }
     182                 : 
     183                 : } // namespace storage
     184                 : } // namespace mozilla
     185                 : 
     186                 : #endif // mozilla_storage_StatementCache_h

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