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/**
* Copyright (C) 2014-2015 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 <boost/optional.hpp>
#include <string>
#include "mongo/base/disallow_copying.h"
#include "mongo/executor/task_executor.h"
#include "mongo/stdx/functional.h"
#include "mongo/transport/baton.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/future.h"
namespace mongo {
class BSONObjBuilder;
namespace executor {
MONGO_FAIL_POINT_DECLARE(networkInterfaceDiscardCommandsBeforeAcquireConn);
MONGO_FAIL_POINT_DECLARE(networkInterfaceDiscardCommandsAfterAcquireConn);
/**
* Interface to networking for use by TaskExecutor implementations.
*/
class NetworkInterface {
MONGO_DISALLOW_COPYING(NetworkInterface);
public:
using Response = RemoteCommandResponse;
using RemoteCommandCompletionFn = stdx::function<void(const TaskExecutor::ResponseStatus&)>;
virtual ~NetworkInterface();
/**
* Returns diagnostic info.
*/
virtual std::string getDiagnosticString() = 0;
/**
* Appends information about the connections on this NetworkInterface.
*/
virtual void appendConnectionStats(ConnectionPoolStats* stats) const = 0;
/**
* Starts up the network interface.
*
* It is valid to call all methods except shutdown() before this method completes. That is,
* implementations may not assume that startup() completes before startCommand() first
* executes.
*
* Called by the owning TaskExecutor inside its run() method.
*/
virtual void startup() = 0;
/**
* Shuts down the network interface. Must be called before this instance gets deleted,
* if startup() is called.
*
* Called by the owning TaskExecutor inside its run() method.
*/
virtual void shutdown() = 0;
/**
* Returns true if shutdown has been called, false otherwise.
*/
virtual bool inShutdown() const = 0;
/**
* Blocks the current thread (presumably the executor thread) until the network interface
* knows of work for the executor to perform.
*/
virtual void waitForWork() = 0;
/**
* Similar to waitForWork, but only blocks until "when".
*/
virtual void waitForWorkUntil(Date_t when) = 0;
/**
* Signals to the network interface that there is new work (such as a signaled event) for
* the executor to process. Wakes the executor from waitForWork() and friends.
*/
virtual void signalWorkAvailable() = 0;
/**
* Returns the current time.
*/
virtual Date_t now() = 0;
/**
* Returns the hostname of the current process.
*/
virtual std::string getHostName() = 0;
struct Counters {
uint64_t canceled = 0;
uint64_t timedOut = 0;
uint64_t failed = 0;
uint64_t succeeded = 0;
};
/*
* Returns a copy of the operation counters (see struct Counters above). This method should
* only be used in tests, and will invariant if getTestCommands() returns false.
*/
virtual Counters getCounters() const = 0;
/**
* Starts asynchronous execution of the command described by "request".
*
* The request mutated to append request metadata to be merged into the request messages.
*
* Returns ErrorCodes::ShutdownInProgress if NetworkInterface::shutdown has already started
* and Status::OK() otherwise. If it returns Status::OK(), then the onFinish argument will be
* executed by NetworkInterface eventually; otherwise, it will not.
*/
virtual Status startCommand(const TaskExecutor::CallbackHandle& cbHandle,
RemoteCommandRequest& request,
const RemoteCommandCompletionFn& onFinish,
const transport::BatonHandle& baton = nullptr) = 0;
Future<TaskExecutor::ResponseStatus> startCommand(
const TaskExecutor::CallbackHandle& cbHandle,
RemoteCommandRequest& request,
const transport::BatonHandle& baton = nullptr) {
auto pf = makePromiseFuture<TaskExecutor::ResponseStatus>();
auto status =
startCommand(cbHandle,
request,
[sp = pf.promise.share()](const TaskExecutor::ResponseStatus& rs) mutable {
sp.emplaceValue(rs);
},
baton);
return std::move(pf.future);
}
/**
* Requests cancelation of the network activity associated with "cbHandle" if it has not yet
* completed.
*/
virtual void cancelCommand(const TaskExecutor::CallbackHandle& cbHandle,
const transport::BatonHandle& baton = nullptr) = 0;
/**
* Sets an alarm, which schedules "action" to run no sooner than "when".
*
* Returns ErrorCodes::ShutdownInProgress if NetworkInterface::shutdown has already started
* and true otherwise. If it returns Status::OK(), then the action will be executed by
* NetworkInterface eventually if no error occurs while waiting for the alarm; otherwise,
* it will not.
*
* "action" should not do anything that requires a lot of computation, or that might block for a
* long time, as it may execute in a network thread.
*
* Any callbacks invoked from setAlarm must observe onNetworkThread to
* return true. See that method for why.
*/
virtual Status setAlarm(Date_t when,
const stdx::function<void()>& action,
const transport::BatonHandle& baton = nullptr) = 0;
/**
* Returns true if called from a thread dedicated to networking. I.e. not a
* calling thread.
*
* This is meant to be used to avoid context switches, so callers must be
* able to rely on this returning true in a callback or completion handler.
* In the absence of any actual networking thread, always return true.
*/
virtual bool onNetworkThread() = 0;
/**
* Drops all connections to the given host in the connection pool.
*/
virtual void dropConnections(const HostAndPort& hostAndPort) = 0;
protected:
NetworkInterface();
};
} // namespace executor
} // namespace mongo
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