libzmq/src/socket_base.cpp

/*
    Copyright (c) 2007-2010 iMatix Corporation

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the Lesser GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ 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
    Lesser GNU General Public License for more details.

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

#include <new>
#include <string>
#include <algorithm>

#include "../include/zmq.h"

#include "platform.hpp"

#if defined ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#if defined _MSC_VER
#include <intrin.h>
#endif
#else
#include <unistd.h>
#endif

#include "socket_base.hpp"
#include "zmq_listener.hpp"
#include "zmq_connecter.hpp"
#include "io_thread.hpp"
#include "connect_session.hpp"
#include "config.hpp"
#include "pipe.hpp"
#include "err.hpp"
#include "ctx.hpp"
#include "platform.hpp"
#include "likely.hpp"
#include "pair.hpp"
#include "pub.hpp"
#include "sub.hpp"
#include "req.hpp"
#include "rep.hpp"
#include "pull.hpp"
#include "push.hpp"
#include "xreq.hpp"
#include "xrep.hpp"
#include "uuid.hpp"

//  If the RDTSC is available we use it to prevent excessive
//  polling for commands. The nice thing here is that it will work on any
//  system with x86 architecture and gcc or MSVC compiler.
#if (defined __GNUC__ && (defined __i386__ || defined __x86_64__)) ||\
    (defined _MSC_VER && (defined _M_IX86 || defined _M_X64))
#define ZMQ_DELAY_COMMANDS
#endif

zmq::socket_base_t *zmq::socket_base_t::create (int type_, class ctx_t *parent_,
    uint32_t slot_)
{
    socket_base_t *s = NULL;
    switch (type_) {

    case ZMQ_PAIR:
        s = new (std::nothrow) pair_t (parent_, slot_);
        break;
    case ZMQ_PUB:
        s = new (std::nothrow) pub_t (parent_, slot_);
        break;
    case ZMQ_SUB:
        s = new (std::nothrow) sub_t (parent_, slot_);
        break;
    case ZMQ_REQ:
        s = new (std::nothrow) req_t (parent_, slot_);
        break;
    case ZMQ_REP:
        s = new (std::nothrow) rep_t (parent_, slot_);
        break;
    case ZMQ_XREQ:
        s = new (std::nothrow) xreq_t (parent_, slot_);
        break;
    case ZMQ_XREP:
        s = new (std::nothrow) xrep_t (parent_, slot_);
        break;     
    case ZMQ_PULL:
        s = new (std::nothrow) pull_t (parent_, slot_);
        break;
    case ZMQ_PUSH:
        s = new (std::nothrow) push_t (parent_, slot_);
        break;
    default:
        errno = EINVAL;
        return NULL;
    }
    zmq_assert (s);
    return s;
}

zmq::socket_base_t::socket_base_t (ctx_t *parent_, uint32_t slot_) :
    own_t (parent_, slot_),
    zombie (false),
    destroyed (false),
    last_processing_time (0),
    ticks (0),
    rcvmore (false)
{
}

zmq::socket_base_t::~socket_base_t ()
{
    zmq_assert (zombie && destroyed);

    //  Check whether there are no session leaks.
    sessions_sync.lock ();
    zmq_assert (sessions.empty ());
    sessions_sync.unlock ();
}

zmq::signaler_t *zmq::socket_base_t::get_signaler ()
{
    return &signaler;
}

void zmq::socket_base_t::stop ()
{
    //  Called by ctx when it is terminated (zmq_term).
    //  'stop' command is sent from the threads that called zmq_term to
    //  the thread owning the socket. This way, blocking call in the
    //  owner thread can be interrupted.
    send_stop ();
}

int zmq::socket_base_t::check_protocol (const std::string &protocol_)
{
    //  First check out whether the protcol is something we are aware of.
    if (protocol_ != "inproc" && protocol_ != "ipc" && protocol_ != "tcp" &&
          protocol_ != "pgm" && protocol_ != "epgm") {
        errno = EPROTONOSUPPORT;
        return -1;
    }

