lock-free polling removed; ZMQ_POLL flag removed

18 files changed, 28 insertions, 801 deletions

diff --git a/doc/zmq_init.txt b/doc/zmq_init.txt
index 9df3e67..c1a5877 100644
--- a/doc/zmq_init.txt
+++ b/doc/zmq_init.txt
@@ -25,12 +25,8 @@ The 'io_threads' argument specifies the size of the 0MQ thread pool to handle
 I/O operations. If your application is using 'inproc' messaging exclusively you
 may set this to zero, otherwise set it to at least one.
 
-The 'flags' argument is a combination of the flags defined below:
-
-*ZMQ_POLL*::
-Specifies that sockets within this 'context' should support multiplexing using
-_zmq_poll()_. Enabling this functionality may add a small amount of latency to
-message transfers compared to leaving it disabled.
+There are no flags defined at the moment and the 'flags' argument should be set
+to zero.
 
 
 RETURN VALUE
diff --git a/include/zmq.h b/include/zmq.h
index e860146..9745adf 100644
--- a/include/zmq.h
+++ b/include/zmq.h
@@ -144,6 +144,7 @@ ZMQ_EXPORT size_t zmq_msg_size (zmq_msg_t *msg);
 /*  0MQ infrastructure (a.k.a. context) initialisation & termination.         */
 /******************************************************************************/
 
+/*  This flag is obsolete and has no effect. To be removed in next version.   */
 #define ZMQ_POLL 1
 
 ZMQ_EXPORT void *zmq_init (int app_threads, int io_threads, int flags);
diff --git a/src/Makefile.am b/src/Makefile.am
index 8cd94dd..837cd5f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -50,7 +50,6 @@ endif
 nodist_libzmq_la_SOURCES = $(pgm_sources)
 
 libzmq_la_SOURCES = app_thread.hpp \
-    atomic_bitmap.hpp \
     atomic_counter.hpp \
     atomic_ptr.hpp \
     blob.hpp \
@@ -74,7 +73,6 @@ libzmq_la_SOURCES = app_thread.hpp \
     i_endpoint.hpp \
     i_engine.hpp \
     i_poll_events.hpp \
-    i_signaler.hpp \
     kqueue.hpp \
     lb.hpp \
     likely.hpp \
@@ -98,7 +96,6 @@ libzmq_la_SOURCES = app_thread.hpp \
     req.hpp \
     select.hpp \
     session.hpp \
-    simple_semaphore.hpp \
     socket_base.hpp \
     stdint.hpp \
     streamer.hpp \
@@ -116,7 +113,6 @@ libzmq_la_SOURCES = app_thread.hpp \
     yarray.hpp \
     yarray_item.hpp \
     ypipe.hpp \
-    ypollset.hpp \
     yqueue.hpp \
     zmq_connecter.hpp \
     zmq_decoder.hpp \
@@ -166,7 +162,6 @@ libzmq_la_SOURCES = app_thread.hpp \
     uuid.cpp \
     xrep.cpp \
     xreq.cpp \
-    ypollset.cpp \
     zmq.cpp \
     zmq_connecter.cpp \
     zmq_decoder.cpp \
diff --git a/src/app_thread.cpp b/src/app_thread.cpp
index 9ff2112..0dad660 100644
--- a/src/app_thread.cpp
+++ b/src/app_thread.cpp
@@ -36,7 +36,6 @@
 #include "app_thread.hpp"
 #include "dispatcher.hpp"
 #include "fd_signaler.hpp"
-#include "ypollset.hpp"
 #include "err.hpp"
 #include "pipe.hpp"
 #include "config.hpp"
@@ -59,27 +58,16 @@
 #define ZMQ_DELAY_COMMANDS
 #endif
 
-zmq::app_thread_t::app_thread_t (dispatcher_t *dispatcher_, int thread_slot_,
-      int flags_) :
+zmq::app_thread_t::app_thread_t (dispatcher_t *dispatcher_, int thread_slot_) :
     object_t (dispatcher_, thread_slot_),
     last_processing_time (0),
     terminated (false)
 {
-    if (flags_ & ZMQ_POLL) {
-        signaler = new (std::nothrow) fd_signaler_t;
-        zmq_assert (signaler);
-    }
-    else {
-        signaler = new (std::nothrow) ypollset_t;
-        zmq_assert (signaler);
-    }
 }
 
 zmq::app_thread_t::~app_thread_t ()
 {
     zmq_assert (sockets.empty ());
-    zmq_assert (signaler);
-    delete signaler;
 }
 
 void zmq::app_thread_t::stop ()
@@ -87,16 +75,16 @@ void zmq::app_thread_t::stop ()
     send_stop ();
 }
 
