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path: root/src/ats/gnunet-service-ats_normalization.c
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/*
 This file is part of GNUnet.
 (C) 2011 Christian Grothoff (and other contributing authors)

 GNUnet 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 3, 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
 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with GNUnet; see the file COPYING.  If not, write to the
 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 Boston, MA 02111-1307, USA.
 */

/**
 * @file ats/gnunet-service-ats_normalization.c
 * @brief ats service address: management of ATS properties and preferences normalization
 * @author Matthias Wachs
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_ats_service.h"
#include "gnunet-service-ats_addresses.h"
#include "gnunet-service-ats_normalization.h"

#define LOG(kind,...) GNUNET_log_from (kind, "ats-normalization",__VA_ARGS__)

/**
 * Preference client
 */
struct PreferenceClient
{
  /**
   * Next in DLL
   */
  struct PreferenceClient *prev;

  /**
   * Next in DLL
   */

  struct PreferenceClient *next;

  /**
   * Client handle
   */
  void *client;

  /**
   * Total preference for this peer
   */
  double f_abs_sum[GNUNET_ATS_PreferenceCount];

  /**
   * List of peer preferences for this client
   */

  /**
   * Head of peer list
   */
  struct PreferencePeer *p_head;

  /**
   * Tail of peer list
   */
  struct PreferencePeer *p_tail;
};

/**
 * Preference peer
 */
struct PreferencePeer
{
  /**
   * Next in DLL
   */
  struct PreferencePeer *next;

  /**
   * Previous in DLL
   */
  struct PreferencePeer *prev;

  /**
   * Client
   */
  struct PreferenceClient *client;

  /**
   * Peer id
   */
  struct GNUNET_PeerIdentity id;

  /**
   * Absolute preference values
   */
  double f_abs[GNUNET_ATS_PreferenceCount];

  /**
   * Relative preference values
   */
  double f_rel[GNUNET_ATS_PreferenceCount];

  struct GNUNET_TIME_Absolute next_aging[GNUNET_ATS_PreferenceCount];
};

/**
 * Relative preferences for a peer
 */
struct PeerRelative
{
  /**
   * Relative preference values
   */
  double f_rel[GNUNET_ATS_PreferenceCount];

  /**
   * Peer id
   */
  struct GNUNET_PeerIdentity id;
};

/**
 * Callback to call on changing preference values
 */
static GAS_Normalization_preference_changed_cb pref_changed_cb;

/**
 * Closure for callback to call on changing preference values
 */
static void *pref_changed_cb_cls;

/**
 * Callback to call on changing property values
 */
GAS_Normalization_property_changed_cb prop_ch_cb;

/**
 * Closure for callback to call on changing property values
 */
void *prop_ch_cb_cls;

/**
 * Hashmap to store peer information for preference normalization
 */
static struct GNUNET_CONTAINER_MultiPeerMap *preference_peers;

/**
 * Hashmap to store peer information for property normalization
 * FIXME: this map is not used!
 */
static struct GNUNET_CONTAINER_MultiPeerMap *property_peers;

/**
 * Clients in DLL: head
 */
static struct PreferenceClient *pc_head;

/**
 * Clients in DLL: tail
 */
static struct PreferenceClient *pc_tail;

/**
 * Default values
 */
static struct PeerRelative defvalues;

static GNUNET_SCHEDULER_TaskIdentifier aging_task;

/**
 * Application Preference Normalization
 */

/**
 * Update a peer
 * @param id peer id
 * @param kind the kind
 * @return the new relative preference
 */
static double
update_peers (struct GNUNET_PeerIdentity *id,
    enum GNUNET_ATS_PreferenceKind kind)
{
  struct PreferenceClient *c_cur;
  struct PreferencePeer *p_cur;
  struct PeerRelative *rp;
  double f_rel_total;
  double backup;
  unsigned int count;

  f_rel_total = 0.0;
  count = 0;

