From ce91218b420cd9e57a3367679300f8ba4027d6c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Konstantin=20K=C3=A4fer?= <mail@kkaefer.com>
Date: Wed, 12 Jun 2019 17:25:44 +0200
Subject: [core] don't call glFlush on every frame

---
 src/mbgl/gfx/context.hpp            | 3 +++
 src/mbgl/gl/context.cpp             | 6 ++++++
 src/mbgl/gl/context.hpp             | 2 ++
 src/mbgl/renderer/renderer_impl.cpp | 2 +-
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/mbgl/gfx/context.hpp b/src/mbgl/gfx/context.hpp
index 64eddf3e5a..2c7cb14899 100644
--- a/src/mbgl/gfx/context.hpp
+++ b/src/mbgl/gfx/context.hpp
@@ -38,6 +38,9 @@ public:
     // Called at the end of a frame.
     virtual void performCleanup() = 0;
 
+    // Called when the app receives a memory warning and before it goes to the background.
+    virtual void reduceMemoryUsage() = 0;
+
 public:
     virtual std::unique_ptr<OffscreenTexture>
         createOffscreenTexture(Size,
diff --git a/src/mbgl/gl/context.cpp b/src/mbgl/gl/context.cpp
index 3e88624d4f..4d9c2055de 100644
--- a/src/mbgl/gl/context.cpp
+++ b/src/mbgl/gl/context.cpp
@@ -682,7 +682,13 @@ void Context::performCleanup() {
                                                abandonedRenderbuffers.data()));
         abandonedRenderbuffers.clear();
     }
+}
+
+void Context::reduceMemoryUsage() {
+    performCleanup();
 
+    // Ensure that all pending actions are executed to ensure that they happen before the app goes
+    // to the background.
     MBGL_CHECK_ERROR(glFinish());
 }
 
diff --git a/src/mbgl/gl/context.hpp b/src/mbgl/gl/context.hpp
index 80278718d1..70f12e5a8d 100644
--- a/src/mbgl/gl/context.hpp
+++ b/src/mbgl/gl/context.hpp
@@ -96,6 +96,8 @@ public:
     // Only call this while the OpenGL context is exclusive to this thread.
     void performCleanup() override;
 
+    void reduceMemoryUsage() override;
+
     // Drain pools and remove abandoned objects, in preparation for destroying the store.
     // Only call this while the OpenGL context is exclusive to this thread.
     void reset();
diff --git a/src/mbgl/renderer/renderer_impl.cpp b/src/mbgl/renderer/renderer_impl.cpp
index 96ba8d7554..c7cca3a659 100644
--- a/src/mbgl/renderer/renderer_impl.cpp
+++ b/src/mbgl/renderer/renderer_impl.cpp
@@ -666,7 +666,7 @@ void Renderer::Impl::reduceMemoryUse() {
     for (const auto& entry : renderSources) {
         entry.second->reduceMemoryUse();
     }
-    backend.getContext().performCleanup();
+    backend.getContext().reduceMemoryUsage();
     imageManager->reduceMemoryUse();
     observer->onInvalidate();
 }
-- 
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