From 6642734aa86cddbf8ce5252062127d14feb8d074 Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Sat, 18 Apr 2020 12:37:58 -0700
Subject: [PATCH] Removes the dumb timer wait for idle

Turns out my Threadripper stomps these tests so the arbitrary wait time
actually slows down my unit test time.
Don't want to make it shorter since `strace -f` becomes ugly at that
point.
Instead set up a semaphore style waiting structure that waits until
there are no longer any participants in the atomic
---
 .../Source/Interface/Context/Context.h        |  5 +++
 .../FEXCore/Source/Interface/Core/Core.cpp    | 36 ++++++++-----------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/External/FEXCore/Source/Interface/Context/Context.h b/External/FEXCore/Source/Interface/Context/Context.h
index 62a007aa7..f8f228bb3 100644
--- a/External/FEXCore/Source/Interface/Context/Context.h
+++ b/External/FEXCore/Source/Interface/Context/Context.h
@@ -65,6 +65,11 @@ namespace FEXCore::Context {
     FEXCore::Core::InternalThreadState* ParentThread;
     std::vector<FEXCore::Core::InternalThreadState*> Threads;
     std::atomic_bool ShouldStop{};
+
+    std::mutex IdleWaitMutex;
+    std::condition_variable IdleWaitCV;
+    std::atomic<uint32_t> IdleWaitRefCount{};
+
     Event PauseWait;
     bool Running{};
     CoreRunningMode RunningMode {CoreRunningMode::MODE_RUN};
diff --git a/External/FEXCore/Source/Interface/Core/Core.cpp b/External/FEXCore/Source/Interface/Core/Core.cpp
index bb45dda66..996e63715 100644
--- a/External/FEXCore/Source/Interface/Core/Core.cpp
+++ b/External/FEXCore/Source/Interface/Core/Core.cpp
@@ -314,26 +314,10 @@ namespace FEXCore::Context {
   }
 
   void Context::WaitForIdle() {
-    do {
-      bool AllPaused = true;
-      {
-        std::lock_guard<std::mutex> lk(ThreadCreationMutex);
-        {
-          // Grab the mutex lock so a thread doesn't try and spin up while we are waiting
-          for (size_t i = 0; i < Threads.size(); ++i) {
-            if (Threads[i]->State.RunningEvents.Running.load() || Threads[i]->State.RunningEvents.WaitingToStart.load()) {
-              AllPaused = false;
-              break;
-            }
-          }
-        }
-      }
-
-      if (AllPaused)
-        break;
-
-      PauseWait.WaitFor(std::chrono::milliseconds(250));
-    } while (true);
+    std::unique_lock<std::mutex> lk(IdleWaitMutex);
+    IdleWaitCV.wait(lk, [this] {
+      return IdleWaitRefCount.load() == 0;
+    });
 
     Running = false;
   }
@@ -656,6 +640,7 @@ namespace FEXCore::Context {
 
     // Let's do some initial bookkeeping here
     Thread->State.ThreadManager.TID = ::gettid();
+    ++IdleWaitRefCount;
 
     // Now notify the thread that we are initialized
     Thread->ThreadWaiting.NotifyAll();
@@ -666,6 +651,9 @@ namespace FEXCore::Context {
       Thread->State.RunningEvents.ShouldStop.store(true);
       Thread->State.RunningEvents.Running.store(false);
       Thread->ExitReason = FEXCore::Context::ExitReason::EXIT_SHUTDOWN;
+
+      --IdleWaitRefCount;
+      IdleWaitCV.notify_all();
       return;
     }
 
@@ -797,6 +785,9 @@ namespace FEXCore::Context {
             ShouldStop = true;
             Thread->ExitReason = FEXCore::Context::ExitReason::EXIT_SHUTDOWN;
           }
+
+          --IdleWaitRefCount;
+          IdleWaitCV.notify_all();
           break;
         }
 
@@ -808,8 +799,10 @@ namespace FEXCore::Context {
           if (Thread->ExitReason == FEXCore::Context::ExitReason::EXIT_NONE)
             Thread->ExitReason = FEXCore::Context::ExitReason::EXIT_DEBUG;
 
-          HandleExit(Thread);
+          --IdleWaitRefCount;
+          IdleWaitCV.notify_all();
 
+          HandleExit(Thread);
 
           Thread->StartRunning.Wait();
 
@@ -819,6 +812,7 @@ namespace FEXCore::Context {
             Thread->ExitReason = FEXCore::Context::ExitReason::EXIT_NONE;
 
           Thread->State.RunningEvents.Running = true;
+          ++IdleWaitRefCount;
         }
       }
     }