Example #1
0
void
te_trigger_stonith_history_sync(void)
{
    /* trigger a sync in 5s to give more nodes the
     * chance to show up so that we don't create
     * unnecessary stonith-history-sync traffic
     */

    /* as we are finally checking the stonith-connection
     * in do_stonith_history_sync we should be fine
     * leaving stonith_history_sync_time & stonith_history_sync_trigger
     * around
     */
    if (stonith_history_sync_trigger == NULL) {
        stonith_history_sync_trigger =
            mainloop_add_trigger(G_PRIORITY_LOW,
                                 do_stonith_history_sync, NULL);
    }

    if(stonith_history_sync_timer == NULL) {
        stonith_history_sync_timer =
            mainloop_timer_add("history_sync", 5000,
                               FALSE, stonith_history_sync_set_trigger,
                               NULL);
    }
    crm_info("Fence history will be synchronized cluster-wide within 5 seconds");
    mainloop_timer_start(stonith_history_sync_timer);
}
static void
election_timeout_start(election_t *e)
{
    if(e) {
        mainloop_timer_start(e->timeout);
    }
}
Example #3
0
void
throttle_init(void)
{
    throttle_records = g_hash_table_new_full(
        crm_str_hash, g_str_equal, NULL, throttle_record_free);
    throttle_timer = mainloop_timer_add("throttle", 30* 1000, TRUE, throttle_timer_cb, NULL);

    throttle_update_job_max(NULL);
    mainloop_timer_start(throttle_timer);
}
Example #4
0
static void
crm_diff_update(const char *event, xmlNode * msg)
{
	int rc = -1;
	const char *op = NULL;
        long now = time(NULL);
        static int updates = 0;
        static mainloop_timer_t *refresh_timer = NULL;

        if(refresh_timer == NULL) {
            refresh_timer = mainloop_timer_add("refresh", 2000, FALSE, mon_trigger_refresh, NULL);
            refresh_trigger = mainloop_add_trigger(G_PRIORITY_LOW, mon_refresh_state, refresh_timer);
        }

        if (current_cib != NULL) {
		xmlNode *cib_last = current_cib;
		current_cib = NULL;

		rc = cib_apply_patch_event(msg, cib_last, &current_cib, LOG_DEBUG);
		free_xml(cib_last);

		switch(rc) {
			case -pcmk_err_diff_resync:
			case -pcmk_err_diff_failed:
                            crm_warn("[%s] %s Patch aborted: %s (%d)", event, op, pcmk_strerror(rc), rc);
                            break;
			case pcmk_ok:
                            updates++;
                            break;
			default:
                            crm_notice("[%s] %s ABORTED: %s (%d)", event, op, pcmk_strerror(rc), rc);
                            break;
		}
	}

	if (current_cib == NULL) {
		current_cib = get_cib_copy(cib);
	}

    /* Refresh
     * - immediately if the last update was more than 5s ago
     * - every 10 updates
     * - at most 2s after the last update
     */
    if (updates > 10 || (now - last_refresh) > (reconnect_msec / 1000)) {
        mon_refresh_state(refresh_timer);
        updates = 0;

    } else {
        mainloop_set_trigger(refresh_trigger);
        mainloop_timer_start(refresh_timer);
    }
}
Example #5
0
guint mainloop_timer_set_period(mainloop_timer_t *t, guint period_ms)
{
    guint last = 0;

    if(t) {
        last = t->period_ms;
        t->period_ms = period_ms;
    }

    if(t && t->id != 0 && last != t->period_ms) {
        mainloop_timer_start(t);
    }
    return last;
}
Example #6
0
void
attrd_peer_update(crm_node_t *peer, xmlNode *xml, bool filter)
{
    bool changed = FALSE;
    attribute_value_t *v = NULL;

