gecko-dev/ipc/glue/MessagePump.cpp

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C++

/* 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 "MessagePump.h"
#include "nsIRunnable.h"
#include "nsIThread.h"
#include "nsITimer.h"
#include "nsICancelableRunnable.h"
#include "base/basictypes.h"
#include "base/logging.h"
#include "base/scoped_nsautorelease_pool.h"
#include "mozilla/Assertions.h"
#include "mozilla/DebugOnly.h"
#include "nsComponentManagerUtils.h"
#include "nsDebug.h"
#include "nsServiceManagerUtils.h"
#include "nsString.h"
#include "nsThreadUtils.h"
#include "nsTimerImpl.h"
#include "nsXULAppAPI.h"
#include "prthread.h"
#ifdef MOZ_NUWA_PROCESS
#include "ipc/Nuwa.h"
#endif
using base::TimeTicks;
using namespace mozilla::ipc;
NS_DEFINE_NAMED_CID(NS_TIMER_CID);
static mozilla::DebugOnly<MessagePump::Delegate*> gFirstDelegate;
namespace mozilla {
namespace ipc {
class DoWorkRunnable final : public nsICancelableRunnable,
public nsITimerCallback
{
public:
explicit DoWorkRunnable(MessagePump* aPump)
: mPump(aPump)
{
MOZ_ASSERT(aPump);
}
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIRUNNABLE
NS_DECL_NSITIMERCALLBACK
NS_DECL_NSICANCELABLERUNNABLE
private:
~DoWorkRunnable()
{ }
MessagePump* mPump;
// DoWorkRunnable is designed as a stateless singleton. Do not add stateful
// members here!
};
} /* namespace ipc */
} /* namespace mozilla */
MessagePump::MessagePump()
: mThread(nullptr)
{
mDoWorkEvent = new DoWorkRunnable(this);
}
MessagePump::~MessagePump()
{
}
void
MessagePump::Run(MessagePump::Delegate* aDelegate)
{
MOZ_ASSERT(keep_running_);
MOZ_ASSERT(NS_IsMainThread(),
"Use mozilla::ipc::MessagePumpForNonMainThreads instead!");
mThread = NS_GetCurrentThread();
MOZ_ASSERT(mThread);
mDelayedWorkTimer = do_CreateInstance(kNS_TIMER_CID);
MOZ_ASSERT(mDelayedWorkTimer);
base::ScopedNSAutoreleasePool autoReleasePool;
for (;;) {
autoReleasePool.Recycle();
bool did_work = NS_ProcessNextEvent(mThread, false) ? true : false;
if (!keep_running_)
break;
// NB: it is crucial *not* to directly call |aDelegate->DoWork()|
// here. To ensure that MessageLoop tasks and XPCOM events have
// equal priority, we sensitively rely on processing exactly one
// Task per DoWorkRunnable XPCOM event.
did_work |= aDelegate->DoDelayedWork(&delayed_work_time_);
if (did_work && delayed_work_time_.is_null()
#ifdef MOZ_NUWA_PROCESS
&& (!IsNuwaReady() || !IsNuwaProcess())
#endif
)
mDelayedWorkTimer->Cancel();
if (!keep_running_)
break;
if (did_work)
continue;
did_work = aDelegate->DoIdleWork();
if (!keep_running_)
break;
if (did_work)
continue;
// This will either sleep or process an event.
NS_ProcessNextEvent(mThread, true);
}
#ifdef MOZ_NUWA_PROCESS
if (!IsNuwaReady() || !IsNuwaProcess())
#endif
mDelayedWorkTimer->Cancel();
keep_running_ = true;
}
void
MessagePump::ScheduleWork()
{
// Make sure the event loop wakes up.
if (mThread) {
mThread->Dispatch(mDoWorkEvent, NS_DISPATCH_NORMAL);
}
else {
// Some things (like xpcshell) don't use the app shell and so Run hasn't
// been called. We still need to wake up the main thread.
NS_DispatchToMainThread(mDoWorkEvent);
}
event_.Signal();
}
void
MessagePump::ScheduleWorkForNestedLoop()
{
// This method is called when our MessageLoop has just allowed
// nested tasks. In our setup, whenever that happens we know that
// DoWork() will be called "soon", so there's no need to pay the
// cost of what will be a no-op nsThread::Dispatch(mDoWorkEvent).
