466 lines
18 KiB
C++
466 lines
18 KiB
C++
/*
|
|
==============================================================================
|
|
|
|
This file is part of the JUCE library.
|
|
Copyright (c) 2017 - ROLI Ltd.
|
|
|
|
JUCE is an open source library subject to commercial or open-source
|
|
licensing.
|
|
|
|
The code included in this file is provided under the terms of the ISC license
|
|
http://www.isc.org/downloads/software-support-policy/isc-license. Permission
|
|
To use, copy, modify, and/or distribute this software for any purpose with or
|
|
without fee is hereby granted provided that the above copyright notice and
|
|
this permission notice appear in all copies.
|
|
|
|
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
|
|
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
|
|
DISCLAIMED.
|
|
|
|
==============================================================================
|
|
*/
|
|
|
|
namespace juce
|
|
{
|
|
|
|
class MessageManagerLock;
|
|
class ThreadPoolJob;
|
|
class ActionListener;
|
|
class ActionBroadcaster;
|
|
|
|
//==============================================================================
|
|
#if JUCE_MODULE_AVAILABLE_juce_opengl
|
|
class OpenGLContext;
|
|
#endif
|
|
|
|
//==============================================================================
|
|
/** See MessageManager::callFunctionOnMessageThread() for use of this function type. */
|
|
typedef void* (MessageCallbackFunction) (void* userData);
|
|
|
|
|
|
//==============================================================================
|
|
/**
|
|
This class is in charge of the application's event-dispatch loop.
|
|
|
|
@see Message, CallbackMessage, MessageManagerLock, JUCEApplication, JUCEApplicationBase
|
|
|
|
@tags{Events}
|
|
*/
|
|
class JUCE_API MessageManager final
|
|
{
|
|
public:
|
|
//==============================================================================
|
|
/** Returns the global instance of the MessageManager. */
|
|
static MessageManager* getInstance();
|
|
|
|
/** Returns the global instance of the MessageManager, or nullptr if it doesn't exist. */
|
|
static MessageManager* getInstanceWithoutCreating() noexcept;
|
|
|
|
/** Deletes the global MessageManager instance.
|
|
Does nothing if no instance had been created.
|
|
*/
|
|
static void deleteInstance();
|
|
|
|
//==============================================================================
|
|
/** 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 stopDispatchLoop
|
|
*/
|
|
void runDispatchLoop();
|
|
|
|
/** 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 runDispatchLoop
|
|
*/
|
|
void stopDispatchLoop();
|
|
|
|
/** Returns true if the stopDispatchLoop() method has been called.
|
|
*/
|
|
bool hasStopMessageBeenSent() const noexcept { return quitMessagePosted.get() != 0; }
|
|
|
|
#if JUCE_MODAL_LOOPS_PERMITTED || DOXYGEN
|
|
/** 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.
|
|
*/
|
|
bool runDispatchLoopUntil (int millisecondsToRunFor);
|
|
#endif
|
|
|
|
//==============================================================================
|
|
/** Asynchronously invokes a function or C++11 lambda on the message thread. */
|
|
template <typename FunctionType>
|
|
static void callAsync (FunctionType functionToCall)
|
|
{
|
|
new AsyncCallInvoker<FunctionType> (functionToCall);
|
|
}
|
|
|
|
/** 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.
|
|
|
|
@param callback the function to call - its signature must be @code
|
|
void* myCallbackFunction (void*) @endcode
|
|
@param userData a user-defined pointer that will be passed to the function that gets called
|
|
@returns the value that the callback function returns.
|
|
@see MessageManagerLock
|
|
*/
|
|
void* callFunctionOnMessageThread (MessageCallbackFunction* callback, void* userData);
|
|
|
|
/** Returns true if the caller-thread is the message thread. */
|
|
bool isThisTheMessageThread() const noexcept;
|
|
|
|
/** Called to tell the manager that the current thread is the one that's running the dispatch loop.
|
|
|
|
(Best to ignore this method unless you really know what you're doing..)
|
|
@see getCurrentMessageThread
|
|
*/
|
|
void setCurrentThreadAsMessageThread();
|
|
|
|
/** Returns the ID of the current message thread, as set by setCurrentThreadAsMessageThread().
|
|
|
|
(Best to ignore this method unless you really know what you're doing..)
|
|
@see setCurrentThreadAsMessageThread
|
|
*/
|
|
Thread::ThreadID getCurrentMessageThread() const noexcept { return messageThreadId; }
|
|
|
|
/** Returns true if the caller thread has currently got the message manager locked.
|
|
|
|
see the MessageManagerLock class for more info about this.
|
|
|
|
This will be true if the caller is the message thread, because that automatically
|
|
gains a lock while a message is being dispatched.
|
|
*/
|
|
bool currentThreadHasLockedMessageManager() const noexcept;
|
|
|
|
//==============================================================================
|
|
/** Sends a message to all other JUCE applications that are running.
