Bug 1843239, optimize Location.hash, r=peterv,dom-core

Differential Revision: https://phabricator.services.mozilla.com/D183788

docshell/base/BrowsingContext.cpp

@@ -617,6 +617,7 @@ void BrowsingContext::SetDocShell(nsIDocShell* aDocShell) {
   }
 
   RecomputeCanExecuteScripts();
+  ClearCachedValuesOfLocations();
 }
 
 // This class implements a callback that will return the remote window proxy for
@@ -1048,6 +1049,8 @@ void BrowsingContext::PrepareForProcessChange() {
   mIsInProcess = false;
   mUserGestureStart = TimeStamp();
 
+  ClearCachedValuesOfLocations();
+
   // NOTE: For now, clear our nsDocShell reference, as we're primarily in a
   // different process now. This may need to change in the future with
   // Cross-Process BFCache.
@@ -1414,6 +1417,9 @@ BrowsingContext::~BrowsingContext() {
     sBrowsingContexts->Remove(Id());
   }
   UnregisterBrowserId(this);
+
+  ClearCachedValuesOfLocations();
+  mLocations.clear();
 }
 
 /* static */
@@ -3758,6 +3764,17 @@ void BrowsingContext::ResetLocationChangeRateLimit() {
   mLocationChangeRateLimitSpanStart = TimeStamp();
 }
 
+void BrowsingContext::LocationCreated(dom::Location* aLocation) {
+  MOZ_ASSERT(!aLocation->isInList());
+  mLocations.insertBack(aLocation);
+}
+
+void BrowsingContext::ClearCachedValuesOfLocations() {
+  for (dom::Location* loc = mLocations.getFirst(); loc; loc = loc->getNext()) {
+    loc->ClearCachedValues();
+  }
+}
+
 }  // namespace dom
 
 namespace ipc {

docshell/base/BrowsingContext.h

@@ -68,6 +68,7 @@ class ChildSHistory;
 class ContentParent;
 class Element;
 struct LoadingSessionHistoryInfo;
+class Location;
 template <typename>
 struct Nullable;
 template <typename T>
@@ -948,6 +949,9 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
     return GetIsUnderHiddenEmbedderElement();
   }
 
+  void LocationCreated(dom::Location* aLocation);
+  void ClearCachedValuesOfLocations();
+
  protected:
   virtual ~BrowsingContext();
   BrowsingContext(WindowContext* aParentWindow, BrowsingContextGroup* aGroup,
@@ -1023,7 +1027,7 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
           uintptr_t(this) - offsetof(BrowsingContext, mLocation));
     }
 
-    already_AddRefed<nsIDocShell> GetDocShell() override { return nullptr; }
+    nsIDocShell* GetDocShell() override { return nullptr; }
   };
 
   // Send a given `BaseTransaction` object to the correct remote.
@@ -1406,6 +1410,8 @@ class BrowsingContext : public nsILoadContext, public nsWrapperCache {
   // Used by CheckLocationChangeRateLimit. Do not apply cross-process.
   uint32_t mLocationChangeRateLimitCount;
   mozilla::TimeStamp mLocationChangeRateLimitSpanStart;
+
+  mozilla::LinkedList<dom::Location> mLocations;
 };
 
 /**

docshell/base/nsDocShell.cpp

@@ -1550,7 +1550,7 @@ bool nsDocShell::SetCurrentURI(nsIURI* aURI, nsIRequest* aRequest,
     mTitleValidForCurrentURI = false;
   }
 
-  mCurrentURI = aURI;
+  SetCurrentURIInternal(aURI);
 
 #ifdef DEBUG
   mLastOpenedURI = aURI;
@@ -1576,6 +1576,13 @@ bool nsDocShell::SetCurrentURI(nsIURI* aURI, nsIRequest* aRequest,
   return !aFireOnLocationChange;
 }
 
+void nsDocShell::SetCurrentURIInternal(nsIURI* aURI) {
+  mCurrentURI = aURI;
+  if (mBrowsingContext) {
+    mBrowsingContext->ClearCachedValuesOfLocations();
+  }
+}
+
 NS_IMETHODIMP
 nsDocShell::GetCharset(nsACString& aCharset) {
   aCharset.Truncate();
@@ -4574,7 +4581,7 @@ nsDocShell::Destroy() {
   nsDocLoader::Destroy();
 
   mParentWidget = nullptr;
-  mCurrentURI = nullptr;
+  SetCurrentURIInternal(nullptr);
 
