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/**
* Copyright (C) 2023-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 <string>
#include "mongo/util/interruptible.h"
#include "mongo/util/producer_consumer_queue.h"
#include "mongo/util/shared_buffer.h"
#include "mongo/util/time_support.h"
namespace mongo::transport::grpc {
/**
* A bidirectional channel with two ends. Each end constitutes a single producer and a single
* consumer.
*
* The "left" and "right" ends of the pipe have identical capabilities.
*/
class BidirectionalPipe {
public:
class End {
public:
/**
* Attempts to write a message to the pipe, returning true on success.
* If the pipe is closed before or during the write, this method returns false.
* If the write is interrupted by the provided Interruptible, this method will throw an
* exception.
*/
bool write(ConstSharedBuffer msg,
Interruptible* interruptible = Interruptible::notInterruptible()) {
try {
auto toWrite = SharedBuffer::allocate(msg.capacity());
memcpy(toWrite.get(), msg.get(), msg.capacity());
_sendHalf.push(std::move(toWrite), interruptible);
return true;
} catch (DBException& e) {
if (_isPipeClosedError(e)) {
return false;
}
throw;
}
}
/**
* Attempts to read a message to the pipe.
* If the pipe is closed before or during the read, this method returns
* boost::optional::none(). If the read is interrupted by the provided Interruptible, this
* method will throw an exception.
*/
boost::optional<SharedBuffer> read(
Interruptible* interruptible = Interruptible::notInterruptible()) {
try {
return _recvHalf.pop(interruptible);
} catch (DBException& e) {
if (_isPipeClosedError(e)) {
return boost::none;
}
throw;
}
}
/**
* Close both the read and write halves of this end of the pipe. In-progress reads and
* writes on this end and writes on the other end will be interrupted.
*
* Messages that have already been transmitted through this end of the pipe can still be
* read by the other end.
*/
void close() {
_sendHalf.close();
_recvHalf.close();
}
/**
* Returns true when at least one of the following conditions is met:
* - This end of the pipe is closed.
* - The other end of the pipe is closed and there are no more messages to be read.
*/
bool isConsumed() const {
auto stats = _recvHalfCtrl.getStats();
return stats.consumerEndClosed || (stats.queueDepth == 0 && stats.producerEndClosed);
}
private:
friend BidirectionalPipe;
explicit End(SingleProducerSingleConsumerQueue<SharedBuffer>::Producer send,
SingleProducerSingleConsumerQueue<SharedBuffer>::Consumer recv,
SingleProducerSingleConsumerQueue<SharedBuffer>::Controller recvCtrl)
: _sendHalf{std::move(send)},
_recvHalf{std::move(recv)},
_recvHalfCtrl(std::move(recvCtrl)) {}
bool _isPipeClosedError(const DBException& e) const {
return e.code() == ErrorCodes::ProducerConsumerQueueEndClosed ||
e.code() == ErrorCodes::ProducerConsumerQueueConsumed;
}
SingleProducerSingleConsumerQueue<SharedBuffer>::Producer _sendHalf;
SingleProducerSingleConsumerQueue<SharedBuffer>::Consumer _recvHalf;
SingleProducerSingleConsumerQueue<SharedBuffer>::Controller _recvHalfCtrl;
};
BidirectionalPipe() {
SingleProducerSingleConsumerQueue<SharedBuffer>::Pipe pipe1;
SingleProducerSingleConsumerQueue<SharedBuffer>::Pipe pipe2;
left = std::unique_ptr<End>(new End(
std::move(pipe1.producer), std::move(pipe2.consumer), std::move(pipe2.controller)));
right = std::unique_ptr<End>(new End(
std::move(pipe2.producer), std::move(pipe1.consumer), std::move(pipe1.controller)));
}
std::unique_ptr<End> left;
std::unique_ptr<End> right;
};
} // namespace mongo::transport::grpc
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