ThreadWeaver::Weaver

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#include <weaver.h>

Inherits ThreadWeaver::QueueAPI.

Signals

void threadExited (ThreadWeaver::Thread *)
 
void threadStarted (ThreadWeaver::Thread *)
 
void threadSuspended (ThreadWeaver::Thread *)
 

Public Member Functions

 Weaver (QObject *parent=nullptr)
 
 ~Weaver () override
 
int activeThreadCount ()
 
JobPointer applyForWork (Thread *thread, bool wasBusy) override
 
void blockThreadUntilJobsAreBeingAssigned (Thread *th)
 
void blockThreadUntilJobsAreBeingAssigned_locked (Thread *th)
 
int currentNumberOfThreads () const override
 
int currentNumberOfThreads_p () const override
 
void decActiveThreadCount ()
 
void dequeue () override
 
bool dequeue (const JobPointer &job) override
 
void dequeue_p () override
 
bool dequeue_p (JobPointer job) override
 
void enqueue (const QVector< JobPointer > &jobs) override
 
void enqueue_p (const QVector< JobPointer > &jobs)
 
void finish () override
 
void finish_p () override
 
void incActiveThreadCount ()
 
bool isEmpty () const override
 
bool isEmpty_p () const override
 
bool isIdle () const override
 
bool isIdle_p () const override
 
int maximumNumberOfThreads () const override
 
int maximumNumberOfThreads_p () const override
 
int queueLength () const override
 
int queueLength_p () const override
 
void requestAbort () override
 
void requestAbort_p () override
 
void reschedule () override
 
void resume () override
 
void resume_p () override
 
void setMaximumNumberOfThreads (int cap) override
 
void setMaximumNumberOfThreads_p (int cap) override
 
void setState (StateId)
 
void setState_p (StateId)
 
void shutDown () override
 
void shutDown_p () override
 
const Statestate () const override
 
Statestate () override
 
void suspend () override
 
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.

Definition at line 34 of file weaver.h.

Constructor & Destructor Documentation

◆ Weaver()

Weaver::Weaver ( QObject parent = nullptr)
explicit

Constructs a Weaver object.

Definition at line 36 of file weaver.cpp.

◆ ~Weaver()

Weaver::~Weaver ( )
override

Destructs a Weaver object.

Definition at line 55 of file weaver.cpp.

Member Function Documentation

◆ activeThreadCount()

int Weaver::activeThreadCount ( )

Returns the number of active threads.

Threads are active if they process a job. Requires that the mutex is being held when called.

Definition at line 482 of file weaver.cpp.

◆ adjustActiveThreadCount()

void Weaver::adjustActiveThreadCount ( int  diff)
protected

Adjust active thread count.

This is a helper function for incActiveThreadCount and decActiveThreadCount.

Definition at line 462 of file weaver.cpp.

◆ adjustInventory()

void Weaver::adjustInventory ( int  numberOfNewJobs)
protected

Adjust the inventory size.

Requires that the mutex is being held when called.

This method creates threads on demand. Threads in the inventory are not created upon construction of the WeaverImpl object, but when jobs are queued. This avoids costly delays on the application startup time. Threads are created when the inventory size is under inventoryMin and new jobs are queued.

Definition at line 403 of file weaver.cpp.

◆ applyForWork()

JobPointer Weaver::applyForWork ( Thread th,
bool  wasBusy 
)
override

Assign a job to the calling thread.

This is supposed to be called from the Thread objects in the inventory. Do not call this method from your code. Returns 0 if the weaver is shutting down, telling the calling thread to finish and exit. If no jobs are available and shut down is not in progress, the calling thread is suspended until either condition is met.

Parameters
wasBusyTrue if the thread is returning from processing a job

Definition at line 573 of file weaver.cpp.

◆ blockThreadUntilJobsAreBeingAssigned()

void Weaver::blockThreadUntilJobsAreBeingAssigned ( Thread th)

Blocks the calling thread until jobs can be assigned.

Definition at line 585 of file weaver.cpp.

◆ blockThreadUntilJobsAreBeingAssigned_locked()

void Weaver::blockThreadUntilJobsAreBeingAssigned_locked ( Thread th)

Blocks the calling thread until jobs can be assigned.

