gecko-dev/xpcom/threads/nsThreadUtils.h

1818 lines
60 KiB
C++

/* -*- 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 nsThreadUtils_h__
#define nsThreadUtils_h__
#include "prthread.h"
#include "prinrval.h"
#include "MainThreadUtils.h"
#include "nsICancelableRunnable.h"
#include "nsIIdlePeriod.h"
#include "nsIIdleRunnable.h"
#include "nsINamed.h"
#include "nsIRunnable.h"
#include "nsIThreadManager.h"
#include "nsITimer.h"
#include "nsIThread.h"
#include "nsString.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include "mozilla/Atomics.h"
#include "mozilla/Likely.h"
#include "mozilla/Move.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/Tuple.h"
#include "mozilla/TypeTraits.h"
#include <utility>
//-----------------------------------------------------------------------------
// These methods are alternatives to the methods on nsIThreadManager, provided
// for convenience.
/**
* Create a new thread, and optionally provide an initial event for the thread.
*
* @param aResult
* The resulting nsIThread object.
* @param aInitialEvent
* The initial event to run on this thread. This parameter may be null.
* @param aStackSize
* The size in bytes to reserve for the thread's stack.
*
* @returns NS_ERROR_INVALID_ARG
* Indicates that the given name is not unique.
*/
extern nsresult
NS_NewThread(nsIThread** aResult,
nsIRunnable* aInitialEvent = nullptr,
uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
/**
* Creates a named thread, otherwise the same as NS_NewThread
*/
extern nsresult
NS_NewNamedThread(const nsACString& aName,
nsIThread** aResult,
nsIRunnable* aInitialEvent = nullptr,
uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
template<size_t LEN>
inline nsresult
NS_NewNamedThread(const char (&aName)[LEN],
nsIThread** aResult,
nsIRunnable* aInitialEvent = nullptr,
uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE)
{
static_assert(LEN <= 16,
"Thread name must be no more than 16 characters");
return NS_NewNamedThread(nsDependentCString(aName, LEN - 1),
aResult, aInitialEvent, aStackSize);
}
/**
* Get a reference to the current thread, creating it if it does not exist yet.
*
* @param aResult
* The resulting nsIThread object.
*/
extern nsresult NS_GetCurrentThread(nsIThread** aResult);
/**
* Dispatch the given event to the current thread.
*
* @param aEvent
* The event to dispatch.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
*/
extern nsresult NS_DispatchToCurrentThread(nsIRunnable* aEvent);
extern nsresult
NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
/**
* Dispatch the given event to the main thread.
*
* @param aEvent
* The event to dispatch.
* @param aDispatchFlags
* The flags to pass to the main thread's dispatch method.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
*/
extern nsresult
NS_DispatchToMainThread(nsIRunnable* aEvent,
uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
extern nsresult
NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent,
uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
extern nsresult
NS_DelayedDispatchToCurrentThread(
already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs);
/**
* Dispatch the given event to the idle queue of the current thread.
*
* @param aEvent
* The event to dispatch.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
* @returns NS_ERROR_UNEXPECTED
* If the thread is shutting down.
*/
extern nsresult
NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
/**
* Dispatch the given event to the idle queue of the current thread.
*
* @param aEvent The event to dispatch. If the event implements
* nsIIdleRunnable, it will receive a call on
* nsIIdleRunnable::SetTimer when dispatched, with the value of
* aTimeout.
*
* @param aTimeout The time in milliseconds until the event should be
* moved from the idle queue to the regular queue, if it hasn't been
* executed. If aEvent is also an nsIIdleRunnable, it is expected
* that it should handle the timeout itself, after a call to
* nsIIdleRunnable::SetTimer.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
* @returns NS_ERROR_UNEXPECTED
* If the thread is shutting down.
*/
extern nsresult
NS_IdleDispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aTimeout);
/**
* Dispatch the given event to the idle queue of a thread.
*
* @param aEvent The event to dispatch.
*
* @param aThread The target thread for the dispatch.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
* @returns NS_ERROR_UNEXPECTED
* If the thread is shutting down.
*/
extern nsresult
NS_IdleDispatchToThread(already_AddRefed<nsIRunnable>&& aEvent,
nsIThread* aThread);
/**
* Dispatch the given event to the idle queue of a thread.
*
* @param aEvent The event to dispatch. If the event implements
* nsIIdleRunnable, it will receive a call on
* nsIIdleRunnable::SetTimer when dispatched, with the value of
* aTimeout.
*
* @param aTimeout The time in milliseconds until the event should be
* moved from the idle queue to the regular queue, if it hasn't been
* executed. If aEvent is also an nsIIdleRunnable, it is expected
* that it should handle the timeout itself, after a call to
* nsIIdleRunnable::SetTimer.
*
* @param aThread The target thread for the dispatch.
*
* @returns NS_ERROR_INVALID_ARG
* If event is null.
* @returns NS_ERROR_UNEXPECTED
* If the thread is shutting down.
*/
extern nsresult
NS_IdleDispatchToThread(already_AddRefed<nsIRunnable>&& aEvent,
uint32_t aTimeout,
nsIThread* aThread);
#ifndef XPCOM_GLUE_AVOID_NSPR
/**
* Process all pending events for the given thread before returning. This
* method simply calls ProcessNextEvent on the thread while HasPendingEvents
* continues to return true and the time spent in NS_ProcessPendingEvents
* does not exceed the given timeout value.
*
* @param aThread
* The thread object for which to process pending events. If null, then
* events will be processed for the current thread.
* @param aTimeout
* The maximum number of milliseconds to spend processing pending events.
* Events are not pre-empted to honor this timeout. Rather, the timeout
* value is simply used to determine whether or not to process another event.
* Pass PR_INTERVAL_NO_TIMEOUT to specify no timeout.
*/
extern nsresult
NS_ProcessPendingEvents(nsIThread* aThread,
PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT);
#endif
/**
* Shortcut for nsIThread::HasPendingEvents.
*
* It is an error to call this function when the given thread is not the
* current thread. This function will return false if called from some
* other thread.
*
* @param aThread
* The current thread or null.
*
* @returns
* A boolean value that if "true" indicates that there are pending events
* in the current thread's event queue.
*/
extern bool NS_HasPendingEvents(nsIThread* aThread = nullptr);
/**
* Shortcut for nsIThread::ProcessNextEvent.
*
* It is an error to call this function when the given thread is not the
* current thread. This function will simply return false if called
* from some other thread.
