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Diffstat (limited to 'dom/worklet/WorkletThread.cpp')
| -rw-r--r-- | dom/worklet/WorkletThread.cpp | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/dom/worklet/WorkletThread.cpp b/dom/worklet/WorkletThread.cpp new file mode 100644 index 0000000000..c5ad7070b0 --- /dev/null +++ b/dom/worklet/WorkletThread.cpp @@ -0,0 +1,474 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "WorkletThread.h" +#include "prthread.h" +#include "nsContentUtils.h" +#include "nsCycleCollector.h" +#include "nsJSEnvironment.h" +#include "nsJSPrincipals.h" +#include "mozilla/dom/AtomList.h" +#include "mozilla/dom/WorkletGlobalScope.h" +#include "mozilla/ipc/BackgroundChild.h" +#include "mozilla/Attributes.h" +#include "mozilla/CycleCollectedJSRuntime.h" +#include "mozilla/EventQueue.h" +#include "mozilla/ThreadEventQueue.h" +#include "js/ContextOptions.h" +#include "js/Exception.h" +#include "js/Initialization.h" +#include "XPCSelfHostedShmem.h" + +namespace mozilla::dom { + +namespace { + +// The size of the worklet runtime heaps in bytes. +#define WORKLET_DEFAULT_RUNTIME_HEAPSIZE 32 * 1024 * 1024 + +// The C stack size. We use the same stack size on all platforms for +// consistency. +const uint32_t kWorkletStackSize = 256 * sizeof(size_t) * 1024; + +// Half the size of the actual C stack, to be safe. +#define WORKLET_CONTEXT_NATIVE_STACK_LIMIT 128 * sizeof(size_t) * 1024 + +// Helper functions + +bool PreserveWrapper(JSContext* aCx, JS::Handle<JSObject*> aObj) { + MOZ_ASSERT(aCx); + MOZ_ASSERT(aObj); + MOZ_ASSERT(mozilla::dom::IsDOMObject(aObj)); + return mozilla::dom::TryPreserveWrapper(aObj); +} + +JSObject* Wrap(JSContext* aCx, JS::Handle<JSObject*> aExisting, + JS::Handle<JSObject*> aObj) { + if (aExisting) { + js::Wrapper::Renew(aExisting, aObj, + &js::OpaqueCrossCompartmentWrapper::singleton); + } + + return js::Wrapper::New(aCx, aObj, + &js::OpaqueCrossCompartmentWrapper::singleton); +} + +const JSWrapObjectCallbacks WrapObjectCallbacks = { + Wrap, + nullptr, +}; + +} // namespace + +// This classes control CC in the worklet thread. + +class WorkletJSRuntime final : public mozilla::CycleCollectedJSRuntime { + public: + explicit WorkletJSRuntime(JSContext* aCx) : CycleCollectedJSRuntime(aCx) {} + + ~WorkletJSRuntime() override = default; + + virtual void PrepareForForgetSkippable() override {} + + virtual void BeginCycleCollectionCallback( + mozilla::CCReason aReason) override {} + + virtual void EndCycleCollectionCallback( + CycleCollectorResults& aResults) override {} + + virtual void DispatchDeferredDeletion(bool aContinuation, + bool aPurge) override { + MOZ_ASSERT(!aContinuation); + nsCycleCollector_doDeferredDeletion(); + } + + virtual void CustomGCCallback(JSGCStatus aStatus) override { + // nsCycleCollector_collect() requires a cycle collector but + // ~WorkletJSContext calls nsCycleCollector_shutdown() and the base class + // destructor will trigger a final GC. The nsCycleCollector_collect() + // call can be skipped in this GC as ~CycleCollectedJSContext removes the + // context from |this|. + if (aStatus == JSGC_END && GetContext()) { + nsCycleCollector_collect(CCReason::GC_FINISHED, nullptr); + } + } +}; + +class WorkletJSContext final : public CycleCollectedJSContext { + public: + WorkletJSContext() { + MOZ_ASSERT(!NS_IsMainThread()); + + nsCycleCollector_startup(); + } + + // MOZ_CAN_RUN_SCRIPT_BOUNDARY because otherwise we have to annotate the + // SpiderMonkey