From c613ead5fa2361296cf8d9a80d4648492ff4e16f Mon Sep 17 00:00:00 2001
From: Juan Linietsky <reduzio@gmail.com>
Date: Mon, 29 Jul 2019 12:59:18 -0300
Subject: Added a spinlock template as well as a thread work pool class.

Also, optimized shader compilation to happen on threads.
---
 core/thread_work_pool.h | 78 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 core/thread_work_pool.h

(limited to 'core/thread_work_pool.h')

diff --git a/core/thread_work_pool.h b/core/thread_work_pool.h
new file mode 100644
index 0000000000..165eb391e2
--- /dev/null
+++ b/core/thread_work_pool.h
@@ -0,0 +1,78 @@
+#ifndef THREAD_WORK_POOL_H
+#define THREAD_WORK_POOL_H
+
+#include "core/os/memory.h"
+#include "core/os/semaphore.h"
+#include <atomic>
+#include <thread>
+class ThreadWorkPool {
+
+	std::atomic<uint32_t> index;
+
+	struct BaseWork {
+		std::atomic<uint32_t> *index;
+		uint32_t max_elements;
+		virtual void work() = 0;
+	};
+
+	template <class C, class M, class U>
+	struct Work : public BaseWork {
+		C *instance;
+		M method;
+		U userdata;
+		virtual void work() {
+
+			while (true) {
+				uint32_t work_index = index->fetch_add(1, std::memory_order_relaxed);
+				if (work_index >= max_elements) {
+					break;
+				}
+				(instance->*method)(work_index, userdata);
+			}
+		}
+	};
+
+	struct ThreadData {
+		std::thread *thread;
+		Semaphore start;
+		Semaphore completed;
+		std::atomic<bool> exit;
+		BaseWork *work;
+	};
+
+	ThreadData *threads = nullptr;
+	uint32_t thread_count = 0;
+
+	static void _thread_function(ThreadData *p_thread);
+
+public:
+	template <class C, class M, class U>
+	void do_work(uint32_t p_elements, C *p_instance, M p_method, U p_userdata) {
+
+		ERR_FAIL_COND(!threads); //never initialized
+
+		index.store(0);
+
+		Work<C, M, U> *w = memnew((Work<C, M, U>));
+		w->instance = p_instance;
+		w->userdata = p_userdata;
+		w->method = p_method;
+		w->index = &index;
+		w->max_elements = p_elements;
+
+		for (uint32_t i = 0; i < thread_count; i++) {
+			threads[i].work = w;
+			threads[i].start.post();
+		}
+		for (uint32_t i = 0; i < thread_count; i++) {
+			threads[i].completed.wait();
+			threads[i].work = nullptr;
+		}
+	}
+
+	void init(int p_thread_count = -1);
+	void finish();
+	~ThreadWorkPool();
+};
+
+#endif // THREAD_POOL_H
-- 
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