🛠️🐜 Antkeeper superbuild with dependencies included
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285 lines
8.0 KiB
285 lines
8.0 KiB
/*
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Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely.
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*/
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/* Simple test of the SDL semaphore code */
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include "SDL.h"
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#define NUM_THREADS 10
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/* This value should be smaller than the maximum count of the */
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/* semaphore implementation: */
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#define NUM_OVERHEAD_OPS 10000
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#define NUM_OVERHEAD_OPS_MULT 10
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static SDL_sem *sem;
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int alive;
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typedef struct Thread_State
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{
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SDL_Thread *thread;
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int number;
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SDL_bool flag;
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int loop_count;
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int content_count;
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} Thread_State;
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static void
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killed(int sig)
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{
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alive = 0;
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}
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static int SDLCALL
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ThreadFuncRealWorld(void *data)
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{
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Thread_State *state = (Thread_State *)data;
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while (alive) {
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SDL_SemWait(sem);
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SDL_Log("Thread number %d has got the semaphore (value = %" SDL_PRIu32 ")!\n",
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state->number, SDL_SemValue(sem));
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SDL_Delay(200);
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SDL_SemPost(sem);
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SDL_Log("Thread number %d has released the semaphore (value = %" SDL_PRIu32 ")!\n",
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state->number, SDL_SemValue(sem));
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++state->loop_count;
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SDL_Delay(1); /* For the scheduler */
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}
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SDL_Log("Thread number %d exiting.\n", state->number);
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return 0;
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}
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static void
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TestRealWorld(int init_sem)
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{
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Thread_State thread_states[NUM_THREADS] = { { 0 } };
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int i;
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int loop_count;
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sem = SDL_CreateSemaphore(init_sem);
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SDL_Log("Running %d threads, semaphore value = %d\n", NUM_THREADS,
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init_sem);
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alive = 1;
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/* Create all the threads */
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for (i = 0; i < NUM_THREADS; ++i) {
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char name[64];
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(void)SDL_snprintf(name, sizeof(name), "Thread%u", (unsigned int)i);
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thread_states[i].number = i;
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thread_states[i].thread = SDL_CreateThread(ThreadFuncRealWorld, name, (void *)&thread_states[i]);
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}
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/* Wait 10 seconds */
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SDL_Delay(10 * 1000);
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/* Wait for all threads to finish */
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SDL_Log("Waiting for threads to finish\n");
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alive = 0;
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loop_count = 0;
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for (i = 0; i < NUM_THREADS; ++i) {
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SDL_WaitThread(thread_states[i].thread, NULL);
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loop_count += thread_states[i].loop_count;
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}
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SDL_Log("Finished waiting for threads, ran %d loops in total\n\n", loop_count);
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SDL_DestroySemaphore(sem);
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}
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static void
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TestWaitTimeout(void)
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{
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Uint32 start_ticks;
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Uint32 end_ticks;
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Uint32 duration;
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int retval;
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sem = SDL_CreateSemaphore(0);
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SDL_Log("Waiting 2 seconds on semaphore\n");
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start_ticks = SDL_GetTicks();
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retval = SDL_SemWaitTimeout(sem, 2000);
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end_ticks = SDL_GetTicks();
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duration = end_ticks - start_ticks;
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/* Accept a little offset in the effective wait */
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SDL_assert(duration > 1900 && duration < 2050);
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SDL_Log("Wait took %" SDL_PRIu32 " milliseconds\n\n", duration);
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/* Check to make sure the return value indicates timed out */
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if (retval != SDL_MUTEX_TIMEDOUT) {
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_SemWaitTimeout returned: %d; expected: %d\n\n", retval, SDL_MUTEX_TIMEDOUT);
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}
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SDL_DestroySemaphore(sem);
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}
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static void
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TestOverheadUncontended(void)
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{
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Uint32 start_ticks;
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Uint32 end_ticks;
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Uint32 duration;
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int i, j;
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sem = SDL_CreateSemaphore(0);
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SDL_Log("Doing %d uncontended Post/Wait operations on semaphore\n", NUM_OVERHEAD_OPS * NUM_OVERHEAD_OPS_MULT);
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start_ticks = SDL_GetTicks();
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for (i = 0; i < NUM_OVERHEAD_OPS_MULT; i++) {
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for (j = 0; j < NUM_OVERHEAD_OPS; j++) {
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SDL_SemPost(sem);
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}
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for (j = 0; j < NUM_OVERHEAD_OPS; j++) {
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SDL_SemWait(sem);
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}
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}
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end_ticks = SDL_GetTicks();
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duration = end_ticks - start_ticks;
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SDL_Log("Took %" SDL_PRIu32 " milliseconds\n\n", duration);
