/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * SPDX-License-Identifier: MPL-2.0

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, you can obtain one at https://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

#include <stdlib.h>

#include <sys/types.h>

#include <unistd.h>

#include <isc/async.h>

#include <isc/atomic.h>

#include <isc/barrier.h>

#include <isc/job.h>

#include <isc/loop.h>

#include <isc/magic.h>

#include <isc/mem.h>

#include <isc/mutex.h>

#include <isc/refcount.h>

#include <isc/result.h>

#include <isc/signal.h>

#include <isc/strerr.h>

#include <isc/thread.h>

#include <isc/util.h>

#include <isc/uv.h>

#include <isc/work.h>

#include "async_p.h"

#include "job_p.h"

#include "loop_p.h"

void

isc_async_run(isc_loop_t *loop, isc_job_cb cb, void *cbarg) {

  REQUIRE(VALID_LOOP(loop));

  REQUIRE(cb != NULL);

  isc_job_t *job = isc_mem_get(loop->mctx, sizeof(*job));

  *job = (isc_job_t){

    .cb = cb,

    .cbarg = cbarg,

  };

  cds_wfcq_node_init(&job->wfcq_node);

  /*

   * cds_wfcq_enqueue() is non-blocking and enqueues the job to async

   * queue.

   *

   * The function returns 'false' in case the queue was empty - in such

   * case we need to trigger the async callback.

   */

  if (!cds_wfcq_enqueue(&loop->async_jobs.head, &loop->async_jobs.tail,

            &job->wfcq_node))

  {

    int r = uv_async_send(&loop->async_trigger);

    UV_RUNTIME_CHECK(uv_async_send, r);

  }

}

void

isc__async_cb(uv_async_t *handle) {

  isc_loop_t *loop = uv_handle_get_data(handle);

  isc_jobqueue_t jobs;

  REQUIRE(VALID_LOOP(loop));

  /* Initialize local wfcqueue */

  __cds_wfcq_init(&jobs.head, &jobs.tail);

  /*

   * Move all the elements from loop->async_jobs to a local jobs queue.

   *

   * __cds_wfcq_splice_blocking() assumes that synchronization is

   * done externally - there's no internal locking, unlike

   * cds_wfcq_splice_blocking(), and we do not need to check whether

   * it needs to block, unlike __cds_wfcq_splice_nonblocking().

   *

   * The reason we can use __cds_wfcq_splice_blocking() is that the

   * only other function we use is cds_wfcq_enqueue() which doesn't

   * require any synchronization (see the table in urcu/wfcqueue.h

   * for more details).

   */

  enum cds_wfcq_ret ret = __cds_wfcq_splice_blocking(

    &jobs.head, &jobs.tail, &loop->async_jobs.head,

    &loop->async_jobs.tail);

  INSIST(ret != CDS_WFCQ_RET_WOULDBLOCK);

  if (ret == CDS_WFCQ_RET_SRC_EMPTY) {

    /*

     * Nothing to do, the source queue was empty - most

     * probably we were called from isc__async_close() below.

     */

    return;

  }

  /*

   * Walk through the local queue which has now all the members copied

   * locally, and call the callbacks and free all the isc_job_t(s).

   */

  struct cds_wfcq_node *node, *next;

  __cds_wfcq_for_each_blocking_safe(&jobs.head, &jobs.tail, node, next) {

    isc_job_t *job = caa_container_of(node, isc_job_t, wfcq_node);

    job->cb(job->cbarg);

    isc_mem_put(loop->mctx, job, sizeof(*job));

  }

}

void

isc__async_close(uv_handle_t *handle) {

  isc_loop_t *loop = uv_handle_get_data(handle);

  isc__async_cb(&loop->async_trigger);

}