gnunet-service-datastore.c

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/*
     This file is part of GNUnet
     Copyright (C) 2004-2014, 2016 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_statistics_service.h"
#include "gnunet_datastore_plugin.h"
#include "datastore.h"

#define MAX_PENDING 1024

#define MAX_BF_SIZE ((uint32_t)(1LL << 31))

#define MAX_EXPIRE_DELAY \
  GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 15)

#define MIN_EXPIRE_DELAY \
  GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS, 1)

static char *quota_stat_name;

static struct GNUNET_SCHEDULER_Task *stat_timeout_task;

#define MAX_STAT_SYNC_LAG 50


struct DatastorePlugin {
  struct GNUNET_DATASTORE_PluginFunctions *api;

  char *short_name;

  char *lib_name;

  struct GNUNET_DATASTORE_PluginEnvironment env;
};


struct ReservationList {
  struct ReservationList *next;

  struct GNUNET_SERVICE_Client *client;

  uint64_t amount;

  uint64_t entries;

  int32_t rid;
};


static struct DatastorePlugin *plugin;

static struct ReservationList *reservations;

static struct GNUNET_CONTAINER_BloomFilter *filter;

static char *plugin_name;

static const struct GNUNET_CONFIGURATION_Handle *cfg;

static struct GNUNET_STATISTICS_Handle *stats;

static unsigned long long cache_size;

static unsigned long long reserved;

static unsigned long long payload;

static struct GNUNET_SCHEDULER_Task *expired_kill_task;

static struct GNUNET_TIME_Absolute min_expiration;

static unsigned long long quota;

static int do_drop;

static int refresh_bf;

static unsigned int last_sync;

static int stats_worked;


static void
sync_stats()
{
  GNUNET_STATISTICS_set(stats, quota_stat_name, payload, GNUNET_YES);
  GNUNET_STATISTICS_set(stats,
                        "# utilization by current datastore",
                        payload,
                        GNUNET_NO);
  last_sync = 0;
}


static int cleaning_done;

static struct GNUNET_STATISTICS_GetHandle *stat_get;

static struct GNUNET_SERVICE_Handle *service;

static void
delete_expired(void *cls);


static int
expired_processor(void *cls,
                  const struct GNUNET_HashCode *key,
                  uint32_t size,
                  const void *data,
                  enum GNUNET_BLOCK_Type type,
                  uint32_t priority,
                  uint32_t anonymity,
                  uint32_t replication,
                  struct GNUNET_TIME_Absolute expiration,
                  uint64_t uid)
{
  struct GNUNET_TIME_Absolute now;

  if (NULL == key)
    {
      expired_kill_task =
        GNUNET_SCHEDULER_add_delayed_with_priority(MAX_EXPIRE_DELAY,
                                                   GNUNET_SCHEDULER_PRIORITY_IDLE,
                                                   &delete_expired,
                                                   NULL);
      return GNUNET_SYSERR;
    }
  now = GNUNET_TIME_absolute_get();
  if (expiration.abs_value_us > now.abs_value_us)
    {
      /* finished processing */
      expired_kill_task =
        GNUNET_SCHEDULER_add_delayed_with_priority(MAX_EXPIRE_DELAY,
                                                   GNUNET_SCHEDULER_PRIORITY_IDLE,
                                                   &delete_expired,
                                                   NULL);
      return GNUNET_SYSERR;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Deleting content `%s' of type %u that expired %s ago\n",
             GNUNET_h2s(key),
             type,
             GNUNET_STRINGS_relative_time_to_string(
               GNUNET_TIME_absolute_get_difference(expiration, now),
               GNUNET_YES));
  min_expiration = now;
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# bytes expired"),
                           size,
                           GNUNET_YES);
  GNUNET_CONTAINER_bloomfilter_remove(filter, key);
  expired_kill_task =
    GNUNET_SCHEDULER_add_delayed_with_priority(MIN_EXPIRE_DELAY,
                                               GNUNET_SCHEDULER_PRIORITY_IDLE,
                                               &delete_expired,
                                               NULL);
  return GNUNET_NO;
}


static void
delete_expired(void *cls)
{
  expired_kill_task = NULL;
  plugin->api->get_expiration(plugin->api->cls, &expired_processor, NULL);
}


