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      1 //===-- main.cpp ------------------------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 // C includes
     11 #include <pthread.h>
     12 #include <stdio.h>
     13 #include <stdint.h>
     14 #include <stdlib.h>
     15 #include <unistd.h>
     16 
     17 pthread_t g_thread_1 = NULL;
     18 pthread_t g_thread_2 = NULL;
     19 pthread_t g_thread_3 = NULL;
     20 
     21 typedef enum {
     22     eGet,
     23     eAssign,
     24     eClearBits
     25 } MaskAction;
     26 
     27 uint32_t mask_access (MaskAction action, uint32_t mask = 0);
     28 
     29 uint32_t
     30 mask_access (MaskAction action, uint32_t mask)
     31 {
     32     static pthread_mutex_t g_mask_mutex = PTHREAD_MUTEX_INITIALIZER;
     33     static uint32_t g_mask = 0;
     34     ::pthread_mutex_lock (&g_mask_mutex);
     35     switch (action)
     36     {
     37     case eGet:
     38         break;
     39 
     40     case eAssign:
     41         g_mask |= mask;
     42         break;
     43 
     44     case eClearBits:
     45         g_mask &= ~mask;
     46         break;
     47     }
     48     uint32_t new_mask = g_mask;
     49     ::pthread_mutex_unlock (&g_mask_mutex);
     50     return new_mask;
     51 }
     52 
     53 void *
     54 thread_func (void *arg)
     55 {
     56     uint32_t thread_index = *((uint32_t *)arg);
     57     uint32_t thread_mask = (1u << (thread_index));
     58     printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index);
     59 
     60     while (mask_access(eGet) & thread_mask)
     61     {
     62         // random micro second sleep from zero to 3 seconds
     63         int usec = ::rand() % 3000000;
     64         printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec);
     65         ::usleep (usec);
     66         printf ("%s (thread = %u) after usleep ...\n", __FUNCTION__, thread_index); // Set break point at this line.
     67     }
     68     printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index);
     69     return NULL;
     70 }
     71 
     72 
     73 int main (int argc, char const *argv[])
     74 {
     75     int err;
     76     void *thread_result = NULL;
     77     uint32_t thread_index_1 = 1;
     78     uint32_t thread_index_2 = 2;
     79     uint32_t thread_index_3 = 3;
     80     uint32_t thread_mask_1 = (1u << thread_index_1);
     81     uint32_t thread_mask_2 = (1u << thread_index_2);
     82     uint32_t thread_mask_3 = (1u << thread_index_3);
     83 
     84     // Make a mask that will keep all threads alive
     85     mask_access (eAssign, thread_mask_1 | thread_mask_2 | thread_mask_3); // And that line.
     86 
     87     // Create 3 threads
     88     err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1);
     89     err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2);
     90     err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3);
     91 
     92     char line[64];
     93     while (mask_access(eGet) != 0)
     94     {
     95         printf ("Enter thread index to kill or ENTER for all:\n");
     96         fflush (stdout);
     97         // Kill threads by index, or ENTER for all threads
     98 
     99         if (fgets (line, sizeof(line), stdin))
    100         {
    101             if (line[0] == '\n' || line[0] == '\r' || line[0] == '\0')
    102             {
    103                 printf ("Exiting all threads...\n");
    104                 break;
    105             }
    106             int32_t index = strtoul (line, NULL, 0);
    107             switch (index)
    108             {
    109                 case 1: mask_access (eClearBits, thread_mask_1); break;
    110                 case 2: mask_access (eClearBits, thread_mask_2); break;
    111                 case 3: mask_access (eClearBits, thread_mask_3); break;
    112             }
    113             continue;
    114         }
    115 
    116         break;
    117     }
    118 
    119     // Clear all thread bits to they all exit
    120     mask_access (eClearBits, UINT32_MAX);
    121 
    122     // Join all of our threads
    123     err = ::pthread_join (g_thread_1, &thread_result);
    124     err = ::pthread_join (g_thread_2, &thread_result);
    125     err = ::pthread_join (g_thread_3, &thread_result);
    126 
    127     return 0;
    128 }
    129