1 /**

     2  * Relational pipes

     3  * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)

     4  *

     5  * This program is free software: you can redistribute it and/or modify

     6  * it under the terms of the GNU General Public License as published by

     7  * the Free Software Foundation, version 3 of the License.

     8  *

     9  * This program is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

    12  * GNU General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU General Public License

    15  * along with this program. If not, see <http://www.gnu.org/licenses/>.

    16  */

    17 #pragma once

    18 

    19 #include <mqueue.h>

    20 #include <string>

    21 #include <stdexcept>

    22 #include <cstring>

    23 

    24 namespace relpipe {

    25 namespace in {

    26 namespace posixmq {

    27 

    28 class PosixMQ {

    29 private:

    30 	size_t MSG_SIZE = 8192; // TODO: configurable/dynamic

    31 	std::string queueName;

    32 	mqd_t handle = -2;

    33 

    34 	PosixMQ(std::string queueName, mqd_t handle) : queueName(queueName), handle(handle) {

    35 	}

    36 

    37 public:

    38 

    39 	virtual ~PosixMQ() {

    40 		if (handle >= 0) mq_close(handle);

    41 	}

    42 

    43 	static PosixMQ* open(std::string queueName) {

    44 		mqd_t handle = mq_open(queueName.c_str(), O_RDONLY | O_CREAT);

    45 		if (handle >= 0) return new PosixMQ(queueName, handle);

    46 		else throw std::logic_error("Unable to open PosixMQ: " + queueName + " error: " + strerror(errno));

    47 	}

    48 

    49 	std::string receive() {

    50 		char buffer[MSG_SIZE + 1];

    51 		memset(buffer, 0, MSG_SIZE + 1);

    52 		ssize_t msgSize = mq_receive(handle, buffer, MSG_SIZE, nullptr);

    53 

    54 		if (msgSize >= 0) return std::string(buffer);

    55 		else throw std::logic_error("Unable to receive PosixMQ message from " + queueName + " error: " + strerror(errno));

    56 	}

    57 

    58 	void unlink() {

    59 		mq_unlink(queueName.c_str());

    60 	}

    61 

    62 };

    63 

    64 }

    65 }

    66 }