static int
quota_processor(void *cls,
                const struct GNUNET_HashCode *key,
                uint32_t size,
                const void *data,
                enum GNUNET_BLOCK_Type type,
                uint32_t priority,
                uint32_t anonymity,
                uint32_t replication,
                struct GNUNET_TIME_Absolute expiration,
                uint64_t uid)
{
  unsigned long long *need = cls;

  if (NULL == key)
    return GNUNET_SYSERR;
  GNUNET_log(
    GNUNET_ERROR_TYPE_DEBUG,
    "Deleting %llu bytes of low-priority (%u) content `%s' of type %u at %s prior to expiration (still trying to free another %llu bytes)\n",
    (unsigned long long)(size + GNUNET_DATASTORE_ENTRY_OVERHEAD),
    (unsigned int)priority,
    GNUNET_h2s(key),
    type,
    GNUNET_STRINGS_relative_time_to_string(GNUNET_TIME_absolute_get_remaining(
                                             expiration),
                                           GNUNET_YES),
    *need);
  if (size + GNUNET_DATASTORE_ENTRY_OVERHEAD > *need)
    *need = 0;
  else
    *need -= size + GNUNET_DATASTORE_ENTRY_OVERHEAD;
  if (priority > 0)
    min_expiration = GNUNET_TIME_UNIT_FOREVER_ABS;
  else
    min_expiration = expiration;
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# bytes purged (low-priority)"),
                           size,
                           GNUNET_YES);
  GNUNET_CONTAINER_bloomfilter_remove(filter, key);
  return GNUNET_NO;
}


static void
manage_space(unsigned long long need)
{
  unsigned long long last;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Asked to free up %llu bytes of cache space\n",
             need);
  last = 0;
  while ((need > 0) && (last != need))
    {
      last = need;
      plugin->api->get_expiration(plugin->api->cls, &quota_processor, &need);
    }
}


static void
transmit_status(struct GNUNET_SERVICE_Client *client,
                int code,
                const char *msg)
{
  struct GNUNET_MQ_Envelope *env;
  struct StatusMessage *sm;
  size_t slen;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Transmitting `%s' message with value %d and message `%s'\n",
             "STATUS",
             code,
             msg != NULL ? msg : "(none)");
  slen = (msg == NULL) ? 0 : strlen(msg) + 1;
  env = GNUNET_MQ_msg_extra(sm, slen, GNUNET_MESSAGE_TYPE_DATASTORE_STATUS);
  sm->status = htonl(code);
  sm->min_expiration = GNUNET_TIME_absolute_hton(min_expiration);
  GNUNET_memcpy(&sm[1], msg, slen);
  GNUNET_MQ_send(GNUNET_SERVICE_client_get_mq(client), env);
}


static int
transmit_item(void *cls,
              const struct GNUNET_HashCode *key,
              uint32_t size,
              const void *data,
              enum GNUNET_BLOCK_Type type,
              uint32_t priority,
              uint32_t anonymity,
              uint32_t replication,
              struct GNUNET_TIME_Absolute expiration,
              uint64_t uid)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_MessageHeader *end;
  struct DataMessage *dm;

  if (NULL == key)
    {
      /* transmit 'DATA_END' */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Transmitting DATA_END message\n");
      env = GNUNET_MQ_msg(end, GNUNET_MESSAGE_TYPE_DATASTORE_DATA_END);
      GNUNET_MQ_send(GNUNET_SERVICE_client_get_mq(client), env);
      return GNUNET_OK;
    }
  GNUNET_assert(sizeof(struct DataMessage) + size < GNUNET_MAX_MESSAGE_SIZE);
  env = GNUNET_MQ_msg_extra(dm, size, GNUNET_MESSAGE_TYPE_DATASTORE_DATA);
  dm->rid = htonl(0);
  dm->size = htonl(size);
  dm->type = htonl(type);
  dm->priority = htonl(priority);
  dm->anonymity = htonl(anonymity);
  dm->replication = htonl(replication);
  dm->expiration = GNUNET_TIME_absolute_hton(expiration);
  dm->uid = GNUNET_htonll(uid);
  dm->key = *key;
  GNUNET_memcpy(&dm[1], data, size);
  GNUNET_log(
    GNUNET_ERROR_TYPE_DEBUG,
    "Transmitting DATA message for `%s' of type %u with expiration %s (in: %s)\n",
    GNUNET_h2s(key),
    type,
    GNUNET_STRINGS_absolute_time_to_string(expiration),
    GNUNET_STRINGS_relative_time_to_string(GNUNET_TIME_absolute_get_remaining(
                                             expiration),
                                           GNUNET_YES));
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# results found"),
                           1,
                           GNUNET_NO);
  GNUNET_MQ_send(GNUNET_SERVICE_client_get_mq(client), env);
  return GNUNET_OK;
}


