128 lines
4.6 KiB
Diff
128 lines
4.6 KiB
Diff
From 5d0dfb203a4945eff28ad1696647b19dd0ef10e5 Mon Sep 17 00:00:00 2001
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From: Kristian Rietveld <kris@lanedo.com>
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Date: Mon, 8 Jul 2013 12:04:04 +0200
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Subject: [PATCH 67/68] quartz: Make event loop deal with recursive poll
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invocations
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This patch addresses a number of problems with the recursion in
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poll_func() that happens on OS X. Firstly, autorelease pool refreshes
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are done from prepare and only if we are at the base level of *both*
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main loops and not recursing in poll. This first part incorporates
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suggestions from Daniel Sabo and John Ralls.
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Secondly, a mechanism is implemented to detect if poll has been
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called recursively. This is used to discard file descriptor state
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at the base level, retrieved before possibly recursing (through the
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NSApp get next event).
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---
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gdk/quartz/gdkeventloop-quartz.c | 106 ++++++++++++++++++++++++++++----------
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1 file changed, 78 insertions(+), 28 deletions(-)
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diff --git a/gdk/quartz/gdkeventloop-quartz.c b/gdk/quartz/gdkeventloop-quartz.c
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index 224d84c..36c716a 100644
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--- a/gdk/quartz/gdkeventloop-quartz.c
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+++ b/gdk/quartz/gdkeventloop-quartz.c
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@@ -168,6 +168,12 @@ static pthread_cond_t select_thread_cond = PTHREAD_COND_INITIALIZER;
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static GPollFD *current_pollfds;
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static guint current_n_pollfds;
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+/* We maintain serial numbers for calls to the start function. Because we
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+ * only test for equality of this number (and not smaller/greater than)
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+ * no special handling is needed for wrap around.
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+ */
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+static guint select_thread_start_serial = 0;
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+
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/* These are the file descriptors that the select thread should pick
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* up and start polling when it has a chance.
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*/
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@@ -399,6 +405,8 @@ select_thread_start_poll (GPollFD *ufds,
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gint poll_fd_index = -1;
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gint i;
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+ select_thread_start_serial++;
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+
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for (i = 0; i < nfds; i++)
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if (ufds[i].fd == -1)
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{
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@@ -703,15 +721,33 @@ poll_func (GPollFD *ufds,
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NSEvent *event;
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NSDate *limit_date;
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gint n_ready;
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+ guint current_select_thread_serial;
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- static GPollFD *last_ufds;
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+ /* Maintain current poll parameters as static parameters. On recursive
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+ * calls to poll, we update the values. This way, if the poll array
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+ * is updated in an recursive call, we can still access the new array
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+ * when the recursion is wound down.
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+ *
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+ * The ufds value that is pushed in is allocated in g_main_context_iterate()
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+ * and is only reallocated for enlargement of this array. The array thus
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+ * never shrinks.
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+ */
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+ static GPollFD *current_ufds = NULL;
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+ static int current_nfds = 0;
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- last_ufds = ufds;
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+ current_ufds = ufds;
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+ current_nfds = nfds;
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n_ready = select_thread_start_poll (ufds, nfds, timeout_);
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if (n_ready > 0)
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timeout_ = 0;
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+ /* Using this serial number, we can check below whether the select
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+ * thread was started/collected in a recursive invocation of this
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+ * function.
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+ */
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+ current_select_thread_serial = select_thread_start_serial;
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+
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if (timeout_ == -1)
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limit_date = [NSDate distantFuture];
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else if (timeout_ == 0)
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@@ -726,17 +762,31 @@ poll_func (GPollFD *ufds,
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dequeue: YES];
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getting_events--;
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- /* We check if last_ufds did not change since the time this function was
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- * called. It is possible that a recursive main loop (and thus recursive
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- * invocation of this poll function) is triggered while in
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- * nextEventMatchingMask:. If during that time new fds are added,
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- * the cached fds array might be replaced in g_main_context_iterate().
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- * So, we should avoid accessing the old fd array (still pointed at by
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- * ufds) here in that case, since it might have been freed. We avoid this
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- * by not calling the collect stage.
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- */
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- if (last_ufds == ufds && n_ready < 0)
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- n_ready = select_thread_collect_poll (ufds, nfds);
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+ /* Note that, from this point onwards, ufds might point to freed memory! */
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+
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+ if (current_select_thread_serial == select_thread_start_serial)
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+ {
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+ if (n_ready < 0)
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+ n_ready = select_thread_collect_poll (current_ufds, nfds);
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+
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+ /* Nothing should be done in case no poll func recursion occurred
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+ * and n_ready > 0.
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+ */
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+ }
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+ else
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+ {
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+ /* In this case, a recursive invocation of the poll function has
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+ * collected results from the select thread. We clear the ufds
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+ * values so that stale poll results are not returned. In case
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+ * we did not receive results from start poll above, we also
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+ * set n_ready to zero.
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+ */
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+ int i;
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+
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+ n_ready = 0;
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+ for (i = 0; i < nfds; i++)
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+ current_ufds[i].revents = 0;
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+ }
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if (event &&
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[event type] == NSApplicationDefined &&
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--
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1.7.10.2 (Apple Git-33)
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