Merge remote branch 'origin/master' into topic/bernhard/sqlite

This commit is contained in:
Bernhard Amann 2013-05-12 20:47:55 -07:00
commit 747ba68030
78 changed files with 2650 additions and 1387 deletions

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##! This implements transparent cluster support for the metrics framework.
##! Do not load this file directly. It's only meant to be loaded automatically
##! and will be depending on if the cluster framework has been enabled.
##! The goal of this script is to make metric calculation completely and
##! transparently automated when running on a cluster.
##!
##! Events defined here are not exported deliberately because they are meant
##! to be an internal implementation detail.
@load base/frameworks/cluster
@load ./main
module Metrics;
export {
## Allows a user to decide how large of result groups the
## workers should transmit values for cluster metric aggregation.
const cluster_send_in_groups_of = 50 &redef;
## The percent of the full threshold value that needs to be met
## on a single worker for that worker to send the value to its manager in
## order for it to request a global view for that value. There is no
## requirement that the manager requests a global view for the index
## since it may opt not to if it requested a global view for the index
## recently.
const cluster_request_global_view_percent = 0.1 &redef;
## Event sent by the manager in a cluster to initiate the
## collection of metrics values for a filter.
global cluster_filter_request: event(uid: string, id: ID, filter_name: string);
## Event sent by nodes that are collecting metrics after receiving
## a request for the metric filter from the manager.
global cluster_filter_response: event(uid: string, id: ID, filter_name: string, data: MetricTable, done: bool);
## This event is sent by the manager in a cluster to initiate the
## collection of a single index value from a filter. It's typically
## used to get intermediate updates before the break interval triggers
## to speed detection of a value crossing a threshold.
global cluster_index_request: event(uid: string, id: ID, filter_name: string, index: Index);
## This event is sent by nodes in response to a
## :bro:id:`Metrics::cluster_index_request` event.
global cluster_index_response: event(uid: string, id: ID, filter_name: string, index: Index, val: count);
## This is sent by workers to indicate that they crossed the percent of the
## current threshold by the percentage defined globally in
## :bro:id:`Metrics::cluster_request_global_view_percent`
global cluster_index_intermediate_response: event(id: Metrics::ID, filter_name: string, index: Metrics::Index, val: count);
## This event is scheduled internally on workers to send result chunks.
global send_data: event(uid: string, id: ID, filter_name: string, data: MetricTable);
}
# This is maintained by managers so they can know what data they requested and
# when they requested it.
global requested_results: table[string] of time = table() &create_expire=5mins;
# TODO: The next 4 variables make the assumption that a value never
# takes longer than 5 minutes to transmit from workers to manager. This needs to
# be tunable or self-tuning. These should also be restructured to be
# maintained within a single variable.
# This variable is maintained by manager nodes as they collect and aggregate
# results.
global filter_results: table[string, ID, string] of MetricTable &create_expire=5mins;
# This variable is maintained by manager nodes to track how many "dones" they
# collected per collection unique id. Once the number of results for a uid
# matches the number of peer nodes that results should be coming from, the
# result is written out and deleted from here.
# TODO: add an &expire_func in case not all results are received.
global done_with: table[string] of count &create_expire=5mins &default=0;
# This variable is maintained by managers to track intermediate responses as
# they are getting a global view for a certain index.
global index_requests: table[string, ID, string, Index] of count &create_expire=5mins &default=0;
# This variable is maintained by all hosts for different purposes. Non-managers
# maintain it to know what indexes they have recently sent as intermediate
# updates so they don't overwhelm their manager. Managers maintain it so they
# don't overwhelm workers with intermediate index requests. The count that is
# yielded is the number of times the percentage threshold has been crossed and
# an intermediate result has been received. The manager may optionally request
# the index again before data expires from here if too many workers are crossing
# the percentage threshold (not implemented yet!).
global recent_global_view_indexes: table[ID, string, Index] of count &create_expire=5mins &default=0;
# Add events to the cluster framework to make this work.
redef Cluster::manager2worker_events += /Metrics::cluster_(filter_request|index_request)/;
redef Cluster::worker2manager_events += /Metrics::cluster_(filter_response|index_response|index_intermediate_response)/;
@if ( Cluster::local_node_type() != Cluster::MANAGER )
# This is done on all non-manager node types in the event that a metric is
# being collected somewhere other than a worker.
function data_added(filter: Filter, index: Index, val: count)
{
# If an intermediate update for this value was sent recently, don't send
# it again.
if ( [filter$id, filter$name, index] in recent_global_view_indexes )
return;
# If val is 5 and global view % is 0.1 (10%), pct_val will be 50. If that
# crosses the full threshold then it's a candidate to send as an
# intermediate update.
local pct_val = double_to_count(val / cluster_request_global_view_percent);
if ( check_notice(filter, index, pct_val) )
{
# kick off intermediate update
event Metrics::cluster_index_intermediate_response(filter$id, filter$name, index, val);
++recent_global_view_indexes[filter$id, filter$name, index];
}
}
event Metrics::send_data(uid: string, id: ID, filter_name: string, data: MetricTable)
{
#print fmt("WORKER %s: sending data for uid %s...", Cluster::node, uid);
local local_data: MetricTable;
local num_added = 0;
for ( index in data )
{
local_data[index] = data[index];
delete data[index];
# Only send cluster_send_in_groups_of at a time. Queue another
# event to send the next group.
if ( cluster_send_in_groups_of == ++num_added )
break;
}
local done = F;
# If data is empty, this metric is done.
if ( |data| == 0 )
done = T;
event Metrics::cluster_filter_response(uid, id, filter_name, local_data, done);
if ( ! done )
event Metrics::send_data(uid, id, filter_name, data);
}
event Metrics::cluster_filter_request(uid: string, id: ID, filter_name: string)
{
#print fmt("WORKER %s: received the cluster_filter_request event.", Cluster::node);
# Initiate sending all of the data for the requested filter.
event Metrics::send_data(uid, id, filter_name, store[id, filter_name]);
# Lookup the actual filter and reset it, the reference to the data
# currently stored will be maintained interally by the send_data event.
reset(filter_store[id, filter_name]);
}
event Metrics::cluster_index_request(uid: string, id: ID, filter_name: string, index: Index)
{
local val=0;
if ( index in store[id, filter_name] )
val = store[id, filter_name][index];
# fmt("WORKER %s: received the cluster_index_request event for %s=%d.", Cluster::node, index2str(index), val);
event Metrics::cluster_index_response(uid, id, filter_name, index, val);
}
@endif
@if ( Cluster::local_node_type() == Cluster::MANAGER )
# Manager's handle logging.
event Metrics::log_it(filter: Filter)
{
#print fmt("%.6f MANAGER: breaking %s filter for %s metric", network_time(), filter$name, filter$id);
local uid = unique_id("");
# Set some tracking variables.
requested_results[uid] = network_time();
filter_results[uid, filter$id, filter$name] = table();
# Request data from peers.
event Metrics::cluster_filter_request(uid, filter$id, filter$name);
# Schedule the log_it event for the next break period.
schedule filter$break_interval { Metrics::log_it(filter) };
}
# This is unlikely to be called often, but it's here in case there are metrics
# being collected by managers.
function data_added(filter: Filter, index: Index, val: count)
{
if ( check_notice(filter, index, val) )
do_notice(filter, index, val);
}
event Metrics::cluster_index_response(uid: string, id: ID, filter_name: string, index: Index, val: count)
{
#print fmt("%0.6f MANAGER: receiving index data from %s", network_time(), get_event_peer()$descr);
if ( [uid, id, filter_name, index] !in index_requests )
index_requests[uid, id, filter_name, index] = 0;
index_requests[uid, id, filter_name, index] += val;
local ir = index_requests[uid, id, filter_name, index];
++done_with[uid];
if ( Cluster::worker_count == done_with[uid] )
{
if ( check_notice(filter_store[id, filter_name], index, ir) )
do_notice(filter_store[id, filter_name], index, ir);
delete done_with[uid];
delete index_requests[uid, id, filter_name, index];
}
}
# Managers handle intermediate updates here.
event Metrics::cluster_index_intermediate_response(id: ID, filter_name: string, index: Index, val: count)
{
#print fmt("MANAGER: receiving intermediate index data from %s", get_event_peer()$descr);
#print fmt("MANAGER: requesting index data for %s", index2str(index));
local uid = unique_id("");
event Metrics::cluster_index_request(uid, id, filter_name, index);
++recent_global_view_indexes[id, filter_name, index];
}
event Metrics::cluster_filter_response(uid: string, id: ID, filter_name: string, data: MetricTable, done: bool)
{
#print fmt("MANAGER: receiving results from %s", get_event_peer()$descr);
local local_data = filter_results[uid, id, filter_name];
for ( index in data )
{
if ( index !in local_data )
local_data[index] = 0;
local_data[index] += data[index];
}
# Mark another worker as being "done" for this uid.
if ( done )
++done_with[uid];
# If the data has been collected from all peers, we are done and ready to log.
if ( Cluster::worker_count == done_with[uid] )
{
local ts = network_time();
# Log the time this was initially requested if it's available.
if ( uid in requested_results )
{
ts = requested_results[uid];
delete requested_results[uid];
}
write_log(ts, filter_store[id, filter_name], local_data);
# Clean up
delete filter_results[uid, id, filter_name];
delete done_with[uid];
}
}
@endif

