Platform: Core: reduce latency on handling messages produced on the e…

…mulator thread
nba-emu · Jan 18, 2024 · d9e87f9 · d9e87f9
1 parent 3f7a202
commit d9e87f9
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Showing 2 changed files with 25 additions and 16 deletions.
diff --git a/src/platform/core/include/platform/emulator_thread.hpp b/src/platform/core/include/platform/emulator_thread.hpp
@@ -54,6 +54,7 @@ struct EmulatorThread {
 
   void PushMessage(const Message& message);
   void ProcessMessages();
+  void ProcessMessage(const Message& message);
 
   static constexpr int k_input_subsample_count = 4;
   static constexpr int k_cycles_per_second = 16777216;

diff --git a/src/platform/core/src/emulator_thread.cpp b/src/platform/core/src/emulator_thread.cpp
@@ -105,8 +105,15 @@ void EmulatorThread::PushMessage(const Message& message) {
     return;
   }
 
-  std::lock_guard lock_guard{msg_queue_mutex};
-  msg_queue.push(message); // @todo: maybe use emplace.
+  if(std::this_thread::get_id() == thread.get_id()) {
+    // Messages sent on the emulator thread (i.e. from a callback) do 
+    // not need to be pushed to the message queue.
+    // Process them right away instead to reduce latency.
+    ProcessMessage(message);
+  } else {
+    std::lock_guard lock_guard{msg_queue_mutex};
+    msg_queue.push(message); // @todo: maybe use emplace.
+  }
 }
 
 void EmulatorThread::ProcessMessages() {
@@ -115,22 +122,23 @@ void EmulatorThread::ProcessMessages() {
   std::lock_guard lock_guard{msg_queue_mutex};
 
   while(!msg_queue.empty()) {
-    const Message& message = msg_queue.front();
-
-    switch(message.type) {
-      case MessageType::Reset: {
-        core->Reset();
-        break;
-      }
-      case MessageType::SetKeyStatus: {
-        core->SetKeyStatus(message.set_key_status.key, message.set_key_status.pressed);
-        break;
-      }
-      default: Assert(false, "unhandled message type: {}", (int)message.type);
-    }
-
+    ProcessMessage(msg_queue.front());
     msg_queue.pop();
   }
 }
 
+void EmulatorThread::ProcessMessage(const Message& message) {
+  switch(message.type) {
+    case MessageType::Reset: {
+      core->Reset();
+      break;
+    }
+    case MessageType::SetKeyStatus: {
+      core->SetKeyStatus(message.set_key_status.key, message.set_key_status.pressed);
+      break;
+    }
+    default: Assert(false, "unhandled message type: {}", (int)message.type);
+  }
+}
+
 } // namespace nba