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 char *g_char_ptr = NULL;
22
23 void
do_bad_thing_with_location(char * char_ptr,char new_val)24 do_bad_thing_with_location(char *char_ptr, char new_val)
25 {
26 *char_ptr = new_val;
27 }
28
29 uint32_t access_pool (uint32_t flag = 0);
30
31 uint32_t
access_pool(uint32_t flag)32 access_pool (uint32_t flag)
33 {
34 static pthread_mutex_t g_access_mutex = PTHREAD_MUTEX_INITIALIZER;
35 if (flag == 0)
36 ::pthread_mutex_lock (&g_access_mutex);
37
38 char old_val = *g_char_ptr;
39 if (flag != 0)
40 do_bad_thing_with_location(g_char_ptr, old_val + 1);
41
42 if (flag == 0)
43 ::pthread_mutex_unlock (&g_access_mutex);
44 return *g_char_ptr;
45 }
46
47 void *
thread_func(void * arg)48 thread_func (void *arg)
49 {
50 uint32_t thread_index = *((uint32_t *)arg);
51 printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index);
52
53 uint32_t count = 0;
54 uint32_t val;
55 while (count++ < 15)
56 {
57 // random micro second sleep from zero to 3 seconds
58 int usec = ::rand() % 3000000;
59 printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec);
60 ::usleep (usec);
61
62 if (count < 7)
63 val = access_pool ();
64 else
65 val = access_pool (1);
66
67 printf ("%s (thread = %u) after usleep access_pool returns %d (count=%d)...\n", __FUNCTION__, thread_index, val, count);
68 }
69 printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index);
70 return NULL;
71 }
72
73
main(int argc,char const * argv[])74 int main (int argc, char const *argv[])
75 {
76 int err;
77 void *thread_result = NULL;
78 uint32_t thread_index_1 = 1;
79 uint32_t thread_index_2 = 2;
80 uint32_t thread_index_3 = 3;
81
82 g_char_ptr = (char *)malloc (1);
83 *g_char_ptr = 0;
84
85 // Create 3 threads
86 err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1);
87 err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2);
88 err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3);
89
90 printf ("Before turning all three threads loose...\n"); // Set break point at this line.
91
92 // Join all of our threads
93 err = ::pthread_join (g_thread_1, &thread_result);
94 err = ::pthread_join (g_thread_2, &thread_result);
95 err = ::pthread_join (g_thread_3, &thread_result);
96
97 return 0;
98 }
99