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##! The metrics framework provides a way to count and measure data.
@load base/frameworks/notice
module Metrics;
export {
## The metrics logging stream identifier.
redef enum Log::ID += { LOG };
## Identifiers for metrics to collect.
type ID: enum {
## Blank placeholder value.
NOTHING,
};
## The default interval used for "breaking" metrics and writing the
## current value to the logging stream.
const default_break_interval = 15mins &redef;
## This is the interval for how often threshold based notices will happen
## after they have already fired.
const renotice_interval = 1hr &redef;
## Represents a thing which is having metrics collected for it. An instance
## of this record type and a :bro:type:`Metrics::ID` together represent a
## single measurement.
type Index: record {
## Host is the value to which this metric applies.
host: addr &optional;
## A non-address related metric or a sub-key for an address based metric.
## An example might be successful SSH connections by client IP address
## where the client string would be the index value.
## Another example might be number of HTTP requests to a particular
## value in a Host header. This is an example of a non-host based
## metric since multiple IP addresses could respond for the same Host
## header value.
str: string &optional;
## The CIDR block that this metric applies to. This is typically
## only used internally for host based aggregation.
network: subnet &optional;
} &log;
## The record type that is used for logging metrics.
type Info: record {
## Timestamp at which the metric was "broken".
ts: time &log;
## What measurement the metric represents.
metric_id: ID &log;
## The name of the filter being logged. :bro:type:`Metrics::ID` values
## can have multiple filters which represent different perspectives on
## the data so this is necessary to understand the value.
filter_name: string &log;
## What the metric value applies to.
index: Index &log;
## The simple numeric value of the metric.
value: count &log;
};
# TODO: configure a metrics filter logging stream to log the current
# metrics configuration in case someone is looking through
# old logs and the configuration has changed since then.
## Filters define how the data from a metric is aggregated and handled.
## Filters can be used to set how often the measurements are cut or "broken"
## and logged or how the data within them is aggregated. It's also
## possible to disable logging and use filters for thresholding.
type Filter: record {
## The :bro:type:`Metrics::ID` that this filter applies to.
id: ID &optional;
## The name for this filter so that multiple filters can be
## applied to a single metrics to get a different view of the same
## metric data being collected (different aggregation, break, etc).
name: string &default="default";
## A predicate so that you can decide per index if you would like
## to accept the data being inserted.
pred: function(index: Index): bool &optional;
## Global mask by which you'd like to aggregate traffic.
aggregation_mask: count &optional;
## This is essentially a mapping table between addresses and subnets.
aggregation_table: table[subnet] of subnet &optional;
## The interval at which this filter should be "broken" and written
## to the logging stream. The counters are also reset to zero at
## this time so any threshold based detection needs to be set to a
## number that should be expected to happen within this period.
break_interval: interval &default=default_break_interval;
## This determines if the result of this filter is sent to the metrics
## logging stream. One use for the logging framework is as an internal
## thresholding and statistics gathering utility that is meant to
## never log but rather to generate notices and derive data.
log: bool &default=T;
## If this and a $notice_threshold value are set, this notice type
## will be generated by the metrics framework.
note: Notice::Type &optional;
## A straight threshold for generating a notice.
notice_threshold: count &optional;
## A series of thresholds at which to generate notices.
notice_thresholds: vector of count &optional;
## How often this notice should be raised for this filter. It
## will be generated everytime it crosses a threshold, but if the
## $break_interval is set to 5mins and this is set to 1hr the notice
## only be generated once per hour even if something crosses the
## threshold in every break interval.
notice_freq: interval &optional;
};
## Function to associate a metric filter with a metric ID.
##
## id: The metric ID that the filter should be associated with.
##
## filter: The record representing the filter configuration.
global add_filter: function(id: ID, filter: Filter);
## Add data into a :bro:type:`Metrics::ID`. This should be called when
## a script has measured some point value and is ready to increment the
## counters.
##
## id: The metric ID that the data represents.
##
## index: The metric index that the value is to be added to.
##
## increment: How much to increment the counter by.
global add_data: function(id: ID, index: Index, increment: count);
## Helper function to represent a :bro:type:`Metrics::Index` value as
## a simple string
##
## index: The metric index that is to be converted into a string.
##
## Returns: A string reprentation of the metric index.
global index2str: function(index: Index): string;
## Event that is used to "finish" metrics and adapt the metrics
## framework for clustered or non-clustered usage.
##
## ..note: This is primarily intended for internal use.
global log_it: event(filter: Filter);
## Event to access metrics records as they are passed to the logging framework.
global log_metrics: event(rec: Info);
## Type to store a table of metrics values. Interal use only!
type MetricTable: table[Index] of count &default=0;
}
redef record Notice::Info += {
metric_index: Index &log &optional;
};
global metric_filters: table[ID] of vector of Filter = table();
global filter_store: table[ID, string] of Filter = table();
# This is indexed by metric ID and stream filter name.
global store: table[ID, string] of MetricTable = table() &default=table();
# This function checks if a threshold has been crossed and generates a
# notice if it has. It is also used as a method to implement
# mid-break-interval threshold crossing detection for cluster deployments.
global check_notice: function(filter: Filter, index: Index, val: count): bool;
# This is hook for watching thresholds being crossed. It is called whenever
# index values are updated and the new val is given as the `val` argument.
global data_added: function(filter: Filter, index: Index, val: count);
# This stores the current threshold index for filters using the
# $notice_threshold and $notice_thresholds elements.
global thresholds: table[ID, string, Index] of count = {} &create_expire=renotice_interval &default=0;
event bro_init() &priority=5
{
Log::create_stream(Metrics::LOG, [$columns=Info, $ev=log_metrics]);
}
function index2str(index: Index): string
{
local out = "";
if ( index?$host )
out = fmt("%shost=%s", out, index$host);
if ( index?$network )
out = fmt("%s%snetwork=%s", out, |out|==0 ? "" : ", ", index$network);
if ( index?$str )
out = fmt("%s%sstr=%s", out, |out|==0 ? "" : ", ", index$str);
return fmt("metric_index(%s)", out);
}
function write_log(ts: time, filter: Filter, data: MetricTable)
{
for ( index in data )
{
local val = data[index];
local m: Info = [$ts=ts,
$metric_id=filter$id,
$filter_name=filter$name,
$index=index,
$value=val];
if ( filter$log )
Log::write(Metrics::LOG, m);
}
}
function reset(filter: Filter)
{
store[filter$id, filter$name] = table();
}
function add_filter(id: ID, filter: Filter)
{
if ( filter?$aggregation_table && filter?$aggregation_mask )
{
print "INVALID Metric filter: Defined $aggregation_table and $aggregation_mask.";
return;
}
if ( [id, filter$name] in store )
{
print fmt("INVALID Metric filter: Filter with name \"%s\" already exists.", filter$name);
return;
}
if ( filter?$notice_threshold && filter?$notice_thresholds )
{
print "INVALID Metric filter: Defined both $notice_threshold and $notice_thresholds";
return;
}
if ( ! filter?$id )
filter$id = id;
if ( id !in metric_filters )
metric_filters[id] = vector();
metric_filters[id][|metric_filters[id]|] = filter;
filter_store[id, filter$name] = filter;
store[id, filter$name] = table();
schedule filter$break_interval { Metrics::log_it(filter) };
}
function add_data(id: ID, index: Index, increment: count)
{
if ( id !in metric_filters )
return;
local filters = metric_filters[id];
# Try to add the data to all of the defined filters for the metric.
for ( filter_id in filters )
{
local filter = filters[filter_id];
# If this filter has a predicate, run the predicate and skip this
# index if the predicate return false.
if ( filter?$pred && ! filter$pred(index) )
next;
if ( index?$host )
{
if ( filter?$aggregation_mask )
{
index$network = mask_addr(index$host, filter$aggregation_mask);
delete index$host;
}
else if ( filter?$aggregation_table )
{
# Don't add the data if the aggregation table doesn't include
# the given host address.
if ( index$host !in filter$aggregation_table )
return;
index$network = filter$aggregation_table[index$host];
delete index$host;
}
}
local metric_tbl = store[id, filter$name];
if ( index !in metric_tbl )
metric_tbl[index] = 0;
metric_tbl[index] += increment;
data_added(filter, index, metric_tbl[index]);
}
}
function check_notice(filter: Filter, index: Index, val: count): bool
{
if ( (filter?$notice_threshold &&
[filter$id, filter$name, index] !in thresholds &&
val >= filter$notice_threshold) ||
(filter?$notice_thresholds &&
|filter$notice_thresholds| <= thresholds[filter$id, filter$name, index] &&
val >= filter$notice_thresholds[thresholds[filter$id, filter$name, index]]) )
return T;
else
return F;
}
function do_notice(filter: Filter, index: Index, val: count)
{
# We include $peer_descr here because the a manager count have actually
# generated the notice even though the current remote peer for the event
# calling this could be a worker if this is running as a cluster.
local n: Notice::Info = [$note=filter$note,
$n=val,
$metric_index=index,
$peer_descr=peer_description];
n$msg = fmt("Threshold crossed by %s %d/%d", index2str(index), val, filter$notice_threshold);
if ( index?$str )
n$sub = index$str;
if ( index?$host )
n$src = index$host;
# TODO: not sure where to put the network yet.
NOTICE(n);
# This just needs set to some value so that it doesn't refire the
# notice until it expires from the table or it crosses the next
# threshold in the case of vectors of thresholds.
++thresholds[filter$id, filter$name, index];
}

