Merge lp:~vanvugt/mir/swap-then-drop into lp:mir

[Daniel van Vugt]

Reorder gl::Renderer::render so that GL calls which don't affect screen
contents are not in the way of swap_buffers.

The difference is probably never noticeable but theoretically this gets
swap_buffers started marginally earlier.

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:4090
https://mir-jenkins.ubuntu.com/job/mir-ci/3174/
Executed test runs:
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-mir/4265
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/4352
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/4342
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial+overlay/4342
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=zesty/4342
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4292/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4292/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4292/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4292/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4292/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4292
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4292/artifact/output/*zip*/output.zip

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Alan Griffiths (alan-griffiths)]

Sure, why not.

review: Approve

[Chris Halse Rogers (raof)]

Indeed.

review: Approve

=== modified file 'src/renderers/gl/renderer.cpp'
--- src/renderers/gl/renderer.cpp	2017-02-15 09:38:53 +0000
+++ src/renderers/gl/renderer.cpp	2017-03-16 04:16:06 +0000
@@ -212,9 +212,11 @@
     for (auto const& r : renderables)
         draw(*r, r->alpha() < 1.0f ? alpha_program : default_program);
 
+    render_target.swap_buffers();
+
+    // Deleting unused textures only requires the GL context. This clean-up
+    // does not affect screen contents so can happen after swap_buffers...
     texture_cache->drop_unused();
-
-    render_target.swap_buffers();
 }
 
 void mrg::Renderer::draw(mg::Renderable const& renderable,