/* Function for handling the GLib event loop.
-Copyright (C) 2009-2014 Free Software Foundation, Inc.
+Copyright (C) 2009-2015 Free Software Foundation, Inc.
This file is part of GNU Emacs.
#include <stdbool.h>
#include <timespec.h>
#include "frame.h"
+#include "blockinput.h"
+
+/* `xg_select' is a `pselect' replacement. Why do we need a separate function?
+ 1. Timeouts. Glib and Gtk rely on timer events. If we did pselect
+ with a greater timeout then the one scheduled by Glib, we would
+ not allow Glib to process its timer events. We want Glib to
+ work smoothly, so we need to reduce our timeout to match Glib.
+ 2. Descriptors. Glib may listen to more file descriptors than we do.
+ So we add Glib descriptors to our pselect pool, but we don't change
+ the value returned by the function. The return value matches only
+ the descriptors passed as arguments, making it compatible with
+ plain pselect. */
int
xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds,
int have_wfds = wfds != NULL;
GPollFD gfds_buf[128];
GPollFD *gfds = gfds_buf;
- int gfds_size = sizeof gfds_buf / sizeof *gfds_buf;
+ int gfds_size = ARRAYELTS (gfds_buf);
int n_gfds, retval = 0, our_fds = 0, max_fds = fds_lim - 1;
+ bool context_acquired = false;
int i, nfds, tmo_in_millisec;
bool need_to_dispatch;
USE_SAFE_ALLOCA;
- /* Do not try to optimize with an initial check with g_main_context_pending
- and a call to pselect if it returns false. If Gdk has a timeout for 0.01
- second, and Emacs has a timeout for 1 second, g_main_context_pending will
- return false, but the timeout will be 1 second, thus missing the gdk
- timeout with a lot. */
-
context = g_main_context_default ();
+ context_acquired = g_main_context_acquire (context);
+ /* FIXME: If we couldn't acquire the context, we just silently proceed
+ because this function handles more than just glib file descriptors.
+ Note that, as implemented, this failure is completely silent: there is
+ no feedback to the caller. */
if (rfds) all_rfds = *rfds;
else FD_ZERO (&all_rfds);
if (wfds) all_wfds = *wfds;
else FD_ZERO (&all_wfds);
- n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
- gfds, gfds_size);
+ n_gfds = (context_acquired
+ ? g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
+ gfds, gfds_size)
+ : -1);
+
if (gfds_size < n_gfds)
{
SAFE_NALLOCA (gfds, sizeof *gfds, n_gfds);
SAFE_FREE ();
- if (tmo_in_millisec >= 0)
+ if (n_gfds >= 0 && tmo_in_millisec >= 0)
{
tmo = make_timespec (tmo_in_millisec / 1000,
1000 * 1000 * (tmo_in_millisec % 1000));
if (need_to_dispatch)
{
int pselect_errno = errno;
+ /* Prevent g_main_dispatch recursion, that would occur without
+ block_input wrapper, because event handlers call
+ unblock_input. Event loop recursion was causing Bug#15801. */
+ block_input ();
while (g_main_context_pending (context))
- g_main_context_dispatch (context);
+ g_main_context_dispatch (context);
+ unblock_input ();
errno = pselect_errno;
}
+ if (context_acquired)
+ g_main_context_release (context);
+
/* To not have to recalculate timeout, return like this. */
if ((our_fds > 0 || (nfds == 0 && tmop == &tmo)) && (retval == 0))
{