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