Add support for main loop integration

This adds two new functions:

void
cogl_poll_get_info (CoglContext *context,
                    CoglPollFD **poll_fds,
                    int *n_poll_fds,
                    gint64 *timeout);

void
cogl_poll_dispatch (CoglContext *context,
                    const CoglPollFD *poll_fds,
                    int n_poll_fds);

The application is expected to call the first function whenever it is
about to block to go idle, and the second function whenever it comes
out of idle. This gives Cogl winsys's the ability poll file
descriptors for events. For example when handing swap complete
notifications, it can report that it needs to block on a file
descriptor.

The two functions are backed by winsys virtual functions. There are
currently no implementations. The default handler for get_info just
reports no file descriptors and an infinite timeout.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

cogl/Makefile.am

@@ -73,6 +73,7 @@ cogl_public_h = \
 	$(srcdir)/cogl-primitives.h 		\
 	$(srcdir)/cogl-path.h 			\
 	$(srcdir)/cogl-pixel-buffer.h		\
+	$(srcdir)/cogl-poll.h			\
 	$(srcdir)/cogl-shader.h 		\
 	$(srcdir)/cogl-texture.h 		\
 	$(srcdir)/cogl-texture-3d.h             \
@@ -335,6 +336,7 @@ cogl_sources_c = \
 	$(srcdir)/cogl-boxed-value.c			\
 	$(srcdir)/cogl-snippet-private.h		\
 	$(srcdir)/cogl-snippet.c			\
+	$(srcdir)/cogl-poll.c				\
 	$(srcdir)/gl-prototypes/cogl-all-functions.h	\
 	$(srcdir)/gl-prototypes/cogl-gles1-functions.h	\
 	$(srcdir)/gl-prototypes/cogl-gles2-functions.h	\

cogl/cogl-poll.c

@@ -0,0 +1,77 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2012 Intel Corporation.
+ *
+ * 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 License, 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, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Authors:
+ *  Neil Roberts <neil@linux.intel.com>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "cogl-poll.h"
+#include "cogl-winsys-private.h"
+#include "cogl-context-private.h"
+
+void
+cogl_poll_get_info (CoglContext *context,
+                    CoglPollFD **poll_fds,
+                    int *n_poll_fds,
+                    gint64 *timeout)
+{
+  const CoglWinsysVtable *winsys;
+
+  _COGL_RETURN_IF_FAIL (cogl_is_context (context));
+  _COGL_RETURN_IF_FAIL (poll_fds != NULL);
+  _COGL_RETURN_IF_FAIL (n_poll_fds != NULL);
+  _COGL_RETURN_IF_FAIL (timeout != NULL);
+
+  winsys = _cogl_context_get_winsys (context);
+
+  if (winsys->poll_get_info)
+    {
+      winsys->poll_get_info (context,
+                             poll_fds,
+                             n_poll_fds,
+                             timeout);
+      return;
+    }
+
+  /* By default we'll assume Cogl doesn't need to block on anything */
+  *poll_fds = NULL;
+  *n_poll_fds = 0;
+  *timeout = -1; /* no timeout */
+}
+
+void
+cogl_poll_dispatch (CoglContext *context,
+                    const CoglPollFD *poll_fds,
+                    int n_poll_fds)
+{
+  const CoglWinsysVtable *winsys;
+
+  _COGL_RETURN_IF_FAIL (cogl_is_context (context));
+
+  winsys = _cogl_context_get_winsys (context);
+
+  if (winsys->poll_dispatch)
+    winsys->poll_dispatch (context, poll_fds, n_poll_fds);
+}

