/*

   Unix SMB/CIFS implementation.

   Infrastructure for async requests

   Copyright (C) Volker Lendecke 2008

   Copyright (C) Stefan Metzmacher 2009

     ** NOTE! The following LGPL license applies to the tevent

     ** library. This does NOT imply that all of Samba is released

     ** under the LGPL

   This library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 3 of the License, or (at your option) any later version.

   This library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with this library; if not, see <http://www.gnu.org/licenses/>.

*/

#include "replace.h"

#include "tevent.h"

#include "tevent_internal.h"

#include "tevent_util.h"

#undef tevent_queue_add

#undef tevent_queue_add_entry

#undef tevent_queue_add_optimize_empty

struct tevent_queue_entry {

  struct tevent_queue_entry *prev, *next;

  struct tevent_queue *queue;

  bool triggered;

  struct tevent_req *req;

  struct tevent_context *ev;

  tevent_queue_trigger_fn_t trigger;

  const char *trigger_name;

  void *private_data;

  uint64_t tag;

};

struct tevent_queue {

  const char *name;

  const char *location;

  bool running;

  struct tevent_immediate *immediate;

  size_t length;

  struct tevent_queue_entry *list;

};

static void tevent_queue_immediate_trigger(struct tevent_context *ev,

             struct tevent_immediate *im,

             void *private_data);

static int tevent_queue_entry_destructor(struct tevent_queue_entry *e)

{

  struct tevent_queue *q = e->queue;

  if (!q) {

    return 0;

  }

  tevent_trace_queue_callback(q->list->ev, e, TEVENT_EVENT_TRACE_DETACH);

  tevent_thread_call_depth_notify(TEVENT_CALL_FLOW_REQ_QUEUE_LEAVE,

          q->list->req,

          q->list->req->internal.call_depth,

          e->trigger_name);

  DLIST_REMOVE(q->list, e);

  q->length--;

  if (!q->running) {

    return 0;

  }

  if (!q->list) {

    return 0;

  }

  if (q->list->triggered) {

    return 0;

  }

  tevent_schedule_immediate(q->immediate,

          q->list->ev,

          tevent_queue_immediate_trigger,

          q);

  return 0;

}

static int tevent_queue_destructor(struct tevent_queue *q)

{

  q->running = false;

  while (q->list) {

    struct tevent_queue_entry *e = q->list;

    talloc_free(e);

  }

  return 0;

}

struct tevent_queue *_tevent_queue_create(TALLOC_CTX *mem_ctx,

            const char *name,

            const char *location)

{

  struct tevent_queue *queue;

  queue = talloc_zero(mem_ctx, struct tevent_queue);

  if (!queue) {

    return NULL;

  }

  queue->name = talloc_strdup(queue, name);

  if (!queue->name) {

    talloc_free(queue);

    return NULL;

  }

  queue->immediate = tevent_create_immediate(queue);

  if (!queue->immediate) {

    talloc_free(queue);

    return NULL;

  }

  queue->location = location;

  /* queue is running by default */

  queue->running = true;

  talloc_set_destructor(queue, tevent_queue_destructor);

  return queue;

}

static void tevent_queue_immediate_trigger(struct tevent_context *ev,

             struct tevent_immediate *im,

             void *private_data)

{

  struct tevent_queue *q =

    talloc_get_type_abort(private_data,

    struct tevent_queue);

  if (!q->running) {

    return;

  }

  if (!q->list) {

    return;

  }

  tevent_trace_queue_callback(ev, q->list,

            TEVENT_EVENT_TRACE_BEFORE_HANDLER);

  /* Set the call depth of the request coming from the queue. */

  tevent_thread_call_depth_notify(TEVENT_CALL_FLOW_REQ_QUEUE_TRIGGER,

          q->list->req,

          q->list->req->internal.call_depth,

          q->list->trigger_name);

  q->list->triggered = true;

  q->list->trigger(q->list->req, q->list->private_data);

}

static void tevent_queue_noop_trigger(struct tevent_req *req,

              void *_private_data)

{

  /* this is doing nothing but blocking the queue */

}

static struct tevent_queue_entry *tevent_queue_add_internal(

          struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          const char *trigger_name,

          void *private_data,

          bool allow_direct)

{

  struct tevent_queue_entry *e;

  e = talloc_zero(req, struct tevent_queue_entry);

  if (e == NULL) {

    return NULL;

  }

  /*

   * if there is no trigger, it is just a blocker

   */

  if (trigger == NULL) {

    trigger = tevent_queue_noop_trigger;

  }

  e->queue = queue;

  e->req = req;

  e->ev = ev;

  e->trigger = trigger;

  e->trigger_name = trigger_name;

  e->private_data = private_data;

  if (queue->length > 0) {

    /*

     * if there are already entries in the

     * queue do not optimize.

     */

    allow_direct = false;

  }

  if (req->async.fn != NULL) {

    /*

     * If the caller wants to optimize for the

     * empty queue case, call the trigger only

     * if there is no callback defined for the

     * request yet.

