webkit加載網頁

一、讀取url





以下內容部分引自http://blog.csdn.net/dlmu2001/article/details/5936122
http的協議細節實現並不需要WebCore來關注，WebCore要關注的是，如何設置請求的相關頭部信息，如何獲取服務器返回回來的響應體部數據。
WebKit中同http打交道的類主要是ResourceRequest，ResourceResonse，ResourceHandle*，ResourceHandleManager等，這裏先介紹同請求信息維護相關的ResourceRequest.
ResourceRequest類的作用比較好理解，基本上就是維護http請求相關的信息（app或者內核都有可能設置這些信息），然後當WebCore發起http請求的時候，可以獲取這些信息，調用curl的接口設置對應的http請求字段。在這些信息中，最常用到的是url。
ResourceRequest類繼承於ResourceRequestBase類，絕大部分功能在ResourceRequestBase類中實現。
一）ResourceRequest構造：構造一個ResourceRequest對象只需要url參數就夠了，這是比較簡單的一個類，沒有維護其它類的對象或者句柄。
ResourceRequest(const String& url)；
ResourceRequest(const KURL& url)；
二）ResourceRequest對象的創建與維護
1.當用戶輸入網址，觸發qt事件，由MainWindow(WebKitBuild/Debug/QtTestBrowser/moc_mainwindow.cpp:87<--moc_launcherwindow.cpp:145)調用changeLocation函數（另有openLocation等）。
由MainWindow(Tools/QtTestBrowser/mainwindow.cpp:194)獲取地址欄中的url(QString類型/usr/include/QtCore/qstring.h)，創建QUrl類型(/usr/include/QtCore/qurl.h url規格化類，包括host、port、scheme等成員變量)，加載頁面(page()->mainFrame()->load(url) page()函數是全局函數？)。

最終調用QWebFrame::load(Source/WebKit/qt/Api/qwebframe.cpp:885)函數，在該函數中，會構造出ResourceRequest(Source/WebCore/platform/network/qt/ResourceRequest.h繼承ResourceRequestBaseSource/WebCore/platform/network/ResourceRequestBase.cpp)對象，並將這個對象作爲一個參數，調用FrameLoader對象的load函數(Source/WebCore/loader/FrameLoader.cpp:1450)。

FrameLoader類負責將documents加載到Frames。當你點擊一個鏈接的時候，FrameLoader創建一個新的處於”policy”狀態的DocumentLoader對象，等待WebKit客戶端決定是否處理這個加載。通常WebKit客戶端會指示FrameLoader將這個加載視爲一個導航（navigation），而不是阻止加載等。

DocumentLoader類中會維護這個ResourceRequest(FrameLoader.cpp:1460)，policyChecker()
——>checkNavigationPolicy(Source/WebCore/loader/FrameLoader.cpp:1585)

1585         policyChecker()->checkNavigationPolicy(loader->request(), loader, formState,
1586             callContinueLoadAfterNavigationPolicy, this);//回調函數？如下調用

——>m_frame->loader()->client()->dispatchDecidePolicyForNavigationAction(Source/WebCore/loader/PolicyChecker.cpp:87)

 84     m_callback.set(request, formState.get(), function, argument);//callContinueLoadAfterNavigationPolicy

一旦客戶端指示FrameLoader將本次加載視爲一個導航，FrameLoader就推動DocumentLoader進入”provisional”狀態，在該狀態，DocumentLoader會發起一個網絡請求，並等待以確定網絡請求將發起一個下載還是一個新的document。
——>page->d->acceptNavigationRequest（Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1271）
        callPolicyFunction(Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1283)
        回調函數？如上
         //——>(m_frame->loader()->policyChecker()->*function)(action) (245)
——>callback.call(Source/WebCore/loader/PolicyChecker.cpp:160)
——>m_navigationFunction(Source/WebCore/loader/PolicyCallback.cpp:103)
——>loader->continueLoadAfterNavigationPolicy(Source/WebCore/loader/FrameLoader.cpp:2977)

2974 void FrameLoader::callContinueLoadAfterNavigationPolicy(void* argument,
2975     const ResourceRequest& request, PassRefPtr<FormState> formState, bool shouldContinue)
2976 {
2977     FrameLoader* loader = static_cast<FrameLoader*>(argument);
2978     loader->continueLoadAfterNavigationPolicy(request, formState, shouldContinue);
2979 }

