winsup/cygserver/threaded_queue.h

   1 /* threaded_queue.h
   2
   3    Written by Robert Collins <rbtcollins@hotmail.com>
   4
   5 This file is part of Cygwin.
   6
   7 This software is a copyrighted work licensed under the terms of the
   8 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
   9 details. */
  10
  11 #ifndef _THREADED_QUEUE_
  12 #define _THREADED_QUEUE_
  13
  14 /*****************************************************************************/
  15
  16 /* a specific request */
  17
  18 class queue_request
  19 {
  20 public:
  21   queue_request *_next;
  22
  23   queue_request () : _next (NULL) {}
  24   virtual ~queue_request ();
  25
  26   virtual void process () = 0;
  27 };
  28
  29 /*****************************************************************************/
  30
  31 /* a queue to allocate requests from n submission loops to x worker threads */
  32
  33 class queue_submission_loop;
  34
  35 class threaded_queue
  36 {
  37 public:
  38   threaded_queue (size_t initial_workers = 1);
  39   ~threaded_queue ();
  40
  41   void add_submission_loop (queue_submission_loop *);
  42
  43   bool running () const { return _running; }
  44
  45   bool start ();
  46   bool stop ();
  47
  48   void add (queue_request *);
  49
  50 private:
  51   LONG _workers_count;
  52   LONG _workers_busy;
  53   bool _running;
  54
  55   queue_submission_loop *_submitters_head;
  56
  57   long _requests_count;         // Informational only.
  58   queue_request *_requests_head;
  59
  60   CRITICAL_SECTION _queue_lock;
  61   HANDLE _requests_sem;         // == _requests_count
  62
  63   static DWORD WINAPI start_routine (LPVOID /* this */);
  64
  65   void create_workers (size_t initial_workers);
  66   void worker_loop ();
  67 };
  68
  69 /*****************************************************************************/
  70
  71 /* parameters for a request finding and submitting loop */
  72
  73 class queue_submission_loop
  74 {
  75   friend class threaded_queue;
  76
  77 public:
  78   queue_submission_loop (threaded_queue *, bool ninterruptible);
  79   virtual ~queue_submission_loop ();
  80
  81   bool start ();
  82   bool stop ();
  83
  84   threaded_queue *queue () { return _queue; };
  85
  86 protected:
  87   bool _running;
  88   HANDLE _interrupt_event;
  89   threaded_queue *const _queue;
  90
  91 private:
  92   bool _interruptible;
  93   HANDLE _hThread;
  94   DWORD _tid;
  95   queue_submission_loop *_next;
  96
  97   static DWORD WINAPI start_routine (LPVOID /* this */);
  98   virtual void request_loop () = 0;
  99 };
 100
 101 #ifdef __cplusplus
 102
 103 /*---------------------------------------------------------------------------*
 104  * Some type-safe versions of the various interlocked functions.
 105  *---------------------------------------------------------------------------*/
 106
 107 template <typename T> T *
 108 TInterlockedExchangePointer (T **lvalue, T *rvalue)
 109 {
 110   return reinterpret_cast<T *>
 111     (InterlockedExchangePointer (reinterpret_cast<void **> (lvalue),
 112                                  reinterpret_cast<void *> (rvalue)));
 113 }
 114
 115 template <typename T> T *
 116 TInterlockedCompareExchangePointer (T **lvalue, T *rvalue1, T *rvalue2)
 117 {
 118   return reinterpret_cast<T *>
 119     (InterlockedCompareExchangePointer (reinterpret_cast<void **> (lvalue),
 120                                         reinterpret_cast<void *> (rvalue1),
 121                                         reinterpret_cast<void *> (rvalue2)));
 122 }
 123
 124 #endif /* __cplusplus */
 125
 126 #endif /* _THREADED_QUEUE_ */