    const char *host = crm_element_value(xml, F_ATTRD_HOST);
    const char *attr = crm_element_value(xml, F_ATTRD_ATTRIBUTE);
    const char *value = crm_element_value(xml, F_ATTRD_VALUE);

    attribute_t *a = g_hash_table_lookup(attributes, attr);

    if(a == NULL) {
        a = create_attribute(xml);
    }

    v = g_hash_table_lookup(a->values, host);

    if(v == NULL) {
        crm_trace("Setting %s[%s] to %s from %s", attr, host, value, peer->uname);
        v = calloc(1, sizeof(attribute_value_t));
        if(value) {
            v->current = strdup(value);
        }
        v->nodename = strdup(host);
        crm_element_value_int(xml, F_ATTRD_IS_REMOTE, &v->is_remote);
        g_hash_table_replace(a->values, v->nodename, v);

        if (v->is_remote == TRUE) {
            crm_remote_peer_cache_add(host);
        }

        changed = TRUE;

    } else if(filter
              && safe_str_neq(v->current, value)
              && safe_str_eq(host, attrd_cluster->uname)) {
        xmlNode *sync = create_xml_node(NULL, __FUNCTION__);
        crm_notice("%s[%s]: local value '%s' takes priority over '%s' from %s",
                   a->id, host, v->current, value, peer->uname);

        crm_xml_add(sync, F_ATTRD_TASK, "sync-response");
        v = g_hash_table_lookup(a->values, host);
        build_attribute_xml(sync, a->id, a->set, a->uuid, a->timeout_ms, a->user, v->nodename, v->nodeid, v->current);

        crm_xml_add_int(sync, F_ATTRD_WRITER, election_state(writer));
        send_cluster_message(peer, crm_msg_attrd, sync, TRUE);
        free_xml(sync);

    } else if(safe_str_neq(v->current, value)) {
        crm_info("Setting %s[%s]: %s -> %s from %s", attr, host, v->current, value, peer->uname);
        free(v->current);
        if(value) {
            v->current = strdup(value);
        } else {
            v->current = NULL;
        }
        changed = TRUE;

    } else {
        crm_trace("Unchanged %s[%s] from %s is %s", attr, host, peer->uname, value);
    }

    a->changed |= changed;

    /* this only involves cluster nodes. */
    if(v->nodeid == 0 && (v->is_remote == FALSE)) {
        if(crm_element_value_int(xml, F_ATTRD_HOST_ID, (int*)&v->nodeid) == 0) {
            /* Create the name/id association */
            crm_node_t *peer = crm_get_peer(v->nodeid, host);
            crm_trace("We know %s's node id now: %s", peer->uname, peer->uuid);
            if(election_state(writer) == election_won) {
                write_attributes(FALSE, TRUE);
                return;
            }
        }
    }

    if(changed) {
        if(a->timer) {
            crm_trace("Delayed write out (%dms) for %s", a->timeout_ms, a->id);
            mainloop_timer_start(a->timer);
        } else {
            write_or_elect_attribute(a);
        }
    }
}
Example #7
0
void
attrd_peer_update(crm_node_t *peer, xmlNode *xml, const char *host, bool filter)
{
    bool changed = FALSE;
    attribute_t *a;
    attribute_value_t *v = NULL;
    int dampen = 0;

    const char *op = crm_element_value(xml, F_ATTRD_TASK);
    const char *attr = crm_element_value(xml, F_ATTRD_ATTRIBUTE);
    const char *value = crm_element_value(xml, F_ATTRD_VALUE);
    const char *dvalue = crm_element_value(xml, F_ATTRD_DAMPEN);

    if (attr == NULL) {
        crm_warn("Peer update did not specify attribute");
        return;
    }

    a = g_hash_table_lookup(attributes, attr);
    if(a == NULL) {
        if (op == NULL /* The xml children from an ATTRD_OP_SYNC_RESPONSE have no F_ATTRD_TASK */
            || safe_str_eq(op, ATTRD_OP_UPDATE)
            || safe_str_eq(op, ATTRD_OP_UPDATE_BOTH)) {
            a = create_attribute(xml);
        } else {
            crm_warn("Update error (attribute %s not found)", attr);
            return;
        }
    }
    
