auto merge of #3732 : mukilan/servo/xhr-issue-3630, r=jdm

This fixes issue #3630
A short summary of the changes:
* Use atomic generation id to cancel inflight requests
* Handles nested calls to abort, open, send inside handlers
* Adds XHRReleaseMsg to delay freeing XHR object till all
  inflight events are processed
* Handles both timeout, errors and abort/open in a symmetric fashion
  i.e All inflight events will be cancelled for timeouts, aborts,
    errors and on calling open.
* Change the ErroredMsg enum to be more symmetric with the returned
  Error enum

I noticed a few possible changes that could make the code for fetch task simpler:
* We can remove the additional timer task and let the fetch task manage 
  its own timer (or maybe the resource loader can do this.)
* The CORS related steps could also be moved into the resource loader.
* Right now upload events are not support. This requires some support 
  from resource loader. 

1 files changed, 4 insertions, 1 deletions

diff --git a/components/script/script_task.rs b/components/script/script_task.rs
index 7ef0d095545..5dd6f7c2d02 100644
--- a/components/script/script_task.rs
+++ b/components/script/script_task.rs
@@ -100,6 +100,8 @@ pub enum ScriptMsg {
     ExitWindowMsg(PipelineId),
     /// Notifies the script of progress on a fetch (dispatched to all tasks).
     XHRProgressMsg(TrustedXHRAddress, XHRProgress),
+    /// Releases one reference to the XHR object (dispatched to all tasks).
+    XHRReleaseMsg(TrustedXHRAddress),
     /// Message sent through Worker.postMessage (only dispatched to
     /// DedicatedWorkerGlobalScope).
     DOMMessage(*mut u64, size_t),
@@ -530,7 +532,8 @@ impl ScriptTask {
                 FromConstellation(ExitPipelineMsg(id)) => if self.handle_exit_pipeline_msg(id) { return false },
                 FromScript(ExitWindowMsg(id)) => self.handle_exit_window_msg(id),
                 FromConstellation(ResizeMsg(..)) => fail!("should have handled ResizeMsg already"),
-                FromScript(XHRProgressMsg(addr, progress)) => XMLHttpRequest::handle_xhr_progress(addr, progress),
+                FromScript(XHRProgressMsg(addr, progress)) => XMLHttpRequest::handle_progress(addr, progress),
+                FromScript(XHRReleaseMsg(addr)) => XMLHttpRequest::handle_release(addr),
                 FromScript(DOMMessage(..)) => fail!("unexpected message"),
                 FromScript(WorkerPostMessage(addr, data, nbytes)) => Worker::handle_message(addr, data, nbytes),
                 FromScript(WorkerRelease(addr)) => Worker::handle_release(addr),