1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/storage/public/StatementCache.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,148 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef mozilla_storage_StatementCache_h
1.11 +#define mozilla_storage_StatementCache_h
1.12 +
1.13 +#include "mozIStorageConnection.h"
1.14 +#include "mozIStorageStatement.h"
1.15 +#include "mozIStorageAsyncStatement.h"
1.16 +
1.17 +#include "nsAutoPtr.h"
1.18 +#include "nsHashKeys.h"
1.19 +#include "nsInterfaceHashtable.h"
1.20 +
1.21 +namespace mozilla {
1.22 +namespace storage {
1.23 +
1.24 +/**
1.25 + * Class used to cache statements (mozIStorageStatement or
1.26 + * mozIStorageAsyncStatement).
1.27 + */
1.28 +template<typename StatementType>
1.29 +class StatementCache {
1.30 +public:
1.31 + /**
1.32 + * Constructor for the cache.
1.33 + *
1.34 + * @note a connection can have more than one cache.
1.35 + *
1.36 + * @param aConnection
1.37 + * A reference to the nsCOMPtr for the connection this cache is to be
1.38 + * used for. This nsCOMPtr must at least live as long as this class,
1.39 + * otherwise crashes will happen.
1.40 + */
1.41 + StatementCache(nsCOMPtr<mozIStorageConnection>& aConnection)
1.42 + : mConnection(aConnection)
1.43 + {
1.44 + }
1.45 +
1.46 + /**
1.47 + * Obtains a cached statement. If this statement is not yet created, it will
1.48 + * be created and stored for later use.
1.49 + *
1.50 + * @param aQuery
1.51 + * The SQL string (either a const char [] or nsACString) to get a
1.52 + * cached query for.
1.53 + * @return the cached statement, or null upon error.
1.54 + */
1.55 + inline
1.56 + already_AddRefed<StatementType>
1.57 + GetCachedStatement(const nsACString& aQuery)
1.58 + {
1.59 + nsCOMPtr<StatementType> stmt;
1.60 + if (!mCachedStatements.Get(aQuery, getter_AddRefs(stmt))) {
1.61 + stmt = CreateStatement(aQuery);
1.62 + NS_ENSURE_TRUE(stmt, nullptr);
1.63 +
1.64 + mCachedStatements.Put(aQuery, stmt);
1.65 + }
1.66 + return stmt.forget();
1.67 + }
1.68 +
1.69 + template<int N>
1.70 + MOZ_ALWAYS_INLINE already_AddRefed<StatementType>
1.71 + GetCachedStatement(const char (&aQuery)[N])
1.72 + {
1.73 + nsDependentCString query(aQuery, N - 1);
1.74 + return GetCachedStatement(query);
1.75 + }
1.76 +
1.77 + /**
1.78 + * Finalizes all cached statements so the database can be safely closed. The
1.79 + * behavior of this cache is unspecified after this method is called.
1.80 + */
1.81 + inline
1.82 + void
1.83 + FinalizeStatements()
1.84 + {
1.85 + (void)mCachedStatements.Enumerate(FinalizeCachedStatements, nullptr);
1.86 +
1.87 + // Clear the cache at this time too!
1.88 + (void)mCachedStatements.Clear();
1.89 + }
1.90 +
1.91 +private:
1.92 + inline
1.93 + already_AddRefed<StatementType>
1.94 + CreateStatement(const nsACString& aQuery);
1.95 + static
1.96 + PLDHashOperator
1.97 + FinalizeCachedStatements(const nsACString& aKey,
1.98 + nsCOMPtr<StatementType>& aStatement,
1.99 + void*)
1.100 + {
1.101 + (void)aStatement->Finalize();
1.102 + return PL_DHASH_NEXT;
1.103 + }
1.104 +
1.105 + nsInterfaceHashtable<nsCStringHashKey, StatementType> mCachedStatements;
1.106 + nsCOMPtr<mozIStorageConnection>& mConnection;
1.107 +};
1.108 +
1.109 +template< >
1.110 +inline
1.111 +already_AddRefed<mozIStorageStatement>
1.112 +StatementCache<mozIStorageStatement>::CreateStatement(const nsACString& aQuery)
1.113 +{
1.114 + NS_ENSURE_TRUE(mConnection, nullptr);
1.115 +
1.116 + nsCOMPtr<mozIStorageStatement> stmt;
1.117 + nsresult rv = mConnection->CreateStatement(aQuery, getter_AddRefs(stmt));
1.118 + if (NS_FAILED(rv)) {
1.119 + nsCString error;
1.120 + error.AppendLiteral("The statement '");
1.121 + error.Append(aQuery);
1.122 + error.AppendLiteral("' failed to compile with the error message '");
1.123 + nsCString msg;
1.124 + (void)mConnection->GetLastErrorString(msg);
1.125 + error.Append(msg);
1.126 + error.AppendLiteral("'.");
1.127 + NS_ERROR(error.get());
1.128 + }
1.129 + NS_ENSURE_SUCCESS(rv, nullptr);
1.130 +
1.131 + return stmt.forget();
1.132 +}
1.133 +
1.134 +template< >
1.135 +inline
1.136 +already_AddRefed<mozIStorageAsyncStatement>
1.137 +StatementCache<mozIStorageAsyncStatement>::CreateStatement(const nsACString& aQuery)
1.138 +{
1.139 + NS_ENSURE_TRUE(mConnection, nullptr);
1.140 +
1.141 + nsCOMPtr<mozIStorageAsyncStatement> stmt;
1.142 + nsresult rv = mConnection->CreateAsyncStatement(aQuery, getter_AddRefs(stmt));
1.143 + NS_ENSURE_SUCCESS(rv, nullptr);
1.144 +
1.145 + return stmt.forget();
1.146 +}
1.147 +
1.148 +} // namespace storage
1.149 +} // namespace mozilla
1.150 +
1.151 +#endif // mozilla_storage_StatementCache_h
