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21 * @file ats/gnunet-service-ats_preferences.c
22 * @brief manage preferences expressed by clients
23 * @author Matthias Wachs
24 * @author Christian Grothoff
27 #include "gnunet-service-ats.h"
28 #include "gnunet-service-ats_addresses.h"
29 #include "gnunet-service-ats_performance.h"
30 #include "gnunet-service-ats_plugins.h"
31 #include "gnunet-service-ats_preferences.h"
32 #include "gnunet-service-ats_reservations.h"
35 #define LOG(kind,...) GNUNET_log_from (kind, "ats-preferences",__VA_ARGS__)
38 * How frequently do we age preference values?
40 #define PREF_AGING_INTERVAL GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
43 * By which factor do we age preferences expressed during
44 * each #PREF_AGING_INTERVAL?
46 #define PREF_AGING_FACTOR 0.95
49 * What is the lowest threshold up to which prefernce values
50 * are aged, and below which we consider them zero and thus
51 * no longer subject to aging?
53 #define PREF_EPSILON 0.01
57 * Relative preferences for a peer.
62 * Array of relative preference values, to be indexed by
63 * an `enum GNUNET_ATS_PreferenceKind`.
65 double f_rel[GNUNET_ATS_PREFERENCE_END];
68 * Number of clients that are expressing a preference for
69 * this peer. When this counter reaches zero, this entry
72 unsigned int num_clients;
77 * Default values, returned as our preferences if we do not
78 * have any preferences expressed for a peer.
80 static struct PeerRelative defvalues;
84 * Preference information per peer and client.
89 * Next in DLL of preference entries for the same client.
91 struct PreferencePeer *next;
94 * Previous in DLL of preference entries for the same client.
96 struct PreferencePeer *prev;
99 * Absolute preference values for all preference types
100 * as expressed by this client for this peer.
102 double f_abs[GNUNET_ATS_PREFERENCE_END];
105 * Relative preference values for all preference types,
106 * normalized in [0..1] based on how the respective
107 * client scored other peers.
109 double f_rel[GNUNET_ATS_PREFERENCE_END];
115 * Preference client, as in a client that expressed preferences
116 * for peers. This is the information we keep track of for each
119 struct PreferenceClient
123 * Next in client list
125 struct PreferenceClient *next;
128 * Previous in client peer list
130 struct PreferenceClient *prev;
135 struct GNUNET_SERVICE_Client *client;
138 * Mapping peer identities to `struct PreferencePeer` entry
139 * for the respective peer.
141 struct GNUNET_CONTAINER_MultiPeerMap *peer2pref;
144 * Array of sums of absolute preferences for all
145 * peers as expressed by this client.
147 double f_abs_sum[GNUNET_ATS_PREFERENCE_END];
153 * Hashmap to store peer information for preference normalization.
154 * Maps the identity of a peer to a `struct PeerRelative` containing
155 * the current relative preference values for that peer.
157 static struct GNUNET_CONTAINER_MultiPeerMap *preference_peers;
160 * Clients in DLL: head
162 static struct PreferenceClient *pc_head;
165 * Clients in DLL: tail
167 static struct PreferenceClient *pc_tail;
170 * Handle for task we run periodically to age preferences over time.
172 static struct GNUNET_SCHEDULER_Task *aging_task;
176 * Closure for #sum_relative_preferences().
181 * Where to accumulate the result.
186 * Which kind of preference value are we adding up?
188 enum GNUNET_ATS_PreferenceKind kind;
193 * Add the relative preference for the kind given to the
196 * @param cls the `struct SumContext` with the kind and place
197 * to store the result
198 * @param peer ignored
199 * @param value the `struct PreferencePeer` for getting the rel pref.
203 sum_relative_preferences (void *cls,
204 const struct GNUNET_PeerIdentity *peer,
207 struct SumContext *sum_ctx = cls;
208 struct PreferencePeer *p_cur = value;
210 sum_ctx->f_rel_total += p_cur->f_rel[sum_ctx->kind];
216 * Update the total releative preference for a peer by summing
217 * up the relative preferences all clients have for this peer.
