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path: root/src/dht/gnunet_dht_profiler.c
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/*
     This file is part of GNUnet.
     Copyright (C) 2014 GNUnet e.V.

     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., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/

/**
 * @file dht/gnunet_dht_profiler.c
 * @brief Profiler for GNUnet DHT
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_testbed_service.h"
#include "gnunet_dht_service.h"

#define INFO(...)                                       \
  GNUNET_log (GNUNET_ERROR_TYPE_INFO, __VA_ARGS__)

#define DEBUG(...)                                           \
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, __VA_ARGS__)

/**
 * Number of peers which should perform a PUT out of 100 peers
 */
#define PUT_PROBABILITY 50

/**
 * Configuration
 */
static struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * Name of the file with the hosts to run the test over
 */
static char *hosts_file;

/**
 * Context for a peer which actively does DHT PUT/GET
 */
struct ActiveContext;

/**
 * Context to hold data of peer
 */
struct Context
{
  /**
   * The testbed peer this context belongs to
   */
  struct GNUNET_TESTBED_Peer *peer;

  /**
   * Testbed operation acting on this peer
   */
  struct GNUNET_TESTBED_Operation *op;

  /**
   * Active context; NULL if this peer is not an active peer
   */
  struct ActiveContext *ac;

};


/**
 * Context for a peer which actively does DHT PUT/GET
 */
struct ActiveContext
{
  /**
   * The linked peer context
   */
  struct Context *ctx;

  /**
   * Handler to the DHT service
   */
  struct GNUNET_DHT_Handle *dht;

  /**
   * The data used for do a PUT.  Will be NULL if a PUT hasn't been performed yet
   */
  void *put_data;

  /**
   * The active context used for our DHT GET
   */
  struct ActiveContext *get_ac;

  /**
   * The put handle
   */
  struct GNUNET_DHT_PutHandle *dht_put;

  /**
   * The get handle
   */
  struct GNUNET_DHT_GetHandle *dht_get;

  /**
   * The hash of the @e put_data
   */
  struct GNUNET_HashCode hash;

  /**
   * Delay task
   */
  struct GNUNET_SCHEDULER_Task * delay_task;

  /**
   * The size of the @e put_data
   */
  uint16_t put_data_size;

  /**
   * The number of peers currently doing GET on our data
   */
  uint16_t nrefs;
};


/**
 * An array of contexts.  The size of this array should be equal to @a num_peers
 */
static struct Context *a_ctx;

/**
 * Array of active peers
 */
static struct ActiveContext *a_ac;

/**
 * The delay between rounds for collecting statistics
 */
static struct GNUNET_TIME_Relative delay_stats;

/**
 * The delay to start puts.
 */
static struct GNUNET_TIME_Relative delay_put;

/**
 * The delay to start puts.
 */
static struct GNUNET_TIME_Relative delay_get;

/**
 * The timeout for GET and PUT
 */
static struct GNUNET_TIME_Relative timeout;

/**
 * Number of peers
 */
static unsigned int num_peers;

/**
 * Number of active peers
 */
static unsigned int n_active;

/**
 * Number of DHT service connections we currently have
 */
static unsigned int n_dht;

/**
 * Number of DHT PUTs made
 */
static unsigned int n_puts;

/**
 * Number of DHT PUTs succeeded
 */
static unsigned int n_puts_ok;

/**
 * Number of DHT PUTs failed
 */
static unsigned int n_puts_fail;

/**
 * Number of DHT GETs made
 */
static unsigned int n_gets;

/**
 * Number of DHT GETs succeeded
 */
static unsigned int n_gets_ok;

/**
 * Number of DHT GETs succeeded
 */
static unsigned int n_gets_fail;

/**
 * Replication degree
 */
static unsigned int replication;

/**
 * Number of times we try to find the successor circle formation
 */
static unsigned int max_searches;

/**
 * Testbed Operation (to get stats).
 */
static struct GNUNET_TESTBED_Operation *bandwidth_stats_op;

/**
 * To get successor stats.
 */
static struct GNUNET_TESTBED_Operation *successor_stats_op;

/**
 * Testbed peer handles.
 */
static struct GNUNET_TESTBED_Peer **testbed_handles;

/**
 * Total number of messages sent by peer.
 */
static uint64_t outgoing_bandwidth;

/**
 * Total number of messages received by peer.
 */
static uint64_t incoming_bandwidth;

