gecko-dev/xpcom/threads/SchedulerGroup.h

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/* -*- 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/. */
#ifndef mozilla_SchedulerGroup_h
#define mozilla_SchedulerGroup_h
#include "mozilla/AbstractEventQueue.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Queue.h"
#include "mozilla/TaskCategory.h"
#include "mozilla/ThreadLocal.h"
#include "mozilla/TimeStamp.h"
#include "nsCOMPtr.h"
#include "nsISupportsImpl.h"
#include "nsThreadUtils.h"
class nsIEventTarget;
class nsIRunnable;
class nsISerialEventTarget;
namespace mozilla {
class AbstractThread;
namespace dom {
class DocGroup;
class TabGroup;
} // namespace dom
#define NS_SCHEDULERGROUPRUNNABLE_IID \
{ \
0xd31b7420, 0x872b, 0x4cfb, { \
0xa9, 0xc6, 0xae, 0x4c, 0x0f, 0x06, 0x36, 0x74 \
} \
}
// The "main thread" in Gecko will soon be a set of cooperatively scheduled
// "fibers". Global state in Gecko will be partitioned into a series of "groups"
// (with roughly one group per tab). Runnables will be annotated with the set of
// groups that they touch. Two runnables may run concurrently on different
// fibers as long as they touch different groups.
//
// A SchedulerGroup is an abstract class to represent a "group". Essentially the
// only functionality offered by a SchedulerGroup is the ability to dispatch
// runnables to the group. TabGroup, DocGroup, and SystemGroup are the concrete
// implementations of SchedulerGroup.
class SchedulerGroup : public LinkedListElement<SchedulerGroup> {
public:
SchedulerGroup();
NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
// This method returns true if all members of the "group" are in a
// "background" state.
virtual bool IsBackground() const { return false; }
// This function returns true if it's currently safe to run code associated
// with this SchedulerGroup. It will return true either if we're inside an
// unlabeled runnable or if we're inside a runnable labeled with this
// SchedulerGroup.
bool IsSafeToRun() const { return !sTlsValidatingAccess.get() || mIsRunning; }
// This function returns true if it's currently safe to run unlabeled code
// with no known SchedulerGroup. It will only return true if we're inside an
// unlabeled runnable.
static bool IsSafeToRunUnlabeled() { return !sTlsValidatingAccess.get(); }
// Ensure that it's valid to access the TabGroup at this time.
void ValidateAccess() const { MOZ_ASSERT(IsSafeToRun()); }
enum EnqueueStatus {
NewlyQueued,
AlreadyQueued,
};
// Records that this SchedulerGroup had an event enqueued in some
// queue. Returns whether the SchedulerGroup was already in a queue before
// EnqueueEvent() was called.
EnqueueStatus EnqueueEvent() {
mEventCount++;
return mEventCount == 1 ? NewlyQueued : AlreadyQueued;
}
enum DequeueStatus {
StillQueued,
NoLongerQueued,
};
// Records that this SchedulerGroup had an event dequeued from some
// queue. Returns whether the SchedulerGroup is still in a queue after
// DequeueEvent() returns.
DequeueStatus DequeueEvent() {
mEventCount--;
return mEventCount == 0 ? NoLongerQueued : StillQueued;
}
class Runnable final : public mozilla::Runnable, public nsIRunnablePriority {
public:
Runnable(already_AddRefed<nsIRunnable>&& aRunnable, SchedulerGroup* aGroup,
dom::DocGroup* aDocGroup);
SchedulerGroup* Group() const { return mGroup; }
dom::DocGroup* DocGroup() const;
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
NS_IMETHOD GetName(nsACString& aName) override;
#endif
bool IsBackground() const { return mGroup->IsBackground(); }
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_NSIRUNNABLE
NS_DECL_NSIRUNNABLEPRIORITY
NS_DECLARE_STATIC_IID_ACCESSOR(NS_SCHEDULERGROUPRUNNABLE_IID);
private:
friend class SchedulerGroup;
~Runnable() = default;
nsCOMPtr<nsIRunnable> mRunnable;
RefPtr<SchedulerGroup> mGroup;
RefPtr<dom::DocGroup> mDocGroup;
};
friend class Runnable;
bool* GetValidAccessPtr() { return &mIsRunning; }
virtual nsresult Dispatch(TaskCategory aCategory,
already_AddRefed<nsIRunnable>&& aRunnable);
virtual nsISerialEventTarget* EventTargetFor(TaskCategory aCategory) const;
// Must always be called on the main thread. The returned AbstractThread can
// always be used off the main thread.
