Oilpan: Prepare to move AXObjectCache to the heap

Source/core/dom/AXObjectCache.cpp

Index: Source/core/dom/AXObjectCache.cpp
diff --git a/Source/core/dom/AXObjectCache.cpp b/Source/core/dom/AXObjectCache.cpp
index 340616585a1efceb73bd691051ee2524ed4b56dc..3670a5ad71b109d0fea6b8b390563fab274be923 100644
--- a/Source/core/dom/AXObjectCache.cpp
+++ b/Source/core/dom/AXObjectCache.cpp
@@ -40,7 +40,7 @@ void AXObjectCache::init(AXObjectCacheCreateFunction function)
     m_createFunction = function;
 }
 
-AXObjectCache* AXObjectCache::create(Document& document)
+PassOwnPtrWillBeRawPtr<AXObjectCache> AXObjectCache::create(Document& document)
 {
     ASSERT(m_createFunction);
     return (m_createFunction)(document);
@@ -54,34 +54,31 @@ AXObjectCache::~AXObjectCache()
 {
 }
 
-ScopedAXObjectCache::ScopedAXObjectCache(Document& document)
-    : m_document(document)
-    , m_cache(0)
+PassOwnPtr<ScopedAXObjectCache> ScopedAXObjectCache::create(Document& document)
 {
-    if (AXObjectCache* existingCache = document.axObjectCache()) {
-        m_cache = existingCache;
-        m_isScoped = false;
-    } else {
-        m_isScoped = true;
-        m_cache = AXObjectCache::create(m_document);
-    }
+    return adoptPtr(new ScopedAXObjectCache(document));
 }
 
-ScopedAXObjectCache::~ScopedAXObjectCache()
+ScopedAXObjectCache::ScopedAXObjectCache(Document& document)
+    : m_document(&document)
 {
-    if (m_isScoped)
-        delete m_cache;
+    if (!m_document->axObjectCache())
+        m_cache = AXObjectCache::create(*m_document);

[haraken, 2015/06/08 11:03:13]

A slightly better way would be to create the cache lazily in get(). See the
comment below.

 }
 
-AXObjectCache* ScopedAXObjectCache::get()
+ScopedAXObjectCache::~ScopedAXObjectCache()
 {
-    ASSERT(m_cache);
-    return m_cache;
+    if (m_cache)
+        m_cache->dispose();
 }
 
-AXObjectCache* ScopedAXObjectCache::operator->()
+AXObjectCache* ScopedAXObjectCache::get()
 {
-    return get();
+    if (m_cache)

[haraken, 2015/06/08 11:03:13]

You can do something like:

if (m_document->axObjectCache())
  return m_document->axObjectCache();
if (!m_cache)
  m_cache = AXObjectCache::create(*m_document);
return m_cache.get();

[dmazzoni, 2015/06/08 15:04:06]

Doing this assumes that the accessibility flag doesn't change. Suppose someone
creates a ScopedAXObjectCache, but then enables the accessibility flag before
disposing of it - then a subsequent call to get() would return a different
object.

I don't expect this should happen on purpose, but still I'd prefer that this
code doesn't make assumptions it shouldn't have to.

[haraken, 2015/06/08 23:38:15]

Makes sense -- let's go with the current CL.

+        return m_cache.get();
+    AXObjectCache* cache = m_document->axObjectCache();
+    ASSERT(cache);
+    return cache;
 }
 
 } // namespace blink