VILLASnode/lib/queue_signalled.cpp

/* Wrapper around queue that uses POSIX CV's for signalling writes.
 *
 * Author: Georg Martin Reinke <georg.reinke@rwth-aachen.de>
 * SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
 * SPDX-License-Identifier: Apache-2.0
 */

#include <villas/node/config.hpp>
#include <villas/queue_signalled.h>

#ifdef HAS_EVENTFD
#include <sys/eventfd.h>
#endif

using namespace villas::node;

static void queue_signalled_cleanup(void *p) {
  struct CQueueSignalled *qs = (struct CQueueSignalled *)p;

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_unlock(&qs->pthread.mutex);
}

int villas::node::queue_signalled_init(struct CQueueSignalled *qs, size_t size,
                                       struct memory::Type *mem,
                                       enum QueueSignalledMode mode,
                                       int flags) {
  int ret;

  qs->mode = mode;

  if (qs->mode == QueueSignalledMode::AUTO) {
#ifdef __linux__
    if (flags & (int)QueueSignalledFlags::PROCESS_SHARED)
      qs->mode = QueueSignalledMode::PTHREAD;
    else {
#ifdef HAS_EVENTFD
      qs->mode = QueueSignalledMode::EVENTFD;
#else
      qs->mode = QueueSignalledMode::PTHREAD;
#endif
    }
#else
    qs->mode = QueueSignalledMode::PTHREAD;
#endif
  }

  ret = queue_init(&qs->queue, size, mem);
  if (ret < 0)
    return ret;

  if (qs->mode == QueueSignalledMode::PTHREAD) {
    pthread_condattr_t cvattr;
    pthread_mutexattr_t mtattr;

    ret = pthread_mutexattr_init(&mtattr);
    if (ret)
      return ret;

    ret = pthread_condattr_init(&cvattr);
    if (ret)
      return ret;

    if (flags & (int)QueueSignalledFlags::PROCESS_SHARED) {
      ret = pthread_mutexattr_setpshared(&mtattr, PTHREAD_PROCESS_SHARED);
      if (ret)
        return ret;

      ret = pthread_condattr_setpshared(&cvattr, PTHREAD_PROCESS_SHARED);
      if (ret)
        return ret;
    }

    ret = pthread_mutex_init(&qs->pthread.mutex, &mtattr);
    if (ret)
      return ret;

    ret = pthread_cond_init(&qs->pthread.ready, &cvattr);
    if (ret)
      return ret;

    ret = pthread_mutexattr_destroy(&mtattr);
    if (ret)
      return ret;

    ret = pthread_condattr_destroy(&cvattr);
    if (ret)
      return ret;
  } else if (qs->mode == QueueSignalledMode::POLLING) {
    /* Nothing todo */
  }
#ifdef HAS_EVENTFD
  else if (qs->mode == QueueSignalledMode::EVENTFD) {
    qs->eventfd = eventfd(0, 0);
    if (qs->eventfd < 0)
      return -2;
  }
#endif
  else
    return -1;

  return 0;
}

int villas::node::queue_signalled_destroy(struct CQueueSignalled *qs) {
  int ret;

  ret = queue_destroy(&qs->queue);
  if (ret < 0)
    return ret;

  if (qs->mode == QueueSignalledMode::PTHREAD) {
    pthread_cond_destroy(&qs->pthread.ready);
    pthread_mutex_destroy(&qs->pthread.mutex);
  } else if (qs->mode == QueueSignalledMode::POLLING) {
    // Nothing todo
  }
#ifdef HAS_EVENTFD
  else if (qs->mode == QueueSignalledMode::EVENTFD) {
    ret = close(qs->eventfd);
    if (ret)
      return ret;
  }
#endif
  else
    return -1;

  return 0;
}

int villas::node::queue_signalled_push(struct CQueueSignalled *qs, void *ptr) {
  int pushed;

  pushed = queue_push(&qs->queue, ptr);
  if (pushed <= 0)
    return pushed;

  if (qs->mode == QueueSignalledMode::PTHREAD) {
    pthread_mutex_lock(&qs->pthread.mutex);
    pthread_cond_broadcast(&qs->pthread.ready);
    pthread_mutex_unlock(&qs->pthread.mutex);
  } else if (qs->mode == QueueSignalledMode::POLLING) {
    // Nothing todo
  }
#ifdef HAS_EVENTFD
  else if (qs->mode == QueueSignalledMode::EVENTFD) {
    int ret;
    uint64_t incr = 1;
    ret = write(qs->eventfd, &incr, sizeof(incr));
    if (ret < 0)
      return ret;
  }
#endif
  else
    return -1;