static void
handle_reserve(void *cls, const struct ReserveMessage *msg)
{
  static int reservation_gen;
  struct GNUNET_SERVICE_Client *client = cls;
  struct ReservationList *e;
  unsigned long long used;
  unsigned long long req;
  uint64_t amount;
  uint32_t entries;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Processing RESERVE request\n");
  amount = GNUNET_ntohll(msg->amount);
  entries = ntohl(msg->entries);
  used = payload + reserved;
  req =
    amount + ((unsigned long long)GNUNET_DATASTORE_ENTRY_OVERHEAD) * entries;
  if (used + req > quota)
    {
      if (quota < used)
        used =
          quota; /* cheat a bit for error message (to avoid negative numbers) */
      GNUNET_log(
        GNUNET_ERROR_TYPE_WARNING,
        _(
          "Insufficient space (%llu bytes are available) to satisfy RESERVE request for %llu bytes\n"),
        quota - used,
        req);
      if (cache_size < req)
        {
          /* TODO: document this in the FAQ; essentially, if this
           * message happens, the insertion request could be blocked
           * by less-important content from migration because it is
           * larger than 1/8th of the overall available space, and
           * we only reserve 1/8th for "fresh" insertions */
          GNUNET_log(
            GNUNET_ERROR_TYPE_WARNING,
            _(
              "The requested amount (%llu bytes) is larger than the cache size (%llu bytes)\n"),
            req,
            cache_size);
          transmit_status(client,
                          0,
                          gettext_noop(
                            "Insufficient space to satisfy request and "
                            "requested amount is larger than cache size"));
        }
      else
        {
          transmit_status(client,
                          0,
                          gettext_noop("Insufficient space to satisfy request"));
        }
      GNUNET_SERVICE_client_continue(client);
      return;
    }
  reserved += req;
  GNUNET_STATISTICS_set(stats,
                        gettext_noop("# reserved"),
                        reserved,
                        GNUNET_NO);
  e = GNUNET_new(struct ReservationList);
  e->next = reservations;
  reservations = e;
  e->client = client;
  e->amount = amount;
  e->entries = entries;
  e->rid = ++reservation_gen;
  if (reservation_gen < 0)
    reservation_gen = 0; /* wrap around */
  transmit_status(client, e->rid, NULL);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_release_reserve(void *cls, const struct ReleaseReserveMessage *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct ReservationList *pos;
  struct ReservationList *prev;
  struct ReservationList *next;
  int rid = ntohl(msg->rid);
  unsigned long long rem;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Processing RELEASE_RESERVE request\n");
  next = reservations;
  prev = NULL;
  while (NULL != (pos = next))
    {
      next = pos->next;
      if (rid == pos->rid)
        {
          if (prev == NULL)
            reservations = next;
          else
            prev->next = next;
          rem =
            pos->amount +
            ((unsigned long long)GNUNET_DATASTORE_ENTRY_OVERHEAD) * pos->entries;
          GNUNET_assert(reserved >= rem);
          reserved -= rem;
          GNUNET_STATISTICS_set(stats,
                                gettext_noop("# reserved"),
                                reserved,
                                GNUNET_NO);
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                     "Returning %llu remaining reserved bytes to storage pool\n",
                     rem);
          GNUNET_free(pos);
          transmit_status(client, GNUNET_OK, NULL);
          GNUNET_SERVICE_client_continue(client);
          return;
        }
      prev = pos;
    }
  GNUNET_break(0);
  transmit_status(client,
                  GNUNET_SYSERR,
                  gettext_noop("Could not find matching reservation"));
  GNUNET_SERVICE_client_continue(client);
}


static int
check_data(const struct DataMessage *dm)
{
  uint16_t size;
  uint32_t dsize;

  size = ntohs(dm->header.size);
  dsize = ntohl(dm->size);
  if (size != dsize + sizeof(struct DataMessage))
    {
      GNUNET_break(0);
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}


