OpenShot Library | OpenShotAudio 0.2.2
juce_MessageManager.cpp
1/*
2 ==============================================================================
3
4 This file is part of the JUCE library.
5 Copyright (c) 2017 - ROLI Ltd.
6
7 JUCE is an open source library subject to commercial or open-source
8 licensing.
9
10 The code included in this file is provided under the terms of the ISC license
11 http://www.isc.org/downloads/software-support-policy/isc-license. Permission
12 To use, copy, modify, and/or distribute this software for any purpose with or
13 without fee is hereby granted provided that the above copyright notice and
14 this permission notice appear in all copies.
15
16 JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
17 EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
18 DISCLAIMED.
19
20 ==============================================================================
21*/
22
23namespace juce
24{
25
26MessageManager::MessageManager() noexcept
27 : messageThreadId (Thread::getCurrentThreadId())
28{
30 Thread::setCurrentThreadName ("JUCE Message Thread");
31}
32
33MessageManager::~MessageManager() noexcept
34{
35 broadcaster.reset();
36
37 doPlatformSpecificShutdown();
38
39 jassert (instance == this);
40 instance = nullptr; // do this last in case this instance is still needed by doPlatformSpecificShutdown()
41}
42
43MessageManager* MessageManager::instance = nullptr;
44
46{
47 if (instance == nullptr)
48 {
49 instance = new MessageManager();
50 doPlatformSpecificInitialisation();
51 }
52
53 return instance;
54}
55
57{
58 return instance;
59}
60
62{
63 deleteAndZero (instance);
64}
65
66//==============================================================================
67bool MessageManager::MessageBase::post()
68{
69 auto* mm = MessageManager::instance;
70
71 if (mm == nullptr || mm->quitMessagePosted.get() != 0 || ! postMessageToSystemQueue (this))
72 {
73 Ptr deleter (this); // (this will delete messages that were just created with a 0 ref count)
74 return false;
75 }
76
77 return true;
78}
79
80//==============================================================================
81#if JUCE_MODAL_LOOPS_PERMITTED && ! (JUCE_MAC || JUCE_IOS)
82bool MessageManager::runDispatchLoopUntil (int millisecondsToRunFor)
83{
84 jassert (isThisTheMessageThread()); // must only be called by the message thread
85
86 auto endTime = Time::currentTimeMillis() + millisecondsToRunFor;
87
88 while (quitMessageReceived.get() == 0)
89 {
90 JUCE_TRY
91 {
92 if (! dispatchNextMessageOnSystemQueue (millisecondsToRunFor >= 0))
93 Thread::sleep (1);
94 }
95 JUCE_CATCH_EXCEPTION
96
97 if (millisecondsToRunFor >= 0 && Time::currentTimeMillis() >= endTime)
98 break;
99 }
100
101 return quitMessageReceived.get() == 0;
102}
103#endif
104
105#if ! (JUCE_MAC || JUCE_IOS || JUCE_ANDROID)
106class MessageManager::QuitMessage : public MessageManager::MessageBase
107{
108public:
109 QuitMessage() {}
110
111 void messageCallback() override
112 {
113 if (auto* mm = MessageManager::instance)
114 mm->quitMessageReceived = true;
115 }
116
117 JUCE_DECLARE_NON_COPYABLE (QuitMessage)
118};
119
121{
122 jassert (isThisTheMessageThread()); // must only be called by the message thread
123
124 while (quitMessageReceived.get() == 0)
125 {
126 JUCE_TRY
127 {
128 if (! dispatchNextMessageOnSystemQueue (false))
129 Thread::sleep (1);
130 }
131 JUCE_CATCH_EXCEPTION
132 }
133}
134
136{
137 (new QuitMessage())->post();
138 quitMessagePosted = true;
139}
140
141#endif
142
143//==============================================================================
145{
146public:
147 AsyncFunctionCallback (MessageCallbackFunction* const f, void* const param)
148 : func (f), parameter (param)
149 {}
150
151 void messageCallback() override
152 {
153 result = (*func) (parameter);
154 finished.signal();
155 }
156
157 WaitableEvent finished;
158 std::atomic<void*> result { nullptr };
159
160private:
161 MessageCallbackFunction* const func;
162 void* const parameter;
163
164 JUCE_DECLARE_NON_COPYABLE (AsyncFunctionCallback)
165};
166
167void* MessageManager::callFunctionOnMessageThread (MessageCallbackFunction* func, void* parameter)
168{
170 return func (parameter);
171
172 // If this thread has the message manager locked, then this will deadlock!