/**
 * Average number of hops taken to do put.
 */
static double average_put_path_length;

/**
 * Average number of hops taken to do get.
 */
static double average_get_path_length;

/**
 * Total put path length across all peers.
 */
static unsigned int total_put_path_length;

/**
 * Total get path length across all peers.
 */
static unsigned int total_get_path_length;

/**
 * Hashmap to store pair of peer and its corresponding successor.
 */
static struct GNUNET_CONTAINER_MultiHashMap *successor_peer_hashmap;

/**
 * Key to start the lookup on successor_peer_hashmap.
 */
static struct GNUNET_HashCode *start_key;

/**
 * Flag used to get the start_key.
 */
static int flag = 0;

/**
 * Task to collect peer and its current successor statistics.
 */
static struct GNUNET_SCHEDULER_Task * successor_stats_task;

/**
 * Closure for successor_stats_task.
 */
struct Collect_Stat_Context
{
  /**
   * Current Peer Context.
   */
  struct Context *service_connect_ctx;

  /**
   * Testbed operation acting on this peer
   */
  struct GNUNET_TESTBED_Operation *op;
};

/**
 * List of all the peers contexts.
 */
struct Context **peer_contexts = NULL;

/**
 * Counter to keep track of peers added to peer_context lists.
 */
static int peers_started = 0;

/**
 * Should we do a PUT (mode = 0) or GET (mode = 1);
 */
static enum
{
  MODE_PUT = 0,

  MODE_GET = 1
} mode;


/**
 * Are we shutting down
 */
static int in_shutdown = 0;

/**
 * Total number of times to check if circle is formed or not.
 */
static unsigned int tries;


/**
 * Task that collects successor statistics from all the peers.
 *
 * @param cls
 */
static void
collect_stats (void *cls);


/**
 * Connect to DHT services of active peers
 */
static void
start_profiling (void);


/**
 * Shutdown task.  Cleanup all resources and operations.
 *
 * @param cls NULL
 */
static void
do_shutdown (void *cls)
{
  struct ActiveContext *ac;
  unsigned int cnt;

  in_shutdown = GNUNET_YES;
  if (NULL != a_ctx)
  {
    for (cnt=0; cnt < num_peers; cnt++)
    {
      /* Cleanup active context if this peer is an active peer */
      ac = a_ctx[cnt].ac;
      if (NULL != ac)
      {
        if (NULL != ac->delay_task)
          GNUNET_SCHEDULER_cancel (ac->delay_task);
        if (NULL != ac->put_data)
          GNUNET_free (ac->put_data);
        if (NULL != ac->dht_put)
          GNUNET_DHT_put_cancel (ac->dht_put);
        if (NULL != ac->dht_get)
          GNUNET_DHT_get_stop (ac->dht_get);
      }
      /* Cleanup testbed operation handle at the last as this operation may
         contain service connection to DHT */
      if (NULL != a_ctx[cnt].op)
        GNUNET_TESTBED_operation_done (a_ctx[cnt].op);
    }
    GNUNET_free (a_ctx);
    a_ctx = NULL;
  }
  //FIXME: Should we collect stats only for put/get not for other messages.
  if (NULL != bandwidth_stats_op)
  {
    GNUNET_TESTBED_operation_done (bandwidth_stats_op);
    bandwidth_stats_op = NULL;
  }
  if (NULL != successor_stats_op)
  {
    GNUNET_TESTBED_operation_done (successor_stats_op);
    successor_stats_op = NULL;
  }
  if (NULL != successor_stats_task)
  {
    GNUNET_SCHEDULER_cancel (successor_stats_task);
    successor_stats_task = NULL;
  }
  GNUNET_free_non_null (a_ac);
}


/**
 * Stats callback. Finish the stats testbed operation and when all stats have
 * been iterated, shutdown the test.
 *
 * @param cls closure
 * @param op the operation that has been finished
 * @param emsg error message in case the operation has failed; will be NULL if
 *          operation has executed successfully.
 */
static void
bandwidth_stats_cont (void *cls,
                      struct GNUNET_TESTBED_Operation *op,
                      const char *emsg)
{
  INFO ("# Outgoing bandwidth: %llu\n",
        (unsigned long long) outgoing_bandwidth);
  INFO ("# Incoming bandwidth: %llu\n",
        (unsigned long long) incoming_bandwidth);
  GNUNET_SCHEDULER_shutdown ();
}


