moved sampler functionality in file of its own

1 files changed, 677 insertions, 0 deletions

diff --git a/src/rps/gnunet-service-rps_sampler.c b/src/rps/gnunet-service-rps_sampler.c
new file mode 100644
index 000000000..f80a70108
--- /dev/null
+++ b/src/rps/gnunet-service-rps_sampler.c
@@ -0,0 +1,677 @@
+/*
+     This file is part of GNUnet.
+     (C)
+
+     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 rps/gnunet-service-rps_sampler.c
+ * @brief sampler implementation
+ * @author Julius Bünger
+ */
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "rps.h"
+
+#include "gnunet-service-rps_sampler.h"
+
+#include <math.h>
+#include <inttypes.h>
+
+#define LOG(kind, ...) GNUNET_log(kind, __VA_ARGS__)
+
+// multiple 'clients'?
+
+// TODO check for overflows
+
+// TODO align message structs
+
+// hist_size_init, hist_size_max
+
+/***********************************************************************
+ * WARNING: This section needs to be reviewed regarding the use of
+ * functions providing (pseudo)randomness!
+***********************************************************************/
+
+// TODO care about invalid input of the caller (size 0 or less...)
+
+enum RPS_SamplerEmpty
+{
+  NOT_EMPTY = 0x0,
+      EMPTY = 0x1
+};
+
+/**
+ * A sampler element sampling one PeerID at a time.
+ */
+struct RPS_SamplerElement
+{
+  /**
+   * Min-wise linear permutation used by this sampler.
+   *
+   * This is an key later used by a hmac.
+   */
+  struct GNUNET_CRYPTO_AuthKey auth_key;
+
+  /**
+   * The PeerID this sampler currently samples.
+   */
+  struct GNUNET_PeerIdentity peer_id;
+
+  /**
+   * The according hash value of this PeerID.
+   */
+  struct GNUNET_HashCode peer_id_hash;
+
+  /**
+   * Time of last request.
+   */
+  struct GNUNET_TIME_Absolute last_request;
+  
+  /**
+   * Flag that indicates that we are not holding a valid PeerID right now.
+   */
+  enum RPS_SamplerEmpty is_empty;
+};
+
+/**
+ * Sampler with its own array of SamplerElements
+ */
+struct RPS_Sampler
+{
+  /**
+   * Number of sampler elements we hold.
+   */
+  unsigned int sampler_size;
+  //size_t size;
+
+  /**
+   * All Samplers in one array.
+   */
+  struct RPS_SamplerElement **sampler_elements;
+
+  /**
+   * Index to a sampler element.
+   *
+   * Gets cycled on every hist_request.
+   */
+  uint64_t sampler_elem_index;
+
+  /**
+   * Callback to be called when a peer gets inserted into a sampler.
+   */
+  RPS_sampler_insert_cb insert_cb;
+
+  /**
+   * Closure to the insert_cb.
+   */
+  void *insert_cls;
+
+  /**
+   * Callback to be called when a peer gets inserted into a sampler.
+   */
+  RPS_sampler_remove_cb remove_cb;
+
+  /**
+   * Closure to the remove_cb.
+   */
+  void *remove_cls;
+};
+
+/**
+ * Global sampler variable.
+ */
+struct RPS_Sampler *sampler;
+
+
+/**
+ * The minimal size for the extended sampler elements.
+ */
+static size_t min_size;
+
+/**
+ * The maximal size the extended sampler elements should grow to.
+ */
+static size_t max_size;
+
+/**
+ * The size the extended sampler elements currently have.
+ */
+static size_t extra_size;
+
+/**
+ * Inedex to the sampler element that is the next to be returned
+ */
+static struct RPS_SamplerElement **extended_samplers_index;
+
+/**
+ * Request counter.
+ *
+ * Only needed in the beginning to check how many of the 64 deltas
+ * we already have
+ */
+static unsigned int req_counter;
+
+/**
+ * Time of the last request we received.
+ *
+ * Used to compute the expected request rate.
+ */
+static struct GNUNET_TIME_Absolute last_request;
+
+/**
+ * Last 64 deltas between requests
+ */
+static struct GNUNET_TIME_Relative request_deltas[64];
+
+/**
+ * The prediction of the rate of requests
+ */
+static struct GNUNET_TIME_Relative  request_rate;
+
+
+/**
+ * Sum all time relatives of an array.
