1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/xpconnect/src/nsCxPusher.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,264 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "nsCxPusher.h"
1.11 +
1.12 +#include "nsIScriptContext.h"
1.13 +#include "mozilla/dom/EventTarget.h"
1.14 +#include "nsDOMJSUtils.h"
1.15 +#include "xpcprivate.h"
1.16 +#include "WorkerPrivate.h"
1.17 +
1.18 +using mozilla::dom::EventTarget;
1.19 +using mozilla::DebugOnly;
1.20 +
1.21 +bool
1.22 +nsCxPusher::Push(EventTarget *aCurrentTarget)
1.23 +{
1.24 + MOZ_ASSERT(mPusher.empty());
1.25 + NS_ENSURE_TRUE(aCurrentTarget, false);
1.26 + nsresult rv;
1.27 + nsIScriptContext* scx =
1.28 + aCurrentTarget->GetContextForEventHandlers(&rv);
1.29 +#ifdef DEBUG_smaug
1.30 + NS_ENSURE_SUCCESS(rv, false);
1.31 +#else
1.32 + if(NS_FAILED(rv)) {
1.33 + return false;
1.34 + }
1.35 +#endif
1.36 +
1.37 + if (!scx) {
1.38 + // The target may have a special JS context for event handlers.
1.39 + JSContext* cx = aCurrentTarget->GetJSContextForEventHandlers();
1.40 + if (cx) {
1.41 + mPusher.construct(cx);
1.42 + }
1.43 +
1.44 + // Nothing to do here, I guess. Have to return true so that event firing
1.45 + // will still work correctly even if there is no associated JSContext
1.46 + return true;
1.47 + }
1.48 +
1.49 + mPusher.construct(scx->GetNativeContext());
1.50 + return true;
1.51 +}
1.52 +
1.53 +bool
1.54 +nsCxPusher::RePush(EventTarget *aCurrentTarget)
1.55 +{
1.56 + if (mPusher.empty()) {
1.57 + return Push(aCurrentTarget);
1.58 + }
1.59 +
1.60 + if (aCurrentTarget) {
1.61 + nsresult rv;
1.62 + nsIScriptContext* scx =
1.63 + aCurrentTarget->GetContextForEventHandlers(&rv);
1.64 + if (NS_FAILED(rv)) {
1.65 + mPusher.destroy();
1.66 + return false;
1.67 + }
1.68 +
1.69 + // If we have the same script context and native context is still
1.70 + // alive, no need to Pop/Push.
1.71 + if (scx && scx == mPusher.ref().GetScriptContext() &&
1.72 + scx->GetNativeContext()) {
1.73 + return true;
1.74 + }
1.75 + }
1.76 +
1.77 + mPusher.destroy();
1.78 + return Push(aCurrentTarget);
1.79 +}
1.80 +
1.81 +void
1.82 +nsCxPusher::Push(JSContext *cx)
1.83 +{
1.84 + mPusher.construct(cx);
1.85 +}
1.86 +
1.87 +void
1.88 +nsCxPusher::PushNull()
1.89 +{
1.90 + // Note: The Maybe<> template magic seems to need the static_cast below to
1.91 + // work right on some older compilers.
1.92 + mPusher.construct(static_cast<JSContext*>(nullptr), /* aAllowNull = */ true);
1.93 +}
1.94 +
1.95 +void
1.96 +nsCxPusher::Pop()
1.97 +{
1.98 + if (!mPusher.empty())
1.99 + mPusher.destroy();
1.100 +}
1.101 +
1.102 +namespace mozilla {
1.103 +
1.104 +AutoCxPusher::AutoCxPusher(JSContext* cx, bool allowNull)
1.105 +{
1.106 + MOZ_ASSERT_IF(!allowNull, cx);
1.107 +
1.108 + // Hold a strong ref to the nsIScriptContext, if any. This ensures that we
1.109 + // only destroy the mContext of an nsJSContext when it is not on the cx stack
1.110 + // (and therefore not in use). See nsJSContext::DestroyJSContext().
1.111 + if (cx)
1.112 + mScx = GetScriptContextFromJSContext(cx);
1.113 +
1.114 + XPCJSContextStack *stack = XPCJSRuntime::Get()->GetJSContextStack();
1.115 + if (!stack->Push(cx)) {
1.116 + MOZ_CRASH();
1.117 + }
1.118 + mStackDepthAfterPush = stack->Count();
1.119 +
1.120 +#ifdef DEBUG
1.121 + mPushedContext = cx;
1.122 + mCompartmentDepthOnEntry = cx ? js::GetEnterCompartmentDepth(cx) : 0;
1.123 +#endif
1.124 +
1.125 + // Enter a request and a compartment for the duration that the cx is on the
1.126 + // stack if non-null.
1.127 + if (cx) {
1.128 + mAutoRequest.construct(cx);
1.129 +
1.130 + // DOM JSContexts don't store their default compartment object on the cx.
1.131 + JSObject *compartmentObject = mScx ? mScx->GetWindowProxy()
1.132 + : js::DefaultObjectForContextOrNull(cx);
1.133 + if (compartmentObject)
1.134 + mAutoCompartment.construct(cx, compartmentObject);
1.135 + }
1.136 +}
1.137 +
1.138 +AutoCxPusher::~AutoCxPusher()
1.139 +{
1.140 + // GC when we pop a script entry point. This is a useful heuristic that helps
1.141 + // us out on certain (flawed) benchmarks like sunspider, because it lets us
1.142 + // avoid GCing during the timing loop.