/**
 * Process statistic values.
 *
 * @param cls closure
 * @param peer the peer the statistic belong to
 * @param subsystem name of subsystem that created the statistic
 * @param name the name of the datum
 * @param value the current value
 * @param is_persistent #GNUNET_YES if the value is persistent, #GNUNET_NO if not
 * @return #GNUNET_OK to continue, #GNUNET_SYSERR to abort iteration
 */
static int
bandwidth_stats_iterator (void *cls,
                          const struct GNUNET_TESTBED_Peer *peer,
                          const char *subsystem,
                          const char *name,
                          uint64_t value,
                          int is_persistent)
{
   static const char *s_sent = "# Bytes transmitted to other peers";
   static const char *s_recv = "# Bytes received from other peers";

   if (0 == strncmp (s_sent, name, strlen (s_sent)))
     outgoing_bandwidth = outgoing_bandwidth + value;
   else if (0 == strncmp(s_recv, name, strlen (s_recv)))
     incoming_bandwidth = incoming_bandwidth + value;

    return GNUNET_OK;
}


static void
summarize ()
{
  INFO ("# PUTS made: %u\n", n_puts);
  INFO ("# PUTS succeeded: %u\n", n_puts_ok);
  INFO ("# PUTS failed: %u\n", n_puts_fail);
  INFO ("# GETS made: %u\n", n_gets);
  INFO ("# GETS succeeded: %u\n", n_gets_ok);
  INFO ("# GETS failed: %u\n", n_gets_fail);
  INFO ("# average_put_path_length: %f\n", average_put_path_length);
  INFO ("# average_get_path_length: %f\n", average_get_path_length);

  if (NULL == testbed_handles)
  {
    INFO ("No peers found\n");
    return;
  }
  /* Collect Stats*/
  bandwidth_stats_op = GNUNET_TESTBED_get_statistics (n_active, testbed_handles,
                                                      "dht", NULL,
                                                       bandwidth_stats_iterator,
                                                       bandwidth_stats_cont, NULL);
}


/**
 * Task to cancel DHT GET.
 *
 * @param cls NULL
 */
static void
cancel_get (void *cls)
{
  struct ActiveContext *ac = cls;
  struct Context *ctx = ac->ctx;

  ac->delay_task = NULL;
  GNUNET_assert (NULL != ac->dht_get);
  GNUNET_DHT_get_stop (ac->dht_get);
  ac->dht_get = NULL;
  n_gets_fail++;
  GNUNET_assert (NULL != ctx->op);
  GNUNET_TESTBED_operation_done (ctx->op);
  ctx->op = NULL;

  /* If profiling is complete, summarize */
  if (n_active == n_gets_fail + n_gets_ok)
  {
    average_put_path_length = (double)total_put_path_length/(double)n_active;
    average_get_path_length = (double)total_get_path_length/(double )n_gets_ok;
    summarize ();
  }
}


/**
 * Iterator called on each result obtained for a DHT
 * operation that expects a reply
 *
 * @param cls closure
 * @param exp when will this value expire
 * @param key key of the result
 * @param get_path peers on reply path (or NULL if not recorded)
 *                 [0] = datastore's first neighbor, [length - 1] = local peer
 * @param get_path_length number of entries in @a get_path
 * @param put_path peers on the PUT path (or NULL if not recorded)
 *                 [0] = origin, [length - 1] = datastore
 * @param put_path_length number of entries in @a put_path
 * @param type type of the result
 * @param size number of bytes in @a data
 * @param data pointer to the result data
 */
static void
get_iter (void *cls,
          struct GNUNET_TIME_Absolute exp,
          const struct GNUNET_HashCode *key,
          const struct GNUNET_PeerIdentity *get_path,
          unsigned int get_path_length,
          const struct GNUNET_PeerIdentity *put_path,
          unsigned int put_path_length,
          enum GNUNET_BLOCK_Type type,
          size_t size, const void *data)
{
  struct ActiveContext *ac = cls;
  struct ActiveContext *get_ac = ac->get_ac;
  struct Context *ctx = ac->ctx;