    //  If 0MQ is not compiled with OpenPGM, pgm and epgm transports
    //  are not avaialble.
#if !defined ZMQ_HAVE_OPENPGM
    if (protocol_ == "pgm" || protocol_ == "epgm") {
        errno = EPROTONOSUPPORT;
        return -1;
    }
#endif

    //  IPC transport is not available on Windows and OpenVMS.
#if defined ZMQ_HAVE_WINDOWS || defined ZMQ_HAVE_OPENVMS
    if (protocol_ != "ipc") {
        //  Unknown protocol.
        errno = EPROTONOSUPPORT;
        return -1;
    }
#endif

    //  Check whether socket type and transport protocol match.
    //  Specifically, multicast protocols can't be combined with
    //  bi-directional messaging patterns (socket types).
    if ((protocol_ == "pgm" || protocol_ == "epgm") &&
          options.requires_in && options.requires_out) {
        errno = ENOCOMPATPROTO;
        return -1;
    }

    //  Protocol is available.
    return 0;
}

void zmq::socket_base_t::attach_pipes (class reader_t *inpipe_,
    class writer_t *outpipe_, const blob_t &peer_identity_)
{
    // If the peer haven't specified it's identity, let's generate one.
    if (peer_identity_.size ()) {
        xattach_pipes (inpipe_, outpipe_, peer_identity_);
    }
    else {
        blob_t identity (1, 0);
        identity.append (uuid_t ().to_blob (), uuid_t::uuid_blob_len);
        xattach_pipes (inpipe_, outpipe_, identity);
    }
}

int zmq::socket_base_t::setsockopt (int option_, const void *optval_,
    size_t optvallen_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  First, check whether specific socket type overloads the option.
    int rc = xsetsockopt (option_, optval_, optvallen_);
    if (rc == 0 || errno != EINVAL)
        return rc;

    //  If the socket type doesn't support the option, pass it to
    //  the generic option parser.
    return options.setsockopt (option_, optval_, optvallen_);
}

int zmq::socket_base_t::getsockopt (int option_, void *optval_,
    size_t *optvallen_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    if (option_ == ZMQ_RCVMORE) {
        if (*optvallen_ < sizeof (int64_t)) {
            errno = EINVAL;
            return -1;
        }
        *((int64_t*) optval_) = rcvmore ? 1 : 0;
        *optvallen_ = sizeof (int64_t);
        return 0;
    }

    if (option_ == ZMQ_FD) {
        if (*optvallen_ < sizeof (fd_t)) {
            errno = EINVAL;
            return -1;
        }
        *((fd_t*) optval_) = signaler.get_fd ();
        *optvallen_ = sizeof (fd_t);
        return 0;
    }

    if (option_ == ZMQ_EVENTS) {
        if (*optvallen_ < sizeof (uint32_t)) {
            errno = EINVAL;
            return -1;
        }
        process_commands (false, false);
        *((uint32_t*) optval_) = 0;
        if (has_out ())
            *((uint32_t*) optval_) |= ZMQ_POLLOUT;
        if (has_in ())
            *((uint32_t*) optval_) |= ZMQ_POLLIN;
        *optvallen_ = sizeof (uint32_t);
        return 0;
    }

    return options.getsockopt (option_, optval_, optvallen_);
}

int zmq::socket_base_t::bind (const char *addr_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  Parse addr_ string.
    std::string protocol;
    std::string address;
    {
        std::string addr (addr_);
        std::string::size_type pos = addr.find ("://");
        if (pos == std::string::npos) {
            errno = EINVAL;
            return -1;
        }
        protocol = addr.substr (0, pos);
        address = addr.substr (pos + 3);
    }

    int rc = check_protocol (protocol);
    if (rc != 0)
        return -1;

    if (protocol == "inproc")
        return register_endpoint (address.c_str (), this);

    if (protocol == "tcp" || protocol == "ipc") {
        zmq_listener_t *listener = new (std::nothrow) zmq_listener_t (
            choose_io_thread (options.affinity), this, options);
        zmq_assert (listener);
        int rc = listener->set_address (protocol.c_str(), address.c_str ());
        if (rc != 0) {
            delete listener;
            return -1;
        }
        launch_child (listener);