174
176
177 if (message->post())
178 {
179 message->finished.wait();
180 return message->result.load();
181 }
182
183 jassertfalse; // the OS message queue failed to send the message!
184 return nullptr;
185}
186
187bool MessageManager::callAsync (std::function<void()> fn)
188{
189 struct AsyncCallInvoker : public MessageBase
190 {
191 AsyncCallInvoker (std::function<void()> f) : callback (std::move (f)) {}
192 void messageCallback() override { callback(); }
193 std::function<void()> callback;
194 };
195
196 return (new AsyncCallInvoker (std::move (fn)))->post();
197}
198
199//==============================================================================
200void MessageManager::deliverBroadcastMessage (const String& value)
201{
202 if (broadcaster != nullptr)
203 broadcaster->sendActionMessage (value);
204}
205
207{
208 if (broadcaster == nullptr)
209 broadcaster.reset (new ActionBroadcaster());
210
211 broadcaster->addActionListener (listener);
212}
213
215{
216 if (broadcaster != nullptr)
217 broadcaster->removeActionListener (listener);
218}
219
220//==============================================================================
222{
223 return Thread::getCurrentThreadId() == messageThreadId;
224}
225
227{
228 auto thisThread = Thread::getCurrentThreadId();
229
230 if (messageThreadId != thisThread)
231 {
232 messageThreadId = thisThread;
233
234 // This is needed on windows to make sure the message window is created by this thread
235 doPlatformSpecificShutdown();
236 doPlatformSpecificInitialisation();
237 }
238}
239
241{
242 auto thisThread = Thread::getCurrentThreadId();
243 return thisThread == messageThreadId || thisThread == threadWithLock.get();
244}
245
247{
248 if (auto i = getInstanceWithoutCreating())
249 return i->currentThreadHasLockedMessageManager();
250
251 return false;
252}
253
255{
256 if (auto i = getInstanceWithoutCreating())
257 return i->isThisTheMessageThread();
258
259 return false;
260}
261
262//==============================================================================
263//==============================================================================
264/* The only safe way to lock the message thread while another thread does
265 some work is by posting a special message, whose purpose is to tie up the event
266 loop until the other thread has finished its business.
267
268 Any other approach can get horribly deadlocked if the OS uses its own hidden locks which
269 get locked before making an event callback, because if the same OS lock gets indirectly
270 accessed from another thread inside a MM lock, you're screwed. (this is exactly what happens
271 in Cocoa).
272*/
274{
275 BlockingMessage (const MessageManager::Lock* parent) noexcept
276 : owner (parent)
277 {}
278
279 void messageCallback() override
280 {
281 {
282 ScopedLock lock (ownerCriticalSection);
283
284 if (auto* o = owner.get())
285 o->messageCallback();
286 }
287
288 releaseEvent.wait();
289 }
290
291 CriticalSection ownerCriticalSection;
293 WaitableEvent releaseEvent;
294
295 JUCE_DECLARE_NON_COPYABLE (BlockingMessage)
296};
297
298//==============================================================================
301void MessageManager::Lock::enter() const noexcept { tryAcquire (true); }
302bool MessageManager::Lock::tryEnter() const noexcept { return tryAcquire (false); }
303
304bool MessageManager::Lock::tryAcquire (bool lockIsMandatory) const noexcept
305{
306 auto* mm = MessageManager::instance;
307
308 if (mm == nullptr)
309 {
310 jassertfalse;
311 return false;
312 }
313
314 if (! lockIsMandatory && (abortWait.get() != 0))
315 {
316 abortWait.set (0);
317 return false;
318 }
319
320 if (mm->currentThreadHasLockedMessageManager())
321 return true;
322
323 try
324 {
325 blockingMessage = *new BlockingMessage (this);
326 }
327 catch (...)
