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//! Statistics generator for [`slog`].
//!
//! This crate allows for statistics - counters, gauges, and bucket counters - to be automatically
//! calculated and reported based on logged events. The logged events MUST implement the
//! [`ExtLoggable`] trait.
//!
//! To support this, the [`slog-extlog-derive`] crate can be used to link logs to a specific
//! statistic. This generates fast, compile-time checking for statistics updates at the point
//! of logging.
//!
//! Users should use the [`define_stats`] macro to list their statistics. They can then pass the
//! list (along with stats from any dependencies) to a [`StatisticsLogger`] wrapping an
//! [`slog::Logger`]. The statistics trigger function on the `ExtLoggable` objects then triggers
//! statistic updates based on logged values.
//!
//! Library users should export the result of `define_stats!`, so that binary developers can
//! track the set of stats from all dependent crates in a single tracker.
//!
//! Triggers should be added to [`ExtLoggable`] objects using the [`slog-extlog-derive`] crate.
//!
//! [`ExtLoggable`]: ../trait.ExtLoggable.html
//! [`define_stats`]: ../macro.define_stats.html
//! [`slog::Logger`]: ../../slog/struct.Logger.html
//! [`slog`]: ../../slog/index.html
//! [`slog-extlog-derive`]: ../../slog_extlog_derive/index.html
//! [`StatisticsLogger`]: ./struct.StatisticsLogger.html
use std::collections::HashMap;
use std::fmt;
use std::ops::Deref;
use std::panic::RefUnwindSafe;
use std::sync::atomic::{AtomicIsize, Ordering};
use std::sync::Arc;
use std::sync::RwLock;
#[cfg(feature = "interval_logging")]
use std::time::Duration;
use slog::info;
//////////////////////////////////////////////////////
// Public types - stats definitions
//////////////////////////////////////////////////////
/// A configured statistic, defined in terms of the external logs that trigger it to change.
///
/// These definitions are provided at start of day to populate the tracker.
///
/// These should NOT be constructed directly but by using the
/// [`define_stats`](./macro.define_stats.html) macro.
///
pub trait StatDefinition: fmt::Debug {
/// The name of this metric. This name is reported in logs as the `metric_name` field.
fn name(&self) -> &'static str;
/// A human readable-description of the statistic, describing its meaning. When logged this
/// is the log message.
fn description(&self) -> &'static str;
/// The type of statistic.
fn stype(&self) -> StatType;
/// An optional list of field names to group the statistic by.
fn group_by(&self) -> Vec<&'static str>;
/// An optional set of numerical buckets to group the statistic by.
fn buckets(&self) -> Option<Buckets>;
}
/// A macro to define the statistics that can be tracked by the logger.
/// Use of this macro requires [`StatDefinition`](trait.StatDefinition.html) to be in scope.
///
/// All statistics should be defined by their library using this macro.
///
/// The syntax is as follows:
///
/// ```text
/// define_stats!{
/// STATS_LIST_NAME = {
/// StatName(Type, "Description", ["tag1", "tag2", ...]),
/// StatName2(...),
/// ...
/// }
/// }
/// ```
///
/// The `STATS_LIST_NAME` is then created as a vector of definitions that can be passed in as the
/// `stats` field on a `StatsConfig` object.
///
/// Each definition in the list has the format above, with the fields as follows.
///
/// - `StatName` is the externally-facing metric name.
/// - `Type` is the `StatType` of this statistic, for example `Counter`.
/// Must be a valid subtype of that enum.
/// - `Description` is a human readable description of the statistic. This will be logged as
/// the log message,
/// - The list of `tags` define field names to group the statistic by.
/// A non-empty list indicates that this statistic should be split into groups,
/// counting the stat separately for each different value of these fields that is seen.
/// These might be a remote hostname, say, or a tag field.
/// - If multiple tags are provided, the stat is counted separately for all distinct
/// combinations of tag values.
/// - Use of this feature should be avoided for fields that can take very many values, such as
/// a subscriber number, or for large numbers of tags - each tag name and seen value adds a
/// performance dip and a small memory overhead that is never freed.
/// - If the `Type` field is set to `BucketCounter`, then a `BucketMethod`, bucket label and bucket limits must
/// also be provided like so:
///
/// ```text
/// define_stats!{
/// STATS_LIST_NAME = {
/// StatName(BucketCounter, "Description", ["tag1", "tag2", ...], (BucketMethod, "bucket_label", [1, 2, 3, ...])),
/// StatName2(...),
/// ...
