Bug 1693541 - Improve uses of nsBaseHashtable and descendants and avoid multiple subsequent lookups in dom/base. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D106105

dom/base/Document.cpp

@@ -812,22 +812,27 @@ Document* ExternalResourceMap::RequestResource(
     return resource->mDocument;
   }
 
-  RefPtr<PendingLoad>& loadEntry = mPendingLoads.LookupOrInsert(clone);
-  if (loadEntry) {
-    RefPtr<PendingLoad> load(loadEntry);
-    load.forget(aPendingLoad);
-    return nullptr;
-  }
+  bool loadStartSucceeded =
+      mPendingLoads.WithEntryHandle(clone, [&](auto&& loadEntry) {
+        if (!loadEntry) {
+          loadEntry.Insert(MakeRefPtr<PendingLoad>(aDisplayDocument));
 
-  RefPtr<PendingLoad> load(new PendingLoad(aDisplayDocument));
-  loadEntry = load;
+          if (NS_FAILED(loadEntry.Data()->StartLoad(clone, aReferrerInfo,
+                                                    aRequestingNode))) {
+            return false;
+          }
+        }
 
-  if (NS_FAILED(load->StartLoad(clone, aReferrerInfo, aRequestingNode))) {
+        RefPtr<PendingLoad> load(loadEntry.Data());
+        load.forget(aPendingLoad);
+        return true;
+      });
+  if (!loadStartSucceeded) {
     // Make sure we don't thrash things by trying this load again, since
     // chances are it failed for good reasons (security check, etc).
+    // This must be done outside the WithEntryHandle functor, as it accesses
+    // mPendingLoads.
     AddExternalResource(clone, nullptr, nullptr, aDisplayDocument);
-  } else {
-    load.forget(aPendingLoad);
   }
 
   return nullptr;

dom/base/MimeType.cpp

@@ -235,10 +235,12 @@ TMimeType<char_type>::Parse(const nsTSubstring<char_type>& aMimeType) {
 
     // Step 11.10
     if (!paramName.IsEmpty() && !paramNameHadInvalidChars &&
-        !paramValueHadInvalidChars &&
-        !mimeType->mParameters.Get(paramName, &paramValue)) {
-      mimeType->mParameters.InsertOrUpdate(paramName, paramValue);
-      mimeType->mParameterNames.AppendElement(paramName);
+        !paramValueHadInvalidChars) {
+      // XXX Is the assigned value used anywhere?
+      paramValue = mimeType->mParameters.LookupOrInsertWith(paramName, [&] {
+        mimeType->mParameterNames.AppendElement(paramName);
+        return paramValue;
+      });
     }
   }
 
@@ -309,12 +311,14 @@ template <typename char_type>
 void TMimeType<char_type>::SetParameterValue(
     const nsTSubstring<char_type>& aName,
     const nsTSubstring<char_type>& aValue) {
-  if (!mParameters.Get(aName, nullptr)) {
-    mParameterNames.AppendElement(aName);
-  }
-  ParameterValue value;
-  value.Append(aValue);
-  mParameters.InsertOrUpdate(aName, value);
+  mParameters.WithEntryHandle(aName, [&](auto&& entry) {
+    if (!entry) {
+      mParameterNames.AppendElement(aName);
+    }
+    ParameterValue value;
+    value.Append(aValue);
+    entry.InsertOrUpdate(std::move(value));
+  });
 }
 
 template mozilla::UniquePtr<TMimeType<char16_t>> TMimeType<char16_t>::Parse(

dom/base/nsContentUtils.cpp

@@ -964,7 +964,7 @@ bool nsContentUtils::InitializeEventTable() {
 
   // Subtract one from the length because of the trailing null
   for (uint32_t i = 0; i < ArrayLength(eventArray) - 1; ++i) {
-    MOZ_ASSERT(!sAtomEventTable->Lookup(eventArray[i].mAtom),
+    MOZ_ASSERT(!sAtomEventTable->Contains(eventArray[i].mAtom),
                "Double-defining event name; fix your EventNameList.h");
     sAtomEventTable->InsertOrUpdate(eventArray[i].mAtom, eventArray[i]);
     if (ShouldAddEventToStringEventTable(eventArray[i])) {

dom/base/nsFrameMessageManager.cpp

@@ -1005,9 +1005,9 @@ void MessageManagerReporter::CountReferents(
     }
 
     nsString key(it.Key());
-    const uint32_t oldCount = aReferentCount->mMessageCounter.Get(key);
-    uint32_t currentCount = oldCount + listenerCount;
-    aReferentCount->mMessageCounter.InsertOrUpdate(key, currentCount);
+    const uint32_t currentCount =
+        (aReferentCount->mMessageCounter.LookupOrInsert(key, 0) +=
+         listenerCount);
 
     // Keep track of messages that have a suspiciously large
     // number of referents (symptom of leak).

dom/base/nsGlobalWindowInner.cpp

@@ -1007,7 +1007,7 @@ nsGlobalWindowInner::nsGlobalWindowInner(nsGlobalWindowOuter* aOuterWindow,
 
   // Add ourselves to the inner windows list.
   MOZ_ASSERT(sInnerWindowsById, "Inner Windows hash table must be created!");
-  MOZ_ASSERT(!sInnerWindowsById->Get(mWindowID),
+  MOZ_ASSERT(!sInnerWindowsById->Contains(mWindowID),
              "This window shouldn't be in the hash table yet!");
   // We seem to see crashes in release builds because of null
   // |sInnerWindowsById|.

dom/base/nsGlobalWindowOuter.cpp

@@ -1371,7 +1371,7 @@ nsGlobalWindowOuter::nsGlobalWindowOuter(uint64_t aWindowID)
   MOZ_ASSERT(sOuterWindowsById, "Outer Windows hash table must be created!");
 
   // |this| is an outer window, add to the outer windows list.
-  MOZ_ASSERT(!sOuterWindowsById->Get(mWindowID),
+  MOZ_ASSERT(!sOuterWindowsById->Contains(mWindowID),
              "This window shouldn't be in the hash table yet!");
   // We seem to see crashes in release builds because of null
   // |sOuterWindowsById|.