ThreadWeaver 5.109.0
Signals | Public Member Functions | Protected Member Functions | List of all members
ThreadWeaver::Weaver

A Weaver manages worker threads. More...

#include <weaver.h>

Signals

void threadExited (ThreadWeaver::Thread *)
 A thread has exited.
 
void threadStarted (ThreadWeaver::Thread *)
 A Thread has been created.
 
void threadSuspended (ThreadWeaver::Thread *)
 A thread has been suspended.
 

Public Member Functions

 Weaver (QObject *parent=nullptr)
 
int activeThreadCount ()
 
JobPointer applyForWork (Thread *thread, bool wasBusy) override
 
void blockThreadUntilJobsAreBeingAssigned (Thread *th)
 
void blockThreadUntilJobsAreBeingAssigned_locked (Thread *th)
 
int currentNumberOfThreads () const override
 Returns the current number of threads in the inventory.
 
int currentNumberOfThreads_p () const override
 
void decActiveThreadCount ()
 
void dequeue () override
 Remove all queued jobs.
 
bool dequeue (const JobPointer &job) override
 Remove a job from the queue.
 
void dequeue_p () override
 
bool dequeue_p (JobPointer job) override
 
void enqueue (const QVector< JobPointer > &jobs) override
 Queue a vector of jobs.
 
void enqueue_p (const QVector< JobPointer > &jobs)
 
void finish () override
 Finish all queued operations, then return.
 
void finish_p () override
 
void incActiveThreadCount ()
 
bool isEmpty () const override
 Is the queue empty? The queue is empty if no more jobs are queued.
 
bool isEmpty_p () const override
 
bool isIdle () const override
 Is the weaver idle? The weaver is idle if no jobs are queued and no jobs are processed by the threads.
 
bool isIdle_p () const override
 
int maximumNumberOfThreads () const override
 Get the maximum number of threads this Weaver may start.
 
int maximumNumberOfThreads_p () const override
 
int queueLength () const override
 Returns the number of pending jobs.
 
int queueLength_p () const override
 
void requestAbort () override
 Request aborts of the currently executed jobs.
 
void requestAbort_p () override
 
void reschedule () override
 Reschedule the jobs in the queue.
 
void resume () override
 Resume job queueing.
 
void resume_p () override
 
void setMaximumNumberOfThreads (int cap) override
 Set the maximum number of threads this Weaver object may start.
 
void setMaximumNumberOfThreads_p (int cap) override
 
void setState (StateId)
 
void setState_p (StateId)
 
void shutDown () override
 Shut down the queue.
 
void shutDown_p () override
 
const Statestate () const override
 Return the state of the weaver object.
 
Statestate () override
 
void suspend () override
 Suspend job execution.
 
void suspend_p () override
 
JobPointer takeFirstAvailableJobOrSuspendOrWait (Thread *th, bool threadWasBusy, bool suspendIfAllThreadsInactive, bool justReturning)
 
void threadEnteredRun (Thread *thread)
 
void waitForAvailableJob (Thread *th) override
 

Protected Member Functions

void adjustActiveThreadCount (int diff)
 
void adjustInventory (int noOfNewJobs)
 
virtual ThreadcreateThread ()
 

Detailed Description

A Weaver manages worker threads.

It creates an inventory of Thread objects to which it assigns jobs from its queue. It extends the API of Queue, hiding methods that need to be public to implement state handling, but should not be exposed in general.

Member Function Documentation

◆ currentNumberOfThreads()

int ThreadWeaver::Weaver::currentNumberOfThreads ( ) const
overridevirtual

Returns the current number of threads in the inventory.

Implements ThreadWeaver::QueueInterface.

◆ dequeue() [1/2]

void ThreadWeaver::Weaver::dequeue ( )
overridevirtual

Remove all queued jobs.

All waiting jobs will be dequeued. The semantics are the same as for dequeue(JobInterface).

See also
dequeue(JobInterface)

Implements ThreadWeaver::QueueInterface.

◆ dequeue() [2/2]

bool ThreadWeaver::Weaver::dequeue ( const JobPointer &  job)
overridevirtual

Remove a job from the queue.

If the job was queued but not started so far, it is removed from the queue.

You can always call dequeue, it will return true if the job was dequeued. However if the job is not in the queue anymore, it is already being executed, it is too late to dequeue, and dequeue will return false. The return value is thread-safe - if true is returned, the job was still waiting, and has been dequeued. If not, the job was not waiting in the queue.

Modifying queued jobs is best done on a suspended queue. Often, for example at the end of an application, it is sufficient to dequeue all jobs (which leaves only the ones mid-air in threads), call finish (that will wait for all the mid air jobs to complete), and then exit. Without dequeue(), all jobs in the queue would be executed during finish().

