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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <queue>
#include <sqlite3.h>
#include <string>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/storage/mobile/mobile_session.h"
#include "mongo/stdx/mutex.h"
namespace mongo {
class MobileSession;
/**
* This class manages a queue of operations delayed for some reason
*/
class MobileDelayedOpQueue final {
MONGO_DISALLOW_COPYING(MobileDelayedOpQueue);
public:
MobileDelayedOpQueue();
void enqueueOp(std::string& opQuery);
void execAndDequeueOp(MobileSession* session);
void execAndDequeueAllOps(MobileSession* session);
bool isEmpty();
private:
AtomicBool _isEmpty;
stdx::mutex _queueMutex;
std::queue<std::string> _opQueryQueue;
};
/**
* This class manages a pool of open sqlite3* objects.
*/
class MobileSessionPool final {
MONGO_DISALLOW_COPYING(MobileSessionPool);
public:
MobileSessionPool(const std::string& path, std::uint64_t maxPoolSize = 80);
~MobileSessionPool();
/**
* Returns a smart pointer to a previously released session for reuse, or creates a new session.
*/
std::unique_ptr<MobileSession> getSession(OperationContext* opCtx);
/**
* Returns a session to the pool for later reuse.
*/
void releaseSession(MobileSession* session);
/**
* Transitions the pool to shutting down mode. It waits until all sessions are released back
* into the pool and closes all open sessions.
*/
void shutDown();
// Failed drops get queued here and get re-tried periodically
MobileDelayedOpQueue failedDropsQueue;
private:
/**
* Gets the front element from _sessions and then pops it off the queue.
*/
sqlite3* _popSession_inlock();
// This is used to lock the _sessions vector.
stdx::mutex _mutex;
stdx::condition_variable _releasedSessionNotifier;
std::string _path;
/**
* PoolSize is the number of open sessions associated with the session pool.
*/
std::uint64_t _maxPoolSize = 80;
std::uint64_t _curPoolSize = 0;
bool _shuttingDown = false;
using SessionPool = std::vector<sqlite3*>;
SessionPool _sessions;
};
} // namespace mongo
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