    if (op == NULL /* The xml children from an ATTRD_OP_SYNC_RESPONSE have no F_ATTRD_TASK */
        || safe_str_eq(op, ATTRD_OP_UPDATE_BOTH)
        || safe_str_eq(op, ATTRD_OP_UPDATE_DELAY)) {
        if (dvalue) {
            dampen = crm_get_msec(dvalue); 
            if (dampen >= 0) {
                if (a->timeout_ms != dampen) {
                    mainloop_timer_stop(a->timer);
                    mainloop_timer_del(a->timer);
                    a->timeout_ms = dampen;
                    if (dampen > 0) {
                        a->timer = mainloop_timer_add(a->id, a->timeout_ms, FALSE, attribute_timer_cb, a);
                        crm_info("Update attribute %s with delay %dms (%s)", a->id, dampen, dvalue);
                    } else {
                        a->timer = NULL;
                        crm_info("Update attribute %s with not delay", a->id);
                    }
                    //if dampen is changed, attrd writes in a current value immediately.
                    write_or_elect_attribute(a);
                    if (safe_str_eq(op, ATTRD_OP_UPDATE_DELAY)) {
                        return;
                    }
                } else {
                    if (safe_str_eq(op, ATTRD_OP_UPDATE_DELAY)) {
                        crm_trace("Unchanged attribute %s with delay %dms (%s).(ATTRD_OP_UPDATE_DELAY)", a->id, dampen, dvalue);
                        return;
                    }
                }
            } else {
                crm_warn("Update error (A positive number is necessary for delay parameter. attribute %s : %dms (%s))", a->id, dampen, dvalue);
                return;
            }
        } else {
            crm_warn("Update error (delay parameter is necessary for the update of the attribute %s)", a->id);
            return;
        }
    }

    if(host == NULL) {
        GHashTableIter vIter;
        g_hash_table_iter_init(&vIter, a->values);

        crm_debug("Setting %s for all hosts to %s", attr, value);

        xml_remove_prop(xml, F_ATTRD_HOST_ID);
        while (g_hash_table_iter_next(&vIter, (gpointer *) & host, NULL)) {
            attrd_peer_update(peer, xml, host, filter);
        }
        return;
    }

    v = attrd_lookup_or_create_value(a->values, host, xml);

    if(filter
              && safe_str_neq(v->current, value)
              && safe_str_eq(host, attrd_cluster->uname)) {
        xmlNode *sync = create_xml_node(NULL, __FUNCTION__);
        crm_notice("%s[%s]: local value '%s' takes priority over '%s' from %s",
                   a->id, host, v->current, value, peer->uname);

        crm_xml_add(sync, F_ATTRD_TASK, ATTRD_OP_SYNC_RESPONSE);
        v = g_hash_table_lookup(a->values, host);
        build_attribute_xml(sync, a->id, a->set, a->uuid, a->timeout_ms, a->user, a->is_private,
                            v->nodename, v->nodeid, v->current);

        crm_xml_add_int(sync, F_ATTRD_WRITER, election_state(writer));
        send_attrd_message(peer, sync);
        free_xml(sync);

    } else if(safe_str_neq(v->current, value)) {
        crm_info("Setting %s[%s]: %s -> %s from %s", attr, host, v->current, value, peer->uname);
        free(v->current);
        if(value) {
            v->current = strdup(value);
        } else {
            v->current = NULL;
        }
        changed = TRUE;
    } else {
        crm_trace("Unchanged %s[%s] from %s is %s", attr, host, peer->uname, value);
    }

    a->changed |= changed;

    if(changed) {
        if(a->timer) {
            crm_trace("Delayed write out (%dms) for %s", a->timeout_ms, a->id);
            mainloop_timer_start(a->timer);
        } else {
            write_or_elect_attribute(a);
        }
    }

