JUCE  v5.4.1-191-g0ab5e696f
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juce::TimeSliceThread Class Referenceabstract

A thread that keeps a list of clients, and calls each one in turn, giving them all a chance to run some sort of short task. More...

#include <juce_TimeSliceThread.h>

Inheritance diagram for juce::TimeSliceThread:
Collaboration diagram for juce::TimeSliceThread:

Public Types

enum  { realtimeAudioPriority = -1 }
 Special realtime audio thread priority. More...
 
using ThreadID = void *
 A value type used for thread IDs. More...
 

Public Member Functions

 TimeSliceThread (const String &threadName)
 Creates a TimeSliceThread. More...
 
 ~TimeSliceThread () override
 Destructor. More...
 
void addListener (Listener *)
 Add a listener to this thread which will receive a callback when signalThreadShouldExit was called on this thread. More...
 
void addTimeSliceClient (TimeSliceClient *clientToAdd, int millisecondsBeforeStarting=0)
 Adds a client to the list. More...
 
TimeSliceClientgetClient (int index) const
 Returns one of the registered clients. More...
 
int getNumClients () const
 Returns the number of registered clients. More...
 
ThreadID getThreadId () const noexcept
 Returns the ID of this thread. More...
 
const StringgetThreadName () const noexcept
 Returns the name of the thread. More...
 
bool isThreadRunning () const
 Returns true if the thread is currently active. More...
 
void moveToFrontOfQueue (TimeSliceClient *clientToMove)
 If the given client is waiting in the queue, it will be moved to the front and given a time-slice as soon as possible. More...
 
void notify () const
 Wakes up the thread. More...
 
void removeAllClients ()
 Removes all the active and pending clients from the list. More...
 
void removeListener (Listener *)
 Removes a listener added with addListener. More...
 
void removeTimeSliceClient (TimeSliceClient *clientToRemove)
 Removes a client from the list. More...
 
virtual void run ()=0
 Must be implemented to perform the thread's actual code. More...
 
void setAffinityMask (uint32 affinityMask)
 Sets the affinity mask for the thread. More...
 
bool setPriority (int priority)
 Changes the thread's priority. More...
 
void signalThreadShouldExit ()
 Sets a flag to tell the thread it should stop. More...
 
void startThread ()
 Starts the thread running. More...
 
void startThread (int priority)
 Starts the thread with a given priority. More...
 
bool stopThread (int timeOutMilliseconds)
 Attempts to stop the thread running. More...
 
bool threadShouldExit () const
 Checks whether the thread has been told to stop running. More...
 
bool wait (int timeOutMilliseconds) const
 Suspends the execution of this thread until either the specified timeout period has elapsed, or another thread calls the notify() method to wake it up. More...
 
bool waitForThreadToExit (int timeOutMilliseconds) const
 Waits for the thread to stop. More...
 

Static Public Member Functions

static bool currentThreadShouldExit ()
 Checks whether the current thread has been told to stop running. More...
 
static ThreadgetCurrentThread ()
 Finds the thread object that is currently running. More...
 
static ThreadID getCurrentThreadId ()
 Returns an id that identifies the caller thread. More...
 
static void initialiseJUCE (void *jniEnv, void *jContext)
 Initialises the JUCE subsystem for projects not created by the Projucer. More...
 
static void launch (std::function< void()> functionToRun)
 Invokes a lambda or function on its own thread. More...
 
static void setCurrentThreadAffinityMask (uint32 affinityMask)
 Changes the affinity mask for the caller thread. More...
 
static void setCurrentThreadName (const String &newThreadName)
 Changes the name of the caller thread. More...
 
static bool setCurrentThreadPriority (int priority)
 Changes the priority of the caller thread. More...
 
static void sleep (int milliseconds)
 Suspends the execution of the current thread until the specified timeout period has elapsed (note that this may not be exact). More...
 
static void yield ()
 Yields the current thread's CPU time-slot and allows a new thread to run. More...
 

Private Member Functions

TimeSliceClientgetNextClient (int index) const
 

Private Attributes

CriticalSection callbackLock
 
TimeSliceClientclientBeingCalled = nullptr
 
Array< TimeSliceClient * > clients
 
CriticalSection listLock
 

Detailed Description

A thread that keeps a list of clients, and calls each one in turn, giving them all a chance to run some sort of short task.

