There are a number of operations with the surface cache which may result
in individual surfaces for a particular image cache to be removed. If an
image cache is emptied, and we are in factor of 2 mode, we should reset
it to the default mode, because we require at least one surface to be
available to determine the native/ideal size. Additionally, if the cache
is not locked, it should be removed entirely from the surface cache. We
handle this correctly in methods such as Lookup and LookupBestMatch, but
Prune and CollectSizeOfSurfaces can also cause this to happen, as
recently done in bug 1370412 and bug 1380649.
When we lookup a surface in the cache, we are careful to remove any
surfaces which were backed by volatile memory and got purged before we
could reacquire the buffer. We were not so careful in doing that when
generating memory reports. ISurfaceProvider::AddSizeOfExcludingThis will
cause us to acquire the buffer, and if it was purged, forget about its
purged status. Later when we performed a lookup, we would forget the
purged status, and assume we have the right data. This would appear as
completely transparent for BGRA surfaces, and completely black for BGRX
surfaces.
With this patch, we now properly remove purged surfaces instead of
including them in the report. This ensures that the cache state is
consistent. This also resolves memory reports of surfaces which reported
using no data -- they were purged when the report was generated.
Additionally, there was a bug in SurfaceCache::PruneImage where we did
not discard surfaces outside the module lock. Both PruneImage and
CollectSizeOfSurfaces now free any discarded surfaces outside the lock.
When we lookup a surface in the cache, we are careful to remove any
surfaces which were backed by volatile memory and got purged before we
could reacquire the buffer. We were not so careful in doing that when
generating memory reports. ISurfaceProvider::AddSizeOfExcludingThis will
cause us to acquire the buffer, and if it was purged, forget about its
purged status. Later when we performed a lookup, we would forget the
purged status, and assume we have the right data. This would appear as
completely transparent for BGRA surfaces, and completely black for BGRX
surfaces.
With this patch, we now properly remove purged surfaces instead of
including them in the report. This ensures that the cache state is
consistent. This also resolves memory reports of surfaces which reported
using no data -- they were purged when the report was generated.
Additionally, there was a bug in SurfaceCache::PruneImage where we did
not discard surfaces outside the module lock. Both PruneImage and
CollectSizeOfSurfaces now free any discarded surfaces outside the lock.
When the surface cache starts tracking an unlocked surface, it must
insert it into the expiration tracker, so that it can be freed later if
it is remains unused. ExpirationTrackerImpl::AddObjectLocked can fail
due to out-of-memory conditions or during shutdown, which we previously
ignored, and could leave us in a state where we think the surface is in
the tracker but is not. When we later try to mark the surface as used in
the tracker, it will hit a release assert because it doesn't exist. Now
we handle the insertion failure by discarding the surface. Marking the
surface as used can itself encounter a similar issue, and we handle it
the same way.
MozReview-Commit-ID: Kv6l0znnG48
An ImageSurfaceCache cannot enter factor-of-2 mode without a minimum
number of surfaces being present in its cache. However those surfaces
can be purged from the cache through various means (expire due to being
disuse, volatile buffers purged, etc). Also, it is entirely possible
that all the surfaces get purged, but the cache itself remains. Since
factor-of-2 mode requires at least one surface (to get the owning image
and its native size), we need to handle the case when the cache is
emptied appropriately. As such, we now reset the factor-of-2 mode (and
its pruned state) to the default (false) if we transition from non-empty
to empty.
MozReview-Commit-ID: EVaEqW59Asv
The SurfaceCache can hold the first frame of a "static" decode as well as the animated frames in two seperate entries. We only care about what happens to the animated frames, so ignore OnSurfaceDiscarded for anything else.
To accomplish this we must pass the SurfaceKey to OnSurfaceDiscarded.
The SurfaceCache can hold the first frame of a "static" decode as well as the animated frames in two seperate entries. We only care about what happens to the animated frames, so ignore OnSurfaceDiscarded for anything else.
To accomplish this we must pass the SurfaceKey to OnSurfaceDiscarded.
The pref has never been enabled, so this is quite surprising!
It is currently possible (and has been for quite a while) to discard animated images. All we need is the follow sequence of events.
1. Decode an animated image.
2. Move the animated image out of view (so it is not painted).
3. Call canvas.drawImage on the animated image (or anything else that asks for a first frame only decode). This creates a static entry in the surface cache for this first frame in addition to the animated entry. Because it is a static request we will also start a first frame decode. RasterImage::Decode calls SurfaceCache::UnlockEntries
https://dxr.mozilla.org/mozilla-central/rev/4ceb9062ea8f4113bfd1b3536ace4a840a72faa7/image/RasterImage.cpp#1166
and bam, the animated frames are now unlocked (even though the RasterImage, and it's entry in the surface cache is still locked).
4. Switch tabs, open about:memory and minimize memory to actual throw away the animated frames.
5. Switch back to the image tab, scroll the image back into view, it will not animate, it will just show the last composited frame forever.
This patch removes checking of all the callback calls in memory reporter
CollectReport() functions, because it's not useful.
The patch also does some associated clean-up.
- Replaces some uses of nsIMemoryReporterCallback with the preferred
nsIHandleReportCallback typedef.
- Replaces aCallback/aCb/aClosure with aHandleRepor/aData for CollectReports()
parameter names, for consistency.
- Adds MOZ_MUST_USE/[must_use] in a few places in nsIMemoryReporter.idl.
- Uses the MOZ_COLLECT_REPORT macro in all suitable places.
Overall the patch reduces code size by ~300 lines and reduces the size of
libxul by about 37 KiB on my Linux64 builds.
--HG--
extra : rebase_source : e94323614bd10463a0c5134a7276238a7ca1cf23
This means that in RasterImage::LookupFrame when we are asked to do a sync decode (if needed) we use WaitUntilComplete to wait until the frame is finished decoding. But we would actually return after the next progressive pass notified the monitor to wake up. Thus, we would draw a not-fully-decoded image even though the sync decode flag was passed.
The change in FrameAnimator means that we won't draw the next frame in an animated image until all progressive passes of that image are complete. This seems like what we want anyways.
There is one real use of IsImageComplete left, in imgFrame::Draw, where we need to know if the decoded image data covers the whole image frame. (There are a couple of uses of IsImageComplete in asserts.)
http://hg.mozilla.org/mozilla-central/rev/411f18fdffeb (bug 1186796) had a mistake in it.
It changed ImageSurfaceCache::LookupBestMatch to use a for loop instead of using a callback to iterate each entry of the hashtable. The callback was called with the surface key of its entry, and it used the name |aSurfaceKey| for that key. ImageSurfaceCache::LookupBestMatch uses the name |aSurfaceKey| for the key we are looking for. So when the code from the callback was moved into the for loop in ImageSurfaceCache::LookupBestMatch the meaning of |aSurfaceKey| changed, but the code was not updated.
