Add SWAP support

src/Makefile.am

@@ -76,6 +76,7 @@ libzmq_la_SOURCES = app_thread.hpp \
     lb.hpp \
     likely.hpp \
     msg_content.hpp \
+    msg_store.hpp \
     mutex.hpp \
     object.hpp \
     options.hpp \
@@ -134,6 +135,7 @@ libzmq_la_SOURCES = app_thread.hpp \
     ip.cpp \
     kqueue.cpp \
     lb.cpp \
+    msg_store.cpp \
     object.cpp \
     options.cpp \
     owned.cpp \

src/msg_store.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 "../include/zmq.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sstream>
+#include <algorithm>
+
+#ifdef ZMQ_HAVE_WINDOWS
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
+#include "atomic_counter.hpp"
+#include "msg_store.hpp"
+#include "err.hpp"
+
+zmq::msg_store_t::msg_store_t (int64_t filesize_, size_t block_size_) :
+    fd (-1),
+    filesize (filesize_),
+    file_pos (0),
+    write_pos (0),
+    read_pos (0),
+    block_size (block_size_),
+    write_buf_start_addr (0)
+{
+    zmq_assert (filesize > 0);
+    zmq_assert (block_size > 0);
+
+    buf1 = new (std::nothrow) char [block_size];
+    zmq_assert (buf1);
+
+    buf2 = new (std::nothrow) char [block_size];
+    zmq_assert (buf2);
+
+    read_buf = write_buf = buf1;
+}
+
+zmq::msg_store_t::~msg_store_t ()
+{
+    delete [] buf1;
+    delete [] buf2;
+
+    if (fd == -1)
+        return;
+
+#ifdef ZMQ_HAVE_WINDOWS
+    int rc = _close (fd);
+#else
+    int rc = close (fd);
+#endif
+    errno_assert (rc == 0);
+
+#ifdef ZMQ_HAVE_WINDOWS
+    rc = _unlink (filename.c_str ());
+#else
+    rc = unlink (filename.c_str ());
+#endif
+    errno_assert (rc == 0);
+}
+
+int zmq::msg_store_t::init ()
+{
+    static zmq::atomic_counter_t seqnum (0);
+
+    //  Get process ID.
+#ifdef ZMQ_HAVE_WINDOWS
+    int pid = GetCurrentThreadId ();
+#else
+    pid_t pid = getpid ();
+#endif
+
+    std::ostringstream outs;
+    outs << "zmq_" << pid << '_' << seqnum.get () << ".swap";
+    filename = outs.str ();
+
+    seqnum.add (1);
+
+    //  Open the backing file.
+#ifdef ZMQ_HAVE_WINDOWS
+    fd = _open (filename.c_str (), _O_RDWR | _O_CREAT, 0600);
+#else
+    fd = open (filename.c_str (), O_RDWR | O_CREAT, 0600);
+#endif
+    if (fd == -1)
+        return -1;
+
+#ifdef ZMQ_HAVE_LINUX
+    //  Enable more aggresive read-ahead optimization.
+    posix_fadvise (fd, 0, filesize, POSIX_FADV_SEQUENTIAL);
+#endif
+    return 0;
+}
+
+bool zmq::msg_store_t::store (zmq_msg_t *msg_)
+{
+    size_t msg_size = zmq_msg_size (msg_);
+
+    //  Check buffer space availability.
+    //  NOTE: We always keep one byte open.
+    if (buffer_space () <= (int64_t) (sizeof msg_size + 1 + msg_size))
+        return false;
+
+    //  Don't store the ZMQ_MSG_SHARED flag.
+    uint8_t msg_flags = msg_->flags & ~ZMQ_MSG_SHARED;
+
+    //  Write message length, flags, and message body.
+    copy_to_file (&msg_size, sizeof msg_size);
+    copy_to_file (&msg_flags, sizeof msg_flags);
+    copy_to_file (zmq_msg_data (msg_), msg_size);
+
+    zmq_msg_close (msg_);
+
+    return true;
+}
+
+void zmq::msg_store_t::fetch (zmq_msg_t *msg_)
+{
+    //  There must be at least one message available.
+    zmq_assert (read_pos != write_pos);
+
+    //  Retrieve the message size.
+    size_t msg_size;
+    copy_from_file (&msg_size, sizeof msg_size);
+
+    //  Initialize the message.
+    zmq_msg_init_size (msg_, msg_size);
+
+    //  Retrieve the message flags.
+    copy_from_file (&msg_->flags, sizeof msg_->flags);
+
+    //  Retrieve the message payload.
+    copy_from_file (zmq_msg_data (msg_), msg_size);
+}
+
+void zmq::msg_store_t::commit ()
+{
+    commit_pos = write_pos;
+}
+
+void zmq::msg_store_t::rollback ()
+{
+    if (commit_pos == write_pos || read_pos == write_pos)
+        return;
+
+
+    if (write_pos > read_pos)
