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 24 do_bad_thing_with_location(unsigned index, char *char_ptr, char new_val) 25 { 26 unsigned what = new_val; 27 printf("new value written to array(%p) and index(%u) = %u\n", char_ptr, index, what); 28 char_ptr[index] = new_val; 29 } 30 31 uint32_t access_pool (uint32_t flag = 0); 32 33 uint32_t 34 access_pool (uint32_t flag) 35 { 36 static pthread_mutex_t g_access_mutex = PTHREAD_MUTEX_INITIALIZER; 37 static unsigned idx = 0; // Well-behaving thread only writes into indexs from 0..6. 38 if (flag == 0) 39 ::pthread_mutex_lock (&g_access_mutex); 40 41 // idx valid range is [0, 6]. 42 if (idx > 6) 43 idx = 0; 44 45 if (flag != 0) { 46 // Write into a forbidden area. 47 do_bad_thing_with_location(7, g_char_ptr, 99); 48 } 49 50 unsigned index = idx++; 51 52 if (flag == 0) 53 ::pthread_mutex_unlock (&g_access_mutex); 54 return g_char_ptr[index]; 55 } 56 57 void * 58 thread_func (void *arg) 59 { 60 uint32_t thread_index = *((uint32_t *)arg); 61 printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index); 62 63 uint32_t count = 0; 64 uint32_t val; 65 while (count++ < 15) 66 { 67 // random micro second sleep from zero to 3 seconds 68 int usec = ::rand() % 3000000; 69 printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec); 70 ::usleep (usec); 71 72 if (count < 7) 73 val = access_pool (); 74 else 75 val = access_pool (1); 76 77 printf ("%s (thread = %u) after usleep access_pool returns %d (count=%d)...\n", __FUNCTION__, thread_index, val, count); 78 } 79 printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index); 80 return NULL; 81 } 82 83 84 int main (int argc, char const *argv[]) 85 { 86 int err; 87 void *thread_result = NULL; 88 uint32_t thread_index_1 = 1; 89 uint32_t thread_index_2 = 2; 90 uint32_t thread_index_3 = 3; 91 92 g_char_ptr = (char *)malloc (10); 93 for (int i = 0; i < 10; ++i) 94 *g_char_ptr = 0; 95 96 // Create 3 threads 97 err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1); 98 err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2); 99 err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3); 100 101 struct { 102 int a; 103 int b; 104 int c; 105 } MyAggregateDataType; 106 107 printf ("Before turning all three threads loose...\n"); // Set break point at this line. 108 109 // Join all of our threads 110 err = ::pthread_join (g_thread_1, &thread_result); 111 err = ::pthread_join (g_thread_2, &thread_result); 112 err = ::pthread_join (g_thread_3, &thread_result); 113 114 return 0; 115 } 116