219 * @param id peer id of the peer for which we should do the update
220 * @param kind the kind of preference value to update
221 * @return the new relative preference
224 update_relative_values_for_peer (const struct GNUNET_PeerIdentity *id,
225 enum GNUNET_ATS_PreferenceKind kind)
227 struct PreferenceClient *c_cur;
228 struct SumContext sum_ctx;
229 struct PeerRelative *rp;
231 sum_ctx.f_rel_total = 0.0;
233 for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
234 GNUNET_CONTAINER_multipeermap_get_multiple (c_cur->peer2pref,
236 &sum_relative_preferences,
238 LOG (GNUNET_ERROR_TYPE_DEBUG,
239 "Total relative preference for peer `%s' for `%s' is %.3f\n",
241 GNUNET_ATS_print_preference_type (kind),
242 sum_ctx.f_rel_total);
243 rp = GNUNET_CONTAINER_multipeermap_get (preference_peers,
245 GNUNET_assert (NULL != rp);
246 if (rp->f_rel[kind] != sum_ctx.f_rel_total)
248 rp->f_rel[kind] = sum_ctx.f_rel_total;
249 GAS_plugin_notify_preference_changed (id,
257 * Free a peer's `struct PeerRelative`.
261 * @param value the `struct PeerRelative` to free.
262 * @return #GNUNET_OK to continue
265 free_peer (void *cls,
266 const struct GNUNET_PeerIdentity *key,
269 struct PeerRelative *rp = value;
271 GNUNET_assert (GNUNET_YES ==
272 GNUNET_CONTAINER_multipeermap_remove (preference_peers,
281 * Free `struct PreferencePeer` entry in map.
283 * @param cls the `struct PreferenceClient` with the map
284 * @param key the peer the entry is for
285 * @param value the `struct PreferencePeer` entry to free
286 * @return #GNUNET_OK (continue to iterate)
289 free_preference (void *cls,
290 const struct GNUNET_PeerIdentity *key,
293 struct PreferenceClient *pc = cls;
294 struct PreferencePeer *p = value;
295 struct PeerRelative *pr;
297 GNUNET_assert (GNUNET_OK ==
298 GNUNET_CONTAINER_multipeermap_remove (pc->peer2pref,
302 pr = GNUNET_CONTAINER_multipeermap_get (preference_peers,
304 GNUNET_assert (NULL != pr);
305 GNUNET_assert (pr->num_clients > 0);
307 if (0 == pr->num_clients)
318 * Closure for #age_values().
323 * Counter of values remaining to update, incremented for each value
324 * changed (to a new non-zero value).
326 unsigned int values_to_update;
329 * Client we are currently aging values for.
331 struct PreferenceClient *cur_client;
337 * Age preference values of the given peer.
340 * @param peer peer being aged
341 * @param value the `struct PreferencePeer` for the peer
342 * @return #GNUNET_OK (continue to iterate)
345 age_values (void *cls,
346 const struct GNUNET_PeerIdentity *peer,
349 struct AgeContext *ac = cls;
350 struct PreferencePeer *p = value;
355 for (i = 0; i < GNUNET_ATS_PREFERENCE_END; i++)
357 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
358 "Aging preference for peer `%s'\n",
360 if (p->f_abs[i] > DEFAULT_ABS_PREFERENCE)
361 p->f_abs[i] *= PREF_AGING_FACTOR;
362 if (p->f_abs[i] <= DEFAULT_ABS_PREFERENCE + PREF_EPSILON)
364 p->f_abs[i] = DEFAULT_ABS_PREFERENCE;
365 p->f_rel[i] = DEFAULT_REL_PREFERENCE;
366 update_relative_values_for_peer (peer,
371 ac->values_to_update++;
375 if (GNUNET_YES == dead)
377 /* all preferences are zero, remove this entry */
378 free_preference (ac->cur_client,
387 * Reduce absolute preferences since they got old.
392 preference_aging (void *cls)
394 struct AgeContext ac;
397 GAS_plugin_solver_lock ();
398 ac.values_to_update = 0;
399 for (ac.cur_client = pc_head; NULL != ac.cur_client; ac.cur_client = ac.cur_client->next)
400 GNUNET_CONTAINER_multipeermap_iterate (ac.cur_client->peer2pref,
403 GAS_plugin_solver_unlock ();
404 if (ac.values_to_update > 0)
406 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
407 "Rescheduling aging task due to %u elements remaining to age\n",
408 ac.values_to_update);
409 if (NULL == aging_task)
410 aging_task = GNUNET_SCHEDULER_add_delayed (PREF_AGING_INTERVAL,
416 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
417 "No values to age left, not rescheduling aging task\n");
423 * Closure for #update_rel_sum() and #update_abs_sum().
428 * Preference client with the sum of all absolute scores.
430 struct PreferenceClient *pc;
433 * Which kind are we updating?
