libzmq/src/config.hpp

/*
    Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file

    This file is part of libzmq, the ZeroMQ core engine in C++.

    libzmq is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    As a special exception, the Contributors give you permission to link
    this library with independent modules to produce an executable,
    regardless of the license terms of these independent modules, and to
    copy and distribute the resulting executable under terms of your choice,
    provided that you also meet, for each linked independent module, the
    terms and conditions of the license of that module. An independent
    module is a module which is not derived from or based on this library.
    If you modify this library, you must extend this exception to your
    version of the library.

    libzmq 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 Lesser General Public
    License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __ZMQ_CONFIG_HPP_INCLUDED__
#define __ZMQ_CONFIG_HPP_INCLUDED__

namespace zmq
{

    //  Compile-time settings.

    enum
    {
        //  Number of new messages in message pipe needed to trigger new memory
        //  allocation. Setting this parameter to 256 decreases the impact of
        //  memory allocation by approximately 99.6%
        message_pipe_granularity = 256,

        //  Commands in pipe per allocation event.
        command_pipe_granularity = 16,

        //  Determines how often does socket poll for new commands when it
        //  still has unprocessed messages to handle. Thus, if it is set to 100,
        //  socket will process 100 inbound messages before doing the poll.
        //  If there are no unprocessed messages available, poll is done
        //  immediately. Decreasing the value trades overall latency for more
        //  real-time behaviour (less latency peaks).
        inbound_poll_rate = 100,

        //  Maximal batching size for engines with receiving functionality.
        //  So, if there are 10 messages that fit into the batch size, all of
        //  them may be read by a single 'recv' system call, thus avoiding
        //  unnecessary network stack traversals.
        in_batch_size = 8192,

        //  Maximal delta between high and low watermark.
        max_wm_delta = 1024,

        //  Maximum number of events the I/O thread can process in one go.
        max_io_events = 256,

        //  Maximal delay to process command in API thread (in CPU ticks).
        //  3,000,000 ticks equals to 1 - 2 milliseconds on current CPUs.
        //  Note that delay is only applied when there is continuous stream of
        //  messages to process. If not so, commands are processed immediately.
        max_command_delay = 3000000,

        //  Low-precision clock precision in CPU ticks. 1ms. Value of 1000000
        //  should be OK for CPU frequencies above 1GHz. If should work
        //  reasonably well for CPU frequencies above 500MHz. For lower CPU
        //  frequencies you may consider lowering this value to get best
        //  possible latencies.
        clock_precision = 1000000,

        //  On some OSes the signaler has to be emulated using a TCP
        //  connection. In such cases following port is used.
        //  If 0, it lets the OS choose a free port without requiring use of a 
        //  global mutex. The original implementation of a Windows signaler 
        //  socket used port 5905 instead of letting the OS choose a free port.
        //  https://github.com/zeromq/libzmq/issues/1542
        signaler_port = 0
    };

}

#endif