|
|
|
|
@param messageText the string that will be passed to the actionListenerCallback()
|
|
method of the broadcast listeners in the other app.
|
|
@see registerBroadcastListener, ActionListener
|
|
*/
|
|
static void broadcastMessage (const String& messageText);
|
|
|
|
/** Registers a listener to get told about broadcast messages.
|
|
|
|
The actionListenerCallback() callback's string parameter
|
|
is the message passed into broadcastMessage().
|
|
|
|
@see broadcastMessage
|
|
*/
|
|
void registerBroadcastListener (ActionListener* listener);
|
|
|
|
/** Deregisters a broadcast listener. */
|
|
void deregisterBroadcastListener (ActionListener* listener);
|
|
|
|
//==============================================================================
|
|
/** Internal class used as the base class for all message objects.
|
|
You shouldn't need to use this directly - see the CallbackMessage or Message
|
|
classes instead.
|
|
*/
|
|
class JUCE_API MessageBase : public ReferenceCountedObject
|
|
{
|
|
public:
|
|
MessageBase() noexcept {}
|
|
virtual ~MessageBase() {}
|
|
|
|
virtual void messageCallback() = 0;
|
|
bool post();
|
|
|
|
using Ptr = ReferenceCountedObjectPtr<MessageBase>;
|
|
|
|
JUCE_DECLARE_NON_COPYABLE (MessageBase)
|
|
};
|
|
|
|
//==============================================================================
|
|
/** A lock you can use to lock the message manager. You can use this class with
|
|
the RAII-based ScopedLock classes.
|
|
*/
|
|
class Lock
|
|
{
|
|
public:
|
|
/**
|
|
Creates a new critical section to exclusively access methods which can
|
|
only be called when the message manager is locked.
|
|
|
|
Unlike CrititcalSection, multiple instances of this lock class provide
|
|
exclusive access to a single resource - the MessageManager.
|
|
*/
|
|
Lock();
|
|
|
|
/** Destructor. */
|
|
~Lock();
|
|
|
|
/** 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 accquired by this thread. Calling abort while
|
|
a thread is waiting for enter to finish, will have no effect.
|
|
|
|
@see exit, abort
|
|
*/
|
|
void enter() const noexcept;
|
|
|
|
/** Attempts to lock the meesage 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 accquired.
|
|
@see enter, abort, ScopedTryLock
|
|
*/
|
|
bool tryEnter() const noexcept;
|
|
|
|
/** Releases the message manager lock.
|
|
@see enter, ScopedLock
|
|
*/
|
|
void exit() 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 effetc on a thread waiting for a lock in enter.
|
|
@see tryEnter
|
|
*/
|
|
void abort() const noexcept;
|
|
|
|
//==============================================================================
|
|
/** Provides the type of scoped lock to use with a CriticalSection. */
|
|
typedef GenericScopedLock<Lock> ScopedLockType;
|
|
|
|
/** Provides the type of scoped unlocker to use with a CriticalSection. */
|
|
typedef GenericScopedUnlock<Lock> ScopedUnlockType;
|
|
|
|
/** Provides the type of scoped try-locker to use with a CriticalSection. */
|
|
typedef GenericScopedTryLock<Lock> ScopedTryLockType;
|
|
|
|
private:
|
|
struct BlockingMessage;
|
|
friend class ReferenceCountedObjectPtr<BlockingMessage>;
|
|
|
|
bool tryAcquire (bool) const noexcept;
|
|
void messageCallback() const;
|
|
|
|
//==============================================================================
|
|
mutable ReferenceCountedObjectPtr<BlockingMessage> blockingMessage;
|
|
WaitableEvent lockedEvent;
|
|
mutable Atomic<int> abortWait, lockGained;
|
|
};
|
|
|
|
//==============================================================================
|
|
#ifndef DOXYGEN
|
|
// Internal methods - do not use!
|
|
void deliverBroadcastMessage (const String&);
|
|
~MessageManager() noexcept;
|
|
#endif
|
|
|
|
private:
|
|
//==============================================================================
|
|
MessageManager() noexcept;
|
|
|
|
static MessageManager* instance;
|
|
|
|
friend class MessageBase;
|
|
class QuitMessage;
|
|
friend class QuitMessage;
|
|
friend class MessageManagerLock;
|
|
|
|
std::unique_ptr<ActionBroadcaster> broadcaster;
|
|
Atomic<int> quitMessagePosted { 0 }, quitMessageReceived { 0 };
|
|
Thread::ThreadID messageThreadId;
|
|
Atomic<Thread::ThreadID> threadWithLock;
|
|
|
|
static bool postMessageToSystemQueue (MessageBase*);
|
|
static void* exitModalLoopCallback (void*);
|
|
static void doPlatformSpecificInitialisation();
|
|
static void doPlatformSpecificShutdown();
|
|
static bool dispatchNextMessageOnSystemQueue (bool returnIfNoPendingMessages);
|
|
|
|
template <typename FunctionType>
|
|
struct AsyncCallInvoker : public MessageBase
|
|
{
|
|
AsyncCallInvoker (FunctionType f) : callback (f) { post(); }
|
|
void messageCallback() override { callback(); }
|
|
FunctionType callback;
|
|
|
|
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AsyncCallInvoker)
|
|
};
|
|
|
|
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MessageManager)
|
|
};
|
|
|
|
|
|
//==============================================================================
|
|
/** Used to make sure that the calling thread has exclusive access to the message loop.
