/*
 * Dynomite - A thin, distributed replication layer for multi non-distributed
 * storages. Copyright (C) 2014 Netflix, Inc.
 */

/*
 * twemproxy - A fast and lightweight proxy for memcached protocol.
 * Copyright (C) 2011 Twitter, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdio.h>
#include <stdlib.h>

#include <dyn_core.h>
#include <dyn_hashkit.h>
#include <dyn_server.h>

#define RANDOM_CONTINUUM_ADDITION 10 /* # extra slots to build into continuum \
                                      */
#define RANDOM_POINTS_PER_SERVER 1

rstatus_t random_update(struct server_pool *pool) {
  /* uint32_t nserver;             /\* # server - live and dead *\/ */
  /* uint32_t nlive_server;        /\* # live server *\/ */
  /* uint32_t pointer_per_server;  /\* pointers per server proportional to
   * weight *\/ */
  /* uint32_t pointer_counter;     /\* # pointers on continuum *\/ */
  /* uint32_t points_per_server;   /\* points per server *\/ */
  /* uint32_t continuum_index;     /\* continuum index *\/ */
  /* uint32_t continuum_addition;  /\* extra space in the continuum *\/ */
  /* uint32_t server_index;        /\* server index *\/ */
  /* int64_t now;                  /\* current timestamp in usec *\/ */

  /* now = dn_usec_now(); */
  /* if (now < 0) { */
  /*     return DN_ERROR; */
  /* } */

  /* nserver = array_n(&pool->server); */
  /* nlive_server = 0; */
  /* pool->next_rebuild = 0LL; */

  /* for (server_index = 0; server_index < nserver; server_index++) { */
  /*     struct server *server = array_get(&pool->server, server_index); */

  /*     if (pool->auto_eject_hosts) { */
  /*         if (server->next_retry <= now) { */
  /*             server->next_retry = 0LL; */
  /*             nlive_server++; */
  /*         } else if (pool->next_rebuild == 0LL || */
  /*                    server->next_retry < pool->next_rebuild) { */
  /*             pool->next_rebuild = server->next_retry; */
  /*         } */
  /*     } else { */
  /*         nlive_server++; */
  /*     } */
  /* } */

  /* pool->nlive_server = nlive_server; */

  /* if (nlive_server == 0) { */
  /*     ASSERT(pool->continuum != NULL); */
  /*     ASSERT(pool->ncontinuum != 0); */

  /*     log_debug(LOG_DEBUG, "no live servers for pool %"PRIu32" '%.*s'", */
  /*               pool->idx, pool->name.len, pool->name.data); */

  /*     return DN_OK; */
  /* } */
  /* log_debug(LOG_DEBUG, "%"PRIu32" of %"PRIu32" servers are live for pool " */
  /*           "%"PRIu32" '%.*s'", nlive_server, nserver, pool->idx, */
  /*           pool->name.len, pool->name.data); */

  /* continuum_addition = RANDOM_CONTINUUM_ADDITION; */
  /* points_per_server = RANDOM_POINTS_PER_SERVER; */

  /* /\* */
  /*  * Allocate the continuum for the pool, the first time, and every time we
   */
  /*  * add a new server to the pool */
  /*  *\/ */
  /* if (nlive_server > pool->nserver_continuum) { */
  /*     struct continuum *continuum; */
  /*     uint32_t nserver_continuum = nlive_server + RANDOM_CONTINUUM_ADDITION;
   */
  /*     uint32_t ncontinuum = nserver_continuum *  RANDOM_POINTS_PER_SERVER; */

  /*     continuum = dn_realloc(pool->continuum, sizeof(*continuum) *
   * ncontinuum); */
  /*     if (continuum == NULL) { */
  /*         return DN_ENOMEM; */
  /*     } */

  /*     srandom((uint32_t)time(NULL)); */

  /*     pool->continuum = continuum; */
  /*     pool->nserver_continuum = nserver_continuum; */
  /*     /\* pool->ncontinuum is initialized later as it could be <= ncontinuum
   * *\/ */
  /* } */

  /* /\* update the continuum with the servers that are live *\/ */
  /* continuum_index = 0; */
  /* pointer_counter = 0; */
  /* for (server_index = 0; server_index < nserver; server_index++) { */
  /*     struct server *server = array_get(&pool->server, server_index); */

  /*     if (pool->auto_eject_hosts && server->next_retry > now) { */
  /*         continue; */
  /*     } */

  /*     pointer_per_server = 1; */

  /*     pool->continuum[continuum_index].index = server_index; */
  /*     pool->continuum[continuum_index++].value = 0; */

  /*     pointer_counter += pointer_per_server; */
  /* } */
  /* pool->ncontinuum = pointer_counter; */

  /* log_debug(LOG_VERB, "updated pool %"PRIu32" '%.*s' with %"PRIu32" of " */
  /*           "%"PRIu32" servers live in %"PRIu32" slots and %"PRIu32" " */
  /*           "active points in %"PRIu32" slots", pool->idx, */
  /*           pool->name.len, pool->name.data, nlive_server, nserver, */
  /*           pool->nserver_continuum, pool->ncontinuum, */
  /*           (pool->nserver_continuum + continuum_addition) *
   * points_per_server); */

  return DN_OK;
}

uint32_t random_dispatch(struct continuum *continuum, uint32_t ncontinuum,
                         uint32_t hash) {
  struct continuum *c;

  ASSERT(continuum != NULL);
  ASSERT(ncontinuum != 0);

  c = continuum + random() % ncontinuum;

  return c->index;
}