*
* @param aThread
* The current thread or null.
* @param aMayWait
* A boolean parameter that if "true" indicates that the method may block
* the calling thread to wait for a pending event.
*
* @returns
* A boolean value that if "true" indicates that an event from the current
* thread's event queue was processed.
*/
extern bool NS_ProcessNextEvent(nsIThread* aThread = nullptr,
bool aMayWait = true);
// A wrapper for nested event loops.
//
// This function is intended to make code more obvious (do you remember
// what NS_ProcessNextEvent(nullptr, true) means?) and slightly more
// efficient, as people often pass nullptr or NS_GetCurrentThread to
// NS_ProcessNextEvent, which results in needless querying of the current
// thread every time through the loop.
//
// You should use this function in preference to NS_ProcessNextEvent inside
// a loop unless one of the following is true:
//
// * You need to pass `false` to NS_ProcessNextEvent; or
// * You need to do unusual things around the call to NS_ProcessNextEvent,
// such as unlocking mutexes that you are holding.
//
// If you *do* need to call NS_ProcessNextEvent manually, please do call
// NS_GetCurrentThread() outside of your loop and pass the returned pointer
// into NS_ProcessNextEvent for a tiny efficiency win.
namespace mozilla {
// You should normally not need to deal with this template parameter. If
// you enjoy esoteric event loop details, read on.
//
// If you specify that NS_ProcessNextEvent wait for an event, it is possible
// for NS_ProcessNextEvent to return false, i.e. to indicate that an event
// was not processed. This can only happen when the thread has been shut
// down by another thread, but is still attempting to process events outside
// of a nested event loop.
//
// This behavior is admittedly strange. The scenario it deals with is the
// following:
//
// * The current thread has been shut down by some owner thread.
// * The current thread is spinning an event loop waiting for some condition
// to become true.
// * Said condition is actually being fulfilled by another thread, so there
// are timing issues in play.
//
// Thus, there is a small window where the current thread's event loop
// spinning can check the condition, find it false, and call
// NS_ProcessNextEvent to wait for another event. But we don't actually
// want it to wait indefinitely, because there might not be any other events
// in the event loop, and the current thread can't accept dispatched events
// because it's being shut down. Thus, actually blocking would hang the
// thread, which is bad. The solution, then, is to detect such a scenario
// and not actually block inside NS_ProcessNextEvent.
//
// But this is a problem, because we want to return the status of
// NS_ProcessNextEvent to the caller of SpinEventLoopUntil if possible. In
// the above scenario, however, we'd stop spinning prematurely and cause
// all sorts of havoc. We therefore have this template parameter to
// control whether errors are ignored or passed out to the caller of
// SpinEventLoopUntil. The latter is the default; if you find yourself
// wanting to use the former, you should think long and hard before doing
// so, and write a comment like this defending your choice.
enum class ProcessFailureBehavior {
IgnoreAndContinue,
ReportToCaller,
};
template<ProcessFailureBehavior Behavior = ProcessFailureBehavior::ReportToCaller,
typename Pred>
bool
SpinEventLoopUntil(Pred&& aPredicate, nsIThread* aThread = nullptr)
{
nsIThread* thread = aThread ? aThread : NS_GetCurrentThread();
while (!aPredicate()) {
bool didSomething = NS_ProcessNextEvent(thread, true);
if (Behavior == ProcessFailureBehavior::IgnoreAndContinue) {
// Don't care what happened, continue on.
continue;
} else if (!didSomething) {
return false;
}
}
return true;
}
} // namespace mozilla
/**
* Returns true if we're in the compositor thread.
*
* We declare this here because the headers required to invoke
* CompositorThreadHolder::IsInCompositorThread() also pull in a bunch of system
* headers that #define various tokens in a way that can break the build.
*/
extern bool NS_IsInCompositorThread();
extern bool NS_IsInVRThread();
//-----------------------------------------------------------------------------
// Helpers that work with nsCOMPtr:
inline already_AddRefed<nsIThread>
do_GetCurrentThread()
{
nsIThread* thread = nullptr;
NS_GetCurrentThread(&thread);
return already_AddRefed<nsIThread>(thread);
}
inline already_AddRefed<nsIThread>
do_GetMainThread()
{
nsIThread* thread = nullptr;
NS_GetMainThread(&thread);
return already_AddRefed<nsIThread>(thread);
}
//-----------------------------------------------------------------------------
#ifdef MOZILLA_INTERNAL_API
// Fast access to the current thread. Will create an nsIThread if one does not
// exist already! Do not release the returned pointer! If you want to use this
// pointer from some other thread, then you will need to AddRef it. Otherwise,
// you should only consider this pointer valid from code running on the current
// thread.
extern nsIThread* NS_GetCurrentThread();
// Exactly the same as NS_GetCurrentThread, except it will not create an
// nsThread if one does not exist yet. This is useful in cases where you have
// code that runs on threads that may or may not not be driven by an nsThread
// event loop, and wish to avoid inadvertently creating a superfluous nsThread.
extern nsIThread* NS_GetCurrentThreadNoCreate();
/**
* Set the name of the current thread. Prefer this function over
* PR_SetCurrentThreadName() if possible. The name will also be included in the
* crash report.
*
* @param aName
* Name of the thread. A C language null-terminated string.
*/
extern void NS_SetCurrentThreadName(const char* aName);
#endif
//-----------------------------------------------------------------------------
#ifndef XPCOM_GLUE_AVOID_NSPR
namespace mozilla {
// This class is designed to be subclassed.
class IdlePeriod : public nsIIdlePeriod
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIIDLEPERIOD
IdlePeriod() {}
protected:
virtual ~IdlePeriod() {}
private:
IdlePeriod(const IdlePeriod&) = delete;
IdlePeriod& operator=(const IdlePeriod&) = delete;
IdlePeriod& operator=(const IdlePeriod&&) = delete;
};
// Cancelable runnable methods implement nsICancelableRunnable, and
// Idle and IdleWithTimer also nsIIdleRunnable.
enum RunnableKind
{
Standard,
Cancelable,
Idle,
IdleWithTimer
};
// Implementing nsINamed on Runnable bloats vtables for the hundreds of
// Runnable subclasses that we have, so we want to avoid that overhead
// when we're not using nsINamed for anything.