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@load ./main
module Metrics;
event Metrics::log_it(filter: Filter)
{
local id = filter$id;
local name = filter$name;
write_log(network_time(), filter, store[id, name]);
reset(filter);
schedule filter$break_interval { Metrics::log_it(filter) };
}
function data_added(filter: Filter, index: Index, val: count)
{
if ( check_notice(filter, index, val) )
do_notice(filter, index, val);
}

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@load ./main
@load ./plugins
# The cluster framework must be loaded first.
@load base/frameworks/cluster

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##! This implements transparent cluster support for the SumStats framework.
##! Do not load this file directly. It's only meant to be loaded automatically
##! and will be depending on if the cluster framework has been enabled.
##! The goal of this script is to make sumstats calculation completely and
##! transparently automated when running on a cluster.
@load base/frameworks/cluster
@load ./main
module SumStats;
export {
## Allows a user to decide how large of result groups the workers should transmit
## values for cluster stats aggregation.
const cluster_send_in_groups_of = 50 &redef;
## The percent of the full threshold value that needs to be met on a single worker
## for that worker to send the value to its manager in order for it to request a
## global view for that value. There is no requirement that the manager requests
## a global view for the key since it may opt not to if it requested a global view
## for the key recently.
const cluster_request_global_view_percent = 0.2 &redef;
## This is to deal with intermediate update overload. A manager will only allow
## this many intermediate update requests to the workers to be inflight at any
## given time. Requested intermediate updates are currently thrown out and not
## performed. In practice this should hopefully have a minimal effect.
const max_outstanding_global_views = 10 &redef;
## Intermediate updates can cause overload situations on very large clusters. This
## option may help reduce load and correct intermittent problems. The goal for this
## option is also meant to be temporary.
const enable_intermediate_updates = T &redef;
## Event sent by the manager in a cluster to initiate the collection of values for
## a sumstat.
global cluster_ss_request: event(uid: string, ssid: string);
## Event sent by nodes that are collecting sumstats after receiving a request for
## the sumstat from the manager.
global cluster_ss_response: event(uid: string, ssid: string, data: ResultTable, done: bool);
## This event is sent by the manager in a cluster to initiate the collection of
## a single key value from a sumstat. It's typically used to get intermediate
## updates before the break interval triggers to speed detection of a value
## crossing a threshold.
global cluster_key_request: event(uid: string, ssid: string, key: Key);
## This event is sent by nodes in response to a
## :bro:id:`SumStats::cluster_key_request` event.
global cluster_key_response: event(uid: string, ssid: string, key: Key, result: Result);
## This is sent by workers to indicate that they crossed the percent
## of the current threshold by the percentage defined globally in
## :bro:id:`SumStats::cluster_request_global_view_percent`
global cluster_key_intermediate_response: event(ssid: string, key: SumStats::Key);
## This event is scheduled internally on workers to send result chunks.
global send_data: event(uid: string, ssid: string, data: ResultTable);
## This event is generated when a threshold is crossed.
global cluster_threshold_crossed: event(ssid: string, key: SumStats::Key, thold: Thresholding);
}
# Add events to the cluster framework to make this work.
redef Cluster::manager2worker_events += /SumStats::cluster_(ss_request|key_request|threshold_crossed)/;
redef Cluster::manager2worker_events += /SumStats::thresholds_reset/;
redef Cluster::worker2manager_events += /SumStats::cluster_(ss_response|key_response|key_intermediate_response)/;
@if ( Cluster::local_node_type() != Cluster::MANAGER )
# This variable is maintained to know what keys have recently sent as
# intermediate updates so they don't overwhelm their manager. The count that is
# yielded is the number of times the percentage threshold has been crossed and
# an intermediate result has been received.
global recent_global_view_keys: table[string, Key] of count &create_expire=1min &default=0;
event bro_init() &priority=-100
{
# The manager is the only host allowed to track these.
stats_store = table();
reducer_store = table();
}
# This is done on all non-manager node types in the event that a sumstat is
# being collected somewhere other than a worker.
function data_added(ss: SumStat, key: Key, result: Result)
{
# If an intermediate update for this value was sent recently, don't send
# it again.
if ( [ss$id, key] in recent_global_view_keys )
return;
# If val is 5 and global view % is 0.1 (10%), pct_val will be 50. If that
# crosses the full threshold then it's a candidate to send as an
# intermediate update.
if ( enable_intermediate_updates &&
check_thresholds(ss, key, result, cluster_request_global_view_percent) )
{
# kick off intermediate update
event SumStats::cluster_key_intermediate_response(ss$id, key);
++recent_global_view_keys[ss$id, key];
}
}
event SumStats::send_data(uid: string, ssid: string, data: ResultTable)
{
#print fmt("WORKER %s: sending data for uid %s...", Cluster::node, uid);
local local_data: ResultTable = table();
local num_added = 0;
for ( key in data )
{
local_data[key] = data[key];
delete data[key];
# Only send cluster_send_in_groups_of at a time. Queue another
# event to send the next group.
if ( cluster_send_in_groups_of == ++num_added )
break;
}
local done = F;
# If data is empty, this sumstat is done.
if ( |data| == 0 )
done = T;
# Note: copy is needed to compensate serialization caching issue. This should be
# changed to something else later.
event SumStats::cluster_ss_response(uid, ssid, copy(local_data), done);
if ( ! done )
schedule 0.01 sec { SumStats::send_data(uid, ssid, data) };
}
event SumStats::cluster_ss_request(uid: string, ssid: string)
{
#print fmt("WORKER %s: received the cluster_ss_request event for %s.", Cluster::node, id);
# Initiate sending all of the data for the requested stats.
if ( ssid in result_store )
