michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=8 sts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsCxPusher.h"
michael@0: 
michael@0: #include "nsIScriptContext.h"
michael@0: #include "mozilla/dom/EventTarget.h"
michael@0: #include "nsDOMJSUtils.h"
michael@0: #include "xpcprivate.h"
michael@0: #include "WorkerPrivate.h"
michael@0: 
michael@0: using mozilla::dom::EventTarget;
michael@0: using mozilla::DebugOnly;
michael@0: 
michael@0: bool
michael@0: nsCxPusher::Push(EventTarget *aCurrentTarget)
michael@0: {
michael@0:   MOZ_ASSERT(mPusher.empty());
michael@0:   NS_ENSURE_TRUE(aCurrentTarget, false);
michael@0:   nsresult rv;
michael@0:   nsIScriptContext* scx =
michael@0:     aCurrentTarget->GetContextForEventHandlers(&rv);
michael@0: #ifdef DEBUG_smaug
michael@0:   NS_ENSURE_SUCCESS(rv, false);
michael@0: #else
michael@0:   if(NS_FAILED(rv)) {
michael@0:     return false;
michael@0:   }
michael@0: #endif
michael@0: 
michael@0:   if (!scx) {
michael@0:     // The target may have a special JS context for event handlers.
michael@0:     JSContext* cx = aCurrentTarget->GetJSContextForEventHandlers();
michael@0:     if (cx) {
michael@0:       mPusher.construct(cx);
michael@0:     }
michael@0: 
michael@0:     // Nothing to do here, I guess.  Have to return true so that event firing
michael@0:     // will still work correctly even if there is no associated JSContext
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   mPusher.construct(scx->GetNativeContext());
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool
michael@0: nsCxPusher::RePush(EventTarget *aCurrentTarget)
michael@0: {
michael@0:   if (mPusher.empty()) {
michael@0:     return Push(aCurrentTarget);
michael@0:   }
michael@0: 
michael@0:   if (aCurrentTarget) {
michael@0:     nsresult rv;
michael@0:     nsIScriptContext* scx =
michael@0:       aCurrentTarget->GetContextForEventHandlers(&rv);
michael@0:     if (NS_FAILED(rv)) {
michael@0:       mPusher.destroy();
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     // If we have the same script context and native context is still
michael@0:     // alive, no need to Pop/Push.
michael@0:     if (scx && scx == mPusher.ref().GetScriptContext() &&
michael@0:         scx->GetNativeContext()) {
michael@0:       return true;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   mPusher.destroy();
michael@0:   return Push(aCurrentTarget);
michael@0: }
michael@0: 
michael@0: void
michael@0: nsCxPusher::Push(JSContext *cx)
michael@0: {
michael@0:   mPusher.construct(cx);
michael@0: }
michael@0: 
michael@0: void
michael@0: nsCxPusher::PushNull()
michael@0: {
michael@0:   // Note: The Maybe<> template magic seems to need the static_cast below to
michael@0:   // work right on some older compilers.
michael@0:   mPusher.construct(static_cast<JSContext*>(nullptr), /* aAllowNull = */ true);
michael@0: }
michael@0: 
michael@0: void
michael@0: nsCxPusher::Pop()
michael@0: {
michael@0:   if (!mPusher.empty())
michael@0:     mPusher.destroy();
michael@0: }
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: AutoCxPusher::AutoCxPusher(JSContext* cx, bool allowNull)
michael@0: {
michael@0:   MOZ_ASSERT_IF(!allowNull, cx);
michael@0: 
michael@0:   // Hold a strong ref to the nsIScriptContext, if any. This ensures that we
michael@0:   // only destroy the mContext of an nsJSContext when it is not on the cx stack
michael@0:   // (and therefore not in use). See nsJSContext::DestroyJSContext().
michael@0:   if (cx)
michael@0:     mScx = GetScriptContextFromJSContext(cx);
michael@0: 
michael@0:   XPCJSContextStack *stack = XPCJSRuntime::Get()->GetJSContextStack();
michael@0:   if (!stack->Push(cx)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0:   mStackDepthAfterPush = stack->Count();
michael@0: 
michael@0: #ifdef DEBUG
michael@0:   mPushedContext = cx;
michael@0:   mCompartmentDepthOnEntry = cx ? js::GetEnterCompartmentDepth(cx) : 0;
michael@0: #endif
michael@0: 
michael@0:   // Enter a request and a compartment for the duration that the cx is on the
michael@0:   // stack if non-null.
michael@0:   if (cx) {
michael@0:     mAutoRequest.construct(cx);
michael@0: 
michael@0:     // DOM JSContexts don't store their default compartment object on the cx.
michael@0:     JSObject *compartmentObject = mScx ? mScx->GetWindowProxy()
michael@0:                                        : js::DefaultObjectForContextOrNull(cx);
michael@0:     if (compartmentObject)
michael@0:       mAutoCompartment.construct(cx, compartmentObject);
michael@0:   }
michael@0: }
michael@0: 
michael@0: AutoCxPusher::~AutoCxPusher()
michael@0: {
michael@0:   // GC when we pop a script entry point. This is a useful heuristic that helps
michael@0:   // us out on certain (flawed) benchmarks like sunspider, because it lets us
michael@0:   // avoid GCing during the timing loop.
