A set of threads that will run a list of jobs. More...

Classes

class  JobSelector
 A callback class used when you need to select which ThreadPoolJob objects are suitable for some kind of operation. More...
 

Public Member Functions

 ThreadPool (int numberOfThreads, size_t threadStackSize=0)
 Creates a thread pool. More...
 
 ThreadPool ()
 Creates a thread pool with one thread per CPU core. More...
 
 ~ThreadPool ()
 Destructor. More...
 
void addJob (ThreadPoolJob *job, bool deleteJobWhenFinished)
 Adds a job to the queue. More...
 
void addJob (std::function< ThreadPoolJob::JobStatus()> job)
 Adds a lambda function to be called as a job. More...
 
void addJob (std::function< void()> job)
 Adds a lambda function to be called as a job. More...
 
bool removeJob (ThreadPoolJob *job, bool interruptIfRunning, int timeOutMilliseconds)
 Tries to remove a job from the pool. More...
 
bool removeAllJobs (bool interruptRunningJobs, int timeOutMilliseconds, JobSelector *selectedJobsToRemove=nullptr)
 Tries to remove all jobs from the pool. More...
 
int getNumJobs () const noexcept
 Returns the number of jobs currently running or queued. More...
 
int getNumThreads () const noexcept
 Returns the number of threads assigned to this thread pool. More...
 
ThreadPoolJobgetJob (int index) const noexcept
 Returns one of the jobs in the queue. More...
 
bool contains (const ThreadPoolJob *job) const noexcept
 Returns true if the given job is currently queued or running. More...
 
bool isJobRunning (const ThreadPoolJob *job) const noexcept
 Returns true if the given job is currently being run by a thread. More...
 
bool waitForJobToFinish (const ThreadPoolJob *job, int timeOutMilliseconds) const
 Waits until a job has finished running and has been removed from the pool. More...
 
void moveJobToFront (const ThreadPoolJob *jobToMove) noexcept
 If the given job is in the queue, this will move it to the front so that it is the next one to be executed. More...
 
StringArray getNamesOfAllJobs (bool onlyReturnActiveJobs) const
 Returns a list of the names of all the jobs currently running or queued. More...
 
bool setThreadPriorities (int newPriority)
 Changes the priority of all the threads. More...
 

Detailed Description

A set of threads that will run a list of jobs.

When a ThreadPoolJob object is added to the ThreadPool's list, its runJob() method will be called by the next pooled thread that becomes free.

See also
ThreadPoolJob, Thread

Constructor & Destructor Documentation

◆ ThreadPool() [1/2]

ThreadPool::ThreadPool ( int  numberOfThreads,
size_t  threadStackSize = 0 
)

Creates a thread pool.

Once you've created a pool, you can give it some jobs by calling addJob().

Parameters
numberOfThreadsthe number of threads to run. These will be started immediately, and will run until the pool is deleted.
threadStackSizethe size of the stack of each thread. If this value is zero then the default stack size of the OS will be used.

◆ ThreadPool() [2/2]

ThreadPool::ThreadPool ( )

Creates a thread pool with one thread per CPU core.

Once you've created a pool, you can give it some jobs by calling addJob(). If you want to specify the number of threads, use the other constructor; this one creates a pool which has one thread for each CPU core.

See also
SystemStats::getNumCpus()

◆ ~ThreadPool()

ThreadPool::~ThreadPool ( )

Destructor.

This will attempt to remove all the jobs before deleting, but if you want to specify a timeout, you should call removeAllJobs() explicitly before deleting the pool.

Member Function Documentation

◆ addJob() [1/3]

void ThreadPool::addJob ( ThreadPoolJob job,
bool  deleteJobWhenFinished 
)

Adds a job to the queue.

Once a job has been added, then the next time a thread is free, it will run the job's ThreadPoolJob::runJob() method. Depending on the return value of the runJob() method, the pool will either remove the job from the pool or add it to the back of the queue to be run again.

If deleteJobWhenFinished is true, then the job object will be owned and deleted by the pool when not needed - if you do this, make sure that your object's destructor is thread-safe.