  /* For all clients */
  for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
  {
    /* Find peer with id */
    for (p_cur = c_cur->p_head; NULL != p_cur; p_cur = p_cur->next)
    {
      if (0 == memcmp (id, &p_cur->id, sizeof(struct GNUNET_PeerIdentity)))
        break;
    }
    if (NULL != p_cur)
    {
      /* Found peer with id */
      f_rel_total += p_cur->f_rel[kind];
      count++;
    }
  }

  /* Find a client */
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "%u clients have a total relative preference for peer `%s''s `%s' of %.3f\n",
      count, GNUNET_i2s (id), GNUNET_ATS_print_preference_type (kind),
      f_rel_total);
  if (NULL != (rp = GNUNET_CONTAINER_multipeermap_get (preference_peers, id)))
  {
    backup = rp->f_rel[kind];
    if (0 < count)
    {
      rp->f_rel[kind] = f_rel_total / count;
    }
    else
    {
      rp->f_rel[kind] = DEFAULT_REL_PREFERENCE;
    }
  }
  else
  {
    return DEFAULT_REL_PREFERENCE;
  }

  if ((backup != rp->f_rel[kind]) && (NULL != pref_changed_cb))
  {
    pref_changed_cb (pref_changed_cb_cls, &rp->id, kind, rp->f_rel[kind]);
  }

  return rp->f_rel[kind];
}

/**
 * Recalculate preference for a specific ATS property
 *
 * @param c the preference client
 * @param p the peer
 * @param kind the preference kind
 * @return the result
 */
static double
recalculate_rel_preferences (struct PreferenceClient *c,
    struct PreferencePeer *p, enum GNUNET_ATS_PreferenceKind kind)
{
  struct PreferencePeer *p_cur;
  struct PeerRelative *rp;
  double backup;
  double res;
  double ret;

  /* For this client: sum preferences to total preference */
  c->f_abs_sum[kind] = 0;
  for (p_cur = c->p_head; NULL != p_cur; p_cur = p_cur->next)
    c->f_abs_sum[kind] += p_cur->f_abs[kind];
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Client %p has total preference for %s of %.3f\n", c->client,
      GNUNET_ATS_print_preference_type (kind), c->f_abs_sum[kind]);

  ret = DEFAULT_REL_PREFERENCE;
  /* For all peers: calculate relative preference */
  for (p_cur = c->p_head; NULL != p_cur; p_cur = p_cur->next)
  {
    /* Calculate relative preference for specific kind */
    backup = p_cur->f_rel[kind];
    if (DEFAULT_ABS_PREFERENCE == c->f_abs_sum[kind])
      /* No peer has a preference for this property,
       * so set default preference */
      p_cur->f_rel[kind] = DEFAULT_REL_PREFERENCE;
    else
      p_cur->f_rel[kind] = (c->f_abs_sum[kind] + p_cur->f_abs[kind])
          / c->f_abs_sum[kind];

    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
        "Client %p: peer `%s' has relative preference for %s of %.3f\n",
        c->client, GNUNET_i2s (&p_cur->id),
        GNUNET_ATS_print_preference_type (kind), p_cur->f_rel[kind]);

    if (p_cur->f_rel[kind] != backup)
    {
      /* Value changed, recalculate */
      res = update_peers (&p_cur->id, kind);
      if (0 == memcmp (&p->id, &p_cur->id, sizeof(struct GNUNET_PeerIdentity)))
        ret = res;
    }
    else
    {
      /* Value did not chang, return old value*/
      GNUNET_assert(
          NULL != (rp = GNUNET_CONTAINER_multipeermap_get (preference_peers, &p->id)));
      ret = rp->f_rel[kind];
    }
  }
  return ret;
}

/**
 * Update the absolute preference value for a peer
 * @param c the client
 * @param p the peer
 * @param kind the preference kind
 * @param score_abs the absolute value
 * @return the new relative preference value
 */
static double
update_preference (struct PreferenceClient *c, struct PreferencePeer *p,
    enum GNUNET_ATS_PreferenceKind kind, float score_abs)
{
  double score = score_abs;

