1 files changed, 150 insertions, 0 deletions
diff --git a/layout/style/RuleProcessorCache.h b/layout/style/RuleProcessorCache.h
new file mode 100644
index 000000000..7eb808fc9
--- /dev/null
+++ b/layout/style/RuleProcessorCache.h
@@ -0,0 +1,150 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+/*
+ * cache of re-usable nsCSSRuleProcessors for given sets of style sheets
+ */
+
+#ifndef mozilla_RuleProcessorCache_h
+#define mozilla_RuleProcessorCache_h
+
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/StaticPtr.h"
+#include "nsCSSRuleProcessor.h"
+#include "nsExpirationTracker.h"
+#include "nsIMediaList.h"
+#include "nsIMemoryReporter.h"
+#include "nsTArray.h"
+
+class nsCSSRuleProcessor;
+namespace mozilla {
+class CSSStyleSheet;
+namespace css {
+class DocumentRule;
+} // namespace css
+} // namespace mozilla
+
+namespace mozilla {
+
+/**
+ * The RuleProcessorCache is a singleton object that caches
+ * nsCSSRuleProcessors keyed off a list of style sheets and the result of
+ * evaluating all @-moz-documents in the style sheets.  nsStyleSet gets and
+ * puts nsCSSRuleProcessors from/to the RuleProcessorCache.
+ *
+ * State bits on CSSStyleSheet and nsCSSRuleProcessor track whether they are in
+ * the RuleProcessorCache.  This lets us remove them from the RuleProcessorCache
+ * when they're going away.
+ */
+class RuleProcessorCache final : public nsIMemoryReporter
+{
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIMEMORYREPORTER
+
+public:
+  static nsCSSRuleProcessor* GetRuleProcessor(
+      const nsTArray<CSSStyleSheet*>& aSheets,
+      nsPresContext* aPresContext);
+  static void PutRuleProcessor(
+      const nsTArray<CSSStyleSheet*>& aSheets,
+      nsTArray<css::DocumentRule*>&& aDocumentRulesInSheets,
+      const nsDocumentRuleResultCacheKey& aCacheKey,
+      nsCSSRuleProcessor* aRuleProcessor);
+  static void StartTracking(nsCSSRuleProcessor* aRuleProcessor);
+  static void StopTracking(nsCSSRuleProcessor* aRuleProcessor);
+
+#ifdef DEBUG
+  static bool HasRuleProcessor(nsCSSRuleProcessor* aRuleProcessor);
+#endif
+  static void RemoveRuleProcessor(nsCSSRuleProcessor* aRuleProcessor);
+  static void RemoveSheet(CSSStyleSheet* aSheet);
+
+  static void Shutdown() { gShutdown = true; gRuleProcessorCache = nullptr; }
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
+
+private:
+  class ExpirationTracker : public nsExpirationTracker<nsCSSRuleProcessor,3>
+  {
+  public:
+    explicit ExpirationTracker(RuleProcessorCache* aCache)
+      : nsExpirationTracker<nsCSSRuleProcessor,3>(
+          10000, "RuleProcessorCache::ExpirationTracker")
+      , mCache(aCache) {}
+
+    void RemoveObjectIfTracked(nsCSSRuleProcessor* aRuleProcessor);
+
+    virtual void NotifyExpired(nsCSSRuleProcessor* aRuleProcessor) override {
+      mCache->RemoveRuleProcessor(aRuleProcessor);
+    }
+
+  private:
+    RuleProcessorCache* mCache;
+  };
+
+  RuleProcessorCache() : mExpirationTracker(this) {}
+  ~RuleProcessorCache();
+
+  void InitMemoryReporter();
+
+  static bool EnsureGlobal();
+  static StaticRefPtr<RuleProcessorCache> gRuleProcessorCache;
+  static bool gShutdown;
+
+  void DoRemoveSheet(CSSStyleSheet* aSheet);
+  nsCSSRuleProcessor* DoGetRuleProcessor(
+      const nsTArray<CSSStyleSheet*>& aSheets,
+      nsPresContext* aPresContext);
+  void DoPutRuleProcessor(const nsTArray<CSSStyleSheet*>& aSheets,
+                          nsTArray<css::DocumentRule*>&& aDocumentRulesInSheets,
+                          const nsDocumentRuleResultCacheKey& aCacheKey,
+                          nsCSSRuleProcessor* aRuleProcessor);
+#ifdef DEBUG
+  bool DoHasRuleProcessor(nsCSSRuleProcessor* aRuleProcessor);
+#endif
+  void DoRemoveRuleProcessor(nsCSSRuleProcessor* aRuleProcessor);
+  void DoStartTracking(nsCSSRuleProcessor* aRuleProcessor);
+  void DoStopTracking(nsCSSRuleProcessor* aRuleProcessor);
+
+  struct DocumentEntry {
+    nsDocumentRuleResultCacheKey mCacheKey;
+    RefPtr<nsCSSRuleProcessor> mRuleProcessor;
+  };
+
+  struct Entry {
+    nsTArray<CSSStyleSheet*>     mSheets;
+    nsTArray<css::DocumentRule*> mDocumentRulesInSheets;
+    nsTArray<DocumentEntry>      mDocumentEntries;
+  };
+
+  // Function object to test whether an Entry object has a given sheet
+  // in its mSheets array.  If it does, removes all of its rule processors
+  // before returning true.
+  struct HasSheet_ThenRemoveRuleProcessors {
+    HasSheet_ThenRemoveRuleProcessors(RuleProcessorCache* aCache,
+                                      CSSStyleSheet* aSheet)
+      : mCache(aCache), mSheet(aSheet) {}
+    bool operator()(Entry& aEntry) {
+      if (aEntry.mSheets.Contains(mSheet)) {
+        for (DocumentEntry& de : aEntry.mDocumentEntries) {
+          de.mRuleProcessor->SetInRuleProcessorCache(false);
+          mCache->mExpirationTracker.RemoveObjectIfTracked(de.mRuleProcessor);
+        }
+        return true;
+      }
+      return false;
+    }
+    RuleProcessorCache* mCache;
+    CSSStyleSheet* mSheet;
+  };
+
+  ExpirationTracker mExpirationTracker;
+  nsTArray<Entry> mEntries;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_RuleProcessorCache_h