From f48187449ed4772044da55a8a3745d578c1b8c48 Mon Sep 17 00:00:00 2001
From: David Marcec <dmarcecguzman@gmail.com>
Date: Thu, 16 Jul 2020 18:38:35 +1000
Subject: Use conditional var

---
 src/video_core/shader/async_shaders.cpp | 14 +++++++++-----
 src/video_core/shader/async_shaders.h   | 10 ++++++----
 2 files changed, 15 insertions(+), 9 deletions(-)

(limited to 'src/video_core/shader')

diff --git a/src/video_core/shader/async_shaders.cpp b/src/video_core/shader/async_shaders.cpp
index fb94ac2e7..84d86c32f 100644
--- a/src/video_core/shader/async_shaders.cpp
+++ b/src/video_core/shader/async_shaders.cpp
@@ -59,7 +59,6 @@ void AsyncShaders::KillWorkers() {
 }
 
 bool AsyncShaders::HasWorkQueued() {
-    std::shared_lock lock(queue_mutex);
     return !pending_queue.empty();
 }
 
@@ -118,26 +117,31 @@ void AsyncShaders::QueueOpenGLShader(const OpenGL::Device& device,
                         cpu_addr};
     std::unique_lock lock(queue_mutex);
     pending_queue.push_back(std::move(params));
+    cv.notify_one();
 }
 
 void AsyncShaders::ShaderCompilerThread(Core::Frontend::GraphicsContext* context) {
     using namespace std::chrono_literals;
     while (!is_thread_exiting.load(std::memory_order_relaxed)) {
+        std::unique_lock<std::mutex> lock(queue_mutex);
+        cv.wait(lock, [&] { return HasWorkQueued() || is_thread_exiting; });
+        if (is_thread_exiting) {
+            return;
+        }
+
         // Partial lock to allow all threads to read at the same time
         if (!HasWorkQueued()) {
             continue;
         }
-        // Complete lock for pulling workload
-        queue_mutex.lock();
         // Another thread beat us, just unlock and wait for the next load
         if (pending_queue.empty()) {
-            queue_mutex.unlock();
             continue;
         }
         // Pull work from queue
         WorkerParams work = std::move(pending_queue.front());
         pending_queue.pop_front();
-        queue_mutex.unlock();
+
+        lock.unlock();
 
         if (work.backend == AsyncShaders::Backend::OpenGL ||
             work.backend == AsyncShaders::Backend::GLASM) {
diff --git a/src/video_core/shader/async_shaders.h b/src/video_core/shader/async_shaders.h
index 26bc38326..2f5ee94ad 100644
--- a/src/video_core/shader/async_shaders.h
+++ b/src/video_core/shader/async_shaders.h
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <condition_variable>
 #include <deque>
 #include <memory>
 #include <shared_mutex>
@@ -59,9 +60,6 @@ public:
     // Force end all threads
     void KillWorkers();
 
-    /// Check our worker queue to see if we have any work queued already
-    bool HasWorkQueued();
-
     /// Check to see if any shaders have actually been compiled
     bool HasCompletedWork();
 
@@ -81,6 +79,9 @@ public:
 private:
     void ShaderCompilerThread(Core::Frontend::GraphicsContext* context);
 
+    /// Check our worker queue to see if we have any work queued already
+    bool HasWorkQueued();
+
     struct WorkerParams {
         AsyncShaders::Backend backend;
         OpenGL::Device device;
@@ -94,7 +95,8 @@ private:
         VAddr cpu_address;
     };
 
-    std::shared_mutex queue_mutex;
+    std::condition_variable cv;
+    std::mutex queue_mutex;
     std::shared_mutex completed_mutex;
     std::atomic<bool> is_thread_exiting{};
     std::vector<std::unique_ptr<Core::Frontend::GraphicsContext>> context_list;
-- 
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