1 files changed, 260 insertions, 0 deletions
diff --git a/glib/glib/gwakeup.c b/glib/glib/gwakeup.c
new file mode 100644
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--- /dev/null
+++ b/glib/glib/gwakeup.c
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+/*
+ * Copyright © 2011 Canonical Limited
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Ryan Lortie <desrt@desrt.ca>
+ */
+
+#include "config.h"
+
+
+/* gwakeup.h is special -- GIO and some test cases include it.  As such,
+ * it cannot include other glib headers without triggering the single
+ * includes warnings.  We have to manually include its dependencies here
+ * (and at all other use sites).
+ */
+#ifdef GLIB_COMPILATION
+#include "gtypes.h"
+#include "gpoll.h"
+#else
+#include <glib.h>
+#endif
+
+#include "gwakeup.h"
+
+/*< private >
+ * SECTION:gwakeup
+ * @title: GWakeup
+ * @short_description: portable cross-thread event signal mechanism
+ *
+ * #GWakeup is a simple and portable way of signaling events between
+ * different threads in a way that integrates nicely with g_poll().
+ * GLib uses it internally for cross-thread signalling in the
+ * implementation of #GMainContext and #GCancellable.
+ *
+ * You first create a #GWakeup with g_wakeup_new() and initialise a
+ * #GPollFD from it using g_wakeup_get_pollfd().  Polling on the created
+ * #GPollFD will block until g_wakeup_signal() is called, at which point
+ * it will immediately return.  Future attempts to poll will continue to
+ * return until g_wakeup_acknowledge() is called.  g_wakeup_free() is
+ * used to free a #GWakeup.
+ *
+ * On sufficiently modern Linux, this is implemented using eventfd.  On
+ * Windows it is implemented using an event handle.  On other systems it
+ * is implemented with a pair of pipes.
+ *
+ * Since: 2.30
+ **/
+#ifdef _WIN32
+
+#include <windows.h>
+
+#ifdef GLIB_COMPILATION
+#include "gmessages.h"
+#include "giochannel.h"
+#include "gwin32.h"
+#endif
+
+GWakeup *
+g_wakeup_new (void)
+{
+  HANDLE wakeup;
+
+  wakeup = CreateEvent (NULL, TRUE, FALSE, NULL);
+
+  if (wakeup == NULL)
+    g_error ("Cannot create event for GWakeup: %s",
+             g_win32_error_message (GetLastError ()));
+
+  return (GWakeup *) wakeup;
+}
+
+void
+g_wakeup_get_pollfd (GWakeup *wakeup,
+                     GPollFD *poll_fd)
+{
+  poll_fd->fd = (gintptr) wakeup;
+  poll_fd->events = G_IO_IN;
+}
+
+void
+g_wakeup_acknowledge (GWakeup *wakeup)
+{
+  ResetEvent ((HANDLE) wakeup);
+}
+
+void
+g_wakeup_signal (GWakeup *wakeup)
+{
+  SetEvent ((HANDLE) wakeup);
+}
+
+void
+g_wakeup_free (GWakeup *wakeup)
+{
+  CloseHandle ((HANDLE) wakeup);
+}
+
+#else
+
+#include "glib-unix.h"
+#include <fcntl.h>
+
+#if defined (HAVE_EVENTFD)
+#include <sys/eventfd.h>
+#endif
+
+struct _GWakeup
+{
+  gint fds[2];
+};
+
+/**
+ * g_wakeup_new:
+ *
+ * Creates a new #GWakeup.
+ *
+ * You should use g_wakeup_free() to free it when you are done.
+ *
+ * Returns: a new #GWakeup
+ *
+ * Since: 2.30
+ **/
+GWakeup *
+g_wakeup_new (void)
+{
+  GError *error = NULL;
+  GWakeup *wakeup;
+
+  wakeup = g_slice_new (GWakeup);
+
+  /* try eventfd first, if we think we can */
+#if defined (HAVE_EVENTFD)
+#ifndef TEST_EVENTFD_FALLBACK
+  wakeup->fds[0] = eventfd (0, EFD_CLOEXEC | EFD_NONBLOCK);
+#else
+  wakeup->fds[0] = -1;
+#endif
+
+  if (wakeup->fds[0] != -1)
+    {
+      wakeup->fds[1] = -1;
+      return wakeup;
+    }
+
+  /* for any failure, try a pipe instead */
+#endif
+
+  if (!g_unix_open_pipe (wakeup->fds, FD_CLOEXEC, &error))
+    g_error ("Creating pipes for GWakeup: %s\n", error->message);
+
+  if (!g_unix_set_fd_nonblocking (wakeup->fds[0], TRUE, &error) ||
+      !g_unix_set_fd_nonblocking (wakeup->fds[1], TRUE, &error))
+    g_error ("Set pipes non-blocking for GWakeup: %s\n", error->message);
+
+  return wakeup;
+}
+
+/**
+ * g_wakeup_get_pollfd:
+ * @wakeup: a #GWakeup
+ * @poll_fd: a #GPollFD
+ *
+ * Prepares a @poll_fd such that polling on it will succeed when
+ * g_wakeup_signal() has been called on @wakeup.
+ *
+ * @poll_fd is valid until @wakeup is freed.
+ *
+ * Since: 2.30
+ **/
+void
+g_wakeup_get_pollfd (GWakeup *wakeup,
+                     GPollFD *poll_fd)
+{
+  poll_fd->fd = wakeup->fds[0];
+  poll_fd->events = G_IO_IN;
+}
+
+/**
+ * g_wakeup_acknowledge:
+ * @wakeup: a #GWakeup
+ *
+ * Acknowledges receipt of a wakeup signal on @wakeup.
+ *
+ * You must call this after @wakeup polls as ready.  If not, it will
+ * continue to poll as ready until you do so.
+ *
+ * If you call this function and @wakeup is not signaled, nothing
+ * happens.
+ *
+ * Since: 2.30
+ **/
+void
+g_wakeup_acknowledge (GWakeup *wakeup)
+{
+  char buffer[16];
+
+  /* read until it is empty */
+  while (read (wakeup->fds[0], buffer, sizeof buffer) == sizeof buffer);
+}
+
+/**
+ * g_wakeup_signal:
+ * @wakeup: a #GWakeup
+ *
+ * Signals @wakeup.
+ *
+ * Any future (or present) polling on the #GPollFD returned by
+ * g_wakeup_get_pollfd() will immediately succeed until such a time as
+ * g_wakeup_acknowledge() is called.
+ *
+ * This function is safe to call from a UNIX signal handler.
+ *
+ * Since: 2.30
+ **/
+void
+g_wakeup_signal (GWakeup *wakeup)
+{
+  guint64 one = 1;
+
+  if (wakeup->fds[1] == -1)
+    write (wakeup->fds[0], &one, sizeof one);
+  else
+    write (wakeup->fds[1], &one, 1);
+}
+
+/**
+ * g_wakeup_free:
+ * @wakeup: a #GWakeup
+ *
+ * Frees @wakeup.
+ *
+ * You must not currently be polling on the #GPollFD returned by
+ * g_wakeup_get_pollfd(), or the result is undefined.
+ **/
+void
+g_wakeup_free (GWakeup *wakeup)
+{
+  close (wakeup->fds[0]);
+
+  if (wakeup->fds[1] != -1)
+    close (wakeup->fds[1]);
+
+  g_slice_free (GWakeup, wakeup);
+}
+
+#endif /* !_WIN32 */