This class is in charge of the application's event-dispatch loop. More...

Classes
class	Lock
	A lock you can use to lock the message manager. More...

class	MessageBase
	Internal class used as the base class for all message objects. More...

Public Member Functions
void	runDispatchLoop ()
	Runs the event dispatch loop until a stop message is posted.

void	stopDispatchLoop ()
	Sends a signal that the dispatch loop should terminate.

bool	hasStopMessageBeenSent () const noexcept
	Returns true if the stopDispatchLoop() method has been called.

bool	runDispatchLoopUntil (int millisecondsToRunFor)
	Synchronously dispatches messages until a given time has elapsed.

void *	callFunctionOnMessageThread (MessageCallbackFunction callback, void userData)
	Calls a function using the message-thread.

bool	isThisTheMessageThread () const noexcept
	Returns true if the caller-thread is the message thread.

void	setCurrentThreadAsMessageThread ()
	Called to tell the manager that the current thread is the one that's running the dispatch loop.

Thread::ThreadID	getCurrentMessageThread () const noexcept
	Returns the ID of the current message thread, as set by setCurrentThreadAsMessageThread().

bool	currentThreadHasLockedMessageManager () const noexcept
	Returns true if the caller thread has currently got the message manager locked.

void	registerBroadcastListener (ActionListener *listener)
	Registers a listener to get told about broadcast messages.

void	deregisterBroadcastListener (ActionListener *listener)
	Deregisters a broadcast listener.

Static Public Member Functions
static MessageManager *	getInstance ()
	Returns the global instance of the MessageManager.

static MessageManager *	getInstanceWithoutCreating () noexcept
	Returns the global instance of the MessageManager, or nullptr if it doesn't exist.

static void	deleteInstance ()
	Deletes the global MessageManager instance.

template<typename Function>
static bool	callAsync (Function &&function)
	Asynchronously invokes a function or C++11 lambda on the message thread.

template<typename Function>
static auto	callSync (Function &&function) -> CallSyncResult< decltype(function())>
	Similar to callFunctionOnMessageThread(), calls a function on the message thread, blocking the current thread until a result is available.

static bool	existsAndIsLockedByCurrentThread () noexcept
	Returns true if there's an instance of the MessageManager, and if the current thread has the lock on it.

static bool	existsAndIsCurrentThread () noexcept
	Returns true if there's an instance of the MessageManager, and if the current thread is running it.

static void	broadcastMessage (const String &messageText)
	Sends a message to all other JUCE applications that are running.

Detailed Description

This class is in charge of the application's event-dispatch loop.

See also: Message, CallbackMessage, MessageManagerLock, JUCEApplication, JUCEApplicationBase

Member Function Documentation

◆ getInstance()

static MessageManager * MessageManager::getInstance ( )

static

Returns the global instance of the MessageManager.

Referenced by callSync().

◆ getInstanceWithoutCreating()

static MessageManager * MessageManager::getInstanceWithoutCreating ( )

staticnoexcept

Returns the global instance of the MessageManager, or nullptr if it doesn't exist.

◆ deleteInstance()

static void MessageManager::deleteInstance ( )

static

Deletes the global MessageManager instance.

Does nothing if no instance had been created.

References deleteInstance().

Referenced by deleteInstance().

◆ runDispatchLoop()

void MessageManager::runDispatchLoop ( )

Runs the event dispatch loop until a stop message is posted.

This method is only intended to be run by the application's startup routine, as it blocks, and will only return after the stopDispatchLoop() method has been used.

See also: stopDispatchLoop

References runDispatchLoop().

Referenced by runDispatchLoop().

◆ stopDispatchLoop()

void MessageManager::stopDispatchLoop ( )

Sends a signal that the dispatch loop should terminate.

After this is called, the runDispatchLoop() or runDispatchLoopUntil() methods will be interrupted and will return.

See also: runDispatchLoop

References stopDispatchLoop().

Referenced by stopDispatchLoop().

◆ hasStopMessageBeenSent()

bool MessageManager::hasStopMessageBeenSent ( ) const

noexcept

Returns true if the stopDispatchLoop() method has been called.

References hasStopMessageBeenSent().

Referenced by hasStopMessageBeenSent().

◆ runDispatchLoopUntil()

bool MessageManager::runDispatchLoopUntil ( int millisecondsToRunFor )

Synchronously dispatches messages until a given time has elapsed.

Returns false if a quit message has been posted by a call to stopDispatchLoop(), otherwise returns true.

◆ callAsync()

template<typename Function>

static bool MessageManager::callAsync ( Function && function )

static

Asynchronously invokes a function or C++11 lambda on the message thread.

Parameters

function the function to call, which should have no arguments

Returns: true if the message was successfully posted to the message queue, or false otherwise.

Referenced by callSync().

◆ callFunctionOnMessageThread()

void * MessageManager::callFunctionOnMessageThread	(	MessageCallbackFunction *	callback,
		void *	userData )

Calls a function using the message-thread.

This can be used by any thread to cause this function to be called-back by the message thread. If it's the message-thread that's calling this method, then the function will just be called; if another thread is calling, a message will be posted to the queue, and this method will block until that message is delivered, the function is called, and the result is returned.

Be careful not to cause any deadlocks with this! It's easy to do - e.g. if the caller thread has a critical section locked, which an unrelated message callback then tries to lock before the message thread gets round to processing this callback.

Parameters

callback	the function to call - its signature must be void* myCallbackFunction (void*)
userData	a user-defined pointer that will be passed to the function that gets called

Returns: the value that the callback function returns.

See also: MessageManagerLock

◆ callSync()

template<typename Function>

static auto MessageManager::callSync ( Function && function ) -> CallSyncResult<decltype (function())>

static

Similar to callFunctionOnMessageThread(), calls a function on the message thread, blocking the current thread until a result is available.

Be careful not to cause any deadlocks with this! It's easy to do - e.g. if the caller thread has a critical section locked, which an unrelated message callback then tries to lock before the message thread gets round to processing this callback.

Parameters

function the function to call, which should have no parameters

Returns: if function() returns void, then callSync returns a boolean where 'true' indicates that the function was called successfully, and 'false' indicates that the message could not be posted. if function() returns any other type 'T', then callSync returns std::optional<T>, where the optional value will be valid if the function was called successfully, or nullopt otherwise.

References callAsync(), getInstance(), isThisTheMessageThread(), and jassertfalse.