Add m-esr52 at 52.6.0

1 files changed, 427 insertions, 0 deletions

diff --git a/image/SurfaceCache.h b/image/SurfaceCache.h
new file mode 100644
index 0000000000..e0c22c999c
--- /dev/null
+++ b/image/SurfaceCache.h
@@ -0,0 +1,427 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * SurfaceCache is a service for caching temporary surfaces and decoded image
+ * data in imagelib.
+ */
+
+#ifndef mozilla_image_SurfaceCache_h
+#define mozilla_image_SurfaceCache_h
+
+#include "mozilla/Maybe.h"           // for Maybe
+#include "mozilla/NotNull.h"
+#include "mozilla/MemoryReporting.h" // for MallocSizeOf
+#include "mozilla/HashFunctions.h"   // for HashGeneric and AddToHash
+#include "gfx2DGlue.h"
+#include "gfxPoint.h"                // for gfxSize
+#include "nsCOMPtr.h"                // for already_AddRefed
+#include "mozilla/gfx/Point.h"       // for mozilla::gfx::IntSize
+#include "mozilla/gfx/2D.h"          // for SourceSurface
+#include "PlaybackType.h"
+#include "SurfaceFlags.h"
+#include "SVGImageContext.h"         // for SVGImageContext
+
+namespace mozilla {
+namespace image {
+
+class Image;
+class ISurfaceProvider;
+class LookupResult;
+class SurfaceCacheImpl;
+struct SurfaceMemoryCounter;
+
+/*
+ * ImageKey contains the information we need to look up all SurfaceCache entries
+ * for a particular image.
+ */
+typedef Image* ImageKey;
+
+/*
+ * SurfaceKey contains the information we need to look up a specific
+ * SurfaceCache entry. Together with an ImageKey, this uniquely identifies the
+ * surface.
+ *
+ * Callers should construct a SurfaceKey using the appropriate helper function
+ * for their image type - either RasterSurfaceKey or VectorSurfaceKey.
+ */
+class SurfaceKey
+{
+  typedef gfx::IntSize IntSize;
+
+public:
+  bool operator==(const SurfaceKey& aOther) const
+  {
+    return aOther.mSize == mSize &&
+           aOther.mSVGContext == mSVGContext &&
+           aOther.mPlayback == mPlayback &&
+           aOther.mFlags == mFlags;
+  }
+
+  uint32_t Hash() const
+  {
+    uint32_t hash = HashGeneric(mSize.width, mSize.height);
+    hash = AddToHash(hash, mSVGContext.map(HashSIC).valueOr(0));
+    hash = AddToHash(hash, uint8_t(mPlayback), uint32_t(mFlags));
+    return hash;
+  }
+
+  const IntSize& Size() const { return mSize; }
+  Maybe<SVGImageContext> SVGContext() const { return mSVGContext; }
+  PlaybackType Playback() const { return mPlayback; }
+  SurfaceFlags Flags() const { return mFlags; }
+
+private:
+  SurfaceKey(const IntSize& aSize,
+             const Maybe<SVGImageContext>& aSVGContext,
+             PlaybackType aPlayback,
+             SurfaceFlags aFlags)
+    : mSize(aSize)
+    , mSVGContext(aSVGContext)
+    , mPlayback(aPlayback)
+    , mFlags(aFlags)
+  { }
+
+  static uint32_t HashSIC(const SVGImageContext& aSIC) {
+    return aSIC.Hash();
+  }
+
+  friend SurfaceKey RasterSurfaceKey(const IntSize&, SurfaceFlags, PlaybackType);
+  friend SurfaceKey VectorSurfaceKey(const IntSize&,
+                                     const Maybe<SVGImageContext>&);
+
+  IntSize                mSize;
+  Maybe<SVGImageContext> mSVGContext;
+  PlaybackType           mPlayback;
+  SurfaceFlags           mFlags;
+};
+
+inline SurfaceKey
+RasterSurfaceKey(const gfx::IntSize& aSize,
+                 SurfaceFlags aFlags,
+                 PlaybackType aPlayback)
+{
+  return SurfaceKey(aSize, Nothing(), aPlayback, aFlags);
+}
+
+inline SurfaceKey
+VectorSurfaceKey(const gfx::IntSize& aSize,
+                 const Maybe<SVGImageContext>& aSVGContext)
+{
+  // We don't care about aFlags for VectorImage because none of the flags we
+  // have right now influence VectorImage's rendering. If we add a new flag that
+  // *does* affect how a VectorImage renders, we'll have to change this.