static void
put_continuation(void *cls,
                 const struct GNUNET_HashCode *key,
                 uint32_t size,
                 int status,
                 const char *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;

  if (GNUNET_OK == status)
    {
      GNUNET_STATISTICS_update(stats,
                               gettext_noop("# bytes stored"),
                               size,
                               GNUNET_YES);
      GNUNET_CONTAINER_bloomfilter_add(filter, key);
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Successfully stored %u bytes under key `%s'\n",
                 size,
                 GNUNET_h2s(key));
    }
  transmit_status(client,
                  GNUNET_SYSERR == status ? GNUNET_SYSERR : GNUNET_OK,
                  msg);
  if (quota - reserved - cache_size < payload)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("Need %llu bytes more space (%llu allowed, using %llu)\n"),
                 (unsigned long long)size + GNUNET_DATASTORE_ENTRY_OVERHEAD,
                 (unsigned long long)(quota - reserved - cache_size),
                 (unsigned long long)payload);
      manage_space(size + GNUNET_DATASTORE_ENTRY_OVERHEAD);
    }
}


static int
check_put(void *cls, const struct DataMessage *dm)
{
  if (GNUNET_OK != check_data(dm))
    {
      GNUNET_break(0);
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}


static void
handle_put(void *cls, const struct DataMessage *dm)
{
  struct GNUNET_SERVICE_Client *client = cls;
  int rid;
  struct ReservationList *pos;
  uint32_t size;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Processing PUT request for `%s' of type %u\n",
             GNUNET_h2s(&dm->key),
             (uint32_t)ntohl(dm->type));
  rid = ntohl(dm->rid);
  size = ntohl(dm->size);
  if (rid > 0)
    {
      pos = reservations;
      while ((NULL != pos) && (rid != pos->rid))
        pos = pos->next;
      GNUNET_break(pos != NULL);
      if (NULL != pos)
        {
          GNUNET_break(pos->entries > 0);
          GNUNET_break(pos->amount >= size);
          pos->entries--;
          pos->amount -= size;
          reserved -= (size + GNUNET_DATASTORE_ENTRY_OVERHEAD);
          GNUNET_STATISTICS_set(stats,
                                gettext_noop("# reserved"),
                                reserved,
                                GNUNET_NO);
        }
    }
  bool absent =
    GNUNET_NO == GNUNET_CONTAINER_bloomfilter_test(filter, &dm->key);
  plugin->api->put(plugin->api->cls,
                   &dm->key,
                   absent,
                   ntohl(dm->size),
                   &dm[1],
                   ntohl(dm->type),
                   ntohl(dm->priority),
                   ntohl(dm->anonymity),
                   ntohl(dm->replication),
                   GNUNET_TIME_absolute_ntoh(dm->expiration),
                   &put_continuation,
                   client);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_get(void *cls, const struct GetMessage *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Processing GET request of type %u\n",
             (uint32_t)ntohl(msg->type));
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# GET requests received"),
                           1,
                           GNUNET_NO);
  plugin->api->get_key(plugin->api->cls,
                       GNUNET_ntohll(msg->next_uid),
                       msg->random,
                       NULL,
                       ntohl(msg->type),
                       &transmit_item,
                       client);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_get_key(void *cls, const struct GetKeyMessage *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Processing GET request for `%s' of type %u\n",
             GNUNET_h2s(&msg->key),
             (uint32_t)ntohl(msg->type));
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# GET KEY requests received"),
                           1,
                           GNUNET_NO);
  if (GNUNET_YES != GNUNET_CONTAINER_bloomfilter_test(filter, &msg->key))
    {
      /* don't bother database... */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Empty result set for GET request for `%s' (bloomfilter).\n",
                 GNUNET_h2s(&msg->key));
      GNUNET_STATISTICS_update(stats,
                               gettext_noop(
                                 "# requests filtered by bloomfilter"),
                               1,
                               GNUNET_NO);
      transmit_item(client,
                    NULL,
                    0,
                    NULL,
                    0,
                    0,
                    0,
                    0,
                    GNUNET_TIME_UNIT_ZERO_ABS,
                    0);
      GNUNET_SERVICE_client_continue(client);
      return;
    }
  plugin->api->get_key(plugin->api->cls,
                       GNUNET_ntohll(msg->next_uid),
                       msg->random,
                       &msg->key,
                       ntohl(msg->type),
                       &transmit_item,
                       client);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_get_replication(void *cls, const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_SERVICE_Client *client = cls;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Processing GET_REPLICATION request\n");
  GNUNET_STATISTICS_update(stats,
                           gettext_noop(
                             "# GET REPLICATION requests received"),
                           1,
                           GNUNET_NO);
  plugin->api->get_replication(plugin->api->cls, &transmit_item, client);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_get_zero_anonymity(void *cls, const struct GetZeroAnonymityMessage *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  enum GNUNET_BLOCK_Type type;