/// }
/// }
/// ```
///
/// - The `BucketMethod` determines how the stat will be sorted into numerical buckets and should
/// - be a subtype of that enum.
/// - The bucket limits should be a list of `i64` values, each representing the upper bound of
/// that bucket.
/// - The bucket label should describe what the buckets measure and should be distinct from the tags.
/// Each stat log will be labelled with the pair `(bucket_label, bucket_value)` in addition to the tags,
/// where `bucket_value` is the numerical value of the bucket the log falls into.
#[macro_export]
macro_rules! define_stats {
// Entry point - match each individual stat name and pass on the details for further parsing
($name:ident = {$($stat:ident($($details:tt),*)),*}) => {
/// A vector of stats that can be passed in as the `stats` field on a `StatsConfig` object.
pub static $name: $crate::stats::StatDefinitions = &[$(&$stat),*];
mod inner_stats {
$(
#[derive(Debug, Clone)]
// Prometheus metrics are snake_case, so allow non-camel-case types here.
#[allow(non_camel_case_types)]
pub struct $stat;
)*
}
$(
$crate::define_stats!{@single $stat, $($details),*}
)*
};
// `BucketCounter`s require a `BucketMethod`, bucket label and bucket limits
(@single $stat:ident, BucketCounter, $desc:expr, [$($tags:tt),*], ($bmethod:ident, $blabel:expr, [$($blimits:expr),*]) ) => {
$crate::define_stats!{@inner $stat, BucketCounter, $desc, $bmethod, $blabel, [$($tags),*], [$($blimits),*]}
};
// Non `BucketCounter` stat types
(@single $stat:ident, $stype:ident, $desc:expr, [$($tags:tt),*] ) => {
$crate::define_stats!{@inner $stat, $stype, $desc, Freq, "", [$($tags),*], []}
};
// Retained for backwards-compatibility
(@single $stat:ident, $stype:ident, $id:expr, $desc:expr, [$($tags:tt),*] ) => {
$crate::define_stats!{@inner $stat, $stype, $desc, Freq, "", [$($tags),*], []}
};
// Trait impl for StatDefinition
(@inner $stat:ident, $stype:ident, $desc:expr, $bmethod:ident, $blabel:expr, [$($tags:tt),*], [$($blimits:expr),*]) => {
// Suppress the warning about cases - this value is never going to be seen
#[allow(non_upper_case_globals)]
static $stat : inner_stats::$stat = inner_stats::$stat;
impl $crate::stats::StatDefinition for inner_stats::$stat {
/// The name of this statistic.
fn name(&self) -> &'static str { stringify!($stat) }
/// A human readable-description of the statistic, describing its meaning.
fn description(&self) -> &'static str { $desc }
/// The type
fn stype(&self) -> $crate::stats::StatType { $crate::stats::StatType::$stype }
/// An optional list of field names to group the statistic by.
fn group_by(&self) -> Vec<&'static str> { vec![$($tags),*] }
/// The numerical buckets and bucketing method used to group the statistic.
fn buckets(&self) -> Option<$crate::stats::Buckets> {
match self.stype() {
$crate::stats::StatType::BucketCounter => {
Some($crate::stats::Buckets::new($crate::stats::BucketMethod::$bmethod,
$blabel,
&[$($blimits as i64),* ],
))
},
_ => None
}
}
}
};
}
/// A stat definition, possibly filtered with some specific tag values.
pub struct StatDefinitionTagged {
/// The statistic definition
pub defn: &'static (dyn StatDefinition + Sync),
/// The fixed tag values. The keys *must* match keys in `defn`.
pub fixed_tags: &'static [(&'static str, &'static str)],
}
impl StatDefinitionTagged {
/// Check if the passed set of fixed tags corresponds to this statistic definition.
pub fn has_fixed_groups(&self, tags: &[(&str, &str)]) -> bool {
if self.fixed_tags.len() != tags.len() {
return false;
}
self.fixed_tags.iter().all(|self_tag| tags.contains(self_tag))
}
}
/// A trait indicating that this log can be used to trigger a statistics change.
pub trait StatTrigger {
/// The list of stats that this trigger applies to.
fn stat_list(&self) -> &[StatDefinitionTagged];
/// The condition that must be satisfied for this stat to change
fn condition(&self, _stat_id: &StatDefinitionTagged) -> bool {
false
}
/// Get the associated tag value for this log.