  /* Check the keys of put and get match or not. */
  GNUNET_assert (0 == memcmp (key, &get_ac->hash, sizeof (struct GNUNET_HashCode)));
  /* we found the data we are looking for */
  DEBUG ("We found a GET request; %u remaining\n", n_gets - (n_gets_fail + n_gets_ok)); //FIXME: It always prints 1.
  n_gets_ok++;
  get_ac->nrefs--;
  GNUNET_DHT_get_stop (ac->dht_get);
  ac->dht_get = NULL;
  if (ac->delay_task != NULL)
    GNUNET_SCHEDULER_cancel (ac->delay_task);
  ac->delay_task = NULL;
  GNUNET_assert (NULL != ctx->op);
  GNUNET_TESTBED_operation_done (ctx->op);
  ctx->op = NULL;

  total_put_path_length = total_put_path_length + (double)put_path_length;
  total_get_path_length = total_get_path_length + (double)get_path_length;
  DEBUG ("total_put_path_length = %u,put_path \n",
         total_put_path_length);
  /* Summarize if profiling is complete */
  if (n_active == n_gets_fail + n_gets_ok)
  {
    average_put_path_length = (double)total_put_path_length/(double)n_active;
    average_get_path_length = (double)total_get_path_length/(double )n_gets_ok;
    summarize ();
  }
}


/**
 * Task to do DHT GETs
 *
 * @param cls the active context
 */
static void
delayed_get (void *cls)
{
  struct ActiveContext *ac = cls;
  struct ActiveContext *get_ac;
  unsigned int r;

  ac->delay_task = NULL;
  get_ac = NULL;
  while (1)
  {
    r = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, n_active);
    get_ac = &a_ac[r];
    if (NULL != get_ac->put_data)
      break;
  }
  get_ac->nrefs++;
  ac->get_ac = get_ac;
  DEBUG ("GET_REQUEST_START key %s \n", GNUNET_h2s((struct GNUNET_HashCode *)ac->put_data));
  ac->dht_get = GNUNET_DHT_get_start (ac->dht,
                                      GNUNET_BLOCK_TYPE_TEST,
                                      &get_ac->hash,
                                      1, /* replication level */
                                      GNUNET_DHT_RO_NONE,
                                      NULL, 0, /* extended query and size */
                                      get_iter, ac); /* GET iterator and closure
                                                        */
  n_gets++;

  /* schedule the timeout task for GET */
  ac->delay_task = GNUNET_SCHEDULER_add_delayed (timeout, &cancel_get, ac);
}


/**
 * Task to teardown the dht connection.  We do it as a task because calling
 * GNUNET_DHT_disconnect() from put_continutation_callback seems illegal (the
 * put_continuation_callback() is getting called again synchronously).  Also,
 * only free the operation when we are not shutting down; the shutdown task will
 * clear the operation during shutdown.
 *
 * @param cls the context
 */
static void
teardown_dht_connection (void *cls)
{
  struct Context *ctx = cls;
  struct GNUNET_TESTBED_Operation *op;

  GNUNET_assert (NULL != ctx);
  GNUNET_assert (NULL != (op = ctx->op));
  ctx->op = NULL;
  GNUNET_TESTBED_operation_done (op);
}


/**
 * Queue up a delayed task for doing DHT GET
 *
 * @param cls the active context
 * @param success #GNUNET_OK if the PUT was transmitted,
 *                #GNUNET_NO on timeout,
 *                #GNUNET_SYSERR on disconnect from service
 *                after the PUT message was transmitted
 *                (so we don't know if it was received or not)
 */
static void
put_cont (void *cls, int success)
{
  struct ActiveContext *ac = cls;
  struct Context *ctx = ac->ctx;

  ac->dht_put = NULL;
  if (success)
    n_puts_ok++;
  else
    n_puts_fail++;
  GNUNET_assert (NULL != ctx);
  (void) GNUNET_SCHEDULER_add_now (&teardown_dht_connection, ctx);
}