  /* Update preference value according to type */
  switch (kind)
  {
  case GNUNET_ATS_PREFERENCE_BANDWIDTH:
  case GNUNET_ATS_PREFERENCE_LATENCY:
    p->f_abs[kind] = (p->f_abs[kind] + score) / 2;
    p->next_aging[kind] = GNUNET_TIME_absolute_add (GNUNET_TIME_absolute_get (),
        PREF_AGING_INTERVAL);
    break;
  case GNUNET_ATS_PREFERENCE_END:
    break;
  default:
    break;
  }
  return recalculate_rel_preferences (c, p, kind);
}

/**
 * Reduce absolute preferences since they got old
 *
 * @param cls the PreferencePeer
 * @param tc context
 */
static void
preference_aging (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct PreferencePeer *p;
  struct PreferenceClient *cur_client;
  int i;
  int values_to_update;
  double backup;

  aging_task = GNUNET_SCHEDULER_NO_TASK;
  values_to_update = 0;
  cur_client = NULL;

  for (cur_client = pc_head; NULL != cur_client; cur_client = cur_client->next)
  {
    for (p = cur_client->p_head; NULL != p; p = p->next)
    {
      /* Aging absolute values: */
      for (i = 0; i < GNUNET_ATS_PreferenceCount; i++)
      {
        if (0
            == GNUNET_TIME_absolute_get_remaining (p->next_aging[i]).rel_value_us)
        {
          GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
              "Aging preference for peer `%s'\n", GNUNET_i2s (&p->id));
          backup = p->f_abs[i];
          if (p->f_abs[i] > DEFAULT_ABS_PREFERENCE)
            p->f_abs[i] *= PREF_AGING_FACTOR;
          if (p->f_abs[i] <= DEFAULT_ABS_PREFERENCE + PREF_EPSILON)
            p->f_abs[i] = DEFAULT_ABS_PREFERENCE;
          if ((p->f_abs[i] != DEFAULT_ABS_PREFERENCE)
              && (backup != p->f_abs[i]))
          {
            GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                "Aged preference for peer `%s' from %.3f to %.3f\n",
                GNUNET_i2s (&p->id), backup, p->f_abs[i]);
            recalculate_rel_preferences (p->client, p, i);
            p->next_aging[i] = GNUNET_TIME_absolute_add (
                GNUNET_TIME_absolute_get (), PREF_AGING_INTERVAL);
            values_to_update++;
          }
        }
      }
    }
  }

  if (values_to_update > 0)
  {
    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
        "Rescheduling aging task due to %u elements to age\n",
        values_to_update);
    aging_task = GNUNET_SCHEDULER_add_delayed (PREF_AGING_INTERVAL,
        &preference_aging, NULL );
  }
  else
    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
        "No values to age left, not rescheduling aging task\n");

}

/**
 * Normalize an updated preference value
 *
 * @param src the client with this preference
 * @param peer the peer to change the preference for
 * @param kind the kind to change the preference
 * @param score_abs the normalized score
 */
void
GAS_normalization_normalize_preference (void *src,
    const struct GNUNET_PeerIdentity *peer, enum GNUNET_ATS_PreferenceKind kind,
    float score_abs)
{
  struct PreferenceClient *c_cur;
  struct PreferencePeer *p_cur;
  struct PeerRelative *r_cur;
  int i;

  GNUNET_assert(NULL != src);
  GNUNET_assert(NULL != peer);

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
      "Client %p changes preference for peer `%s' for `%s' to %.2f\n", src,
      GNUNET_i2s (peer), GNUNET_ATS_print_preference_type (kind), score_abs);

  if (kind >= GNUNET_ATS_PreferenceCount)
  {
    GNUNET_break(0);
    return;
  }

  /* Find preference client */
  for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
  {
    if (src == c_cur->client)
      break;
  }
  /* Not found: create new preference client */
  if (NULL == c_cur)
  {
    c_cur = GNUNET_malloc (sizeof (struct PreferenceClient));
    c_cur->client = src;
    GNUNET_CONTAINER_DLL_insert(pc_head, pc_tail, c_cur);
    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Adding new client %p \n", c_cur);
  }

