PTLib  Version 2.10.4
PThreadPoolBase Class Reference

These classes and templates implement a generic thread pooling mechanism. More...

#include <threadpool.h>

Inheritance diagram for PThreadPoolBase:
PObject PThreadPool< Work_T > PQueuedThreadPool< Work_T >

List of all members.

Classes

class  InternalWorkBase
class  WorkerThreadBase

Public Member Functions

 ~PThreadPoolBase ()
virtual WorkerThreadBaseCreateWorkerThread ()=0
virtual WorkerThreadBaseAllocateWorker ()
virtual WorkerThreadBaseNewWorker ()
unsigned GetMaxWorkers () const
void SetMaxWorkers (unsigned count)
unsigned GetMaxUnits () const
void SetMaxUnits (unsigned count)

Protected Types

typedef std::vector
< WorkerThreadBase * > 
WorkerList_t

Protected Member Functions

 PThreadPoolBase (unsigned maxWorkerCount=10, unsigned maxWorkUnitCount=0)
virtual bool CheckWorker (WorkerThreadBase *worker)
void StopWorker (WorkerThreadBase *worker)

Protected Attributes

PMutex m_listMutex
WorkerList_t m_workers
unsigned m_maxWorkerCount
unsigned m_maxWorkUnitCount

Detailed Description

These classes and templates implement a generic thread pooling mechanism.

There are two forms, low level and high level. For high level, it is assumed that there is a pool of threads each with a queue of work items to be processed. TO use simply decare a class containing the void Work() function and create the poolwith PQueuedThreadPool. e.g.

class MyWork { void Work() { doIt(); } }

PQueuedThreadPool<MyWork> m_pool;

m_pool.AddWork(new MyWork());

To use low level, declare the following:

  • A class that describes a "unit" of work to be performed.
  • A class that described a worker thread within the pool. This class must be a descendant of PThreadPoolWorkerBase and must define the following member functions:

Constructor with one parameter declared as "PThreadPoolBase & threadPool" unsigned GetWorkSize() const; void OnAddWork(work_unit *); void OnRemoveWork(work_unit *);

void Shutdown(); void Main();

  • A class that describes the thread pool itself. This is defined using PThreadPool template

Example declarations:

struct MyWorkUnit { PString work; };

class MyWorkerThread : public PThreadPoolWorkerBase { public: MyWorkerThread(PThreadPoolBase & threadPool) : PThreadPoolWorkerBase(threadPool) { }

void Main(); void Shutdown(); unsigned GetWorkSize() const; void OnAddWork(MyWorkUnit * work); void OnRemoveWork(MyWorkUnit * work); };

class SIPMainThreadPool : public PThreadPool<MyWorkUnit, MyWorkerThread> { public: virtual PThreadPoolWorkerBase * CreateWorkerThread() { return new MyWorkerThread(*this); } };

The worker thread member functions operate as follows:

Constructor Called whenever a new worker thread is required

void Main() Called when the worker thread starts up

unsigned GetWorkSize() Called whenever the thread pool wants to know how "busy" the thread is. This is used when deciding how to allocate new work units

void OnAddWork(work_unit *) Called to add a new work unit to the thread

void OnRemoveWork(work_unit *); Called to remove a work unit from the thread

void Shutdown(); Called to close down the worker thread

The thread pool is used simply by instantiation as shown below.

MyThreadPool myThreadPool(10, 30);

If the second parameter is zero, the first paramater sets the maximum number of worker threads that will be created. If the second parameter is not zero, this is the maximum number of work units each thread can handle. The first parameter is then the "quanta" in which worker threads will be allocated

Once instantiated, the AddWork and RemoveWork member functions can be used to add and remove work units as required. The thread pool code will take care of starting, stopping and load balancing worker threads as required. Base class for thread pools.


Member Typedef Documentation

typedef std::vector<WorkerThreadBase *> PThreadPoolBase::WorkerList_t [protected]

Constructor & Destructor Documentation

PThreadPoolBase::PThreadPoolBase ( unsigned  maxWorkerCount = 10,
unsigned  maxWorkUnitCount = 0 
) [protected]

Member Function Documentation

virtual bool PThreadPoolBase::CheckWorker ( WorkerThreadBase worker) [protected, virtual]
unsigned PThreadPoolBase::GetMaxUnits ( ) const [inline]

References m_maxWorkUnitCount.

unsigned PThreadPoolBase::GetMaxWorkers ( ) const [inline]

References m_maxWorkerCount.

void PThreadPoolBase::SetMaxUnits ( unsigned  count) [inline]

References m_maxWorkUnitCount.

void PThreadPoolBase::SetMaxWorkers ( unsigned  count) [inline]

References m_maxWorkerCount.

void PThreadPoolBase::StopWorker ( WorkerThreadBase worker) [protected]

Member Data Documentation

unsigned PThreadPoolBase::m_maxWorkerCount [protected]

Referenced by GetMaxWorkers(), and SetMaxWorkers().

Referenced by GetMaxUnits(), and SetMaxUnits().


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