#ifndef RELEASE_OR_BETA
#define MOZ_COLLECTING_RUNNABLE_TELEMETRY
#endif
// This class is designed to be subclassed.
class Runnable
: public nsIRunnable
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
, public nsINamed
#endif
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIRUNNABLE
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
NS_DECL_NSINAMED
#endif
Runnable() = delete;
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
explicit Runnable(const char* aName) : mName(aName) {}
#else
explicit Runnable(const char* aName) {}
#endif
protected:
virtual ~Runnable() {}
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
const char* mName = nullptr;
#endif
private:
Runnable(const Runnable&) = delete;
Runnable& operator=(const Runnable&) = delete;
Runnable& operator=(const Runnable&&) = delete;
};
// This class is designed to be subclassed.
class CancelableRunnable : public Runnable,
public nsICancelableRunnable
{
public:
NS_DECL_ISUPPORTS_INHERITED
// nsICancelableRunnable
virtual nsresult Cancel() override;
CancelableRunnable() = delete;
explicit CancelableRunnable(const char* aName) : Runnable(aName) {}
protected:
virtual ~CancelableRunnable() {}
private:
CancelableRunnable(const CancelableRunnable&) = delete;
CancelableRunnable& operator=(const CancelableRunnable&) = delete;
CancelableRunnable& operator=(const CancelableRunnable&&) = delete;
};
// This class is designed to be subclassed.
class IdleRunnable : public CancelableRunnable,
public nsIIdleRunnable
{
public:
NS_DECL_ISUPPORTS_INHERITED
IdleRunnable()
: CancelableRunnable("IdleRunnable")
{
}
explicit IdleRunnable(const char* aName) : CancelableRunnable(aName) {}
protected:
virtual ~IdleRunnable() {}
private:
IdleRunnable(const IdleRunnable&) = delete;
IdleRunnable& operator=(const IdleRunnable&) = delete;
IdleRunnable& operator=(const IdleRunnable&&) = delete;
};
// This class is designed to be a wrapper of a real runnable to support event
// prioritizable.
class PrioritizableRunnable : public Runnable, public nsIRunnablePriority
{
public:
PrioritizableRunnable(already_AddRefed<nsIRunnable>&& aRunnable,
uint32_t aPriority);
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
NS_IMETHOD GetName(nsACString& aName) override;
#endif
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_NSIRUNNABLE
NS_DECL_NSIRUNNABLEPRIORITY
protected:
virtual ~PrioritizableRunnable() {};
nsCOMPtr<nsIRunnable> mRunnable;
uint32_t mPriority;
};
namespace detail {
// An event that can be used to call a C++11 functions or function objects,
// including lambdas. The function must have no required arguments, and must
// return void.
template<typename StoredFunction>
class RunnableFunction : public Runnable
{
public:
template <typename F>
explicit RunnableFunction(const char* aName, F&& aFunction)
: Runnable(aName)
, mFunction(Forward<F>(aFunction))
{ }
NS_IMETHOD Run() override {
static_assert(IsVoid<decltype(mFunction())>::value,
"The lambda must return void!");
mFunction();
return NS_OK;
}
private:
StoredFunction mFunction;
};
// Type alias for NS_NewRunnableFunction
template<typename Function>
using RunnableFunctionImpl =
// Make sure we store a non-reference in nsRunnableFunction.
typename detail::RunnableFunction<typename RemoveReference<Function>::Type>;
} // namespace detail
namespace detail {
template<typename CVRemoved>
struct IsRefcountedSmartPointerHelper : FalseType {};
template<typename Pointee>
struct IsRefcountedSmartPointerHelper<RefPtr<Pointee>> : TrueType {};
template<typename Pointee>
struct IsRefcountedSmartPointerHelper<nsCOMPtr<Pointee>> : TrueType {};
} // namespace detail
template<typename T>
struct IsRefcountedSmartPointer
: detail::IsRefcountedSmartPointerHelper<typename RemoveCV<T>::Type>
{};
namespace detail {
template<typename T, typename CVRemoved>
struct RemoveSmartPointerHelper
{
typedef T Type;
};
template<typename T, typename Pointee>
struct RemoveSmartPointerHelper<T, RefPtr<Pointee>>
{
typedef Pointee Type;
};
template<typename T, typename Pointee>
struct RemoveSmartPointerHelper<T, nsCOMPtr<Pointee>>
{
typedef Pointee Type;
};
} // namespace detail
template<typename T>
struct RemoveSmartPointer
: detail::RemoveSmartPointerHelper<T, typename RemoveCV<T>::Type>
{};
namespace detail {
template<typename T, typename CVRemoved>
struct RemoveRawOrSmartPointerHelper
{
typedef T Type;
};
template<typename T, typename Pointee>
struct RemoveRawOrSmartPointerHelper<T, Pointee*>
{
typedef Pointee Type;
};
template<typename T, typename Pointee>
struct RemoveRawOrSmartPointerHelper<T, RefPtr<Pointee>>
{
typedef Pointee Type;
};
template<typename T, typename Pointee>
struct RemoveRawOrSmartPointerHelper<T, nsCOMPtr<Pointee>>
{
typedef Pointee Type;
};
} // namespace detail
template<typename T>
struct RemoveRawOrSmartPointer
: detail::RemoveRawOrSmartPointerHelper<T, typename RemoveCV<T>::Type>
{};
} // namespace mozilla
inline nsISupports*
ToSupports(mozilla::Runnable *p)
{
return static_cast<nsIRunnable*>(p);
}
template<typename Function>
already_AddRefed<mozilla::Runnable>
NS_NewRunnableFunction(const char* aName, Function&& aFunction)
{
// We store a non-reference in RunnableFunction, but still forward aFunction
// to move if possible.
return do_AddRef(
new mozilla::detail::RunnableFunctionImpl<Function>(
aName, mozilla::Forward<Function>(aFunction)));
}
namespace mozilla {
namespace detail {
template <RunnableKind Kind>
class TimerBehaviour
{
public:
nsITimer* GetTimer() { return nullptr; }
void CancelTimer() {}
protected:
~TimerBehaviour() {}
};
template <>
class TimerBehaviour<IdleWithTimer>
{
public:
nsITimer* GetTimer()
{
if (!mTimer) {
mTimer = NS_NewTimer();
}
return mTimer;
}
void CancelTimer()
{
if (mTimer) {
mTimer->Cancel();
}
}
protected:
~TimerBehaviour()
{
CancelTimer();
}
private:
nsCOMPtr<nsITimer> mTimer;
};
} // namespace detail
} // namespace mozilla
// An event that can be used to call a method on a class. The class type must
// support reference counting. This event supports Revoke for use
// with nsRevocableEventPtr.