-zmq::i_signaler *zmq::app_thread_t::get_signaler ()
+zmq::fd_signaler_t *zmq::app_thread_t::get_signaler ()
 {
-    return signaler;
+    return &signaler;
 }
 
 bool zmq::app_thread_t::process_commands (bool block_, bool throttle_)
 {
     uint64_t signals;
     if (block_)
-        signals = signaler->poll ();
+        signals = signaler.poll ();
     else {
 
 #if defined ZMQ_DELAY_COMMANDS
@@ -129,7 +117,7 @@ bool zmq::app_thread_t::process_commands (bool block_, bool throttle_)
 #endif
 
         //  Check whether there are any commands pending for this thread.
-        signals = signaler->check ();
+        signals = signaler.check ();
     }
 
     if (signals) {
diff --git a/src/app_thread.hpp b/src/app_thread.hpp
index 1c2f47a..b7572da 100644
--- a/src/app_thread.hpp
+++ b/src/app_thread.hpp
@@ -25,6 +25,7 @@
 #include "stdint.hpp"
 #include "object.hpp"
 #include "yarray.hpp"
+#include "fd_signaler.hpp"
 
 namespace zmq
 {
@@ -33,8 +34,7 @@ namespace zmq
     {
     public:
 
-        app_thread_t (class dispatcher_t *dispatcher_, int thread_slot_,
-            int flags_);
+        app_thread_t (class dispatcher_t *dispatcher_, int thread_slot_);
 
         ~app_thread_t ();
 
@@ -43,7 +43,7 @@ namespace zmq
         void stop ();
 
         //  Returns signaler associated with this application thread.
-        struct i_signaler *get_signaler ();
+        fd_signaler_t *get_signaler ();
 
         //  Processes commands sent to this thread (if any). If 'block' is
         //  set to true, returns only after at least one command was processed.
@@ -71,7 +71,7 @@ namespace zmq
         sockets_t sockets;
 
         //  App thread's signaler object.
-        struct i_signaler *signaler;
+        fd_signaler_t signaler;
 
