winsup/cygserver/threaded_queue.h

   1 /* threaded_queue.h
   2
   3    Copyright 2001, 2002, 2003 Red Hat Inc.
   4
   5    Written by Robert Collins <rbtcollins@hotmail.com>
   6
   7 This file is part of Cygwin.
   8
   9 This software is a copyrighted work licensed under the terms of the
  10 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
  11 details. */
  12
  13 #ifndef _THREADED_QUEUE_
  14 #define _THREADED_QUEUE_
  15
  16 /*****************************************************************************/
  17
  18 /* a specific request */
  19
  20 class queue_request
  21 {
  22 public:
  23   queue_request *_next;
  24
  25   queue_request () : _next (NULL) {}
  26   virtual ~queue_request ();
  27
  28   virtual void process () = 0;
  29 };
  30
  31 /*****************************************************************************/
  32
  33 /* a queue to allocate requests from n submission loops to x worker threads */
  34
  35 class queue_submission_loop;
  36
  37 class threaded_queue
  38 {
  39 public:
  40   threaded_queue (size_t initial_workers = 1);
  41   ~threaded_queue ();
  42
  43   void add_submission_loop (queue_submission_loop *);
  44
  45   bool running () const { return _running; }
  46
  47   bool start ();
  48   bool stop ();
  49
  50   void add (queue_request *);
  51
  52 private:
  53   long _workers_count;
  54   bool _running;
  55
  56   queue_submission_loop *_submitters_head;
  57
  58   long _requests_count;         // Informational only.
  59   queue_request *_requests_head;
  60
  61   CRITICAL_SECTION _queue_lock;
  62   HANDLE _requests_sem;         // == _requests_count
  63
  64   static DWORD WINAPI start_routine (LPVOID /* this */);
  65
  66   void create_workers (size_t initial_workers);
  67   void worker_loop ();
  68 };
  69
  70 /*****************************************************************************/
  71
  72 /* parameters for a request finding and submitting loop */
  73
  74 class queue_submission_loop
  75 {
  76   friend class threaded_queue;
  77
  78 public:
  79   queue_submission_loop (threaded_queue *, bool ninterruptible);
  80   virtual ~queue_submission_loop ();
  81
  82   bool start ();
  83   bool stop ();
  84
  85   threaded_queue *queue () { return _queue; };
  86
  87 protected:
  88   bool _running;
  89   HANDLE _interrupt_event;
  90   threaded_queue *const _queue;
  91
  92 private:
  93   bool _interruptible;
  94   HANDLE _hThread;
  95   DWORD _tid;
  96   queue_submission_loop *_next;
  97
  98   static DWORD WINAPI start_routine (LPVOID /* this */);
  99   virtual void request_loop () = 0;
 100 };
 101
 102 #ifdef __cplusplus
 103
 104 /*---------------------------------------------------------------------------*
 105  * Some type-safe versions of the various interlocked functions.
 106  *---------------------------------------------------------------------------*/
 107
 108 template <typename T> T *
 109 TInterlockedExchangePointer (T **lvalue, T *rvalue)
 110 {
 111   return reinterpret_cast<T *>
 112     (InterlockedExchangePointer (reinterpret_cast<void **> (lvalue),
 113                                  reinterpret_cast<void *> (rvalue)));
 114 }
 115
 116 template <typename T> T *
 117 TInterlockedCompareExchangePointer (T **lvalue, T *rvalue1, T *rvalue2)
 118 {
 119   return reinterpret_cast<T *>
 120     (InterlockedCompareExchangePointer (reinterpret_cast<void **> (lvalue),
 121                                         reinterpret_cast<void *> (rvalue1),
 122                                         reinterpret_cast<void *> (rvalue2)));
 123 }
 124
 125 #endif /* __cplusplus */
 126
 127 #endif /* _THREADED_QUEUE_ */