    /* this only involves cluster nodes. */
    if(v->nodeid == 0 && (v->is_remote == FALSE)) {
        if(crm_element_value_int(xml, F_ATTRD_HOST_ID, (int*)&v->nodeid) == 0) {
            /* Create the name/id association */
            crm_node_t *peer = crm_get_peer(v->nodeid, host);
            crm_trace("We know %s's node id now: %s", peer->uname, peer->uuid);
            if(election_state(writer) == election_won) {
                write_attributes(FALSE, TRUE);
                return;
            }
        }
    }
}
Example #8
0
void
attrd_peer_update(crm_node_t *peer, xmlNode *xml, const char *host, bool filter)
{
    bool changed = FALSE;
    attribute_value_t *v = NULL;

    const char *attr = crm_element_value(xml, F_ATTRD_ATTRIBUTE);
    const char *value = crm_element_value(xml, F_ATTRD_VALUE);

    attribute_t *a = g_hash_table_lookup(attributes, attr);

    if(a == NULL) {
        a = create_attribute(xml);
    }

    if(host == NULL) {
        GHashTableIter vIter;
        g_hash_table_iter_init(&vIter, a->values);

        crm_debug("Setting %s for all hosts to %s", attr, value);

        xml_remove_prop(xml, F_ATTRD_HOST_ID);
        while (g_hash_table_iter_next(&vIter, (gpointer *) & host, NULL)) {
            attrd_peer_update(peer, xml, host, filter);
        }
        return;
    }

    v = attrd_lookup_or_create_value(a->values, host, xml);

    if(filter
              && safe_str_neq(v->current, value)
              && safe_str_eq(host, attrd_cluster->uname)) {
        xmlNode *sync = create_xml_node(NULL, __FUNCTION__);
        crm_notice("%s[%s]: local value '%s' takes priority over '%s' from %s",
                   a->id, host, v->current, value, peer->uname);

        crm_xml_add(sync, F_ATTRD_TASK, ATTRD_OP_SYNC_RESPONSE);
        v = g_hash_table_lookup(a->values, host);
        build_attribute_xml(sync, a->id, a->set, a->uuid, a->timeout_ms, a->user, a->is_private,
                            v->nodename, v->nodeid, v->current);

        crm_xml_add_int(sync, F_ATTRD_WRITER, election_state(writer));
        send_attrd_message(peer, sync);
        free_xml(sync);

    } else if(safe_str_neq(v->current, value)) {
        crm_info("Setting %s[%s]: %s -> %s from %s", attr, host, v->current, value, peer->uname);
        free(v->current);
        if(value) {
            v->current = strdup(value);
        } else {
            v->current = NULL;
        }
        changed = TRUE;

    } else {
        crm_trace("Unchanged %s[%s] from %s is %s", attr, host, peer->uname, value);
    }

    a->changed |= changed;

    if(changed) {
        if(a->timer) {
            crm_trace("Delayed write out (%dms) for %s", a->timeout_ms, a->id);
            mainloop_timer_start(a->timer);
        } else {
            write_or_elect_attribute(a);
        }
    }

    /* this only involves cluster nodes. */
    if(v->nodeid == 0 && (v->is_remote == FALSE)) {
        if(crm_element_value_int(xml, F_ATTRD_HOST_ID, (int*)&v->nodeid) == 0) {
            /* Create the name/id association */
            crm_node_t *peer = crm_get_peer(v->nodeid, host);
            crm_trace("We know %s's node id now: %s", peer->uname, peer->uuid);
            if(election_state(writer) == election_won) {
                write_attributes(FALSE, TRUE);
                return;
            }
        }
    }
}
Example #9
0
int
cib_process_command(xmlNode * request, xmlNode ** reply, xmlNode ** cib_diff, gboolean privileged)
{
    xmlNode *input = NULL;
    xmlNode *output = NULL;
    xmlNode *result_cib = NULL;
    xmlNode *current_cib = NULL;

