Get maximum number of sockets it can handle from poller_t

src/ctx.cpp

@@ -38,6 +38,14 @@
 #define ZMQ_CTX_TAG_VALUE_GOOD 0xabadcafe
 #define ZMQ_CTX_TAG_VALUE_BAD  0xdeadbeef
 
+int clipped_maxsocket(int max_requested)
+{
+    if (max_requested >= zmq::poller_t::max_fds() && zmq::poller_t::max_fds() != -1)
+        max_requested = zmq::poller_t::max_fds() - 1;		// -1 because we need room for the repear mailbox.
+    
+    return max_requested;
+}
+
 zmq::ctx_t::ctx_t () :
     tag (ZMQ_CTX_TAG_VALUE_GOOD),
     starting (true),
@@ -45,7 +53,7 @@ zmq::ctx_t::ctx_t () :
     reaper (NULL),
     slot_count (0),
     slots (NULL),
-    max_sockets (ZMQ_MAX_SOCKETS_DFLT),
+    max_sockets(clipped_maxsocket(ZMQ_MAX_SOCKETS_DFLT)),
     io_thread_count (ZMQ_IO_THREADS_DFLT),
     ipv6 (false)
 {
@@ -161,7 +169,7 @@ int zmq::ctx_t::shutdown ()
 int zmq::ctx_t::set (int option_, int optval_)
 {
     int rc = 0;
-    if (option_ == ZMQ_MAX_SOCKETS && optval_ >= 1) {
+    if (option_ == ZMQ_MAX_SOCKETS && optval_ >= 1 && optval_ == clipped_maxsocket(optval_)) {
         opt_sync.lock ();
         max_sockets = optval_;
         opt_sync.unlock ();

src/devpoll.cpp

@@ -133,6 +133,11 @@ void zmq::devpoll_t::stop ()
     stopping = true;
 }
 
+int zmq::devpoll_t::max_fds()
+{
+    return -1;
+}
+
 void zmq::devpoll_t::loop ()
 {
     while (!stopping) {

src/devpoll.hpp

@@ -56,6 +56,8 @@ namespace zmq
         void start ();
         void stop ();
 
+        static int max_fds();
+
     private:
 
         //  Main worker thread routine.

src/epoll.cpp

@@ -126,6 +126,11 @@ void zmq::epoll_t::stop ()
     stopping = true;
 }
 
+int zmq::epoll_t::max_fds()
+{
+    return -1;
+}
+
 void zmq::epoll_t::loop ()
 {
     epoll_event ev_buf [max_io_events];

src/epoll.hpp

@@ -58,6 +58,8 @@ namespace zmq
         void start ();
         void stop ();
 
+        static int max_fds();
+
     private:
 
         //  Main worker thread routine.

src/kqueue.cpp

@@ -152,6 +152,11 @@ void zmq::kqueue_t::stop ()
     stopping = true;
 }
 
+int zmq::kqueue_t::max_fds()
+{
+    return -1;
+}
+
 void zmq::kqueue_t::loop ()
 {
     while (!stopping) {

src/kqueue.hpp

@@ -58,6 +58,8 @@ namespace zmq
         void start ();
         void stop ();
 
+        static int max_fds();
+
     private:
 
         //  Main worker thread routine.

src/poll.cpp

@@ -114,6 +114,11 @@ void zmq::poll_t::stop ()
     stopping = true;
 }
 
+int zmq::poll_t::max_fds()
+{
+    return -1;
+}
+
 void zmq::poll_t::loop ()
 {
     while (!stopping) {

src/poll.hpp

@@ -59,6 +59,8 @@ namespace zmq
         void start ();
         void stop ();
 
+        static int max_fds();
+
     private:
 
         //  Main worker thread routine.

src/select.cpp

@@ -144,6 +144,11 @@ void zmq::select_t::stop ()
     stopping = true;
 }
 
+int zmq::select_t::max_fds()
+{
+    return FD_SETSIZE;
+}
+
 void zmq::select_t::loop ()
 {
     while (!stopping) {

src/select.hpp

@@ -69,6 +69,8 @@ namespace zmq
         void start ();
         void stop ();
 
+        static int max_fds();
+
     private:
 
         //  Main worker thread routine.