1 files changed, 285 insertions, 0 deletions
diff --git a/gfx/thebes/gfxGradientCache.cpp b/gfx/thebes/gfxGradientCache.cpp
new file mode 100644
index 0000000000..c2a1682a7d
--- /dev/null
+++ b/gfx/thebes/gfxGradientCache.cpp
@@ -0,0 +1,285 @@
+/* -*- 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 "gfxGradientCache.h"
+
+#include "MainThreadUtils.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/DataMutex.h"
+#include "nsTArray.h"
+#include "PLDHashTable.h"
+#include "nsExpirationTracker.h"
+#include "nsClassHashtable.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 CopyableTArray<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) {}
+
+  GradientCacheKey(GradientCacheKey&& aOther) = default;
+
+  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, GradientCacheKey&& aKey)
+      : mStops(aStops), mKey(std::move(aKey)) {}
+
+  GradientCacheData(GradientCacheData&& aOther) = default;
+
+  nsExpirationState* GetExpirationState() { return &mExpirationState; }
+
+  nsExpirationState mExpirationState;
+  const RefPtr<GradientStops> mStops;
+  GradientCacheKey mKey;
+};
+
+/**
+ * This class implements a cache, that retains the GradientStops used to draw
+ * the gradients.
+ *
+ * An entry stays in the cache as long as it is used often and we don't exceed
+ * the maximum, in which case the most recently used will be kept.
+ */
+class GradientCache;
+using GradientCacheMutex = StaticDataMutex<UniquePtr<GradientCache>>;
+class MOZ_RAII LockedInstance {
+ public:
+  explicit LockedInstance(GradientCacheMutex& aDataMutex)
+      : mAutoLock(aDataMutex.Lock()) {}
+  UniquePtr<GradientCache>& operator->() const& { return mAutoLock.ref(); }
+  UniquePtr<GradientCache>& operator->() const&& = delete;
+  UniquePtr<GradientCache>& operator*() const& { return mAutoLock.ref(); }
+  UniquePtr<GradientCache>& operator*() const&& = delete;
+  explicit operator bool() const { return !!mAutoLock.ref(); }
+
+ private:
+  GradientCacheMutex::AutoLock mAutoLock;
+};
+
+class GradientCache final
+    : public ExpirationTrackerImpl<GradientCacheData, 4, GradientCacheMutex,
+                                   LockedInstance> {
+ public:
+  GradientCache()
+      : ExpirationTrackerImpl<GradientCacheData, 4, GradientCacheMutex,
+                              LockedInstance>(MAX_GENERATION_MS,
+                                              "GradientCache") {}
+  static bool EnsureInstance() {
+    LockedInstance lockedInstance(sInstanceMutex);
+    return EnsureInstanceLocked(lockedInstance);
+  }
+
+  static void DestroyInstance() {
+    LockedInstance lockedInstance(sInstanceMutex);
+    if (lockedInstance) {
+      *lockedInstance = nullptr;
+    }
+  }
+
+  static void AgeAllGenerations() {
+    LockedInstance lockedInstance(sInstanceMutex);
+    if (!lockedInstance) {
+      return;
+    }
+    lockedInstance->AgeAllGenerationsLocked(lockedInstance);
+    lockedInstance->NotifyHandlerEndLocked(lockedInstance);
+  }
+
+  template <typename CreateFunc>
+  static already_AddRefed<GradientStops> LookupOrInsert(
+      const GradientCacheKey& aKey, CreateFunc aCreateFunc) {
+    uint32_t numberOfEntries;
+    RefPtr<GradientStops> stops;
+    {
+      LockedInstance lockedInstance(sInstanceMutex);
+      if (!EnsureInstanceLocked(lockedInstance)) {
+        return aCreateFunc();
+      }
+
+      GradientCacheData* gradientData = lockedInstance->mHashEntries.Get(aKey);
+      if (gradientData) {
+        if (gradientData->mStops && gradientData->mStops->IsValid()) {
+          lockedInstance->MarkUsedLocked(gradientData, lockedInstance);
+          return do_AddRef(gradientData->mStops);
+        }
+
+        lockedInstance->NotifyExpiredLocked(gradientData, lockedInstance);
+        lockedInstance->NotifyHandlerEndLocked(lockedInstance);
+      }
+
+      stops = aCreateFunc();
+      if (!stops) {
+        return nullptr;
+      }
+
+      auto data = MakeUnique<GradientCacheData>(stops, GradientCacheKey(&aKey));
+      nsresult rv = lockedInstance->AddObjectLocked(data.get(), lockedInstance);
+      if (NS_FAILED(rv)) {
+        // We are OOM, and we cannot track this object. We don't want to store
+        // 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 thing considering we are short on
+        // memory anyway, we probably don't want to retain things.