+        zmq_assert (read_pos <= commit_pos && commit_pos <= write_pos);
+    else
+        zmq_assert (read_pos <= commit_pos || commit_pos <= write_pos);
+
+    if (commit_pos / block_size == read_pos / block_size) {
+        write_buf_start_addr = commit_pos % block_size;
+        write_buf = read_buf;
+    }
+    else if (commit_pos / block_size != write_pos / block_size) {
+        write_buf_start_addr = commit_pos % block_size;
+        fill_buf (write_buf, write_buf_start_addr);
+    }
+
+    write_pos = commit_pos;
+}
+
+bool zmq::msg_store_t::empty ()
+{
+    return read_pos == write_pos;
+}
+
+bool zmq::msg_store_t::full ()
+{
+    return buffer_space () == 1;
+}
+
+void zmq::msg_store_t::copy_from_file (void *buffer_, size_t count_)
+{
+    char *ptr = (char*) buffer_;
+    size_t n, n_left = count_;
+
+    while (n_left > 0) {
+
+        n = std::min (n_left, std::min ((size_t) (filesize - read_pos),
+            (size_t) (block_size - read_pos % block_size)));
+
+        memcpy (ptr, &read_buf [read_pos % block_size], n);
+        ptr += n;
+
+        read_pos = (read_pos + n) % filesize;
+        if (read_pos % block_size == 0) {
+            if (read_pos / block_size == write_pos / block_size)
+                read_buf = write_buf;
+            else
+                fill_buf (read_buf, read_pos);
+        }
+
+        n_left -= n;
+    }
+}
+
+void zmq::msg_store_t::copy_to_file (const void *buffer_, size_t count_)
+{
+    char *ptr = (char*) buffer_;
+    size_t n, n_left = count_;
+
+    while (n_left > 0) {
+
+        n = std::min (n_left, std::min ((size_t) (filesize - write_pos),
+            (size_t) (block_size - write_pos % block_size)));
+
+        memcpy (&write_buf [write_pos % block_size], ptr, n);
+        ptr += n;
+
+        write_pos = (write_pos + n) % filesize;
+        if (write_pos % block_size == 0) {
+
+            save_write_buf ();
+            write_buf_start_addr = write_pos;
+
+            if (write_buf == read_buf) {
+                if (read_buf == buf2)
+                    write_buf = buf1;
+                else
+                    write_buf = buf2;
+            }
+        }
+
+        n_left -= n;
+    }
+}
+
+void zmq::msg_store_t::fill_buf (char *buf, int64_t pos)
+{
+    if (file_pos != pos) {
+#ifdef ZMQ_HAVE_WINDOWS
+        __int64 offset = _lseeki64 (fd, pos, SEEK_SET);
+#else
+        off_t offset = lseek (fd, (off_t) pos, SEEK_SET);
+#endif
+        errno_assert (offset == pos);
+        file_pos = pos;
+    }
+
+    size_t i = 0;
+    size_t n = std::min (block_size, (size_t) (filesize - file_pos));
+
+    while (i < n) {
+#ifdef ZMQ_HAVE_WINDOWS
+        int rc = _read (fd, &buf [i], n - i);
+#else
+        ssize_t rc = read (fd, &buf [i], n - i);
+#endif
+        errno_assert (rc > 0);
+        i += rc;
+    }
+
+    file_pos += n;
+}
+
+void zmq::msg_store_t::save_write_buf ()
+{
+    if (file_pos != write_buf_start_addr) {
+#ifdef ZMQ_HAVE_WINDOWS
+        __int64 offset = _lseeki64 (fd, write_buf_start_addr, SEEK_SET);
+#else
+        off_t offset = lseek (fd, (off_t) write_buf_start_addr, SEEK_SET);
+#endif
+        errno_assert (offset == write_buf_start_addr);
+        file_pos = write_buf_start_addr;
+    }
+
+    size_t i = 0;
+    size_t n = std::min (block_size, (size_t) (filesize - file_pos));
+
+    while (i < n) {
+#ifdef ZMQ_HAVE_WINDOWS
+        int rc = _write (fd, &write_buf [i], n - i);
+#else
+        ssize_t rc = write (fd, &write_buf [i], n - i);
+#endif
+        errno_assert (rc > 0);
+        i += rc;
+    }
+
+    file_pos += n;
+}
+
+int64_t zmq::msg_store_t::buffer_space ()
+{
+    if (write_pos < read_pos)
+        return read_pos - write_pos;
+
+    return filesize - (write_pos - read_pos);
+}