template<class ClassType,
typename ReturnType = void,
bool Owning = true,
mozilla::RunnableKind Kind = mozilla::Standard>
class nsRunnableMethod
: public mozilla::Conditional<Kind == mozilla::Standard,
mozilla::Runnable,
typename mozilla::Conditional<
Kind == mozilla::Cancelable,
mozilla::CancelableRunnable,
mozilla::IdleRunnable>::Type>::Type,
protected mozilla::detail::TimerBehaviour<Kind>
{
using BaseType = typename mozilla::Conditional<Kind == mozilla::Standard,
mozilla::Runnable,
typename mozilla::Conditional<
Kind == mozilla::Cancelable,
mozilla::CancelableRunnable,
mozilla::IdleRunnable>::Type>::Type;
public:
nsRunnableMethod(const char* aName) : BaseType(aName) {}
virtual void Revoke() = 0;
// These ReturnTypeEnforcer classes set up a blacklist for return types that
// we know are not safe. The default ReturnTypeEnforcer compiles just fine but
// already_AddRefed will not.
template<typename OtherReturnType>
class ReturnTypeEnforcer
{
public:
typedef int ReturnTypeIsSafe;
};
template<class T>
class ReturnTypeEnforcer<already_AddRefed<T>>
{
// No ReturnTypeIsSafe makes this illegal!
};
// Make sure this return type is safe.
typedef typename ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafe check;
};
template<class ClassType, bool Owning>
struct nsRunnableMethodReceiver
{
RefPtr<ClassType> mObj;
explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
~nsRunnableMethodReceiver() { Revoke(); }
ClassType* Get() const { return mObj.get(); }
void Revoke() { mObj = nullptr; }
};
template<class ClassType>
struct nsRunnableMethodReceiver<ClassType, false>
{
ClassType* MOZ_NON_OWNING_REF mObj;
explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
ClassType* Get() const { return mObj; }
void Revoke() { mObj = nullptr; }
};
static inline constexpr bool
IsIdle(mozilla::RunnableKind aKind)
{
return aKind == mozilla::Idle || aKind == mozilla::IdleWithTimer;
}
template<typename PtrType, typename Method, bool Owning, mozilla::RunnableKind Kind>
struct nsRunnableMethodTraits;
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind, typename... As>
struct nsRunnableMethodTraits<PtrType, R(C::*)(As...), Owning, Kind>
{
typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind, typename... As>
struct nsRunnableMethodTraits<PtrType, R(C::*)(As...) const, Owning, Kind>
{
typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
#ifdef NS_HAVE_STDCALL
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind, typename... As>
struct nsRunnableMethodTraits<PtrType, R(__stdcall C::*)(As...), Owning, Kind>
{
typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind>
struct nsRunnableMethodTraits<PtrType, R(NS_STDCALL C::*)(), Owning, Kind>
{
typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind, typename... As>
struct nsRunnableMethodTraits<PtrType, R(__stdcall C::*)(As...) const, Owning, Kind>
{
typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
template<typename PtrType, class C, typename R, bool Owning, mozilla::RunnableKind Kind>
struct nsRunnableMethodTraits<PtrType, R(NS_STDCALL C::*)() const, Owning, Kind>
{
typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
static_assert(mozilla::IsBaseOf<C, class_type>::value,
"Stored class must inherit from method's class");
typedef R return_type;
typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
static const bool can_cancel = Kind == mozilla::Cancelable;
};
#endif
// IsParameterStorageClass<T>::value is true if T is a parameter-storage class
// that will be recognized by NS_New[NonOwning]RunnableMethodWithArg[s] to
// force a specific storage&passing strategy (instead of inferring one,
// see ParameterStorage).
// When creating a new storage class, add a specialization for it to be
// recognized.
template<typename T>
struct IsParameterStorageClass : public mozilla::FalseType {};
// StoreXPassByY structs used to inform nsRunnableMethodArguments how to
// store arguments, and how to pass them to the target method.
template<typename T>
struct StoreCopyPassByValue
{
typedef typename mozilla::Decay<T>::Type stored_type;
typedef stored_type passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByValue(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByValue<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreCopyPassByConstLRef
{
typedef typename mozilla::Decay<T>::Type stored_type;
typedef const stored_type& passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByConstLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByConstLRef<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreCopyPassByLRef
{
typedef typename mozilla::Decay<T>::Type stored_type;
typedef stored_type& passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByLRef(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByLRef<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreCopyPassByRRef
{
typedef typename mozilla::Decay<T>::Type stored_type;
typedef stored_type&& passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByRRef(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return mozilla::Move(m); }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByRRef<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreRefPassByLRef
{
typedef T& stored_type;
typedef T& passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreRefPassByLRef(A& a) : m(a) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreRefPassByLRef<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreConstRefPassByConstLRef
{
typedef const T& stored_type;
typedef const T& passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreConstRefPassByConstLRef(const A& a) : m(a) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreConstRefPassByConstLRef<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreRefPtrPassByPtr
{
typedef RefPtr<T> stored_type;
typedef T* passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreRefPtrPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return m.get(); }
};
template<typename S>
struct IsParameterStorageClass<StoreRefPtrPassByPtr<S>>