JS::JobQueue's destructor as MOZ_CAN_RUN_SCRIPT, which is a + // bit of a pain. + MOZ_CAN_RUN_SCRIPT_BOUNDARY ~WorkletJSContext() override { + MOZ_ASSERT(!NS_IsMainThread()); + + JSContext* cx = MaybeContext(); + if (!cx) { + return; // Initialize() must have failed + } + + nsCycleCollector_shutdown(); + } + + WorkletJSContext* GetAsWorkletJSContext() override { return this; } + + CycleCollectedJSRuntime* CreateRuntime(JSContext* aCx) override { + return new WorkletJSRuntime(aCx); + } + + nsresult Initialize(JSRuntime* aParentRuntime) { + MOZ_ASSERT(!NS_IsMainThread()); + + nsresult rv = CycleCollectedJSContext::Initialize( + aParentRuntime, WORKLET_DEFAULT_RUNTIME_HEAPSIZE); + if (NS_WARN_IF(NS_FAILED(rv))) { + return rv; + } + + JSContext* cx = Context(); + + js::SetPreserveWrapperCallbacks(cx, PreserveWrapper, HasReleasedWrapper); + JS_InitDestroyPrincipalsCallback(cx, nsJSPrincipals::Destroy); + JS_InitReadPrincipalsCallback(cx, nsJSPrincipals::ReadPrincipals); + JS_SetWrapObjectCallbacks(cx, &WrapObjectCallbacks); + JS_SetFutexCanWait(cx); + + return NS_OK; + } + + void DispatchToMicroTask( + already_AddRefed<MicroTaskRunnable> aRunnable) override { + RefPtr<MicroTaskRunnable> runnable(aRunnable); + + MOZ_ASSERT(!NS_IsMainThread()); + MOZ_ASSERT(runnable); + + JSContext* cx = Context(); + MOZ_ASSERT(cx); + +#ifdef DEBUG + JS::Rooted<JSObject*> global(cx, JS::CurrentGlobalOrNull(cx)); + MOZ_ASSERT(global); +#endif + + JS::JobQueueMayNotBeEmpty(cx); + GetMicroTaskQueue().push_back(std::move(runnable)); + } + + bool IsSystemCaller() const override { + // Currently no support for special system worklet privileges. + return false; + } + + void ReportError(JSErrorReport* aReport, + JS::ConstUTF8CharsZ aToStringResult) override; + + uint64_t GetCurrentWorkletWindowID() { + JSObject* global = JS::CurrentGlobalOrNull(Context()); + if (NS_WARN_IF(!global)) { + return 0; + } + nsIGlobalObject* nativeGlobal = xpc::NativeGlobal(global); + nsCOMPtr<WorkletGlobalScope> workletGlobal = + do_QueryInterface(nativeGlobal); + if (NS_WARN_IF(!workletGlobal)) { + return 0; + } + return workletGlobal->Impl()->LoadInfo().InnerWindowID(); + } +}; + +void WorkletJSContext::ReportError(JSErrorReport* aReport, + JS::ConstUTF8CharsZ aToStringResult) { + RefPtr<xpc::ErrorReport> xpcReport = new xpc::ErrorReport(); + xpcReport->Init(aReport, aToStringResult.c_str(), IsSystemCaller(), + GetCurrentWorkletWindowID()); + RefPtr<AsyncErrorReporter> reporter = new AsyncErrorReporter(xpcReport); + + JSContext* cx = Context(); + if (JS_IsExceptionPending(cx)) { + JS::ExceptionStack exnStack(cx); + if (JS::StealPendingExceptionStack(cx, &exnStack)) { + JS::Rooted<JSObject*> stack(cx); + JS::Rooted<JSObject*> stackGlobal(cx); + xpc::FindExceptionStackForConsoleReport(nullptr, exnStack.exception(), + exnStack.stack(), &stack, + &stackGlobal); + if (stack) { + reporter->SerializeStack(cx, stack); + } + } + } + + NS_DispatchToMainThread(reporter); +} + +// This is the first runnable to be dispatched. It calls the RunEventLoop() so +// basically everything happens into this runnable. The reason behind this +// approach is that, when the Worklet is terminated, it must not have any JS in +// stack, but, because we have CC, nsIThread creates an AutoNoJSAPI object by +// default. Using this runnable, CC exists only into it. +class WorkletThread::PrimaryRunnable final : public Runnable { + public: + explicit