435 enum GNUNET_ATS_PreferenceKind kind;
441 * Compute updated absolute score for the client based on the
442 * current absolute scores for each peer.
444 * @param cls a `struct UpdateContext`
445 * @param peer peer being updated
446 * @param value the `struct PreferencePeer` for the peer
447 * @return #GNUNET_OK (continue to iterate)
450 update_abs_sum (void *cls,
451 const struct GNUNET_PeerIdentity *peer,
454 struct UpdateContext *uc = cls;
455 struct PreferencePeer *p_cur = value;
457 uc->pc->f_abs_sum[uc->kind] += p_cur->f_abs[uc->kind];
463 * Compute updated relative score for each peer based on the
464 * current absolute score given by this client.
466 * @param cls a `struct UpdateContext`
467 * @param peer peer being updated
468 * @param value the `struct PreferencePeer` for the peer (updated)
469 * @return #GNUNET_OK (continue to iterate)
472 update_rel_sum (void *cls,
473 const struct GNUNET_PeerIdentity *peer,
476 struct UpdateContext *uc = cls;
477 struct PreferencePeer *p_cur = value;
479 p_cur->f_rel[uc->kind] = p_cur->f_abs[uc->kind] / uc->pc->f_abs_sum[uc->kind];
480 LOG (GNUNET_ERROR_TYPE_DEBUG,
481 "Client has relative preference for %s for peer `%s' of %.3f\n",
482 GNUNET_ATS_print_preference_type (uc->kind),
484 p_cur->f_rel[uc->kind]);
490 * Recalculate preference for a specific ATS property
492 * @param c the preference client
493 * @param kind the preference kind
497 recalculate_relative_preferences (struct PreferenceClient *c,
498 enum GNUNET_ATS_PreferenceKind kind)
500 struct UpdateContext uc;
502 /* For this client: sum of absolute preference values for this preference */
505 c->f_abs_sum[kind] = 0.0;
507 /* For all peers: calculate sum of absolute preferences */
508 GNUNET_CONTAINER_multipeermap_iterate (c->peer2pref,
511 LOG (GNUNET_ERROR_TYPE_DEBUG,
512 "Client has sum of total preferences for %s of %.3f\n",
513 GNUNET_ATS_print_preference_type (kind),
516 /* For all peers: calculate relative preference */
517 GNUNET_CONTAINER_multipeermap_iterate (c->peer2pref,
524 * The relative preferences of one of the clients have
525 * changed, update the global preferences for the given
526 * peer and notify the plugin.
528 * @param cls the kind of preference to calculate the
529 * new global relative preference values for
530 * @param key the peer to update relative preference values for
531 * @param value a `struct PeerRelative`, unused
534 update_iterator (void *cls,
535 const struct GNUNET_PeerIdentity *key,
538 enum GNUNET_ATS_PreferenceKind *kind = cls;
540 update_relative_values_for_peer (key,
547 * Update the absolute preference and calculate the
548 * new relative preference value.
550 * @param client the client with this preference
551 * @param peer the peer to change the preference for
552 * @param kind the kind to change the preference
553 * @param score_abs the normalized score
556 update_preference (struct GNUNET_SERVICE_Client *client,
557 const struct GNUNET_PeerIdentity *peer,
558 enum GNUNET_ATS_PreferenceKind kind,
561 struct PreferenceClient *c_cur;
562 struct PreferencePeer *p_cur;
563 struct PeerRelative *r_cur;
566 if (kind >= GNUNET_ATS_PREFERENCE_END)
571 LOG (GNUNET_ERROR_TYPE_DEBUG,
572 "Client changes preference for peer `%s' for `%s' to %.2f\n",
574 GNUNET_ATS_print_preference_type (kind),
577 /* Find preference client */
578 for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
579 if (client == c_cur->client)
581 /* Not found: create new preference client */
584 c_cur = GNUNET_new (struct PreferenceClient);
585 c_cur->client = client;
586 c_cur->peer2pref = GNUNET_CONTAINER_multipeermap_create (16,
588 for (i = 0; i < GNUNET_ATS_PREFERENCE_END; i++)
589 c_cur->f_abs_sum[i] = DEFAULT_ABS_PREFERENCE;
590 GNUNET_CONTAINER_DLL_insert (pc_head,
595 /* check global peer entry exists */