: public mozilla::TrueType {};
template<typename T>
struct StorePtrPassByPtr
{
typedef T* stored_type;
typedef T* passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StorePtrPassByPtr(A a) : m(a) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StorePtrPassByPtr<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreConstPtrPassByConstPtr
{
typedef const T* stored_type;
typedef const T* passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreConstPtrPassByConstPtr(A a) : m(a) {}
passed_type PassAsParameter() { return m; }
};
template<typename S>
struct IsParameterStorageClass<StoreConstPtrPassByConstPtr<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreCopyPassByConstPtr
{
typedef T stored_type;
typedef const T* passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByConstPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return &m; }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByConstPtr<S>>
: public mozilla::TrueType {};
template<typename T>
struct StoreCopyPassByPtr
{
typedef T stored_type;
typedef T* passed_type;
stored_type m;
template <typename A>
MOZ_IMPLICIT StoreCopyPassByPtr(A&& a) : m(mozilla::Forward<A>(a)) {}
passed_type PassAsParameter() { return &m; }
};
template<typename S>
struct IsParameterStorageClass<StoreCopyPassByPtr<S>>
: public mozilla::TrueType {};
namespace detail {
template<typename>
struct SFINAE1True : mozilla::TrueType
{};
template<class T>
static auto HasRefCountMethodsTest(int)
-> SFINAE1True<decltype(mozilla::DeclVal<T>().AddRef(),
mozilla::DeclVal<T>().Release())>;
template<class>
static auto HasRefCountMethodsTest(long) -> mozilla::FalseType;
template<class T>
struct HasRefCountMethods : decltype(HasRefCountMethodsTest<T>(0))
{};
template<typename TWithoutPointer>
struct NonnsISupportsPointerStorageClass
: mozilla::Conditional<mozilla::IsConst<TWithoutPointer>::value,
StoreConstPtrPassByConstPtr<
typename mozilla::RemoveConst<TWithoutPointer>::Type>,
StorePtrPassByPtr<TWithoutPointer>>
{};
template<typename TWithoutPointer>
struct PointerStorageClass
: mozilla::Conditional<HasRefCountMethods<TWithoutPointer>::value,
StoreRefPtrPassByPtr<TWithoutPointer>,
typename NonnsISupportsPointerStorageClass<
TWithoutPointer
>::Type>
{};
template<typename TWithoutRef>
struct LValueReferenceStorageClass
: mozilla::Conditional<mozilla::IsConst<TWithoutRef>::value,
StoreConstRefPassByConstLRef<
typename mozilla::RemoveConst<TWithoutRef>::Type>,
StoreRefPassByLRef<TWithoutRef>>
{};
template<typename T>
struct SmartPointerStorageClass
: mozilla::Conditional<mozilla::IsRefcountedSmartPointer<T>::value,
StoreRefPtrPassByPtr<
typename mozilla::RemoveSmartPointer<T>::Type>,
StoreCopyPassByConstLRef<T>>
{};
template<typename T>
struct NonLValueReferenceStorageClass
: mozilla::Conditional<mozilla::IsRvalueReference<T>::value,
StoreCopyPassByRRef<
typename mozilla::RemoveReference<T>::Type>,
typename SmartPointerStorageClass<T>::Type>
{};
template<typename T>
struct NonPointerStorageClass
: mozilla::Conditional<mozilla::IsLvalueReference<T>::value,
typename LValueReferenceStorageClass<
typename mozilla::RemoveReference<T>::Type
>::Type,
typename NonLValueReferenceStorageClass<T>::Type>
{};
template<typename T>
struct NonParameterStorageClass
: mozilla::Conditional<mozilla::IsPointer<T>::value,
typename PointerStorageClass<
typename mozilla::RemovePointer<T>::Type
>::Type,
typename NonPointerStorageClass<T>::Type>
{};
// Choose storage&passing strategy based on preferred storage type:
// - If IsParameterStorageClass<T>::value is true, use as-is.
// - RC* -> StoreRefPtrPassByPtr<RC> : Store RefPtr<RC>, pass RC*
// ^^ RC quacks like a ref-counted type (i.e., has AddRef and Release methods)
// - const T* -> StoreConstPtrPassByConstPtr<T> : Store const T*, pass const T*
// - T* -> StorePtrPassByPtr<T> : Store T*, pass T*.
// - const T& -> StoreConstRefPassByConstLRef<T>: Store const T&, pass const T&.
// - T& -> StoreRefPassByLRef<T> : Store T&, pass T&.
// - T&& -> StoreCopyPassByRRef<T> : Store T, pass Move(T).
// - RefPtr<T>, nsCOMPtr<T>
// -> StoreRefPtrPassByPtr<T> : Store RefPtr<T>, pass T*
// - Other T -> StoreCopyPassByConstLRef<T> : Store T, pass const T&.
// Other available explicit options:
// - StoreCopyPassByValue<T> : Store T, pass T.
// - StoreCopyPassByLRef<T> : Store T, pass T& (of copy!)
// - StoreCopyPassByConstPtr<T> : Store T, pass const T*
// - StoreCopyPassByPtr<T> : Store T, pass T* (of copy!)
// Or create your own class with PassAsParameter() method, optional
// clean-up in destructor, and with associated IsParameterStorageClass<>.
template<typename T>
struct ParameterStorage
: mozilla::Conditional<IsParameterStorageClass<T>::value,
T,
typename NonParameterStorageClass<T>::Type>
{};
template<class T>
static auto
HasSetDeadlineTest(int) -> SFINAE1True<decltype(
mozilla::DeclVal<T>().SetDeadline(mozilla::DeclVal<mozilla::TimeStamp>()))>;
template<class T>
static auto
HasSetDeadlineTest(long) -> mozilla::FalseType;
template<class T>
struct HasSetDeadline : decltype(HasSetDeadlineTest<T>(0))
{};
template <class T>
typename mozilla::EnableIf<::detail::HasSetDeadline<T>::value>::Type
SetDeadlineImpl(T* aObj, mozilla::TimeStamp aTimeStamp)
{
aObj->SetDeadline(aTimeStamp);
}
template <class T>
typename mozilla::EnableIf<!::detail::HasSetDeadline<T>::value>::Type
SetDeadlineImpl(T* aObj, mozilla::TimeStamp aTimeStamp)
{
}
} /* namespace detail */
namespace mozilla {
namespace detail {
// struct used to store arguments and later apply them to a method.
template <typename... Ts>
struct RunnableMethodArguments final
{
Tuple<typename ::detail::ParameterStorage<Ts>::Type...> mArguments;
template <typename... As>
explicit RunnableMethodArguments(As&&... aArguments)
: mArguments(Forward<As>(aArguments)...)
{}
template<typename C, typename M, typename... Args, size_t... Indices>
static auto
applyImpl(C* o, M m, Tuple<Args...>& args, std::index_sequence<Indices...>)
-> decltype(((*o).*m)(Get<Indices>(args).PassAsParameter()...))
