pipe.cpp

/* SPDX-License-Identifier: MPL-2.0 */

#include "precompiled.hpp"
#include <new>
#include <stddef.h>

#include "macros.hpp"
#include "pipe.hpp"
#include "err.hpp"

#include "ypipe.hpp"
#include "ypipe_conflate.hpp"

int zmq::pipepair (object_t *parents_[2],
                   pipe_t *pipes_[2],
                   const int hwms_[2],
                   const bool conflate_[2])
{
    //   Creates two pipe objects. These objects are connected by two ypipes,
    //   each to pass messages in one direction.

    typedef ypipe_t<msg_t, message_pipe_granularity> upipe_normal_t;
    typedef ypipe_conflate_t<msg_t> upipe_conflate_t;

    pipe_t::upipe_t *upipe1;
    if (conflate_[0])
        upipe1 = new (std::nothrow) upipe_conflate_t ();
    else
        upipe1 = new (std::nothrow) upipe_normal_t ();
    alloc_assert (upipe1);

    pipe_t::upipe_t *upipe2;
    if (conflate_[1])
        upipe2 = new (std::nothrow) upipe_conflate_t ();
    else
        upipe2 = new (std::nothrow) upipe_normal_t ();
    alloc_assert (upipe2);

    pipes_[0] = new (std::nothrow)
      pipe_t (parents_[0], upipe1, upipe2, hwms_[1], hwms_[0], conflate_[0]);
    alloc_assert (pipes_[0]);
    pipes_[1] = new (std::nothrow)
      pipe_t (parents_[1], upipe2, upipe1, hwms_[0], hwms_[1], conflate_[1]);
    alloc_assert (pipes_[1]);

    pipes_[0]->set_peer (pipes_[1]);
    pipes_[1]->set_peer (pipes_[0]);

    return 0;
}

void zmq::send_routing_id (pipe_t *pipe_, const options_t &options_)
{
    zmq::msg_t id;
    const int rc = id.init_size (options_.routing_id_size);
    errno_assert (rc == 0);
    memcpy (id.data (), options_.routing_id, options_.routing_id_size);
    id.set_flags (zmq::msg_t::routing_id);
    const bool written = pipe_->write (&id);
    zmq_assert (written);
    pipe_->flush ();
}

void zmq::send_hello_msg (pipe_t *pipe_, const options_t &options_)
{
    zmq::msg_t hello;
    const int rc =
      hello.init_buffer (&options_.hello_msg[0], options_.hello_msg.size ());
    errno_assert (rc == 0);
    const bool written = pipe_->write (&hello);
    zmq_assert (written);
    pipe_->flush ();
}

zmq::pipe_t::pipe_t (object_t *parent_,
                     upipe_t *inpipe_,
                     upipe_t *outpipe_,
                     int inhwm_,
                     int outhwm_,
                     bool conflate_) :
    object_t (parent_),
    _in_pipe (inpipe_),
    _out_pipe (outpipe_),
    _in_active (true),
    _out_active (true),
    _hwm (outhwm_),
    _lwm (compute_lwm (inhwm_)),
    _in_hwm_boost (-1),
    _out_hwm_boost (-1),
    _msgs_read (0),
    _msgs_written (0),
    _peers_msgs_read (0),
    _peer (NULL),
    _sink (NULL),
    _state (active),
    _delay (true),
    _server_socket_routing_id (0),
    _conflate (conflate_)
{
    _disconnect_msg.init ();
}

zmq::pipe_t::~pipe_t ()
{
    _disconnect_msg.close ();
}

void zmq::pipe_t::set_peer (pipe_t *peer_)
{
    //  Peer can be set once only.
    zmq_assert (!_peer);
    _peer = peer_;
}

void zmq::pipe_t::set_event_sink (i_pipe_events *sink_)
{
    // Sink can be set once only.
    zmq_assert (!_sink);
    _sink = sink_;
}

void zmq::pipe_t::set_server_socket_routing_id (
  uint32_t server_socket_routing_id_)
{
    _server_socket_routing_id = server_socket_routing_id_;
}

uint32_t zmq::pipe_t::get_server_socket_routing_id () const
{
    return _server_socket_routing_id;
}

void zmq::pipe_t::set_router_socket_routing_id (
  const blob_t &router_socket_routing_id_)
{
    _router_socket_routing_id.set_deep_copy (router_socket_routing_id_);
}

const zmq::blob_t &zmq::pipe_t::get_routing_id () const
{
    return _router_socket_routing_id;
}

bool zmq::pipe_t::check_read ()
{
    if (unlikely (!_in_active))
        return false;
    if (unlikely (_state != active && _state != waiting_for_delimiter))
        return false;