}
void
MessagePump::ScheduleDelayedWork(const base::TimeTicks& aDelayedTime)
{
#ifdef MOZ_NUWA_PROCESS
if (IsNuwaReady() && IsNuwaProcess())
return;
#endif
if (!mDelayedWorkTimer) {
mDelayedWorkTimer = do_CreateInstance(kNS_TIMER_CID);
if (!mDelayedWorkTimer) {
// Called before XPCOM has started up? We can't do this correctly.
NS_WARNING("Delayed task might not run!");
delayed_work_time_ = aDelayedTime;
return;
}
}
if (!delayed_work_time_.is_null()) {
mDelayedWorkTimer->Cancel();
}
delayed_work_time_ = aDelayedTime;
// TimeDelta's constructor initializes to 0
base::TimeDelta delay;
if (aDelayedTime > base::TimeTicks::Now())
delay = aDelayedTime - base::TimeTicks::Now();
uint32_t delayMS = uint32_t(delay.InMilliseconds());
mDelayedWorkTimer->InitWithCallback(mDoWorkEvent, delayMS,
nsITimer::TYPE_ONE_SHOT);
}
void
MessagePump::DoDelayedWork(base::MessagePump::Delegate* aDelegate)
{
aDelegate->DoDelayedWork(&delayed_work_time_);
if (!delayed_work_time_.is_null()) {
ScheduleDelayedWork(delayed_work_time_);
}
}
NS_IMPL_ISUPPORTS(DoWorkRunnable, nsIRunnable, nsITimerCallback,
nsICancelableRunnable)
NS_IMETHODIMP
DoWorkRunnable::Run()
{
MessageLoop* loop = MessageLoop::current();
MOZ_ASSERT(loop);
bool nestableTasksAllowed = loop->NestableTasksAllowed();
// MessageLoop::RunTask() disallows nesting, but our Frankenventloop will
// always dispatch DoWork() below from what looks to MessageLoop like a nested
// context. So we unconditionally allow nesting here.
loop->SetNestableTasksAllowed(true);
loop->DoWork();
loop->SetNestableTasksAllowed(nestableTasksAllowed);
return NS_OK;
}
NS_IMETHODIMP
DoWorkRunnable::Notify(nsITimer* aTimer)
{
MessageLoop* loop = MessageLoop::current();
MOZ_ASSERT(loop);
mPump->DoDelayedWork(loop);
return NS_OK;
}
NS_IMETHODIMP
DoWorkRunnable::Cancel()
{
// Workers require cancelable runnables, but we can't really cancel cleanly
// here. If we don't process this runnable then we will leave something
// unprocessed in the message_loop. Therefore, eagerly complete our work
// instead by immediately calling Run(). Run() should be called separately
// after this. Unfortunately we cannot use flags to verify this because
// DoWorkRunnable is a stateless singleton that can be in the event queue
// multiple times simultaneously.
MOZ_ALWAYS_TRUE(NS_SUCCEEDED(Run()));
return NS_OK;
}
void
MessagePumpForChildProcess::Run(base::MessagePump::Delegate* aDelegate)
{
if (mFirstRun) {
MOZ_ASSERT(aDelegate && !gFirstDelegate);
gFirstDelegate = aDelegate;
mFirstRun = false;
if (NS_FAILED(XRE_RunAppShell())) {
NS_WARNING("Failed to run app shell?!");
}
MOZ_ASSERT(aDelegate && aDelegate == gFirstDelegate);
gFirstDelegate = nullptr;
return;
}
MOZ_ASSERT(aDelegate && aDelegate == gFirstDelegate);
// We can get to this point in startup with Tasks in our loop's
// incoming_queue_ or pending_queue_, but without a matching
// DoWorkRunnable(). In MessagePump::Run() above, we sensitively
// depend on *not* directly calling delegate->DoWork(), because that
// prioritizes Tasks above XPCOM events. However, from this point
// forward, any Task posted to our loop is guaranteed to have a
// DoWorkRunnable enqueued for it.
//
// So we just flush the pending work here and move on.