+  // Similarly, we don't accept a PlaybackType parameter because we don't
+  // currently cache frames of animated SVG images.
+  return SurfaceKey(aSize, aSVGContext, PlaybackType::eStatic,
+                    DefaultSurfaceFlags());
+}
+
+
+/**
+ * AvailabilityState is used to track whether an ISurfaceProvider has a surface
+ * available or is just a placeholder.
+ *
+ * To ensure that availability changes are atomic (and especially that internal
+ * SurfaceCache code doesn't have to deal with asynchronous availability
+ * changes), an ISurfaceProvider which starts as a placeholder can only reveal
+ * the fact that it now has a surface available via a call to
+ * SurfaceCache::SurfaceAvailable().
+ */
+class AvailabilityState
+{
+public:
+  static AvailabilityState StartAvailable() { return AvailabilityState(true); }
+  static AvailabilityState StartAsPlaceholder() { return AvailabilityState(false); }
+
+  bool IsAvailable() const { return mIsAvailable; }
+  bool IsPlaceholder() const { return !mIsAvailable; }
+
+private:
+  friend class SurfaceCacheImpl;
+
+  explicit AvailabilityState(bool aIsAvailable) : mIsAvailable(aIsAvailable) { }
+
+  void SetAvailable() { mIsAvailable = true; }
+
+  bool mIsAvailable;
+};
+
+enum class InsertOutcome : uint8_t {
+  SUCCESS,                 // Success (but see Insert documentation).
+  FAILURE,                 // Couldn't insert (e.g., for capacity reasons).
+  FAILURE_ALREADY_PRESENT  // A surface with the same key is already present.
+};
+
+/**
+ * SurfaceCache is an ImageLib-global service that allows caching of decoded
+ * image surfaces, temporary surfaces (e.g. for caching rotated or clipped
+ * versions of images), or dynamically generated surfaces (e.g. for animations).
+ * SurfaceCache entries normally expire from the cache automatically if they go
+ * too long without being accessed.
+ *
+ * Because SurfaceCache must support both normal surfaces and dynamically
+ * generated surfaces, it does not actually hold surfaces directly. Instead, it
+ * holds ISurfaceProvider objects which can provide access to a surface when
+ * requested; SurfaceCache doesn't care about the details of how this is
+ * accomplished.
+ *
+ * Sometime it's useful to temporarily prevent entries from expiring from the
+ * cache. This is most often because losing the data could harm the user
+ * experience (for example, we often don't want to allow surfaces that are
+ * currently visible to expire) or because it's not possible to rematerialize
+ * the surface. SurfaceCache supports this through the use of image locking; see
+ * the comments for Insert() and LockImage() for more details.
+ *
+ * Any image which stores surfaces in the SurfaceCache *must* ensure that it
+ * calls RemoveImage() before it is destroyed. See the comments for
+ * RemoveImage() for more details.
+ */
+struct SurfaceCache
+{
+  typedef gfx::IntSize IntSize;
+
+  /**
+   * Initialize static data. Called during imagelib module initialization.
+   */
+  static void Initialize();
+
+  /**
+   * Release static data. Called during imagelib module shutdown.
+   */
+  static void Shutdown();
+
+  /**
+   * Looks up the requested cache entry and returns a drawable reference to its
+   * associated surface.
+   *
+   * If the image associated with the cache entry is locked, then the entry will
+   * be locked before it is returned.
+   *
+   * If a matching ISurfaceProvider was found in the cache, but SurfaceCache
+   * couldn't obtain a surface from it (e.g. because it had stored its surface
+   * in a volatile buffer which was discarded by the OS) then it is
+   * automatically removed from the cache and an empty LookupResult is returned.
+   * Note that this will never happen to ISurfaceProviders associated with a
+   * locked image; SurfaceCache tells such ISurfaceProviders to keep a strong
+   * references to their data internally.
+   *
+   * @param aImageKey       Key data identifying which image the cache entry
+   *                        belongs to.
+   * @param aSurfaceKey     Key data which uniquely identifies the requested
+   *                        cache entry.
+   * @return                a LookupResult which will contain a DrawableSurface
+   *                        if the cache entry was found.
+   */
+  static LookupResult Lookup(const ImageKey    aImageKey,
+                             const SurfaceKey& aSurfaceKey);
+
+  /**
+   * Looks up the best matching cache entry and returns a drawable reference to
+   * its associated surface.