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SDL_DestroySemaphore(sem);
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}
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static int SDLCALL
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ThreadFuncOverheadContended(void *data)
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{
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Thread_State *state = (Thread_State *)data;
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if (state->flag) {
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while (alive) {
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if (SDL_SemTryWait(sem) == SDL_MUTEX_TIMEDOUT) {
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++state->content_count;
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}
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++state->loop_count;
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}
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} else {
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while (alive) {
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/* Timeout needed to allow check on alive flag */
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if (SDL_SemWaitTimeout(sem, 50) == SDL_MUTEX_TIMEDOUT) {
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++state->content_count;
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}
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++state->loop_count;
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}
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}
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return 0;
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}
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static void
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TestOverheadContended(SDL_bool try_wait)
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{
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Uint32 start_ticks;
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Uint32 end_ticks;
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Uint32 duration;
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Thread_State thread_states[NUM_THREADS] = { { 0 } };
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char textBuffer[1024];
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int loop_count;
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int content_count;
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int i, j;
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size_t len;
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sem = SDL_CreateSemaphore(0);
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SDL_Log("Doing %d contended %s operations on semaphore using %d threads\n",
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NUM_OVERHEAD_OPS * NUM_OVERHEAD_OPS_MULT, try_wait ? "Post/TryWait" : "Post/WaitTimeout", NUM_THREADS);
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alive = 1;
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/* Create multiple threads to starve the semaphore and cause contention */
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for (i = 0; i < NUM_THREADS; ++i) {
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char name[64];
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(void)SDL_snprintf(name, sizeof(name), "Thread%u", (unsigned int)i);
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thread_states[i].flag = try_wait;
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thread_states[i].thread = SDL_CreateThread(ThreadFuncOverheadContended, name, (void *)&thread_states[i]);
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}
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start_ticks = SDL_GetTicks();
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for (i = 0; i < NUM_OVERHEAD_OPS_MULT; i++) {
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for (j = 0; j < NUM_OVERHEAD_OPS; j++) {
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SDL_SemPost(sem);
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}
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/* Make sure threads consumed everything */
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while (SDL_SemValue(sem)) {
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/* Friendlier with cooperative threading models */
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SDL_Delay(1);
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}
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}
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end_ticks = SDL_GetTicks();
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alive = 0;
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loop_count = 0;
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content_count = 0;
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for (i = 0; i < NUM_THREADS; ++i) {
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SDL_WaitThread(thread_states[i].thread, NULL);
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loop_count += thread_states[i].loop_count;
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content_count += thread_states[i].content_count;
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}
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SDL_assert_release((loop_count - content_count) == NUM_OVERHEAD_OPS * NUM_OVERHEAD_OPS_MULT);
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duration = end_ticks - start_ticks;
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SDL_Log("Took %" SDL_PRIu32 " milliseconds, threads %s %d out of %d times in total (%.2f%%)\n",
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duration, try_wait ? "where contended" : "timed out", content_count,
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loop_count, ((float)content_count * 100) / loop_count);
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/* Print how many semaphores where consumed per thread */
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(void)SDL_snprintf(textBuffer, sizeof(textBuffer), "{ ");
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for (i = 0; i < NUM_THREADS; ++i) {
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if (i > 0) {
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len = SDL_strlen(textBuffer);
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(void)SDL_snprintf(textBuffer + len, sizeof(textBuffer) - len, ", ");
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}
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len = SDL_strlen(textBuffer);
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(void)SDL_snprintf(textBuffer + len, sizeof(textBuffer) - len, "%d", thread_states[i].loop_count - thread_states[i].content_count);
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}
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len = SDL_strlen(textBuffer);
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(void)SDL_snprintf(textBuffer + len, sizeof(textBuffer) - len, " }\n");
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SDL_Log("%s\n", textBuffer);
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SDL_DestroySemaphore(sem);
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}
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int main(int argc, char **argv)
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{
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int init_sem;
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/* Enable standard application logging */
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SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
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if (argc < 2) {
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SDL_Log("Usage: %s init_value\n", argv[0]);
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return 1;
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}
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/* Load the SDL library */
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if (SDL_Init(0) < 0) {
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
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return 1;
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}
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(void)signal(SIGTERM, killed);
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(void)signal(SIGINT, killed);
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init_sem = SDL_atoi(argv[1]);
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if (init_sem > 0) {
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TestRealWorld(init_sem);
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}
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TestWaitTimeout();
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TestOverheadUncontended();
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TestOverheadContended(SDL_FALSE);
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TestOverheadContended(SDL_TRUE);
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SDL_Quit();
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return 0;
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}
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