cogl/cogl-poll.h

@@ -0,0 +1,166 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2012 Intel Corporation.
+ *
+ * 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 License, 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Authors:
+ *  Neil Roberts <neil@linux.intel.com>
+ */
+
+#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <cogl/cogl.h> can be included directly."
+#endif
+
+#ifndef __COGL_POLL_H__
+#define __COGL_POLL_H__
+
+#include <glib.h>
+#include <cogl/cogl-defines.h>
+#include <cogl/cogl-context.h>
+
+G_BEGIN_DECLS
+
+/**
+ * SECTION:cogl-poll
+ * @short_description: Functions for integrating Cogl with an
+ *   application's main loop
+ *
+ * Cogl needs to integrate with the application's main loop so that it
+ * can internally handle some events from the driver. All Cogl
+ * applications must use these functions. They provide enough
+ * information to describe the state that Cogl will need to wake up
+ * on. An application using the GLib main loop can instead use
+ * cogl_glib_source_new() which provides a #GSource ready to be added
+ * to the main loop.
+ */
+
+/**
+ * CoglPollFDEvent:
+ *
+ * A bitmask of events that Cogl may need to wake on for a file
+ * descriptor. Note that these all have the same values as the
+ * corresponding defines for the poll function call on Unix so they
+ * may be directly passed to poll.
+ *
+ * Since: 1.10
+ * Stability: unstable
+ */
+typedef enum
+{
+  COGL_POLL_FD_EVENT_IN = COGL_SYSDEF_POLLIN,
+  COGL_POLL_FD_EVENT_PRI = COGL_SYSDEF_POLLPRI,
+  COGL_POLL_FD_EVENT_OUT = COGL_SYSDEF_POLLOUT,
+  COGL_POLL_FD_EVENT_ERR = COGL_SYSDEF_POLLERR,
+  COGL_POLL_FD_EVENT_HUP = COGL_SYSDEF_POLLHUP,
+  COGL_POLL_FD_EVENT_NVAL = COGL_SYSDEF_POLLNVAL
+} CoglPollFDEvent;
+
+/**
+ * CoglPollFD:
+ * @fd: The file descriptor to block on
+ * @events: A bitmask of events to block on
+ * @revents: A bitmask of returned events
+ *
+ * A struct for describing the state of a file descriptor that Cogl
+ * needs to block on. The @events field contains a bitmask of
+ * #CoglPollFDEvent<!-- -->s that should cause the application to wake
+ * up. After the application is woken up from idle it should pass back
+ * an array of #CoglPollFD<!-- -->s to Cogl and update the @revents
+ * mask to the actual events that occurred on the file descriptor.
+ *
+ * Note that CoglPollFD is deliberately exactly the same as struct
+ * pollfd on Unix so that it can simply be cast when calling poll.
+ *
+ * Since: 1.10
+ * Stability: unstable
+ */
+typedef struct {
+  int fd;
+  short int events;
+  short int revents;
+} CoglPollFD;
+
+/**
+ * cogl_poll_get_info:
+ * @context: A #CoglContext
+ * @poll_fds: A return location for a pointer to an array
+ *            of #CoglPollFD<!-- -->s
+ * @n_poll_fds: A return location for the number of entries in *@poll_fds
+ * @timeout: A return location for the maximum length of time to wait
+ *           in microseconds, or -1 to wait indefinitely.
+ *
+ * This should be called whenever an application is about to go idle
+ * so that Cogl has a chance to describe what state it needs to be
+ * woken up on. The assumption is that the application is using a main
+ * loop with something like the poll function call on Unix or the GLib
+ * main loop.
+ *
+ * After the function is called *@poll_fds will contain a pointer to
+ * an array of #CoglPollFD structs describing the file descriptors
+ * that Cogl expects. The fd and events members will be updated
+ * accordingly. After the application has completed its idle it is
+ * expected to either update the revents members directly in this
+ * array or to create a copy of the array and update them
+ * there. Either way it should pass a pointer to either array back to
+ * Cogl when calling cogl_poll_dispatch().
+ *
+ * When using the %COGL_WINSYS_ID_WGL winsys (where file descriptors
+ * don't make any sense) or %COGL_WINSYS_ID_SDL (where the event
+ * handling functions of SDL don't allow blocking on a file
+ * descriptor) *n_poll_fds is guaranteed to be zero.
+ *
+ * @timeout will contain a maximum amount of time to wait in
+ * microseconds before the application should wake up or -1 if the
+ * application should wait indefinitely. This can also be 0 zero if
+ * Cogl needs to be woken up immediately.
+ *
+ * Stability: unstable
+ * Since: 1.10
+ */
+void
+cogl_poll_get_info (CoglContext *context,
+                    CoglPollFD **poll_fds,
+                    int *n_poll_fds,
+                    gint64 *timeout);
+
+/**
+ * cogl_poll_dispatch:
+ * @context: A #CoglContext
+ * @poll_fds: An array of #CoglPollFD<!-- -->s describing the events
+ *            that have occurred since the application went idle.
+ * @n_poll_fds: The length of the @poll_fds array.
+ *
+ * This should be called whenever an application is woken up from
+ * going idle in its main loop. The @poll_fds array should contain a
+ * list of file descriptors matched with the events that occurred in
+ * revents. The events field is ignored. It is safe to pass in extra
+ * file descriptors that Cogl didn't request from
+ * cogl_context_begin_idle() or a shorter array missing some file
+ * descriptors that Cogl requested.
+ *
+ * Stability: unstable
+ * Since: 1.10
+ */
+void
+cogl_poll_dispatch (CoglContext *context,
+                    const CoglPollFD *poll_fds,
+                    int n_poll_fds);
+
+#endif /* __COGL_POLL_H__ */

