[proof-of-concept] SW thread independent of the main thread

third_party/WebKit/Source/core/workers/WorkerThread.cpp

Index: third_party/WebKit/Source/core/workers/WorkerThread.cpp
diff --git a/third_party/WebKit/Source/core/workers/WorkerThread.cpp b/third_party/WebKit/Source/core/workers/WorkerThread.cpp
index 55ad091a54ccf1baa29fcba78dbd20b35ff2b287..ad825e712448374d94451b2be05f6459888893bf 100644
--- a/third_party/WebKit/Source/core/workers/WorkerThread.cpp
+++ b/third_party/WebKit/Source/core/workers/WorkerThread.cpp
@@ -47,6 +47,7 @@
 #include "platform/heap/SafePoint.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/scheduler/CancellableTaskFactory.h"
+#include "platform/TraceEvent.h"
 #include "platform/weborigin/KURL.h"
 #include "public/platform/WebThread.h"
 #include "wtf/Functional.h"
@@ -190,7 +191,9 @@ WorkerThread::~WorkerThread()
 
 void WorkerThread::start(std::unique_ptr<WorkerThreadStartupData> startupData)
 {
-    DCHECK(isMainThread());
+
+    if (m_launchedFromMainThread)
+        DCHECK(isMainThread());
 
     if (m_requestedToStart)
         return;
@@ -349,16 +352,19 @@ bool WorkerThread::isForciblyTerminated()
     return false;
 }
 
-WorkerThread::WorkerThread(PassRefPtr<WorkerLoaderProxy> workerLoaderProxy, WorkerReportingProxy& workerReportingProxy)
+WorkerThread::WorkerThread(PassRefPtr<WorkerLoaderProxy> workerLoaderProxy, WorkerReportingProxy& workerReportingProxy, bool launchedFromMainThread)
     : m_forceTerminationDelayInMs(kForceTerminationDelayInMs)
     , m_inspectorTaskRunner(wrapUnique(new InspectorTaskRunner()))
     , m_workerLoaderProxy(workerLoaderProxy)
     , m_workerReportingProxy(workerReportingProxy)
     , m_shutdownEvent(wrapUnique(new WaitableEvent(
-        WaitableEvent::ResetPolicy::Manual,
-        WaitableEvent::InitialState::NonSignaled)))
-    , m_workerThreadLifecycleContext(new WorkerThreadLifecycleContext)
+          WaitableEvent::ResetPolicy::Manual,
+          WaitableEvent::InitialState::NonSignaled)))
+    , m_workerThreadLifecycleContext(launchedFromMainThread ? new WorkerThreadLifecycleContext : nullptr)
+    , m_launchedFromMainThread(launchedFromMainThread)
 {
+    if (!m_launchedFromMainThread)
+        return;
     DCHECK(isMainThread());
     MutexLocker lock(threadSetMutex());
     workerThreads().add(this);
@@ -476,6 +482,10 @@ bool WorkerThread::isInShutdown()
 void WorkerThread::initializeOnWorkerThread(std::unique_ptr<WorkerThreadStartupData> startupData)
 {
     DCHECK(isCurrentThread());
+
+    TRACE_EVENT0("ServiceWorker", "WorkerThread::initializeOnWorkerThread");
+    m_workerReportingProxy.initializeOnWorkerThread();
+
     KURL scriptURL = startupData->m_scriptURL;
     String sourceCode = startupData->m_sourceCode;
     WorkerThreadStartMode startMode = startupData->m_startMode;
@@ -500,11 +510,13 @@ void WorkerThread::initializeOnWorkerThread(std::unique_ptr<WorkerThreadStartupD
             return;
         }
 
-        if (isOwningBackingThread())
+        if (isOwningBackingThread()) {
             workerBackingThread().initialize();
+        }
 
-        if (shouldAttachThreadDebugger())
+        if (shouldAttachThreadDebugger()) {
             V8PerIsolateData::from(isolate())->setThreadDebugger(wrapUnique(new WorkerThreadDebugger(this, isolate())));
+        }
         m_microtaskRunner = wrapUnique(new WorkerMicrotaskRunner(this));
         workerBackingThread().backingThread().addTaskObserver(m_microtaskRunner.get());
 
@@ -552,8 +564,22 @@ void WorkerThread::initializeOnWorkerThread(std::unique_ptr<WorkerThreadStartupD
 
     if (globalScope()->isWorkerGlobalScope()) {
         WorkerGlobalScope* workerGlobalScope = toWorkerGlobalScope(globalScope());
-        CachedMetadataHandler* handler = workerGlobalScope->createWorkerScriptCachedMetadataHandler(scriptURL, cachedMetaData.get());
-        bool success = workerGlobalScope->scriptController()->evaluate(ScriptSourceCode(sourceCode, scriptURL), nullptr, handler, v8CacheOptions);
+        std::unique_ptr<String> alternativeCode(m_workerReportingProxy.takeAlternativeCode(scriptURL));
+        bool success = false;
+
+        if (alternativeCode) {
+            CachedMetadataHandler* handler = workerGlobalScope->createWorkerScriptCachedMetadataHandler(scriptURL, cachedMetaData.get());
+            {
+                TRACE_EVENT0("ServiceWorker", "WorkerThread::initializeOnWorkerThread::evaluate");
+                success = workerGlobalScope->scriptController()->evaluate(ScriptSourceCode(*alternativeCode, scriptURL), nullptr, handler, v8CacheOptions);
+            }
+        } else {
+            CachedMetadataHandler* handler = workerGlobalScope->createWorkerScriptCachedMetadataHandler(scriptURL, cachedMetaData.get());
+            {
+                TRACE_EVENT0("ServiceWorker", "WorkerThread::initializeOnWorkerThread::evaluate");
+                success = workerGlobalScope->scriptController()->evaluate(ScriptSourceCode(sourceCode, scriptURL), nullptr, handler, v8CacheOptions);
+            }
+        }
         workerGlobalScope->didEvaluateWorkerScript();
         m_workerReportingProxy.didEvaluateWorkerScript(success);
     }