event SumStats::send_data(uid, ssid, result_store[ssid]);
else
event SumStats::send_data(uid, ssid, table());
# Lookup the actual sumstats and reset it, the reference to the data
# currently stored will be maintained internally by the send_data event.
if ( ssid in stats_store )
reset(stats_store[ssid]);
}
event SumStats::cluster_key_request(uid: string, ssid: string, key: Key)
{
if ( ssid in result_store && key in result_store[ssid] )
{
#print fmt("WORKER %s: received the cluster_key_request event for %s=%s.", Cluster::node, key2str(key), data);
# Note: copy is needed to compensate serialization caching issue. This should be
# changed to something else later.
event SumStats::cluster_key_response(uid, ssid, key, copy(result_store[ssid][key]));
}
else
{
# We need to send an empty response if we don't have the data so that the manager
# can know that it heard back from all of the workers.
event SumStats::cluster_key_response(uid, ssid, key, table());
}
}
event SumStats::cluster_threshold_crossed(ssid: string, key: SumStats::Key, thold: Thresholding)
{
if ( ssid !in threshold_tracker )
threshold_tracker[ssid] = table();
threshold_tracker[ssid][key] = thold;
}
event SumStats::thresholds_reset(ssid: string)
{
threshold_tracker[ssid] = table();
}
@endif
@if ( Cluster::local_node_type() == Cluster::MANAGER )
# This variable is maintained by manager nodes as they collect and aggregate
# results.
# Index on a uid.
global stats_results: table[string] of ResultTable &read_expire=1min;
# This variable is maintained by manager nodes to track how many "dones" they
# collected per collection unique id. Once the number of results for a uid
# matches the number of peer nodes that results should be coming from, the
# result is written out and deleted from here.
# Indexed on a uid.
# TODO: add an &expire_func in case not all results are received.
global done_with: table[string] of count &read_expire=1min &default=0;
# This variable is maintained by managers to track intermediate responses as
# they are getting a global view for a certain key.
# Indexed on a uid.
global key_requests: table[string] of Result &read_expire=1min;
# This variable is maintained by managers to prevent overwhelming communication due
# to too many intermediate updates. Each sumstat is tracked separately so that
# one won't overwhelm and degrade other quieter sumstats.
# Indexed on a sumstat id.
global outstanding_global_views: table[string] of count &default=0;
const zero_time = double_to_time(0.0);
# Managers handle logging.
event SumStats::finish_epoch(ss: SumStat)
{
if ( network_time() > zero_time )
{
#print fmt("%.6f MANAGER: breaking %s sumstat for %s sumstat", network_time(), ss$name, ss$id);
local uid = unique_id("");
if ( uid in stats_results )
delete stats_results[uid];
stats_results[uid] = table();
# Request data from peers.
event SumStats::cluster_ss_request(uid, ss$id);
}
# Schedule the next finish_epoch event.
schedule ss$epoch { SumStats::finish_epoch(ss) };
}
# This is unlikely to be called often, but it's here in
# case there are sumstats being collected by managers.
function data_added(ss: SumStat, key: Key, result: Result)
{
if ( check_thresholds(ss, key, result, 1.0) )
{
threshold_crossed(ss, key, result);
event SumStats::cluster_threshold_crossed(ss$id, key, threshold_tracker[ss$id][key]);
}
}
event SumStats::cluster_key_response(uid: string, ssid: string, key: Key, result: Result)
{
#print fmt("%0.6f MANAGER: receiving key data from %s - %s=%s", network_time(), get_event_peer()$descr, key2str(key), result);
# We only want to try and do a value merge if there are actually measured datapoints
# in the Result.
if ( uid in key_requests )
key_requests[uid] = compose_results(key_requests[uid], result);
else
key_requests[uid] = result;
# Mark that a worker is done.
++done_with[uid];
#print fmt("worker_count:%d :: done_with:%d", Cluster::worker_count, done_with[uid]);
if ( Cluster::worker_count == done_with[uid] )
{
local ss = stats_store[ssid];
local ir = key_requests[uid];
if ( check_thresholds(ss, key, ir, 1.0) )
{
threshold_crossed(ss, key, ir);
event SumStats::cluster_threshold_crossed(ss$id, key, threshold_tracker[ss$id][key]);
}
delete done_with[uid];
delete key_requests[uid];
# Check that there is an outstanding view before subtracting.
if ( outstanding_global_views[ssid] > 0 )
--outstanding_global_views[ssid];
}
}
# Managers handle intermediate updates here.
event SumStats::cluster_key_intermediate_response(ssid: string, key: Key)
{
#print fmt("MANAGER: receiving intermediate key data from %s", get_event_peer()$descr);
#print fmt("MANAGER: requesting key data for %s", key2str(key));
if ( ssid in outstanding_global_views &&
|outstanding_global_views[ssid]| > max_outstanding_global_views )
{
# Don't do this intermediate update. Perhaps at some point in the future
# we will queue and randomly select from these ignored intermediate
# update requests.
return;
}
++outstanding_global_views[ssid];
local uid = unique_id("");
event SumStats::cluster_key_request(uid, ssid, key);
}
event SumStats::cluster_ss_response(uid: string, ssid: string, data: ResultTable, done: bool)
{
#print fmt("MANAGER: receiving results from %s", get_event_peer()$descr);
# Mark another worker as being "done" for this uid.
if ( done )
++done_with[uid];
local local_data = stats_results[uid];
local ss = stats_store[ssid];
for ( key in data )
{
if ( key in local_data )
local_data[key] = compose_results(local_data[key], data[key]);
else
local_data[key] = data[key];
# If a stat is done being collected, thresholds for each key
# need to be checked so we're doing it here to avoid doubly
# iterating over each key.
if ( Cluster::worker_count == done_with[uid] )
{
if ( check_thresholds(ss, key, local_data[key], 1.0) )
{
threshold_crossed(ss, key, local_data[key]);
event SumStats::cluster_threshold_crossed(ss$id, key, threshold_tracker[ss$id][key]);
}
}
}
# If the data has been collected from all peers, we are done and ready to finish.
if ( Cluster::worker_count == done_with[uid] )
{
if ( ss?$epoch_finished )
ss$epoch_finished(local_data);
# Clean up
delete stats_results[uid];
delete done_with[uid];
# Not sure I need to reset the sumstat on the manager.
reset(ss);
}
}
event remote_connection_handshake_done(p: event_peer) &priority=5
{
send_id(p, "SumStats::stats_store");
send_id(p, "SumStats::reducer_store");
}
@endif