  /* Find entry for peer */
  for (p_cur = c_cur->p_head; NULL != p_cur; p_cur = p_cur->next)
    if (0 == memcmp (&p_cur->id, peer, sizeof(p_cur->id)))
      break;

  /* Not found: create new peer entry */
  if (NULL == p_cur)
  {
    p_cur = GNUNET_malloc (sizeof (struct PreferencePeer));
    p_cur->client = c_cur;
    p_cur->id = (*peer);
    for (i = 0; i < GNUNET_ATS_PreferenceCount; i++)
    {
      /* Default value per peer absolut preference for a quality:
       * No value set, so absolute preference 0 */
      p_cur->f_abs[i] = DEFAULT_ABS_PREFERENCE;
      /* Default value per peer relative preference for a quality: 1.0 */
      p_cur->f_rel[i] = DEFAULT_REL_PREFERENCE;
      p_cur->next_aging[i] = GNUNET_TIME_UNIT_FOREVER_ABS;
    }
    GNUNET_CONTAINER_DLL_insert(c_cur->p_head, c_cur->p_tail, p_cur);
  }

  if (NULL == GNUNET_CONTAINER_multipeermap_get (preference_peers, peer))
  {
    r_cur = GNUNET_new (struct PeerRelative);
    r_cur->id = (*peer);
    for (i = 0; i < GNUNET_ATS_PreferenceCount; i++)
      r_cur->f_rel[i] = DEFAULT_REL_PREFERENCE;
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put (preference_peers, &r_cur->id, r_cur,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  }

  if (GNUNET_SCHEDULER_NO_TASK == aging_task)
    aging_task = GNUNET_SCHEDULER_add_delayed (PREF_AGING_INTERVAL,
        &preference_aging, NULL );

  update_preference (c_cur, p_cur, kind, score_abs);
}

/**
 * Get the normalized preference values for a specific peer or
 * the default values if
 *
 * @param id the peer
 * @return pointer to the values, can be indexed with GNUNET_ATS_PreferenceKind,
 * default preferences if peer does not exist
 */
const double *
GAS_normalization_get_preferences_by_peer (const struct GNUNET_PeerIdentity *id)
{
  GNUNET_assert(NULL != preference_peers);
  GNUNET_assert(NULL != id);

  struct PeerRelative *rp;
  if (NULL == (rp = GNUNET_CONTAINER_multipeermap_get (preference_peers, id)))
  {
    return defvalues.f_rel;
  }
  return rp->f_rel;
}

/**
 * Get the normalized preference values for a specific client and peer
 *
 * @param client client
 * @param peer the peer
 * @param pref the preference type
 * @return the value
 */
const double
GAS_normalization_get_preferences_by_client (const void *client,
    struct GNUNET_PeerIdentity *peer, enum GNUNET_ATS_PreferenceKind pref)
{
  struct PreferenceClient *c_cur;
  struct PreferencePeer *p_cur;

  /* Find preference client */
  for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
  {
    if (client == c_cur->client)
      break;
  }
  if (NULL == c_cur)
    return -1.0;

  for (p_cur = c_cur->p_head; NULL != p_cur; p_cur = p_cur->next)
  {
    if (0 == memcmp (peer, &p_cur->id, sizeof (struct GNUNET_PeerIdentity)))
      break;
  }
  if (NULL == p_cur)
    return DEFAULT_REL_PREFERENCE; /* Not found, return default */

  return p_cur->f_rel[pref];
}

/**
 * Get the normalized properties values for a specific peer or
 * the default values if
 *
 * @param address the address
 * @return pointer to the values, can be indexed with GNUNET_ATS_PreferenceKind,
 * default preferences if peer does not exist
 */
const double *
GAS_normalization_get_properties (struct ATS_Address *address)
{
  static double norm_values[GNUNET_ATS_QualityPropertiesCount];
  int i;