+   *
+   * The result may vary from the requested cache entry only in terms of size.
+   *
+   * @param aImageKey       Key data identifying which image the cache entry
+   *                        belongs to.
+   * @param aSurfaceKey     Key data which uniquely identifies the requested
+   *                        cache entry.
+   * @return                a LookupResult which will contain a DrawableSurface
+   *                        if a cache entry similar to the one the caller
+   *                        requested could be found. Callers can use
+   *                        LookupResult::IsExactMatch() to check whether the
+   *                        returned surface exactly matches @aSurfaceKey.
+   */
+  static LookupResult LookupBestMatch(const ImageKey    aImageKey,
+                                      const SurfaceKey& aSurfaceKey);
+
+  /**
+   * Insert an ISurfaceProvider into the cache. If an entry with the same
+   * ImageKey and SurfaceKey is already in the cache, Insert returns
+   * FAILURE_ALREADY_PRESENT. If a matching placeholder is already present, it
+   * is replaced.
+   *
+   * Cache entries will never expire as long as they remain locked, but if they
+   * become unlocked, they can expire either because the SurfaceCache runs out
+   * of capacity or because they've gone too long without being used.  When it
+   * is first inserted, a cache entry is locked if its associated image is
+   * locked.  When that image is later unlocked, the cache entry becomes
+   * unlocked too. To become locked again at that point, two things must happen:
+   * the image must become locked again (via LockImage()), and the cache entry
+   * must be touched again (via one of the Lookup() functions).
+   *
+   * All of this means that a very particular procedure has to be followed for
+   * cache entries which cannot be rematerialized. First, they must be inserted
+   * *after* the image is locked with LockImage(); if you use the other order,
+   * the cache entry might expire before LockImage() gets called or before the
+   * entry is touched again by Lookup(). Second, the image they are associated
+   * with must never be unlocked.
+   *
+   * If a cache entry cannot be rematerialized, it may be important to know
+   * whether it was inserted into the cache successfully. Insert() returns
+   * FAILURE if it failed to insert the cache entry, which could happen because
+   * of capacity reasons, or because it was already freed by the OS. If the
+   * cache entry isn't associated with a locked image, checking for SUCCESS or
+   * FAILURE is useless: the entry might expire immediately after being
+   * inserted, even though Insert() returned SUCCESS. Thus, many callers do not
+   * need to check the result of Insert() at all.
+   *
+   * @param aProvider    The new cache entry to insert into the cache.
+   * @return SUCCESS if the cache entry was inserted successfully. (But see above
+   *           for more information about when you should check this.)
+   *         FAILURE if the cache entry could not be inserted, e.g. for capacity
+   *           reasons. (But see above for more information about when you
+   *           should check this.)
+   *         FAILURE_ALREADY_PRESENT if an entry with the same ImageKey and
+   *           SurfaceKey already exists in the cache.
+   */
+  static InsertOutcome Insert(NotNull<ISurfaceProvider*> aProvider);
+
+  /**
+   * Mark the cache entry @aProvider as having an available surface. This turns
+   * a placeholder cache entry into a normal cache entry. The cache entry
+   * becomes locked if the associated image is locked; otherwise, it starts in
+   * the unlocked state.
+   *
+   * If the cache entry containing @aProvider has already been evicted from the
+   * surface cache, this function has no effect.
+   *
+   * It's illegal to call this function if @aProvider is not a placeholder; by
+   * definition, non-placeholder ISurfaceProviders should have a surface
+   * available already.
+   *
+   * @param aProvider       The cache entry that now has a surface available.
+   */
+  static void SurfaceAvailable(NotNull<ISurfaceProvider*> aProvider);
+
+  /**
+   * Checks if a surface of a given size could possibly be stored in the cache.
+   * If CanHold() returns false, Insert() will always fail to insert the
+   * surface, but the inverse is not true: Insert() may take more information
+   * into account than just image size when deciding whether to cache the
+   * surface, so Insert() may still fail even if CanHold() returns true.
+   *
+   * Use CanHold() to avoid the need to create a temporary surface when we know
+   * for sure the cache can't hold it.
+   *
+   * @param aSize  The dimensions of a surface in pixels.
+   * @param aBytesPerPixel  How many bytes each pixel of the surface requires.
+   *                        Defaults to 4, which is appropriate for RGBA or RGBX
+   *                        images.