|
|
|
|
Because it's not thread-safe to call any of the Component or other UI classes
|
|
from threads other than the message thread, one of these objects can be used to
|
|
lock the message loop and allow this to be done. The message thread will be
|
|
suspended for the lifetime of the MessageManagerLock object, so create one on
|
|
the stack like this: @code
|
|
void MyThread::run()
|
|
{
|
|
someData = 1234;
|
|
|
|
const MessageManagerLock mmLock;
|
|
// the event loop will now be locked so it's safe to make a few calls..
|
|
|
|
myComponent->setBounds (newBounds);
|
|
myComponent->repaint();
|
|
|
|
// ..the event loop will now be unlocked as the MessageManagerLock goes out of scope
|
|
}
|
|
@endcode
|
|
|
|
Obviously be careful not to create one of these and leave it lying around, or
|
|
your app will grind to a halt!
|
|
|
|
MessageManagerLocks are re-entrant, so can be safely nested if the current thread
|
|
already has the lock.
|
|
|
|
Another caveat is that using this in conjunction with other CriticalSections
|
|
can create lots of interesting ways of producing a deadlock! In particular, if
|
|
your message thread calls stopThread() for a thread that uses these locks,
|
|
you'll get an (occasional) deadlock..
|
|
|
|
@see MessageManager, MessageManager::currentThreadHasLockedMessageManager
|
|
|
|
@tags{Events}
|
|
*/
|
|
class JUCE_API MessageManagerLock : private Thread::Listener
|
|
{
|
|
public:
|
|
//==============================================================================
|
|
/** Tries to acquire a lock on the message manager.
|
|
|
|
The constructor attempts to gain a lock on the message loop, and the lock will be
|
|
kept for the lifetime of this object.
|
|
|
|
Optionally, you can pass a thread object here, and while waiting to obtain the lock,
|
|
this method will keep checking whether the thread has been given the
|
|
Thread::signalThreadShouldExit() signal. If this happens, then it will return
|
|
without gaining the lock. If you pass a thread, you must check whether the lock was
|
|
successful by calling lockWasGained(). If this is false, your thread is being told to
|
|
die, so you should take evasive action.
|
|
|
|
If you pass nullptr for the thread object, it will wait indefinitely for the lock - be
|
|
careful when doing this, because it's very easy to deadlock if your message thread
|
|
attempts to call stopThread() on a thread just as that thread attempts to get the
|
|
message lock.
|
|
|
|
If the calling thread already has the lock, nothing will be done, so it's safe and
|
|
quick to use these locks recursively.
|
|
|
|
E.g.
|
|
@code
|
|
void run()
|
|
{
|
|
...
|
|
|
|
while (! threadShouldExit())
|
|
{
|
|
MessageManagerLock mml (Thread::getCurrentThread());
|
|
|
|
if (! mml.lockWasGained())
|
|
return; // another thread is trying to kill us!
|
|
|
|
..do some locked stuff here..
|
|
}
|
|
|
|
..and now the MM is now unlocked..
|
|
}
|
|
@endcode
|
|
|
|
*/
|
|
MessageManagerLock (Thread* threadToCheckForExitSignal = nullptr);
|
|
|
|
//==============================================================================
|
|
/** This has the same behaviour as the other constructor, but takes a ThreadPoolJob
|
|
instead of a thread.
|
|
|
|
See the MessageManagerLock (Thread*) constructor for details on how this works.
|
|
*/
|
|
MessageManagerLock (ThreadPoolJob* jobToCheckForExitSignal);
|
|
|
|
//==============================================================================
|
|
/** Releases the current thread's lock on the message manager.
|
|
|
|
Make sure this object is created and deleted by the same thread,
|
|
otherwise there are no guarantees what will happen!
|
|
*/
|
|
~MessageManagerLock() noexcept;
|
|
|
|
//==============================================================================
|
|
/** Returns true if the lock was successfully acquired.
|
|
(See the constructor that takes a Thread for more info).
|
|
*/
|
|
bool lockWasGained() const noexcept { return locked; }
|
|
|
|
private:
|
|
//==============================================================================
|
|
MessageManager::Lock mmLock;
|
|
bool locked;
|
|
|
|
//==============================================================================
|
|
bool attemptLock (Thread*, ThreadPoolJob*);
|
|
void exitSignalSent() override;
|
|
|
|
JUCE_DECLARE_NON_COPYABLE (MessageManagerLock)
|
|
};
|
|
|
|
} // namespace juce
|