/**
 * Task to do DHT PUTs
 *
 * @param cls the active context
 */
static void
delayed_put (void *cls)
{
  struct ActiveContext *ac = cls;

  ac->delay_task = NULL;
  /* Generate and DHT PUT some random data */
  ac->put_data_size = 16;       /* minimum */
  ac->put_data_size += GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
                                                 (63*1024));
  ac->put_data = GNUNET_malloc (ac->put_data_size);
  GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_WEAK,
                              ac->put_data, ac->put_data_size);
  GNUNET_CRYPTO_hash (ac->put_data, ac->put_data_size, &ac->hash);
  DEBUG ("PUT_REQUEST_START key %s\n",
         GNUNET_h2s((struct GNUNET_HashCode *)ac->put_data));
  ac->dht_put = GNUNET_DHT_put (ac->dht,
                                &ac->hash,
                                replication,
                                GNUNET_DHT_RO_RECORD_ROUTE,
                                GNUNET_BLOCK_TYPE_TEST,
                                ac->put_data_size,
                                ac->put_data,
                                GNUNET_TIME_UNIT_FOREVER_ABS, /* expiration time */
                                &put_cont, ac);                /* continuation and its closure */
  n_puts++;
}


/**
 * Connection to DHT has been established.  Call the delay task.
 *
 * @param cls the active context
 * @param op the operation that has been finished
 * @param ca_result the service handle returned from GNUNET_TESTBED_ConnectAdapter()
 * @param emsg error message in case the operation has failed; will be NULL if
 *          operation has executed successfully.
 */
static void
dht_connected (void *cls,
               struct GNUNET_TESTBED_Operation *op,
               void *ca_result,
               const char *emsg)
{
  struct ActiveContext *ac = cls;
  struct Context *ctx = ac->ctx;

  GNUNET_assert (NULL != ctx); //FIXME: Fails
  GNUNET_assert (NULL != ctx->op);
  GNUNET_assert (ctx->op == op);
  ac->dht = (struct GNUNET_DHT_Handle *) ca_result;
  if (NULL != emsg)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Connection to DHT service failed: %s\n", emsg);
    GNUNET_TESTBED_operation_done (ctx->op); /* Calls dht_disconnect() */
    ctx->op = NULL;
    return;
  }
  switch (mode)
  {
  case MODE_PUT:
  {
    struct GNUNET_TIME_Relative peer_delay_put;
    peer_delay_put.rel_value_us =
      GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK,
                                delay_put.rel_value_us);
    ac->delay_task = GNUNET_SCHEDULER_add_delayed (peer_delay_put, &delayed_put, ac);
    break;
  }
  case MODE_GET:
  {
    struct GNUNET_TIME_Relative peer_delay_get;
    peer_delay_get.rel_value_us =
      delay_get.rel_value_us +
      GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK,
                                delay_get.rel_value_us);
    ac->delay_task = GNUNET_SCHEDULER_add_delayed (peer_delay_get, &delayed_get, ac);
    break;
  }
  }
}


/**
 * Connect to DHT service and return the DHT client handler
 *
 * @param cls the active context
 * @param cfg configuration of the peer to connect to; will be available until
 *          GNUNET_TESTBED_operation_done() is called on the operation returned
 *          from GNUNET_TESTBED_service_connect()
 * @return service handle to return in 'op_result', NULL on error
 */
static void *
dht_connect (void *cls, const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  n_dht++;
  return GNUNET_DHT_connect (cfg, 10);
}


/**
 * Adapter function called to destroy a connection to
 * a service.
 *
 * @param cls the active context
 * @param op_result service handle returned from the connect adapter
 */
static void
dht_disconnect (void *cls, void *op_result)
{
  struct ActiveContext *ac = cls;

  GNUNET_assert (NULL != ac->dht);
  GNUNET_assert (ac->dht == op_result);
  GNUNET_DHT_disconnect (ac->dht);
  ac->dht = NULL;
  n_dht--;
  if (0 != n_dht)
    return;
  if (GNUNET_YES == in_shutdown)
    return;
  switch (mode)
  {
  case MODE_PUT:
    if ((n_puts_ok + n_puts_fail) != n_active)
      return;
    /* Start GETs if all PUTs have been made */
    mode = MODE_GET;
    //(void) GNUNET_SCHEDULER_add_now (&call_start_profiling, NULL);
    start_profiling ();
    return;
  case MODE_GET:
    if ((n_gets_ok + n_gets_fail) != n_active)
      return;
    break;
  }
}

/**
 * Connect to DHT services of active peers
 */
static void
start_profiling()
{
  struct Context *ctx;
  unsigned int i;