328 {
329 jassert (! lockIsMandatory);
330 return false;
331 }
332
333 if (! blockingMessage->post())
334 {
335 // post of message failed while trying to get the lock
336 jassert (! lockIsMandatory);
337 blockingMessage = nullptr;
338 return false;
339 }
340
341 do
342 {
343 while (abortWait.get() == 0)
344 lockedEvent.wait (-1);
345
346 abortWait.set (0);
347
348 if (lockGained.get() != 0)
349 {
350 mm->threadWithLock = Thread::getCurrentThreadId();
351 return true;
352 }
353
354 } while (lockIsMandatory);
355
356 // we didn't get the lock
357 blockingMessage->releaseEvent.signal();
358
359 {
360 ScopedLock lock (blockingMessage->ownerCriticalSection);
361
362 lockGained.set (0);
363 blockingMessage->owner.set (nullptr);
364 }
365
366 blockingMessage = nullptr;
367 return false;
368}
369
370void MessageManager::Lock::exit() const noexcept
371{
372 if (lockGained.compareAndSetBool (false, true))
373 {
374 auto* mm = MessageManager::instance;
375
376 jassert (mm == nullptr || mm->currentThreadHasLockedMessageManager());
377 lockGained.set (0);
378
379 if (mm != nullptr)
380 mm->threadWithLock = {};
381
382 if (blockingMessage != nullptr)
383 {
384 blockingMessage->releaseEvent.signal();
385 blockingMessage = nullptr;
386 }
387 }
388}
389
390void MessageManager::Lock::messageCallback() const
391{
392 lockGained.set (1);
393 abort();
394}
395
396void MessageManager::Lock::abort() const noexcept
397{
398 abortWait.set (1);
399 lockedEvent.signal();
400}
401
402//==============================================================================
404 : locked (attemptLock (threadToCheck, nullptr))
405{}
406
408 : locked (attemptLock (nullptr, jobToCheck))
409{}
410
411bool MessageManagerLock::attemptLock (Thread* threadToCheck, ThreadPoolJob* jobToCheck)
412{
413 jassert (threadToCheck == nullptr || jobToCheck == nullptr);
414
415 if (threadToCheck != nullptr)
416 threadToCheck->addListener (this);
417
418 if (jobToCheck != nullptr)
419 jobToCheck->addListener (this);
420
421 // tryEnter may have a spurious abort (return false) so keep checking the condition
422 while ((threadToCheck == nullptr || ! threadToCheck->threadShouldExit())
423 && (jobToCheck == nullptr || ! jobToCheck->shouldExit()))
424 {
425 if (mmLock.tryEnter())
426 break;
427 }
428
429 if (threadToCheck != nullptr)
430 {
431 threadToCheck->removeListener (this);
432
433 if (threadToCheck->threadShouldExit())
434 return false;
435 }
436
437 if (jobToCheck != nullptr)
438 {
439 jobToCheck->removeListener (this);
440
441 if (jobToCheck->shouldExit())
442 return false;
443 }
444
445 return true;
446}
447
449
450void MessageManagerLock::exitSignalSent()
451{
452 mmLock.abort();
453}
454
455//==============================================================================
456JUCE_API void JUCE_CALLTYPE initialiseJuce_GUI();
457JUCE_API void JUCE_CALLTYPE initialiseJuce_GUI()
458{
459 JUCE_AUTORELEASEPOOL
460 {
462 }
463}
464
465JUCE_API void JUCE_CALLTYPE shutdownJuce_GUI();
466JUCE_API void JUCE_CALLTYPE shutdownJuce_GUI()
467{
468 JUCE_AUTORELEASEPOOL
469 {
472 }
473}
474
475static int numScopedInitInstances = 0;
476
477ScopedJuceInitialiser_GUI::ScopedJuceInitialiser_GUI() { if (numScopedInitInstances++ == 0) initialiseJuce_GUI(); }
478ScopedJuceInitialiser_GUI::~ScopedJuceInitialiser_GUI() { if (--numScopedInitInstances == 0) shutdownJuce_GUI(); }
479
480} // namespace juce
Manages a list of ActionListeners, and can send them messages.
