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