         //  Timestamp of when commands were processed the last time.
         uint64_t last_processing_time;
diff --git a/src/atomic_bitmap.hpp b/src/atomic_bitmap.hpp
deleted file mode 100644
index 29bdc13..0000000
--- a/src/atomic_bitmap.hpp
+++ /dev/null
@@ -1,310 +0,0 @@
-/*
-    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_ATOMIC_BITMAP_HPP_INCLUDED__
-#define __ZMQ_ATOMIC_BITMAP_HPP_INCLUDED__
-
-#include "stdint.hpp"
-#include "platform.hpp"
-
-//  These are the conditions to choose between different implementations
-//  of atomic_bitmap.
-
-#if defined ZMQ_FORCE_MUTEXES
-#define ZMQ_ATOMIC_BITMAP_MUTEX
-#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
-#define ZMQ_ATOMIC_BITMAP_X86
-#elif 0 && defined __sparc__ && defined __GNUC__
-#define ZMQ_ATOMIC_BITMAP_SPARC
-#elif defined ZMQ_HAVE_WINDOWS
-#define ZMQ_ATOMIC_BITMAP_WINDOWS
-#elif defined sun
-#define ZMQ_ATOMIC_COUNTER_SUN
-#elif defined( __GNUC__ ) && ( __GNUC__ * 100 + __GNUC_MINOR__ >= 401 )
-#define ZMQ_ATOMIC_COUNTER_GNU
-#else
-#define ZMQ_ATOMIC_BITMAP_MUTEX
-#endif
-
-#if defined ZMQ_ATOMIC_BITMAP_MUTEX
-#include "mutex.hpp"
-#elif defined ZMQ_ATOMIC_BITMAP_WINDOWS
-#include "windows.hpp"
-#elif defined ZMQ_ATOMIC_BITMAP_SUN
-#include <atomic.h>
-#endif
-
-namespace zmq
-{
-
-    //  This class encapuslates several bitwise atomic operations on unsigned
-    //  integer. Selection of operations is driven specifically by the needs
-    //  of ypollset implementation.
-
-    class atomic_bitmap_t
-    {
-    public:
-
-#if (defined ZMQ_ATOMIC_BITMAP_X86 || defined ZMQ_FORCE_MUTEXES) \
-    && defined __x86_64__
-        typedef uint64_t bitmap_t;
-#else
-        typedef uint32_t bitmap_t;
-#endif
-
-        inline atomic_bitmap_t (bitmap_t value_ = 0) :
-            value (value_)
-        {
-        }
-
-        inline ~atomic_bitmap_t ()
-        {
-        }
-
-        //  Bit-test-set-and-reset. Sets one bit of the value and resets
-        //  another one. Returns the original value of the reset bit.
-        inline bool btsr (int set_index_, int reset_index_)
-        {
-#if defined ZMQ_ATOMIC_BITMAP_WINDOWS
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = (oldval | (bitmap_t (1) << set_index_)) &
-                    ~(bitmap_t (1) << reset_index_);
-                if (InterlockedCompareExchange ((volatile LONG*) &value, newval,
-                      oldval) == (LONG) oldval)
-                    return (oldval & (bitmap_t (1) << reset_index_)) ?
-                        true : false;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_GNU
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = (oldval | (bitmap_t (1) << set_index_)) &
-                    ~(bitmap_t (1) << reset_index_);
-                if (__sync_val_compare_and_swap (&value, oldval, newval) == oldval)
-                    return (oldval & (bitmap_t (1) << reset_index_)) ?
-                        true : false;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_SUN
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = (oldval | (bitmap_t (1) << set_index_)) &
-                    ~(bitmap_t (1) << reset_index_);
-                if (atomic_cas_32 (&value, oldval, newval) == oldval)
-                    return (oldval & (bitmap_t (1) << reset_index_)) ?
-                        true : false;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_X86
-            bitmap_t oldval, dummy;
-            __asm__ volatile (
-                "mov %0, %1\n\t"
-                "1:"
-                "mov %1, %2\n\t"
-                "bts %3, %2\n\t"
-                "btr %4, %2\n\t"
-                "lock cmpxchg %2, %0\n\t"
-                "jnz 1b\n\t"
-                : "+m" (value), "=&a" (oldval), "=&r" (dummy)
-                : "r" (bitmap_t(set_index_)), "r" (bitmap_t(reset_index_))
-                : "cc");
-            return (bool) (oldval & (bitmap_t(1) << reset_index_));
-#elif defined ZMQ_ATOMIC_BITMAP_SPARC
-            volatile bitmap_t* valptr = &value;
-            bitmap_t set_val = bitmap_t(1) << set_index_;
-            bitmap_t reset_val = ~(bitmap_t(1) << reset_index_);
-            bitmap_t tmp;
-            bitmap_t oldval;
-            __asm__ volatile(
-                "ld [%5], %2 \n\t"
-                "1: \n\t"
-                "or %2, %0, %3 \n\t"
-                "and %3, %1, %3 \n\t"
-                "cas [%5], %2, %3 \n\t"
-                "cmp %2, %3 \n\t"
-                "bne,a,pn %%icc, 1b \n\t"
-                "mov %3, %2 \n\t"
-                : "+r" (set_val), "+r" (reset_val), "=&r" (tmp),
-                  "=&r" (oldval), "+m" (*valptr)
-                : "r" (valptr)
-                : "cc");
-            return oldval;
-#elif defined ZMQ_ATOMIC_BITMAP_MUTEX
-            sync.lock ();
-            bitmap_t oldval = value;
-            value = (oldval | (bitmap_t (1) << set_index_)) &
-                ~(bitmap_t (1) << reset_index_);
-            sync.unlock ();
-            return (oldval & (bitmap_t (1) << reset_index_)) ? true : false;
-#else
-#error
-#endif
-        }
-
-        //  Sets value to newval. Returns the original value.