src/msg_store.hpp

+/*
+    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/>.
+*/
+
+#ifndef __ZMQ_MSG_STORE_HPP_INCLUDED__
+#define __ZMQ_MSG_STORE_HPP_INCLUDED__
+
+#include "../include/zmq.h"
+
+#include <string>
+#include "stdint.hpp"
+
+namespace zmq
+{
+
+    //  This class implements a message store. Messages are retrieved from
+    //  the store in the same order as they entered it.
+
+    class msg_store_t
+    {
+    public:
+
+        enum { default_block_size = 8192 };
+
+        //  Creates message store.
+        msg_store_t (int64_t filesize_, size_t block_size_ = default_block_size);
+
+        ~msg_store_t ();
+
+        int init ();
+
+        //  Stores the message into the message store. The function
+        //  returns false if the message store is full; true otherwise.
+        bool store (zmq_msg_t *msg_);
+
+        //  Fetches the oldest message from the message store. It is an error
+        //  to call this function when the message store is empty.
+        void fetch (zmq_msg_t *msg_);
+
+        void commit ();
+
+        void rollback ();
+
+        //  Returns true if the message store is empty; false otherwise.
+        bool empty ();
+
+        //  Returns true if and only if the store is full.
+        bool full ();
+
+    private:
+
+        //  Copies data from a memory buffer to the backing file.
+        //  Wraps around when reaching maximum file size.
+        void copy_from_file (void *buffer_, size_t count_);
+
+        //  Copies data from the backing file to the memory buffer.
+        //  Wraps around when reaching end-of-file.
+        void copy_to_file (const void *buffer_, size_t count_);
+
+        //  Returns the buffer space available.
+        int64_t buffer_space ();
+
+        void fill_buf (char *buf, int64_t pos);
+
+        void save_write_buf ();
+
+        //  File descriptor to the backing file.
+        int fd;
+
+        //  Name of the backing file.
+        std::string filename;
+
+        //  Maximum size of the backing file.
+        int64_t filesize;
+
+        //  File offset associated with the fd file descriptor.
+        int64_t file_pos;
+
+        //  File offset the next message will be stored at.
+        int64_t write_pos;
+
+        //  File offset the next message will be read from.
+        int64_t read_pos;
+
+        int64_t commit_pos;
+
+        size_t block_size;
+
+        char *buf1;
+        char *buf2;
+        char *read_buf;
+        char *write_buf;
+
+        int64_t write_buf_start_addr;
+    };
+
+}
+
+#endif

src/pipe.cpp

@@ -21,20 +21,14 @@
 
 #include "pipe.hpp"
 