  GNUNET_assert(NULL != address);

  for (i = 0; i < GNUNET_ATS_QualityPropertiesCount; i++)
  {
    if ((address->atsin[i].norm >= 1.0) && (address->atsin[i].norm <= 2.0))
      norm_values[i] = address->atsin[i].norm;
    else
      norm_values[i] = DEFAULT_REL_QUALITY;
  }
  return norm_values;
}

/**
 * Quality Normalization
 */

struct Property
{
  uint32_t prop_type;
  uint32_t atsi_type;
  uint32_t min;
  uint32_t max;
};

struct Property properties[GNUNET_ATS_QualityPropertiesCount];

/**
 * Normalize a specific ATS type with the values in queue
 * @param address the address
 * @param atsi the ats information
 * @return the new average or GNUNET_ATS_VALUE_UNDEFINED
 */

uint32_t
property_average (struct ATS_Address *address,
    const struct GNUNET_ATS_Information *atsi)
{
  struct GAS_NormalizationInfo *ni;
  uint32_t current_type;
  uint32_t current_val;
  uint32_t res;
  uint64_t sum;
  uint32_t count;
  unsigned int c1;
  unsigned int index;
  unsigned int props[] = GNUNET_ATS_QualityProperties;

  /* Average the values of this property */
  current_type = ntohl (atsi->type);
  current_val = ntohl (atsi->value);

  for (c1 = 0; c1 < GNUNET_ATS_QualityPropertiesCount; c1++)
  {
    if (current_type == props[c1])
      break;
  }
  if (c1 == GNUNET_ATS_QualityPropertiesCount)
  {
    GNUNET_break(0);
    return GNUNET_ATS_VALUE_UNDEFINED;
  }
  index = c1;

  ni = &address->atsin[index];
  ni->atsi_abs[ni->avg_queue_index] = current_val;
  ni->avg_queue_index++;
  if (GAS_normalization_queue_length == ni->avg_queue_index)
    ni->avg_queue_index = 0;

  count = 0;
  sum = 0;
  for (c1 = 0; c1 < GAS_normalization_queue_length; c1++)
  {
    if (GNUNET_ATS_VALUE_UNDEFINED != ni->atsi_abs[c1])
    {
      count++;
      if (GNUNET_ATS_VALUE_UNDEFINED > (sum + ni->atsi_abs[c1]))
        sum += ni->atsi_abs[c1];
      else
      {
        sum = GNUNET_ATS_VALUE_UNDEFINED - 1;
        GNUNET_break(0);
      }
    }
  }
  GNUNET_assert(0 != count);
  res = sum / count;
  LOG(GNUNET_ERROR_TYPE_DEBUG,
      "New average of `%s' created by adding %u from %u elements: %u\n",
      GNUNET_ATS_print_property_type (current_type), current_val, count, res,
      sum);
  ni->avg = res;
  return res;
}

struct FindMinMaxCtx
{
  struct Property *p;
  uint32_t min;
  uint32_t max;
};

static int
find_min_max_it (void *cls, const struct GNUNET_PeerIdentity *h, void *k)
{
  struct FindMinMaxCtx *find_res = cls;
  struct ATS_Address *a = k;

  if (a->atsin[find_res->p->prop_type].avg > find_res->max)
    find_res->max = a->atsin[find_res->p->prop_type].avg;

  if (a->atsin[find_res->p->prop_type].avg < find_res->min)
    find_res->min = a->atsin[find_res->p->prop_type].avg;

  return GNUNET_OK;
}

static int
normalize_address (void *cls, const struct GNUNET_PeerIdentity *h, void *k)
{
  struct Property *p = cls;
  struct ATS_Address *address = k;

  double delta;
  uint32_t avg_value = address->atsin[p->prop_type].avg;

  delta = p->max - p->min;
  address->atsin[p->prop_type].norm = (delta + (avg_value - p->min)) / (delta);