1.143 + //
1.144 + // NB: We need to take care to only do this if we're in a compartment,
1.145 + // otherwise JS_MaybeGC will segfault.
1.146 + if (mScx && !mAutoCompartment.empty())
1.147 + JS_MaybeGC(nsXPConnect::XPConnect()->GetCurrentJSContext());
1.148 +
1.149 + // Leave the compartment and request before popping.
1.150 + mAutoCompartment.destroyIfConstructed();
1.151 + mAutoRequest.destroyIfConstructed();
1.152 +
1.153 + // When we push a context, we may save the frame chain and pretend like we
1.154 + // haven't entered any compartment. This gets restored on Pop(), but we can
1.155 + // run into trouble if a Push/Pop are interleaved with a
1.156 + // JSAutoEnterCompartment. Make sure the compartment depth right before we
1.157 + // pop is the same as it was right after we pushed.
1.158 + MOZ_ASSERT_IF(mPushedContext, mCompartmentDepthOnEntry ==
1.159 + js::GetEnterCompartmentDepth(mPushedContext));
1.160 + DebugOnly<JSContext*> stackTop;
1.161 + MOZ_ASSERT(mPushedContext == nsXPConnect::XPConnect()->GetCurrentJSContext());
1.162 + XPCJSRuntime::Get()->GetJSContextStack()->Pop();
1.163 + mScx = nullptr;
1.164 +}
1.165 +
1.166 +bool
1.167 +AutoCxPusher::IsStackTop()
1.168 +{
1.169 + uint32_t currentDepth = XPCJSRuntime::Get()->GetJSContextStack()->Count();
1.170 + MOZ_ASSERT(currentDepth >= mStackDepthAfterPush);
1.171 + return currentDepth == mStackDepthAfterPush;
1.172 +}
1.173 +
1.174 +AutoJSContext::AutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
1.175 + : mCx(nullptr)
1.176 +{
1.177 + Init(false MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
1.178 +}
1.179 +
1.180 +AutoJSContext::AutoJSContext(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
1.181 + : mCx(nullptr)
1.182 +{
1.183 + Init(aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT);
1.184 +}
1.185 +
1.186 +void
1.187 +AutoJSContext::Init(bool aSafe MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
1.188 +{
1.189 + JS::AutoAssertNoGC nogc;
1.190 + MOZ_ASSERT(!mCx, "mCx should not be initialized!");
1.191 +
1.192 + MOZ_GUARD_OBJECT_NOTIFIER_INIT;
1.193 +
1.194 + nsXPConnect *xpc = nsXPConnect::XPConnect();
1.195 + if (!aSafe) {
1.196 + mCx = xpc->GetCurrentJSContext();
1.197 + }
1.198 +
1.199 + if (!mCx) {
1.200 + mCx = xpc->GetSafeJSContext();
1.201 + mPusher.construct(mCx);
1.202 + }
1.203 +}
1.204 +
1.205 +AutoJSContext::operator JSContext*() const
1.206 +{
1.207 + return mCx;
1.208 +}
1.209 +
1.210 +ThreadsafeAutoJSContext::ThreadsafeAutoJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
1.211 +{
1.212 + MOZ_GUARD_OBJECT_NOTIFIER_INIT;
1.213 +
1.214 + if (NS_IsMainThread()) {
1.215 + mCx = nullptr;
1.216 + mAutoJSContext.construct();
1.217 + } else {
1.218 + mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
1.219 + mRequest.construct(mCx);
1.220 + }
1.221 +}
1.222 +
1.223 +ThreadsafeAutoJSContext::operator JSContext*() const
1.224 +{
1.225 + if (mCx) {
1.226 + return mCx;
1.227 + } else {
1.228 + return mAutoJSContext.ref();
1.229 + }
1.230 +}
1.231 +
1.232 +AutoSafeJSContext::AutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
1.233 + : AutoJSContext(true MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
1.234 + , mAc(mCx, XPCJSRuntime::Get()->GetJSContextStack()->GetSafeJSContextGlobal())
1.235 +{
1.236 +}
1.237 +
1.238 +ThreadsafeAutoSafeJSContext::ThreadsafeAutoSafeJSContext(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_IN_IMPL)
1.239 +{
1.240 + MOZ_GUARD_OBJECT_NOTIFIER_INIT;
1.241 +
1.242 + if (NS_IsMainThread()) {
1.243 + mCx = nullptr;
1.244 + mAutoSafeJSContext.construct();
1.245 + } else {
1.246 + mCx = mozilla::dom::workers::GetCurrentThreadJSContext();
1.247 + mRequest.construct(mCx);
1.248 + }
1.249 +}
1.250 +
1.251 +ThreadsafeAutoSafeJSContext::operator JSContext*() const
1.252 +{
1.253 + if (mCx) {
1.254 + return mCx;
1.255 + } else {
1.256 + return mAutoSafeJSContext.ref();
1.257 + }
1.258 +}
1.259 +
1.260 +AutoPushJSContext::AutoPushJSContext(JSContext *aCx) : mCx(aCx)
1.261 +{
1.262 + if (mCx && mCx != nsXPConnect::XPConnect()->GetCurrentJSContext()) {
1.263 + mPusher.construct(mCx);
1.264 + }
1.265 +}
1.266 +
1.267 +} // namespace mozilla
