MAINT-5357: Add llcoro::yield() function to yield for one frame.

2 files changed, 15 insertions, 0 deletions

diff --git a/indra/llcommon/lleventcoro.cpp b/indra/llcommon/lleventcoro.cpp
index b7e7edec5a..ad02e139b8 100755
--- a/indra/llcommon/lleventcoro.cpp
+++ b/indra/llcommon/lleventcoro.cpp
@@ -145,6 +145,14 @@ void storeToLLSDPath(LLSD& dest, const LLSD& rawPath, const LLSD& value)
 
 } // anonymous
 
+void llcoro::yield()
+{
+    // By viewer convention, we post an event on the "mainloop" LLEventPump
+    // each iteration of the main event-handling loop. So waiting for a single
+    // event on "mainloop" gives us a one-frame yield.
+    waitForEventOn("mainloop");
+}
+
 LLSD llcoro::postAndWait(const LLSD& event, const LLEventPumpOrPumpName& requestPump,
                          const LLEventPumpOrPumpName& replyPump, const LLSD& replyPumpNamePath)
 {
diff --git a/indra/llcommon/lleventcoro.h b/indra/llcommon/lleventcoro.h
index f1c5dc2fde..e2ce4bb193 100755
--- a/indra/llcommon/lleventcoro.h
+++ b/indra/llcommon/lleventcoro.h
@@ -102,6 +102,13 @@ VoidListener<LISTENER> voidlistener(const LISTENER& listener)
 }
 
 /**
+ * Yield control from a coroutine for one "mainloop" tick. If your coroutine
+ * runs without suspending for nontrivial time, sprinkle in calls to this
+ * function to avoid stalling the rest of the viewer processing.
+ */
+void yield();
+
+/**
  * Post specified LLSD event on the specified LLEventPump, then wait for a
  * response on specified other LLEventPump. This is more than mere
  * convenience: the difference between this function and the sequence