-        inline bitmap_t xchg (bitmap_t newval_)
-        {
-            bitmap_t oldval;
-#if defined ZMQ_ATOMIC_BITMAP_WINDOWS
-            oldval = InterlockedExchange ((volatile LONG*) &value, newval_);
-#elif defined ZMQ_ATOMIC_BITMAP_GNU
-            oldval = __sync_lock_test_and_set (&value, newval_);
-#elif defined ZMQ_ATOMIC_BITMAP_SUN
-            oldval = atomic_swap_32 (&value, newval_);
-#elif defined ZMQ_ATOMIC_BITMAP_X86
-            oldval = newval_;
-            __asm__ volatile (
-                "lock; xchg %0, %1"
-                : "=r" (oldval)
-                : "m" (value), "0" (oldval)
-                : "memory");
-#elif defined ZMQ_ATOMIC_BITMAP_SPARC
-            oldval = value;
-            volatile bitmap_t* ptrin = &value;
-            bitmap_t tmp;
-            bitmap_t prev;
-            __asm__ __volatile__(
-                "ld [%4], %1\n\t"
-                "1:\n\t"
-                "mov %0, %2\n\t"
-                "cas [%4], %1, %2\n\t"
-                "cmp %1, %2\n\t"
-                "bne,a,pn %%icc, 1b\n\t"
-                "mov %2, %1\n\t"
-                : "+r" (newval_), "=&r" (tmp), "=&r" (prev), "+m" (*ptrin)
-                : "r" (ptrin)
-                : "cc");
-            return prev;
-#elif defined ZMQ_ATOMIC_BITMAP_MUTEX
-            sync.lock ();
-            oldval = value;
-            value = newval_;
-            sync.unlock ();
-#else
-#error
-#endif
-            return oldval;
-        }
-
-        //  izte is "if-zero-then-else" atomic operation - if the value is zero
-        //  it substitutes it by 'thenval' else it rewrites it by 'elseval'.
-        //  Original value of the integer is returned from this function.
-        inline bitmap_t izte (bitmap_t thenval_,
-            bitmap_t elseval_)
-        {
-#if defined ZMQ_ATOMIC_BITMAP_WINDOWS
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = oldval == 0 ? thenval_ : elseval_;
-                if (InterlockedCompareExchange ((volatile LONG*) &value,
-                      newval, oldval) == (LONG) oldval)
-                    return oldval;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_GNU
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = oldval == 0 ? thenval_ : elseval_;
-                if (__sync_val_compare_and_swap (&value, oldval, newval) == oldval)
-                    return oldval;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_SUN
-            while (true) {
-                bitmap_t oldval = value;
-                bitmap_t newval = oldval == 0 ? thenval_ : elseval_;
-                if (atomic_cas_32 (&value, oldval, newval) == oldval)
-                    return oldval;
-            }
-#elif defined ZMQ_ATOMIC_BITMAP_X86
-            bitmap_t oldval;
-            bitmap_t dummy;
-            __asm__ volatile (
-                "mov %0, %1\n\t"
-                "1:"
-                "mov %3, %2\n\t"
-                "test %1, %1\n\t"
-                "jz 2f\n\t"
-                "mov %4, %2\n\t"
-                "2:"
-                "lock cmpxchg %2, %0\n\t"
-                "jnz 1b\n\t"
-                : "+m" (value), "=&a" (oldval), "=&r" (dummy)
-                : "r" (thenval_), "r" (elseval_)
-                : "cc");
-            return oldval;
-#elif defined ZMQ_ATOMIC_BITMAP_SPARC
-            volatile bitmap_t* ptrin = &value;
-            bitmap_t tmp;
-            bitmap_t prev;
-            __asm__ __volatile__(
-                "ld [%3], %0 \n\t"
-                "mov 0, %1 \n\t"
-                "cas [%3], %1, %4 \n\t"
-                "cmp %0, %1 \n\t"
-                "be,a,pn %%icc,1f \n\t"
-                "ld [%3], %0 \n\t"
-                "cas [%3], %0, %5 \n\t"
-                "1: \n\t"
-                : "=&r" (tmp), "=&r" (prev), "+m" (*ptrin)
-                : "r" (ptrin), "r" (thenval_), "r" (elseval_)
-                : "cc");
-            return prev;
-#elif defined ZMQ_ATOMIC_BITMAP_MUTEX
-            sync.lock ();
-            bitmap_t oldval = value;
-            value = oldval ? elseval_ : thenval_;
-            sync.unlock ();
-            return oldval;
-#else
-#error
-#endif
-        }
-
-    private:
-
-        volatile bitmap_t value;
-#if defined ZMQ_ATOMIC_BITMAP_MUTEX
-        mutex_t sync;
-#endif
-
-        atomic_bitmap_t (const atomic_bitmap_t&);
-        void operator = (const atomic_bitmap_t&);
-    };
-
-}
-
-//  Remove macros local to this file.
-#if defined ZMQ_ATOMIC_BITMAP_WINDOWS
-#undef ZMQ_ATOMIC_BITMAP_WINDOWS
-#endif
-#if defined ZMQ_ATOMIC_BITMAP_GNU
-#undef ZMQ_ATOMIC_BITMAP_GNU
-#endif
-#if defined ZMQ_ATOMIC_BITMAP_SUN
-#undef ZMQ_ATOMIC_BITMAP_SUN
-#endif
-#if defined ZMQ_ATOMIC_BITMAP_X86
-#undef ZMQ_ATOMIC_BITMAP_X86
-#endif
-#if defined ZMQ_ATOMIC_BITMAP_SPARC
-#undef ZMQ_ATOMIC_BITMAP_SPARC
-#endif
-#if defined ZMQ_ATOMIC_BITMAP_MUTEX
-#undef ZMQ_ATOMIC_BITMAP_MUTEX
-#endif
-
-#endif
-
diff --git a/src/dispatcher.cpp b/src/dispatcher.cpp
index a1154de..1e11619 100644
--- a/src/dispatcher.cpp
+++ b/src/dispatcher.cpp
@@ -33,8 +33,7 @@
 #include "windows.h"
 #endif
 