  DEBUG("GNUNET_TESTBED_service_connect \n");
  GNUNET_break (GNUNET_YES != in_shutdown);
  for(i = 0; i < n_active; i++)
  {
    struct ActiveContext *ac = &a_ac[i];
    GNUNET_assert (NULL != (ctx = ac->ctx));
    GNUNET_assert (NULL == ctx->op);
    ctx->op =
        GNUNET_TESTBED_service_connect (ctx,
                                        ctx->peer,
                                        "dht",
                                        &dht_connected, ac,
                                        &dht_connect,
                                        &dht_disconnect,
                                        ac);
  }
}

/**
 * Start collecting relevant statistics. If ENABLE_MALICIOUS set, first
 * set the malicious peers. If not, then start with PUT operation on active
 * peers.
 */
static void
start_func()
{
  start_profiling();
}


/**
 * Remove entry from successor peer hashmap.
 * @param cls closure
 * @param key current public key
 * @param value value in the hash map
 * @return #GNUNET_YES if we should continue to iterate,
 *         #GNUNET_NO if not.
 */
static int
hashmap_iterate_remove(void *cls,
                       const struct GNUNET_HashCode *key,
                       void *value)
{
  GNUNET_assert (GNUNET_YES ==
                GNUNET_CONTAINER_multihashmap_remove(successor_peer_hashmap, key, value));
  return GNUNET_YES;
}


/**
 * Stats callback. Iterate over the hashmap and check if all th peers form
 * a virtual ring topology.
 *
 * @param cls closure
 * @param op the operation that has been finished
 * @param emsg error message in case the operation has failed; will be NULL if
 *          operation has executed successfully.
 */
static void
successor_stats_cont (void *cls,
                      struct GNUNET_TESTBED_Operation *op,
                      const char *emsg)
{
  struct GNUNET_HashCode *val;
  struct GNUNET_HashCode *start_val;
  struct GNUNET_HashCode *key;
  int count;

  /* Don't schedule the task till we are looking for circle here. */
  successor_stats_task = NULL;
  GNUNET_TESTBED_operation_done (successor_stats_op);
  successor_stats_op = NULL;
  if (0 == max_searches)
  {
    start_func ();
    return;
  }

  GNUNET_assert (NULL != start_key);
  start_val = GNUNET_CONTAINER_multihashmap_get (successor_peer_hashmap,
                                                 start_key);
  GNUNET_assert (NULL != start_val);
  val = start_val;
  for (count = 0; count < num_peers; count++)
  {
    key = val;
    val = GNUNET_CONTAINER_multihashmap_get (successor_peer_hashmap,
                                             key);
    if (NULL == val)
      break;
    /* Remove the entry from hashmap. This is done to take care of loop. */
    if (GNUNET_NO ==
        GNUNET_CONTAINER_multihashmap_remove (successor_peer_hashmap,
                                              key, val))
    {
      DEBUG ("Failed to remove entry from hashmap\n");
      break;
    }
    /* If a peer has its own identity as its successor. */
    if (0 == memcmp(key, val, sizeof (struct GNUNET_HashCode)))
      break;
  }

  GNUNET_assert (GNUNET_SYSERR !=
                 GNUNET_CONTAINER_multihashmap_iterate (successor_peer_hashmap,
                                                        &hashmap_iterate_remove,
                                                        NULL));

  successor_peer_hashmap = GNUNET_CONTAINER_multihashmap_create (num_peers,
                                                                 GNUNET_NO);
  if ((start_val == val) && (count == num_peers))
  {
    DEBUG ("CIRCLE COMPLETED after %u tries", tries);
    if(NULL == successor_stats_task)
    {
      start_func();
    }
    return;
  }
  if (max_searches == ++tries)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		"Maximum tries %u exceeded while checking successor TOTAL TRIES %u"
		" circle formation.  Exiting\n",
		max_searches,tries);
    start_func();
    return;
  }
  flag = 0;
  successor_stats_task
    = GNUNET_SCHEDULER_add_delayed (delay_stats,
				    &collect_stats,
				    cls);
}


