| //===-- main.cpp ------------------------------------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // C includes |
| #include <pthread.h> |
| #include <stdio.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| |
| pthread_t g_thread_1 = NULL; |
| pthread_t g_thread_2 = NULL; |
| pthread_t g_thread_3 = NULL; |
| |
| char *g_char_ptr = NULL; |
| |
| void |
| do_bad_thing_with_location(unsigned index, char *char_ptr, char new_val) |
| { |
| unsigned what = new_val; |
| printf("new value written to array(%p) and index(%u) = %u\n", char_ptr, index, what); |
| char_ptr[index] = new_val; |
| } |
| |
| uint32_t access_pool (uint32_t flag = 0); |
| |
| uint32_t |
| access_pool (uint32_t flag) |
| { |
| static pthread_mutex_t g_access_mutex = PTHREAD_MUTEX_INITIALIZER; |
| static unsigned idx = 0; // Well-behaving thread only writes into indexs from 0..6. |
| if (flag == 0) |
| ::pthread_mutex_lock (&g_access_mutex); |
| |
| // idx valid range is [0, 6]. |
| if (idx > 6) |
| idx = 0; |
| |
| if (flag != 0) { |
| // Write into a forbidden area. |
| do_bad_thing_with_location(7, g_char_ptr, 99); |
| } |
| |
| unsigned index = idx++; |
| |
| if (flag == 0) |
| ::pthread_mutex_unlock (&g_access_mutex); |
| return g_char_ptr[index]; |
| } |
| |
| void * |
| thread_func (void *arg) |
| { |
| uint32_t thread_index = *((uint32_t *)arg); |
| printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index); |
| |
| uint32_t count = 0; |
| uint32_t val; |
| while (count++ < 15) |
| { |
| // random micro second sleep from zero to 3 seconds |
| int usec = ::rand() % 3000000; |
| printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec); |
| ::usleep (usec); |
| |
| if (count < 7) |
| val = access_pool (); |
| else |
| val = access_pool (1); |
| |
| printf ("%s (thread = %u) after usleep access_pool returns %d (count=%d)...\n", __FUNCTION__, thread_index, val, count); |
| } |
| printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index); |
| return NULL; |
| } |
| |
| |
| int main (int argc, char const *argv[]) |
| { |
| int err; |
| void *thread_result = NULL; |
| uint32_t thread_index_1 = 1; |
| uint32_t thread_index_2 = 2; |
| uint32_t thread_index_3 = 3; |
| |
| g_char_ptr = (char *)malloc (10); |
| for (int i = 0; i < 10; ++i) |
| *g_char_ptr = 0; |
| |
| // Create 3 threads |
| err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1); |
| err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2); |
| err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3); |
| |
| struct { |
| int a; |
| int b; |
| int c; |
| } MyAggregateDataType; |
| |
| printf ("Before turning all three threads loose...\n"); // Set break point at this line. |
| |
| // Join all of our threads |
| err = ::pthread_join (g_thread_1, &thread_result); |
| err = ::pthread_join (g_thread_2, &thread_result); |
| err = ::pthread_join (g_thread_3, &thread_result); |
| |
| return 0; |
| } |