PrimaryRunnable(WorkletThread* aWorkletThread) + : Runnable("WorkletThread::PrimaryRunnable"), + mWorkletThread(aWorkletThread) { + MOZ_ASSERT(aWorkletThread); + MOZ_ASSERT(NS_IsMainThread()); + } + + NS_IMETHOD + Run() override { + mWorkletThread->RunEventLoop(); + return NS_OK; + } + + private: + RefPtr<WorkletThread> mWorkletThread; +}; + +// This is the last runnable to be dispatched. It calls the TerminateInternal() +class WorkletThread::TerminateRunnable final : public Runnable { + public: + explicit TerminateRunnable(WorkletThread* aWorkletThread) + : Runnable("WorkletThread::TerminateRunnable"), + mWorkletThread(aWorkletThread) { + MOZ_ASSERT(aWorkletThread); + MOZ_ASSERT(NS_IsMainThread()); + } + + NS_IMETHOD + Run() override { + mWorkletThread->TerminateInternal(); + return NS_OK; + } + + private: + RefPtr<WorkletThread> mWorkletThread; +}; + +WorkletThread::WorkletThread(WorkletImpl* aWorkletImpl) + : nsThread( + MakeNotNull<ThreadEventQueue*>(MakeUnique<mozilla::EventQueue>()), + nsThread::NOT_MAIN_THREAD, {.stackSize = kWorkletStackSize}), + mWorkletImpl(aWorkletImpl), + mExitLoop(false), + mIsTerminating(false) { + MOZ_ASSERT(NS_IsMainThread()); + nsContentUtils::RegisterShutdownObserver(this); +} + +WorkletThread::~WorkletThread() = default; + +// static +already_AddRefed<WorkletThread> WorkletThread::Create( + WorkletImpl* aWorkletImpl) { + RefPtr<WorkletThread> thread = new WorkletThread(aWorkletImpl); + if (NS_WARN_IF(NS_FAILED(thread->Init("DOM Worklet"_ns)))) { + return nullptr; + } + + RefPtr<PrimaryRunnable> runnable = new PrimaryRunnable(thread); + if (NS_WARN_IF(NS_FAILED(thread->DispatchRunnable(runnable.forget())))) { + return nullptr; + } + + return thread.forget(); +} + +nsresult WorkletThread::DispatchRunnable( + already_AddRefed<nsIRunnable> aRunnable) { + nsCOMPtr<nsIRunnable> runnable(aRunnable); + return nsThread::Dispatch(runnable.forget(), NS_DISPATCH_NORMAL); +} + +NS_IMETHODIMP +WorkletThread::DispatchFromScript(nsIRunnable* aRunnable, uint32_t aFlags) { + nsCOMPtr<nsIRunnable> runnable(aRunnable); + return Dispatch(runnable.forget(), aFlags); +} + +NS_IMETHODIMP +WorkletThread::Dispatch(already_AddRefed<nsIRunnable> aRunnable, + uint32_t aFlags) { + nsCOMPtr<nsIRunnable> runnable(aRunnable); + + // Worklet only supports asynchronous dispatch. + if (NS_WARN_IF(aFlags != NS_DISPATCH_NORMAL)) { + return NS_ERROR_UNEXPECTED; + } + + return nsThread::Dispatch(runnable.forget(), NS_DISPATCH_NORMAL); +} + +NS_IMETHODIMP +WorkletThread::DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t aFlags) { + return NS_ERROR_NOT_IMPLEMENTED; +} + +static bool DispatchToEventLoop(void* aClosure, + JS::Dispatchable* aDispatchable) { + // This callback may execute either on the worklet thread or a random + // JS-internal helper thread. + + // See comment at JS::InitDispatchToEventLoop() below for how we know the + // thread is alive. + nsIThread* thread = static_cast<nsIThread*>(aClosure); + + nsresult rv = thread->Dispatch( + NS_NewRunnableFunction( + "WorkletThread::DispatchToEventLoop", + [aDispatchable]() { + CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get(); + if (!ccjscx) { + return; + } + + WorkletJSContext* wjc = ccjscx->GetAsWorkletJSContext(); + if (!wjc) { + return; + } + + aDispatchable->run(wjc->Context(), + JS::Dispatchable::NotShuttingDown); + }), + NS_DISPATCH_NORMAL); + + return NS_SUCCEEDED(rv); +} + +// static +void WorkletThread::EnsureCycleCollectedJSContext( + JSRuntime* aParentRuntime, const