-zmq::dispatcher_t::dispatcher_t (int app_threads_, int io_threads_,
-      int flags_) :
+zmq::dispatcher_t::dispatcher_t (int app_threads_, int io_threads_) :
     sockets (0),
     terminated (false)
 {
@@ -53,7 +52,7 @@ zmq::dispatcher_t::dispatcher_t (int app_threads_, int io_threads_,
     for (int i = 0; i != app_threads_; i++) {
         app_thread_info_t info;
         info.associated = false;
-        info.app_thread = new (std::nothrow) app_thread_t (this, i, flags_);
+        info.app_thread = new (std::nothrow) app_thread_t (this, i);
         zmq_assert (info.app_thread);
         app_threads.push_back (info);
         signalers.push_back (info.app_thread->get_signaler ());
@@ -62,7 +61,7 @@ zmq::dispatcher_t::dispatcher_t (int app_threads_, int io_threads_,
     //  Create I/O thread objects.
     for (int i = 0; i != io_threads_; i++) {
         io_thread_t *io_thread = new (std::nothrow) io_thread_t (this,
-            i + app_threads_, flags_);
+            i + app_threads_);
         zmq_assert (io_thread);
         io_threads.push_back (io_thread);
         signalers.push_back (io_thread->get_signaler ());
diff --git a/src/dispatcher.hpp b/src/dispatcher.hpp
index 1cd5207..6648f5d 100644
--- a/src/dispatcher.hpp
+++ b/src/dispatcher.hpp
@@ -25,7 +25,7 @@
 #include <map>
 #include <string>
 
