From 754053e73fc39573d17a82e17b59ca25f23f171e Mon Sep 17 00:00:00 2001
From: Lion Kortlepel <development@kortlepel.com>
Date: Thu, 3 Feb 2022 18:57:52 +0100
Subject: [PATCH] Use yield() where possible

Replaced calls of this_thread::sleep_* with this_thread::yield(), which
yields the thread to the OS' scheduler.
---
 include/TLuaEngine.h |  1 +
 src/TConsole.cpp     |  2 +-
 src/TLuaEngine.cpp   | 34 ++++++++++++++--------------------
 src/TPPSMonitor.cpp  |  4 ++--
 4 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/include/TLuaEngine.h b/include/TLuaEngine.h
index 1673c61..9b0a884 100644
--- a/include/TLuaEngine.h
+++ b/include/TLuaEngine.h
@@ -149,6 +149,7 @@ public:
     void CancelEventTimers(const std::string& EventName, TLuaStateId StateId);
     sol::state_view GetStateForPlugin(const fs::path& PluginPath);
     TLuaStateId GetStateIDForPlugin(const fs::path& PluginPath);
+    void AddResultToCheck(const std::shared_ptr<TLuaResult>& Result);
 
     static constexpr const char* BeamMPFnNotFoundError = "BEAMMP_FN_NOT_FOUND";
 
diff --git a/src/TConsole.cpp b/src/TConsole.cpp
index 79df8d2..827881c 100644
--- a/src/TConsole.cpp
+++ b/src/TConsole.cpp
@@ -386,7 +386,7 @@ TConsole::TConsole() {
                 } else {
                     auto Future = mLuaEngine->EnqueueScript(mStateId, { std::make_shared<std::string>(cmd), "", "" });
                     while (!Future->Ready) {
-                        std::this_thread::sleep_for(std::chrono::milliseconds(1)); // TODO: Add a timeout
+                        std::this_thread::yield(); // TODO: Add a timeout
                     }
                     if (Future->Error) {
                         beammp_lua_error(Future->ErrorMessage);
diff --git a/src/TLuaEngine.cpp b/src/TLuaEngine.cpp
index 89742e2..41ffb96 100644
--- a/src/TLuaEngine.cpp
+++ b/src/TLuaEngine.cpp
@@ -54,25 +54,17 @@ void TLuaEngine::operator()() {
     auto ResultCheckThread = std::thread([&] {
         RegisterThread("ResultCheckThread");
         while (!mShutdown) {
-            std::this_thread::sleep_for(std::chrono::milliseconds(100));
+            std::this_thread::sleep_for(std::chrono::milliseconds(10));
             std::unique_lock Lock(mResultsToCheckMutex);
             if (!mResultsToCheck.empty()) {
                 auto Res = mResultsToCheck.front();
                 mResultsToCheck.pop();
                 Lock.unlock();
 
-                size_t Waited = 0;
-                while (!Res->Ready) {
-                    std::this_thread::sleep_for(std::chrono::milliseconds(1));
-                    Waited++;
-                    if (Waited > 250) {
-                        // FIXME: This should *eventually* timeout.
-                        // beammp_lua_error(Res->Function + " in " + Res->StateId + " took >1s to respond, not printing possible errors");
-                        Lock.lock();
-                        mResultsToCheck.push(Res);
-                        Lock.unlock();
-                        break;
-                    }
+                if (!Res->Ready) {
+                    Lock.lock();
+                    mResultsToCheck.push(Res);
+                    Lock.unlock();
                 }
                 if (Res->Error) {
                     if (Res->ErrorMessage != BeamMPFnNotFoundError) {
@@ -80,13 +72,14 @@ void TLuaEngine::operator()() {
                     }
                 }
             }
+            std::this_thread::yield();
         }
     });
     // event loop
     auto Before = std::chrono::high_resolution_clock::now();
     while (!mShutdown) {
         if (mLuaStates.size() == 0) {
-            std::this_thread::sleep_for(std::chrono::seconds(500));
+            std::this_thread::sleep_for(std::chrono::seconds(100));
         }
         { // Timed Events Scope
             std::unique_lock Lock(mTimedEventsMutex);
@@ -149,6 +142,11 @@ TLuaStateId TLuaEngine::GetStateIDForPlugin(const fs::path& PluginPath) {
     return "";
 }
 
+void TLuaEngine::AddResultToCheck(const std::shared_ptr<TLuaResult>& Result) {
+    std::unique_lock Lock(mResultsToCheckMutex);
+    mResultsToCheck.push(Result);
+}
+
 void TLuaEngine::WaitForAll(std::vector<std::shared_ptr<TLuaResult>>& Results, const std::optional<std::chrono::high_resolution_clock::duration>& Max) {
     for (const auto& Result : Results) {
         bool Cancelled = false;
@@ -705,6 +703,7 @@ void TLuaEngine::StateThreadData::AddPath(const fs::path& Path) {
 
 void TLuaResult::WaitUntilReady() {
     while (!Ready) {
+        std::this_thread::yield();
         std::this_thread::sleep_for(std::chrono::milliseconds(10));
     }
 }
@@ -762,12 +761,7 @@ void TPluginMonitor::operator()() {
                     auto StateID = mEngine.GetStateIDForPlugin(fs::path(Pair.first).parent_path());
                     auto Res = mEngine.EnqueueScript(StateID, Chunk);
                     // TODO: call onInit
-                    while (!Res->Ready) {
-                        std::this_thread::sleep_for(std::chrono::milliseconds(10));
-                    }
-                    if (Res->Error) {
-                        beammp_lua_error(Res->ErrorMessage);
-                    }
+                    mEngine.AddResultToCheck(Res);
                 } else {
                     // TODO: trigger onFileChanged event
                     beammp_trace("Change detected in file \"" + Pair.first + "\", event trigger not implemented yet");
diff --git a/src/TPPSMonitor.cpp b/src/TPPSMonitor.cpp
index 8d58d84..b5b4951 100644
--- a/src/TPPSMonitor.cpp
+++ b/src/TPPSMonitor.cpp
@@ -21,8 +21,8 @@ TPPSMonitor::TPPSMonitor(TServer& Server)
 void TPPSMonitor::operator()() {
     RegisterThread("PPSMonitor");
     while (!mNetwork) {
-        // hard spi
-        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+        // hard(-ish) spin
+        std::this_thread::yield();
     }
     beammp_debug("PPSMonitor starting");
     Application::SetSubsystemStatus("PPSMonitor", Application::Status::Good);