  type = (enum GNUNET_BLOCK_Type)ntohl(msg->type);
  if (type == GNUNET_BLOCK_TYPE_ANY)
    {
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Processing GET_ZERO_ANONYMITY request\n");
  GNUNET_STATISTICS_update(stats,
                           gettext_noop(
                             "# GET ZERO ANONYMITY requests received"),
                           1,
                           GNUNET_NO);
  plugin->api->get_zero_anonymity(plugin->api->cls,
                                  GNUNET_ntohll(msg->next_uid),
                                  type,
                                  &transmit_item,
                                  client);
  GNUNET_SERVICE_client_continue(client);
}


static void
remove_continuation(void *cls,
                    const struct GNUNET_HashCode *key,
                    uint32_t size,
                    int status,
                    const char *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;

  if (GNUNET_SYSERR == status)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "REMOVE request failed: %s.\n", msg);
      transmit_status(client, GNUNET_NO, msg);
      return;
    }
  if (GNUNET_NO == status)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Content not found for REMOVE request.\n");
      transmit_status(client, GNUNET_NO, _("Content not found"));
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Item matches REMOVE request for key `%s'.\n",
             GNUNET_h2s(key));
  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# bytes removed (explicit request)"),
                           size,
                           GNUNET_YES);
  GNUNET_CONTAINER_bloomfilter_remove(filter, key);
  transmit_status(client, GNUNET_OK, NULL);
}


static int
check_remove(void *cls, const struct DataMessage *dm)
{
  if (GNUNET_OK != check_data(dm))
    {
      GNUNET_break(0);
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}


static void
handle_remove(void *cls, const struct DataMessage *dm)
{
  struct GNUNET_SERVICE_Client *client = cls;

  GNUNET_STATISTICS_update(stats,
                           gettext_noop("# REMOVE requests received"),
                           1,
                           GNUNET_NO);
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Processing REMOVE request for `%s'\n",
             GNUNET_h2s(&dm->key));
  plugin->api->remove_key(plugin->api->cls,
                          &dm->key,
                          ntohl(dm->size),
                          &dm[1],
                          &remove_continuation,
                          client);
  GNUNET_SERVICE_client_continue(client);
}


static void
handle_drop(void *cls, const struct GNUNET_MessageHeader *message)
{
  struct GNUNET_SERVICE_Client *client = cls;

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Processing DROP request\n");
  do_drop = GNUNET_YES;
  GNUNET_SERVICE_client_continue(client);
}


static void
disk_utilization_change_cb(void *cls, int delta)
{
  if ((delta < 0) && (payload < -delta))
    {
      GNUNET_log(
        GNUNET_ERROR_TYPE_WARNING,
        _(
          "Datastore payload must have been inaccurate (%lld < %lld). Recomputing it.\n"),
        (long long)payload,
        (long long)-delta);
      plugin->api->estimate_size(plugin->api->cls, &payload);
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("New payload: %lld\n"),
                 (long long)payload);
      sync_stats();
      return;
    }
  payload += delta;
  last_sync++;
  if (last_sync >= MAX_STAT_SYNC_LAG)
    sync_stats();
}


static int
process_stat_in(void *cls,
                const char *subsystem,
                const char *name,
                uint64_t value,
                int is_persistent)
{
  GNUNET_assert(GNUNET_NO == stats_worked);
  stats_worked = GNUNET_YES;
  payload += value;
  GNUNET_log(
    GNUNET_ERROR_TYPE_DEBUG,
    "Notification from statistics about existing payload (%llu), new payload is %llu\n",
    (unsigned long long)value,
    (unsigned long long)payload);
  return GNUNET_OK;
}


static struct DatastorePlugin *
load_plugin()
{
  struct DatastorePlugin *ret;
  char *libname;