——>continueLoadAfterWillSubmitForm(Source/WebCore/loader/FrameLoader.cpp:3105)
——>m_provisionalDocumentLoader->startLoadingMainResource(Source/WebCore/loader/FrameLoader.cpp:2572)

接下去，DocumentLoader會創建一個MainResourceLoader對象，這個對象主要用來通過ResourceHandle接口同平臺網絡庫進行交互。將MainResourceLoader和DocumentLoader分開來主要有兩個目的：（1）MainResourceLoader讓DocumentLoader從處理ResourceHandle回調的細節中抽身出來（2）降低MainResourceLoader的生命週期和DocumentLoader的生命週期（同Document綁定）的耦合度。

——>m_mainResourceLoader->load(Source/WebCore/loader/DocumentLoader.cpp:798)
——>loadNow(Source/WebCore/loader/MainResourceLoader.cpp:612)
——>ResourceHandle::create(Source/WebCore/loader/MainResourceLoader.cpp:585)
——>newHandle->start(Source/WebCore/platform/network/ResourceHandle.cpp:71)
——>new QNetworkReplyHandler(Source/WebCore/platform/network/qt/ResourceHandleQt.cpp:100)
       ——>r.toNetworkRequest(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:399) 設置http頭
——>m_queue.push 提交事件？ (Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:401)
——>flush();(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:164)         
——>(m_replyHandler->*(m_enqueuedCalls.takeFirst()))();（Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:195）
——>QNetworkReplyHandler::start()(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:659) 
        建立連接(ESTABLISHED)、發送請求 665： QNetworkReply* reply = sendNetworkRequest(d->m_context->networkAccessManager(), d->m_firstRequest); 
         ——>601 WebCore::QNetworkReplyHandler::sendNetworkRequest 
               ——>626 manager->get(m_request)
      665     QNetworkReply* reply = sendNetworkRequest(d->m_context->networkAccessManager(), d->m_firstRequest);
      669     m_replyWrapper = new QNetworkReplyWrapper(&m_queue, reply, m_resourceHandle->shouldContentSniff() && d->m_context-
    >mimeSniffingEnabled(), this);
               ——>208 QNetworkReplyWrapper::QNetworkReplyWrapper(QNetworkReplyHandlerCallQueue* queue, QNetworkReply* reply, bool
    sniffMIMETypes, QObject* parent)
                  209     : QObject(parent)
                  210     , m_reply(reply)
                  211     , m_queue(queue)
                  212     , m_responseContainsData(false)
                  213     , m_sniffMIMETypes(sniffMIMETypes)
                  214 {
                   215     Q_ASSERT(m_reply);
                  216 
                  217     // setFinished() must be the first that we connect, so isFinished() is updated when running other slots.
                   //QT通過此種方式異步回調??(yes, 信號、槽機制，http://www.ibm.com/developerworks/cn/linux/guitoolkit/qt/signal-slot/ )
                  218     connect(m_reply, SIGNAL(finished()), this, SLOT(setFinished()));
                  219     connect(m_reply, SIGNAL(finished()), this, SLOT(receiveMetaData()));
                  220     connect(m_reply, SIGNAL(readyRead()), this, SLOT(receiveMetaData()));
                  221 }

一旦加載系統接收到足夠的信息可以確定資源確實代表了document，FrameLoader就將DocumentLoader推向”committed”狀態，在該狀態中，frame將顯示document。

下載完了之後
——>QtMIMETypeSniffer::qt_metacall()(WebKitBuild/Debug/WebCore/moc_QtMIMETypeSniffer.cpp:77) 
——>trySniffing()(Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:59) 
      ——>m_sniffer.sniff(data.constData(), data.size())(Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:51)

 50     QByteArray data = m_reply->peek(m_sniffer.dataSize());
 51     const char* sniffedMimeType = m_sniffer.sniff(data.constData(), data.size());

       data.constData()保存着網頁內容，涉及的變量包括m_reply、m_sniffer

      ——>emit finished (Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:65)    
      ——>QMetaObject::activate(WebKitBuild/Debug/WebCore/moc_QtMIMETypeSniffer.cpp:88)
      ……
      WebCore::QNetworkReplyWrapper::qt_metacall (WebKitBuild/Debug/WebCore/moc_QNetworkReplyHandler.cpp)

