This file is indexed.

/usr/include/ptclib/threadpool.h is in libpt-dev 2.10.11~dfsg-1ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
/*
 * threadpool.h
 *
 * Generalised Thread Pooling functions
 *
 * Portable Tools Library
 *
 * Copyright (C) 2009 Post Increment
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Post Increment
 *
 * Portions of this code were written with the financial assistance of 
 * Metreos Corporation (http://www.metros.com).
 *
 * Contributor(s): ______________________________________.
 *
 * $Revision: 25362 $
 * $Author: rjongbloed $
 * $Date: 2011-03-20 18:27:31 -0500 (Sun, 20 Mar 2011) $
 */


#ifndef PTLIB_THREADPOOL_H
#define PTLIB_THREADPOOL_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#include <map>
#include <queue>


/**

   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.
  */
class PThreadPoolBase : public PObject
{
  public:
    class WorkerThreadBase : public PThread
    {
      public:
        WorkerThreadBase(Priority priority = NormalPriority)
          : PThread(100, NoAutoDeleteThread, priority, "Pool")
          , m_shutdown(false)
        { }

        virtual void Shutdown() = 0;
        virtual unsigned GetWorkSize() const = 0;

        bool   m_shutdown;
        PMutex m_workerMutex;
    };

    class InternalWorkBase
    {
      public:
        InternalWorkBase(const char * group)
        { 
          if (group != NULL)
            m_group = group;
        }
        std::string m_group;
    };

    ~PThreadPoolBase();

    virtual WorkerThreadBase * CreateWorkerThread() = 0;
    virtual WorkerThreadBase * AllocateWorker();
    virtual WorkerThreadBase * NewWorker();

    unsigned GetMaxWorkers() const { return m_maxWorkerCount; }

    void SetMaxWorkers(
      unsigned count
    ) { m_maxWorkerCount = count; }

    unsigned GetMaxUnits() const { return m_maxWorkUnitCount; }

    void SetMaxUnits(
      unsigned count
    ) { m_maxWorkUnitCount = count; }

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

    virtual bool CheckWorker(WorkerThreadBase * worker);
    void StopWorker(WorkerThreadBase * worker);
    PMutex m_listMutex;

    typedef std::vector<WorkerThreadBase *> WorkerList_t;
    WorkerList_t m_workers;

    unsigned m_maxWorkerCount;
    unsigned m_maxWorkUnitCount;
};


/** Low Level thread pool.
  */
template <class Work_T>
class PThreadPool : public PThreadPoolBase
{
  PCLASSINFO(PThreadPool, PThreadPoolBase);
  public:
    //
    //  constructor
    //
    PThreadPool(unsigned maxWorkers = 10, unsigned maxWorkUnits = 0)
      : PThreadPoolBase(maxWorkers, maxWorkUnits) 
    { }

    //
    // define the ancestor of the worker thread
    //
    class WorkerThread : public WorkerThreadBase
    {
      public:
        WorkerThread(PThreadPool & pool, Priority priority = NormalPriority)
          : WorkerThreadBase(priority)
          , m_pool(pool)
        {
        }

        virtual void AddWork(Work_T * work) = 0;
        virtual void RemoveWork(Work_T * work) = 0;
        virtual void Main() = 0;
  
      protected:
        PThreadPool & m_pool;
    };

    //
    // define internal worker wrapper class
    //
    class InternalWork : public InternalWorkBase
    {
      public:
        InternalWork(WorkerThread * worker, Work_T * work, const char * group)
          : InternalWorkBase(group)
          , m_worker(worker)
          , m_work(work)
        { 
        }

        WorkerThread * m_worker;
        Work_T * m_work;
    };

    //
    // define map for external work units to internal work
    //
    typedef std::map<Work_T *, InternalWork> ExternalToInternalWorkMap_T;
    ExternalToInternalWorkMap_T m_externalToInternalWorkMap;


    //
    // define class for storing group informationm
    //
    struct GroupInfo {
      unsigned m_count;
      WorkerThread * m_worker;
    };


    //
    //  define map for group ID to group information
    //
    typedef std::map<std::string, GroupInfo> GroupInfoMap_t;
    GroupInfoMap_t m_groupInfoMap;


    //
    //  add a new unit of work to a worker thread
    //
    bool AddWork(Work_T * work, const char * group = NULL)
    {
      PWaitAndSignal m(m_listMutex);

      // allocate by group if specified
      // else allocate to least busy
      WorkerThread * worker;
      if ((group == NULL) || (strlen(group) == 0)) {
        worker = (WorkerThread *)AllocateWorker();
      }
      else {