  ret = GNUNET_new(struct DatastorePlugin);
  ret->env.cfg = cfg;
  ret->env.duc = &disk_utilization_change_cb;
  ret->env.cls = NULL;
  GNUNET_log(GNUNET_ERROR_TYPE_INFO,
             _("Loading `%s' datastore plugin\n"),
             plugin_name);
  GNUNET_asprintf(&libname, "libgnunet_plugin_datastore_%s", plugin_name);
  ret->short_name = GNUNET_strdup(plugin_name);
  ret->lib_name = libname;
  ret->api = GNUNET_PLUGIN_load(libname, &ret->env);
  if (NULL == ret->api)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                 _("Failed to load datastore plugin for `%s'\n"),
                 plugin_name);
      GNUNET_free(ret->short_name);
      GNUNET_free(libname);
      GNUNET_free(ret);
      return NULL;
    }
  return ret;
}


static void
unload_plugin(struct DatastorePlugin *plug)
{
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Datastore service is unloading plugin...\n");
  GNUNET_break(NULL == GNUNET_PLUGIN_unload(plug->lib_name, plug->api));
  GNUNET_free(plug->lib_name);
  GNUNET_free(plug->short_name);
  GNUNET_free(plug);
}


static void
begin_service()
{
  GNUNET_SERVICE_resume(service);
  expired_kill_task =
    GNUNET_SCHEDULER_add_with_priority(GNUNET_SCHEDULER_PRIORITY_IDLE,
                                       &delete_expired,
                                       NULL);
}


static void
add_key_to_bloomfilter(void *cls,
                       const struct GNUNET_HashCode *key,
                       unsigned int count)
{
  struct GNUNET_CONTAINER_BloomFilter *bf = cls;

  if (NULL == key)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("Bloomfilter construction complete.\n"));
      begin_service();
      return;
    }

  while (0 < count--)
    GNUNET_CONTAINER_bloomfilter_add(bf, key);
}


static void
process_stat_done(void *cls, int success)
{
  stat_get = NULL;
  if (NULL != stat_timeout_task)
    {
      GNUNET_SCHEDULER_cancel(stat_timeout_task);
      stat_timeout_task = NULL;
    }
  plugin = load_plugin();
  if (NULL == plugin)
    {
      GNUNET_CONTAINER_bloomfilter_free(filter);
      filter = NULL;
      if (NULL != stats)
        {
          GNUNET_STATISTICS_destroy(stats, GNUNET_YES);
          stats = NULL;
        }
      return;
    }

  if (GNUNET_NO == stats_worked)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Failed to obtain value from statistics service, recomputing it\n");
      plugin->api->estimate_size(plugin->api->cls, &payload);
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("New payload: %lld\n"),
                 (long long)payload);
    }

  if (GNUNET_YES == refresh_bf)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("Rebuilding bloomfilter.  Please be patient.\n"));
      if (NULL != plugin->api->get_keys)
        {
          plugin->api->get_keys(plugin->api->cls, &add_key_to_bloomfilter, filter);
          return;
        }
      else
        {
          GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                     _(
                       "Plugin does not support get_keys function. Please fix!\n"));
        }
    }
  begin_service();
}


static void
stat_timeout(void *cls)
{
  stat_timeout_task = NULL;
  GNUNET_STATISTICS_get_cancel(stat_get);
  process_stat_done(NULL, GNUNET_NO);
}


static void
cleaning_task(void *cls)
{
  cleaning_done = GNUNET_YES;
  if (NULL != expired_kill_task)
    {
      GNUNET_SCHEDULER_cancel(expired_kill_task);
      expired_kill_task = NULL;
    }
  if (GNUNET_YES == do_drop)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Dropping database!\n");
      plugin->api->drop(plugin->api->cls);
      payload = 0;
      last_sync++;
    }
  if (NULL != plugin)
    {
      unload_plugin(plugin);
      plugin = NULL;
    }
  if (NULL != filter)
    {
      GNUNET_CONTAINER_bloomfilter_free(filter);
      filter = NULL;
    }
  if (NULL != stat_get)
    {
      GNUNET_STATISTICS_get_cancel(stat_get);
      stat_get = NULL;
    }
  if (NULL != stat_timeout_task)
    {
      GNUNET_SCHEDULER_cancel(stat_timeout_task);
      stat_timeout_task = NULL;
    }
  GNUNET_free_non_null(plugin_name);
  plugin_name = NULL;
  if (last_sync > 0)
    sync_stats();
  if (NULL != stats)
    {
      GNUNET_STATISTICS_destroy(stats, GNUNET_YES);
      stats = NULL;
    }
  GNUNET_free(quota_stat_name);
  quota_stat_name = NULL;
}