    //  Check if there's an item in the pipe.
    if (!_in_pipe->check_read ()) {
        _in_active = false;
        return false;
    }

    //  If the next item in the pipe is message delimiter,
    //  initiate termination process.
    if (_in_pipe->probe (is_delimiter)) {
        msg_t msg;
        const bool ok = _in_pipe->read (&msg);
        zmq_assert (ok);
        process_delimiter ();
        return false;
    }

    return true;
}

bool zmq::pipe_t::read (msg_t *msg_)
{
    if (unlikely (!_in_active))
        return false;
    if (unlikely (_state != active && _state != waiting_for_delimiter))
        return false;

    while (true) {
        if (!_in_pipe->read (msg_)) {
            _in_active = false;
            return false;
        }

        //  If this is a credential, ignore it and receive next message.
        if (unlikely (msg_->is_credential ())) {
            const int rc = msg_->close ();
            zmq_assert (rc == 0);
        } else {
            break;
        }
    }

    //  If delimiter was read, start termination process of the pipe.
    if (msg_->is_delimiter ()) {
        process_delimiter ();
        return false;
    }

    if (!(msg_->flags () & msg_t::more) && !msg_->is_routing_id ())
        _msgs_read++;

    if (_lwm > 0 && _msgs_read % _lwm == 0)
        send_activate_write (_peer, _msgs_read);

    return true;
}

bool zmq::pipe_t::check_write ()
{
    if (unlikely (!_out_active || _state != active))
        return false;

    const bool full = !check_hwm ();

    if (unlikely (full)) {
        _out_active = false;
        return false;
    }

    return true;
}

bool zmq::pipe_t::write (const msg_t *msg_)
{
    if (unlikely (!check_write ()))
        return false;

    const bool more = (msg_->flags () & msg_t::more) != 0;
    const bool is_routing_id = msg_->is_routing_id ();
    _out_pipe->write (*msg_, more);
    if (!more && !is_routing_id)
        _msgs_written++;

    return true;
}

void zmq::pipe_t::rollback () const
{
    //  Remove incomplete message from the outbound pipe.
    msg_t msg;
    if (_out_pipe) {
        while (_out_pipe->unwrite (&msg)) {
            zmq_assert (msg.flags () & msg_t::more);
            const int rc = msg.close ();
            errno_assert (rc == 0);
        }
    }
}

void zmq::pipe_t::flush ()
{
    //  The peer does not exist anymore at this point.
    if (_state == term_ack_sent)
        return;

    if (_out_pipe && !_out_pipe->flush ())
        send_activate_read (_peer);
}

void zmq::pipe_t::process_activate_read ()
{
    if (!_in_active && (_state == active || _state == waiting_for_delimiter)) {
        _in_active = true;
        _sink->read_activated (this);
    }
}

void zmq::pipe_t::process_activate_write (uint64_t msgs_read_)
{
    //  Remember the peer's message sequence number.
    _peers_msgs_read = msgs_read_;

    if (!_out_active && _state == active) {
        _out_active = true;
        _sink->write_activated (this);
    }
}

void zmq::pipe_t::process_hiccup (void *pipe_)
{
    //  Destroy old outpipe. Note that the read end of the pipe was already
    //  migrated to this thread.
    zmq_assert (_out_pipe);
    _out_pipe->flush ();
    msg_t msg;
    while (_out_pipe->read (&msg)) {
        if (!(msg.flags () & msg_t::more))
            _msgs_written--;
        const int rc = msg.close ();
        errno_assert (rc == 0);
    }
    LIBZMQ_DELETE (_out_pipe);

    //  Plug in the new outpipe.
    zmq_assert (pipe_);
    _out_pipe = static_cast<upipe_t *> (pipe_);
    _out_active = true;

    //  If appropriate, notify the user about the hiccup.
    if (_state == active)
        _sink->hiccuped (this);
}

void zmq::pipe_t::process_pipe_term ()
{
    zmq_assert (_state == active || _state == delimiter_received
                || _state == term_req_sent1);

    //  This is the simple case of peer-induced termination. If there are no
    //  more pending messages to read, or if the pipe was configured to drop
    //  pending messages, we can move directly to the term_ack_sent state.
    //  Otherwise we'll hang up in waiting_for_delimiter state till all
    //  pending messages are read.
    if (_state == active) {
        if (_delay)
            _state = waiting_for_delimiter;
        else {
            _state = term_ack_sent;
            _out_pipe = NULL;
            send_pipe_term_ack (_peer);
        }
    }

