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
17pthread_t g_thread_1 = NULL;
18pthread_t g_thread_2 = NULL;
19pthread_t g_thread_3 = NULL;
20
21uint32_t g_val = 0;
22
23uint32_t access_pool (uint32_t flag = 0);
24
25uint32_t
26access_pool (uint32_t flag)
27{
28    static pthread_mutex_t g_access_mutex = PTHREAD_MUTEX_INITIALIZER;
29    if (flag == 0)
30        ::pthread_mutex_lock (&g_access_mutex);
31
32    uint32_t old_val = g_val;
33    if (flag != 0) {
34        printf("changing g_val to %d...\n", (old_val + 1));
35        g_val = old_val + 1;
36    }
37
38    if (flag == 0)
39        ::pthread_mutex_unlock (&g_access_mutex);
40    return g_val;
41}
42
43void *
44thread_func (void *arg)
45{
46    uint32_t thread_index = *((uint32_t *)arg); // Break here in order to allow the thread
47                                                // to inherit the global watchpoint state.
48    printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index);
49
50    uint32_t count = 0;
51    uint32_t val;
52    while (count++ < 15)
53    {
54        // random micro second sleep from zero to 3 seconds
55        int usec = ::rand() % 3000000;
56        printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec);
57        ::usleep (usec);
58
59        if (count < 7)
60            val = access_pool ();
61        else
62            val = access_pool (1);
63
64        printf ("%s (thread = %u) after usleep access_pool returns %d (count=%d)...\n", __FUNCTION__, thread_index, val, count);
65    }
66    printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index);
67    return NULL;
68}
69
70
71int main (int argc, char const *argv[])
72{
73    int err;
74    void *thread_result = NULL;
75    uint32_t thread_index_1 = 1;
76    uint32_t thread_index_2 = 2;
77    uint32_t thread_index_3 = 3;
78
79    printf ("Before turning all three threads loose...\n"); // Set break point at this line,
80                                                            // in order to set our watchpoint.
81    // Create 3 threads
82    err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1);
83    err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2);
84    err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3);
85
86    // Join all of our threads
87    err = ::pthread_join (g_thread_1, &thread_result);
88    err = ::pthread_join (g_thread_2, &thread_result);
89    err = ::pthread_join (g_thread_3, &thread_result);
90
91    return 0;
92}
93