Merge commit 'e988fee1679536137b87d10e939eff5c1f27c8ab' as 'libs/libzmq'

libs/libzmq/src/signaler.hpp

@@ -0,0 +1,88 @@
+/*
+    Copyright (c) 2007-2016 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_SIGNALER_HPP_INCLUDED__
+#define __ZMQ_SIGNALER_HPP_INCLUDED__
+
+#ifdef HAVE_FORK
+#include <unistd.h>
+#endif
+
+#include "fd.hpp"
+#include "macros.hpp"
+
+namespace zmq
+{
+//  This is a cross-platform equivalent to signal_fd. However, as opposed
+//  to signal_fd there can be at most one signal in the signaler at any
+//  given moment. Attempt to send a signal before receiving the previous
+//  one will result in undefined behaviour.
+
+class signaler_t
+{
+  public:
+    signaler_t ();
+    ~signaler_t ();
+
+    // Returns the socket/file descriptor
+    // May return retired_fd if the signaler could not be initialized.
+    fd_t get_fd () const;
+    void send ();
+    int wait (int timeout_) const;
+    void recv ();
+    int recv_failable ();
+
+    bool valid () const;
+
+#ifdef HAVE_FORK
+    // close the file descriptors in a forked child process so that they
+    // do not interfere with the context in the parent process.
+    void forked ();
+#endif
+
+  private:
+    //  Underlying write & read file descriptor
+    //  Will be -1 if an error occurred during initialization, e.g. we
+    //  exceeded the number of available handles
+    fd_t _w;
+    fd_t _r;
+
+#ifdef HAVE_FORK
+    // the process that created this context. Used to detect forking.
+    pid_t pid;
+    // idempotent close of file descriptors that is safe to use by destructor
+    // and forked().
+    void close_internal ();
+#endif
+
+    ZMQ_NON_COPYABLE_NOR_MOVABLE (signaler_t)
+};
+}
+
+#endif