auto merge of #4536 : mrobinson/servo/pixmap, r=pcwalton

It is possible for a PaintTask to start exiting soon after sending new
buffers to the compositor. In that case, the compositor should return
the now unnecessary buffers to the PaintTask so that it can properly
free them.

To accomplish this, the compositor now keeps a hash map of paint task
channels per pipeline id. When a PaintTask exists, the constellation
informs the compositor that it can forget about it. Additionally, the
PaintTask should not wait for any buffers when the engine is doing a
complete shutdown. In that case, the compositor is already halted and
has simply let all buffers leak. We pipe through the shutdown type when
destroying the pipeline to make this decision.

Fixes #2641.

1 files changed, 7 insertions, 0 deletions

diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index 78cda641aef..e9e69c669c7 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -253,3 +253,10 @@ pub struct PipelineId(pub uint);
 
 #[deriving(Clone, PartialEq, Eq, Hash, Show)]
 pub struct SubpageId(pub uint);
+
+// The type of pipeline exit. During complete shutdowns, pipelines do not have to
+// release resources automatically released on process termination.
+pub enum PipelineExitType {
+    PipelineOnly,
+    Complete,
+}