        return 0;
    }

    if (protocol == "pgm" || protocol == "epgm") {

        //  For convenience's sake, bind can be used interchageable with
        //  connect for PGM and EPGM transports.
        return connect (addr_); 
    }

    zmq_assert (false);
    return -1;
}

int zmq::socket_base_t::connect (const char *addr_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  Parse addr_ string.
    std::string protocol;
    std::string address;
    {
        std::string addr (addr_);
        std::string::size_type pos = addr.find ("://");
        if (pos == std::string::npos) {
            errno = EINVAL;
            return -1;
        }
        protocol = addr.substr (0, pos);
        address = addr.substr (pos + 3);
    }

    int rc = check_protocol (protocol);
    if (rc != 0)
        return -1;

    if (protocol == "inproc") {

        //  TODO: inproc connect is specific with respect to creating pipes
        //  as there's no 'reconnect' functionality implemented. Once that
        //  is in place we should follow generic pipe creation algorithm.

        //  Find the peer socket.
        socket_base_t *peer = find_endpoint (address.c_str ());
        if (!peer)
            return -1;

        reader_t *inpipe_reader = NULL;
        writer_t *inpipe_writer = NULL;
        reader_t *outpipe_reader = NULL;
        writer_t *outpipe_writer = NULL;
 
        //  Create inbound pipe, if required.
        if (options.requires_in)
            create_pipe (this, peer, options.hwm, options.swap,
                &inpipe_reader, &inpipe_writer);

        //  Create outbound pipe, if required.
        if (options.requires_out)
            create_pipe (peer, this, options.hwm, options.swap,
                &outpipe_reader, &outpipe_writer);

        //  Attach the pipes to this socket object.
        attach_pipes (inpipe_reader, outpipe_writer, blob_t ());

        //  Attach the pipes to the peer socket. Note that peer's seqnum
        //  was incremented in find_endpoint function. We don't need it
        //  increased here.
        send_bind (peer, outpipe_reader, inpipe_writer,
            options.identity, false);

        return 0;
    }

    //  Create session.
    connect_session_t *session = new (std::nothrow) connect_session_t (
        choose_io_thread (options.affinity), this, options,
        protocol.c_str (), address.c_str ());
    zmq_assert (session);

    //  If 'immediate connect' feature is required, we'll create the pipes
    //  to the session straight away. Otherwise, they'll be created by the
    //  session once the connection is established.
    if (options.immediate_connect) {

        reader_t *inpipe_reader = NULL;
        writer_t *inpipe_writer = NULL;
        reader_t *outpipe_reader = NULL;
        writer_t *outpipe_writer = NULL;

        //  Create inbound pipe, if required.
        if (options.requires_in)
            create_pipe (this, session, options.hwm, options.swap,
                &inpipe_reader, &inpipe_writer);

        //  Create outbound pipe, if required.
        if (options.requires_out)
            create_pipe (session, this, options.hwm, options.swap,
                &outpipe_reader, &outpipe_writer);

        //  Attach the pipes to the socket object.
        attach_pipes (inpipe_reader, outpipe_writer, blob_t ());

        //  Attach the pipes to the session object.
        session->attach_pipes (outpipe_reader, inpipe_writer, blob_t ());
    }

    //  Activate the session. Make it a child of this socket.
    launch_child (session);

    return 0;
}

int zmq::socket_base_t::send (::zmq_msg_t *msg_, int flags_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  Process pending commands, if any.
    process_commands (false, true);
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  At this point we impose the MORE flag on the message.
    if (flags_ & ZMQ_SNDMORE)
        msg_->flags |= ZMQ_MSG_MORE;

    //  Try to send the message.
    int rc = xsend (msg_, flags_);
    if (rc == 0)
        return 0;

    //  In case of non-blocking send we'll simply propagate
    //  the error - including EAGAIN - upwards.
    if (flags_ & ZMQ_NOBLOCK)
        return -1;