The mutex must be held when calling this method.

Definition at line 596 of file weaver.cpp.

◆ createThread()

Thread * Weaver::createThread ( )
protectedvirtual

Factory method to create the threads.

Overload in adapted Weaver implementations.

Definition at line 438 of file weaver.cpp.

◆ currentNumberOfThreads()

int Weaver::currentNumberOfThreads ( ) const
overridevirtual

Returns the current number of threads in the inventory.

Implements ThreadWeaver::QueueInterface.

Definition at line 190 of file weaver.cpp.

◆ decActiveThreadCount()

void Weaver::decActiveThreadCount ( )

brief Decrement the count of active threads.

Definition at line 450 of file weaver.cpp.

◆ dequeue() [1/2]

void 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.

Definition at line 266 of file weaver.cpp.

◆ dequeue() [2/2]

bool 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.

Definition at line 238 of file weaver.cpp.

◆ enqueue()

void 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.

Definition at line 203 of file weaver.cpp.

◆ finish()

void 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.

Definition at line 284 of file weaver.cpp.

◆ incActiveThreadCount()

void Weaver::incActiveThreadCount ( )

Increment the count of active threads.

Definition at line 444 of file weaver.cpp.

◆ isEmpty()

bool Weaver::isEmpty ( ) const
overridevirtual

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

Implements ThreadWeaver::QueueInterface.

Definition at line 334 of file weaver.cpp.

◆ isIdle()

bool 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.

Definition at line 347 of file weaver.cpp.

◆ maximumNumberOfThreads()

int Weaver::maximumNumberOfThreads ( ) const
overridevirtual

Get the maximum number of threads this Weaver may start.

Implements ThreadWeaver::QueueInterface.

Definition at line 177 of file weaver.cpp.

◆ queueLength()

int 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.

Definition at line 360 of file weaver.cpp.

◆ requestAbort()

void 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.

Definition at line 373 of file weaver.cpp.

◆ reschedule()

void 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.

Definition at line 380 of file weaver.cpp.

◆ resume()

void Weaver::resume ( )
overridevirtual

Resume job queueing.

See also
suspend

Implements ThreadWeaver::QueueInterface.

Definition at line 322 of file weaver.cpp.

◆ setMaximumNumberOfThreads()

void Weaver::setMaximumNumberOfThreads ( int  cap)
overridevirtual

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

Implements ThreadWeaver::QueueInterface.

Definition at line 158 of file weaver.cpp.

◆ setState()

void Weaver::setState ( StateId  id)

Set the Weaver state.

See also
StateId
WeaverImplState
State

Definition at line 126 of file weaver.cpp.

◆ shutDown()

void Weaver::shutDown ( )
overridevirtual

Enter Destructed state.

Once this method returns, it is save to delete this object.

Implements ThreadWeaver::QueueInterface.

Definition at line 64 of file weaver.cpp.

◆ state()

State * Weaver::state ( ) const
overridevirtual

Return the state of the weaver object.

Implements ThreadWeaver::QueueInterface.

Definition at line 148 of file weaver.cpp.

◆ suspend()

void 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.

Definition at line 310 of file weaver.cpp.

◆ takeFirstAvailableJobOrSuspendOrWait()

JobPointer Weaver::takeFirstAvailableJobOrSuspendOrWait ( Thread th,
bool  threadWasBusy,
bool  suspendIfInactive,
bool  justReturning 
)

Take the first available job out of the queue and return it.

The job will be removed from the queue (therefore, take). Only jobs that have no unresolved dependencies are considered available. If only jobs that depend on other unfinished jobs are in the queue, this method blocks on m_jobAvailable.

This method will enter suspended state if the active thread count is now zero and suspendIfAllThreadsInactive is true. If justReturning is true, do not assign a new job, just process the completed previous one.

Definition at line 505 of file weaver.cpp.

◆ threadEnteredRun()

void Weaver::threadEnteredRun ( Thread thread)

Called from a new thread when entering the run method.

Definition at line 489 of file weaver.cpp.

◆ 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.

◆ waitForAvailableJob()

void Weaver::waitForAvailableJob ( Thread th)
override

Wait for a job to become available.

Definition at line 579 of file weaver.cpp.


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