2 files changed, 81 insertions, 8 deletions

diff --git a/dom/fetch/InternalHeaders.cpp b/dom/fetch/InternalHeaders.cpp
index e81863173..11585615e 100644
--- a/dom/fetch/InternalHeaders.cpp
+++ b/dom/fetch/InternalHeaders.cpp
@@ -21,12 +21,14 @@ InternalHeaders::InternalHeaders(const nsTArray<Entry>&& aHeaders,
                                  HeadersGuardEnum aGuard)
   : mGuard(aGuard)
   , mList(aHeaders)
+  , mListDirty(true)
 {
 }
 
 InternalHeaders::InternalHeaders(const nsTArray<HeadersEntry>& aHeadersEntryList,
                                  HeadersGuardEnum aGuard)
   : mGuard(aGuard)
+  , mListDirty(true)
 {
   for (const HeadersEntry& headersEntry : aHeadersEntryList) {
     mList.AppendElement(Entry(headersEntry.name(), headersEntry.value()));
@@ -56,6 +58,8 @@ InternalHeaders::Append(const nsACString& aName, const nsACString& aValue,
     return;
   }
 
+  SetListDirty();
+
   mList.AppendElement(Entry(lowerName, aValue));
 }
 
@@ -69,6 +73,8 @@ InternalHeaders::Delete(const nsACString& aName, ErrorResult& aRv)
     return;
   }
 
+  SetListDirty();
+
   // remove in reverse order to minimize copying
   for (int32_t i = mList.Length() - 1; i >= 0; --i) {
     if (lowerName == mList[i].mName) {
@@ -155,6 +161,8 @@ InternalHeaders::Set(const nsACString& aName, const nsACString& aValue, ErrorRes
     return;
   }
 
+  SetListDirty();
+
   int32_t firstIndex = INT32_MAX;
 
   // remove in reverse order to minimize copying
@@ -177,6 +185,7 @@ InternalHeaders::Set(const nsACString& aName, const nsACString& aValue, ErrorRes
 void
 InternalHeaders::Clear()
 {
+  SetListDirty();
   mList.Clear();
 }
 
@@ -419,5 +428,54 @@ InternalHeaders::GetUnsafeHeaders(nsTArray<nsCString>& aNames) const
   }
 }
 
+void
+InternalHeaders::MaybeSortList()
+{
+  class Comparator {
+  public:
+    bool Equals(const Entry& aA, const Entry& aB) const
+    {
+       return aA.mName == aB.mName;
+    }
+
+    bool LessThan(const Entry& aA, const Entry& aB) const
+    {
+      return aA.mName < aB.mName;
+    }
+  };
+
+  if (!mListDirty) {
+    return;
+  }
+
+  mListDirty = false;
+
+  Comparator comparator;
+
+  mSortedList.Clear();
+  for (const Entry& entry : mList) {
+    bool found = false;
+    for (Entry& sortedEntry : mSortedList) {
+      if (sortedEntry.mName == entry.mName) {
+        sortedEntry.mValue += ", ";
+        sortedEntry.mValue += entry.mValue;
+        found = true;
+        break;
+      }
+    }
+
+    if (!found) {
+      mSortedList.InsertElementSorted(entry, comparator);
+    }
+  }
+}
+
+void
+InternalHeaders::SetListDirty()
+{
+  mSortedList.Clear();
+  mListDirty = true;
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/fetch/InternalHeaders.h b/dom/fetch/InternalHeaders.h
index e47066669..9a6d6dae7 100644
--- a/dom/fetch/InternalHeaders.h
+++ b/dom/fetch/InternalHeaders.h
@@ -45,14 +45,23 @@ private:
   HeadersGuardEnum mGuard;
   nsTArray<Entry> mList;
 
+  nsTArray<Entry> mSortedList;
+
+  // This boolean is set to true at any writing operation to mList. It's set to
+  // false when mSortedList is regenerated. This happens when the header is
+  // iterated.
+  bool mListDirty;
+
 public:
   explicit InternalHeaders(HeadersGuardEnum aGuard = HeadersGuardEnum::None)
     : mGuard(aGuard)
+    , mListDirty(false)
   {
   }
 
   explicit InternalHeaders(const InternalHeaders& aOther)
     : mGuard(HeadersGuardEnum::None)
+    , mListDirty(true)
   {
     ErrorResult result;
     Fill(aOther, result);
@@ -79,19 +88,22 @@ public:
   bool Has(const nsACString& aName, ErrorResult& aRv) const;
   void Set(const nsACString& aName, const nsACString& aValue, ErrorResult& aRv);
 
-  uint32_t GetIterableLength() const
+  uint32_t GetIterableLength()
   {
-    return mList.Length();
+    MaybeSortList();
+    return mSortedList.Length();
   }
-  const NS_ConvertASCIItoUTF16 GetKeyAtIndex(unsigned aIndex) const
+  const NS_ConvertASCIItoUTF16 GetKeyAtIndex(unsigned aIndex)
   {
-    MOZ_ASSERT(aIndex < mList.Length());
-    return NS_ConvertASCIItoUTF16(mList[aIndex].mName);
+    MaybeSortList();
+    MOZ_ASSERT(aIndex < mSortedList.Length());
+    return NS_ConvertASCIItoUTF16(mSortedList[aIndex].mName);
   }
-  const NS_ConvertASCIItoUTF16 GetValueAtIndex(unsigned aIndex) const
+  const NS_ConvertASCIItoUTF16 GetValueAtIndex(unsigned aIndex)
   {
-    MOZ_ASSERT(aIndex < mList.Length());
-    return NS_ConvertASCIItoUTF16(mList[aIndex].mValue);
+    MaybeSortList();
+    MOZ_ASSERT(aIndex < mSortedList.Length());
+    return NS_ConvertASCIItoUTF16(mSortedList[aIndex].mValue);
   }
 
   void Clear();
@@ -152,6 +164,9 @@ private:
                              const nsACString& aValue);
 
   static bool IsRevalidationHeader(const nsACString& aName);
+
+  void MaybeSortList();
+  void SetListDirty();
 };
 
 } // namespace dom