/** * apr tutorial sample code * http://dev.ariel-networks.com/apr/ */#ifdef HAVE_CONFIG_H#include <config.h>#endif#include <stdio.h>#include <stdlib.h>#include <assert.h>#include <apr_general.h>#include <apr_thread_proc.h>#include <apr_thread_cond.h>/** * Shared context between main-thread and sub-thread. * In this sample, main-thread wakes sub-thread up. */typedef struct {    /* condition variable should be used with a mutex variable */    apr_thread_mutex_t *mutex;    apr_thread_cond_t  *cond;    /* shared context depends on application */    int input_num;} my_production_t;static void* APR_THREAD_FUNC do_consume(apr_thread_t *thd, void *data);/** * @return TRUE when we wake the consumer up, othewrise FALSE. */static int do_produce(my_production_t *prod){    int c;    puts("type any key and return-key to wake consumer-thread up");    c = getchar();    if (c > 0) {        apr_thread_mutex_lock(prod->mutex);        prod->input_num = c;        puts("to wake consumer-thread up");        apr_thread_cond_signal(prod->cond);        apr_thread_mutex_unlock(prod->mutex);        return TRUE;    } else {        return FALSE;    }}/** * Thread execution and condition variable sample code * @remark Error checks omitted */int main(int argc, const char *argv[]){    apr_status_t rv;    apr_pool_t *mp;    apr_thread_t *thd;    my_production_t prod = { NULL, NULL, -1 };            apr_initialize();    apr_pool_create(&mp, NULL);    apr_thread_mutex_create(&prod.mutex, APR_THREAD_MUTEX_UNNESTED, mp);    apr_thread_cond_create(&prod.cond, mp);        apr_thread_create(&thd, NULL, do_consume, &prod, mp);    /* if it returns FALSE, the consumer thread still sleeps */    do_produce(&prod);    apr_thread_join(&rv, thd);    apr_terminate();    return 0;}/** * Thread entry point * This thread sleeps until the other thread wakes up by my_production_t::cond. */static void* APR_THREAD_FUNC do_consume(apr_thread_t *thd, void *data){    my_production_t *prod = data;    puts("consumer thread is sleeping(blocking)...");    apr_thread_mutex_lock(prod->mutex);    while (prod->input_num == -1) {        apr_thread_cond_wait(prod->cond, prod->mutex);    }    apr_thread_mutex_unlock(prod->mutex);    printf("consumer thread is waken, getting the input %d\n", prod->input_num);    apr_thread_exit(thd, APR_SUCCESS);    return NULL;}