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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <memory>
#include "mongo/base/status.h"
#include "mongo/stdx/functional.h"
#include "mongo/transport/session.h"
#include "mongo/util/future.h"
#include "mongo/util/time_support.h"
namespace mongo {
class OperationContext;
namespace transport {
enum ConnectSSLMode { kGlobalSSLMode, kEnableSSL, kDisableSSL };
class Reactor;
using ReactorHandle = std::shared_ptr<Reactor>;
/**
* The TransportLayer moves Messages between transport::Endpoints and the database.
* This class owns an Acceptor that generates new endpoints from which it can
* source Messages.
*
* The TransportLayer creates Session objects and maps them internally to
* endpoints. New Sessions are passed to the database (via a ServiceEntryPoint)
* to be run. The database must then call additional methods on the TransportLayer
* to manage the Session in a get-Message, handle-Message, return-Message cycle.
* It must do this on its own thread(s).
*
* References to the TransportLayer should be stored on service context objects.
*/
class TransportLayer {
MONGO_DISALLOW_COPYING(TransportLayer);
public:
static const Status SessionUnknownStatus;
static const Status ShutdownStatus;
static const Status TicketSessionUnknownStatus;
static const Status TicketSessionClosedStatus;
friend class Session;
virtual ~TransportLayer() = default;
virtual StatusWith<SessionHandle> connect(HostAndPort peer,
ConnectSSLMode sslMode,
Milliseconds timeout) = 0;
virtual Future<SessionHandle> asyncConnect(HostAndPort peer,
ConnectSSLMode sslMode,
const ReactorHandle& reactor,
Milliseconds timeout) = 0;
/**
* Start the TransportLayer. After this point, the TransportLayer will begin accepting active
* sessions from new transport::Endpoints.
*/
virtual Status start() = 0;
/**
* Shut the TransportLayer down. After this point, the TransportLayer will
* end all active sessions and won't accept new transport::Endpoints. Any
* future calls to wait() or asyncWait() will fail. This method is synchronous and
* will not return until all sessions have ended and any network connections have been
* closed.
*/
virtual void shutdown() = 0;
/**
* Optional method for subclasses to setup their state before being ready to accept
* connections.
*/
virtual Status setup() = 0;
enum WhichReactor { kIngress, kEgress, kNewReactor };
virtual ReactorHandle getReactor(WhichReactor which) = 0;
virtual BatonHandle makeBaton(OperationContext* opCtx) {
return nullptr;
}
protected:
TransportLayer() = default;
};
class ReactorTimer {
public:
ReactorTimer() = default;
ReactorTimer(const ReactorTimer&) = delete;
ReactorTimer& operator=(const ReactorTimer&) = delete;
/*
* The destructor calls cancel() to ensure outstanding Futures are filled.
*/
virtual ~ReactorTimer() = default;
/*
* Cancel any outstanding future from waitFor/waitUntil. The future will be filled with an
* ErrorCodes::CallbackCancelled status.
*
* If no future is outstanding, then this is a noop.
*/
virtual void cancel(const BatonHandle& baton = nullptr) = 0;
/*
* Returns a future that will be filled with Status::OK after the deadline has passed.
*
* Calling this implicitly calls cancel().
*/
virtual Future<void> waitUntil(Date_t deadline, const BatonHandle& baton = nullptr) = 0;
};
class Reactor {
public:
Reactor(const Reactor&) = delete;
Reactor& operator=(const Reactor&) = delete;
virtual ~Reactor() = default;
/*
* Run the event loop of the reactor until stop() is called.
*/
virtual void run() noexcept = 0;
virtual void runFor(Milliseconds time) noexcept = 0;
virtual void stop() = 0;
virtual void drain() = 0;
using Task = stdx::function<void()>;
enum ScheduleMode { kDispatch, kPost };
virtual void schedule(ScheduleMode mode, Task task) = 0;
template <typename Callback>
Future<FutureContinuationResult<Callback>> execute(Callback&& cb) {
auto pf = makePromiseFuture<FutureContinuationResult<Callback>>();
schedule(kPost, [ cb = std::forward<Callback>(cb), sp = pf.promise.share() ]() mutable {
sp.setWith(cb);
});
return std::move(pf.future);
}
virtual bool onReactorThread() const = 0;
/*
* Makes a timer tied to this reactor's event loop. Timeout callbacks will be
* executed in a thread calling run() or runFor().
*/
virtual std::unique_ptr<ReactorTimer> makeTimer() = 0;
virtual Date_t now() = 0;
protected:
Reactor() = default;
};
} // namespace transport
} // namespace mongo
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