77     if (_c == QMetaObject::InvokeMetaMethod) {
 78         switch (_id) {
 79         case 0: receiveMetaData(); break;
 80         case 1: didReceiveFinished(); break;
 81         case 2: didReceiveReadyRead(); break;
 82         case 3: receiveSniffedMIMEType(); break;
 83         case 4: setFinished(); break;
 84         default: ;
 85         }
 86         _id -= 5;
 87     }

      ——>receiveSniffedMIMEType()(WebKitBuild/Debug/WebCore/moc_QNetworkReplyHandler.cpp:82)
      ——>emitMetaDataChanged()(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:305)
         ——>QueueLocker lock(m_queue)(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp)
         ——>~QueueLocker() { m_queue->unlock(); } (203)
         ——>flush();(178)
         ——>(m_replyHandler->*(m_enqueuedCalls.takeFirst()))(); （195）
         
         ——>1、QNetworkReplyHandler::forwardData (572)
         ——>client->didReceiveData(m_resourceHandle, data.constData(), data.length(), -1); (586)
      ——>ResourceLoader::didReceiveData(ResourceHandle*, const char* data, int length, int encodedDataLength) (Source/WebCore/loader/ResourceLoader.cpp:427)
               data指向保存頁面內容
      ——>MainResourceLoader::didReceiveData(Source/WebCore/loader/MainResourceLoader.cpp:431)
      ——>ResourceLoader::didReceiveData (Source/WebCore/loader/ResourceLoader.cpp:267)

279     addData(data, length, allAtOnce);
280     // FIXME: If we get a resource with more than 2B bytes, this code won't do the right thing.
281     // However, with today's computers and networking speeds, this won't happen in practice.
282     // Could be an issue with a giant local file.
283     if (m_sendResourceLoadCallbacks && m_frame)
284         frameLoader()->notifier()->didReceiveData(this, data, length, static_cast<int>(encodedDataLength));

            保存頁面到cache 函數： addData()
      ——>ResourceLoadNotifier::didReceiveData(Source/WebCore/loader/ResourceLoadNotifier.cpp:77)
         ——>ResourceLoadNotifier::dispatchDidReceiveContentLength (133)
      ——>InspectorInstrumentation::didReceiveContentLength（Source/WebCore/inspector/InspectorInstrumentation.h：713）
      ——>InspectorInstrumentation::didReceiveContentLengthImpl（Source/WebCore/inspector/InspectorInstrumentation.cpp：487）
 
html解析     
      ——>2、QNetworkReplyHandler::finish(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:437)
      ——>ResourceLoader::didFinishLoading (Source/WebCore/loader/ResourceLoader.cpp:434)
      ——>MainResourceLoader::didFinishLoading(Source/WebCore/loader/MainResourceLoader.cpp:466)
      ——>FrameLoader::finishedLoading (Source/WebCore/loader/FrameLoader.cpp：2287)
      ——>DocumentLoader::finishedLoading (Source/WebCore/loader/DocumentLoader.cpp:282)
         ——>FrameLoader::finishedLoadingDocument(DocumentLoader* loader) (Source/WebCore/loader/FrameLoader.cpp:2333)
            ——>FrameLoaderClientQt::finishedLoading(DocumentLoader* loader)(Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:626)
         ——>DocumentWriter::end() (Source/WebCore/loader/DocumentWriter.cpp:211)

211 void DocumentWriter::end()
212 {
213     m_frame->loader()->didEndDocument();
214     endIfNotLoadingMainResource();
215 }

            213 ——>Document::finishParsing() (Source/WebCore/dom/Document.cpp:2246)
            214： DocumentWriter::endIfNotLoadingMainResource() （Source/WebCore/loader/DocumentWriter.cpp  228）

228     addData(0, 0, true);
229     m_frame->document()->finishParsing();