   if (mScriptGlobal) {
     mScriptGlobal->DetachFromDocShell(!mWillChangeProcess);
@@ -8189,7 +8196,7 @@ nsresult nsDocShell::SetupNewViewer(nsIContentViewer* aNewViewer,
     viewer->Close(nullptr);
     viewer->Destroy();
     mContentViewer = nullptr;
-    mCurrentURI = nullptr;
+    SetCurrentURIInternal(nullptr);
     NS_WARNING("ContentViewer Initialization failed");
     return NS_ERROR_FAILURE;
   }

docshell/base/nsDocShell.h

@@ -1160,7 +1160,10 @@ class nsDocShell final : public nsDocLoader,
                                const nsAString& aTitle, bool aReplace,
                                nsIURI* aCurrentURI, bool aEqualURIs);
 
- private:  // data members
+ private:
+  void SetCurrentURIInternal(nsIURI* aURI);
+
+  // data members
   nsString mTitle;
   nsCString mOriginalUriString;
   nsTObserverArray<nsWeakPtr> mPrivacyObservers;
@@ -1205,6 +1208,7 @@ class nsDocShell final : public nsDocLoader,
   mozilla::UniquePtr<mozilla::ObservedDocShell> mObserved;
 
   // mCurrentURI should be marked immutable on set if possible.
+  // Change mCurrentURI only through SetCurrentURIInternal method.
   nsCOMPtr<nsIURI> mCurrentURI;
   nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
 

dom/base/Location.cpp

@@ -23,6 +23,7 @@
 #include "nsContentUtils.h"
 #include "nsDocShell.h"
 #include "nsGlobalWindowOuter.h"
+#include "nsPIDOMWindowInlines.h"
 #include "mozilla/Likely.h"
 #include "nsCycleCollectionParticipant.h"
 #include "mozilla/BasePrincipal.h"
@@ -39,16 +40,19 @@
 
 namespace mozilla::dom {
 
-Location::Location(nsPIDOMWindowInner* aWindow,
-                   BrowsingContext* aBrowsingContext)
-    : mInnerWindow(aWindow) {
-  // aBrowsingContext can be null if it gets called after nsDocShell::Destory().
-  if (aBrowsingContext) {
-    mBrowsingContextId = aBrowsingContext->Id();
+Location::Location(nsPIDOMWindowInner* aWindow)
+    : mCachedHash(VoidString()), mInnerWindow(aWindow) {
+  BrowsingContext* bc = GetBrowsingContext();
+  if (bc) {
+    bc->LocationCreated(this);
   }
 }
 
-Location::~Location() = default;
+Location::~Location() {
+  if (isInList()) {
+    remove();
+  }
+}
 
 // QueryInterface implementation for Location
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Location)
@@ -62,13 +66,12 @@ NS_IMPL_CYCLE_COLLECTING_ADDREF(Location)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(Location)
 
 BrowsingContext* Location::GetBrowsingContext() {
-  RefPtr<BrowsingContext> bc = BrowsingContext::Get(mBrowsingContextId);
-  return bc.get();
+  return mInnerWindow ? mInnerWindow->GetBrowsingContext() : nullptr;
 }
 
-already_AddRefed<nsIDocShell> Location::GetDocShell() {
-  if (RefPtr<BrowsingContext> bc = GetBrowsingContext()) {
-    return do_AddRef(bc->GetDocShell());
+nsIDocShell* Location::GetDocShell() {
+  if (BrowsingContext* bc = GetBrowsingContext()) {
+    return bc->GetDocShell();
   }
   return nullptr;
 }
@@ -76,7 +79,7 @@ already_AddRefed<nsIDocShell> Location::GetDocShell() {
 nsresult Location::GetURI(nsIURI** aURI, bool aGetInnermostURI) {
   *aURI = nullptr;
 
-  nsCOMPtr<nsIDocShell> docShell(GetDocShell());
+  nsIDocShell* docShell = GetDocShell();
   if (!docShell) {
     return NS_OK;
   }
@@ -114,6 +117,11 @@ void Location::GetHash(nsAString& aHash, nsIPrincipal& aSubjectPrincipal,
     return;
   }
 
+  if (!mCachedHash.IsVoid()) {
+    aHash = mCachedHash;
+    return;
+  }
+
   aHash.SetLength(0);
 
   nsCOMPtr<nsIURI> uri;
@@ -123,7 +131,6 @@ void Location::GetHash(nsAString& aHash, nsIPrincipal& aSubjectPrincipal,
   }
 
   nsAutoCString ref;
-  nsAutoString unicodeRef;
 
   aRv = uri->GetRef(ref);
   if (NS_WARN_IF(aRv.Failed())) {
@@ -135,14 +142,7 @@ void Location::GetHash(nsAString& aHash, nsIPrincipal& aSubjectPrincipal,
     AppendUTF8toUTF16(ref, aHash);
   }
 