    //  Delimiter happened to arrive before the term command. Now we have the
    //  term command as well, so we can move straight to term_ack_sent state.
    else if (_state == delimiter_received) {
        _state = term_ack_sent;
        _out_pipe = NULL;
        send_pipe_term_ack (_peer);
    }

    //  This is the case where both ends of the pipe are closed in parallel.
    //  We simply reply to the request by ack and continue waiting for our
    //  own ack.
    else if (_state == term_req_sent1) {
        _state = term_req_sent2;
        _out_pipe = NULL;
        send_pipe_term_ack (_peer);
    }
}

void zmq::pipe_t::process_pipe_term_ack ()
{
    //  Notify the user that all the references to the pipe should be dropped.
    zmq_assert (_sink);
    _sink->pipe_terminated (this);

    //  In term_ack_sent and term_req_sent2 states there's nothing to do.
    //  Simply deallocate the pipe. In term_req_sent1 state we have to ack
    //  the peer before deallocating this side of the pipe.
    //  All the other states are invalid.
    if (_state == term_req_sent1) {
        _out_pipe = NULL;
        send_pipe_term_ack (_peer);
    } else
        zmq_assert (_state == term_ack_sent || _state == term_req_sent2);

    //  We'll deallocate the inbound pipe, the peer will deallocate the outbound
    //  pipe (which is an inbound pipe from its point of view).
    //  First, delete all the unread messages in the pipe. We have to do it by
    //  hand because msg_t doesn't have automatic destructor. Then deallocate
    //  the ypipe itself.

    if (!_conflate) {
        msg_t msg;
        while (_in_pipe->read (&msg)) {
            const int rc = msg.close ();
            errno_assert (rc == 0);
        }
    }

    LIBZMQ_DELETE (_in_pipe);

    //  Deallocate the pipe object
    delete this;
}

void zmq::pipe_t::process_pipe_hwm (int inhwm_, int outhwm_)
{
    set_hwms (inhwm_, outhwm_);
}

void zmq::pipe_t::set_nodelay ()
{
    this->_delay = false;
}

void zmq::pipe_t::terminate (bool delay_)
{
    //  Overload the value specified at pipe creation.
    _delay = delay_;

    //  If terminate was already called, we can ignore the duplicate invocation.
    if (_state == term_req_sent1 || _state == term_req_sent2) {
        return;
    }
    //  If the pipe is in the final phase of async termination, it's going to
    //  closed anyway. No need to do anything special here.
    if (_state == term_ack_sent) {
        return;
    }
    //  The simple sync termination case. Ask the peer to terminate and wait
    //  for the ack.
    if (_state == active) {
        send_pipe_term (_peer);
        _state = term_req_sent1;
    }
    //  There are still pending messages available, but the user calls
    //  'terminate'. We can act as if all the pending messages were read.
    else if (_state == waiting_for_delimiter && !_delay) {
        //  Drop any unfinished outbound messages.
        rollback ();
        _out_pipe = NULL;
        send_pipe_term_ack (_peer);
        _state = term_ack_sent;
    }
    //  If there are pending messages still available, do nothing.
    else if (_state == waiting_for_delimiter) {
    }
    //  We've already got delimiter, but not term command yet. We can ignore
    //  the delimiter and ack synchronously terminate as if we were in
    //  active state.
    else if (_state == delimiter_received) {
        send_pipe_term (_peer);
        _state = term_req_sent1;
    }
    //  There are no other states.
    else {
        zmq_assert (false);
    }

    //  Stop outbound flow of messages.
    _out_active = false;

    if (_out_pipe) {
        //  Drop any unfinished outbound messages.
        rollback ();

        //  Write the delimiter into the pipe. Note that watermarks are not
        //  checked; thus the delimiter can be written even when the pipe is full.
        msg_t msg;
        msg.init_delimiter ();
        _out_pipe->write (msg, false);
        flush ();
    }
}

bool zmq::pipe_t::is_delimiter (const msg_t &msg_)
{
    return msg_.is_delimiter ();
}

int zmq::pipe_t::compute_lwm (int hwm_)
{
    //  Compute the low water mark. Following point should be taken
    //  into consideration:
    //
    //  1. LWM has to be less than HWM.
    //  2. LWM cannot be set to very low value (such as zero) as after filling
    //     the queue it would start to refill only after all the messages are
    //     read from it and thus unnecessarily hold the progress back.
    //  3. LWM cannot be set to very high value (such as HWM-1) as it would
    //     result in lock-step filling of the queue - if a single message is
    //     read from a full queue, writer thread is resumed to write exactly one
    //     message to the queue and go back to sleep immediately. This would
    //     result in low performance.
    //
    //  Given the 3. it would be good to keep HWM and LWM as far apart as
    //  possible to reduce the thread switching overhead to almost zero.
    //  Let's make LWM 1/2 of HWM.
    const int result = (hwm_ + 1) / 2;

