Problem: polling utilities not at a reusable location

Solution: move to separate header

src/polling_util.hpp

@@ -0,0 +1,122 @@
+/*
+    Copyright (c) 2007-2018 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq 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 GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_SOCKET_POLLING_UTIL_HPP_INCLUDED__
+#define __ZMQ_SOCKET_POLLING_UTIL_HPP_INCLUDED__
+
+#include <stdlib.h>
+
+#include "stdint.hpp"
+#include "platform.hpp"
+#include "err.hpp"
+
+namespace zmq
+{
+template <typename T, size_t S> class fast_vector_t
+{
+  public:
+    explicit fast_vector_t (const size_t nitems_)
+    {
+        if (nitems_ > S) {
+            _buf = static_cast<T *> (malloc (nitems_ * sizeof (T)));
+            //  TODO since this function is called by a client, we could return errno == ENOMEM here
+            alloc_assert (_buf);
+        } else {
+            _buf = _static_buf;
+        }
+    }
+
+    T &operator[] (const size_t i) { return _buf[i]; }
+
+    ~fast_vector_t ()
+    {
+        if (_buf != _static_buf)
+            free (_buf);
+    }
+
+  private:
+    fast_vector_t (const fast_vector_t &);
+    fast_vector_t &operator= (const fast_vector_t &);
+
+    T _static_buf[S];
+    T *_buf;
+};
+
+#if defined ZMQ_POLL_BASED_ON_POLL
+typedef int timeout_t;
+
+timeout_t compute_timeout (const bool first_pass_,
+                           const long timeout_,
+                           const uint64_t now_,
+                           const uint64_t end_);
+
+#elif defined ZMQ_POLL_BASED_ON_SELECT
+inline size_t valid_pollset_bytes (const fd_set &pollset_)
+{
+#if defined ZMQ_HAVE_WINDOWS
+    // On Windows we don't need to copy the whole fd_set.
+    // SOCKETS are continuous from the beginning of fd_array in fd_set.
+    // We just need to copy fd_count elements of fd_array.
+    // We gain huge memcpy() improvement if number of used SOCKETs is much lower than FD_SETSIZE.
+    return reinterpret_cast<const char *> (
+             &pollset_.fd_array[pollset_.fd_count])
+           - reinterpret_cast<const char *> (&pollset_);
+#else
+    return sizeof (fd_set);
+#endif
+}
+
+#if defined ZMQ_HAVE_WINDOWS
+class optimized_fd_set_t
+{
+  public:
+    explicit optimized_fd_set_t (size_t nevents_) : _fd_set (nevents_) {}
+
+    fd_set *get () { return reinterpret_cast<fd_set *> (&_fd_set[0]); }
+
+  private:
+    fast_vector_t<char, sizeof (u_int) + ZMQ_POLLITEMS_DFLT * sizeof (SOCKET)>
+      _fd_set;
+};
+#else
+class optimized_fd_set_t
+{
+  public:
+    explicit optimized_fd_set_t (size_t /*nevents_*/) {}
+
+    fd_set *get () { return &_fd_set; }
+
+  private:
+    fd_set _fd_set;
+};
+#endif
+#endif
+}
+
+#endif