-zmq::reader_t::reader_t (object_t *parent_,
-      uint64_t hwm_, uint64_t lwm_) :
+zmq::reader_t::reader_t (object_t *parent_, uint64_t lwm_) :
     object_t (parent_),
     pipe (NULL),
     peer (NULL),
-    hwm (hwm_),
     lwm (lwm_),
     msgs_read (0),
     endpoint (NULL)
-{
-    //  Adjust lwm and hwm.
-    if (lwm == 0 || lwm > hwm)
-        lwm = hwm;
-}
+{}
 
 zmq::reader_t::~reader_t ()
 {
@@ -113,20 +107,28 @@ void zmq::reader_t::process_pipe_term_ack ()
 }
 
 zmq::writer_t::writer_t (object_t *parent_,
-      uint64_t hwm_, uint64_t lwm_) :
+      uint64_t hwm_, int64_t swap_size_) :
     object_t (parent_),
     pipe (NULL),
     peer (NULL),
     hwm (hwm_),
-    lwm (lwm_),
     msgs_read (0),
     msgs_written (0),
+    msg_store (NULL),
+    extra_msg_flag (false),
     stalled (false),
+    pending_close (false),
     endpoint (NULL)
 {
-    //  Adjust lwm and hwm.
-    if (lwm == 0 || lwm > hwm)
-        lwm = hwm;
+    if (swap_size_ > 0) {
+        msg_store = new (std::nothrow) msg_store_t (swap_size_);
+        if (msg_store != NULL) {
+            if (msg_store->init () < 0) {
+                delete msg_store;
+                msg_store = NULL;
+            }
+        }
+    }
 }
 
 void zmq::writer_t::set_endpoint (i_endpoint *endpoint_)
@@ -136,6 +138,10 @@ void zmq::writer_t::set_endpoint (i_endpoint *endpoint_)
 
 zmq::writer_t::~writer_t ()
 {
+    if (extra_msg_flag)
+        zmq_msg_close (&extra_msg);
+
+    delete msg_store;
 }
 
 void zmq::writer_t::set_pipe (pipe_t *pipe_)
@@ -147,7 +153,7 @@ void zmq::writer_t::set_pipe (pipe_t *pipe_)
 
 bool zmq::writer_t::check_write ()
 {
-    if (pipe_full ()) {
+    if (pipe_full () && (msg_store == NULL || msg_store->full () || extra_msg_flag)) {
         stalled = true;
         return false;
     }
@@ -157,28 +163,45 @@ bool zmq::writer_t::check_write ()
 
 bool zmq::writer_t::write (zmq_msg_t *msg_)
 {
-    if (pipe_full ()) {
-        stalled = true;
+    if (!check_write ())
         return false;
+
+    if (pipe_full ()) {
+        if (msg_store->store (msg_)) {
+            if (!(msg_->flags & ZMQ_MSG_MORE))
+                msg_store->commit ();
+        } else {
+            extra_msg = *msg_;
+            extra_msg_flag = true;
+        }
+    }
+    else {
+        pipe->write (*msg_, msg_->flags & ZMQ_MSG_MORE);
+        if (!(msg_->flags & ZMQ_MSG_MORE))
+            msgs_written++;
     }
 
-    pipe->write (*msg_, msg_->flags & ZMQ_MSG_MORE);
-    if (!(msg_->flags & ZMQ_MSG_MORE))
-        msgs_written++;
     return true;
 }
 
 void zmq::writer_t::rollback ()
 {
-    zmq_msg_t msg;
+    if (extra_msg_flag && extra_msg.flags & ZMQ_MSG_MORE) {
+        zmq_msg_close (&extra_msg);
+        extra_msg_flag = false;
+    }
+
+    if (msg_store != NULL)
+        msg_store->rollback ();
 
+    zmq_msg_t msg;
     //  Remove all incomplete messages from the pipe.
     while (pipe->unwrite (&msg)) {
         zmq_assert (msg.flags & ZMQ_MSG_MORE);
         zmq_msg_close (&msg);
     }
 