+ */
+  struct GNUNET_TIME_Relative
+T_relative_sum (const struct GNUNET_TIME_Relative *rel_array, uint64_t arr_size)
+{
+  struct GNUNET_TIME_Relative sum;
+  uint64_t i;
+
+  sum = GNUNET_TIME_UNIT_ZERO;
+  for ( i = 0 ; i < arr_size ; i++ )
+  {
+    sum = GNUNET_TIME_relative_add (sum, rel_array[i]);
+  }
+  return sum;
+}
+
+/**
+ * Compute the average of given time relatives.
+ */
+  struct GNUNET_TIME_Relative
+T_relative_avg (const struct GNUNET_TIME_Relative *rel_array, uint64_t arr_size)
+{
+  return T_relative_sum (rel_array, arr_size); // FIXME find a way to devide that by arr_size
+}
+
+
+
+/**
+ * Reinitialise a previously initialised sampler element.
+ *
+ * @param sampler pointer to the memory that keeps the value.
+ */
+  static void
+RPS_sampler_elem_reinit (struct RPS_SamplerElement *sampler_el)
+{
+  sampler_el->is_empty = EMPTY;
+
+  // I guess I don't need to call GNUNET_CRYPTO_hmac_derive_key()...
+  GNUNET_CRYPTO_random_block(GNUNET_CRYPTO_QUALITY_STRONG,
+                             &(sampler_el->auth_key.key),
+                             GNUNET_CRYPTO_HASH_LENGTH);
+
+  sampler_el->last_request = GNUNET_TIME_UNIT_FOREVER_ABS;
+
+  /* We might want to keep the previous peer */
+
+  //GNUNET_CRYPTO_hmac(&sampler_el->auth_key, sampler_el->peer_id,
+  //                   sizeof(struct GNUNET_PeerIdentity),
+  //                   &sampler_el->peer_id_hash);
+}
+
+
+/**
+ * (Re)Initialise given Sampler with random min-wise independent function.
+ *
+ * In this implementation this means choosing an auth_key for later use in
+ * a hmac at random.
+ *
+ * @return a newly created RPS_SamplerElement which currently holds no id.
+ */
+  struct RPS_SamplerElement *
+RPS_sampler_elem_create (void)
+{
+  struct RPS_SamplerElement *s;
+  
+  s = GNUNET_new (struct RPS_SamplerElement);
+
+  RPS_sampler_elem_reinit (s);
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: initialised with empty PeerID\n");
+
+  return s;
+}
+
+
+/**
+ * Input an PeerID into the given sampler.
+ */
+  static void
+RPS_sampler_elem_next (struct RPS_SamplerElement *s_elem, const struct GNUNET_PeerIdentity *other,
+    RPS_sampler_insert_cb insert_cb, void *insert_cls,
+    RPS_sampler_remove_cb remove_cb, void *remove_cls)
+{
+  struct GNUNET_HashCode other_hash;
+
+  if ( 0 == GNUNET_CRYPTO_cmp_peer_identity(other, &(s_elem->peer_id)) )
+  {
+    LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER:          Got PeerID %s_elem\n",
+        GNUNET_i2s(other));
+    LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Have already PeerID %s_elem\n",
+        GNUNET_i2s(&(s_elem->peer_id)));
+  }
+  else
+  {
+    GNUNET_CRYPTO_hmac(&s_elem->auth_key,
+        other,
+        sizeof(struct GNUNET_PeerIdentity),
+        &other_hash);
+
+    if ( EMPTY == s_elem->is_empty )
+    { // Or whatever is a valid way to say
+      // "we have no PeerID at the moment"
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Got PeerID %s_elem; Simply accepting (was empty previously).\n",
+          GNUNET_i2s(other));
+      s_elem->peer_id = *other;
+      //s_elem->peer_id = other;
+      s_elem->peer_id_hash = other_hash;
+      if (NULL != sampler->insert_cb)
+      {
+        sampler->insert_cb(sampler->insert_cls, &(s_elem->peer_id));
+      }
+    }
+    else if ( 0 > GNUNET_CRYPTO_hash_cmp(&other_hash, &s_elem->peer_id_hash) )
+    {
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER:            Got PeerID %s_elem\n",
+          GNUNET_i2s(other));
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Discarding old PeerID %s_elem\n",
+          GNUNET_i2s(&s_elem->peer_id));
+
+      if ( NULL != sampler->remove_cb )
+      {
+        LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Removing old PeerID %s_elem with the remove callback.\n",
+            GNUNET_i2s(&s_elem->peer_id));
+        sampler->remove_cb(sampler->remove_cls, &s_elem->peer_id);
+      }
+
+      memcpy(&s_elem->peer_id, other, sizeof(struct GNUNET_PeerIdentity));
+      //s_elem->peer_id = other;
+      s_elem->peer_id_hash = other_hash;
+
+      if ( NULL != sampler->insert_cb )
+      {
+        LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Inserting new PeerID %s_elem with the insert callback.\n",
+            GNUNET_i2s(&s_elem->peer_id));
+        sampler->insert_cb(sampler->insert_cls, &s_elem->peer_id);
+      }
+    }
+    else
+    {
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER:         Got PeerID %s_elem\n",
+          GNUNET_i2s(other));
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Keeping old PeerID %s_elem\n",
+          GNUNET_i2s(&s_elem->peer_id));
+    }
+  }
+  s_elem->is_empty = NOT_EMPTY;
+}
+
+
+/**
+ * Grow or shrink the size of the sampler.