    return result;
}

void zmq::pipe_t::process_delimiter ()
{
    zmq_assert (_state == active || _state == waiting_for_delimiter);

    if (_state == active)
        _state = delimiter_received;
    else {
        rollback ();
        _out_pipe = NULL;
        send_pipe_term_ack (_peer);
        _state = term_ack_sent;
    }
}

void zmq::pipe_t::hiccup ()
{
    //  If termination is already under way do nothing.
    if (_state != active)
        return;

    //  We'll drop the pointer to the inpipe. From now on, the peer is
    //  responsible for deallocating it.

    //  Create new inpipe.
    _in_pipe =
      _conflate
        ? static_cast<upipe_t *> (new (std::nothrow) ypipe_conflate_t<msg_t> ())
        : new (std::nothrow) ypipe_t<msg_t, message_pipe_granularity> ();

    alloc_assert (_in_pipe);
    _in_active = true;

    //  Notify the peer about the hiccup.
    send_hiccup (_peer, _in_pipe);
}

void zmq::pipe_t::set_hwms (int inhwm_, int outhwm_)
{
    int in = inhwm_ + std::max (_in_hwm_boost, 0);
    int out = outhwm_ + std::max (_out_hwm_boost, 0);

    // if either send or recv side has hwm <= 0 it means infinite so we should set hwms infinite
    if (inhwm_ <= 0 || _in_hwm_boost == 0)
        in = 0;

    if (outhwm_ <= 0 || _out_hwm_boost == 0)
        out = 0;

    _lwm = compute_lwm (in);
    _hwm = out;
}

void zmq::pipe_t::set_hwms_boost (int inhwmboost_, int outhwmboost_)
{
    _in_hwm_boost = inhwmboost_;
    _out_hwm_boost = outhwmboost_;
}

bool zmq::pipe_t::check_hwm () const
{
    const bool full =
      _hwm > 0 && _msgs_written - _peers_msgs_read >= uint64_t (_hwm);
    return !full;
}

void zmq::pipe_t::send_hwms_to_peer (int inhwm_, int outhwm_)
{
    if (_state == active)
        send_pipe_hwm (_peer, inhwm_, outhwm_);
}

void zmq::pipe_t::set_endpoint_pair (zmq::endpoint_uri_pair_t endpoint_pair_)
{
    _endpoint_pair = ZMQ_MOVE (endpoint_pair_);
}

const zmq::endpoint_uri_pair_t &zmq::pipe_t::get_endpoint_pair () const
{
    return _endpoint_pair;
}

void zmq::pipe_t::send_stats_to_peer (own_t *socket_base_)
{
    if (_state == active) {
        endpoint_uri_pair_t *ep =
          new (std::nothrow) endpoint_uri_pair_t (_endpoint_pair);
        send_pipe_peer_stats (_peer, _msgs_written - _peers_msgs_read,
                              socket_base_, ep);
    }
}

void zmq::pipe_t::process_pipe_peer_stats (uint64_t queue_count_,
                                           own_t *socket_base_,
                                           endpoint_uri_pair_t *endpoint_pair_)
{
    send_pipe_stats_publish (socket_base_, queue_count_,
                             _msgs_written - _peers_msgs_read, endpoint_pair_);
}

void zmq::pipe_t::send_disconnect_msg ()
{
    if (_disconnect_msg.size () > 0 && _out_pipe) {
        // Rollback any incomplete message in the pipe, and push the disconnect message.
        rollback ();

        _out_pipe->write (_disconnect_msg, false);
        flush ();
        _disconnect_msg.init ();
    }
}

void zmq::pipe_t::set_disconnect_msg (
  const std::vector<unsigned char> &disconnect_)
{
    _disconnect_msg.close ();
    const int rc =
      _disconnect_msg.init_buffer (&disconnect_[0], disconnect_.size ());
    errno_assert (rc == 0);
}

void zmq::pipe_t::send_hiccup_msg (const std::vector<unsigned char> &hiccup_)
{
    if (!hiccup_.empty () && _out_pipe) {
        msg_t msg;
        const int rc = msg.init_buffer (&hiccup_[0], hiccup_.size ());
        errno_assert (rc == 0);

        _out_pipe->write (msg, false);
        flush ();
    }
}