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##! The summary statistics framework provides a way to
##! summarize large streams of data into simple reduced
##! measurements.
module SumStats;
export {
## The various calculations are all defined as plugins.
type Calculation: enum {
PLACEHOLDER
};
## Represents a thing which is having summarization
## results collected for it.
type Key: record {
## A non-address related summarization or a sub-key for
## an address based summarization. An example might be
## successful SSH connections by client IP address
## where the client string would be the key value.
## Another example might be number of HTTP requests to
## a particular value in a Host header. This is an
## example of a non-host based metric since multiple
## IP addresses could respond for the same Host
## header value.
str: string &optional;
## Host is the value to which this metric applies.
host: addr &optional;
};
## Represents data being added for a single observation.
## Only supply a single field at a time!
type Observation: record {
## Count value.
num: count &optional;
## Double value.
dbl: double &optional;
## String value.
str: string &optional;
};
type Reducer: record {
## Observation stream identifier for the reducer
## to attach to.
stream: string;
## The calculations to perform on the data points.
apply: set[Calculation];
## A predicate so that you can decide per key if you
## would like to accept the data being inserted.
pred: function(key: SumStats::Key, obs: SumStats::Observation): bool &optional;
## A function to normalize the key. This can be used to aggregate or
## normalize the entire key.
normalize_key: function(key: SumStats::Key): Key &optional;
};
## Value calculated for an observation stream fed into a reducer.
## Most of the fields are added by plugins.
type ResultVal: record {
## The time when the first observation was added to
## this result value.
begin: time;
## The time when the last observation was added to
## this result value.
end: time;
## The number of observations received.
num: count &default=0;
};
## Type to store results for multiple reducers.
type Result: table[string] of ResultVal;
## Type to store a table of sumstats results indexed
## by keys.
type ResultTable: table[Key] of Result;
## SumStats represent an aggregation of reducers along with
## mechanisms to handle various situations like the epoch ending
## or thresholds being crossed.
##
## It's best to not access any global state outside
## of the variables given to the callbacks because there
## is no assurance provided as to where the callbacks
## will be executed on clusters.
type SumStat: record {
## The interval at which this filter should be "broken"
## and the '$epoch_finished' callback called. The
## results are also reset at this time so any threshold
## based detection needs to be set to a
## value that should be expected to happen within
## this epoch.
epoch: interval;
## The reducers for the SumStat
reducers: set[Reducer];
## Provide a function to calculate a value from the
## :bro:see:`Result` structure which will be used
## for thresholding.
## This is required if a $threshold value is given.
threshold_val: function(key: SumStats::Key, result: SumStats::Result): count &optional;
## The threshold value for calling the
## $threshold_crossed callback.
threshold: count &optional;
## A series of thresholds for calling the
## $threshold_crossed callback.
threshold_series: vector of count &optional;
## A callback that is called when a threshold is crossed.
threshold_crossed: function(key: SumStats::Key, result: SumStats::Result) &optional;
## A callback with the full collection of Results for
## this SumStat.
epoch_finished: function(rt: SumStats::ResultTable) &optional;
};
## Create a summary statistic.
global create: function(ss: SumStats::SumStat);
## Add data into an observation stream. This should be
## called when a script has measured some point value.
##
## id: The observation stream identifier that the data
## point represents.
##
## key: The key that the value is related to.
##
## obs: The data point to send into the stream.
global observe: function(id: string, key: SumStats::Key, obs: SumStats::Observation);
## This record is primarily used for internal threshold tracking.
type Thresholding: record {
# Internal use only. Indicates if a simple threshold was already crossed.
is_threshold_crossed: bool &default=F;
# Internal use only. Current key for threshold series.
threshold_series_index: count &default=0;
};
## This event is generated when thresholds are reset for a SumStat.
##
## ssid: SumStats ID that thresholds were reset for.
global thresholds_reset: event(ssid: string);
## Helper function to represent a :bro:type:`SumStats::Key` value as
## a simple string.
##
## key: The metric key that is to be converted into a string.
##
## Returns: A string representation of the metric key.
global key2str: function(key: SumStats::Key): string;
}
redef record Reducer += {
# Internal use only. Provides a reference back to the related SumStats by it's ID.
sid: string &optional;
};
# Internal use only. For tracking thresholds per sumstat and key.
global threshold_tracker: table[string] of table[Key] of Thresholding &optional;
redef record SumStat += {
# Internal use only (mostly for cluster coherency).
id: string &optional;
};
# Store of sumstats indexed on the sumstat id.
global stats_store: table[string] of SumStat = table();
# Store of reducers indexed on the data point stream id.
global reducer_store: table[string] of set[Reducer] = table();
# Store of results indexed on the measurement id.
global result_store: table[string] of ResultTable = table();
# Store of threshold information.
global thresholds_store: table[string, Key] of bool = table();
# This is called whenever key values are updated and the new val is given as the
# `val` argument. It's only prototyped here because cluster and non-cluster have
# separate implementations.
global data_added: function(ss: SumStat, key: Key, result: Result);