+ *
+ * @param new_size the new size of the sampler
+ */
+  void
+RPS_sampler_resize (unsigned int new_size)
+{
+  unsigned int old_size;
+  uint64_t i;
+  struct RPS_SamplerElement **rem_list;
+
+  // TODO check min and max size
+
+  old_size = sampler->sampler_size;
+
+  if (old_size > new_size*4 &&
+      extra_size > new_size*4)
+  { /* Shrinking */
+
+    new_size /= 2;
+
+    /* Temporary store those to properly call the removeCB on those later */
+    rem_list = GNUNET_malloc ((old_size - new_size) * sizeof (struct RPS_SamplerElement *));
+    memcpy (rem_list,
+        &sampler->sampler_elements[new_size],
+        (old_size - new_size) * sizeof(struct RPS_SamplerElement *));
+
+    LOG (GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Shrinking sampler %d -> %d\n", old_size, new_size);
+    GNUNET_array_grow (sampler->sampler_elements, sampler->sampler_size, new_size);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+        "SAMPLER: sampler->sampler_elements now points to %p\n",
+        sampler->sampler_elements);
+
+    // TODO move extended_samplers_index
+    for (i = new_size ; i < old_size ; i++)
+    {/* Remove unneeded rest */
+      LOG (GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Removing %" PRIX64 ". sampler\n", i);
+      if (NULL != sampler->remove_cb)
+        sampler->remove_cb (sampler->remove_cls, &rem_list[i]->peer_id);
+      GNUNET_free (rem_list[i]);
+    }
+  }
+  else if (old_size < new_size)// ||
+      //extra_size < new_size) // needed?
+  { /* Growing */
+    new_size *= 2; // TODO check overflow
+
+    LOG (GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Growing sampler %d -> %d\n", old_size, new_size);
+    GNUNET_array_grow (sampler->sampler_elements, sampler->sampler_size, new_size);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+        "SAMPLER: sampler->sampler_elements now points to %p\n",
+        sampler->sampler_elements);
+
+    // TODO move extended_samplers_index
+
+    for ( i = old_size ; i < new_size ; i++ )
+    { /* Add new sampler elements */
+      sampler->sampler_elements[i] = RPS_sampler_elem_create ();
+      if (NULL != sampler->insert_cb)
+        sampler->insert_cb (sampler->insert_cls, &sampler->sampler_elements[i]->peer_id);
+      LOG (GNUNET_ERROR_TYPE_DEBUG,
+          "SAMPLER: Added %" PRIX64 ". sampler, now pointing to %p, contains %s\n",
+          i, &sampler->sampler_elements[i], GNUNET_i2s (&sampler->sampler_elements[i]->peer_id));
+    }
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Size remains the same -- nothing to do\n");
+    return;
+  }
+
+  GNUNET_assert(sampler->sampler_size == new_size);
+  LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Finished growing/shrinking.\n"); // remove
+}
+
+
+/**
+ * Initialise a tuple of sampler elements.