     */

    allow_direct = false;

  }

  DLIST_ADD_END(queue->list, e);

  queue->length++;

  talloc_set_destructor(e, tevent_queue_entry_destructor);

  tevent_trace_queue_callback(ev, e, TEVENT_EVENT_TRACE_ATTACH);

  tevent_thread_call_depth_notify(TEVENT_CALL_FLOW_REQ_QUEUE_ENTER,

          req,

          req->internal.call_depth,

          e->trigger_name);

  if (!queue->running) {

    return e;

  }

  if (queue->list->triggered) {

    return e;

  }

  /*

   * If allowed we directly call the trigger

   * avoiding possible delays caused by

   * an immediate event.

   */

  if (allow_direct) {

    tevent_trace_queue_callback(ev,

              queue->list,

              TEVENT_EVENT_TRACE_BEFORE_HANDLER);

    queue->list->triggered = true;

    queue->list->trigger(queue->list->req,

             queue->list->private_data);

    return e;

  }

  tevent_schedule_immediate(queue->immediate,

          queue->list->ev,

          tevent_queue_immediate_trigger,

          queue);

  return e;

}

bool tevent_queue_add(struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          void *private_data)

{

  return _tevent_queue_add(queue, ev, req, trigger, NULL, private_data);

}

bool _tevent_queue_add(struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          const char* trigger_name,

          void *private_data)

{

  struct tevent_queue_entry *e;

  e = tevent_queue_add_internal(queue, ev, req,

              trigger, trigger_name,

              private_data, false);

  if (e == NULL) {

    return false;

  }

  return true;

}

struct tevent_queue_entry *tevent_queue_add_entry(

          struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          void *private_data)

{

  return _tevent_queue_add_entry(queue, ev, req,

               trigger, NULL,

               private_data);

}

struct tevent_queue_entry *_tevent_queue_add_entry(

          struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          const char* trigger_name,

          void *private_data)

{

  return tevent_queue_add_internal(queue, ev, req,

           trigger, trigger_name,

           private_data, false);

}

struct tevent_queue_entry *tevent_queue_add_optimize_empty(

          struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          void *private_data)

{

  return _tevent_queue_add_optimize_empty(queue, ev, req,

            trigger, NULL,

            private_data);

}

struct tevent_queue_entry *_tevent_queue_add_optimize_empty(

          struct tevent_queue *queue,

          struct tevent_context *ev,

          struct tevent_req *req,

          tevent_queue_trigger_fn_t trigger,

          const char* trigger_name,

          void *private_data)

{

  return tevent_queue_add_internal(queue, ev, req,

           trigger, trigger_name,

           private_data, true);

}

void tevent_queue_entry_untrigger(struct tevent_queue_entry *entry)

{

  if (entry->queue->running) {

    abort();

  }

  if (entry->queue->list != entry) {

    abort();

  }

  entry->triggered = false;

}

void tevent_queue_start(struct tevent_queue *queue)

{

  if (queue->running) {

    /* already started */

    return;

  }

  queue->running = true;

  if (!queue->list) {

    return;

  }

  if (queue->list->triggered) {

    return;

  }

  tevent_schedule_immediate(queue->immediate,

          queue->list->ev,

          tevent_queue_immediate_trigger,

          queue);

}

void tevent_queue_stop(struct tevent_queue *queue)

{

  queue->running = false;

}

size_t tevent_queue_length(struct tevent_queue *queue)

{

  return queue->length;

}

bool tevent_queue_running(struct tevent_queue *queue)

{

  return queue->running;

}

struct tevent_queue_wait_state {

  uint8_t dummy;

};

static void tevent_queue_wait_trigger(struct tevent_req *req,

              void *private_data);

struct tevent_req *tevent_queue_wait_send(TALLOC_CTX *mem_ctx,

            struct tevent_context *ev,

            struct tevent_queue *queue)

{

  struct tevent_req *req;

  struct tevent_queue_wait_state *state;

  bool ok;

  req = tevent_req_create(mem_ctx, &state,

        struct tevent_queue_wait_state);

  if (req == NULL) {

    return NULL;

  }

  ok = _tevent_queue_add(queue, ev, req,

            tevent_queue_wait_trigger,

            "tevent_queue_wait_trigger",

            NULL);

  if (!ok) {

    tevent_req_oom(req);

    return tevent_req_post(req, ev);

  }

  return req;

}

static void tevent_queue_wait_trigger(struct tevent_req *req,

           void *private_data)

{

  tevent_req_done(req);

}

bool tevent_queue_wait_recv(struct tevent_req *req)

{

  enum tevent_req_state state;

  uint64_t err;

  if (tevent_req_is_error(req, &state, &err)) {

    tevent_req_received(req);

    return false;

  }

  tevent_req_received(req);

  return true;

}

void tevent_queue_entry_set_tag(struct tevent_queue_entry *qe, uint64_t tag)

{

  if (qe == NULL) {

    return;

  }

  qe->tag = tag;

}

uint64_t tevent_queue_entry_get_tag(const struct tevent_queue_entry *qe)

{

  if (qe == NULL) {

    return 0;

  }

  return qe->tag;

}