See also
TimeSliceClient, Thread

{Core}

Member Typedef Documentation

◆ ThreadID

using juce::Thread::ThreadID = void*
inherited

A value type used for thread IDs.

See also
getCurrentThreadId(), getThreadId()

Member Enumeration Documentation

◆ anonymous enum

anonymous enum
inherited

Special realtime audio thread priority.

This priority will create a high-priority thread which is best suited for realtime audio processing.

Currently, this priority is identical to priority 9, except when building for Android with OpenSL/Oboe support.

In this case, JUCE will ask OpenSL/Oboe to construct a super high priority thread specifically for realtime audio processing.

Note that this priority can only be set before the thread has started. Switching to this priority, or from this priority to a different priority, is not supported under Android and will assert.

For best performance this thread should yield at regular intervals and not call any blocking APIs.

See also
startThread, setPriority, sleep, WaitableEvent
Enumerator
realtimeAudioPriority 

Constructor & Destructor Documentation

◆ TimeSliceThread()

juce::TimeSliceThread::TimeSliceThread ( const String threadName)
explicit

Creates a TimeSliceThread.

When first created, the thread is not running. Use the startThread() method to start it.

◆ ~TimeSliceThread()

juce::TimeSliceThread::~TimeSliceThread ( )
override

Destructor.

Deleting a Thread object that is running will only give the thread a brief opportunity to stop itself cleanly, so it's recommended that you should always call stopThread() with a decent timeout before deleting, to avoid the thread being forcibly killed (which is a Bad Thing).

Member Function Documentation

◆ addListener()

void juce::Thread::addListener ( Listener )
inherited

Add a listener to this thread which will receive a callback when signalThreadShouldExit was called on this thread.

See also
signalThreadShouldExit, removeListener

◆ addTimeSliceClient()

void juce::TimeSliceThread::addTimeSliceClient ( TimeSliceClient clientToAdd,
int  millisecondsBeforeStarting = 0 
)

Adds a client to the list.

The client's callbacks will start after the number of milliseconds specified by millisecondsBeforeStarting (and this may happen before this method has returned).

◆ currentThreadShouldExit()

static bool juce::Thread::currentThreadShouldExit ( )
staticinherited

Checks whether the current thread has been told to stop running.

On the message thread, this will always return false, otherwise it will return threadShouldExit() called on the current thread.

See also
threadShouldExit

◆ getClient()

TimeSliceClient* juce::TimeSliceThread::getClient ( int  index) const

Returns one of the registered clients.

◆ getCurrentThread()

static Thread* juce::Thread::getCurrentThread ( )
staticinherited

Finds the thread object that is currently running.

Note that the main UI thread (or other non-JUCE threads) don't have a Thread object associated with them, so this will return nullptr.

◆ getCurrentThreadId()

Thread::ThreadID juce::Thread::getCurrentThreadId ( )
staticinherited

Returns an id that identifies the caller thread.

To find the ID of a particular thread object, use getThreadId().

Returns
a unique identifier that identifies the calling thread.
See also
getThreadId

Referenced by juce::ThreadLocalValue< Type >::get(), and juce::ThreadLocalValue< Type >::releaseCurrentThreadStorage().

◆ getNextClient()

TimeSliceClient* juce::TimeSliceThread::getNextClient ( int  index) const
private

◆ getNumClients()

int juce::TimeSliceThread::getNumClients ( ) const

Returns the number of registered clients.

◆ getThreadId()

ThreadID juce::Thread::getThreadId ( ) const
noexceptinherited

Returns the ID of this thread.

That means the ID of this thread object - not of the thread that's calling the method. This can change when the thread is started and stopped, and will be invalid if the thread's not actually running.

See also
getCurrentThreadId

◆ getThreadName()

const String& juce::Thread::getThreadName ( ) const
inlinenoexceptinherited

Returns the name of the thread.

This is the name that gets set in the constructor.

References JUCE_CALLTYPE.

◆ initialiseJUCE()

static void juce::Thread::initialiseJUCE ( void *  jniEnv,
void *  jContext 
)
staticinherited

Initialises the JUCE subsystem for projects not created by the Projucer.