static void *
client_connect_cb(void *cls,
                  struct GNUNET_SERVICE_Client *client,
                  struct GNUNET_MQ_Handle *mq)
{
  return client;
}


static void
client_disconnect_cb(void *cls,
                     struct GNUNET_SERVICE_Client *client,
                     void *app_ctx)
{
  struct ReservationList *pos;
  struct ReservationList *prev;
  struct ReservationList *next;

  GNUNET_assert(app_ctx == client);
  prev = NULL;
  pos = reservations;
  while (NULL != pos)
    {
      next = pos->next;
      if (pos->client == client)
        {
          if (NULL == prev)
            reservations = next;
          else
            prev->next = next;
          reserved -= pos->amount + pos->entries * GNUNET_DATASTORE_ENTRY_OVERHEAD;
          GNUNET_free(pos);
        }
      else
        {
          prev = pos;
        }
      pos = next;
    }
  GNUNET_STATISTICS_set(stats,
                        gettext_noop("# reserved"),
                        reserved,
                        GNUNET_NO);
}


static void
run(void *cls,
    const struct GNUNET_CONFIGURATION_Handle *c,
    struct GNUNET_SERVICE_Handle *serv)
{
  char *fn;
  char *pfn;
  unsigned int bf_size;

  service = serv;
  cfg = c;
  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_string(cfg,
                                                         "DATASTORE",
                                                         "DATABASE",
                                                         &plugin_name))
    {
      GNUNET_log_config_missing(GNUNET_ERROR_TYPE_ERROR,
                                "DATABASE",
                                "DATASTORE");
      return;
    }
  GNUNET_asprintf(&quota_stat_name,
                  _("# bytes used in file-sharing datastore `%s'"),
                  plugin_name);
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_size(cfg, "DATASTORE", "QUOTA", &quota))
    {
      GNUNET_log_config_missing(GNUNET_ERROR_TYPE_ERROR, "QUOTA", "DATASTORE");
      return;
    }
  stats = GNUNET_STATISTICS_create("datastore", cfg);
  GNUNET_STATISTICS_set(stats, gettext_noop("# quota"), quota, GNUNET_NO);
  cache_size = quota / 8; /* Or should we make this an option? */
  GNUNET_STATISTICS_set(stats,
                        gettext_noop("# cache size"),
                        cache_size,
                        GNUNET_NO);
  if (quota / (32 * 1024LL) > MAX_BF_SIZE)
    bf_size = MAX_BF_SIZE;
  else
    bf_size =
      quota / (32 * 1024LL); /* 8 bit per entry, 1 bit per 32 kb in DB */
  fn = NULL;
  if ((GNUNET_OK != GNUNET_CONFIGURATION_get_value_filename(cfg,
                                                            "DATASTORE",
                                                            "BLOOMFILTER",
                                                            &fn)) ||
      (GNUNET_OK != GNUNET_DISK_directory_create_for_file(fn)))
    {
      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
                 _("Could not use specified filename `%s' for bloomfilter.\n"),
                 NULL != fn ? fn : "");
      GNUNET_free_non_null(fn);
      fn = NULL;
    }
  if (NULL != fn)
    {
      GNUNET_asprintf(&pfn, "%s.%s", fn, plugin_name);
      if (GNUNET_YES == GNUNET_DISK_file_test(pfn))
        {
          filter =
            GNUNET_CONTAINER_bloomfilter_load(pfn,
                                              bf_size,
                                              5); /* approx. 3% false positives at max use */
          if (NULL == filter)
            {
              /* file exists but not valid, remove and try again, but refresh */
              if (0 != unlink(pfn))
                {
                  /* failed to remove, run without file */
                  GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                             _("Failed to remove bogus bloomfilter file `%s'\n"),
                             pfn);
                  GNUNET_free(pfn);
                  pfn = NULL;
                  filter = GNUNET_CONTAINER_bloomfilter_load(
                    NULL,
                    bf_size,
                    5); /* approx. 3% false positives at max use */
                  refresh_bf = GNUNET_YES;
                }
              else
                {
                  /* try again after remove */
                  filter = GNUNET_CONTAINER_bloomfilter_load(
                    pfn,
                    bf_size,
                    5); /* approx. 3% false positives at max use */
                  refresh_bf = GNUNET_YES;
                  if (NULL == filter)
                    {
                      /* failed yet again, give up on using file */
                      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                                 _("Failed to remove bogus bloomfilter file `%s'\n"),
                                 pfn);
                      GNUNET_free(pfn);
                      pfn = NULL;
                      filter = GNUNET_CONTAINER_bloomfilter_init(
                        NULL,
                        bf_size,
                        5); /* approx. 3% false positives at max use */
                    }
                }
            }
          else
            {
              /* normal case: have an existing valid bf file, no need to refresh */
              refresh_bf = GNUNET_NO;
            }
        }
      else
        {
          filter =
            GNUNET_CONTAINER_bloomfilter_load(pfn,
                                              bf_size,
                                              5); /* approx. 3% false positives at max use */
          refresh_bf = GNUNET_YES;
        }
      GNUNET_free(pfn);
    }
  else
    {
      filter =
        GNUNET_CONTAINER_bloomfilter_init(NULL,
                                          bf_size,
                                          5); /* approx. 3% false positives at max use */
      refresh_bf = GNUNET_YES;
    }
  GNUNET_free_non_null(fn);
  if (NULL == filter)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                 _("Failed to initialize bloomfilter.\n"));
      if (NULL != stats)
        {
          GNUNET_STATISTICS_destroy(stats, GNUNET_YES);
          stats = NULL;
        }
      return;
    }
  GNUNET_SERVICE_suspend(service);
  stat_get = GNUNET_STATISTICS_get(stats,
                                   "datastore",
                                   quota_stat_name,
                                   &process_stat_done,
                                   &process_stat_in,
                                   NULL);
  if (NULL == stat_get)
    process_stat_done(NULL, GNUNET_SYSERR);
  else
    stat_timeout_task = GNUNET_SCHEDULER_add_delayed(GNUNET_TIME_UNIT_SECONDS,
                                                     &stat_timeout,
                                                     NULL);
  GNUNET_SCHEDULER_add_shutdown(&cleaning_task, NULL);
}