# Prototype the hook point for plugins to do calculations.
global observe_hook: hook(r: Reducer, val: double, data: Observation, rv: ResultVal);
# Prototype the hook point for plugins to initialize any result values.
global init_resultval_hook: hook(r: Reducer, rv: ResultVal);
# Prototype the hook point for plugins to merge Results.
global compose_resultvals_hook: hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal);
# Event that is used to "finish" measurements and adapt the measurement
# framework for clustered or non-clustered usage.
global finish_epoch: event(ss: SumStat);
function key2str(key: Key): string
{
local out = "";
if ( key?$host )
out = fmt("%shost=%s", out, key$host);
if ( key?$str )
out = fmt("%s%sstr=%s", out, |out|==0 ? "" : ", ", key$str);
return fmt("sumstats_key(%s)", out);
}
function init_resultval(r: Reducer): ResultVal
{
local rv: ResultVal = [$begin=network_time(), $end=network_time()];
hook init_resultval_hook(r, rv);
return rv;
}
function compose_resultvals(rv1: ResultVal, rv2: ResultVal): ResultVal
{
local result: ResultVal;
result$begin = (rv1$begin < rv2$begin) ? rv1$begin : rv2$begin;
result$end = (rv1$end > rv2$end) ? rv1$end : rv2$end;
result$num = rv1$num + rv2$num;
# Run the plugin composition hooks.
hook compose_resultvals_hook(result, rv1, rv2);
return result;
}
function compose_results(r1: Result, r2: Result): Result
{
local result: Result = table();
if ( |r1| > |r2| )
{
for ( data_id in r1 )
{
if ( data_id in r2 )
result[data_id] = compose_resultvals(r1[data_id], r2[data_id]);
else
result[data_id] = r1[data_id];
}
}
else
{
for ( data_id in r2 )
{
if ( data_id in r1 )
result[data_id] = compose_resultvals(r1[data_id], r2[data_id]);
else
result[data_id] = r2[data_id];
}
}
return result;
}
function reset(ss: SumStat)
{
if ( ss$id in result_store )
delete result_store[ss$id];
result_store[ss$id] = table();
if ( ss?$threshold || ss?$threshold_series )
{
threshold_tracker[ss$id] = table();
event SumStats::thresholds_reset(ss$id);
}
}
function create(ss: SumStat)
{
if ( (ss?$threshold || ss?$threshold_series) && ! ss?$threshold_val )
{
Reporter::error("SumStats given a threshold with no $threshold_val function");
}
if ( ! ss?$id )
ss$id=unique_id("");
threshold_tracker[ss$id] = table();
stats_store[ss$id] = ss;
for ( reducer in ss$reducers )
{
reducer$sid = ss$id;
if ( reducer$stream !in reducer_store )
reducer_store[reducer$stream] = set();
add reducer_store[reducer$stream][reducer];
}
reset(ss);
schedule ss$epoch { SumStats::finish_epoch(ss) };
}
function observe(id: string, key: Key, obs: Observation)
{
if ( id !in reducer_store )
return;
# Try to add the data to all of the defined reducers.
for ( r in reducer_store[id] )
{
if ( r?$normalize_key )
key = r$normalize_key(copy(key));
# If this reducer has a predicate, run the predicate
# and skip this key if the predicate return false.
if ( r?$pred && ! r$pred(key, obs) )
next;
local ss = stats_store[r$sid];
# If there is a threshold and no epoch_finished callback
# we don't need to continue counting since the data will
# never be accessed. This was leading
# to some state management issues when measuring
# uniqueness.
# NOTE: this optimization could need removed in the
# future if on demand access is provided to the
# SumStats results.
if ( ! ss?$epoch_finished &&
r$sid in threshold_tracker &&
key in threshold_tracker[r$sid] &&
( ss?$threshold &&
threshold_tracker[r$sid][key]$is_threshold_crossed ) ||
( ss?$threshold_series &&
threshold_tracker[r$sid][key]$threshold_series_index+1 == |ss$threshold_series| ) )
next;
if ( r$sid !in result_store )
result_store[ss$id] = table();
local results = result_store[r$sid];
if ( key !in results )
results[key] = table();
local result = results[key];
if ( id !in result )
result[id] = init_resultval(r);
local result_val = result[id];
++result_val$num;
# Continually update the $end field.
result_val$end=network_time();
# If a string was given, fall back to 1.0 as the value.
local val = 1.0;
if ( obs?$num || obs?$dbl )
val = obs?$dbl ? obs$dbl : obs$num;
hook observe_hook(r, val, obs, result_val);
data_added(ss, key, result);
}
}
# This function checks if a threshold has been crossed. It is also used as a method to implement
# mid-break-interval threshold crossing detection for cluster deployments.
function check_thresholds(ss: SumStat, key: Key, result: Result, modify_pct: double): bool
{
if ( ! (ss?$threshold || ss?$threshold_series) )
return F;
# Add in the extra ResultVals to make threshold_vals easier to write.
if ( |ss$reducers| != |result| )
{
for ( reducer in ss$reducers )
{
if ( reducer$stream !in result )
result[reducer$stream] = init_resultval(reducer);
}
}
local watch = ss$threshold_val(key, result);
if ( modify_pct < 1.0 && modify_pct > 0.0 )
watch = double_to_count(floor(watch/modify_pct));
if ( ss$id !in threshold_tracker )
threshold_tracker[ss$id] = table();
local t_tracker = threshold_tracker[ss$id];
if ( key !in t_tracker )
{
local ttmp: Thresholding;
t_tracker[key] = ttmp;
}
local tt = t_tracker[key];
if ( ss?$threshold && ! tt$is_threshold_crossed && watch >= ss$threshold )
{
# Value crossed the threshold.
return T;
}
if ( ss?$threshold_series &&
|ss$threshold_series| >= tt$threshold_series_index &&
watch >= ss$threshold_series[tt$threshold_series_index] )
{
# A threshold series was given and the value crossed the next
# value in the series.
return T;
}
return F;
}
function threshold_crossed(ss: SumStat, key: Key, result: Result)
{
# If there is no callback, there is no point in any of this.
if ( ! ss?$threshold_crossed )
return;
# Add in the extra ResultVals to make threshold_crossed callbacks easier to write.
if ( |ss$reducers| != |result| )
{
for ( reducer in ss$reducers )
{
if ( reducer$stream !in result )
result[reducer$stream] = init_resultval(reducer);
}
}
ss$threshold_crossed(key, result);
local tt = threshold_tracker[ss$id][key];
tt$is_threshold_crossed = T;
# Bump up to the next threshold series index if a threshold series is being used.
if ( ss?$threshold_series )
++tt$threshold_series_index;
}