  LOG(GNUNET_ERROR_TYPE_DEBUG,
      "Normalize `%s' address %p's '%s' with value %u to range [%u..%u] = %.3f\n",
      GNUNET_i2s (&address->peer), address,
      GNUNET_ATS_print_property_type (p->atsi_type),
      address->atsin[p->prop_type].avg, p->min, p->max,
      address->atsin[p->prop_type].norm);

  if (NULL != prop_ch_cb)
    prop_ch_cb (prop_ch_cb_cls, address, p->atsi_type,
        address->atsin[p->prop_type].norm);

  return GNUNET_OK;
}

/**
 * Normalize avg_value to a range of values between [1.0, 2.0]
 * based on min max values currently known.
 *
 * @param addresses the address hashmap
 * @param p the property
 * @param address the address
 * @param avg_value the value to normalize
 */
static void
property_normalize (struct GNUNET_CONTAINER_MultiPeerMap *addresses,
    struct Property *p, struct ATS_Address *address, uint32_t avg_value)
{
  struct FindMinMaxCtx find_ctx;
  int addr_count;
  int limits_changed;

  find_ctx.p = p;
  find_ctx.max = 0;
  find_ctx.min = UINT32_MAX;
  addr_count = GNUNET_CONTAINER_multipeermap_iterate (addresses,
      &find_min_max_it, &find_ctx);
  if (0 == addr_count)
  {
    GNUNET_break(0);
    return;
  }

  limits_changed = GNUNET_NO;
  if (find_ctx.max != p->max)
  {
    LOG(GNUNET_ERROR_TYPE_DEBUG,
        "Normalizing %s: new maximum %u -> recalculate all values\n",
        GNUNET_ATS_print_property_type (p->atsi_type), find_ctx.max);
    p->max = find_ctx.max;
    limits_changed = GNUNET_YES;
  }

  if ((find_ctx.min != p->min) && (find_ctx.min < p->max))
  {
    LOG(GNUNET_ERROR_TYPE_DEBUG,
        "Normalizing %s: new minimum %u -> recalculate all values\n",
        GNUNET_ATS_print_property_type (p->atsi_type), find_ctx.min,
        find_ctx.max);
    p->min = find_ctx.min;
    limits_changed = GNUNET_YES;
  }
  else if (find_ctx.min == p->max)
  {
    /* Only one value, so minimum has to be 0 */
    p->min = 0;
  }

  /* Normalize the values of this property */
  if (GNUNET_NO == limits_changed)
  {
    /* normalize just this  address */
    normalize_address (p, &address->peer, address);
    return;
  }
  else
  {
    /* limits changed, normalize all addresses */
    GNUNET_CONTAINER_multipeermap_iterate (addresses, &normalize_address, p);
    return;
  }
}

/**
 * Update and normalize atsi performance information
 *
 * @param addresses hashmap containing all addresses
 * @param address the address to update
 * @param atsi the array of performance information
 * @param atsi_count the number of atsi information in the array
 */
void
GAS_normalization_normalize_property (
    struct GNUNET_CONTAINER_MultiPeerMap *addresses,
    struct ATS_Address *address, const struct GNUNET_ATS_Information *atsi,
    uint32_t atsi_count)
{
  struct Property *cur_prop;
  int c1;
  int c2;
  uint32_t current_type;
  uint32_t current_val;
  unsigned int existing_properties[] = GNUNET_ATS_QualityProperties;

  GNUNET_assert(NULL != address);
  GNUNET_assert(NULL != atsi);

  LOG(GNUNET_ERROR_TYPE_DEBUG, "Updating %u elements for peer `%s'\n",
      atsi_count, GNUNET_i2s (&address->peer));

  for (c1 = 0; c1 < atsi_count; c1++)
  {
    current_type = ntohl (atsi[c1].type);

    for (c2 = 0; c2 < GNUNET_ATS_QualityPropertiesCount; c2++)
    {
      /* Check if type is valid */
      if (current_type == existing_properties[c2])
        break;
    }
    if (GNUNET_ATS_QualityPropertiesCount == c2)
    {
      /* Invalid property, continue with next element */
      continue;
    }
    /* Averaging */
    current_val = property_average (address, &atsi[c1]);
    if (GNUNET_ATS_VALUE_UNDEFINED == current_val)
    {
      GNUNET_break(0);
      continue;
    }