    //  Oops, we couldn't send the message. Wait for the next
    //  command, process it and try to send the message again.
    while (rc != 0) {
        if (errno != EAGAIN)
            return -1;
        process_commands (true, false);
        if (unlikely (zombie)) {
            errno = ETERM;
            return -1;
        }
        rc = xsend (msg_, flags_);
    }
    return 0;
}

int zmq::socket_base_t::recv (::zmq_msg_t *msg_, int flags_)
{
    if (unlikely (zombie)) {
        errno = ETERM;
        return -1;
    }

    //  Get the message.
    int rc = xrecv (msg_, flags_);
    int err = errno;

    //  Once every inbound_poll_rate messages check for signals and process
    //  incoming commands. This happens only if we are not polling altogether
    //  because there are messages available all the time. If poll occurs,
    //  ticks is set to zero and thus we avoid this code.
    //
    //  Note that 'recv' uses different command throttling algorithm (the one
    //  described above) from the one used by 'send'. This is because counting
    //  ticks is more efficient than doing rdtsc all the time.
    if (++ticks == inbound_poll_rate) {
        process_commands (false, false);
        if (unlikely (zombie)) {
            errno = ETERM;
            return -1;
        }
        ticks = 0;
    }

    //  If we have the message, return immediately.
    if (rc == 0) {
        rcvmore = msg_->flags & ZMQ_MSG_MORE;
        if (rcvmore)
            msg_->flags &= ~ZMQ_MSG_MORE;
        return 0;
    }

    //  If we don't have the message, restore the original cause of the problem.
    errno = err;

    //  If the message cannot be fetched immediately, there are two scenarios.
    //  For non-blocking recv, commands are processed in case there's a revive
    //  command already waiting int a command pipe. If it's not, return EAGAIN.
    if (flags_ & ZMQ_NOBLOCK) {
        if (errno != EAGAIN)
            return -1;
        process_commands (false, false);
        if (unlikely (zombie)) {
            errno = ETERM;
            return -1;
        }
        ticks = 0;

        rc = xrecv (msg_, flags_);
        if (rc == 0) {
            rcvmore = msg_->flags & ZMQ_MSG_MORE;
            if (rcvmore)
                msg_->flags &= ~ZMQ_MSG_MORE;
        }
        return rc;
    }

    //  In blocking scenario, commands are processed over and over again until
    //  we are able to fetch a message.
    while (rc != 0) {
        if (errno != EAGAIN)
            return -1;
        process_commands (true, false);
        if (unlikely (zombie)) {
            errno = ETERM;
            return -1;
        }
        rc = xrecv (msg_, flags_);
        ticks = 0;
    }

    rcvmore = msg_->flags & ZMQ_MSG_MORE;
    if (rcvmore)
        msg_->flags &= ~ZMQ_MSG_MORE;
    return 0;
}

int zmq::socket_base_t::close ()
{
    zmq_assert (!zombie);

    //  Socket becomes a zombie. From now on all new arrived pipes (bind
    //  command) are immediately terminated.
    zombie = true;

    //  Start termination of associated I/O object hierarchy.
    terminate ();

    //  Ask context to zombify this socket. In other words, transfer
    //  the ownership of the socket from this application thread
    //  to the context which will take care of the rest of shutdown process.
    zombify_socket (this);

    return 0;
}

bool zmq::socket_base_t::has_in ()
{
    return xhas_in ();
}

bool zmq::socket_base_t::has_out ()
{
    return xhas_out ();
}

bool zmq::socket_base_t::register_session (const blob_t &name_,
    session_t *session_)
{
    sessions_sync.lock ();
    bool registered = sessions.insert (
        std::make_pair (name_, session_)).second;
    sessions_sync.unlock ();
    return registered;
}

void zmq::socket_base_t::unregister_session (const blob_t &name_)
{
    sessions_sync.lock ();
    sessions_t::iterator it = sessions.find (name_);
    zmq_assert (it != sessions.end ());
    sessions.erase (it);
    sessions_sync.unlock ();
}

zmq::session_t *zmq::socket_base_t::find_session (const blob_t &name_)
{
    sessions_sync.lock ();
    sessions_t::iterator it = sessions.find (name_);
    if (it == sessions.end ()) {
        sessions_sync.unlock ();
        return NULL;
    }
    session_t *session = it->second;