+   *
+   * @return false if the surface cache can't hold a surface of that size.
+   */
+  static bool CanHold(const IntSize& aSize, uint32_t aBytesPerPixel = 4);
+  static bool CanHold(size_t aSize);
+
+  /**
+   * Locks an image. Any of the image's cache entries which are either inserted
+   * or accessed while the image is locked will not expire.
+   *
+   * Locking an image does not automatically lock that image's existing cache
+   * entries. A call to LockImage() guarantees that entries which are inserted
+   * afterward will not expire before the next call to UnlockImage() or
+   * UnlockSurfaces() for that image. Cache entries that are accessed via
+   * Lookup() or LookupBestMatch() after a LockImage() call will also not expire
+   * until the next UnlockImage() or UnlockSurfaces() call for that image. Any
+   * other cache entries owned by the image may expire at any time.
+   *
+   * All of an image's cache entries are removed by RemoveImage(), whether the
+   * image is locked or not.
+   *
+   * It's safe to call LockImage() on an image that's already locked; this has
+   * no effect.
+   *
+   * You must always unlock any image you lock. You may do this explicitly by
+   * calling UnlockImage(), or implicitly by calling RemoveImage(). Since you're
+   * required to call RemoveImage() when you destroy an image, this doesn't
+   * impose any additional requirements, but it's preferable to call
+   * UnlockImage() earlier if it's possible.
+   *
+   * @param aImageKey    The image to lock.
+   */
+  static void LockImage(const ImageKey aImageKey);
+
+  /**
+   * Unlocks an image, allowing any of its cache entries to expire at any time.
+   *
+   * It's OK to call UnlockImage() on an image that's already unlocked; this has
+   * no effect.
+   *
+   * @param aImageKey    The image to unlock.
+   */
+  static void UnlockImage(const ImageKey aImageKey);
+
+  /**
+   * Unlocks the existing cache entries of an image, allowing them to expire at
+   * any time.
+   *
+   * This does not unlock the image itself, so accessing the cache entries via
+   * Lookup() or LookupBestMatch() will lock them again, and prevent them from
+   * expiring.
+   *
+   * This is intended to be used in situations where it's no longer clear that
+   * all of the cache entries owned by an image are needed. Calling
+   * UnlockSurfaces() and then taking some action that will cause Lookup() to
+   * touch any cache entries that are still useful will permit the remaining
+   * entries to expire from the cache.
+   *
+   * If the image is unlocked, this has no effect.
+   *
+   * @param aImageKey    The image which should have its existing cache entries
+   *                     unlocked.
+   */
+  static void UnlockEntries(const ImageKey aImageKey);
+
+  /**
+   * Removes all cache entries (including placeholders) associated with the
+   * given image from the cache.  If the image is locked, it is automatically
+   * unlocked.
+   *
+   * This MUST be called, at a minimum, when an Image which could be storing
+   * entries in the surface cache is destroyed. If another image were allocated
+   * at the same address it could result in subtle, difficult-to-reproduce bugs.
+   *
+   * @param aImageKey  The image which should be removed from the cache.
+   */
+  static void RemoveImage(const ImageKey aImageKey);
+
+  /**
+   * Evicts all evictable entries from the cache.
+   *
+   * All entries are evictable except for entries associated with locked images.
+   * Non-evictable entries can only be removed by RemoveImage().
+   */
+  static void DiscardAll();
+
+  /**
+   * Collects an accounting of the surfaces contained in the SurfaceCache for
+   * the given image, along with their size and various other metadata.
+   *
+   * This is intended for use with memory reporting.
+   *
+   * @param aImageKey     The image to report memory usage for.
+   * @param aCounters     An array into which the report for each surface will
+   *                      be written.
+   * @param aMallocSizeOf A fallback malloc memory reporting function.
+   */
+  static void CollectSizeOfSurfaces(const ImageKey    aImageKey,
+                                    nsTArray<SurfaceMemoryCounter>& aCounters,
+                                    MallocSizeOf      aMallocSizeOf);
+
+  /**
+   * @return maximum capacity of the SurfaceCache in bytes. This is only exposed
+   * for use by tests; normal code should use CanHold() instead.
+   */
+  static size_t MaximumCapacity();
+
+private:
+  virtual ~SurfaceCache() = 0;  // Forbid instantiation.
+};
+
+} // namespace image
+} // namespace mozilla
+
+#endif // mozilla_image_SurfaceCache_h