Bug 987556 Part 8 Use JS::SourceBufferHolder in XULDocument. r=bz

dothq · Apr 25, 2014 · 80a0d6e · 80a0d6e
1 parent 0ff1f6a
commit 80a0d6e
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Showing 4 changed files with 61 additions and 13 deletions.
diff --git a/content/xul/content/src/nsXULElement.cpp b/content/xul/content/src/nsXULElement.cpp
@@ -2619,8 +2619,7 @@ OffThreadScriptReceiverCallback(void *aToken, void *aCallbackData)
 }
 
 nsresult
-nsXULPrototypeScript::Compile(const char16_t* aText,
-                              int32_t aTextLength,
+nsXULPrototypeScript::Compile(JS::SourceBufferHolder& aSrcBuf,
                               nsIURI* aURI,
                               uint32_t aLineNo,
                               nsIDocument* aDocument,
@@ -2651,25 +2650,38 @@ nsXULPrototypeScript::Compile(const char16_t* aText,
       JS::ExposeObjectToActiveJS(scope);
     }
 
-    if (aOffThreadReceiver && JS::CanCompileOffThread(cx, options, aTextLength)) {
+    if (aOffThreadReceiver && JS::CanCompileOffThread(cx, options, aSrcBuf.length())) {
         if (!JS::CompileOffThread(cx, options,
-                                  static_cast<const jschar*>(aText), aTextLength,
+                                  aSrcBuf.get(), aSrcBuf.length(),
                                   OffThreadScriptReceiverCallback,
                                   static_cast<void*>(aOffThreadReceiver))) {
             return NS_ERROR_OUT_OF_MEMORY;
         }
         // This reference will be consumed by the NotifyOffThreadScriptCompletedRunnable.
         NS_ADDREF(aOffThreadReceiver);
     } else {
-        JSScript* script = JS::Compile(cx, scope, options,
-                                   static_cast<const jschar*>(aText), aTextLength);
+        JSScript* script = JS::Compile(cx, scope, options, aSrcBuf);
         if (!script)
             return NS_ERROR_OUT_OF_MEMORY;
         Set(script);
     }
     return NS_OK;
 }
 
+nsresult
+nsXULPrototypeScript::Compile(const char16_t* aText,
+                              int32_t aTextLength,
+                              nsIURI* aURI,
+                              uint32_t aLineNo,
+                              nsIDocument* aDocument,
+                              nsXULPrototypeDocument* aProtoDoc,
+                              nsIOffThreadScriptReceiver *aOffThreadReceiver /* = nullptr */)
+{
+  JS::SourceBufferHolder srcBuf(aText, aTextLength,
+                                JS::SourceBufferHolder::NoOwnership);
+  return Compile(srcBuf, aURI, aLineNo, aDocument, aProtoDoc, aOffThreadReceiver);
+}
+
 void
 nsXULPrototypeScript::UnlinkJSObjects()
 {

diff --git a/content/xul/content/src/nsXULElement.h b/content/xul/content/src/nsXULElement.h
@@ -56,6 +56,10 @@ class StyleRule;
 }
 }
 
+namespace JS {
+class SourceBufferHolder;
+}
+
 ////////////////////////////////////////////////////////////////////////
 
 #ifdef XUL_PROTOTYPE_ATTRIBUTE_METERING
@@ -231,6 +235,12 @@ class nsXULPrototypeScript : public nsXULPrototypeNode
     nsresult DeserializeOutOfLine(nsIObjectInputStream* aInput,
                                   nsXULPrototypeDocument* aProtoDoc);
 