+ *
+ * @param init_size the size the sampler is initialised with
+ * @param id with which all newly created sampler elements are initialised
+ * @param ins_cb the callback that will be called on every PeerID that is 
+ *               newly inserted into a sampler element
+ * @param ins_cls the closure given to #ins_cb
+ * @param rem_cb the callback that will be called on every PeerID that is
+ *               removed from a sampler element
+ * @param rem_cls the closure given to #rem_cb
+ */
+  void
+RPS_sampler_init (size_t init_size, const struct GNUNET_PeerIdentity *id,
+    RPS_sampler_insert_cb ins_cb, void *ins_cls,
+    RPS_sampler_remove_cb rem_cb, void *rem_cls)
+{
+  //struct RPS_Sampler *sampler;
+  //uint64_t i;
+
+  /* Initialise context around extended sampler */
+  min_size = 10; // TODO make input to _samplers_init()
+  max_size = 1000; // TODO make input to _samplers_init()
+  GNUNET_new_array (64, struct GNUNET_TIME_Relative);
+
+  sampler = GNUNET_new (struct RPS_Sampler);
+  sampler->sampler_size = 0;
+  sampler->sampler_elements = NULL;
+  sampler->insert_cb = ins_cb;
+  sampler->insert_cls = ins_cls;
+  sampler->remove_cb = rem_cb;
+  sampler->remove_cls = rem_cls;
+  //sampler->sampler_elements = GNUNET_new_array(init_size, struct GNUNET_PeerIdentity);
+  //GNUNET_array_grow (sampler->sampler_elements, sampler->sampler_size, min_size);
+  RPS_sampler_resize (init_size);
+  RPS_sampler_update_list (id); // no super nice desing but ok for the moment
+
+  extended_samplers_index = sampler->sampler_elements;
+
+  //GNUNET_assert (init_size == sampler->sampler_size);
+}
+
+
+/**
+ * A fuction to update every sampler in the given list
+ *
+ * @param id the PeerID that is put in the sampler
+ */
+  void
+RPS_sampler_update_list (const struct GNUNET_PeerIdentity *id)
+{
+  uint64_t i;
+
+  for ( i = 0 ; i < sampler->sampler_size ; i++ )
+    RPS_sampler_elem_next (sampler->sampler_elements[i], id,
+        sampler->insert_cb, sampler->insert_cls,
+        sampler->remove_cb, sampler->remove_cls);
+}
+
+
+/**
+ * Reinitialise all previously initialised sampler elements with the given value.
+ *
+ * Used to get rid of a PeerID.
+ *
+ * @param id the id of the sampler elements to update.
+ */
+  void
+RPS_sampler_reinitialise_by_value (const struct GNUNET_PeerIdentity *id)
+{
+  uint64_t i;
+
+  for ( i = 0 ; i < sampler->sampler_size ; i++ )
+  {
+    if ( 0 == GNUNET_CRYPTO_cmp_peer_identity(id, &(sampler->sampler_elements[i]->peer_id)) )
+    {
+      LOG(GNUNET_ERROR_TYPE_DEBUG, "SAMPLER: Reinitialising sampler\n");
+      RPS_sampler_elem_reinit (sampler->sampler_elements[i]);
+    }
+  }
+}
+
+
+/**
+ * Get one random peer out of the sampled peers.
+ *
+ * We might want to reinitialise this sampler after giving the
+ * corrsponding peer to the client.
+ * Only used internally
+ */
+  const struct GNUNET_PeerIdentity * 
+RPS_sampler_get_rand_peer_ ()
+{
+  uint64_t r_index;
+  const struct GNUNET_PeerIdentity *peer; // do we have to malloc that?
+
+  // TODO implement extra logic
+
+  /**;
+   * Choose the r_index of the peer we want to return
+   * at random from the interval of the gossip list
+   */
+  r_index = GNUNET_CRYPTO_random_u64(GNUNET_CRYPTO_QUALITY_STRONG,
+      sampler->sampler_size);
+
+  //if ( EMPTY == sampler->sampler_elements[r_index]->is_empty )
+  //  // TODO schedule for later
+  //  peer = NULL;
+  //else
+    peer = &(sampler->sampler_elements[r_index]->peer_id);
+  sampler->sampler_elements[r_index]->last_request = GNUNET_TIME_absolute_get();
+  LOG(GNUNET_ERROR_TYPE_DEBUG, "Sgrp: Returning PeerID %s\n", GNUNET_i2s(peer));
+
+
+  return peer;
+}
+
+/**
+ * Get n random peers out of the sampled peers.
+ *
+ * We might want to reinitialise this sampler after giving the
+ * corrsponding peer to the client.
+ * Random with or without consumption?