On Android, JUCE needs to be initialised once before it is used. The Projucer will automatically generate the necessary java code to do this. However, if you are using JUCE without the Projucer or are creating a library made with JUCE intended for use in non-JUCE apks, then you must call this method manually once on apk startup.

You can call this method from C++ or directly from java by calling the following java method:

com.roli.juce.Java.initialiseJUCE (myContext);

Note that the above java method is only available in Android Studio projects created by the Projucer. If you need to call this from another type of project then you need to add the following java file to your project:

package com.roli.juce;
public class Java
{
static { System.loadLibrary ("juce_jni"); }
public native static void initialiseJUCE (Context context);
}
Parameters
jniEnvthis is a pointer to JNI's JNIEnv variable. Any callback from Java into C++ will have this passed in as it's first parameter.
jContextthis is a jobject referring to your app/service/receiver/ provider's Context. JUCE needs this for many of it's internal functions.

◆ isThreadRunning()

bool juce::Thread::isThreadRunning ( ) const
inherited

Returns true if the thread is currently active.

◆ launch()

static void juce::Thread::launch ( std::function< void()>  functionToRun)
staticinherited

Invokes a lambda or function on its own thread.

This will spin up a Thread object which calls the function and then exits. Bear in mind that starting and stopping a thread can be a fairly heavyweight operation, so you might prefer to use a ThreadPool if you're kicking off a lot of short background tasks.

Also note that using an anonymous thread makes it very difficult to interrupt the function when you need to stop it, e.g. when your app quits. So it's up to you to deal with situations where the function may fail to stop in time.

◆ moveToFrontOfQueue()

void juce::TimeSliceThread::moveToFrontOfQueue ( TimeSliceClient clientToMove)

If the given client is waiting in the queue, it will be moved to the front and given a time-slice as soon as possible.

If the specified client has not been added, nothing will happen.

◆ notify()

void juce::Thread::notify ( ) const
inherited

Wakes up the thread.

If the thread has called the wait() method, this will wake it up.

See also
wait

◆ removeAllClients()

void juce::TimeSliceThread::removeAllClients ( )

Removes all the active and pending clients from the list.

This method will make sure that all callbacks to clients have finished before the method returns.

◆ removeListener()

void juce::Thread::removeListener ( Listener )
inherited

Removes a listener added with addListener.

◆ removeTimeSliceClient()

void juce::TimeSliceThread::removeTimeSliceClient ( TimeSliceClient clientToRemove)

Removes a client from the list.

This method will make sure that all callbacks to the client have completely finished before the method returns.

◆ run()

virtual void juce::Thread::run ( )
pure virtualinherited

Must be implemented to perform the thread's actual code.

Remember that the thread must regularly check the threadShouldExit() method whilst running, and if this returns true it should return from the run() method as soon as possible to avoid being forcibly killed.

See also
threadShouldExit, startThread

Implemented in juce::ThreadedAnalyticsDestination::EventDispatcher, juce::MidiOutput, juce::NetworkServiceDiscovery::AvailableServiceList, juce::InterprocessConnectionServer, and juce::NetworkServiceDiscovery::Advertiser.

◆ setAffinityMask()

void juce::Thread::setAffinityMask ( uint32  affinityMask)
inherited

Sets the affinity mask for the thread.

This will only have an effect next time the thread is started - i.e. if the thread is already running when called, it'll have no effect.

See also
setCurrentThreadAffinityMask

◆ setCurrentThreadAffinityMask()

void juce::Thread::setCurrentThreadAffinityMask ( uint32  affinityMask)
staticinherited

Changes the affinity mask for the caller thread.

This will change the affinity mask for the thread that calls this static method.

See also
setAffinityMask

References juce::ignoreUnused(), and jassertfalse.

◆ setCurrentThreadName()

void juce::Thread::setCurrentThreadName ( const String newThreadName)
staticinherited

Changes the name of the caller thread.

Different OSes may place different length or content limits on this name.

References JUCE_AUTORELEASEPOOL, juce::juceStringToNS(), juce::BlocksProtocol::setName, and juce::String::toRawUTF8().

◆ setCurrentThreadPriority()

static bool juce::Thread::setCurrentThreadPriority ( int  priority)
staticinherited

Changes the priority of the caller thread.

Similar to setPriority(), but this static method acts on the caller thread. May return false if for some reason the priority can't be changed.