-#include "i_signaler.hpp"
+#include "fd_signaler.hpp"
 #include "ypipe.hpp"
 #include "command.hpp"
 #include "config.hpp"
@@ -51,7 +51,7 @@ namespace zmq
         //  Create the dispatcher object. Matrix of pipes to communicate between
         //  each socket and each I/O thread is created along with appropriate
         //  signalers.
-        dispatcher_t (int app_threads_, int io_threads_, int flags_);
+        dispatcher_t (int app_threads_, int io_threads_);
 
         //  This function is called when user invokes zmq_term. If there are
         //  no more sockets open it'll cause all the infrastructure to be shut
@@ -125,7 +125,7 @@ namespace zmq
         io_threads_t io_threads;
 
         //  Signalers for both application and I/O threads.
-        std::vector <i_signaler*> signalers;
+        std::vector <fd_signaler_t*> signalers;
 
         //  Pipe to hold the commands.
         typedef ypipe_t <command_t, true,
diff --git a/src/fd_signaler.hpp b/src/fd_signaler.hpp
index f2037a9..a6ccbba 100644
--- a/src/fd_signaler.hpp
+++ b/src/fd_signaler.hpp
@@ -21,7 +21,6 @@
 #define __ZMQ_FD_SIGNALER_HPP_INCLUDED__
 
 #include "platform.hpp"
-#include "i_signaler.hpp"
 #include "fd.hpp"
 #include "stdint.hpp"
 
@@ -33,7 +32,7 @@ namespace zmq
     //  descriptor and so it can be polled on. Same signal cannot be sent twice
     //  unless signals are retrieved by the reader side in the meantime.
 
-    class fd_signaler_t : public i_signaler
+    class fd_signaler_t
     {
     public:
 
diff --git a/src/i_signaler.hpp b/src/i_signaler.hpp
deleted file mode 100644
index 822ab8e..0000000
--- a/src/i_signaler.hpp
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
-    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_I_SIGNALER_HPP_INCLUDED__
-#define __ZMQ_I_SIGNALER_HPP_INCLUDED__
-
-#include "stdint.hpp"
-#include "fd.hpp"
-
-namespace zmq
-{
-    //  Virtual interface used to send signals. Individual implementations
-    //  may restrict the number of possible signal types to send.
-
-    struct i_signaler
-    {
-        virtual ~i_signaler () {};
-
-        //  Send a signal with a specific ID.
-        virtual void signal (int signal_) = 0;
-
-        //  Wait for signal. Returns a set of signals in form of a bitmap.
-        //  Signal with index 0 corresponds to value 1, index 1 to value 2,
-        //  index 2 to value 3 etc.
-        virtual uint64_t poll () = 0;
-
-        //  Same as poll, however, if there is no signal available,
-        //  function returns zero immediately instead of waiting for a signal.
-        virtual uint64_t check () = 0;
-
-        //  Returns file descriptor that allows waiting for signals. Specific
-        //  signalers may not support this functionality. If so, the function
-        //  returns retired_fd.
-        virtual fd_t get_fd () = 0;
-    };
-
-}
-
-#endif
diff --git a/src/io_thread.cpp b/src/io_thread.cpp
index ff45478..41f7f7d 100644
--- a/src/io_thread.cpp
+++ b/src/io_thread.cpp
@@ -27,10 +27,8 @@
 #include "err.hpp"
 #include "command.hpp"
 #include "dispatcher.hpp"
-#include "simple_semaphore.hpp"
 