    /* Normalizing */
    /* Check min, max */
    cur_prop = &properties[c2];
    property_normalize (addresses, cur_prop, address, current_val);
  }
}

static void
free_client (struct PreferenceClient *pc)
{
  struct PreferencePeer *next_p;
  struct PreferencePeer *p;
  next_p = pc->p_head;
  while (NULL != (p = next_p))
  {
    next_p = p->next;
    GNUNET_CONTAINER_DLL_remove(pc->p_head, pc->p_tail, p);
    GNUNET_free(p);
  }
  GNUNET_free(pc);
}

/**
 * A performance client disconnected
 *
 * @param client the client
 */

void
GAS_normalization_preference_client_disconnect (void *client)
{
  struct PreferenceClient *c_cur;
  /* Find preference client */

  for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
  {
    if (client == c_cur->client)
      break;
  }
  if (NULL == c_cur)
    return;

  GNUNET_CONTAINER_DLL_remove(pc_head, pc_tail, c_cur);
  free_client (c_cur);
}

/**
 * Start the normalization component
 *
 * @param pref_ch_cb callback to call on relative preference changing
 * @param pref_ch_cb_cls cls for the preference callback
 * @param property_ch_cb callback to call on relative property changing
 * @param property_ch_cb_cls cls for the property callback
 */
void
GAS_normalization_start (GAS_Normalization_preference_changed_cb pref_ch_cb,
    void *pref_ch_cb_cls, GAS_Normalization_property_changed_cb property_ch_cb,
    void *property_ch_cb_cls)
{
  int c1;
  int i;
  preference_peers = GNUNET_CONTAINER_multipeermap_create (10, GNUNET_NO);
  property_peers = GNUNET_CONTAINER_multipeermap_create (10, GNUNET_NO);
  unsigned int existing_properties[] = GNUNET_ATS_QualityProperties;

  for (c1 = 0; c1 < GNUNET_ATS_QualityPropertiesCount; c1++)
  {
    properties[c1].prop_type = c1;
    properties[c1].atsi_type = existing_properties[c1];
    properties[c1].min = 0;
    properties[c1].max = 0;
  }

  pref_changed_cb = pref_ch_cb;
  pref_changed_cb_cls = pref_ch_cb_cls;
  prop_ch_cb = property_ch_cb;
  prop_ch_cb_cls = pref_ch_cb_cls;

  pc_head = NULL;
  pc_tail = NULL;

  for (i = 0; i < GNUNET_ATS_PreferenceCount; i++)
    defvalues.f_rel[i] = DEFAULT_REL_PREFERENCE;
  aging_task = GNUNET_SCHEDULER_NO_TASK;
  return;
}

/**
 * Free a peer
 *
 * @param cls unused
 * @param key the key
 * @param value RelativePeer
 * @return #GNUNET_OK to continue
 */
static int
free_peer (void *cls, const struct GNUNET_PeerIdentity *key, void *value)
{
  struct PeerRelative *rp = value;
  if (GNUNET_YES
      == GNUNET_CONTAINER_multipeermap_remove (preference_peers, key, value))
    GNUNET_free(rp);
  else
    GNUNET_break(0);
  return GNUNET_OK;
}

/**
 * Stop the normalization component and free all items
 */
void
GAS_normalization_stop ()
{
  struct PreferenceClient *pc;
  struct PreferenceClient *next_pc;

  if (GNUNET_SCHEDULER_NO_TASK != aging_task)
  {
    GNUNET_SCHEDULER_cancel (aging_task);
    aging_task = GNUNET_SCHEDULER_NO_TASK;
  }

  next_pc = pc_head;
  while (NULL != (pc = next_pc))
  {
    next_pc = pc->next;
    GNUNET_CONTAINER_DLL_remove(pc_head, pc_tail, pc);
    free_client (pc);
  }

  GNUNET_CONTAINER_multipeermap_iterate (preference_peers, &free_peer, NULL );
  GNUNET_CONTAINER_multipeermap_destroy (preference_peers);
  GNUNET_CONTAINER_multipeermap_destroy (property_peers);
  return;
}

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