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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 <memory>
#include "mongo/base/disallow_copying.h"
#include "mongo/db/baton.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/rpc/message.h"
#include "mongo/transport/session_id.h"
#include "mongo/util/decorable.h"
#include "mongo/util/future.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace transport {
class TransportLayer;
class Session;
using SessionHandle = std::shared_ptr<Session>;
using ConstSessionHandle = std::shared_ptr<const Session>;
/**
* This type contains data needed to associate Messages with connections
* (on the transport side) and Messages with Client objects (on the database side).
*/
class Session : public std::enable_shared_from_this<Session>, public Decorable<Session> {
MONGO_DISALLOW_COPYING(Session);
public:
/**
* Type to indicate the internal id for this session.
*/
using Id = SessionId;
/**
* Tags for groups of connections.
*/
using TagMask = uint32_t;
static const Status ClosedStatus;
static constexpr TagMask kEmptyTagMask = 0;
static constexpr TagMask kKeepOpen = 1;
static constexpr TagMask kInternalClient = 2;
static constexpr TagMask kLatestVersionInternalClientKeepOpen = 4;
static constexpr TagMask kExternalClientKeepOpen = 8;
static constexpr TagMask kPending = 1 << 31;
virtual ~Session() = default;
Id id() const {
return _id;
}
virtual TransportLayer* getTransportLayer() const = 0;
/**
* Ends this Session.
*
* Operations on this Session that have already been started via wait() or asyncWait() will
* complete, but may return a failed Status. Future operations on this Session will fail. If
* this TransportLayer implementation is networked, any connections for this Session will be
* closed.
*
* This method is idempotent and synchronous.
*
* Destructors of derived classes will close the session automatically if needed. This method
* should only be called explicitly if the session should be closed separately from destruction,
* eg due to some outside event.
*/
virtual void end() = 0;
/**
* Source (receive) a new Message from the remote host for this Session.
*/
virtual StatusWith<Message> sourceMessage() = 0;
virtual Future<Message> asyncSourceMessage(const BatonHandle& handle = nullptr) = 0;
/**
* Sink (send) a Message to the remote host for this Session.
*
* Async version will keep the buffer alive until the operation completes.
*/
virtual Status sinkMessage(Message message) = 0;
virtual Future<void> asyncSinkMessage(Message message, const BatonHandle& handle = nullptr) = 0;
/**
* Cancel any outstanding async operations. There is no way to cancel synchronous calls.
* Futures will finish with an ErrorCodes::CallbackCancelled error if they haven't already
* completed.
*/
virtual void cancelAsyncOperations(const BatonHandle& handle = nullptr) = 0;
/**
* This should only be used to detect when the remote host has disappeared without
* notice. It does NOT work correctly for ensuring that operations complete or fail
* by some deadline.
*
* This timeout will only effect calls sourceMessage()/sinkMessage(). Async operations do not
* currently support timeouts.
*/
virtual void setTimeout(boost::optional<Milliseconds> timeout) = 0;
/**
* This will return whether calling sourceMessage()/sinkMessage() will fail with an EOF error.
*
* Implementations may actually perform some I/O or call syscalls to determine this, rather
* than just checking a flag.
*
* This must not be called while the session is currently sourcing or sinking a message.
*/
virtual bool isConnected() = 0;
virtual const HostAndPort& remote() const = 0;
virtual const HostAndPort& local() const = 0;
/**
* Atomically set all of the session tags specified in the 'tagsToSet' bit field. If the
* 'kPending' tag is set, indicating that no tags have yet been specified for the session, this
* function also clears that tag as part of the same atomic operation.
*
* The 'kPending' tag is only for new sessions; callers should not set it directly.
*/
void setTags(TagMask tagsToSet);
/**
* Atomically clears all of the session tags specified in the 'tagsToUnset' bit field. If the
* 'kPending' tag is set, indicating that no tags have yet been specified for the session, this
* function also clears that tag as part of the same atomic operation.
*/
void unsetTags(TagMask tagsToUnset);
/**
* Loads the session tags, passes them to 'mutateFunc' and then stores the result of that call
* as the new session tags, all in one atomic operation.
*
* In order to ensure atomicity, 'mutateFunc' may get called multiple times, so it should not
* perform expensive computations or operations with side effects.
*
* If the 'kPending' tag is set originally, mutateTags() will unset it regardless of the result
* of the 'mutateFunc' call. The 'kPending' tag is only for new sessions; callers should never
* try to set it.
*/
void mutateTags(const stdx::function<TagMask(TagMask)>& mutateFunc);
TagMask getTags() const;
protected:
Session();
private:
const Id _id;
AtomicWord<TagMask> _tags;
};
} // namespace transport
} // namespace mongo
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