-zmq::io_thread_t::io_thread_t (dispatcher_t *dispatcher_, int thread_slot_,
-      int flags_) :
+zmq::io_thread_t::io_thread_t (dispatcher_t *dispatcher_, int thread_slot_) :
     object_t (dispatcher_, thread_slot_)
 {
     poller = new (std::nothrow) poller_t;
@@ -56,7 +54,7 @@ void zmq::io_thread_t::stop ()
     send_stop ();
 }
 
-zmq::i_signaler *zmq::io_thread_t::get_signaler ()
+zmq::fd_signaler_t *zmq::io_thread_t::get_signaler ()
 {
     return &signaler;
 }
diff --git a/src/io_thread.hpp b/src/io_thread.hpp
index 9377515..84b9319 100644
--- a/src/io_thread.hpp
+++ b/src/io_thread.hpp
@@ -38,8 +38,7 @@ namespace zmq
     {
     public:
 
-        io_thread_t (class dispatcher_t *dispatcher_, int thread_slot_,
-            int flags_);
+        io_thread_t (class dispatcher_t *dispatcher_, int thread_slot_);
 
         //  Clean-up. If the thread was started, it's neccessary to call 'stop'
         //  before invoking destructor. Otherwise the destructor would hang up.
@@ -52,7 +51,7 @@ namespace zmq
         void stop ();
 
         //  Returns signaler associated with this I/O thread.
-        i_signaler *get_signaler ();
+        fd_signaler_t *get_signaler ();
 
         //  i_poll_events implementation.
         void in_event ();
diff --git a/src/object.cpp b/src/object.cpp
index 9221280..113a456 100644
--- a/src/object.cpp
+++ b/src/object.cpp
@@ -24,7 +24,6 @@
 #include "err.hpp"
 #include "pipe.hpp"
 #include "io_thread.hpp"
-#include "simple_semaphore.hpp"
 #include "owned.hpp"
 #include "session.hpp"
 #include "socket_base.hpp"
diff --git a/src/queue.cpp b/src/queue.cpp
index 165e360..05cd125 100644
--- a/src/queue.cpp
+++ b/src/queue.cpp
@@ -51,8 +51,9 @@ int zmq::queue (class socket_base_t *insocket_,
         errno_assert (rc > 0);
 
         //  The algorithm below asumes ratio of request and replies processed
-        //  under full load to be 1:1. The alternative would be to process
-        //  replies first, handle request only when there are no more replies.
+        //  under full load to be 1:1. While processing requests replies first
+        //  is tempting it is suspectible to DoS attacks (overloading the system
+        //  with unsolicited replies).
 