{
return ((*o).*m)(Get<Indices>(args).PassAsParameter()...);
}
template<class C, typename M> auto apply(C* o, M m)
-> decltype(applyImpl(o, m, mArguments,
std::index_sequence_for<Ts...>{}))
{
return applyImpl(o, m, mArguments,
std::index_sequence_for<Ts...>{});
}
};
template<typename PtrType, typename Method, bool Owning, RunnableKind Kind, typename... Storages>
class RunnableMethodImpl final
: public ::nsRunnableMethodTraits<PtrType, Method, Owning, Kind>::base_type
{
typedef typename ::nsRunnableMethodTraits<PtrType, Method, Owning, Kind> Traits;
typedef typename Traits::class_type ClassType;
typedef typename Traits::base_type BaseType;
::nsRunnableMethodReceiver<ClassType, Owning> mReceiver;
Method mMethod;
RunnableMethodArguments<Storages...> mArgs;
using BaseType::GetTimer;
using BaseType::CancelTimer;
private:
virtual ~RunnableMethodImpl() { Revoke(); };
static void TimedOut(nsITimer* aTimer, void* aClosure)
{
static_assert(IsIdle(Kind), "Don't use me!");
RefPtr<IdleRunnable> r = static_cast<IdleRunnable*>(aClosure);
r->SetDeadline(TimeStamp());
r->Run();
r->Cancel();
}
public:
template<typename ForwardedPtrType, typename... Args>
explicit RunnableMethodImpl(const char* aName, ForwardedPtrType&& aObj,
Method aMethod, Args&&... aArgs)
: BaseType(aName)
, mReceiver(Forward<ForwardedPtrType>(aObj))
, mMethod(aMethod)
, mArgs(Forward<Args>(aArgs)...)
{
static_assert(sizeof...(Storages) == sizeof...(Args), "Storages and Args should have equal sizes");
}
NS_IMETHOD Run()
{
CancelTimer();
if (MOZ_LIKELY(mReceiver.Get())) {
mArgs.apply(mReceiver.Get(), mMethod);
}
return NS_OK;
}
nsresult Cancel()
{
static_assert(Kind >= Cancelable, "Don't use me!");
Revoke();
return NS_OK;
}
void Revoke()
{
CancelTimer();
mReceiver.Revoke();
}
void SetDeadline(TimeStamp aDeadline)
{
if (MOZ_LIKELY(mReceiver.Get())) {
::detail::SetDeadlineImpl(mReceiver.Get(), aDeadline);
}
}
void SetTimer(uint32_t aDelay, nsIEventTarget* aTarget)
{
MOZ_ASSERT(aTarget);
if (nsCOMPtr<nsITimer> timer = GetTimer()) {
timer->Cancel();
timer->SetTarget(aTarget);
timer->InitWithNamedFuncCallback(TimedOut,
this,
aDelay,
nsITimer::TYPE_ONE_SHOT,
"detail::RunnableMethodImpl::SetTimer");
}
}
};
// Type aliases for NewRunnableMethod.
template<typename PtrType, typename Method>
using OwningRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, true, Standard>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using OwningRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, true, Standard, Storages...>;
// Type aliases for NewCancelableRunnableMethod.
template<typename PtrType, typename Method>
using CancelableRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, true, Cancelable>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using CancelableRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, true, Cancelable, Storages...>;
// Type aliases for NewIdleRunnableMethod.
template<typename PtrType, typename Method>
using IdleRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, true, Idle>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using IdleRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, true, Idle, Storages...>;
// Type aliases for NewIdleRunnableMethodWithTimer.
template<typename PtrType, typename Method>
using IdleRunnableMethodWithTimer = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, true, IdleWithTimer>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using IdleRunnableMethodWithTimerImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, true, IdleWithTimer, Storages...>;
// Type aliases for NewNonOwningRunnableMethod.
template<typename PtrType, typename Method>
using NonOwningRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, false, Standard>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using NonOwningRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, false, Standard, Storages...>;
// Type aliases for NonOwningCancelableRunnableMethod
template<typename PtrType, typename Method>
using NonOwningCancelableRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, false, Cancelable>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using NonOwningCancelableRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, false, Cancelable, Storages...>;
// Type aliases for NonOwningIdleRunnableMethod
template<typename PtrType, typename Method>
using NonOwningIdleRunnableMethod = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, false, Idle>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using NonOwningIdleRunnableMethodImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, false, Idle, Storages...>;
// Type aliases for NewIdleRunnableMethodWithTimer.
template<typename PtrType, typename Method>
using NonOwningIdleRunnableMethodWithTimer = typename ::nsRunnableMethodTraits<
typename RemoveReference<PtrType>::Type, Method, false, IdleWithTimer>::base_type;
template<typename PtrType, typename Method, typename... Storages>
using NonOwningIdleRunnableMethodWithTimerImpl = RunnableMethodImpl<
typename RemoveReference<PtrType>::Type, Method, false, IdleWithTimer, Storages...>;
} // namespace detail
// NewRunnableMethod and friends
//
// Very often in Gecko, you'll find yourself in a situation where you want
// to invoke a method (with or without arguments) asynchronously. You
// could write a small helper class inheriting from nsRunnable to handle
// all these details, or you could let NewRunnableMethod take care of all
// those details for you.
//
// The simplest use of NewRunnableMethod looks like:
//
// nsCOMPtr<nsIRunnable> event =
// mozilla::NewRunnableMethod("description", myObject, &MyClass::HandleEvent);
// NS_DispatchToCurrentThread(event);
//
// Statically enforced constraints:
// - myObject must be of (or implicitly convertible to) type MyClass
// - MyClass must define AddRef and Release methods
//
// The "description" string should specify a human-readable name for the
// runnable; the provided string is used by various introspection tools
// in the browser.
//
// The created runnable will take a strong reference to `myObject`. For
// non-refcounted objects, or refcounted objects with unusual refcounting
// requirements, and if and only if you are 110% certain that `myObject`
// will live long enough, you can use NewNonOwningRunnableMethod instead,
// which will, as its name implies, take a non-owning reference. If you
// find yourself having to use this function, you should accompany your use
// with a proof comment describing why the runnable will not lead to
// use-after-frees.
//
// (If you find yourself writing contorted code to Release() an object
// asynchronously on a different thread, you should use the
// NS_ProxyRelease function.)
