| commit | 350e27f5bdfe0b775d80a07ef2718c5c327fbb1c | [log] [tgz] |
|---|---|---|
| author | Matt Wolenetz <wolenetz@chromium.org> | Thu Jun 30 20:19:59 2022 |
| committer | Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> | Thu Jun 30 20:27:03 2022 |
| tree | 7599b5dec206142fb3e3746551412be9f71d215a | |
| parent | 86a82f4c942b664bc88e5f7b9cbb0d8945a388fb [diff] |
MSE-in-Workers: Switch MediaSourceHandle to be Transferable-only
Updates serialization logic to reflect current state of discussion of
MediaSourceHandle refinement in spec [1]:
* MediaSourceHandle was previously Serializable-only. With this change,
it is now Transferable-only. Data clone exception will occur if it is
attempted to be serialized without transfer. Data clone exception
will also occur if it is transferred more than once in same
postMessage, or if it has already been transferred.
* Updates MediaSourceHandleImpl to use "[[Detached]]" internal slot
semantic to know when a handle instance has already been transferred.
This is necessary, beyond just knowing if it has been serialized,
because otherwise the following scenario could not be enforced:
postMessage(null, [handle]); // Should succeed and detach handle.
// Then, this should fail because handle is already detached:
postMessage(handle, [handle]);
* Manual tests verified the scenario for the following matches similar
existing behavior for MessagePort transfer:
postMessage( {x: handle, y: handle}, [handle]); // should succeed
// on receipt: e.data.x === e.data.y should be true.
Existing handle-based MSE-in-Worker web-platform-tests are updated to
use transfer instead of just serialization to communicate the handles.
Later changes may add greater coverage, similar to coverage developed
locally while vetting this scenario and precedents like MessagePort
transfer.
Later change(s) may update the IDL and getHandle() implementation
according to similar spec discussion that has requested consideration
of using: [SameObject] handle() instead of current at-most-once
getHandle() success.
No change is made to the [[has_ever_been_used_as_srcObject]] logic: it
is still necessary to prevent transferring-away of a handle instance
once it has been assigned to the srcObject attribute of a media element.
[1] https://github.com/w3c/media-source/pull/306#issuecomment-1169155637
BUG=878133,1338956
Change-Id: Icb64aa712a0ce310984ca5fa0e9e02bd9ac428b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3733664
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Matthew Wolenetz <wolenetz@chromium.org>
Reviewed-by: Will Cassella <cassew@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1019793}
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