597 (r_cur = GNUNET_CONTAINER_multipeermap_get (preference_peers,
600 /* Create struct for peer */
601 r_cur = GNUNET_new (struct PeerRelative);
602 for (i = 0; i < GNUNET_ATS_PREFERENCE_END; i++)
603 r_cur->f_rel[i] = DEFAULT_REL_PREFERENCE;
604 GNUNET_assert (GNUNET_OK ==
605 GNUNET_CONTAINER_multipeermap_put (preference_peers,
608 GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
611 /* Find entry for peer */
612 p_cur = GNUNET_CONTAINER_multipeermap_get (c_cur->peer2pref,
616 /* Not found: create new peer entry */
617 p_cur = GNUNET_new (struct PreferencePeer);
618 for (i = 0; i < GNUNET_ATS_PREFERENCE_END; i++)
620 /* Default value per peer absolute preference for a preference*/
621 p_cur->f_abs[i] = DEFAULT_ABS_PREFERENCE;
622 /* Default value per peer relative preference for a quality */
623 p_cur->f_rel[i] = DEFAULT_REL_PREFERENCE;
625 GNUNET_assert (GNUNET_YES ==
626 GNUNET_CONTAINER_multipeermap_put (c_cur->peer2pref,
629 GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
630 r_cur->num_clients++;
633 p_cur->f_abs[kind] += score_abs;
634 recalculate_relative_preferences (c_cur, kind);
635 GNUNET_CONTAINER_multipeermap_iterate (preference_peers,
639 if (NULL == aging_task)
640 aging_task = GNUNET_SCHEDULER_add_delayed (PREF_AGING_INTERVAL,
647 * Handle 'preference change' messages from clients.
649 * @param client the client that sent the request
650 * @param msg the request message
653 GAS_handle_preference_change (struct GNUNET_SERVICE_Client *client,
654 const struct ChangePreferenceMessage *msg)
656 const struct PreferenceInformation *pi;
659 nump = ntohl (msg->num_preferences);
660 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
661 "Received PREFERENCE_CHANGE message for peer `%s'\n",
662 GNUNET_i2s (&msg->peer));
663 GNUNET_STATISTICS_update (GSA_stats,
664 "# preference change requests processed",
667 pi = (const struct PreferenceInformation *) &msg[1];
668 GAS_plugin_solver_lock ();
669 for (uint32_t i = 0; i < nump; i++)
670 update_preference (client,
672 (enum GNUNET_ATS_PreferenceKind) ntohl (pi[i].preference_kind),
673 pi[i].preference_value);
674 GAS_plugin_solver_unlock ();
679 * Initialize preferences subsystem.
682 GAS_preference_init ()
686 preference_peers = GNUNET_CONTAINER_multipeermap_create (16,
688 for (i = 0; i < GNUNET_ATS_PREFERENCE_END; i++)
689 defvalues.f_rel[i] = DEFAULT_REL_PREFERENCE;
694 * Shutdown preferences subsystem.
697 GAS_preference_done ()
699 struct PreferenceClient *pc;
700 struct PreferenceClient *next_pc;
702 if (NULL != aging_task)
704 GNUNET_SCHEDULER_cancel (aging_task);
708 while (NULL != (pc = next_pc))
711 GNUNET_CONTAINER_DLL_remove (pc_head,
714 GNUNET_CONTAINER_multipeermap_iterate (pc->peer2pref,
717 GNUNET_CONTAINER_multipeermap_destroy (pc->peer2pref);
720 GNUNET_CONTAINER_multipeermap_iterate (preference_peers,
723 GNUNET_CONTAINER_multipeermap_destroy (preference_peers);
729 * Get the normalized preference values for a specific peer or
730 * the default values if
734 * @return pointer to the values, can be indexed with GNUNET_ATS_PreferenceKind,
735 * default preferences if peer does not exist
738 GAS_preference_get_by_peer (void *cls,
739 const struct GNUNET_PeerIdentity *id)
741 struct PeerRelative *rp;
744 (rp = GNUNET_CONTAINER_multipeermap_get (preference_peers,
747 return defvalues.f_rel;
754 * A performance client disconnected
756 * @param client the client
759 GAS_preference_client_disconnect (struct GNUNET_SERVICE_Client *client)
761 struct PreferenceClient *c_cur;
763 for (c_cur = pc_head; NULL != c_cur; c_cur = c_cur->next)
764 if (client == c_cur->client)
768 GNUNET_CONTAINER_DLL_remove (pc_head,
771 GNUNET_CONTAINER_multipeermap_iterate (c_cur->peer2pref,
774 GNUNET_CONTAINER_multipeermap_destroy (c_cur->peer2pref);
779 /* end of gnunet-service-ats_preferences.c */