GNUNET_SERVICE_MAIN(
  "datastore",
  GNUNET_SERVICE_OPTION_NONE,
  &run,
  &client_connect_cb,
  &client_disconnect_cb,
  NULL,
  GNUNET_MQ_hd_fixed_size(reserve,
                          GNUNET_MESSAGE_TYPE_DATASTORE_RESERVE,
                          struct ReserveMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(release_reserve,
                          GNUNET_MESSAGE_TYPE_DATASTORE_RELEASE_RESERVE,
                          struct ReleaseReserveMessage,
                          NULL),
  GNUNET_MQ_hd_var_size(put,
                        GNUNET_MESSAGE_TYPE_DATASTORE_PUT,
                        struct DataMessage,
                        NULL),
  GNUNET_MQ_hd_fixed_size(get,
                          GNUNET_MESSAGE_TYPE_DATASTORE_GET,
                          struct GetMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(get_key,
                          GNUNET_MESSAGE_TYPE_DATASTORE_GET_KEY,
                          struct GetKeyMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(get_replication,
                          GNUNET_MESSAGE_TYPE_DATASTORE_GET_REPLICATION,
                          struct GNUNET_MessageHeader,
                          NULL),
  GNUNET_MQ_hd_fixed_size(get_zero_anonymity,
                          GNUNET_MESSAGE_TYPE_DATASTORE_GET_ZERO_ANONYMITY,
                          struct GetZeroAnonymityMessage,
                          NULL),
  GNUNET_MQ_hd_var_size(remove,
                        GNUNET_MESSAGE_TYPE_DATASTORE_REMOVE,
                        struct DataMessage,
                        NULL),
  GNUNET_MQ_hd_fixed_size(drop,
                          GNUNET_MESSAGE_TYPE_DATASTORE_DROP,
                          struct GNUNET_MessageHeader,
                          NULL),
  GNUNET_MQ_handler_end());


/* end of gnunet-service-datastore.c */