See also
requestAbort for aborting jobs during execution
Returns
true if the job was waiting and has been dequeued
false if the job was not found waiting in the queue

Implements ThreadWeaver::QueueInterface.

◆ enqueue()

void ThreadWeaver::Weaver::enqueue ( const QVector< JobPointer > &  jobs)
overridevirtual

Queue a vector of jobs.

It depends on the state if execution of the job will be attempted immediately. In suspended state, jobs can be added to the queue, but the threads remain suspended. In WorkongHard state, an idle thread may immediately execute the job, or it might be queued if all threads are busy.

JobPointer is a shared pointer. This means the object pointed to will be deleted if this object is the last remaining reference to it. Keep a JobPointer to the job to avoid automatic deletion.

Implements ThreadWeaver::QueueInterface.

◆ finish()

void ThreadWeaver::Weaver::finish ( )
overridevirtual

Finish all queued operations, then return.

This method is used in imperative (not event driven) programs that cannot react on events to have the controlling (main) thread wait wait for the jobs to finish. The call will block the calling thread and return when all queued jobs have been processed.

Warning: This will suspend your thread! Warning: If one of your jobs enters an infinite loop, this will never return!

Implements ThreadWeaver::QueueInterface.

◆ isEmpty()

bool ThreadWeaver::Weaver::isEmpty ( ) const
overridevirtual

Is the queue empty? The queue is empty if no more jobs are queued.

Implements ThreadWeaver::QueueInterface.

◆ isIdle()

bool ThreadWeaver::Weaver::isIdle ( ) const
overridevirtual

Is the weaver idle? The weaver is idle if no jobs are queued and no jobs are processed by the threads.

Implements ThreadWeaver::QueueInterface.

◆ maximumNumberOfThreads()

int ThreadWeaver::Weaver::maximumNumberOfThreads ( ) const
overridevirtual

Get the maximum number of threads this Weaver may start.

Implements ThreadWeaver::QueueInterface.

◆ queueLength()

int ThreadWeaver::Weaver::queueLength ( ) const
overridevirtual

Returns the number of pending jobs.

This will return the number of queued jobs. Jobs that are currently being executed are not part of the queue. All jobs in the queue are waiting to be executed.

Implements ThreadWeaver::QueueInterface.

◆ requestAbort()

void ThreadWeaver::Weaver::requestAbort ( )
overridevirtual

Request aborts of the currently executed jobs.

It is important to understand that aborts are requested, but cannot be guaranteed, as not all Job classes support it. It is up to the application to decide if and how job aborts are necessary.

Implements ThreadWeaver::QueueInterface.

◆ reschedule()

void ThreadWeaver::Weaver::reschedule ( )
overridevirtual

Reschedule the jobs in the queue.

This method triggers a scheduling attempt to perform jobs. It will schedule enqueued jobs to be executed by idle threads. It should only be necessary to call it if the canRun() status of a job changed spontaneously due to external reasons.

Implements ThreadWeaver::QueueInterface.

◆ resume()

void ThreadWeaver::Weaver::resume ( )
overridevirtual

Resume job queueing.

See also
suspend

Implements ThreadWeaver::QueueInterface.

◆ setMaximumNumberOfThreads()

void ThreadWeaver::Weaver::setMaximumNumberOfThreads ( int  cap)
overridevirtual

Set the maximum number of threads this Weaver object may start.

Implements ThreadWeaver::QueueInterface.

◆ shutDown()

void ThreadWeaver::Weaver::shutDown ( )
overridevirtual

Shut down the queue.

Tells all threads to exit, and changes to Destructed state. It is safe to destroy the queue once this method returns.

Implements ThreadWeaver::QueueInterface.

◆ state()

const State * ThreadWeaver::Weaver::state ( ) const
overridevirtual

Return the state of the weaver object.

Implements ThreadWeaver::QueueInterface.

◆ suspend()

void ThreadWeaver::Weaver::suspend ( )
overridevirtual

Suspend job execution.

When suspending, all threads are allowed to finish the currently assigned job but will not receive a new assignment. When all threads are done processing the assigned job, the signal suspended will() be emitted. If you call suspend() and there are no jobs left to be done, you will immediately receive the suspended() signal.

Implements ThreadWeaver::QueueInterface.

◆ threadExited

void ThreadWeaver::Weaver::threadExited ( ThreadWeaver::Thread )
signal

A thread has exited.

◆ threadStarted

void ThreadWeaver::Weaver::threadStarted ( ThreadWeaver::Thread )
signal

A Thread has been created.

◆ threadSuspended

void ThreadWeaver::Weaver::threadSuspended ( ThreadWeaver::Thread )
signal

A thread has been suspended.