//
// Invoking a method with arguments takes a little more care. The
// natural extension of the above:
//
// nsCOMPtr<nsIRunnable> event =
// mozilla::NewRunnableMethod("description", myObject, &MyClass::HandleEvent,
// arg1, arg2, ...);
//
// can lead to security hazards (e.g. passing in raw pointers to refcounted
// objects and storing those raw pointers in the runnable). We therefore
// require you to specify the storage types used by the runnable, just as
// you would if you were writing out the class by hand:
//
// nsCOMPtr<nsIRunnable> event =
// mozilla::NewRunnableMethod<RefPtr<T>, nsTArray<U>>
// ("description", myObject, &MyClass::HandleEvent, arg1, arg2);
//
// Please note that you do not have to pass the same argument type as you
// specify in the template arguments. For example, if you want to transfer
// ownership to a runnable, you can write:
//
// RefPtr<T> ptr = ...;
// nsTArray<U> array = ...;
// nsCOMPtr<nsIRunnable> event =
// mozilla::NewRunnableMethod<RefPtr<T>, nsTArray<U>>
// ("description", myObject, &MyClass::DoSomething,
// Move(ptr), Move(array));
//
// and there will be no extra AddRef/Release traffic, or copying of the array.
//
// Each type that you specify as a template argument to NewRunnableMethod
// comes with its own style of storage in the runnable and its own style
// of argument passing to the invoked method. See the comment for
// ParameterStorage above for more details.
//
// If you need to customize the storage type and/or argument passing type,
// you can write your own class to use as a template argument to
// NewRunnableMethod. If you find yourself having to do that frequently,
// please file a bug in Core::XPCOM about adding the custom type to the
// core code in this file, and/or for custom rules for ParameterStorage
// to select that strategy.
//
// For places that require you to use cancelable runnables, such as
// workers, there's also NewCancelableRunnableMethod and its non-owning
// counterpart. The runnables returned by these methods additionally
// implement nsICancelableRunnable.
//
// Finally, all of the functions discussed above have additional overloads
// that do not take a `const char*` as their first parameter; you may see
// these in older code. The `const char*` overload is preferred and
// should be used in new code exclusively.
template<typename PtrType, typename Method>
already_AddRefed<detail::OwningRunnableMethod<PtrType, Method>>
NewRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod)
{
return do_AddRef(
new detail::OwningRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::CancelableRunnableMethod<PtrType, Method>>
NewCancelableRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod)
{
return do_AddRef(
new detail::CancelableRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::IdleRunnableMethod<PtrType, Method>>
NewIdleRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod)
{
return do_AddRef(
new detail::IdleRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::IdleRunnableMethodWithTimer<PtrType, Method>>
NewIdleRunnableMethodWithTimer(const char* aName,
PtrType&& aPtr,
Method aMethod)
{
return do_AddRef(
new detail::IdleRunnableMethodWithTimerImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::NonOwningRunnableMethod<PtrType, Method>>
NewNonOwningRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod)
{
return do_AddRef(
new detail::NonOwningRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::NonOwningCancelableRunnableMethod<PtrType, Method>>
NewNonOwningCancelableRunnableMethod(const char* aName, PtrType&& aPtr,
Method aMethod)
{
return do_AddRef(
new detail::NonOwningCancelableRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::NonOwningIdleRunnableMethod<PtrType, Method>>
NewNonOwningIdleRunnableMethod(const char* aName,
PtrType&& aPtr,
Method aMethod)
{
return do_AddRef(
new detail::NonOwningIdleRunnableMethodImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
template<typename PtrType, typename Method>
already_AddRefed<detail::NonOwningIdleRunnableMethodWithTimer<PtrType, Method>>
NewNonOwningIdleRunnableMethodWithTimer(const char* aName,
PtrType&& aPtr,
Method aMethod)
{
return do_AddRef(
new detail::NonOwningIdleRunnableMethodWithTimerImpl<PtrType, Method>(
aName, Forward<PtrType>(aPtr), aMethod));
}
// Similar to NewRunnableMethod. Call like so:
// nsCOMPtr<nsIRunnable> event =
// NewRunnableMethod<Types,...>(myObject, &MyClass::HandleEvent, myArg1,...);
// 'Types' are the stored type for each argument, see ParameterStorage for details.
template<typename... Storages, typename PtrType, typename Method, typename... Args>
already_AddRefed<detail::OwningRunnableMethod<PtrType, Method>>
NewRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod, Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::OwningRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
template<typename... Storages, typename PtrType, typename Method, typename... Args>
already_AddRefed<detail::NonOwningRunnableMethod<PtrType, Method>>
NewNonOwningRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::NonOwningRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
template<typename... Storages, typename PtrType, typename Method, typename... Args>
already_AddRefed<detail::CancelableRunnableMethod<PtrType, Method>>
NewCancelableRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::CancelableRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
template<typename... Storages, typename PtrType, typename Method, typename... Args>
already_AddRefed<detail::NonOwningCancelableRunnableMethod<PtrType, Method>>
NewNonOwningCancelableRunnableMethod(const char* aName, PtrType&& aPtr,
Method aMethod, Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::NonOwningCancelableRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
template<typename... Storages,
typename PtrType,
typename Method,
typename... Args>
already_AddRefed<detail::IdleRunnableMethod<PtrType, Method>>
NewIdleRunnableMethod(const char* aName,
PtrType&& aPtr,
Method aMethod,
Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::IdleRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
template<typename... Storages,
typename PtrType,
typename Method,
typename... Args>
already_AddRefed<detail::NonOwningIdleRunnableMethod<PtrType, Method>>
NewNonOwningIdleRunnableMethod(const char* aName,
PtrType&& aPtr,
Method aMethod,
Args&&... aArgs)
{
static_assert(sizeof...(Storages) == sizeof...(Args),
"<Storages...> size should be equal to number of arguments");
return do_AddRef(
new detail::NonOwningIdleRunnableMethodImpl<PtrType, Method, Storages...>(
aName, Forward<PtrType>(aPtr), aMethod, mozilla::Forward<Args>(aArgs)...));
}
} // namespace mozilla
#endif // XPCOM_GLUE_AVOID_NSPR
// This class is designed to be used when you have an event class E that has a
// pointer back to resource class R. If R goes away while E is still pending,
// then it is important to "revoke" E so that it does not try use R after R has
// been destroyed. nsRevocableEventPtr makes it easy for R to manage such
// situations:
//
// class R;
//
// class E : public mozilla::Runnable {
// public:
// void Revoke() {
// mResource = nullptr;
// }
// private:
// R *mResource;
// };
//
// class R {
// public:
// void EventHandled() {
// mEvent.Forget();
// }
// private:
// nsRevocableEventPtr<E> mEvent;
// };
//
// void R::PostEvent() {
// // Make sure any pending event is revoked.
// mEvent->Revoke();
//
// nsCOMPtr<nsIRunnable> event = new E();
// if (NS_SUCCEEDED(NS_DispatchToCurrentThread(event))) {
// // Keep pointer to event so we can revoke it.