JS::ContextOptions& aOptions) { + CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get(); + if (ccjscx) { + MOZ_ASSERT(ccjscx->GetAsWorkletJSContext()); + return; + } + + WorkletJSContext* context = new WorkletJSContext(); + nsresult rv = context->Initialize(aParentRuntime); + if (NS_WARN_IF(NS_FAILED(rv))) { + // TODO: error propagation + return; + } + + JS::ContextOptionsRef(context->Context()) = aOptions; + + JS_SetGCParameter(context->Context(), JSGC_MAX_BYTES, uint32_t(-1)); + + // FIXME: JS_SetDefaultLocale + // FIXME: JSSettings + // FIXME: JS_SetSecurityCallbacks + // FIXME: JS::SetAsyncTaskCallbacks + // FIXME: JS::SetCTypesActivityCallback + // FIXME: JS_SetGCZeal + + // A thread lives strictly longer than its JSRuntime so we can safely + // store a raw pointer as the callback's closure argument on the JSRuntime. + JS::InitDispatchToEventLoop(context->Context(), DispatchToEventLoop, + NS_GetCurrentThread()); + + JS_SetNativeStackQuota(context->Context(), + WORKLET_CONTEXT_NATIVE_STACK_LIMIT); + + // When available, set the self-hosted shared memory to be read, so that we + // can decode the self-hosted content instead of parsing it. + auto& shm = xpc::SelfHostedShmem::GetSingleton(); + JS::SelfHostedCache selfHostedContent = shm.Content(); + + if (!JS::InitSelfHostedCode(context->Context(), selfHostedContent)) { + // TODO: error propagation + return; + } +} + +void WorkletThread::RunEventLoop() { + MOZ_ASSERT(!NS_IsMainThread()); + + PR_SetCurrentThreadName("worklet"); + + while (!mExitLoop) { + MOZ_ALWAYS_TRUE(NS_ProcessNextEvent(this, /* wait: */ true)); + } + + DeleteCycleCollectedJSContext(); +} + +void WorkletThread::Terminate() { + MOZ_ASSERT(NS_IsMainThread()); + + if (mIsTerminating) { + // nsThread::Dispatch() would leak the runnable if the event queue is no + // longer accepting runnables. + return; + } + + mIsTerminating = true; + + nsContentUtils::UnregisterShutdownObserver(this); + + RefPtr<TerminateRunnable> runnable = new TerminateRunnable(this); + DispatchRunnable(runnable.forget()); +} + +void WorkletThread::TerminateInternal() { + MOZ_ASSERT(!CycleCollectedJSContext::Get() || IsOnWorkletThread()); + + mExitLoop = true; + + nsCOMPtr<nsIRunnable> runnable = NewRunnableMethod( + "WorkletThread::Shutdown", this, &WorkletThread::Shutdown); + NS_DispatchToMainThread(runnable); +} + +/* static */ +void WorkletThread::DeleteCycleCollectedJSContext() { + CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get(); + if (!ccjscx) { + return; + } + + // Release any MessagePort kept alive by its ipc actor. + mozilla::ipc::BackgroundChild::CloseForCurrentThread(); + + WorkletJSContext* workletjscx = ccjscx->GetAsWorkletJSContext(); + MOZ_ASSERT(workletjscx); + delete workletjscx; +} + +/* static */ +bool WorkletThread::IsOnWorkletThread() { + CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get(); + return ccjscx && ccjscx->GetAsWorkletJSContext(); +} + +/* static */ +void WorkletThread::AssertIsOnWorkletThread() { + MOZ_ASSERT(IsOnWorkletThread()); +} + +// nsIObserver +NS_IMETHODIMP +WorkletThread::Observe(nsISupports* aSubject, const char* aTopic, + const char16_t*) { + MOZ_ASSERT(strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0); + + // The WorkletImpl will terminate the worklet thread after sending a message + // to release worklet thread objects. + mWorkletImpl->NotifyWorkletFinished(); + return NS_OK; +} + +NS_IMPL_ISUPPORTS_INHERITED(WorkletThread, nsThread, nsIObserver) + +} // namespace mozilla::dom |