-    if (stalled && endpoint != NULL && !pipe_full()) {
+    if (stalled && endpoint != NULL && check_write ()) {
         stalled = false;
         endpoint->revive (this);
     }
@@ -197,6 +220,14 @@ void zmq::writer_t::term ()
     //  Rollback any unfinished messages.
     rollback ();
 
+    if (msg_store == NULL || (msg_store->empty () && !extra_msg_flag))
+        write_delimiter ();
+    else
+        pending_close = true;
+}
+
+void zmq::writer_t::write_delimiter ()
+{
     //  Push delimiter into the pipe.
     //  Trick the compiler to belive that the tag is a valid pointer.
     zmq_msg_t msg;
@@ -209,7 +240,42 @@ void zmq::writer_t::term ()
 
 void zmq::writer_t::process_reader_info (uint64_t msgs_read_)
 {
+    zmq_msg_t msg;
+
     msgs_read = msgs_read_;
+    if (msg_store) {
+
+        //  Move messages from backing store into pipe.
+        while (!pipe_full () && !msg_store->empty ()) {
+            msg_store->fetch(&msg);
+            //  Write message into the pipe.
+            pipe->write (msg, msg.flags & ZMQ_MSG_MORE);
+            if (!(msg.flags & ZMQ_MSG_MORE))
+                msgs_written++;
+        }
+
+        if (extra_msg_flag) {
+            if (!pipe_full ()) {
+                pipe->write (extra_msg, extra_msg.flags & ZMQ_MSG_MORE);
+                if (!(extra_msg.flags & ZMQ_MSG_MORE))
+                    msgs_written++;
+                extra_msg_flag = false;
+            }
+            else if (msg_store->store (&extra_msg)) {
+                if (!(extra_msg.flags & ZMQ_MSG_MORE))
+                    msg_store->commit ();
+                extra_msg_flag = false;
+            }
+        }
+
+        if (pending_close && msg_store->empty () && !extra_msg_flag) {
+            write_delimiter ();
+            pending_close = false;
+        }
+
+        flush ();
+    }
+
     if (stalled && endpoint != NULL) {
         stalled = false;
         endpoint->revive (this);
@@ -232,9 +298,9 @@ bool zmq::writer_t::pipe_full ()
 }
 
 zmq::pipe_t::pipe_t (object_t *reader_parent_, object_t *writer_parent_,
-      uint64_t hwm_) :
-    reader (reader_parent_, hwm_, compute_lwm (hwm_)),
-    writer (writer_parent_, hwm_, compute_lwm (hwm_))
+      uint64_t hwm_, int64_t swap_size_) :
+    reader (reader_parent_, compute_lwm (hwm_)),
+    writer (writer_parent_, hwm_, swap_size_)
 {
     reader.set_pipe (this);
     writer.set_pipe (this);

src/pipe.hpp

@@ -26,6 +26,7 @@
 #include "i_endpoint.hpp"
 #include "yarray_item.hpp"
 #include "ypipe.hpp"
+#include "msg_store.hpp"
 #include "config.hpp"
 #include "object.hpp"
 
@@ -36,8 +37,7 @@ namespace zmq
     {
     public:
 
-        reader_t (class object_t *parent_,
-            uint64_t hwm_, uint64_t lwm_);
+        reader_t (class object_t *parent_, uint64_t lwm_);
         ~reader_t ();
 
         void set_pipe (class pipe_t *pipe_);
@@ -64,8 +64,7 @@ namespace zmq
         //  Pipe writer associated with the other side of the pipe.
         class writer_t *peer;
 
-        //  High and low watermarks for in-memory storage (in bytes).
-        uint64_t hwm;
+        //  Low watermark for in-memory storage (in bytes).
         uint64_t lwm;
 
         //  Number of messages read so far.
@@ -82,8 +81,7 @@ namespace zmq
     {
     public:
 
-        writer_t (class object_t *parent_,
-            uint64_t hwm_, uint64_t lwm_);
+        writer_t (class object_t *parent_, uint64_t hwm_, int64_t swap_size_);
         ~writer_t ();
 
         void set_pipe (class pipe_t *pipe_);
@@ -117,15 +115,18 @@ namespace zmq
         //  Tests whether the pipe is already full.
         bool pipe_full ();
 
