Oilpan: Use weak pointers in StyleSheetContents caches.

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index f59a38e203d880478af6b41ac56e4eeaad749b46..d6052c671d9917cb8d7efa393386175e331e7955 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -54,18 +54,28 @@ namespace WebCore {
 
 using namespace HTMLNames;
 
-static HashMap<AtomicString, StyleSheetContents*>& textToSheetCache()
+static WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> >& textToSheetCache()

[zerny-chromium, 2014/03/04 13:59:46]

Nit: use the typedef here too.

[Mads Ager (chromium), 2014/03/04 14:03:33]

The typedefs are local to the methods. And typedefs have proven to be a little
dangerous for us in the transition period because it is no longer completely
clear that there is something garbage collected going on. So I'd prefer not to.

 {
-    typedef HashMap<AtomicString, StyleSheetContents*> TextToSheetCache;
+    typedef WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> > TextToSheetCache;
+#if ENABLE(OILPAN)
+    DEFINE_STATIC_LOCAL(Persistent<TextToSheetCache>, cache, (new TextToSheetCache));

[Erik Corry, 2014/03/04 14:09:27]

I think in another change we could use WillBePersistentHeapHashMap which avoids
the cache vs. *cache difference.

[Mads Ager (chromium), 2014/03/04 14:13:36]

Yeah, it would be nice if we could do that. Let's get this in and try to do that
for the 4 or 5 places where we use this pattern now.

+    return *cache;
+#else
     DEFINE_STATIC_LOCAL(TextToSheetCache, cache, ());
     return cache;
+#endif
 }
 
-static HashMap<StyleSheetContents*, AtomicString>& sheetToTextCache()
+static WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString>& sheetToTextCache()

[zerny-chromium, 2014/03/04 13:59:46]

nit: ditto.

 {
-    typedef HashMap<StyleSheetContents*, AtomicString> SheetToTextCache;
+    typedef WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString> SheetToTextCache;
+#if ENABLE(OILPAN)
+    DEFINE_STATIC_LOCAL(Persistent<SheetToTextCache>, cache, (new SheetToTextCache));
+    return *cache;
+#else
     DEFINE_STATIC_LOCAL(SheetToTextCache, cache, ());
     return cache;
+#endif
 }
 
 StyleEngine::StyleEngine(Document& document)
@@ -579,7 +589,7 @@ PassRefPtr<CSSStyleSheet> StyleEngine::createSheet(Element* e, const String& tex
     if (!e->document().inQuirksMode()) {
         AtomicString textContent(text);
 
-        HashMap<AtomicString, StyleSheetContents*>::AddResult result = textToSheetCache().add(textContent, 0);
+        WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> >::AddResult result = textToSheetCache().add(textContent, nullptr);
         if (result.isNewEntry || !result.storedValue->value) {
             styleSheet = StyleEngine::parseSheet(e, text, startPosition, createdByParser);
             if (result.isNewEntry && styleSheet->contents()->maybeCacheable()) {
@@ -610,7 +620,7 @@ PassRefPtr<CSSStyleSheet> StyleEngine::parseSheet(Element* e, const String& text
 
 void StyleEngine::removeSheet(StyleSheetContents* contents)
 {
-    HashMap<StyleSheetContents*, AtomicString>::iterator it = sheetToTextCache().find(contents);
+    WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString>::iterator it = sheetToTextCache().find(contents);
     if (it == sheetToTextCache().end())
         return;