src/WINNT/client_osi/trylock.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 /* Copyright (C) 1994 Cazamar Systems, Inc. */
  11
  12 #include <afs/param.h>
  13 #include <afs/stds.h>
  14
  15 #include "windows.h"
  16 #include <string.h>
  17 #include "main.h"
  18 #include "trylock.h"
  19 #include "osi.h"
  20 #include <assert.h>
  21
  22 #define main_NITERS     10000   /* bops between the two */
  23
  24 osi_rwlock_t trylock_first;
  25 osi_mutex_t trylock_second;
  26 osi_rwlock_t trylock_third;
  27
  28 /* counters are not shared */
  29 static long neonCount;
  30 static long salmonCount;
  31 static long interestingEvents;
  32
  33 /* set under trylock_first rwlock */
  34 static int done;
  35
  36 /* neon tetras swim normally, i.e. downstream down the locking hierarchy */
  37 long main_Neon(long parm)
  38 {
  39         while (1) {
  40                 Sleep(0);
  41                 lock_ObtainRead(&trylock_first);
  42                 Sleep(0);
  43                 lock_ObtainMutex(&trylock_second);
  44                 Sleep(0);
  45                 lock_ObtainWrite(&trylock_third);
  46                 Sleep(0);
  47                 lock_ReleaseWrite(&trylock_third);
  48                 lock_ReleaseMutex(&trylock_second);
  49                 lock_ReleaseRead(&trylock_first);
  50
  51                 if (neonCount++ >= main_NITERS) break;
  52         }
  53
  54         /* bump done counter under lock */
  55         lock_ObtainMutex(&trylock_second);
  56         done++;
  57         lock_ReleaseMutex(&trylock_second);
  58
  59         return 0;
  60 }
  61
  62 /* go upstream against the locking hierarchy */
  63 long main_Salmon(long parm)
  64 {
  65         long code;
  66         while (1) {
  67                 code = lock_TryRead(&trylock_third);
  68                 if (code == 0) {
  69                         /* failed, release others, wait for this, and continue */
  70                         lock_ObtainRead(&trylock_third);
  71                         lock_ReleaseRead(&trylock_third);
  72                         interestingEvents++;
  73                         continue;
  74                 }
  75                 code = lock_TryMutex(&trylock_second);
  76                 if (!code) {
  77                         /* failed */
  78                         lock_ReleaseRead(&trylock_third);
  79                         lock_ObtainMutex(&trylock_second);
  80                         lock_ReleaseMutex(&trylock_second);
  81                         interestingEvents++;
  82                         continue;
  83                 }
  84                 code = lock_TryWrite(&trylock_first);
  85                 if (!code) {
  86                         lock_ReleaseRead(&trylock_third);
  87                         lock_ReleaseMutex(&trylock_second);
  88                         lock_ObtainWrite(&trylock_first);
  89                         lock_ReleaseWrite(&trylock_first);
  90                         interestingEvents++;
  91                         continue;
  92                 }
  93                 /* done */
  94                 lock_ReleaseRead(&trylock_third);
  95                 lock_ReleaseMutex(&trylock_second);
  96                 lock_ReleaseWrite(&trylock_first);
  97
  98                 /* check for done */
  99                 if (salmonCount++ >= main_NITERS) break;
 100
 101                 Sleep(0);
 102         }
 103
 104         lock_ObtainMutex(&trylock_second);
 105         done++;
 106         lock_ReleaseMutex(&trylock_second);
 107         return 0;
 108 }
 109
 110 main_TryLockTest(HANDLE hWnd)
 111 {
 112         long mod1ID;
 113         long mod2ID;
 114         HANDLE mod1Handle;
 115         HANDLE mod2Handle;
 116         long localDone;
 117
 118         osi_Init();
 119
 120         salmonCount = 0;
 121         neonCount = 0;
 122         interestingEvents = 0;
 123
 124         /* create three processes, two modifiers and one scanner.  The scanner
 125          * checks that the basic invariants are being maintained, while the
 126          * modifiers modify the global variables, maintaining certain invariants
 127          * by using locks.
 128          */
 129         done = 0;
 130
 131         main_ForceDisplay(hWnd);
 132
 133         lock_InitializeRWLock(&trylock_first, "first lock");
 134         lock_InitializeRWLock(&trylock_third, "third lock");
 135         lock_InitializeMutex(&trylock_second, "second mutex");
 136
 137         mod1Handle = CreateThread((SECURITY_ATTRIBUTES *) 0, 0,
 138                 (LPTHREAD_START_ROUTINE) main_Neon, 0, 0, &mod1ID);
 139         if (mod1Handle == NULL) return -1;
 140
 141         mod2Handle = CreateThread((SECURITY_ATTRIBUTES *) 0, 0,
 142                 (LPTHREAD_START_ROUTINE) main_Salmon, 0, 0, &mod2ID);
 143         if (mod2Handle == NULL) return -2;
 144
 145         /* start running check daemon */
 146         while (1) {
 147                 Sleep(1000);
 148                 wsprintf(main_screenText[1], "Neon tetra iteration %d", neonCount);
 149                 wsprintf(main_screenText[2], "Salmon iteration %d", salmonCount);
 150                 wsprintf(main_screenText[3], "Interesting events: %d", interestingEvents);
 151                 main_ForceDisplay(hWnd);
 152
 153                 /* copy out count of # of dudes finished */
 154                 lock_ObtainMutex(&trylock_second);
 155                 localDone = done;
 156                 lock_ReleaseMutex(&trylock_second);
 157
 158                 /* right now, we're waiting for 2 threads */
 159                 if (localDone == 2) break;
 160         }
 161
 162         /* done, release and finalize all locks */
 163         lock_FinalizeRWLock(&trylock_first);
 164         lock_FinalizeRWLock(&trylock_third);
 165         lock_FinalizeMutex(&trylock_second);
 166
 167         /* finally clean up thread handles */
 168         CloseHandle(mod1Handle);
 169         CloseHandle(mod2Handle);
 170         return 0;
 171 }