-  if (aHash == mCachedHash) {
-    // Work around ShareThis stupidly polling location.hash every
-    // 5ms all the time by handing out the same exact string buffer
-    // we handed out last time.
-    aHash = mCachedHash;
-  } else {
-    mCachedHash = aHash;
-  }
+  mCachedHash = aHash;
 }
 
 void Location::SetHash(const nsAString& aHash, nsIPrincipal& aSubjectPrincipal,
@@ -544,7 +544,7 @@ void Location::Reload(bool aForceget, nsIPrincipal& aSubjectPrincipal,
     return;
   }
 
-  RefPtr<nsDocShell> docShell(GetDocShell().downcast<nsDocShell>());
+  RefPtr<nsDocShell> docShell(nsDocShell::Cast(GetDocShell()));
   if (!docShell) {
     return aRv.Throw(NS_ERROR_FAILURE);
   }
@@ -613,7 +613,7 @@ void Location::Assign(const nsAString& aUrl, nsIPrincipal& aSubjectPrincipal,
 bool Location::CallerSubsumes(nsIPrincipal* aSubjectPrincipal) {
   MOZ_ASSERT(aSubjectPrincipal);
 
-  RefPtr<BrowsingContext> bc(GetBrowsingContext());
+  BrowsingContext* bc = GetBrowsingContext();
   if (MOZ_UNLIKELY(!bc) || MOZ_UNLIKELY(bc->IsDiscarded())) {
     // Per spec, operations on a Location object with a discarded BC are no-ops,
     // not security errors, so we need to return true from the access check and
@@ -646,4 +646,6 @@ JSObject* Location::WrapObject(JSContext* aCx,
   return Location_Binding::Wrap(aCx, this, aGivenProto);
 }
 
+void Location::ClearCachedValues() { mCachedHash = VoidString(); }
+
 }  // namespace mozilla::dom

dom/base/Location.h

@@ -9,6 +9,7 @@
 
 #include "js/TypeDecls.h"
 #include "mozilla/ErrorResult.h"
+#include "mozilla/LinkedList.h"
 #include "mozilla/dom/BrowsingContext.h"
 #include "mozilla/dom/LocationBase.h"
 #include "nsCycleCollectionParticipant.h"
@@ -28,11 +29,12 @@ namespace mozilla::dom {
 
 class Location final : public nsISupports,
                        public LocationBase,
-                       public nsWrapperCache {
+                       public nsWrapperCache,
+                       public LinkedListElement<Location> {
  public:
   typedef BrowsingContext::LocationProxy RemoteProxy;
 
-  Location(nsPIDOMWindowInner* aWindow, BrowsingContext* aBrowsingContext);
+  explicit Location(nsPIDOMWindowInner* aWindow);
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(Location)
@@ -110,11 +112,13 @@ class Location final : public nsISupports,
 
   nsresult ToString(nsAString& aString) { return GetHref(aString); }
 
+  void ClearCachedValues();
+
  protected:
   virtual ~Location();
 
   BrowsingContext* GetBrowsingContext() override;
-  already_AddRefed<nsIDocShell> GetDocShell() override;
+  nsIDocShell* GetDocShell() override;
 
   // In the case of jar: uris, we sometimes want the place the jar was
   // fetched from as the URI instead of the jar: uri itself.  Pass in
@@ -127,7 +131,6 @@ class Location final : public nsISupports,
 
   nsString mCachedHash;
   nsCOMPtr<nsPIDOMWindowInner> mInnerWindow;
-  uint64_t mBrowsingContextId = 0;
 };
 
 }  // namespace mozilla::dom

dom/base/LocationBase.h

@@ -36,7 +36,7 @@ class LocationBase {
 
  protected:
   virtual BrowsingContext* GetBrowsingContext() = 0;
-  virtual already_AddRefed<nsIDocShell> GetDocShell() = 0;
+  virtual nsIDocShell* GetDocShell() = 0;
 
   void SetURI(nsIURI* aURL, nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv,
               bool aReplace = false);

dom/base/nsGlobalWindowInner.cpp

@@ -4259,7 +4259,7 @@ nsGlobalWindowInner::GetExistingDebuggerNotificationManager() {
 
 Location* nsGlobalWindowInner::Location() {
   if (!mLocation) {
-    mLocation = new dom::Location(this, GetBrowsingContext());
+    mLocation = new dom::Location(this);
   }
 
   return mLocation;