See also
setPriority

◆ setPriority()

bool juce::Thread::setPriority ( int  priority)
inherited

Changes the thread's priority.

May return false if for some reason the priority can't be changed.

Parameters
prioritythe new priority, in the range 0 (lowest) to 10 (highest). A priority of 5 is normal.
See also
realtimeAudioPriority

◆ signalThreadShouldExit()

void juce::Thread::signalThreadShouldExit ( )
inherited

Sets a flag to tell the thread it should stop.

Calling this means that the threadShouldExit() method will then return true. The thread should be regularly checking this to see whether it should exit.

If your thread makes use of wait(), you might want to call notify() after calling this method, to interrupt any waits that might be in progress, and allow it to reach a point where it can exit.

See also
threadShouldExit, waitForThreadToExit

◆ sleep()

void juce::Thread::sleep ( int  milliseconds)
staticinherited

Suspends the execution of the current thread until the specified timeout period has elapsed (note that this may not be exact).

The timeout period must not be negative and whilst sleeping the thread cannot be woken up so it should only be used for short periods of time and when other methods such as using a WaitableEvent or CriticalSection are not possible.

Referenced by juce::OpenGLContext::NativeContext::initialiseOnRenderThread(), and juce::OpenGLContext::NativeContext::swapBuffers().

◆ startThread() [1/2]

void juce::Thread::startThread ( )
inherited

Starts the thread running.

This will cause the thread's run() method to be called by a new thread. If this thread is already running, startThread() won't do anything.

See also
stopThread

◆ startThread() [2/2]

void juce::Thread::startThread ( int  priority)
inherited

Starts the thread with a given priority.

Launches the thread with a given priority, where 0 = lowest, 10 = highest. If the thread is already running, its priority will be changed.

See also
startThread, setPriority, realtimeAudioPriority

◆ stopThread()

bool juce::Thread::stopThread ( int  timeOutMilliseconds)
inherited

Attempts to stop the thread running.

This method will cause the threadShouldExit() method to return true and call notify() in case the thread is currently waiting.

Hopefully the thread will then respond to this by exiting cleanly, and the stopThread method will wait for a given time-period for this to happen.

If the thread is stuck and fails to respond after the timeout, it gets forcibly killed, which is a very bad thing to happen, as it could still be holding locks, etc. which are needed by other parts of your program.

Parameters
timeOutMillisecondsThe number of milliseconds to wait for the thread to finish before killing it by force. A negative value in here will wait forever.
Returns
true if the thread was cleanly stopped before the timeout, or false if it had to be killed by force.
See also
signalThreadShouldExit, threadShouldExit, waitForThreadToExit, isThreadRunning

◆ threadShouldExit()

bool juce::Thread::threadShouldExit ( ) const
inherited

Checks whether the thread has been told to stop running.

Threads need to check this regularly, and if it returns true, they should return from their run() method at the first possible opportunity.

See also
signalThreadShouldExit, currentThreadShouldExit

◆ wait()

bool juce::Thread::wait ( int  timeOutMilliseconds) const
inherited

Suspends the execution of this thread until either the specified timeout period has elapsed, or another thread calls the notify() method to wake it up.

A negative timeout value means that the method will wait indefinitely.

Returns
true if the event has been signalled, false if the timeout expires.

◆ waitForThreadToExit()

bool juce::Thread::waitForThreadToExit ( int  timeOutMilliseconds) const
inherited

Waits for the thread to stop.

This will wait until isThreadRunning() is false or until a timeout expires.

Parameters
timeOutMillisecondsthe time to wait, in milliseconds. If this value is less than zero, it will wait forever.
Returns
true if the thread exits, or false if the timeout expires first.

◆ yield()

void juce::Thread::yield ( )
staticinherited

Yields the current thread's CPU time-slot and allows a new thread to run.

If there are no other threads of equal or higher priority currently running then this will return immediately and the current thread will continue to run.

Member Data Documentation

◆ callbackLock

CriticalSection juce::TimeSliceThread::callbackLock
private

◆ clientBeingCalled

TimeSliceClient* juce::TimeSliceThread::clientBeingCalled = nullptr
private

◆ clients

Array<TimeSliceClient*> juce::TimeSliceThread::clients
private

◆ listLock

CriticalSection juce::TimeSliceThread::listLock
private

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