This patch removes a lot of code involved with observing the refresh driver from
nsAnimationManager and nsTransitionManager now that we no longer need to do
this.
The one piece it does not remove, however, is
AnimationCollection::mNeedsRefreshes since this flag actually serves a secondary
purpose in telling us when the animation style has not changed and so does
not need to be updated. A subsequent patch in this series will rename this
and update the code that makes use of it.
This patch adds a test that even when we seek from being irrelevant to another
state where we no longer need ticks that we still spin the refresh driver
in order to queue and dispatch an animationstart event.
Currently AnimationTimeline stores animations in a hashmap which means that
when we go to iterate over those animations to tick them we will visit them
in an order that is non-deterministic.
Although many of the observable effects of ticking an animation (e.g. CSS
animation/transition events, mutation observer events) are later sorted so that
the result does not depend on the order in which animations are ticked, this is
not true for in all cases. In particular, the order in which Animation.finished
promises are resolved will vary depending on the order in which animations are
ticked. Likewise, for Animation finish events.
Furthermore, it seems generally desirable to have a deterministic order for
visiting animations in order to aid reproducing bugs.
To achieve this, this patch switches the storage of animations in
AnimationTimeline to use an array instead. However, when adding animations
we need to determine if the animation to add already exists. To this end we
also maintain a hashmap of the animations so we can quickly determine if
the animation to add is a duplicate or not.
Now that DocumentTimeline observes the refresh driver we can use regular
ticks to remove unnecessary animations.
We do this because in a subsequent patch, in order to provide deterministic
enumeration order when ticking animations, we will store animations in an array.
Removing an arbitrary element from an nsTArray is O(n) since we have to search
for the array index first, or O(log n) if we keep the array sorted. If we
destroy a subtree containing n animations, the operation effectively becomes
O(n^2), or, if we keep the array sorted, O(n log n). By destroying during a
tick when we are already iterating over the array, however, we will be able
to do this much more efficiently.
Whether an animation is newly associated with a timeline, or is disassociated
from a timeline, or if it merely has its timing updated, the behavior
implemented in this patch is to simply make sure we are observing the refresh
driver and deal with the animation on the next tick.
It might seem that we could be a lot more clever about this and, for example, if
an animation reports NeedsTicks() == false, not start observing the refresh
driver. There are various edge cases however that need to be taken into account.
For example, if a CSS animation is finished (IsRelevant() == false so that
animation will have been removed from the timeline), and paused
(NeedsTicks() == false), and we seek it back to the point where it is relevant
again, we actually need to observe the refresh driver so that it can dispatch an
animationstart event on the next tick. A test case in a subsequent patch tests
this specific situation.
We could possibly add logic to detect if we need to fire events on the next tick
but the complexity does not seem warranted given that even if we unnecessarily
start observing the refresh driver, we will stop watching it on the next tick.
This patch removes some rather lengthy comments from
AnimationTiming::UpdateTiming. This is, in part, because of the behavior
described above that makes these comments no longer relevant. Other parts are
removed because the Web Animations specification has been updated such that a
timeline becoming inactive now pauses the animation[1] so that the issue
regarding detecting timelines becoming active/inactive no longer applies
since animations attached to an inactive timeline remain "relevant".
[1] https://w3c.github.io/web-animations/#responding-to-a-newly-inactive-timeline
Adds a method to determine if an animation requires refresh driver ticks.
We will use this function later to determine when it is safe to stop
observing the refresh driver.
Also...
- Rename various "operator" identifiers as "op" to match |CompositionOp|.
- Rename |nsBackgroundLayerState::mCompositingOp| as |mCompositionOp| to match
|CompositionOp|.
- Remove some deprecated functions that are no longer needed.
--HG--
extra : rebase_source : 74e9b6eecf6f442e27cc18fd4ae6f668a45188aa
This is found by Viva64. Because the data we're memsetting to 0
may not be used after this point, the compiler can eliminate the
memsets. We need to roll our own inline memset that cannot be
optimized away.
This commit creates the HeapSnapshotFileActor and moves the transferHeapSnapshot
method from MemoryActor to HeapSnapshotFileActor. This is necessary because
child processes in e10s are sandboxed and do not have access to the file system,
and because MemoryActor is in the sandboxed child process it cannot open the
file and send it over the RDP.
This complexity is hidden at the MemoryFront layer. Users of MemoryFront will
still simply call its saveHeapSnapshot method, and do not need to worry about
the inner workings of how heap snapshot files are transferred over the RDP. This
required adding a third parameter to MemoryFront's initialize method: the
listTabs response.
