[Lldb-commits] [lldb] [lldb] Add timed callbacks to the MainLoop class (PR #112895)

[Jacob Lalonde via lldb-commits]

================
@@ -7,27 +7,43 @@
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Host/MainLoopBase.h"
+#include <chrono>
 
 using namespace lldb;
 using namespace lldb_private;
 
-void MainLoopBase::AddPendingCallback(const Callback &callback) {
+void MainLoopBase::AddCallback(const Callback &callback, TimePoint point) {
+  bool interrupt_needed;
   {
     std::lock_guard<std::mutex> lock{m_callback_mutex};
-    m_pending_callbacks.push_back(callback);
+    // We need to interrupt the main thread if this callback is scheduled to
+    // execute at an earlier time than the earliest callback registered so far.
+    interrupt_needed = m_callbacks.empty() || point < m_callbacks.top().first;
+    m_callbacks.emplace(point, callback);
   }
-  TriggerPendingCallbacks();
+  if (interrupt_needed)
----------------
Jlalond wrote:

> I think you're misunderstanding something here. The emplace is always fast - it just adds > something to the queue and doesn't cause any callbacks to run. The callbacks will always > be run on the mainloop thread. The interrupt needs to happen after the insertion to make > sure the other thread observes the new callback (via the result of GetNextWakeupTime).

My concern was purely if we want nanosecond precision, adding into a priority queue (assuming N log N) seemed like it could be slow.

On a second look, I think my concern is moot

https://github.com/llvm/llvm-project/pull/112895