michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef mozilla_storage_StatementCache_h
michael@0: #define mozilla_storage_StatementCache_h
michael@0: 
michael@0: #include "mozIStorageConnection.h"
michael@0: #include "mozIStorageStatement.h"
michael@0: #include "mozIStorageAsyncStatement.h"
michael@0: 
michael@0: #include "nsAutoPtr.h"
michael@0: #include "nsHashKeys.h"
michael@0: #include "nsInterfaceHashtable.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace storage {
michael@0: 
michael@0: /**
michael@0:  * Class used to cache statements (mozIStorageStatement or
michael@0:  * mozIStorageAsyncStatement).
michael@0:  */
michael@0: template<typename StatementType>
michael@0: class StatementCache {
michael@0: public:
michael@0:   /**
michael@0:    * Constructor for the cache.
michael@0:    *
michael@0:    * @note a connection can have more than one cache.
michael@0:    *
michael@0:    * @param aConnection
michael@0:    *        A reference to the nsCOMPtr for the connection this cache is to be
michael@0:    *        used for.  This nsCOMPtr must at least live as long as this class,
michael@0:    *        otherwise crashes will happen.
michael@0:    */
michael@0:   StatementCache(nsCOMPtr<mozIStorageConnection>& aConnection)
michael@0:   : mConnection(aConnection)
michael@0:   {
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Obtains a cached statement.  If this statement is not yet created, it will
michael@0:    * be created and stored for later use.
michael@0:    *
michael@0:    * @param aQuery
michael@0:    *        The SQL string (either a const char [] or nsACString) to get a
michael@0:    *        cached query for.
michael@0:    * @return the cached statement, or null upon error.
michael@0:    */
michael@0:   inline
michael@0:   already_AddRefed<StatementType>
michael@0:   GetCachedStatement(const nsACString& aQuery)
michael@0:   {
michael@0:     nsCOMPtr<StatementType> stmt;
michael@0:     if (!mCachedStatements.Get(aQuery, getter_AddRefs(stmt))) {
michael@0:       stmt = CreateStatement(aQuery);
michael@0:       NS_ENSURE_TRUE(stmt, nullptr);
michael@0: 
michael@0:       mCachedStatements.Put(aQuery, stmt);
michael@0:     }
michael@0:     return stmt.forget();
michael@0:   }
michael@0: 
michael@0:   template<int N>
michael@0:   MOZ_ALWAYS_INLINE already_AddRefed<StatementType>
michael@0:   GetCachedStatement(const char (&aQuery)[N])
michael@0:   {
michael@0:     nsDependentCString query(aQuery, N - 1);
michael@0:     return GetCachedStatement(query);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Finalizes all cached statements so the database can be safely closed.  The
michael@0:    * behavior of this cache is unspecified after this method is called.
michael@0:    */
michael@0:   inline
michael@0:   void
michael@0:   FinalizeStatements()
michael@0:   {
michael@0:     (void)mCachedStatements.Enumerate(FinalizeCachedStatements, nullptr);
michael@0: 
michael@0:     // Clear the cache at this time too!
michael@0:     (void)mCachedStatements.Clear();
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   inline
michael@0:   already_AddRefed<StatementType>
michael@0:   CreateStatement(const nsACString& aQuery);
michael@0:   static
michael@0:   PLDHashOperator
michael@0:   FinalizeCachedStatements(const nsACString& aKey,
michael@0:                            nsCOMPtr<StatementType>& aStatement,
michael@0:                            void*)
michael@0:   {
michael@0:     (void)aStatement->Finalize();
michael@0:     return PL_DHASH_NEXT;
michael@0:   }
michael@0: 
michael@0:   nsInterfaceHashtable<nsCStringHashKey, StatementType> mCachedStatements;
michael@0:   nsCOMPtr<mozIStorageConnection>& mConnection;
michael@0: };
michael@0: 
michael@0: template< >
michael@0: inline
michael@0: already_AddRefed<mozIStorageStatement>
michael@0: StatementCache<mozIStorageStatement>::CreateStatement(const nsACString& aQuery)
michael@0: {
michael@0:   NS_ENSURE_TRUE(mConnection, nullptr);
michael@0: 
michael@0:   nsCOMPtr<mozIStorageStatement> stmt;
michael@0:   nsresult rv = mConnection->CreateStatement(aQuery, getter_AddRefs(stmt));
michael@0:   if (NS_FAILED(rv)) {
michael@0:     nsCString error;
michael@0:     error.AppendLiteral("The statement '");
michael@0:     error.Append(aQuery);
michael@0:     error.AppendLiteral("' failed to compile with the error message '");
michael@0:     nsCString msg;
michael@0:     (void)mConnection->GetLastErrorString(msg);
michael@0:     error.Append(msg);
michael@0:     error.AppendLiteral("'.");
michael@0:     NS_ERROR(error.get());
michael@0:   }
michael@0:   NS_ENSURE_SUCCESS(rv, nullptr);
michael@0: 
michael@0:   return stmt.forget();
michael@0: }
michael@0: 
michael@0: template< >
michael@0: inline
michael@0: already_AddRefed<mozIStorageAsyncStatement>
michael@0: StatementCache<mozIStorageAsyncStatement>::CreateStatement(const nsACString& aQuery)
michael@0: {
michael@0:   NS_ENSURE_TRUE(mConnection, nullptr);
michael@0: 
michael@0:   nsCOMPtr<mozIStorageAsyncStatement> stmt;
michael@0:   nsresult rv = mConnection->CreateAsyncStatement(aQuery, getter_AddRefs(stmt));
michael@0:   NS_ENSURE_SUCCESS(rv, nullptr);
michael@0: 
michael@0:   return stmt.forget();
michael@0: }
michael@0: 
michael@0: } // namespace storage
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // mozilla_storage_StatementCache_h