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@load ./main
module SumStats;
event SumStats::finish_epoch(ss: SumStat)
{
if ( ss$id in result_store )
{
local data = result_store[ss$id];
if ( ss?$epoch_finished )
ss$epoch_finished(data);
reset(ss);
}
schedule ss$epoch { SumStats::finish_epoch(ss) };
}
function data_added(ss: SumStat, key: Key, result: Result)
{
if ( check_thresholds(ss, key, result, 1.0) )
threshold_crossed(ss, key, result);
}

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@load ./average
@load ./max
@load ./min
@load ./sample
@load ./std-dev
@load ./sum
@load ./unique
@load ./variance

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@load base/frameworks/sumstats/main
module SumStats;
export {
redef enum Calculation += {
## Calculate the average of the values.
AVERAGE
};
redef record ResultVal += {
## For numeric data, this calculates the average of all values.
average: double &optional;
};
}
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( AVERAGE in r$apply )
{
if ( ! rv?$average )
rv$average = val;
else
rv$average += (val - rv$average) / rv$num;
}
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
if ( rv1?$average && rv2?$average )
result$average = ((rv1$average*rv1$num) + (rv2$average*rv2$num))/(rv1$num+rv2$num);
else if ( rv1?$average )
result$average = rv1$average;
else if ( rv2?$average )
result$average = rv2$average;
}

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@load base/frameworks/sumstats/main
module SumStats;
export {
redef enum Calculation += {
## Find the maximum value.
MAX
};
redef record ResultVal += {
## For numeric data, this tracks the maximum value given.
max: double &optional;
};
}
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( MAX in r$apply )
{
if ( ! rv?$max )
rv$max = val;
else if ( val > rv$max )
rv$max = val;
}
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
if ( rv1?$max && rv2?$max )
result$max = (rv1$max > rv2$max) ? rv1$max : rv2$max;
else if ( rv1?$max )
result$max = rv1$max;
else if ( rv2?$max )
result$max = rv2$max;
}