               ——>DocumentWriter::addData() (208)               
                  ——>DecodedDataDocumentParser::appendBytes(DocumentWriter* writer , const char* data, int length, bool shouldFlush)（Source/WebCore/dom/DecodedDataDocumentParser.cpp：40）
                  ——> HTMLDocumentParser::append(const SegmentedString& source) (Source/WebCore/html/parser/HTMLDocumentParser.cpp:367)
                  ——> HTMLDocumentParser::pumpTokenizerIfPossible(SynchronousMode mode) (175)
                  ——> HTMLDocumentParser::pumpTokenizer(SynchronousMode mode) (261)
                  解析、執行script
                     ——> HTMLDocumentParser::canTakeNextToken(SynchronousMode mode, PumpSession& session) (223)
                     ——> HTMLDocumentParser::runScriptsForPausedTreeBuilder() (205)
                     ——> HTMLScriptRunner::execute(PassRefPtr<Element> scriptElement, const TextPosition1& scriptStartPosition) Source/WebCore/html/parser/HTMLScriptRunner.cpp:167)
                     ——> WebCore::HTMLScriptRunner::runScript(this=0x81e2a58, script=0x832c040, scriptStartPosition=...) (296)
                     ——> WebCore::ScriptElement::prepareScript (this=0x832c084, scriptStartPosition=...,     supportLegacyTypes=WebCore::ScriptElement::DisallowLegacyTypeInTypeAttribute)(Source/WebCore/dom/ScriptElement.cpp:240)
                     ——> WebCore::ScriptElement::executeScript (this=0x832c084, sourceCode=...)(283)
                     ——> WebCore::ScriptController::evaluate (this=0x828d1a4, sourceCode=...)(Source/WebCore/bindings/js/ScriptController.cpp:166)
                     ——> WebCore::ScriptController::evaluateInWorld (143)
                     ——> WebCore::JSMainThreadExecState::evaluate(Source/WebCore/bindings/js/JSMainThreadExecState.h:54)
                     ——> JSC::evaluate(exec=0xae3f499c, scopeChain=0xae3ee5c8, source=..., thisValue=...) (Source/JavaScriptCore/runtime/Completion.cpp:64)
                     ——> JSC::Interpreter::execute(Source/JavaScriptCore/interpreter/Interpreter.cpp:767)
                     ——> JSC::JITCode::execute (Source/JavaScriptCore/jit/JITCode.h:77)
                     ——> ?? ()
                     ——>WebCore::jsHTMLDocumentPrototypeFunctionWrite(WebCore/generated/JSHTMLDocument.cpp:445)
                     ——> WebCore::JSHTMLDocument::write(Source/WebCore/bindings/js/JSHTMLDocumentCustom.cpp:161)
                     ——> WebCore::documentWrite (156)
                     ——> WebCore::Document::write (Source/WebCore/dom/Document.cpp:2227)
                           ——> WebCore::HTMLDocumentParser::insert(Source/WebCore/html/parser/HTMLDocumentParser.cpp:324)
                              回到了html的解析
                           ——> WebCore::HTMLDocumentParser::pumpTokenizerIfPossible (175)
                           ——> WebCore::HTMLDocumentParser::pumpTokenizer  (299)
                                    查看是否有script，1、如果有，轉到“ 解析、執行script”；2、如果沒有轉到下面“”
                  完成解析html
                  InspectorInstrumentation::didWriteHTML(cookie, m_tokenizer->lineNumber());
                  ——> InspectorInstrumentation::didWriteHTML (Source/WebCore/inspector/InspectorInstrumentation.h:803)
                  ——> 
            ——> Document::finishParsing() (Source/WebCore/dom/Document.cpp:2259)
                  ——>HTMLDocumentParser::finish() (Source/WebCore/html/parser/HTMLDocumentParser.cpp:427)
                  ——>HTMLDocumentParser::attemptToEnd() (399)
                  ——> 
                  
 生成dom樹     
      


附件(js)下載、解析



      


二、下載
三、加載

參考文檔
1.官方文檔：http://www.webkit.org/blog/1188/how-webkit-loads-a-web-page/
2.dlmu2001的譯文：http://blog.csdn.net/dlmu2001/article/details/5941432
3.dlmu200：WebCore中的http請求信息維護 http://blog.csdn.net/dlmu2001/article/details/59361221
4.其他技術性文章：Introduction to WebKit Objective-C Programming Guide http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/DisplayWebContent/DisplayWebContent.html
5.其他技術性文章：Introduction to WebKit DOM Programming Topicshttp://developer.apple.com/library/mac/#documentation/AppleApplications/Conceptual/SafariJSProgTopics/WebKitJavaScript.html
6. http://www.webkit.org/coding/technical-articles.html

相關技巧
1.cscope查找類的定義：cs find e class.*QString[^;]*($|{)