cogl/cogl.h

@@ -97,6 +97,7 @@ typedef struct _CoglFramebuffer CoglFramebuffer;
 #include <cogl/cogl-snippet.h>
 #include <cogl/cogl-framebuffer.h>
 #include <cogl/cogl-onscreen.h>
+#include <cogl/cogl-poll.h>
 #if defined (COGL_HAS_EGL_PLATFORM_WAYLAND_SUPPORT)
 #include <cogl/cogl-wayland-renderer.h>
 #endif

cogl/winsys/cogl-winsys-private.h

@@ -151,6 +151,16 @@ typedef struct _CoglWinsysVtable
   (*onscreen_remove_swap_buffers_callback) (CoglOnscreen *onscreen,
                                             unsigned int id);
 
+  void
+  (*poll_get_info) (CoglContext *context,
+                    CoglPollFD **poll_fds,
+                    int *n_poll_fds,
+                    gint64 *timeout);
+  void
+  (*poll_dispatch) (CoglContext *context,
+                    const CoglPollFD *poll_fds,
+                    int n_poll_fds);
+
 #ifdef COGL_HAS_XLIB_SUPPORT
   gboolean
   (*texture_pixmap_x11_create) (CoglTexturePixmapX11 *tex_pixmap);

configure.ac

@@ -1023,10 +1023,48 @@ dnl The 'ffs' function is part of C99 so it isn't always
 dnl available. Cogl has a fallback if needed.
 AC_CHECK_FUNCS([ffs])
 
+dnl ================================================================
+dnl Platform values
+dnl ================================================================
+
+dnl These are values from system headers that we want to copy into the
+dnl public Cogl headers without having to include the system header
+AC_CHECK_HEADER(poll.h,
+        [
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLIN, POLLIN, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLIN]))
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLPRI, POLLPRI, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLPRI]))
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLOUT, POLLOUT, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLOUT]))
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLERR, POLLERR, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLERR]))
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLHUP, POLLHUP, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLHUP]))
+         AC_COMPUTE_INT(COGL_SYSDEF_POLLNVAL, POLLNVAL, [#include <poll.h>],
+                        AC_MSG_ERROR([Unable to get value of POLLNVAL]))
+        ],
+        [
+         COGL_SYSDEF_POLLIN=1
+         COGL_SYSDEF_POLLPRI=2
+         COGL_SYSDEF_POLLOUT=4
+         COGL_SYSDEF_POLLERR=8
+         COGL_SYSDEF_POLLHUP=16
+         COGL_SYSDEF_POLLNVAL=32
+        ])
+COGL_DEFINES_EXTRA="$COGL_DEFINES_EXTRA
+#define COGL_SYSDEF_POLLIN $COGL_SYSDEF_POLLIN
+#define COGL_SYSDEF_POLLPRI $COGL_SYSDEF_POLLPRI
+#define COGL_SYSDEF_POLLOUT $COGL_SYSDEF_POLLOUT
+#define COGL_SYSDEF_POLLERR $COGL_SYSDEF_POLLERR
+#define COGL_SYSDEF_POLLHUP $COGL_SYSDEF_POLLHUP
+#define COGL_SYSDEF_POLLNVAL $COGL_SYSDEF_POLLNVAL
+"
+
 dnl ================================================================
 dnl What needs to be substituted in other files
 dnl ================================================================
-COGL_DEFINES=""
+COGL_DEFINES="$COGL_DEFINES_EXTRA"
 for x in $COGL_DEFINES_SYMBOLS; do
   COGL_DEFINES="$COGL_DEFINES
 #define $x 1"

doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-docs.xml.in

@@ -62,6 +62,7 @@
 
     <xi:include href="xml/cogl-object.xml"/>
     <xi:include href="xml/cogl-context.xml"/>
+    <xi:include href="xml/cogl-poll.xml"/>
 
     <section id="cogl-pipeline-apis">
       <title>Setting Up A GPU Pipeline</title>

doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-sections.txt

@@ -167,6 +167,15 @@ COGL_UNORDERED_MASK
 COGL_UNPREMULT_MASK
 </SECTION>
 
+<SECTION>
+<FILE>cogl-poll</FILE>
+<TITLE>Main loop integeration</TITLE>
+CoglPollFDEvent
+CoglPollFD
+cogl_poll_get_info
+cogl_poll_dispatch
+</SECTION>
+
 <SECTION>
 <FILE>cogl-clipping</FILE>
 <TITLE>Clipping</TITLE>