juce::MessageManager::Lock Class Reference

A lock you can use to lock the message manager. More...

#include <juce_MessageManager.h>

Collaboration diagram for juce::MessageManager::Lock:

Public Types
using	ScopedLockType = GenericScopedLock< Lock >
	Provides the type of scoped lock to use with a CriticalSection. More...
using	ScopedTryLockType = GenericScopedTryLock< Lock >
	Provides the type of scoped try-locker to use with a CriticalSection. More...
using	ScopedUnlockType = GenericScopedUnlock< Lock >
	Provides the type of scoped unlocker to use with a CriticalSection. More...

Public Member Functions
	Lock ()
	Creates a new critical section to exclusively access methods which can only be called when the message manager is locked. More...
	~Lock ()
	Destructor. More...
void	abort () const noexcept
	Unblocks a thread which is waiting in tryEnter Call this method if you want to unblock a thread which is waiting for the MessageManager lock in tryEnter. More...
void	enter () const noexcept
	Acquires the message manager lock. More...
void	exit () const noexcept
	Releases the message manager lock. More...
bool	tryEnter () const noexcept
	Attempts to lock the message manager and exits if abort is called. More...

Private Member Functions
void	messageCallback () const
bool	tryAcquire (bool) const noexcept

Private Attributes
Atomic< int >	abortWait
ReferenceCountedObjectPtr< BlockingMessage >	blockingMessage
WaitableEvent	lockedEvent
Atomic< int >	lockGained

Friends
class	ReferenceCountedObjectPtr< BlockingMessage >

Detailed Description

A lock you can use to lock the message manager.

You can use this class with the RAII-based ScopedLock classes.

Member Typedef Documentation

ScopedLockType

using juce::MessageManager::Lock::ScopedLockType = GenericScopedLock<Lock>

Provides the type of scoped lock to use with a CriticalSection.

ScopedTryLockType

using juce::MessageManager::Lock::ScopedTryLockType = GenericScopedTryLock<Lock>

Provides the type of scoped try-locker to use with a CriticalSection.

ScopedUnlockType

using juce::MessageManager::Lock::ScopedUnlockType = GenericScopedUnlock<Lock>

Provides the type of scoped unlocker to use with a CriticalSection.

Constructor & Destructor Documentation

Lock()

juce::MessageManager::Lock::Lock

(

)

Creates a new critical section to exclusively access methods which can only be called when the message manager is locked.

Unlike CriticalSection, multiple instances of this lock class provide exclusive access to a single resource - the MessageManager.

~Lock()

juce::MessageManager::Lock::~Lock

(

)

Destructor.

Member Function Documentation

abort()

void juce::MessageManager::Lock::abort ( ) const

noexcept

Unblocks a thread which is waiting in tryEnter Call this method if you want to unblock a thread which is waiting for the MessageManager lock in tryEnter.

This method does not have any effect on a thread waiting for a lock in enter.

See also

tryEnter

enter()

void juce::MessageManager::Lock::enter ( ) const

noexcept

Acquires the message manager lock.

If the caller thread already has exclusive access to the MessageManager, this method will return immediately. If another thread is currently using the MessageManager, this will wait until that thread releases the lock to the MessageManager.

This call will only exit if the lock was acquired by this thread. Calling abort while a thread is waiting for enter to finish, will have no effect.

See also

exit, abort

exit()

void juce::MessageManager::Lock::exit ( ) const

noexcept

Releases the message manager lock.

See also

enter, ScopedLock

messageCallback()

void juce::MessageManager::Lock::messageCallback ( ) const

private

tryAcquire()

bool juce::MessageManager::Lock::tryAcquire ( bool  ) const

privatenoexcept

tryEnter()

bool juce::MessageManager::Lock::tryEnter ( ) const

noexcept

Attempts to lock the message manager and exits if abort is called.

This method behaves identically to enter, except that it will abort waiting for the lock if the abort method is called.

Unlike other JUCE critical sections, this method will block waiting for the lock.

To ensure predictable behaviour, you should re-check your abort condition if tryEnter returns false.

This method can be used if you want to do some work while waiting for the MessageManagerLock:

void doWorkWhileWaitingForMessageManagerLock() { MessageManager::Lock::ScopedTryLockType mmLock (messageManagerLock);

while (! mmLock.isLocked()) { while (workQueue.size() > 0) { auto work = workQueue.pop(); doSomeWork (work); }

this will block until we either have the lock or there is work mmLock.retryLock(); }

we have the mmlock do some message manager stuff like resizing and painting components }

called from another thread void addWorkToDo (Work work) { queue.push (work); messageManagerLock.abort(); }

Returns

false if waiting for a lock was aborted, true if the lock was acquired.

See also

enter, abort, ScopedTryLock

Friends And Related Function Documentation

ReferenceCountedObjectPtr< BlockingMessage >

friend class ReferenceCountedObjectPtr< BlockingMessage >

friend

Member Data Documentation

abortWait

Atomic<int> juce::MessageManager::Lock::abortWait

mutableprivate

blockingMessage

ReferenceCountedObjectPtr<BlockingMessage> juce::MessageManager::Lock::blockingMessage

mutableprivate

lockedEvent

WaitableEvent juce::MessageManager::Lock::lockedEvent

private

lockGained

Atomic<int> juce::MessageManager::Lock::lockGained

private

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The documentation for this class was generated from the following file:

• juce_MessageManager.h