/**
 * Process successor statistic values.
 *
 * @param cls closure
 * @param peer the peer the statistic belong to
 * @param subsystem name of subsystem that created the statistic
 * @param name the name of the datum
 * @param value the current value
 * @param is_persistent GNUNET_YES if the value is persistent, GNUNET_NO if not
 * @return GNUNET_OK to continue, GNUNET_SYSERR to abort iteration
 */
static int
successor_stats_iterator (void *cls,
                          const struct GNUNET_TESTBED_Peer *peer,
                          const char *subsystem,
                          const char *name,
                          uint64_t value,
                          int is_persistent)
{
  static const char *key_string = "XDHT";
  if (0 == max_searches)
    return GNUNET_OK;

  if (0 == strncmp (key_string, name, strlen (key_string)))
  {
    char *my_id_str;
    char successor_str[13];
    char truncated_my_id_str[13];
    char truncated_successor_str[13];
    struct GNUNET_HashCode *my_id_key;
    struct GNUNET_HashCode *succ_key;

    strtok((char *)name,":");
    my_id_str = strtok(NULL,":");

    strncpy(truncated_my_id_str, my_id_str, 12);
    truncated_my_id_str[12] = '\0';
    my_id_key = GNUNET_new(struct GNUNET_HashCode);
    GNUNET_CRYPTO_hash (truncated_my_id_str, sizeof(truncated_my_id_str),my_id_key);
    GNUNET_STRINGS_data_to_string(&value, sizeof(uint64_t), successor_str, 13);
    strncpy(truncated_successor_str, successor_str, 12);
    truncated_successor_str[12] ='\0';

    succ_key = GNUNET_new(struct GNUNET_HashCode);
    GNUNET_CRYPTO_hash (truncated_successor_str, sizeof(truncated_successor_str),succ_key);

    if (0 == flag)
    {
      GNUNET_assert(NULL != my_id_key);
      start_key = my_id_key;
      GNUNET_assert(NULL != start_key);
      flag = 1;
    }
    GNUNET_CONTAINER_multihashmap_put (successor_peer_hashmap,
                                       my_id_key, (void *)succ_key,
                                       GNUNET_CONTAINER_MULTIHASHMAPOPTION_REPLACE);
  }

  return GNUNET_OK;
}


/*
 * Task that collects peer and its corresponding successors.
 *
 * @param cls Closure (NULL).
 */
static void
collect_stats (void *cls)
{
  successor_stats_task = NULL;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Start collecting statistics...\n");
  GNUNET_assert(NULL != testbed_handles);

  if (0 != max_searches)
    successor_peer_hashmap
      = GNUNET_CONTAINER_multihashmap_create (num_peers,
					      GNUNET_NO);
  successor_stats_op
    = GNUNET_TESTBED_get_statistics (num_peers, testbed_handles,
				     "dht", NULL,
				     successor_stats_iterator,
				     successor_stats_cont, cls);
  GNUNET_assert (NULL != successor_stats_op);
}


/**
 * Callback called when DHT service on the peer is started
 *
 * @param cls the context
 * @param op the operation that has been finished
 * @param emsg error message in case the operation has failed; will be NULL if
 *          operation has executed successfully.
 */
static void
service_started (void *cls,
                 struct GNUNET_TESTBED_Operation *op,
                 const char *emsg)
{
  struct Context *ctx = cls;

  GNUNET_assert (NULL != ctx);
  GNUNET_assert (NULL != ctx->op);
  GNUNET_TESTBED_operation_done (ctx->op);
  ctx->op = NULL;
  peers_started++;
  DEBUG("Peers Started = %d; num_peers = %d \n", peers_started, num_peers);
  if (NULL == successor_stats_task && peers_started == num_peers)
  {
     DEBUG("successor_stats_task \n");
     struct Collect_Stat_Context *collect_stat_cls = GNUNET_new(struct Collect_Stat_Context);
     collect_stat_cls->service_connect_ctx = cls;
     collect_stat_cls->op = op;

     successor_stats_task
       = GNUNET_SCHEDULER_add_delayed (delay_stats,
				       &collect_stats,
				       collect_stat_cls);
  }
}


/**
 * Signature of a main function for a testcase.
 *
 * @param cls closure
 * @param h the run handle
 * @param num_peers number of peers in 'peers'
 * @param peers handle to peers run in the testbed
 * @param links_succeeded the number of overlay link connection attempts that
 *          succeeded
 * @param links_failed the number of overlay link
 */
static void
test_run (void *cls,
          struct GNUNET_TESTBED_RunHandle *h,
          unsigned int num_peers, struct GNUNET_TESTBED_Peer **peers,
          unsigned int links_succeeded,
          unsigned int links_failed)
{
  unsigned int cnt;
  unsigned int ac_cnt;
  testbed_handles = peers;
  if (NULL == peers)
  {
    /* exit */
    GNUNET_assert (0);
  }
  INFO ("%u peers started\n", num_peers);
  a_ctx = GNUNET_malloc (sizeof (struct Context) * num_peers);