    int call_type = 0;
    int call_options = 0;

    const char *op = NULL;
    const char *section = NULL;
    const char *call_id = crm_element_value(request, F_CIB_CALLID);

    int rc = pcmk_ok;
    int rc2 = pcmk_ok;

    gboolean send_r_notify = FALSE;
    gboolean global_update = FALSE;
    gboolean config_changed = FALSE;
    gboolean manage_counters = TRUE;

    static mainloop_timer_t *digest_timer = NULL;

    CRM_ASSERT(cib_status == pcmk_ok);

    if(digest_timer == NULL) {
        digest_timer = mainloop_timer_add("digester", 5000, FALSE, cib_digester_cb, NULL);
    }

    *reply = NULL;
    *cib_diff = NULL;
    current_cib = the_cib;

    /* Start processing the request... */
    op = crm_element_value(request, F_CIB_OPERATION);
    crm_element_value_int(request, F_CIB_CALLOPTS, &call_options);
    rc = cib_get_operation_id(op, &call_type);

    if (rc == pcmk_ok && privileged == FALSE) {
        rc = cib_op_can_run(call_type, call_options, privileged, global_update);
    }

    rc2 = cib_op_prepare(call_type, request, &input, &section);
    if (rc == pcmk_ok) {
        rc = rc2;
    }

    if (rc != pcmk_ok) {
        crm_trace("Call setup failed: %s", pcmk_strerror(rc));
        goto done;

    } else if (cib_op_modifies(call_type) == FALSE) {
        rc = cib_perform_op(op, call_options, cib_op_func(call_type), TRUE,
                            section, request, input, FALSE, &config_changed,
                            current_cib, &result_cib, NULL, &output);

        CRM_CHECK(result_cib == NULL, free_xml(result_cib));
        goto done;
    }

    /* Handle a valid write action */
    global_update = crm_is_true(crm_element_value(request, F_CIB_GLOBAL_UPDATE));
    if (global_update) {
        /* legacy code */
        manage_counters = FALSE;
        call_options |= cib_force_diff;
        crm_trace("Global update detected");

        CRM_CHECK(call_type == 3 || call_type == 4, crm_err("Call type: %d", call_type);
                  crm_log_xml_err(request, "bad op"));
    }

    if (rc == pcmk_ok) {
        ping_modified_since = TRUE;
        if (call_options & cib_inhibit_bcast) {
            /* skip */
            crm_trace("Skipping update: inhibit broadcast");
            manage_counters = FALSE;
        }

        if (is_not_set(call_options, cib_dryrun) && safe_str_eq(section, XML_CIB_TAG_STATUS)) {
            /* Copying large CIBs accounts for a huge percentage of our CIB usage */
            call_options |= cib_zero_copy;
        } else {
            clear_bit(call_options, cib_zero_copy);
        }

        /* result_cib must not be modified after cib_perform_op() returns */
        rc = cib_perform_op(op, call_options, cib_op_func(call_type), FALSE,
                            section, request, input, manage_counters, &config_changed,
                            current_cib, &result_cib, cib_diff, &output);

        if (manage_counters == FALSE) {
            /* Legacy code
             * If the diff is NULL at this point, its because nothing changed
             */
            config_changed = cib_config_changed(NULL, NULL, cib_diff);
        }

        /* Always write to disk for replace ops,
         * this also negates the need to detect ordering changes
         */
        if (crm_str_eq(CIB_OP_REPLACE, op, TRUE)) {
            config_changed = TRUE;
        }
    }

    if (rc == pcmk_ok && is_not_set(call_options, cib_dryrun)) {
        if(is_not_set(call_options, cib_zero_copy)) {
            rc = activateCibXml(result_cib, config_changed, op);
        }

        if (rc == pcmk_ok && cib_internal_config_changed(*cib_diff)) {
            cib_read_config(config_hash, result_cib);
        }

        if (crm_str_eq(CIB_OP_REPLACE, op, TRUE)) {
            if (section == NULL) {
                send_r_notify = TRUE;

