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