  /* select the peers which actively participate in profiling */
  n_active = num_peers * PUT_PROBABILITY / 100;
  if (0 == n_active)
  {
    GNUNET_SCHEDULER_shutdown ();
    GNUNET_free (a_ctx);
    return;
  }

  a_ac = GNUNET_malloc (n_active * sizeof (struct ActiveContext));
  ac_cnt = 0;
  for (cnt = 0; cnt < num_peers && ac_cnt < n_active; cnt++)
  {
    if ((GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 100) >=
        PUT_PROBABILITY))
      continue;

    a_ctx[cnt].ac = &a_ac[ac_cnt];
    a_ac[ac_cnt].ctx = &a_ctx[cnt];
    ac_cnt++;
  }
  n_active = ac_cnt;
  INFO ("Active peers: %u\n", n_active);

  /* start DHT service on all peers */
  for (cnt = 0; cnt < num_peers; cnt++)
  {
    a_ctx[cnt].peer = peers[cnt];
    a_ctx[cnt].op = GNUNET_TESTBED_peer_manage_service (&a_ctx[cnt],
                                                        peers[cnt],
                                                        "dht",
                                                        &service_started,
                                                        &a_ctx[cnt],
                                                        1);
  }
}


/**
 * Main function that will be run by the scheduler.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param config configuration
 */
static void
run (void *cls, char *const *args, const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *config)
{
  uint64_t event_mask;

  if (0 == num_peers)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("Exiting as the number of peers is %u\n"),
                num_peers);
    return;
  }
  cfg = GNUNET_CONFIGURATION_dup (config);
  event_mask = 0;
  GNUNET_TESTBED_run (hosts_file, cfg, num_peers, event_mask, NULL,
                      NULL, &test_run, NULL);
  GNUNET_SCHEDULER_add_shutdown (&do_shutdown,
				 NULL);
}


/**
 * Main function.
 *
 * @return 0 on success
 */
int
main (int argc, char *const *argv)
{
  int rc;

  struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_option_uint ('n',
                                   "peers",
                                   "COUNT",
                                   gettext_noop ("number of peers to start"),
                                   &num_peers),

    GNUNET_GETOPT_option_uint ('s',
                                   "searches",
                                   "COUNT",
                                   gettext_noop ("maximum number of times we try to search for successor circle formation (0 for R5N)"),
                                   &max_searches),

    GNUNET_GETOPT_option_string ('H',
                                 "hosts",
                                 "FILENAME",
                                 gettext_noop ("name of the file with the login information for the testbed"),
                                 &hosts_file),

    GNUNET_GETOPT_option_relative_time ('D',
                                            "delay",
                                            "DELAY",
                                            gettext_noop ("delay between rounds for collecting statistics (default: 30 sec)"),
                                            &delay_stats),

    GNUNET_GETOPT_option_relative_time ('P',
                                            "PUT-delay",
                                            "DELAY",
                                            gettext_noop ("delay to start doing PUTs (default: 1 sec)"),
                                            &delay_put),

    GNUNET_GETOPT_option_relative_time ('G',
                                            "GET-delay",
                                            "DELAY",
                                            gettext_noop ("delay to start doing GETs (default: 5 min)"),
                                            &delay_get),
    GNUNET_GETOPT_option_uint ('r',
                                   "replication",
                                   "DEGREE",
                                   gettext_noop ("replication degree for DHT PUTs"),
                                   &replication),


    GNUNET_GETOPT_option_relative_time ('t',
                                            "timeout",
                                            "TIMEOUT",
                                            gettext_noop ("timeout for DHT PUT and GET requests (default: 1 min)"),
                                            &timeout),
    GNUNET_GETOPT_OPTION_END
  };

  max_searches = 5;
  if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
    return 2;
  /* set default delays */
  delay_stats = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10);
  delay_put = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10);
  delay_get = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10);
  timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10);
  replication = 1;      /* default replication */
  rc = 0;
  if (GNUNET_OK !=
      GNUNET_PROGRAM_run (argc, argv, "dht-profiler",
			  gettext_noop
			  ("Measure quality and performance of the DHT service."),
			  options, &run, NULL))
    rc = 1;
  return rc;
}