    //  Prepare the session for subsequent attach command.
    session->inc_seqnum ();

    sessions_sync.unlock ();
    return session;    
}

bool zmq::socket_base_t::dezombify ()
{
    zmq_assert (zombie);

    //  Process any commands from other threads/sockets that may be available
    //  at the moment. Ultimately, socket will be destroyed.
    process_commands (false, false);

    //  If the object was already marked as destroyed, finish the deallocation.
    if (destroyed) {
        own_t::process_destroy ();
        return true;
    }

    return false;
}

void zmq::socket_base_t::process_commands (bool block_, bool throttle_)
{
    bool received;
    command_t cmd;
    if (block_) {
        received = signaler.recv (&cmd, true);
        zmq_assert (received);
    }
    else {

#if defined ZMQ_DELAY_COMMANDS
        //  Optimised version of command processing - it doesn't have to check
        //  for incoming commands each time. It does so only if certain time
        //  elapsed since last command processing. Command delay varies
        //  depending on CPU speed: It's ~1ms on 3GHz CPU, ~2ms on 1.5GHz CPU
        //  etc. The optimisation makes sense only on platforms where getting
        //  a timestamp is a very cheap operation (tens of nanoseconds).
        if (throttle_) {

            //  Get timestamp counter.
#if defined __GNUC__
            uint32_t low;
            uint32_t high;
            __asm__ volatile ("rdtsc" : "=a" (low), "=d" (high));
            uint64_t current_time = (uint64_t) high << 32 | low;
#elif defined _MSC_VER
            uint64_t current_time = __rdtsc ();
#else
#error
#endif

            //  Check whether certain time have elapsed since last command
            //  processing.
            if (current_time - last_processing_time <= max_command_delay)
                return;
            last_processing_time = current_time;
        }
#endif

        //  Check whether there are any commands pending for this thread.
        received = signaler.recv (&cmd, false);
    }

    //  Process all the commands available at the moment.
    while (received) {
        cmd.destination->process_command (cmd);
        received = signaler.recv (&cmd, false);
    }
}

void zmq::socket_base_t::process_stop ()
{
    //  Here, someone have called zmq_term while the socket was still alive.
    //  We'll zombify it so that any blocking call is interrupted and any
    //  further attempt to use the socket will return ETERM. The user is still
    //  responsible for calling zmq_close on the socket though!
    zombie = true;
}

void zmq::socket_base_t::process_bind (reader_t *in_pipe_, writer_t *out_pipe_,
    const blob_t &peer_identity_)
{
    //  If the socket is already being shut down, the termination process on
    //  the new pipes is started immediately. However, they are still attached
    //  as to let the process finish in a decent manner.
    if (unlikely (zombie)) {
        if (in_pipe_)
            in_pipe_->terminate ();
        if (out_pipe_)
            out_pipe_->terminate ();
    }

    attach_pipes (in_pipe_, out_pipe_, peer_identity_);
}

void zmq::socket_base_t::process_unplug ()
{
}

void zmq::socket_base_t::process_term ()
{
    zmq_assert (zombie);

    //  Unregister all inproc endpoints associated with this socket.
    //  Doing this we make sure that no new pipes from other sockets (inproc)
    //  will be initiated.
    unregister_endpoints (this);

    //  Continue the termination process immediately.
    own_t::process_term ();
}

void zmq::socket_base_t::process_destroy ()
{
    destroyed = true;
}

int zmq::socket_base_t::xsetsockopt (int option_, const void *optval_,
    size_t optvallen_)
{
    errno = EINVAL;
    return -1;
}

bool zmq::socket_base_t::xhas_out ()
{
    return false;
}

int zmq::socket_base_t::xsend (zmq_msg_t *msg_, int options_)
{
    errno = ENOTSUP;
    return -1;
}

bool zmq::socket_base_t::xhas_in ()
{
    return false;
}

int zmq::socket_base_t::xrecv (zmq_msg_t *msg_, int options_)
{
    errno = ENOTSUP;
    return -1;
}