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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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
#include "mongo/platform/basic.h"
#include <queue>
#include <sqlite3.h>
#include <string>
#include <vector>
#include "mongo/db/client.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/storage/mobile/mobile_session.h"
#include "mongo/db/storage/mobile/mobile_session_pool.h"
#include "mongo/db/storage/mobile/mobile_sqlite_statement.h"
#include "mongo/db/storage/mobile/mobile_util.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/log.h"
namespace mongo {
MobileDelayedOpQueue::MobileDelayedOpQueue() : _isEmpty(true) {}
void MobileDelayedOpQueue::enqueueOp(std::string& opQuery) {
_queueMutex.lock();
// If the queue is empty till now, update the cached atomic to reflect the new state.
if (_opQueryQueue.empty())
_isEmpty.store(false);
_opQueryQueue.push(opQuery);
LOG(MOBILE_LOG_LEVEL_LOW) << "MobileSE: Enqueued operation for delayed execution: " << opQuery;
_queueMutex.unlock();
}
void MobileDelayedOpQueue::execAndDequeueOp(MobileSession* session) {
std::string opQuery;
_queueMutex.lock();
if (!_opQueryQueue.empty()) {
opQuery = _opQueryQueue.front();
_opQueryQueue.pop();
// If the queue is empty now, set the cached atomic to reflect the new state.
if (_opQueryQueue.empty())
_isEmpty.store(true);
}
_queueMutex.unlock();
LOG(MOBILE_LOG_LEVEL_LOW) << "MobileSE: Retrying previously enqueued operation: " << opQuery;
try {
SqliteStatement::execQuery(session, opQuery);
} catch (const WriteConflictException&) {
// It is possible that this operation fails because of a transaction running in parallel.
// We re-enqueue it for now and keep retrying later.
LOG(MOBILE_LOG_LEVEL_LOW) << "MobileSE: Caught WriteConflictException while executing "
" previously enqueued operation, re-enquing it";
enqueueOp(opQuery);
}
}
void MobileDelayedOpQueue::execAndDequeueAllOps(MobileSession* session) {
// Keep trying till the queue empties
while (!_isEmpty.load())
execAndDequeueOp(session);
}
bool MobileDelayedOpQueue::isEmpty() {
return (_isEmpty.load());
}
MobileSessionPool::MobileSessionPool(const std::string& path,
const embedded::MobileOptions& options,
std::uint64_t maxPoolSize)
: _path(path), _options(options), _maxPoolSize(maxPoolSize) {}
MobileSessionPool::~MobileSessionPool() {
shutDown();
}
std::unique_ptr<MobileSession> MobileSessionPool::getSession(OperationContext* opCtx) {
stdx::unique_lock<stdx::mutex> lk(_mutex);
// We should never be able to get here after _shuttingDown is set, because no new operations
// should be allowed to start.
invariant(!_shuttingDown);
// Checks if there is an open session available.
if (!_sessions.empty()) {
sqlite3* session = _popSession_inlock();
return std::make_unique<MobileSession>(session, this);
}
// Checks if a new session can be opened.
if (_curPoolSize < _maxPoolSize) {
sqlite3* session;
int status = sqlite3_open(_path.c_str(), &session);
embedded::checkStatus(status, SQLITE_OK, "sqlite3_open");
embedded::configureSession(session, _options);
_curPoolSize++;
return std::make_unique<MobileSession>(session, this);
}
// There are no open sessions available and the maxPoolSize has been reached.
// waitForConditionOrInterrupt is notified when an open session is released and available.
opCtx->waitForConditionOrInterrupt(
_releasedSessionNotifier, lk, [&] { return !_sessions.empty(); });
sqlite3* session = _popSession_inlock();
return std::make_unique<MobileSession>(session, this);
}
void MobileSessionPool::releaseSession(MobileSession* session) {
// Retry drop that have been queued on failure
if (!failedDropsQueue.isEmpty())
failedDropsQueue.execAndDequeueOp(session);
stdx::lock_guard<stdx::mutex> lk(_mutex);
_sessions.push_back(session->getSession());
_releasedSessionNotifier.notify_one();
}
void MobileSessionPool::shutDown() {
stdx::unique_lock<stdx::mutex> lk(_mutex);
_shuttingDown = true;
// Retrieve the operation context from the thread's client if the client exists.
if (haveClient()) {
OperationContext* opCtx = cc().getOperationContext();
// Locks if the operation context still exists.
if (opCtx) {
opCtx->waitForConditionOrInterrupt(
_releasedSessionNotifier, lk, [&] { return _sessions.size() == _curPoolSize; });
}
} else {
_releasedSessionNotifier.wait(lk, [&] { return _sessions.size() == _curPoolSize; });
}
// Retry all the drops that have been queued on failure.
// Create a new sqlite session to do so, all other sessions might have been closed already.
if (!failedDropsQueue.isEmpty()) {
sqlite3* session;
int status = sqlite3_open(_path.c_str(), &session);
embedded::checkStatus(status, SQLITE_OK, "sqlite3_open");
std::unique_ptr<MobileSession> mobSession = std::make_unique<MobileSession>(session, this);
LOG(MOBILE_LOG_LEVEL_LOW) << "MobileSE: Executing queued drops at shutdown";
failedDropsQueue.execAndDequeueAllOps(mobSession.get());
sqlite3_close(session);
}
for (auto&& session : _sessions) {
sqlite3_close(session);
}
}
// This method should only be called when _sessions is locked.
sqlite3* MobileSessionPool::_popSession_inlock() {
sqlite3* session = _sessions.back();
_sessions.pop_back();
return session;
}
} // namespace mongo
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