Interface class for delivery of events that are sent by an ActionBroadcaster.
A re-entrant mutex.
static void deleteAll()
Deletes all extant objects.
Automatically locks and unlocks a mutex object.
static bool isStandaloneApp() noexcept
Returns true if this executable is running as an app (as opposed to being a plugin or other kind of s...
~MessageManagerLock() override
Releases the current thread's lock on the message manager.
MessageManagerLock(Thread *threadToCheckForExitSignal=nullptr)
Tries to acquire a lock on the message manager.
A lock you can use to lock the message manager.
Lock()
Creates a new critical section to exclusively access methods which can only be called when the messag...
void enter() const noexcept
Acquires the message manager lock.
void abort() const noexcept
Unblocks a thread which is waiting in tryEnter Call this method if you want to unblock a thread which...
bool tryEnter() const noexcept
Attempts to lock the message manager and exits if abort is called.
void exit() const noexcept
Releases the message manager lock.
Internal class used as the base class for all message objects.
This class is in charge of the application's event-dispatch loop.
static bool callAsync(std::function< void()> functionToCall)
Asynchronously invokes a function or C++11 lambda on the message thread.
bool runDispatchLoopUntil(int millisecondsToRunFor)
Synchronously dispatches messages until a given time has elapsed.
bool isThisTheMessageThread() const noexcept
Returns true if the caller-thread is the message thread.
static bool existsAndIsCurrentThread() noexcept
Returns true if there's an instance of the MessageManager, and if the current thread is running it.
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 currentThreadHasLockedMessageManager() const noexcept
Returns true if the caller thread has currently got the message manager locked.
void * callFunctionOnMessageThread(MessageCallbackFunction *callback, void *userData)
Calls a function using the message-thread.
void deregisterBroadcastListener(ActionListener *listener)
Deregisters a broadcast listener.
void setCurrentThreadAsMessageThread()
Called to tell the manager that the current thread is the one that's running the dispatch loop.
static bool existsAndIsLockedByCurrentThread() noexcept
Returns true if there's an instance of the MessageManager, and if the current thread has the lock on ...
void registerBroadcastListener(ActionListener *listener)
Registers a listener to get told about broadcast messages.
static void deleteInstance()
Deletes the global MessageManager instance.
static MessageManager * getInstanceWithoutCreating() noexcept
Returns the global instance of the MessageManager, or nullptr if it doesn't exist.
static MessageManager * getInstance()
Returns the global instance of the MessageManager.
A smart-pointer class which points to a reference-counted object.
~ScopedJuceInitialiser_GUI()
The destructor simply calls shutdownJuce_GUI().
ScopedJuceInitialiser_GUI()
The constructor simply calls initialiseJuce_GUI().
The JUCE String class!
Definition: juce_String.h:43
A task that is executed by a ThreadPool object.
void addListener(Thread::Listener *)
Add a listener to this thread job which will receive a callback when signalJobShouldExit was called o...
bool shouldExit() const noexcept
Returns true if something is trying to interrupt this job and make it stop.
void removeListener(Thread::Listener *)
Removes a listener added with addListener.
Encapsulates a thread.
Definition: juce_Thread.h:47
static void JUCE_CALLTYPE sleep(int milliseconds)
Suspends the execution of the current thread until the specified timeout period has elapsed (note tha...
static void JUCE_CALLTYPE setCurrentThreadName(const String &newThreadName)
Changes the name of the caller thread.
bool threadShouldExit() const
Checks whether the thread has been told to stop running.
static ThreadID JUCE_CALLTYPE getCurrentThreadId()
Returns an id that identifies the caller thread.
void addListener(Listener *)
Add a listener to this thread which will receive a callback when signalThreadShouldExit was called on...
void removeListener(Listener *)
Removes a listener added with addListener.
static int64 currentTimeMillis() noexcept
Returns the current system time.
Definition: juce_Time.cpp:205
Allows threads to wait for events triggered by other threads.
#define JUCE_API
This macro is added to all JUCE public class declarations.
A simple wrapper around std::atomic.
Definition: juce_Atomic.h:46
Type get() const noexcept
Atomically reads and returns the current value.
Definition: juce_Atomic.h:68