+ * Only used internally
+ */
+  const struct GNUNET_PeerIdentity *
+RPS_sampler_get_n_rand_peers_ (uint64_t n)
+{
+  if ( 0 == sampler->sampler_size )
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+        "Sgrp: List empty - Returning NULL\n");
+    return NULL;
+  }
+  else
+  {
+    // TODO check if we have too much (distinct) sampled peers
+    // If we are not ready yet maybe schedule for later
+    struct GNUNET_PeerIdentity *peers;
+    uint64_t i;
+
+    peers = GNUNET_malloc (n * sizeof(struct GNUNET_PeerIdentity));
+
+    for ( i = 0 ; i < n ; i++ ) {
+      //peers[i] = RPS_sampler_get_rand_peer_(sampler->sampler_elements);
+      memcpy (&peers[i], RPS_sampler_get_rand_peer_ (), sizeof (struct GNUNET_PeerIdentity));
+    }
+    return peers;
+  }
+}
+
+
+/**
+ * Get one random peer out of the sampled peers.
+ *
+ * We might want to reinitialise this sampler after giving the
+ * corrsponding peer to the client.
+ *
+ * @return a random PeerID of the PeerIDs previously put into the sampler.
+ */
+  const struct GNUNET_PeerIdentity * 
+RPS_sampler_get_rand_peer ()
+{
+  struct GNUNET_PeerIdentity *peer;
+
+  if (64 > req_counter)
+    req_counter++;
+  if (1 < req_counter)
+  {
+    memcpy (&request_deltas[1],
+        request_deltas,
+        (req_counter - 1) * sizeof (struct GNUNET_TIME_Relative));
+    request_deltas[0] = GNUNET_TIME_absolute_get_difference (last_request,
+        GNUNET_TIME_absolute_get ());
+    request_rate = T_relative_avg (request_deltas, req_counter);
+  }
+  last_request = GNUNET_TIME_absolute_get();
+  // TODO resize the size of the extended_samplers
+
+  // use _get_rand_peer_ ?
+  peer = GNUNET_new (struct GNUNET_PeerIdentity);
+  *peer = (*extended_samplers_index)->peer_id;
+  RPS_sampler_elem_reinit (*extended_samplers_index);
+  if ( extended_samplers_index == &sampler->sampler_elements[sampler->sampler_size -1] )
+    extended_samplers_index = &sampler->sampler_elements[0];
+  else
+    extended_samplers_index++;
+  // TODO
+  return peer;
+}
+
+
+/**
+ * Get n random peers out of the sampled peers.
+ *
+ * We might want to reinitialise this sampler after giving the
+ * corrsponding peer to the client.
+ * Random with or without consumption?
+ *
+ * @return n random PeerIDs of the PeerIDs previously put into the sampler.
+ */
+  const struct GNUNET_PeerIdentity *
+RPS_sampler_get_n_rand_peers (uint64_t n)
+{
+  // use _get_rand_peers_ ?
+  if ( 0 == sampler->sampler_size )
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+        "Sgrp: List empty - Returning NULL\n");
+    return NULL;
+  }
+  else
+  {
+    // TODO check if we have too much (distinct) sampled peers
+    // If we are not ready yet maybe schedule for later
+    struct GNUNET_PeerIdentity *peers;
+    uint64_t i;
+
+    peers = GNUNET_malloc (n * sizeof(struct GNUNET_PeerIdentity));
+
+    for ( i = 0 ; i < n ; i++ ) {
+      //peers[i] = RPS_sampler_get_rand_peer_(sampler->sampler_elements);
+      memcpy (&peers[i], RPS_sampler_get_rand_peer (), sizeof (struct GNUNET_PeerIdentity));
+    }
+    return peers;
+  }
+}
+
+
+/**
+ * Counts how many Samplers currently hold a given PeerID.
+ *
+ * @param id the PeerID to count.
+ *
+ * @return the number of occurrences of id.
+ */
+  uint64_t
+RPS_sampler_count_id (const struct GNUNET_PeerIdentity *id)
+{
+  uint64_t count;
+  uint64_t i;
+
+  count = 0;
+  for ( i = 0 ; i < sampler->sampler_size ; i++ )
+  {
+    if ( 0 == GNUNET_CRYPTO_cmp_peer_identity (&sampler->sampler_elements[i]->peer_id, id) 
+        && EMPTY != sampler->sampler_elements[i]->is_empty)
+      count++;
+  }
+  return count;
+}
+
+
+/**
+ * Cleans the sampler.
+ */
+  void
+RPS_sampler_destroy ()
+{
+  RPS_sampler_resize (0);
+  GNUNET_free (request_deltas); // _array_grow()?
+  GNUNET_array_grow (sampler->sampler_elements, sampler->sampler_size, 0);
+}
+
+/* end of gnunet-service-rps.c */