/*

 * Copyright (C) 2013 Martin Willi

 *

 * Copyright (C) secunet Security Networks AG

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the

 * Free Software Foundation; either version 2 of the License, or (at your

 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * for more details.

 */

#include <library.h>

#include <threading/thread.h>

#include <threading/mutex.h>

#include <threading/condvar.h>

#include <processing/jobs/callback_job.h>

#include "stream_service.h"

#include <errno.h>

#include <unistd.h>

#include <sys/stat.h>

typedef struct private_stream_service_t private_stream_service_t;

/**

 * Private data of an stream_service_t object.

 */

struct private_stream_service_t {

  /**

   * Public stream_service_t interface.

   */

  stream_service_t public;

  /**

   * Underlying socket

   */

  int fd;

  /**

   * Accept callback

   */

  stream_service_cb_t cb;

  /**

   * Accept callback data

   */

  void *data;

  /**

   * Job priority to invoke callback with

   */

  job_priority_t prio;

  /**

   * Maximum number of parallel callback invocations

   */

  u_int cncrncy;

  /**

   * Currently active jobs

   */

  u_int active;

  /**

   * Currently running jobs

   */

  u_int running;

  /**

   * mutex to lock active counter

   */

  mutex_t *mutex;

  /**

   * Condvar to wait for callback termination

   */

  condvar_t *condvar;

  /**

   * TRUE when the service is terminated

   */

  bool terminated;

  /**

   * Reference counter

   */

  refcount_t ref;

};

static void destroy_service(private_stream_service_t *this)

{

  if (ref_put(&this->ref))

  {

    close(this->fd);

    this->mutex->destroy(this->mutex);

    this->condvar->destroy(this->condvar);

    free(this);

  }

}

/**

 * Data to pass to async accept job

 */

typedef struct {

  /** callback function */

  stream_service_cb_t cb;

  /** callback data */

  void *data;

  /** accepted connection */

  int fd;

  /** reference to stream service */

  private_stream_service_t *this;

} async_data_t;

/**

 * Forward declaration

 */

static bool watch(private_stream_service_t *this, int fd, watcher_event_t event);

/**

 * Clean up accept data

 */

static void destroy_async_data(async_data_t *data)

{

  private_stream_service_t *this = data->this;

  this->mutex->lock(this->mutex);

  if (this->active-- == this->cncrncy && !this->terminated)

  {

    /* leaving concurrency limit, restart accept()ing. */

    lib->watcher->add(lib->watcher, this->fd,

              WATCHER_READ, (watcher_cb_t)watch, this);

  }

  this->condvar->signal(this->condvar);

  this->mutex->unlock(this->mutex);

  destroy_service(this);

  if (data->fd != -1)

  {

    close(data->fd);

  }

  free(data);

}

/**

 * Reduce running counter

 */

CALLBACK(reduce_running, void,

  async_data_t *data)

{

  private_stream_service_t *this = data->this;

  this->mutex->lock(this->mutex);

  this->running--;

  this->condvar->signal(this->condvar);

  this->mutex->unlock(this->mutex);

}

/**

 * Async processing of accepted connection

 */

static job_requeue_t accept_async(async_data_t *data)

{

  private_stream_service_t *this = data->this;

  stream_t *stream;

  this->mutex->lock(this->mutex);

  if (this->terminated)

  {

    this->mutex->unlock(this->mutex);

    return JOB_REQUEUE_NONE;

  }

  this->running++;

  this->mutex->unlock(this->mutex);

  stream = stream_create_from_fd(data->fd);

  if (stream)

  {

    /* FD is now owned by stream, don't close it during cleanup */

    data->fd = -1;

    thread_cleanup_push(reduce_running, data);

    thread_cleanup_push((void*)stream->destroy, stream);

    thread_cleanup_pop(!data->cb(data->data, stream));

    thread_cleanup_pop(TRUE);

  }

  return JOB_REQUEUE_NONE;

}

/**

 * Watcher callback function

 */

static bool watch(private_stream_service_t *this, int fd, watcher_event_t event)

{

  async_data_t *data;

  bool keep = TRUE;

  INIT(data,

    .cb = this->cb,

    .data = this->data,

    .fd = accept(fd, NULL, NULL),

    .this = this,

  );

  if (data->fd != -1 && !this->terminated)

  {

    this->mutex->lock(this->mutex);

    if (++this->active == this->cncrncy)

    {

      /* concurrency limit reached, stop accept()ing new connections */

      keep = FALSE;

    }

    this->mutex->unlock(this->mutex);

    ref_get(&this->ref);

    lib->processor->queue_job(lib->processor,

      (job_t*)callback_job_create_with_prio((void*)accept_async, data,

        (void*)destroy_async_data, (callback_job_cancel_t)return_false,

        this->prio));

  }

  else

  {

    free(data);

  }

  return keep;

}

METHOD(stream_service_t, on_accept, void,

  private_stream_service_t *this, stream_service_cb_t cb, void *data,

  job_priority_t prio, u_int cncrncy)

{

  this->mutex->lock(this->mutex);

  if (this->terminated)

  {

    this->mutex->unlock(this->mutex);

    return;

  }

  /* wait for all callbacks to return */

  while (this->active)

  {

    this->condvar->wait(this->condvar, this->mutex);

  }

  if (this->cb)

  {

    lib->watcher->remove(lib->watcher, this->fd);

  }

  this->cb = cb;

  this->data = data;

  if (prio <= JOB_PRIO_MAX)

  {

    this->prio = prio;

  }

  this->cncrncy = cncrncy;

  if (this->cb)

  {

    lib->watcher->add(lib->watcher, this->fd,

              WATCHER_READ, (watcher_cb_t)watch, this);

  }

  this->mutex->unlock(this->mutex);

}

METHOD(stream_service_t, destroy, void,

  private_stream_service_t *this)

{

  this->mutex->lock(this->mutex);

  lib->watcher->remove(lib->watcher, this->fd);

  this->terminated = TRUE;

  while (this->running)

  {

    this->condvar->wait(this->condvar, this->mutex);

  }

  this->mutex->unlock(this->mutex);

  destroy_service(this);

}

/**

 * See header

 */

stream_service_t *stream_service_create_from_fd(int fd)

{

  private_stream_service_t *this;

  INIT(this,

    .public = {

      .on_accept = _on_accept,

      .destroy = _destroy,

    },

    .fd = fd,

    .prio = JOB_PRIO_MEDIUM,

    .mutex = mutex_create(MUTEX_TYPE_RECURSIVE),

    .condvar = condvar_create(CONDVAR_TYPE_DEFAULT),

    .ref = 1,

  );

  return &this->public;

}