         //  Receive a new request.
         if (items [0].revents & ZMQ_POLLIN) {
diff --git a/src/simple_semaphore.hpp b/src/simple_semaphore.hpp
deleted file mode 100644
index 78d72e5..0000000
--- a/src/simple_semaphore.hpp
+++ /dev/null
@@ -1,242 +0,0 @@
-/*
-    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_SIMPLE_SEMAPHORE_HPP_INCLUDED__
-#define __ZMQ_SIMPLE_SEMAPHORE_HPP_INCLUDED__
-
-#include "platform.hpp"
-#include "err.hpp"
-
-#if 0 //defined ZMQ_HAVE_LINUX
-#include <sys/syscall.h>
-#include <unistd.h>
-#include <linux/futex.h>
-#elif defined ZMQ_HAVE_LINUX ||defined ZMQ_HAVE_OSX || defined ZMQ_HAVE_OPENVMS
-#include <pthread.h>
-#elif defined ZMQ_HAVE_WINDOWS
-#include "windows.hpp"
-#else
-#include <semaphore.h>
-#endif
-
-namespace zmq
-{
-    //  Simple semaphore. Only single thread may be waiting at any given time.
-    //  Also, the semaphore may not be posted before the previous post
-    //  was matched by corresponding wait and the waiting thread was
-    //  released.
-
-#if 0 //defined ZMQ_HAVE_LINUX
-
-    //  In theory, using private futexes should be more efficient on Linux
-    //  platform than using mutexes. However, in uncontended cases of TCP
-    //  transport on loopback interface we haven't seen any latency improvement.
-    //  The code is commented out waiting for more thorough testing.
-
-    class simple_semaphore_t
-    { 
-    public:
-
-        //  Initialise the semaphore.
-        inline simple_semaphore_t () :
-            dummy (0)
-        {
-        }
-
-        //  Destroy the semaphore.
-        inline ~simple_semaphore_t ()
-        {
-        }
-
-        //  Wait for the semaphore.
-        inline void wait ()
-        {
-            int rc = syscall (SYS_futex, &dummy, (int) FUTEX_WAIT_PRIVATE,
-                (int) 0, NULL, NULL, (int) 0);
-            zmq_assert (rc == 0);
-        }
-
-        //  Post the semaphore.
-        inline void post ()
-        {
-            while (true) {
-                int rc = syscall (SYS_futex, &dummy, (int) FUTEX_WAKE_PRIVATE,
-                    (int) 1, NULL, NULL, (int) 0);
-                zmq_assert (rc != -1 && rc <= 1);
-                if (rc == 1)
-                    break;
-            }
-        }
-
-    private:
-
-        int dummy;
-
-        //  Disable copying of the object.
-        simple_semaphore_t (const simple_semaphore_t&);
-        void operator = (const simple_semaphore_t&);
-    };
-
-#elif defined ZMQ_HAVE_LINUX || defined ZMQ_HAVE_OSX || defined ZMQ_HAVE_OPENVMS
-
-    //  On platforms that allow for double locking of a mutex from the same
-    //  thread, simple semaphore is implemented using mutex, as it is more
-    //  efficient than full-blown semaphore.
-
-    class simple_semaphore_t
-    { 
-    public:
-
-        //  Initialise the semaphore.
-        inline simple_semaphore_t ()
-        {
-            int rc = pthread_mutex_init (&mutex, NULL);
-            posix_assert (rc);
-            rc = pthread_mutex_lock (&mutex);
-            posix_assert (rc);
-        }
-
-        //  Destroy the semaphore.
-        inline ~simple_semaphore_t ()
-        {
-            int rc = pthread_mutex_unlock (&mutex);
-            posix_assert (rc);
-            rc = pthread_mutex_destroy (&mutex);
-            posix_assert (rc);
-        }
-
-        //  Wait for the semaphore.
-        inline void wait ()
-        {
-             int rc = pthread_mutex_lock (&mutex);
-             posix_assert (rc);
-        }
-
-        //  Post the semaphore.
-        inline void post ()
-        {
-            int rc = pthread_mutex_unlock (&mutex);
-            posix_assert (rc);
-        }
-
-    private:
-
-        pthread_mutex_t mutex;
-
-        //  Disable copying of the object.
-        simple_semaphore_t (const simple_semaphore_t&);
-        void operator = (const simple_semaphore_t&);
-    };
-
-#elif defined ZMQ_HAVE_WINDOWS
-
-    //  On Windows platform simple semaphore is implemeted using event object.
-
-    class simple_semaphore_t
-    { 
-    public:
-
-        //  Initialise the semaphore.
-        inline simple_semaphore_t ()
-        {
-            ev = CreateEvent (NULL, FALSE, FALSE, NULL);
-            win_assert (ev != NULL);
-        }
-
-        //  Destroy the semaphore.
-        inline ~simple_semaphore_t ()
-        {
-            int rc = CloseHandle (ev);
-            win_assert (rc != 0);    
-        }
-
-        //  Wait for the semaphore.
-        inline void wait ()
-        {
-            DWORD rc = WaitForSingleObject (ev, INFINITE);
-            win_assert (rc != WAIT_FAILED);
-        }
-
-        //  Post the semaphore.
-        inline void post ()
-        {
-            int rc = SetEvent (ev);
-            win_assert (rc != 0);
-        }
-
-    private:
-
-        HANDLE ev;
-
-        //  Disable copying of the object.
-        simple_semaphore_t (const simple_semaphore_t&);
-        void operator = (const simple_semaphore_t&);
-    };
-
-#else
-
-    //  Default implementation maps simple semaphore to standard semaphore.
-
-    class simple_semaphore_t
-    { 
-    public:
-
-        //  Initialise the semaphore.
-        inline simple_semaphore_t ()
-        {
-             int rc = sem_init (&sem, 0, 0);
-             errno_assert (rc != -1);
-        }
-
-        //  Destroy the semaphore.
-        inline ~simple_semaphore_t ()
-        {
-             int rc = sem_destroy (&sem);
-             errno_assert (rc != -1);
-        }
-
-        //  Wait for the semaphore.
-        inline void wait ()
-        {
-             int rc = sem_wait (&sem);
-             errno_assert (rc != -1);
-        }
-
-        //  Post the semaphore.
-        inline void post ()
-        {
-            int rc = sem_post (&sem);
-            errno_assert (rc != -1);
-        }
-
-    private:
-
-        //  Underlying system semaphore object.
-        sem_t sem;
-
-        //  Disable copying of the object.
-        simple_semaphore_t (const simple_semaphore_t&);
-        void operator = (const simple_semaphore_t&);
-    };
-
-#endif
-
-}
-
-#endif
diff --git a/src/ypollset.cpp b/src/ypollset.cpp
deleted file mode 100644
index 51284a8..0000000
--- a/src/ypollset.cpp
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
-    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 "ypollset.hpp"
-
-zmq::ypollset_t::ypollset_t ()
-{
-}
-
-zmq::ypollset_t::~ypollset_t ()
-{
-}
-
-void zmq::ypollset_t::signal (int signal_)
-{
-    zmq_assert (signal_ >= 0 && signal_ < wait_signal);
-    if (bits.btsr (signal_, wait_signal))
-        sem.post (); 
-}
-
-uint64_t zmq::ypollset_t::poll ()
-{
-    signals_t result = 0;
-    while (!result) {
-        result = bits.izte (signals_t (1) << wait_signal, 0);
-        if (!result) {
-            sem.wait ();
-            result = bits.xchg (0);
-        }
-
-        //  If btsr was really atomic, result would never be 0 at this
-        //  point, i.e. no looping would be possible. However, to
-        //  support even CPU architectures without CAS instruction
-        //  we allow btsr to be composed of two independent atomic
-        //  operation (set and reset). In such case looping can occur
-        //  sporadically.
-    }
-    return (uint64_t) result;      
-}
-
-uint64_t zmq::ypollset_t::check ()
-{
-    return (uint64_t) bits.xchg (0);
-}
-
-zmq::fd_t zmq::ypollset_t::get_fd ()
-{
-    return retired_fd;
-}
diff --git a/src/ypollset.hpp b/src/ypollset.hpp
deleted file mode 100644
index c75b149..0000000
--- a/src/ypollset.hpp
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
-    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_YPOLLSET_HPP_INCLUDED__
-#define __ZMQ_YPOLLSET_HPP_INCLUDED__
-
-#include "i_signaler.hpp"
-#include "simple_semaphore.hpp"
-#include "atomic_bitmap.hpp"
-
-namespace zmq
-{
-
-    //  ypollset allows for rapid polling for up to constant number of  
-    //  different signals each produced by a different thread. The number of
-    //  possible signals is platform-dependent.
-
-    class ypollset_t : public i_signaler
-    {
-    public:
-
-        ypollset_t ();
-        ~ypollset_t ();
-
-        //  i_signaler interface implementation.
-        void signal (int signal_);
-        uint64_t poll ();
-        uint64_t check ();
-        fd_t get_fd ();
-
-    private:
-
-        //  Internal representation of signal bitmap.
-        typedef atomic_bitmap_t::bitmap_t signals_t;
-
-        //  Wait signal is carried in the most significant bit of integer.
-        enum {wait_signal = sizeof (signals_t) * 8 - 1};
-
-        //  The bits of the pollset.
-        atomic_bitmap_t bits;
-
-        //  Used by thread waiting for signals to sleep if there are no
-        //  signals available.
-        simple_semaphore_t sem;
-
-        //  Disable copying of ypollset object.
-        ypollset_t (const ypollset_t&);
-        void operator = (const ypollset_t&);
-    };
-
-}
-
-#endif
diff --git a/src/zmq.cpp b/src/zmq.cpp
index 74d52f6..c05af25 100644
--- a/src/zmq.cpp
+++ b/src/zmq.cpp
@@ -228,14 +228,7 @@ size_t zmq_msg_size (zmq_msg_t *msg_)
 
 void *zmq_init (int app_threads_, int io_threads_, int flags_)
 {
-    //  There should be at least a single application thread managed
-    //  by the dispatcher. There's no need for I/O threads if 0MQ is used
-    //  only for inproc messaging
-    if (app_threads_ < 1 || io_threads_ < 0 ||
-          app_threads_ > 63 || io_threads_ > 63) {
-        errno = EINVAL;
-        return NULL;
-    }
+    //  There are no context flags defined at the moment, so flags_ is ignored.
 
 #if defined ZMQ_HAVE_OPENPGM
     //  Unfortunately, OpenPGM doesn't support refcounted init/shutdown, thus,
@@ -269,7 +262,7 @@ void *zmq_init (int app_threads_, int io_threads_, int flags_)
 
     //  Create 0MQ context.
     zmq::dispatcher_t *dispatcher = new (std::nothrow) zmq::dispatcher_t (
-        app_threads_, io_threads_, flags_);
+        app_threads_, io_threads_);
     zmq_assert (dispatcher);
     return (void*) dispatcher;
 }