text: /***********************************************************************
   * cond.c
   *
   *   Copyright (C) 2007, 2008, 2013 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ***********************************************************************/
  
  #include <stdio.h>
  #include <pthread.h>
  #include <unistd.h>
  #include "ostest.h"
  
  #ifndef NULL
  # define NULL (void*)0
  #endif
  
  static volatile enum { RUNNING, MUTEX_WAIT, COND_WAIT} waiter_state;
  
  static pthread_mutex_t mutex;
  static pthread_cond_t  cond;
  static volatile int data_available = 0;
  static int waiter_nloops = 0;
  static int waiter_waits = 0;
  static int waiter_nerrors = 0;
  static int signaler_nloops = 0;
  static int signaler_already = 0;
  static int signaler_state = 0;
  static int signaler_nerrors = 0;
  
  static void *thread_waiter(void *parameter)
  {
    int status;
  
    printf("waiter_thread: Started\n");
  
    for(;;)
      {
        /* Take the mutex */
  
        waiter_state = MUTEX_WAIT;
        status       = pthread_mutex_lock(&mutex);
        waiter_state = RUNNING;
  
        if (status != 0)
          {
            printf("waiter_thread: ERROR pthread_mutex_lock failed, status=%d\n", status);
            waiter_nerrors++;
          }
  
        /* Check if data is available -- if data is not available then
         * wait for it
         */
  
        if (!data_available)
          {
             /* We are higher priority than the signaler thread so the
              * only time that the signaler thread will have a chance to run is when
              * we are waiting for the condition variable.  In this case, pthread_cond_wait
              * will automatically release the mutex for the signaler (then re-acquire
              * the mutex before returning.
              */
  
             waiter_state = COND_WAIT;
             status       = pthread_cond_wait(&cond, &mutex);
             waiter_state = RUNNING;
  
             if (status != 0)
               {
                 printf("waiter_thread: ERROR pthread_cond_wait failed, status=%d\n", status);
                 waiter_nerrors++;
               }
  
             waiter_waits++;
          }
  
        /* Now data should be available */
  
        if (!data_available)
          {
            printf("waiter_thread: ERROR data not available after wait\n");
            waiter_nerrors++;
          }
  
        /* Clear data available */
  
        data_available = 0;
  
        /* Release the mutex */
  
        status = pthread_mutex_unlock(&mutex);
        if (status != 0)
          {
            printf("waiter_thread: ERROR waiter: pthread_mutex_unlock failed, status=%d\n", status);
            waiter_nerrors++;
          }
  
        waiter_nloops++;
      }
  
    return NULL;
  }
  
  static void *thread_signaler(void *parameter)
  {
    int status;
    int i;
  
    printf("thread_signaler: Started\n");
    for (i = 0; i < 32; i++)
      {
        /* Take the mutex.  The waiter is higher priority and should
         * run until it waits for the condition.  So, at this point
         * signaler should be waiting for the condition.
         */
  
        status = pthread_mutex_lock(&mutex);
        if (status != 0)
          {
            printf("thread_signaler: ERROR pthread_mutex_lock failed, status=%d\n", status);
            signaler_nerrors++;
          }
  
        /* Verify the state */
  
        if (waiter_state != COND_WAIT)
          {
            printf("thread_signaler: ERROR waiter state = %d != COND_WAITING\n", waiter_state);
            signaler_state++;
          }
  
        if (data_available)
          {
            printf("thread_signaler: ERROR data already available, waiter_state=%d\n", waiter_state);
            signaler_already++;
          }
  
        /* Set data available and signal the waiter */
  
        data_available = 1;
        status = pthread_cond_signal(&cond);
        if (status != 0)
          {
            printf("thread_signaler: ERROR pthread_cond_signal failed, status=%d\n", status);
            signaler_nerrors++;
          }
  