+        //  Write special message to the pipe so that the reader
+        //  can find out we are finished.
+        void write_delimiter ();
+
         //  The underlying pipe.
         class pipe_t *pipe;
 
         //  Pipe reader associated with the other side of the pipe.
         class reader_t *peer;
 
-        //  High and low watermarks for in-memory storage (in bytes).
+        //  High watermark for in-memory storage (in bytes).
         uint64_t hwm;
-        uint64_t lwm;
 
         //  Last confirmed number of messages read from the pipe.
         //  The actual number can be higher.
@@ -134,9 +135,19 @@ namespace zmq
         //  Number of messages we have written so far.
         uint64_t msgs_written;
 
+        //  Pointer to backing store. If NULL, messages are always
+        //  kept in main memory.
+        msg_store_t *msg_store;
+
+        bool extra_msg_flag;
+
+        zmq_msg_t extra_msg;
+
         //  True iff the last attempt to write a message has failed.
         bool stalled;
 
+        bool pending_close;
+
         //  Endpoint (either session or socket) the pipe is attached to.
         i_endpoint *endpoint;
 
@@ -150,7 +161,7 @@ namespace zmq
     public:
 
         pipe_t (object_t *reader_parent_, object_t *writer_parent_,
-            uint64_t hwm_);
+            uint64_t hwm_, int64_t swap_size_);
         ~pipe_t ();
 
         reader_t reader;

src/session.cpp

@@ -265,7 +265,7 @@ void zmq::session_t::process_attach (i_engine *engine_,
     writer_t *socket_writer = NULL;
 
     if (options.requires_in && !out_pipe) {
-        pipe_t *pipe = new (std::nothrow) pipe_t (owner, this, options.hwm);
+        pipe_t *pipe = new (std::nothrow) pipe_t (owner, this, options.hwm, options.swap);
         zmq_assert (pipe);
         out_pipe = &pipe->writer;
         out_pipe->set_endpoint (this);
@@ -273,7 +273,7 @@ void zmq::session_t::process_attach (i_engine *engine_,
     }
 
     if (options.requires_out && !in_pipe) {
-        pipe_t *pipe = new (std::nothrow) pipe_t (this, owner, options.hwm);
+        pipe_t *pipe = new (std::nothrow) pipe_t (this, owner, options.hwm, options.swap);
         zmq_assert (pipe);
         in_pipe = &pipe->reader;
         in_pipe->set_endpoint (this);

src/socket_base.cpp

@@ -195,13 +195,13 @@ int zmq::socket_base_t::connect (const char *addr_)
 
         //  Create inbound pipe, if required.
         if (options.requires_in) {
-            in_pipe = new (std::nothrow) pipe_t (this, peer, options.hwm);
+            in_pipe = new (std::nothrow) pipe_t (this, peer, options.hwm, options.swap);
             zmq_assert (in_pipe);
         }
 
         //  Create outbound pipe, if required.
         if (options.requires_out) {
-            out_pipe = new (std::nothrow) pipe_t (peer, this, options.hwm);
+            out_pipe = new (std::nothrow) pipe_t (peer, this, options.hwm, options.swap);
             zmq_assert (out_pipe);
         }
 
@@ -234,14 +234,14 @@ int zmq::socket_base_t::connect (const char *addr_)
 
         //  Create inbound pipe, if required.
         if (options.requires_in) {
-            in_pipe = new (std::nothrow) pipe_t (this, session, options.hwm);
+            in_pipe = new (std::nothrow) pipe_t (this, session, options.hwm, options.swap);
             zmq_assert (in_pipe);
 
         }
 
         //  Create outbound pipe, if required.
         if (options.requires_out) {
-            out_pipe = new (std::nothrow) pipe_t (session, this, options.hwm);
+            out_pipe = new (std::nothrow) pipe_t (session, this, options.hwm, options.swap);
             zmq_assert (out_pipe);
         }