+    nsresult Compile(JS::SourceBufferHolder& aSrcBuf,
+                     nsIURI* aURI, uint32_t aLineNo,
+                     nsIDocument* aDocument,
+                     nsXULPrototypeDocument* aProtoDoc,
+                     nsIOffThreadScriptReceiver *aOffThreadReceiver = nullptr);
+
     nsresult Compile(const char16_t* aText, int32_t aTextLength,
                      nsIURI* aURI, uint32_t aLineNo,
                      nsIDocument* aDocument,

diff --git a/content/xul/document/src/XULDocument.cpp b/content/xul/document/src/XULDocument.cpp
@@ -245,6 +245,10 @@ XULDocument::~XULDocument()
         NS_IF_RELEASE(kNC_attribute);
         NS_IF_RELEASE(kNC_value);
     }
+
+    if (mOffThreadCompileStringBuf) {
+      js_free(mOffThreadCompileStringBuf);
+    }
 }
 
 } // namespace dom
@@ -3526,14 +3530,26 @@ XULDocument::OnStreamComplete(nsIStreamLoader* aLoader,
 
         // XXX should also check nsIHttpChannel::requestSucceeded
 
-        MOZ_ASSERT(!mOffThreadCompiling && mOffThreadCompileString.Length() == 0,
+        MOZ_ASSERT(!mOffThreadCompiling && (mOffThreadCompileStringLength == 0 &&
+                                            !mOffThreadCompileStringBuf),
                    "XULDocument can't load multiple scripts at once");
 
         rv = nsScriptLoader::ConvertToUTF16(channel, string, stringLen,
-                                            EmptyString(), this, mOffThreadCompileString);
+                                            EmptyString(), this,
+                                            mOffThreadCompileStringBuf,
+                                            mOffThreadCompileStringLength);
         if (NS_SUCCEEDED(rv)) {
-            rv = mCurrentScriptProto->Compile(mOffThreadCompileString.get(),
-                                              mOffThreadCompileString.Length(),
+            // Attempt to give ownership of the buffer to the JS engine.  If
+            // we hit offthread compilation, however, we will have to take it
+            // back below in order to keep the memory alive until compilation
+            // completes.
+            JS::SourceBufferHolder srcBuf(mOffThreadCompileStringBuf,
+                                          mOffThreadCompileStringLength,
+                                          JS::SourceBufferHolder::GiveOwnership);
+            mOffThreadCompileStringBuf = nullptr;
+            mOffThreadCompileStringLength = 0;
+
+            rv = mCurrentScriptProto->Compile(srcBuf,
                                               uri, 1, this,
                                               mCurrentPrototype,
                                               this);
@@ -3542,10 +3558,15 @@ XULDocument::OnStreamComplete(nsIStreamLoader* aLoader,
                 // compile finishes. Keep the contents of the compiled script
                 // alive until the compilation finishes.
                 mOffThreadCompiling = true;
+                // If the JS engine did not take the source buffer, then take
+                // it back here to ensure it remains alive.
+                mOffThreadCompileStringBuf = srcBuf.take();
+                if (mOffThreadCompileStringBuf) {
+                  mOffThreadCompileStringLength = srcBuf.length();
+                }
                 BlockOnload();
                 return NS_OK;
             }
-            mOffThreadCompileString.Truncate();
         }
     }
 
@@ -3567,7 +3588,11 @@ XULDocument::OnScriptCompileComplete(JSScript* aScript, nsresult aStatus)
     }
 
     // After compilation finishes the script's characters are no longer needed.
-    mOffThreadCompileString.Truncate();
+    if (mOffThreadCompileStringBuf) {
+      js_free(mOffThreadCompileStringBuf);
+      mOffThreadCompileStringBuf = nullptr;
+      mOffThreadCompileStringLength = 0;
+    }
 
     // Clear mCurrentScriptProto now, but save it first for use below in
     // the execute code, and in the while loop that resumes walks of other

diff --git a/content/xul/document/src/XULDocument.h b/content/xul/document/src/XULDocument.h
@@ -460,7 +460,8 @@ class XULDocument MOZ_FINAL : public XMLDocument,
      * If the current transcluded script is being compiled off thread, the
      * source for that script.
      */
-    nsString mOffThreadCompileString;
+    jschar* mOffThreadCompileStringBuf;
+    size_t mOffThreadCompileStringLength;
 
     /**
      * Check if a XUL template builder has already been hooked up.