MessageLoop* loop = MessageLoop::current();
bool nestableTasksAllowed = loop->NestableTasksAllowed();
loop->SetNestableTasksAllowed(true);
while (aDelegate->DoWork());
loop->SetNestableTasksAllowed(nestableTasksAllowed);
// Really run.
mozilla::ipc::MessagePump::Run(aDelegate);
}
void
MessagePumpForNonMainThreads::Run(base::MessagePump::Delegate* aDelegate)
{
MOZ_ASSERT(keep_running_);
MOZ_ASSERT(!NS_IsMainThread(), "Use mozilla::ipc::MessagePump instead!");
mThread = NS_GetCurrentThread();
MOZ_ASSERT(mThread);
mDelayedWorkTimer = do_CreateInstance(kNS_TIMER_CID);
MOZ_ASSERT(mDelayedWorkTimer);
if (NS_FAILED(mDelayedWorkTimer->SetTarget(mThread))) {
MOZ_CRASH("Failed to set timer target!");
}
// Chromium event notifications to be processed will be received by this
// event loop as a DoWorkRunnables via ScheduleWork. Chromium events that
// were received before our mThread is valid, however, will not generate
// runnable wrappers. We must process any of these before we enter this
// loop, or we will forever have unprocessed chromium messages in our queue.
//
// Note we would like to request a flush of the chromium event queue
// using a runnable on the xpcom side, but some thread implementations
// (dom workers) get cranky if we call ScheduleWork here (ScheduleWork
// calls dispatch on mThread) before the thread processes an event. As
// such, clear the queue manually.
while (aDelegate->DoWork()) {
}
base::ScopedNSAutoreleasePool autoReleasePool;
for (;;) {
autoReleasePool.Recycle();
bool didWork = NS_ProcessNextEvent(mThread, false) ? true : false;
if (!keep_running_) {
break;
}
didWork |= aDelegate->DoDelayedWork(&delayed_work_time_);
if (didWork && delayed_work_time_.is_null()) {
mDelayedWorkTimer->Cancel();
}
if (!keep_running_) {
break;
}
if (didWork) {
continue;
}
didWork = aDelegate->DoIdleWork();
if (!keep_running_) {
break;
}
if (didWork) {
continue;
}
// This will either sleep or process an event.
NS_ProcessNextEvent(mThread, true);
}
mDelayedWorkTimer->Cancel();
keep_running_ = true;
}
#if defined(XP_WIN)
NS_IMPL_QUERY_INTERFACE(MessagePumpForNonMainUIThreads, nsIThreadObserver)
#define CHECK_QUIT_STATE { if (state_->should_quit) { break; } }
void MessagePumpForNonMainUIThreads::DoRunLoop()
{
// If this is a chromium thread and no nsThread is associated
// with it, this call will create a new nsThread.
mThread = NS_GetCurrentThread();
MOZ_ASSERT(mThread);
// Set the main thread observer so we can wake up when
// xpcom events need to get processed.
nsCOMPtr<nsIThreadInternal> ti(do_QueryInterface(mThread));
MOZ_ASSERT(ti);
ti->SetObserver(this);
base::ScopedNSAutoreleasePool autoReleasePool;
for (;;) {
autoReleasePool.Recycle();
bool didWork = NS_ProcessNextEvent(mThread, false);
didWork |= ProcessNextWindowsMessage();
CHECK_QUIT_STATE
didWork |= state_->delegate->DoWork();
CHECK_QUIT_STATE
didWork |= state_->delegate->DoDelayedWork(&delayed_work_time_);
if (didWork && delayed_work_time_.is_null()) {
KillTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this));
}
CHECK_QUIT_STATE
if (didWork) {
continue;
}
didWork = state_->delegate->DoIdleWork();
CHECK_QUIT_STATE
SetInWait();
bool hasWork = NS_HasPendingEvents(mThread);
if (didWork || hasWork) {
ClearInWait();
continue;
}
WaitForWork(); // Calls MsgWaitForMultipleObjectsEx(QS_ALLINPUT)
ClearInWait();
}
ClearInWait();
ti->SetObserver(nullptr);
}
NS_IMETHODIMP
MessagePumpForNonMainUIThreads::OnDispatchedEvent(nsIThreadInternal *thread)
{
// If our thread is sleeping in DoRunLoop's call to WaitForWork() and an
// event posts to the nsIThread event queue - break our thread out of
// chromium's WaitForWork.
if (GetInWait()) {
ScheduleWork();
}
return NS_OK;
}
NS_IMETHODIMP
MessagePumpForNonMainUIThreads::OnProcessNextEvent(nsIThreadInternal *thread,
bool mayWait)
{
return NS_OK;
}
NS_IMETHODIMP
MessagePumpForNonMainUIThreads::AfterProcessNextEvent(nsIThreadInternal *thread,
bool eventWasProcessed)
{
return NS_OK;
}
#endif // XP_WIN