From e9134b045a6eea1d9bea2046ddcefb669ab6e016 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <[EMAIL REDACTED]>
Date: Thu, 6 Jan 2022 19:38:10 -0600
Subject: [PATCH] events: Only add sentinels for pumping done inside
SDL_WaitEventTimeout()
We don't want to catch explicit SDL_PumpEvents() calls by the application with
our polling check to avoid stale data. If the call to SDL_PumpEvents() produced
no events, there will be a sentinel sitting in the queue that will cause
SDL_PollEvent() to immediately return 0 next time it is called.
Our SDL_WaitEventTimeout() implementation avoids this issue by always popping
an event after calling SDL_PumpEvents(). This will remove the new sentinel if
we didn't get any new events.
---
src/events/SDL_events.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/src/events/SDL_events.c b/src/events/SDL_events.c
index 4459896e550..ff079c50ea9 100644
--- a/src/events/SDL_events.c
+++ b/src/events/SDL_events.c
@@ -809,7 +809,7 @@ SDL_FlushEvents(Uint32 minType, Uint32 maxType)
/* Run the system dependent event loops */
void
-SDL_PumpEvents(void)
+SDL_PumpEventsInternal(SDL_bool push_sentinel)
{
SDL_VideoDevice *_this = SDL_GetVideoDevice();
@@ -837,7 +837,7 @@ SDL_PumpEvents(void)
SDL_SendPendingSignalEvents(); /* in case we had a signal handler fire, etc. */
- if (SDL_GetEventState(SDL_POLLSENTINEL) == SDL_ENABLE) {
+ if (push_sentinel && SDL_GetEventState(SDL_POLLSENTINEL) == SDL_ENABLE) {
SDL_Event sentinel;
SDL_zero(sentinel);
@@ -846,6 +846,12 @@ SDL_PumpEvents(void)
}
}
+void
+SDL_PumpEvents()
+{
+ SDL_PumpEventsInternal(SDL_FALSE);
+}
+
/* Public functions */
int
@@ -885,7 +891,7 @@ SDL_WaitEventTimeout_Device(_THIS, SDL_Window *wakeup_window, SDL_Event * event,
c) Periodic processing that takes place in some platform PumpEvents() functions happens
d) Signals received in WaitEventTimeout() are turned into SDL events
*/
- SDL_PumpEvents();
+ SDL_PumpEventsInternal(SDL_TRUE);
if (!_this->wakeup_lock || SDL_LockMutex(_this->wakeup_lock) == 0) {
int status = SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT);
@@ -984,7 +990,7 @@ SDL_WaitEventTimeout(SDL_Event * event, int timeout)
/* If there isn't a poll sentinel event pending, pump events and add one */
if (SDL_AtomicGet(&SDL_sentinel_pending) == 0) {
- SDL_PumpEvents();
+ SDL_PumpEventsInternal(SDL_TRUE);
}
/* First check for existing events */
@@ -1031,7 +1037,7 @@ SDL_WaitEventTimeout(SDL_Event * event, int timeout)
}
for (;;) {
- SDL_PumpEvents();
+ SDL_PumpEventsInternal(SDL_TRUE);
switch (SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT)) {
case -1:
return 0;