If deleteJobWhenFinished is false, the pointer will be used but not deleted, and the caller is responsible for making sure the object is not deleted before it has been removed from the pool.

◆ addJob() [2/3]

void ThreadPool::addJob ( std::function< ThreadPoolJob::JobStatus()>  job)

Adds a lambda function to be called as a job.

This will create an internal ThreadPoolJob object to encapsulate and call the lambda.

◆ addJob() [3/3]

void ThreadPool::addJob ( std::function< void()>  job)

Adds a lambda function to be called as a job.

This will create an internal ThreadPoolJob object to encapsulate and call the lambda.

◆ removeJob()

bool ThreadPool::removeJob ( ThreadPoolJob job,
bool  interruptIfRunning,
int  timeOutMilliseconds 
)

Tries to remove a job from the pool.

If the job isn't yet running, this will simply remove it. If it is running, it will wait for it to finish.

If the timeout period expires before the job finishes running, then the job will be left in the pool and this will return false. It returns true if the job is successfully stopped and removed.

Parameters
jobthe job to remove
interruptIfRunningif true, then if the job is currently busy, its ThreadPoolJob::signalJobShouldExit() method will be called to try to interrupt it. If false, then if the job will be allowed to run until it stops normally (or the timeout expires)
timeOutMillisecondsthe length of time this method should wait for the job to finish before giving up and returning false

◆ removeAllJobs()

bool ThreadPool::removeAllJobs ( bool  interruptRunningJobs,
int  timeOutMilliseconds,
JobSelector selectedJobsToRemove = nullptr 
)

Tries to remove all jobs from the pool.

Parameters
interruptRunningJobsif true, then all running jobs will have their ThreadPoolJob::signalJobShouldExit() methods called to try to interrupt them
timeOutMillisecondsthe length of time this method should wait for all the jobs to finish before giving up and returning false
selectedJobsToRemoveif this is not a nullptr, the JobSelector object is asked to decide which jobs should be removed. If it is a nullptr, all jobs are removed
Returns
true if all jobs are successfully stopped and removed; false if the timeout period expires while waiting for one or more jobs to stop

◆ getNumJobs()

int ThreadPool::getNumJobs ( ) const
noexcept

Returns the number of jobs currently running or queued.

◆ getNumThreads()

int ThreadPool::getNumThreads ( ) const
noexcept

Returns the number of threads assigned to this thread pool.

◆ getJob()

ThreadPoolJob* ThreadPool::getJob ( int  index) const
noexcept

Returns one of the jobs in the queue.

Note that this can be a very volatile list as jobs might be continuously getting shifted around in the list, and this method may return nullptr if the index is currently out-of-range.

◆ contains()

bool ThreadPool::contains ( const ThreadPoolJob job) const
noexcept

Returns true if the given job is currently queued or running.

See also
isJobRunning()

◆ isJobRunning()

bool ThreadPool::isJobRunning ( const ThreadPoolJob job) const
noexcept

Returns true if the given job is currently being run by a thread.

◆ waitForJobToFinish()

bool ThreadPool::waitForJobToFinish ( const ThreadPoolJob job,
int  timeOutMilliseconds 
) const

Waits until a job has finished running and has been removed from the pool.

This will wait until the job is no longer in the pool - i.e. until its runJob() method returns ThreadPoolJob::jobHasFinished.

If the timeout period expires before the job finishes, this will return false; it returns true if the job has finished successfully.

◆ moveJobToFront()

void ThreadPool::moveJobToFront ( const ThreadPoolJob jobToMove)
noexcept

If the given job is in the queue, this will move it to the front so that it is the next one to be executed.

◆ getNamesOfAllJobs()

StringArray ThreadPool::getNamesOfAllJobs ( bool  onlyReturnActiveJobs) const

Returns a list of the names of all the jobs currently running or queued.

If onlyReturnActiveJobs is true, only the ones currently running are returned.

◆ setThreadPriorities()

bool ThreadPool::setThreadPriorities ( int  newPriority)

Changes the priority of all the threads.

This will call Thread::setPriority() for each thread in the pool. May return false if for some reason the priority can't be changed.


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