1 files changed, 239 insertions, 0 deletions
diff --git a/gfx/thebes/gfxGradientCache.cpp b/gfx/thebes/gfxGradientCache.cpp
new file mode 100644
index 000000000..fa25bd78c
--- /dev/null
+++ b/gfx/thebes/gfxGradientCache.cpp
@@ -0,0 +1,239 @@
+/* -*- 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/. */
+
+#include "mozilla/gfx/2D.h"
+#include "nsTArray.h"
+#include "PLDHashTable.h"
+#include "nsExpirationTracker.h"
+#include "nsClassHashtable.h"
+#include "mozilla/Telemetry.h"
+#include "gfxGradientCache.h"
+#include <time.h>
+
+namespace mozilla {
+namespace gfx {
+
+using namespace mozilla;
+
+struct GradientCacheKey : public PLDHashEntryHdr {
+  typedef const GradientCacheKey& KeyType;
+  typedef const GradientCacheKey* KeyTypePointer;
+  enum { ALLOW_MEMMOVE = true };
+  const nsTArray<GradientStop> mStops;
+  ExtendMode mExtend;
+  BackendType mBackendType;
+
+  GradientCacheKey(const nsTArray<GradientStop>& aStops, ExtendMode aExtend, BackendType aBackendType)
+    : mStops(aStops), mExtend(aExtend), mBackendType(aBackendType)
+  { }
+
+  explicit GradientCacheKey(const GradientCacheKey* aOther)
+    : mStops(aOther->mStops), mExtend(aOther->mExtend), mBackendType(aOther->mBackendType)
+  { }
+
+  union FloatUint32
+  {
+    float    f;
+    uint32_t u;
+  };
+
+  static PLDHashNumber
+  HashKey(const KeyTypePointer aKey)
+  {
+    PLDHashNumber hash = 0;
+    FloatUint32 convert;
+    hash = AddToHash(hash, int(aKey->mBackendType));
+    hash = AddToHash(hash, int(aKey->mExtend));
+    for (uint32_t i = 0; i < aKey->mStops.Length(); i++) {
+      hash = AddToHash(hash, aKey->mStops[i].color.ToABGR());
+      // Use the float bits as hash, except for the cases of 0.0 and -0.0 which both map to 0
+      convert.f = aKey->mStops[i].offset;
+      hash = AddToHash(hash, convert.f ? convert.u : 0);
+    }
+    return hash;
+  }
+
+  bool KeyEquals(KeyTypePointer aKey) const
+  {
+    bool sameStops = true;
+    if (aKey->mStops.Length() != mStops.Length()) {
+      sameStops = false;
+    } else {
+      for (uint32_t i = 0; i < mStops.Length(); i++) {
+        if (mStops[i].color.ToABGR() != aKey->mStops[i].color.ToABGR() ||
+            mStops[i].offset != aKey->mStops[i].offset) {
+          sameStops = false;
+          break;
+        }
+      }
+    }
+
+    return sameStops &&
+           (aKey->mBackendType == mBackendType) &&
+           (aKey->mExtend == mExtend);
+  }
+  static KeyTypePointer KeyToPointer(KeyType aKey)
+  {
+    return &aKey;
+  }
+};
+
+/**
+ * This class is what is cached. It need to be allocated in an object separated
+ * to the cache entry to be able to be tracked by the nsExpirationTracker.
+ * */
+struct GradientCacheData {
+  GradientCacheData(GradientStops* aStops, const GradientCacheKey& aKey)
+    : mStops(aStops),
+      mKey(aKey)
+  {}
+
+  GradientCacheData(const GradientCacheData& aOther)
+    : mStops(aOther.mStops),
+      mKey(aOther.mKey)
+  { }
+
+  nsExpirationState *GetExpirationState() {
+    return &mExpirationState;
+  }
+
+  nsExpirationState mExpirationState;
+  const RefPtr<GradientStops> mStops;
+  GradientCacheKey mKey;
+};
+
+/**
+ * This class implements a cache with no maximum size, that retains the
+ * gfxPatterns used to draw the gradients.
+ *
+ * The key is the nsStyleGradient that defines the gradient, and the size of the
+ * gradient.
+ *
+ * The value is the gfxPattern, and whether or not we perform an optimization
+ * based on the actual gradient property.
