dep/src/zthread/Status.h

   1 /*
   2  * Copyright (c) 2005, Eric Crahen
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to deal
   6  * in the Software without restriction, including without limitation the rights
   7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8  * copies of the Software, and to permit persons to whom the Software is furnished
   9  * to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in all
  12  * copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  18  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  19  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  20  *
  21  */
  22
  23 #ifndef __ZTBLOCKINGSTATE_H__
  24 #define __ZTBLOCKINGSTATE_H__
  25
  26 #include <assert.h>
  27
  28 namespace ZThread {
  29
  30   /**
  31    * @class Status
  32    * @version 2.3.0
  33    *
  34    * A Status is associated with each Thread's Monitor. Monitors rely on a
  35    * Status object for providing information that will affect a blocking operations.
  36    */
  37   class Status {
  38   public:
  39     //! Aggregate of pending status changes
  40     volatile unsigned short _pending;
  41
  42     //! Interest mask
  43     volatile unsigned short _mask;
  44
  45   public:
  46
  47     //! State for the monitor
  48     typedef enum {
  49
  50       // Default
  51       INVALID      = 0x00,
  52
  53       // Valid states
  54       SIGNALED     = 0x01,
  55       INTERRUPTED  = 0x02,
  56       TIMEDOUT     = 0x04,
  57       CANCELED     = 0x08,
  58
  59       // Mask
  60       ANYTHING     = (~INVALID & ~CANCELED)
  61
  62     } STATE;
  63
  64     Status() : _pending((unsigned short)INVALID), _mask((unsigned short)ANYTHING) { }
  65
  66     /**
  67      * Set the mask for the STATE's that next() will report.
  68      * STATE's not covered by the interest mask can still be
  69      * set, they just aren't reported until the mask is changed
  70      * to cover that STATE.
  71      *
  72      * @param STATE
  73      * @pre accessed ONLY by the owning thread.
  74      */
  75     void interest(STATE mask) {
  76       _mask = static_cast<unsigned short>(mask);
  77     }
  78
  79     bool masked(STATE mask) {
  80       return (_mask & static_cast<unsigned short>(mask)) == 0;
  81     }
  82
  83     /**
  84      * Return true if next() will return a STATE covered
  85      * by the current interest mask and by the mask given
  86      * to this function.
  87      *
  88      * @param unsigned short
  89      * @pre accessed ONLY by the owning thread.
  90      */
  91     bool pending(unsigned short mask) {
  92
  93       assert(mask != INVALID);
  94       return ((_pending & _mask) & mask) != INVALID;
  95
  96     }
  97
  98     /**
  99      * Check the state without the interest mask.
 100      *
 101      * @param state
 102      * @return true if the flag is set
 103      * @pre access must be serial
 104      */
 105     bool examine(STATE state) {
 106       return (_pending & static_cast<unsigned short>(state)) != INVALID;
 107     }
 108
 109     /**
 110      * Add the flags to the current state.
 111      *
 112      * @param interest - the flags to add to the current state.
 113      * @pre access must be serial
 114      */
 115     void push(STATE interest) {
 116       _pending |= interest;
 117     }
 118
 119     /**
 120      * Clear the flags from the current state
 121      *
 122      * @param interest - the flags to clear from the current state.
 123      * @pre access must be serial
 124      */
 125     void clear(STATE interest) {
 126
 127       assert(interest != INVALID);
 128       assert(interest != ANYTHING);
 129       assert(interest != CANCELED);
 130
 131       _pending &= ~interest;
 132
 133     }
 134
 135     /**
 136      * Get the next state from set that has accumulated. The order STATES are
 137      * reported in is SIGNALED, TIMEOUT, or INTERRUPTED. Setting the
 138      * intrest mask allows certain state to be selectively ignored for
 139      * a time - but not lost. The states will become visible again as soon
 140      * as the interest mask is changed appropriately. The interest mask is
 141      * generally used to create uninterruptable waits (waiting for threads
 142      * to start, reacquiring a conditions predicate lock, etc)
 143      *
 144      * @return STATE
 145      * @pre access must be serial
 146      */
 147     STATE next() {
 148
 149       STATE state = INVALID;
 150
 151       if(((_pending & _mask) & SIGNALED) != 0) {
 152
 153         // Absorb the timeout if it happens when a signal
 154         // is available at the same time
 155         _pending &= ~(SIGNALED|TIMEDOUT);
 156         state = SIGNALED;
 157
 158       } else if(((_pending & _mask) & TIMEDOUT) != 0) {
 159
 160         _pending &= ~TIMEDOUT;
 161         state = TIMEDOUT;
 162
 163       } else if(((_pending & _mask) & INTERRUPTED) != 0) {
 164
 165         _pending &= ~INTERRUPTED;
 166         state = INTERRUPTED;
 167
 168       }
 169
 170       assert(state != INVALID);
 171       return state;
 172
 173     }
 174
 175   };
 176
 177 }; // namespace ZThread
 178
 179 #endif