            } else if (safe_str_eq(section, XML_TAG_CIB)) {
                send_r_notify = TRUE;

            } else if (safe_str_eq(section, XML_CIB_TAG_NODES)) {
                send_r_notify = TRUE;

            } else if (safe_str_eq(section, XML_CIB_TAG_STATUS)) {
                send_r_notify = TRUE;
            }

        } else if (crm_str_eq(CIB_OP_ERASE, op, TRUE)) {
            send_r_notify = TRUE;
        }

        mainloop_timer_stop(digest_timer);
        mainloop_timer_start(digest_timer);

    } else if (rc == -pcmk_err_schema_validation) {
        CRM_ASSERT(is_not_set(call_options, cib_zero_copy));

        if (output != NULL) {
            crm_log_xml_info(output, "cib:output");
            free_xml(output);
        }

        output = result_cib;

    } else {
        if(is_not_set(call_options, cib_zero_copy)) {
            free_xml(result_cib);
        }
    }

    if ((call_options & cib_inhibit_notify) == 0) {
        const char *client = crm_element_value(request, F_CIB_CLIENTNAME);

        crm_trace("Sending notifications");
        cib_diff_notify(call_options, client, call_id, op, input, rc, *cib_diff);
    }

    if (send_r_notify) {
        const char *origin = crm_element_value(request, F_ORIG);

        cib_replace_notify(origin, the_cib, rc, *cib_diff);
    }

    xml_log_patchset(LOG_TRACE, "cib:diff", *cib_diff);
  done:
    if ((call_options & cib_discard_reply) == 0) {
        const char *caller = crm_element_value(request, F_CIB_CLIENTID);

        *reply = create_xml_node(NULL, "cib-reply");
        crm_xml_add(*reply, F_TYPE, T_CIB);
        crm_xml_add(*reply, F_CIB_OPERATION, op);
        crm_xml_add(*reply, F_CIB_CALLID, call_id);
        crm_xml_add(*reply, F_CIB_CLIENTID, caller);
        crm_xml_add_int(*reply, F_CIB_CALLOPTS, call_options);
        crm_xml_add_int(*reply, F_CIB_RC, rc);

        if (output != NULL) {
            crm_trace("Attaching reply output");
            add_message_xml(*reply, F_CIB_CALLDATA, output);
        }

        crm_log_xml_explicit(*reply, "cib:reply");
    }

    crm_trace("cleanup");

    if (cib_op_modifies(call_type) == FALSE && output != current_cib) {
        free_xml(output);
        output = NULL;
    }

    if (call_type >= 0) {
        cib_op_cleanup(call_type, call_options, &input, &output);
    }

    crm_trace("done");
    return rc;
}
Example #10
0
static void
attrd_cib_callback(xmlNode * msg, int call_id, int rc, xmlNode * output, void *user_data)
{
    int level = LOG_ERR;
    GHashTableIter iter;
    const char *peer = NULL;
    attribute_value_t *v = NULL;

    char *name = user_data;
    attribute_t *a = g_hash_table_lookup(attributes, name);

    if(a == NULL) {
        crm_info("Attribute %s no longer exists", name);
        return;
    }

    a->update = 0;
    if (rc == pcmk_ok && call_id < 0) {
        rc = call_id;
    }

    switch (rc) {
        case pcmk_ok:
            level = LOG_INFO;
            last_cib_op_done = call_id;
            if (a->timer && !a->timeout_ms) {
                // Remove temporary dampening for failed writes
                mainloop_timer_del(a->timer);
                a->timer = NULL;
            }
            break;