+ *
+ * An entry stays in the cache as long as it is used often. As long as a cache
+ * entry is in the cache, all the references it has are guaranteed to be valid:
+ * the nsStyleRect for the key, the gfxPattern for the value.
+ */
+class GradientCache final : public nsExpirationTracker<GradientCacheData,4>
+{
+  public:
+    GradientCache()
+      : nsExpirationTracker<GradientCacheData,4>(MAX_GENERATION_MS,
+                                                 "GradientCache")
+    {
+      srand(time(nullptr));
+      mTimerPeriod = rand() % MAX_GENERATION_MS + 1;
+      Telemetry::Accumulate(Telemetry::GRADIENT_RETENTION_TIME, mTimerPeriod);
+    }
+
+    virtual void NotifyExpired(GradientCacheData* aObject)
+    {
+      // This will free the gfxPattern.
+      RemoveObject(aObject);
+      mHashEntries.Remove(aObject->mKey);
+    }
+
+    GradientCacheData* Lookup(const nsTArray<GradientStop>& aStops, ExtendMode aExtend, BackendType aBackendType)
+    {
+      GradientCacheData* gradient =
+        mHashEntries.Get(GradientCacheKey(aStops, aExtend, aBackendType));
+
+      if (gradient) {
+        MarkUsed(gradient);
+      }
+
+      return gradient;
+    }
+
+    // Returns true if we successfully register the gradient in the cache, false
+    // otherwise.
+    bool RegisterEntry(GradientCacheData* aValue)
+    {
+      nsresult rv = AddObject(aValue);
+      if (NS_FAILED(rv)) {
+        // We are OOM, and we cannot track this object. We don't want stall
+        // entries in the hash table (since the expiration tracker is responsible
+        // for removing the cache entries), so we avoid putting that entry in the
+        // table, which is a good things considering we are short on memory
+        // anyway, we probably don't want to retain things.
+        return false;
+      }
+      mHashEntries.Put(aValue->mKey, aValue);
+      return true;
+    }
+
+  protected:
+    uint32_t mTimerPeriod;
+    static const uint32_t MAX_GENERATION_MS = 10000;
+    /**
+     * FIXME use nsTHashtable to avoid duplicating the GradientCacheKey.
+     * https://bugzilla.mozilla.org/show_bug.cgi?id=761393#c47
+     */
+    nsClassHashtable<GradientCacheKey, GradientCacheData> mHashEntries;
+};
+
+static GradientCache* gGradientCache = nullptr;
+
+GradientStops *
+gfxGradientCache::GetGradientStops(const DrawTarget *aDT, nsTArray<GradientStop>& aStops, ExtendMode aExtend)
+{
+  if (!gGradientCache) {
+    gGradientCache = new GradientCache();
+  }
+  GradientCacheData* cached =
+    gGradientCache->Lookup(aStops, aExtend, aDT->GetBackendType());
+  if (cached && cached->mStops) {
+    if (!cached->mStops->IsValid()) {
+      gGradientCache->NotifyExpired(cached);
+    } else {
+      return cached->mStops;
+    }
+  }
+
+  return nullptr;
+}
+
+already_AddRefed<GradientStops>
+gfxGradientCache::GetOrCreateGradientStops(const DrawTarget *aDT, nsTArray<GradientStop>& aStops, ExtendMode aExtend)
+{
+  if (aDT->IsRecording()) {
+    return aDT->CreateGradientStops(aStops.Elements(), aStops.Length(), aExtend);
+  }
+
+  RefPtr<GradientStops> gs = GetGradientStops(aDT, aStops, aExtend);
+  if (!gs) {
+    gs = aDT->CreateGradientStops(aStops.Elements(), aStops.Length(), aExtend);
+    if (!gs) {
+      return nullptr;
+    }
+    GradientCacheData *cached =
+      new GradientCacheData(gs, GradientCacheKey(aStops, aExtend,
+                                                 aDT->GetBackendType()));
+    if (!gGradientCache->RegisterEntry(cached)) {
+      delete cached;
+    }
+  }
+  return gs.forget();
+}
+
+void
+gfxGradientCache::PurgeAllCaches()
+{
+  if (gGradientCache) {
+    gGradientCache->AgeAllGenerations();
+  }
+}
+
+void
+gfxGradientCache::Shutdown()
+{
+  delete gGradientCache;
+  gGradientCache = nullptr;
+}
+
+} // namespace gfx
+} // namespace mozilla