       /* Release the mutex */
  
        status = pthread_mutex_unlock(&mutex);
        if (status != 0)
          {
            printf("thread_signaler: ERROR pthread_mutex_unlock failed, status=%d\n", status);
            signaler_nerrors++;
          }
  
        signaler_nloops++;
      }
  
    printf("thread_signaler: Terminating\n");
    pthread_exit(NULL);
    return NULL; /* Non-reachable -- needed for some compilers */
  }
  
  void cond_test(void)
  {
    pthread_t waiter;
    pthread_t signaler;
    pthread_attr_t attr;
  #ifdef SDCC
    pthread_addr_t result;
  #endif
    struct sched_param sparam;
    int prio_min;
    int prio_max;
    int prio_mid;
    int status;
  
    /* Initialize the mutex */
  
    printf("cond_test: Initializing mutex\n");
    status = pthread_mutex_init(&mutex, NULL);
    if (status != 0)
      {
        printf("cond_test: ERROR pthread_mutex_init failed, status=%d\n", status);
      }
  
    /* Initialize the condition variable */
  
    printf("cond_test: Initializing cond\n");
    status = pthread_cond_init(&cond, NULL);
    if (status != 0)
      {
        printf("cond_test: ERROR pthread_condinit failed, status=%d\n", status);
      }
  
    /* Start the waiter thread at higher priority */
  
    printf("cond_test: Starting waiter\n");
    status = pthread_attr_init(&attr);
    if (status != 0)
      {
        printf("cond_test: pthread_attr_init failed, status=%d\n", status);
      }
  
    prio_min = sched_get_priority_min(SCHED_FIFO);
    prio_max = sched_get_priority_max(SCHED_FIFO);
    prio_mid = (prio_min + prio_max) / 2;
  
    sparam.sched_priority = prio_mid;
    status = pthread_attr_setschedparam(&attr,&sparam);
    if (status != OK)
      {
        printf("cond_test: pthread_attr_setschedparam failed, status=%d\n", status);
      }
    else
      {
        printf("cond_test: Set thread 1 priority to %d\n", sparam.sched_priority);
      }
  
    status = pthread_create(&waiter, &attr, thread_waiter, NULL);
    if (status != 0)
      {
        printf("cond_test: pthread_create failed, status=%d\n", status);
      }
  
    printf("cond_test: Starting signaler\n");
    status = pthread_attr_init(&attr);
    if (status != 0)
      {
        printf("cond_test: pthread_attr_init failed, status=%d\n", status);
      }
  
    sparam.sched_priority = (prio_min + prio_mid) / 2;
    status = pthread_attr_setschedparam(&attr,&sparam);
    if (status != OK)
      {
        printf("cond_test: pthread_attr_setschedparam failed, status=%d\n", status);
      }
    else
      {
        printf("cond_test: Set thread 2 priority to %d\n", sparam.sched_priority);
      }
  
    status = pthread_create(&signaler, &attr, thread_signaler, NULL);
    if (status != 0)
      {
        printf("cond_test: pthread_create failed, status=%d\n", status);
      }
  
    /* Wait for the threads to stop */
  
  #ifdef SDCC
    pthread_join(signaler, &result);
  #else
    pthread_join(signaler, NULL);
  #endif
    printf("cond_test: signaler terminated, now cancel the waiter\n");
    pthread_detach(waiter);
    pthread_cancel(waiter);
  
    printf("cond_test: \tWaiter\tSignaler\n");
    printf("cond_test: Loops\t%d\t%d\n", waiter_nloops, signaler_nloops);
    printf("cond_test: Errors\t%d\t%d\n", waiter_nerrors, signaler_nerrors);
    printf("cond_test:\n");
    printf("cond_test: %d times, waiter did not have to wait for data\n",
            waiter_nloops - waiter_waits);
    printf("cond_test: %d times, data was already available when the signaler run\n",
            signaler_already);
    printf("cond_test: %d times, the waiter was in an unexpected state when the signaler ran\n",
           signaler_state);
  }
  