// mEvent = event;
// }
// }
//
// NS_IMETHODIMP E::Run() {
// if (!mResource)
// return NS_OK;
// ...
// mResource->EventHandled();
// return NS_OK;
// }
//
template<class T>
class nsRevocableEventPtr
{
public:
nsRevocableEventPtr() : mEvent(nullptr) {}
~nsRevocableEventPtr() { Revoke(); }
const nsRevocableEventPtr& operator=(RefPtr<T>&& aEvent)
{
if (mEvent != aEvent) {
Revoke();
mEvent = Move(aEvent);
}
return *this;
}
void Revoke()
{
if (mEvent) {
mEvent->Revoke();
mEvent = nullptr;
}
}
void Forget() { mEvent = nullptr; }
bool IsPending() { return mEvent != nullptr; }
T* get() { return mEvent; }
private:
// Not implemented
nsRevocableEventPtr(const nsRevocableEventPtr&);
nsRevocableEventPtr& operator=(const nsRevocableEventPtr&);
RefPtr<T> mEvent;
};
template <class T>
inline already_AddRefed<T>
do_AddRef(nsRevocableEventPtr<T>& aObj)
{
return do_AddRef(aObj.get());
}
/**
* A simple helper to suffix thread pool name
* with incremental numbers.
*/
class nsThreadPoolNaming
{
public:
nsThreadPoolNaming() : mCounter(0) {}
/**
* Returns a thread name as "<aPoolName> #<n>" and increments the counter.
*/
nsCString GetNextThreadName(const nsACString& aPoolName);
template<size_t LEN>
nsCString GetNextThreadName(const char (&aPoolName)[LEN])
{
return GetNextThreadName(nsDependentCString(aPoolName, LEN - 1));
}
private:
mozilla::Atomic<uint32_t> mCounter;
nsThreadPoolNaming(const nsThreadPoolNaming&) = delete;
void operator=(const nsThreadPoolNaming&) = delete;
};
/**
* Thread priority in most operating systems affect scheduling, not IO. This
* helper is used to set the current thread to low IO priority for the lifetime
* of the created object. You can only use this low priority IO setting within
* the context of the current thread.
*/
class MOZ_STACK_CLASS nsAutoLowPriorityIO
{
public:
nsAutoLowPriorityIO();
~nsAutoLowPriorityIO();
private:
bool lowIOPrioritySet;
#if defined(XP_MACOSX)
int oldPriority;
#endif
};
void
NS_SetMainThread();
// Used only on cooperatively scheduled "main" threads. Causes the thread to be
// considered a main thread and also causes GetCurrentVirtualThread to return
// aVirtualThread.
void
NS_SetMainThread(PRThread* aVirtualThread);
// Used only on cooperatively scheduled "main" threads. Causes the thread to no
// longer be considered a main thread. Also causes GetCurrentVirtualThread() to
// return a unique value.
void
NS_UnsetMainThread();
/**
* Return the expiration time of the next timer to run on the current
* thread. If that expiration time is greater than aDefault, then
* return aDefault. aSearchBound specifies a maximum number of timers
* to examine to find a timer on the current thread. If no timer that
* will run on the current thread is found after examining
* aSearchBound timers, return the highest seen expiration time as a
* best effort guess.
*
* Timers with either the type nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY or
* nsITIMER::TYPE_REPEATING_SLACK_LOW_PRIORITY will be skipped when
* searching for the next expiration time. This enables timers to
* have lower priority than callbacks dispatched from
* nsIThread::IdleDispatch.
*/
extern mozilla::TimeStamp
NS_GetTimerDeadlineHintOnCurrentThread(mozilla::TimeStamp aDefault, uint32_t aSearchBound);
namespace mozilla {
/**
* Cooperative thread scheduling is governed by two rules:
* - Only one thread in the pool of cooperatively scheduled threads runs at a
* time.
* - Thread switching happens at well-understood safe points.
*
* In some cases we may want to treat all the threads in a cooperative pool as a
* single thread, while other parts of the code may want to view them as separate
* threads. GetCurrentVirtualThread() will return the same value for all
* threads in a cooperative thread pool. GetCurrentPhysicalThread will return a
* different value for each thread in the pool.
*
* Thread safety assertions are a concrete example where GetCurrentVirtualThread
* should be used. An object may want to assert that it only can be used on the
* thread that created it. Such assertions would normally prevent the object
* from being used on different cooperative threads. However, the object might
* really only care that it's used atomically. Cooperative scheduling guarantees
* that it will be (assuming we don't yield in the middle of modifying the
* object). So we can weaken the assertion to compare the virtual thread the
* object was created on to the virtual thread on which it's being used. This
* assertion allows the object to be used across threads in a cooperative thread
* pool while preventing accesses across preemptively scheduled threads (which
* would be unsafe).
*/
// Returns the PRThread on which this code is running.
PRThread*
GetCurrentPhysicalThread();
// Returns a "virtual" PRThread that should only be used for comparison with
// other calls to GetCurrentVirtualThread. Two threads in the same cooperative
// thread pool will return the same virtual thread. Threads that are not
// cooperatively scheduled will have their own unique virtual PRThread (which
// will be equal to their physical PRThread).
//
// The return value of GetCurrentVirtualThread() is guaranteed not to change
// throughout the lifetime of a thread.
//
// Note that the original main thread (the first one created in the process) is
// considered as part of the pool of cooperative threads, so the return value of
// GetCurrentVirtualThread() for this thread (throughout its lifetime, even
// during shutdown) is the same as the return value from any other thread in the
// cooperative pool.
PRThread*
GetCurrentVirtualThread();
// These functions return event targets that can be used to dispatch to the
// current or main thread. They can also be used to test if you're on those
// threads (via IsOnCurrentThread). These functions should be used in preference
// to the nsIThread-based NS_Get{Current,Main}Thread functions since they will
// return more useful answers in the case of threads sharing an event loop.
nsIEventTarget*
GetCurrentThreadEventTarget();
nsIEventTarget*
GetMainThreadEventTarget();
// These variants of the above functions assert that the given thread has a
// serial event target (i.e., that it's not part of a thread pool) and returns
// that.
nsISerialEventTarget*
GetCurrentThreadSerialEventTarget();
nsISerialEventTarget*
GetMainThreadSerialEventTarget();
} // namespace mozilla
#endif // nsThreadUtils_h__