AbstractThread* AbstractMainThreadFor(TaskCategory aCategory);
// This method performs a safe cast. It returns null if |this| is not of the
// requested type.
virtual dom::TabGroup* AsTabGroup() { return nullptr; }
static nsresult UnlabeledDispatch(TaskCategory aCategory,
already_AddRefed<nsIRunnable>&& aRunnable);
static void MarkVsyncReceived();
static void MarkVsyncRan();
void SetIsRunning(bool aIsRunning) { mIsRunning = aIsRunning; }
bool IsRunning() const { return mIsRunning; }
enum ValidationType {
StartValidation,
EndValidation,
};
static void SetValidatingAccess(ValidationType aType);
struct EpochQueueEntry {
nsCOMPtr<nsIRunnable> mRunnable;
uintptr_t mEpochNumber;
EpochQueueEntry(already_AddRefed<nsIRunnable> aRunnable, uintptr_t aEpoch)
: mRunnable(aRunnable), mEpochNumber(aEpoch) {}
};
using RunnableEpochQueue = Queue<EpochQueueEntry, 32>;
RunnableEpochQueue& GetQueue(mozilla::EventQueuePriority aPriority) {
return mEventQueues[size_t(aPriority)];
}
protected:
nsresult DispatchWithDocGroup(TaskCategory aCategory,
already_AddRefed<nsIRunnable>&& aRunnable,
dom::DocGroup* aDocGroup);
static nsresult InternalUnlabeledDispatch(
TaskCategory aCategory, already_AddRefed<Runnable>&& aRunnable);
// Implementations are guaranteed that this method is called on the main
// thread.
virtual AbstractThread* AbstractMainThreadForImpl(TaskCategory aCategory);
// Helper method to create an event target specific to a particular
// TaskCategory.
virtual already_AddRefed<nsISerialEventTarget> CreateEventTargetFor(
TaskCategory aCategory);
// Given an event target returned by |dispatcher->CreateEventTargetFor|, this
// function returns |dispatcher|.
static SchedulerGroup* FromEventTarget(nsIEventTarget* aEventTarget);
nsresult LabeledDispatch(TaskCategory aCategory,
already_AddRefed<nsIRunnable>&& aRunnable,
dom::DocGroup* aDocGroup);
void CreateEventTargets(bool aNeedValidation);
// Shuts down this dispatcher. If aXPCOMShutdown is true, invalidates this
// dispatcher.
void Shutdown(bool aXPCOMShutdown);
static MOZ_THREAD_LOCAL(bool) sTlsValidatingAccess;
bool mIsRunning;
// Number of events that are currently enqueued for this SchedulerGroup
// (across all queues).
size_t mEventCount = 0;
nsCOMPtr<nsISerialEventTarget> mEventTargets[size_t(TaskCategory::Count)];
RefPtr<AbstractThread> mAbstractThreads[size_t(TaskCategory::Count)];
RunnableEpochQueue mEventQueues[size_t(mozilla::EventQueuePriority::Count)];
};
NS_DEFINE_STATIC_IID_ACCESSOR(SchedulerGroup::Runnable,
NS_SCHEDULERGROUPRUNNABLE_IID);
} // namespace mozilla
#endif // mozilla_SchedulerGroup_h