michael@0:   //
michael@0:   // NB: We need to take care to only do this if we're in a compartment,
michael@0:   // otherwise JS_MaybeGC will segfault.
michael@0:   if (mScx && !mAutoCompartment.empty())
michael@0:     JS_MaybeGC(nsXPConnect::XPConnect()->GetCurrentJSContext());
michael@0: 
michael@0:   // Leave the compartment and request before popping.
michael@0:   mAutoCompartment.destroyIfConstructed();
michael@0:   mAutoRequest.destroyIfConstructed();
michael@0: 
michael@0:   // When we push a context, we may save the frame chain and pretend like we
michael@0:   // haven't entered any compartment. This gets restored on Pop(), but we can
michael@0:   // run into trouble if a Push/Pop are interleaved with a
michael@0:   // JSAutoEnterCompartment. Make sure the compartment depth right before we
michael@0:   // pop is the same as it was right after we pushed.
michael@0:   MOZ_ASSERT_IF(mPushedContext, mCompartmentDepthOnEntry ==
michael@0:                                 js::GetEnterCompartmentDepth(mPushedContext));
michael@0:   DebugOnly<JSContext*> stackTop;
michael@0:   MOZ_ASSERT(mPushedContext == nsXPConnect::XPConnect()->GetCurrentJSContext());
michael@0:   XPCJSRuntime::Get()->GetJSContextStack()->Pop();
michael@0:   mScx = nullptr;
michael@0: }
michael@0: 
michael@0: bool
michael@0: AutoCxPusher::IsStackTop()
michael@0: {
michael@0:   uint32_t currentDepth = XPCJSRuntime::Get()->GetJSContextStack()->Count();
michael@0:   MOZ_ASSERT(currentDepth >= mStackDepthAfterPush);
michael@0:   return currentDepth == mStackDepthAfterPush;
michael@0: }
michael@0: 
michael@0: AutoJSContext::AutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
michael@0:   : mCx(nullptr)
michael@0: {
michael@0:   Init(false MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
michael@0: }
michael@0: 
michael@0: AutoJSContext::AutoJSContext(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
michael@0:   : mCx(nullptr)
michael@0: {
michael@0:   Init(aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
michael@0: }
michael@0: 
michael@0: void
michael@0: AutoJSContext::Init(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
michael@0: {
michael@0:   JS::AutoAssertNoGC nogc;
michael@0:   MOZ_ASSERT(!mCx, "mCx should not be initialized!");
michael@0: 
michael@0:   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
michael@0: 
michael@0:   nsXPConnect *xpc = nsXPConnect::XPConnect();
michael@0:   if (!aSafe) {
michael@0:     mCx = xpc->GetCurrentJSContext();
michael@0:   }
michael@0: 
michael@0:   if (!mCx) {
michael@0:     mCx = xpc->GetSafeJSContext();
michael@0:     mPusher.construct(mCx);
michael@0:   }
michael@0: }
michael@0: 
michael@0: AutoJSContext::operator JSContext*() const
michael@0: {
michael@0:   return mCx;
michael@0: }
michael@0: 
michael@0: ThreadsafeAutoJSContext::ThreadsafeAutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
michael@0: {
michael@0:   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
michael@0: 
michael@0:   if (NS_IsMainThread()) {
michael@0:     mCx = nullptr;
michael@0:     mAutoJSContext.construct();
michael@0:   } else {
michael@0:     mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
michael@0:     mRequest.construct(mCx);
michael@0:   }
michael@0: }
michael@0: 
michael@0: ThreadsafeAutoJSContext::operator JSContext*() const
michael@0: {
michael@0:   if (mCx) {
michael@0:     return mCx;
michael@0:   } else {
michael@0:     return mAutoJSContext.ref();
michael@0:   }
michael@0: }
michael@0: 
michael@0: AutoSafeJSContext::AutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
michael@0:   : AutoJSContext(true MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
michael@0:   , mAc(mCx, XPCJSRuntime::Get()->GetJSContextStack()->GetSafeJSContextGlobal())
michael@0: {
michael@0: }
michael@0: 
michael@0: ThreadsafeAutoSafeJSContext::ThreadsafeAutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
michael@0: {
michael@0:   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
michael@0: 
michael@0:   if (NS_IsMainThread()) {
michael@0:     mCx = nullptr;
michael@0:     mAutoSafeJSContext.construct();
michael@0:   } else {
michael@0:     mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
michael@0:     mRequest.construct(mCx);
michael@0:   }
michael@0: }
michael@0: 
michael@0: ThreadsafeAutoSafeJSContext::operator JSContext*() const
michael@0: {
michael@0:   if (mCx) {
michael@0:     return mCx;
michael@0:   } else {
michael@0:     return mAutoSafeJSContext.ref();
michael@0:   }
michael@0: }
michael@0: 
michael@0: AutoPushJSContext::AutoPushJSContext(JSContext *aCx) : mCx(aCx)
michael@0: {
michael@0:   if (mCx && mCx != nsXPConnect::XPConnect()->GetCurrentJSContext()) {
michael@0:     mPusher.construct(mCx);
michael@0:   }
michael@0: }
michael@0: 
michael@0: } // namespace mozilla