        // find the worker thread with the matching group ID
        // if no matching Id, then create a new thread
        typename GroupInfoMap_t::iterator g = m_groupInfoMap.find(group);
        if (g == m_groupInfoMap.end()) 
          worker = (WorkerThread *)AllocateWorker();
        else {
          worker = g->second.m_worker;
          PTRACE(4, "ThreadPool\tAllocated worker thread by group Id " << group);
        }
      }

      // if cannot allocate worker, return
      if (worker == NULL) 
        return false;

      // create internal work structure
      InternalWork internalWork(worker, work, group);

      // add work to external to internal map
      m_externalToInternalWorkMap.insert(typename ExternalToInternalWorkMap_T::value_type(work, internalWork));

      // add group ID to map
      if (!internalWork.m_group.empty()) {
        typename GroupInfoMap_t::iterator r = m_groupInfoMap.find(internalWork.m_group);
        if (r != m_groupInfoMap.end())
          ++r->second.m_count;
        else {
          GroupInfo info;
          info.m_count  = 1;
          info.m_worker = worker;
          m_groupInfoMap.insert(typename GroupInfoMap_t::value_type(internalWork.m_group, info));
        }
      }
      
      // give the work to the worker
      worker->AddWork(work);
    
      return true;
    }

    //
    //  remove a unit of work from a worker thread
    //
    bool RemoveWork(Work_T * work, bool removeFromWorker = true)
    {
      PWaitAndSignal m(m_listMutex);

      // find worker with work unit to remove
      typename ExternalToInternalWorkMap_T::iterator iterWork = m_externalToInternalWorkMap.find(work);
      if (iterWork == m_externalToInternalWorkMap.end())
        return false;

      InternalWork & internalWork = iterWork->second;

      // tell worker to stop processing work
      if (removeFromWorker)
        internalWork.m_worker->RemoveWork(work);

      // update group information
      if (!internalWork.m_group.empty()) {
        typename GroupInfoMap_t::iterator iterGroup = m_groupInfoMap.find(internalWork.m_group);
        PAssert(iterGroup != m_groupInfoMap.end(), "Attempt to find thread from unknown work group");
        if (iterGroup != m_groupInfoMap.end()) {
          if (--iterGroup->second.m_count == 0)
            m_groupInfoMap.erase(iterGroup);
        }
      }

      // see if workers need reorganising
      CheckWorker(internalWork.m_worker);

      // remove element from work unit map
      m_externalToInternalWorkMap.erase(iterWork);

      return true;
    }
};


/** High Level (queued work item) thread pool.
  */
template <class Work_T>
class PQueuedThreadPool : public PThreadPool<Work_T>
{
  public:
    //
    //  constructor
    //
    PQueuedThreadPool(unsigned maxWorkers = 10, unsigned maxWorkUnits = 0)
      : PThreadPool<Work_T>(maxWorkers, maxWorkUnits) 
    { }

    class QueuedWorkerThread : public PThreadPool<Work_T>::WorkerThread
    {
      public:
        QueuedWorkerThread(PThreadPool<Work_T> & pool, PThread::Priority priority = PThread::NormalPriority)
          : PThreadPool<Work_T>::WorkerThread(pool, priority)
          , m_available(0, INT_MAX)
        {
        }

        void AddWork(Work_T * work)
        {
          m_mutex.Wait();
          m_queue.push(work);
          m_available.Signal();
          m_mutex.Signal();
        }

        void RemoveWork(Work_T * )
        {
          m_mutex.Wait();
          Work_T * work = m_queue.front();
          m_queue.pop();
          m_mutex.Signal();
          delete work;
        }

        unsigned GetWorkSize() const
        {
          return (unsigned)m_queue.size();
        }

        void Main()
        {
          for (;;) {
            m_available.Wait();
            if (PThreadPool<Work_T>::WorkerThread::m_shutdown)
              break;

            m_mutex.Wait();
            Work_T * work = m_queue.empty() ? NULL : m_queue.front();
            m_mutex.Signal();

            if (work != NULL) {
              work->Work();
              PThreadPool<Work_T>::WorkerThread::m_pool.RemoveWork(work);
            }
          }
        }

        void Shutdown()
        {
          PThreadPool<Work_T>::WorkerThread::m_shutdown = true;
          m_available.Signal();
        }

      protected:
        typedef std::queue<Work_T *> Queue;
        Queue      m_queue;
        PMutex     m_mutex;
        PSemaphore m_available;
    };


    virtual PThreadPoolBase::WorkerThreadBase * CreateWorkerThread()
    { 
      return new QueuedWorkerThread(*this); 
    }
};


#endif // PTLIB_THREADPOOL_H


// End Of File ///////////////////////////////////////////////////////////////