+        return stops.forget();
+      }
+      lockedInstance->mHashEntries.InsertOrUpdate(aKey, std::move(data));
+      numberOfEntries = lockedInstance->mHashEntries.Count();
+    }
+
+    if (numberOfEntries > MAX_ENTRIES) {
+      // We have too many entries force the cache to age a generation.
+      NS_DispatchToMainThread(
+          NS_NewRunnableFunction("GradientCache::OnMaxEntriesBreached", [] {
+            LockedInstance lockedInstance(sInstanceMutex);
+            if (!lockedInstance) {
+              return;
+            }
+            lockedInstance->AgeOneGenerationLocked(lockedInstance);
+            lockedInstance->NotifyHandlerEndLocked(lockedInstance);
+          }));
+    }
+
+    return stops.forget();
+  }
+
+  GradientCacheMutex& GetMutex() final { return sInstanceMutex; }
+
+  void NotifyExpiredLocked(GradientCacheData* aObject,
+                           const LockedInstance& aLockedInstance) final {
+    // Remove the gradient from the tracker.
+    RemoveObjectLocked(aObject, aLockedInstance);
+
+    // If entry exists move the data to mRemovedGradientData because we want to
+    // drop it outside of the lock.
+    Maybe<UniquePtr<GradientCacheData>> gradientData =
+        mHashEntries.Extract(aObject->mKey);
+    if (gradientData.isSome()) {
+      mRemovedGradientData.AppendElement(std::move(*gradientData));
+    }
+  }
+
+  void NotifyHandlerEndLocked(const LockedInstance&) final {
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("GradientCache::DestroyRemovedGradientStops",
+                               [stops = std::move(mRemovedGradientData)] {}));
+  }
+
+ private:
+  static const uint32_t MAX_GENERATION_MS = 10000;
+
+  // On Windows some of the Direct2D objects associated with the gradient stops
+  // can be quite large, so we limit the number of cache entries.
+  static const uint32_t MAX_ENTRIES = 4000;
+  static GradientCacheMutex sInstanceMutex;
+
+  [[nodiscard]] static bool EnsureInstanceLocked(
+      LockedInstance& aLockedInstance) {
+    if (!aLockedInstance) {
+      // GradientCache must be created on the main thread.
+      if (!NS_IsMainThread()) {
+        // This should only happen at shutdown, we fall back to not caching.
+        return false;
+      }
+      *aLockedInstance = MakeUnique<GradientCache>();
+    }
+    return true;
+  }
+
+  /**
+   * FIXME use nsTHashtable to avoid duplicating the GradientCacheKey.
+   * https://bugzilla.mozilla.org/show_bug.cgi?id=761393#c47
+   */
+  nsClassHashtable<GradientCacheKey, GradientCacheData> mHashEntries;
+  nsTArray<UniquePtr<GradientCacheData>> mRemovedGradientData;
+};
+
+GradientCacheMutex GradientCache::sInstanceMutex("GradientCache");
+
+void gfxGradientCache::Init() {
+  MOZ_RELEASE_ASSERT(GradientCache::EnsureInstance(),
+                     "First call must be on main thread.");
+}
+
+already_AddRefed<GradientStops> gfxGradientCache::GetOrCreateGradientStops(
+    const DrawTarget* aDT, nsTArray<GradientStop>& aStops, ExtendMode aExtend) {
+  if (aDT->IsRecording()) {
+    return aDT->CreateGradientStops(aStops.Elements(), aStops.Length(),
+                                    aExtend);
+  }
+
+  return GradientCache::LookupOrInsert(
+      GradientCacheKey(aStops, aExtend, aDT->GetBackendType()),
+      [&]() -> already_AddRefed<GradientStops> {
+        return aDT->CreateGradientStops(aStops.Elements(), aStops.Length(),
+                                        aExtend);
+      });
+}
+
+void gfxGradientCache::PurgeAllCaches() { GradientCache::AgeAllGenerations(); }
+
+void gfxGradientCache::Shutdown() { GradientCache::DestroyInstance(); }
+
+}  // namespace gfx
+}  // namespace mozilla