        case -pcmk_err_diff_failed:    /* When an attr changes while the CIB is syncing */
        case -ETIME:           /* When an attr changes while there is a DC election */
        case -ENXIO:           /* When an attr changes while the CIB is syncing a
                                *   newer config from a node that just came up
                                */
            level = LOG_WARNING;
            break;
    }

    do_crm_log(level, "CIB update %d result for %s: %s " CRM_XS " rc=%d",
               call_id, a->id, pcmk_strerror(rc), rc);

    g_hash_table_iter_init(&iter, a->values);
    while (g_hash_table_iter_next(&iter, (gpointer *) & peer, (gpointer *) & v)) {
        do_crm_log(level, "* %s[%s]=%s", a->id, peer, v->requested);
        free(v->requested);
        v->requested = NULL;
        if (rc != pcmk_ok) {
            a->changed = TRUE; /* Attempt write out again */
        }
    }

    if (a->changed && attrd_election_won()) {
        if (rc == pcmk_ok) {
            /* We deferred a write of a new update because this update was in
             * progress. Write out the new value without additional delay.
             */
            write_attribute(a, FALSE);

        /* We're re-attempting a write because the original failed; delay
         * the next attempt so we don't potentially flood the CIB manager
         * and logs with a zillion attempts per second.
         *
         * @TODO We could elect a new writer instead. However, we'd have to
         * somehow downgrade our vote, and we'd still need something like this
         * if all peers similarly fail to write this attribute (which may
         * indicate a corrupted attribute entry rather than a CIB issue).
         */
        } else if (a->timer) {
            // Attribute has a dampening value, so use that as delay
            if (!mainloop_timer_running(a->timer)) {
                crm_trace("Delayed re-attempted write (%dms) for %s",
                          a->timeout_ms, name);
                mainloop_timer_start(a->timer);
            }
        } else {
            /* Set a temporary dampening of 2 seconds (timer will continue
             * to exist until the attribute's dampening gets set or the
             * write succeeds).
             */
            a->timer = mainloop_timer_add(a->id, 2000, FALSE,
                                          attribute_timer_cb, a);
            mainloop_timer_start(a->timer);
        }
    }
}
Example #11
0
void
attrd_peer_update(crm_node_t *peer, xmlNode *xml, const char *host, bool filter)
{
    bool update_both = FALSE;
    attribute_t *a;
    attribute_value_t *v = NULL;
    gboolean is_force_write = FALSE;

    const char *op = crm_element_value(xml, F_ATTRD_TASK);
    const char *attr = crm_element_value(xml, F_ATTRD_ATTRIBUTE);
    const char *value = crm_element_value(xml, F_ATTRD_VALUE);
    crm_element_value_int(xml, F_ATTRD_IS_FORCE_WRITE, &is_force_write);

    if (attr == NULL) {
        crm_warn("Could not update attribute: peer did not specify name");
        return;
    }

    update_both = ((op == NULL) // ATTRD_OP_SYNC_RESPONSE has no F_ATTRD_TASK
                   || safe_str_eq(op, ATTRD_OP_UPDATE_BOTH));

    // Look up or create attribute entry
    a = g_hash_table_lookup(attributes, attr);
    if (a == NULL) {
        if (update_both || safe_str_eq(op, ATTRD_OP_UPDATE)) {
            a = create_attribute(xml);
        } else {
            crm_warn("Could not update %s: attribute not found", attr);
            return;
        }
    }

