Changeset 53371 in webkit for trunk/JavaScriptCore/runtime/JSString.h

Timestamp:

Jan 16, 2010, 11:18:38 PM (15 years ago)

Author:

[email protected]

Message:

2010-01-16 Maciej Stachowiak <​[email protected]>

Reviewed by Oliver Hunt.

Cache JS string values made from DOM strings (Dromaeo speedup)
​https://bugs.webkit.org/show_bug.cgi?id=33768
<rdar://problem/7353576>

• runtime/JSString.h: (JSC::jsStringWithFinalizer): Added new mechanism for a string to have an optional finalizer callback, for the benefit of weak-referencing caches. (JSC::): (JSC::Fiber::JSString): (JSC::Fiber::~JSString):
• runtime/JSString.cpp: (JSC::JSString::resolveRope): Clear fibers so this doesn't look like a string with a finalizer.
• runtime/WeakGCMap.h: Include "Collector.h" to make this header includable by itself.

2010-01-16 Maciej Stachowiak <​[email protected]>

Reviewed by Oliver Hunt.

Cache JS string values made from DOM strings (Dromaeo speedup)
​https://bugs.webkit.org/show_bug.cgi?id=33768
<rdar://problem/7353576>

• Plugins/Hosted/ProxyInstance.mm: (WebKit::ProxyInstance::stringValue): Explicitly make a String, since char* is now ambiguous.

2010-01-16 Maciej Stachowiak <​[email protected]>

Reviewed by Oliver Hunt.

Cache JS string values made from DOM strings (Dromaeo speedup)
​https://bugs.webkit.org/show_bug.cgi?id=33768
<rdar://problem/7353576>

Added a new cache for JSString values that are created from Strings or AtomicStrings
in the DOM. It's common for the same string to be retrieved from the DOM repeatedly,
and it is wasteful to make a new JS-level string value every time.

The string cache is per-world, and thus thread-safe and not a
vector for accidental information exchange.

~30% speedup on Dromaeo Attributes test, also substantially helps other Dromaeo DOM tests.

• bindings/js/JSDOMBinding.cpp: (WebCore::jsStringCache): Helper function to get the string cache for the current world. (WebCore::jsString): Some new overloads including the caching version. (WebCore::stringWrapperDestroyed): Finalizer callback - remove from relevant caches.
• bindings/js/JSDOMBinding.h: (WebCore::jsString): Prototype new overloads (and define a few inline).
• bindings/js/JSJavaScriptCallFrameCustom.cpp: (WebCore::JSJavaScriptCallFrame::type): Explicitly make a UString.
• bindings/js/ScriptFunctionCall.cpp: (WebCore::ScriptFunctionCall::appendArgument): Ditto.
• WebCore.base.exp: Add new JSString overloads that WebCore gets to see.

File:

• trunk/JavaScriptCore/runtime/JSString.h (modified) (7 diffs)

trunk/JavaScriptCore/runtime/JSString.h

@@ -60 +60 @@
     JSString* jsOwnedString(ExecState*, const UString&); 
 
+    typedef void (*JSStringFinalizerCallback)(JSString*, void* context);
+    JSString* jsStringWithFinalizer(ExecState*, const UString&, JSStringFinalizerCallback callback, void* context);
+
     class JS_EXPORTCLASS JSString : public JSCell {
     public:
@@ -72 +75 @@
             class Fiber {
             public:
-                Fiber() {}
+                Fiber() : m_value(0) {}
                 Fiber(UString::Rep* string) : m_value(reinterpret_cast<intptr_t>(string)) {}
                 Fiber(Rope* rope) : m_value(reinterpret_cast<intptr_t>(rope) | 1) {}
+
+                Fiber(void* nonFiber) : m_value(reinterpret_cast<intptr_t>(nonFiber)) {}
 
                 void deref()
@@ -110 +115 @@
                 UString::Rep* string() { return reinterpret_cast<UString::Rep*>(m_value); }
 
+                void* nonFiber() { return reinterpret_cast<void*>(m_value); }
             private:
                 intptr_t m_value;
@@ -246 +252 @@
         }
 
+        JSString(JSGlobalData* globalData, const UString& value, JSStringFinalizerCallback finalizer, void* context)
+            : JSCell(globalData->stringStructure.get())
+            , m_stringLength(value.size())
+            , m_value(value)
+            , m_ropeLength(0)
+        {
+            // nasty hack because we can't union non-POD types
+            m_fibers[0] = reinterpret_cast<void*>(finalizer);
+            m_fibers[1] = context;
+            Heap::heap(this)->reportExtraMemoryCost(value.cost());
+        }
+
         ~JSString()
         {
@@ -251 +269 @@
             for (unsigned i = 0; i < m_ropeLength; ++i)
                 m_fibers[i].deref();
+
+            if (!m_ropeLength && m_fibers[0].nonFiber()) {
+                JSStringFinalizerCallback finalizer = reinterpret_cast<JSStringFinalizerCallback>(m_fibers[0].nonFiber());
+                finalizer(this, m_fibers[1].nonFiber());
+            }
         }
 
@@ -348 +371 @@
         friend JSValue jsString(ExecState* exec, Register* strings, unsigned count);
         friend JSValue jsString(ExecState* exec, JSValue thisValue, const ArgList& args);
+        friend JSString* jsStringWithFinalizer(ExecState*, const UString&, JSStringFinalizerCallback callback, void* context);
     };
 
@@ -420 +444 @@
         }
         return fixupVPtr(globalData, new (globalData) JSString(globalData, s));
+    }
+
+    inline JSString* jsStringWithFinalizer(ExecState* exec, const UString& s, JSStringFinalizerCallback callback, void* context)
+    {
+        ASSERT(s.size() && (s.size() > 1 || s.data()[0] > 0xFF));
+        JSGlobalData* globalData = &exec->globalData();
+        return fixupVPtr(globalData, new (globalData) JSString(globalData, s, callback, context));
     }