  return pushed;
}

int villas::node::queue_signalled_push_many(struct CQueueSignalled *qs,
                                            void *ptr[], size_t cnt) {
  int pushed;

  pushed = queue_push_many(&qs->queue, ptr, cnt);
  if (pushed <= 0)
    return pushed;

  if (qs->mode == QueueSignalledMode::PTHREAD) {
    pthread_mutex_lock(&qs->pthread.mutex);
    pthread_cond_broadcast(&qs->pthread.ready);
    pthread_mutex_unlock(&qs->pthread.mutex);
  } else if (qs->mode == QueueSignalledMode::POLLING) {
    // Nothing todo
  }
#ifdef HAS_EVENTFD
  else if (qs->mode == QueueSignalledMode::EVENTFD) {
    int ret;
    uint64_t incr = 1;
    ret = write(qs->eventfd, &incr, sizeof(incr));
    if (ret < 0)
      return ret;
  }
#endif
  else
    return -1;

  return pushed;
}

int villas::node::queue_signalled_pull(struct CQueueSignalled *qs, void **ptr) {
  int pulled = 0;

  // Make sure that qs->mutex is unlocked if this thread gets cancelled
  pthread_cleanup_push(queue_signalled_cleanup, qs);

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_lock(&qs->pthread.mutex);

  while (!pulled) {
    pulled = queue_pull(&qs->queue, ptr);
    if (pulled < 0)
      break;
    else if (pulled == 0) {
      if (qs->mode == QueueSignalledMode::PTHREAD)
        pthread_cond_wait(&qs->pthread.ready, &qs->pthread.mutex);
      else if (qs->mode == QueueSignalledMode::POLLING)
        continue; // Try again
#ifdef HAS_EVENTFD
      else if (qs->mode == QueueSignalledMode::EVENTFD) {
        int ret;
        uint64_t cntr;
        ret = read(qs->eventfd, &cntr, sizeof(cntr));
        if (ret < 0)
          break;
      }
#endif
      else
        break;
    }
  }

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_unlock(&qs->pthread.mutex);

  pthread_cleanup_pop(0);

  return pulled;
}

int villas::node::queue_signalled_pull_many(struct CQueueSignalled *qs,
                                            void *ptr[], size_t cnt) {
  int pulled = 0;

  // Make sure that qs->mutex is unlocked if this thread gets cancelled
  pthread_cleanup_push(queue_signalled_cleanup, qs);

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_lock(&qs->pthread.mutex);

  while (!pulled) {
    pulled = queue_pull_many(&qs->queue, ptr, cnt);
    if (pulled < 0)
      break;
    else if (pulled == 0) {
      if (qs->mode == QueueSignalledMode::PTHREAD)
        pthread_cond_wait(&qs->pthread.ready, &qs->pthread.mutex);
      else if (qs->mode == QueueSignalledMode::POLLING)
        continue; // Try again
#ifdef HAS_EVENTFD
      else if (qs->mode == QueueSignalledMode::EVENTFD) {
        int ret;
        uint64_t cntr;
        ret = read(qs->eventfd, &cntr, sizeof(cntr));
        if (ret < 0)
          break;
      }
#endif
      else
        break;
    }
  }

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_unlock(&qs->pthread.mutex);

  pthread_cleanup_pop(0);

  return pulled;
}

int villas::node::queue_signalled_close(struct CQueueSignalled *qs) {
  int ret;

  if (qs->mode == QueueSignalledMode::PTHREAD)
    pthread_mutex_lock(&qs->pthread.mutex);

  ret = queue_close(&qs->queue);

  if (qs->mode == QueueSignalledMode::PTHREAD) {
    pthread_cond_broadcast(&qs->pthread.ready);
    pthread_mutex_unlock(&qs->pthread.mutex);
  } else if (qs->mode == QueueSignalledMode::POLLING) {
    // Nothing todo
  }
#ifdef HAS_EVENTFD
  else if (qs->mode == QueueSignalledMode::EVENTFD) {
    int ret;
    uint64_t incr = 1;

    ret = write(qs->eventfd, &incr, sizeof(incr));
    if (ret < 0)
      return ret;
  }
#endif
  else
    return -1;

  return ret;
}

int villas::node::queue_signalled_fd(struct CQueueSignalled *qs) {
  switch (qs->mode) {
#ifdef HAS_EVENTFD
  case QueueSignalledMode::EVENTFD:
    return qs->eventfd;
#endif
  default: {
  }
  }

  return -1;
}