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@load base/frameworks/sumstats/main
module SumStats;
export {
redef enum Calculation += {
## Find the minimum value.
MIN
};
redef record ResultVal += {
## For numeric data, this tracks the minimum value given.
min: double &optional;
};
}
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( MIN in r$apply )
{
if ( ! rv?$min )
rv$min = val;
else if ( val < rv$min )
rv$min = val;
}
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
if ( rv1?$min && rv2?$min )
result$min = (rv1$min < rv2$min) ? rv1$min : rv2$min;
else if ( rv1?$min )
result$min = rv1$min;
else if ( rv2?$min )
result$min = rv2$min;
}

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@load base/frameworks/sumstats/main
@load base/utils/queue
module SumStats;
export {
redef record Reducer += {
## A number of sample Observations to collect.
samples: count &default=0;
};
redef record ResultVal += {
## This is the queue where samples are maintained. Use the
## :bro:see:`SumStats::get_samples` function to get a vector of the samples.
samples: Queue::Queue &optional;
};
## Get a vector of sample Observation values from a ResultVal.
global get_samples: function(rv: ResultVal): vector of Observation;
}
function get_samples(rv: ResultVal): vector of Observation
{
local s: vector of Observation = vector();
if ( rv?$samples )
Queue::get_vector(rv$samples, s);
return s;
}
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( r$samples > 0 )
{
if ( ! rv?$samples )
rv$samples = Queue::init([$max_len=r$samples]);
Queue::put(rv$samples, obs);
}
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
# Merge $samples
if ( rv1?$samples && rv2?$samples )
result$samples = Queue::merge(rv1$samples, rv2$samples);
else if ( rv1?$samples )
result$samples = rv1$samples;
else if ( rv2?$samples )
result$samples = rv2$samples;
}

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@load base/frameworks/sumstats/main
@load ./variance
module SumStats;
export {
redef enum Calculation += {
## Find the standard deviation of the values.
STD_DEV
};
redef record ResultVal += {
## For numeric data, this calculates the standard deviation.
std_dev: double &default=0.0;
};
}
function calc_std_dev(rv: ResultVal)
{
if ( rv?$variance )
rv$std_dev = sqrt(rv$variance);
}
# This depends on the variance plugin which uses priority -5
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal) &priority=-10
{
if ( STD_DEV in r$apply )
calc_std_dev(rv);
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal) &priority=-10
{
calc_std_dev(result);
}

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@load base/frameworks/sumstats/main
module SumStats;
export {
redef enum Calculation += {
## Sums the values given. For string values,
## this will be the number of strings given.
SUM
};
redef record ResultVal += {
## For numeric data, this tracks the sum of all values.
sum: double &default=0.0;
};
type threshold_function: function(key: SumStats::Key, result: SumStats::Result): count;
global sum_threshold: function(data_id: string): threshold_function;
}
function sum_threshold(data_id: string): threshold_function
{
return function(key: SumStats::Key, result: SumStats::Result): count
{
print fmt("data_id: %s", data_id);
print result;
return double_to_count(result[data_id]$sum);
};
}
hook init_resultval_hook(r: Reducer, rv: ResultVal)
{
if ( SUM in r$apply && ! rv?$sum )
rv$sum = 0;
}
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( SUM in r$apply )
rv$sum += val;
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
if ( rv1?$sum || rv2?$sum )
{
result$sum = rv1?$sum ? rv1$sum : 0;
if ( rv2?$sum )
result$sum += rv2$sum;
}
}

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@load base/frameworks/sumstats/main
module SumStats;
export {
redef enum Calculation += {
## Calculate the number of unique values.
UNIQUE
};
redef record ResultVal += {
## If cardinality is being tracked, the number of unique
## items is tracked here.
unique: count &default=0;
};
}
redef record ResultVal += {
# Internal use only. This is not meant to be publically available
# because we don't want to trust that we can inspect the values
# since we will like move to a probalistic data structure in the future.
# TODO: in the future this will optionally be a hyperloglog structure
unique_vals: set[Observation] &optional;
};
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
{
if ( UNIQUE in r$apply )
{
if ( ! rv?$unique_vals )
rv$unique_vals=set();
add rv$unique_vals[obs];
rv$unique = |rv$unique_vals|;
}
}
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
{
if ( rv1?$unique_vals || rv2?$unique_vals )
{
if ( rv1?$unique_vals )
result$unique_vals = rv1$unique_vals;
if ( rv2?$unique_vals )
if ( ! result?$unique_vals )
result$unique_vals = rv2$unique_vals;
else
for ( val2 in rv2$unique_vals )
add result$unique_vals[val2];
result$unique = |result$unique_vals|;
}
}

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@load base/frameworks/sumstats/main
@load ./average
module SumStats;
export {
redef enum Calculation += {
## Find the variance of the values.
VARIANCE
};
redef record ResultVal += {
## For numeric data, this calculates the variance.
variance: double &optional;
};
}
redef record ResultVal += {
# Internal use only. Used for incrementally calculating variance.
prev_avg: double &optional;
# Internal use only. For calculating incremental variance.
var_s: double &default=0.0;
};
function calc_variance(rv: ResultVal)
{
rv$variance = (rv$num > 1) ? rv$var_s/(rv$num-1) : 0.0;
}
# Reduced priority since this depends on the average
hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal) &priority=-5
{
if ( VARIANCE in r$apply )
{
if ( rv$num > 1 )
rv$var_s += ((val - rv$prev_avg) * (val - rv$average));
calc_variance(rv);
rv$prev_avg = rv$average;
}
}
# Reduced priority since this depends on the average
hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal) &priority=-5
{
if ( rv1?$var_s && rv1?$average &&
rv2?$var_s && rv2?$average )
{
local rv1_avg_sq = (rv1$average - result$average);
rv1_avg_sq = rv1_avg_sq*rv1_avg_sq;
local rv2_avg_sq = (rv2$average - result$average);
rv2_avg_sq = rv2_avg_sq*rv2_avg_sq;
result$var_s = rv1$num*(rv1$var_s/rv1$num + rv1_avg_sq) + rv2$num*(rv2$var_s/rv2$num + rv2_avg_sq);
}
else if ( rv1?$var_s )
result$var_s = rv1$var_s;
else if ( rv2?$var_s )
result$var_s = rv2$var_s;
if ( rv1?$prev_avg && rv2?$prev_avg )
result$prev_avg = ((rv1$prev_avg*rv1$num) + (rv2$prev_avg*rv2$num))/(rv1$num+rv2$num);
else if ( rv1?$prev_avg )
result$prev_avg = rv1$prev_avg;
else if ( rv2?$prev_avg )
result$prev_avg = rv2$prev_avg;
calc_variance(result);
}