    // Update attribute dampening
    if (update_both || safe_str_eq(op, ATTRD_OP_UPDATE_DELAY)) {
        const char *dvalue = crm_element_value(xml, F_ATTRD_DAMPEN);
        int dampen = 0;

        if (dvalue == NULL) {
            crm_warn("Could not update %s: peer did not specify value for delay",
                     attr);
            return;
        }

        dampen = crm_get_msec(dvalue);
        if (dampen < 0) {
            crm_warn("Could not update %s: invalid delay value %dms (%s)",
                     attr, dampen, dvalue);
            return;
        }

        if (a->timeout_ms != dampen) {
            mainloop_timer_del(a->timer);
            a->timeout_ms = dampen;
            if (dampen > 0) {
                a->timer = mainloop_timer_add(attr, a->timeout_ms, FALSE,
                                              attribute_timer_cb, a);
                crm_info("Update attribute %s delay to %dms (%s)",
                         attr, dampen, dvalue);
            } else {
                a->timer = NULL;
                crm_info("Update attribute %s to remove delay", attr);
            }

            /* If dampening changed, do an immediate write-out,
             * otherwise repeated dampening changes would prevent write-outs
             */
            write_or_elect_attribute(a);
        }

        if (!update_both) {
            return;
        }
    }

    // If no host was specified, update all hosts recursively
    if (host == NULL) {
        GHashTableIter vIter;

        crm_debug("Setting %s for all hosts to %s", attr, value);
        xml_remove_prop(xml, F_ATTRD_HOST_ID);
        g_hash_table_iter_init(&vIter, a->values);
        while (g_hash_table_iter_next(&vIter, (gpointer *) & host, NULL)) {
            attrd_peer_update(peer, xml, host, filter);
        }
        return;
    }

    // Update attribute value for one host

    v = attrd_lookup_or_create_value(a->values, host, xml);

    if (filter && safe_str_neq(v->current, value)
        && safe_str_eq(host, attrd_cluster->uname)) {

        xmlNode *sync = create_xml_node(NULL, __FUNCTION__);

        crm_notice("%s[%s]: local value '%s' takes priority over '%s' from %s",
                   attr, host, v->current, value, peer->uname);

        crm_xml_add(sync, F_ATTRD_TASK, ATTRD_OP_SYNC_RESPONSE);
        v = g_hash_table_lookup(a->values, host);
        build_attribute_xml(sync, attr, a->set, a->uuid, a->timeout_ms, a->user,
                            a->is_private, v->nodename, v->nodeid, v->current, FALSE);

        attrd_xml_add_writer(sync);

        /* Broadcast in case any other nodes had the inconsistent value */
        send_attrd_message(NULL, sync);
        free_xml(sync);

    } else if (safe_str_neq(v->current, value)) {
        crm_info("Setting %s[%s]: %s -> %s from %s",
                 attr, host, v->current, value, peer->uname);
        free(v->current);
        v->current = (value? strdup(value) : NULL);
        a->changed = TRUE;

        // Write out new value or start dampening timer
        if (a->timeout_ms && a->timer) {
            crm_trace("Delayed write out (%dms) for %s", a->timeout_ms, attr);
            mainloop_timer_start(a->timer);
        } else {
            write_or_elect_attribute(a);
        }

    } else {
        if (is_force_write && a->timeout_ms && a->timer) {
            /* Save forced writing and set change flag. */
            /* The actual attribute is written by Writer after election. */
            crm_trace("Unchanged %s[%s] from %s is %s(Set the forced write flag)", attr, host, peer->uname, value);
            a->force_write = TRUE;
        } else {
            crm_trace("Unchanged %s[%s] from %s is %s", attr, host, peer->uname, value);
        }
    }

    /* Set the seen flag for attribute processing held only in the own node. */
    v->seen = TRUE;

    /* If this is a cluster node whose node ID we are learning, remember it */
    if ((v->nodeid == 0) && (v->is_remote == FALSE)
        && (crm_element_value_int(xml, F_ATTRD_HOST_ID, (int*)&v->nodeid) == 0)) {

        crm_node_t *known_peer = crm_get_peer(v->nodeid, host);

        crm_trace("Learned %s has node id %s",
                  known_peer->uname, known_peer->uuid);
        if (attrd_election_won()) {
            write_attributes(FALSE, FALSE);
        }
    }
}