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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 <boost/optional.hpp>
#include "mongo/base/status.h"
#include "mongo/db/client.h"
#include "mongo/db/logical_session_cache_gen.h"
#include "mongo/db/logical_session_cache_stats_gen.h"
#include "mongo/db/logical_session_id_helpers.h"
#include "mongo/db/operation_context.h"
namespace mongo {
/**
* The interface for the logical session cache
*/
class LogicalSessionCache {
public:
/**
* Decorate the ServiceContext with a LogicalSessionCache instance.
*/
static LogicalSessionCache* get(ServiceContext* service);
static LogicalSessionCache* get(OperationContext* opCtx);
static void set(ServiceContext* service, std::unique_ptr<LogicalSessionCache> sessionCache);
virtual ~LogicalSessionCache() = 0;
/**
* Invoked on service shutdown time in order to join the cache's refresher and reaper tasks.
*/
virtual void joinOnShutDown() = 0;
/**
* Inserts a new authoritative session record into the cache.
*
* This method will insert the authoritative record into the sessions collection and should only
* be used when starting new sessions. It should not be used to insert records for existing
* sessions.
*/
virtual Status startSession(OperationContext* opCtx, const LogicalSessionRecord& record) = 0;
/**
* Vivifies the session in the cache. I.e. creates it if it isn't there, updates last use if it
* is.
*/
virtual Status vivify(OperationContext* opCtx, const LogicalSessionId& lsid) = 0;
/**
* enqueues LogicalSessionIds for removal during the next _refresh()
*/
virtual void endSessions(const LogicalSessionIdSet& lsids) = 0;
/**
* Refreshes the cache synchronously. This flushes all pending refreshes and inserts to the
* sessions collection.
*/
virtual Status refreshNow(OperationContext* opCtx) = 0;
/**
* Reaps transaction records synchronously.
*/
virtual void reapNow(OperationContext* opCtx) = 0;
/**
* Returns the number of session records currently in the cache.
*/
virtual size_t size() = 0;
/**
* Ennumerate all LogicalSessionId keys currently in the cache.
*/
virtual std::vector<LogicalSessionId> listIds() const = 0;
/**
* Ennumerate all LogicalSessionId keys in the cache for the given UserDigests.
*/
virtual std::vector<LogicalSessionId> listIds(
const std::vector<SHA256Block>& userDigest) const = 0;
/**
* Retrieve a LogicalSessionRecord by LogicalSessionId, if it exists in the cache.
*/
virtual boost::optional<LogicalSessionRecord> peekCached(const LogicalSessionId& id) const = 0;
/**
* Returns stats about the logical session cache and its recent operations.
*/
virtual LogicalSessionCacheStats getStats() = 0;
};
/**
* WARNING: This class should only be used for rare operations because it generates a new logical
* session ID that isn't reaped until the next refresh, which could overwhelm memory if called in a
* loop.
*/
class AlternativeSessionRegion {
public:
AlternativeSessionRegion(OperationContext* opCtx)
: _alternateClient(opCtx->getServiceContext()->makeClient("alternative-session-region")),
_acr(_alternateClient),
_newOpCtx(cc().makeOperationContext()),
_lsid(makeLogicalSessionId(opCtx)) {
_newOpCtx->setLogicalSessionId(_lsid);
}
~AlternativeSessionRegion() {
LogicalSessionCache::get(opCtx())->endSessions({_lsid});
}
OperationContext* opCtx() {
return &*_newOpCtx;
}
private:
ServiceContext::UniqueClient _alternateClient;
AlternativeClientRegion _acr;
ServiceContext::UniqueOperationContext _newOpCtx;
LogicalSessionId _lsid;
};
} // namespace mongo
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