Enable (when available) and improve performance of persistently mapped buffer path for the vertex/index buffers used with automatic batching.

--HG--
branch : minor

src/modules/graphics/opengl/FenceSync.cpp

@@ -0,0 +1,147 @@
+/**
+ * Copyright (c) 2006-2017 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+
+#include "FenceSync.h"
+
+namespace love
+{
+namespace graphics
+{
+namespace opengl
+{
+
+FenceSync::~FenceSync()
+{
+	cleanup();
+}
+
+bool FenceSync::fence()
+{
+	bool wasActive = sync != 0;
+
+	if (wasActive)
+		cleanup();
+
+	sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+
+	return !wasActive;
+}
+
+bool FenceSync::cpuWait()
+{
+	if (sync == 0)
+		return false;
+
+	GLbitfield flags = 0;
+	GLuint64 duration = 0;
+
+	while (true)
+	{
+		GLenum status = glClientWaitSync(sync, flags, duration);
+
+		if (status == GL_ALREADY_SIGNALED || status == GL_CONDITION_SATISFIED)
+			break;
+
+		if (status == GL_WAIT_FAILED)
+			break;
+
+		flags = GL_SYNC_FLUSH_COMMANDS_BIT;
+		duration = 1000000000; // 1 second in nanoseconds.
+	}
+
+	cleanup();
+
+	return true;
+}
+
+void FenceSync::cleanup()
+{
+	if (sync != 0)
+	{
+		glDeleteSync(sync);
+		sync = 0;
+	}
+}
+
+BufferSync::~BufferSync()
+{
+	cleanup();
+}
+
+void BufferSync::lock(size_t start, size_t length)
+{
+	Range range = {start, length};
+	GLsync sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+	locks.emplace_back(range, sync);
+}
+
+void BufferSync::wait(size_t start, size_t length)
+{
+	Range range = {start, length};
+	int lockcount = (int) locks.size();
+
+	for (int i = 0; i < lockcount; i++)
+	{
+		if (range.overlaps(locks[i].range))
+		{
+			syncWait(locks[i].sync);
+			glDeleteSync(locks[i].sync);
+
+			locks[i] = locks[lockcount - 1];
+			locks.pop_back();
+
+			--lockcount;
+			--i;
+		}
+	}
+}
+
+void BufferSync::cleanup()
+{
+	for (const auto &lock : locks)
+		glDeleteSync(lock.sync);
+
+	locks.clear();
+}
+
+void BufferSync::syncWait(GLsync sync)
+{
+	GLbitfield flags = 0;
+	GLuint64 duration = 0;
+
+	while (true)
+	{
+		GLenum status = glClientWaitSync(sync, flags, duration);
+
+		if (status == GL_ALREADY_SIGNALED || status == GL_CONDITION_SATISFIED)
+			return;
+
+		if (status == GL_WAIT_FAILED)
+			return;
+
+		flags = GL_SYNC_FLUSH_COMMANDS_BIT;
+		duration = 1000000000; // 1 second in nanoseconds.
+	}
+}
+
+} // opengl
+} // graphics
+} // love