/// The value must be convertible to a string so it can be stored internally.
fn tag_value(&self, stat_id: &StatDefinitionTagged, _tag_name: &'static str) -> String;
/// The details of the change to make for this stat, if `condition` returned true.
fn change(&self, _stat_id: &StatDefinitionTagged) -> Option<ChangeType> {
None
}
/// The value to be used to sort the statistic into the correct bucket(s).
fn bucket_value(&self, _stat_id: &StatDefinitionTagged) -> Option<f64> {
None
}
}
/// Types of changes made to a statistic.
// LCOV_EXCL_START not interesting to track automatic derive coverage
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub enum ChangeType {
/// Increment by a fixed amount.
Incr(usize),
/// Decrement by a fixed amount.
Decr(usize),
/// Set to a specific value.
SetTo(isize),
}
/// Used to represent the upper limit of a bucket.
#[derive(Debug, Clone, Copy, serde::Serialize, PartialEq, PartialOrd, Eq, Ord)]
pub enum BucketLimit {
/// A numerical upper limit.
Num(i64),
/// Represents a bucket with no upper limit.
Unbounded,
}
impl slog::Value for BucketLimit {
fn serialize(
&self,
_record: &::slog::Record<'_>,
key: ::slog::Key,
serializer: &mut dyn (::slog::Serializer),
) -> ::slog::Result {
match *self {
BucketLimit::Num(value) => serializer.emit_i64(key, value),
BucketLimit::Unbounded => serializer.emit_str(key, "Unbounded"),
}
} // LCOV_EXCL_LINE Kcov bug?
}
impl fmt::Display for BucketLimit {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
BucketLimit::Num(val) => write!(f, "{}", val),
BucketLimit::Unbounded => write!(f, "Unbounded"),
}
}
}
/// A set of numerical buckets together with a method for sorting values into them.
#[derive(Debug, Clone, serde::Serialize, PartialEq)]
pub struct Buckets {
/// The method to use to sort values into buckets.
pub method: BucketMethod,
/// Label name describing what the buckets measure.
pub label_name: &'static str,
/// The upper bounds of the buckets.
limits: Vec<BucketLimit>,
}
impl Buckets {
/// Create a new Buckets instance.
pub fn new(method: BucketMethod, label_name: &'static str, limits: &[i64]) -> Buckets {
let mut limits: Vec<BucketLimit> = limits.iter().map(|f| BucketLimit::Num(*f)).collect();
limits.push(BucketLimit::Unbounded);
Buckets {
method,
label_name,
limits,
}
}
/// return a vector containing the indices of the buckets that should be updated
pub fn assign_buckets(&self, value: f64) -> Vec<usize> {
match self.method {
BucketMethod::CumulFreq => self
.limits
.iter()
.enumerate()
.filter(|(_, limit)| match limit {
BucketLimit::Num(b) => value <= *b as f64,
BucketLimit::Unbounded => true,
})
.map(|(i, _)| i)
.collect(),
BucketMethod::Freq => {
let mut min_limit_index = self.limits.len() - 1;
for (i, limit) in self.limits.iter().enumerate() {
if let BucketLimit::Num(b) = limit {
if value <= *b as f64 && *limit <= self.limits[min_limit_index] {
min_limit_index = i
}
}
}
vec![min_limit_index]
}
}
}
/// The number of buckets.
pub fn len(&self) -> usize {
self.limits.len()
}
/// Whether or not the number of buckets is greater than zero.
pub fn is_empty(&self) -> bool {
self.limits.is_empty()
}
/// Get the bound of an individual bucket by index.
pub fn get(&self, index: usize) -> Option<BucketLimit> {
self.limits.get(index).cloned()
}
}
/// Used to determine which buckets to update when a BucketCounter stat is updated
#[derive(Debug, Clone, Copy, serde::Serialize, PartialEq)]
pub enum BucketMethod {
/// When a value is recorded, only update the bucket it lands in
Freq,
/// When a value us recorded, update its bucket and every higher bucket
CumulFreq,
}
/// Types of statistics. Automatically determined from the `StatDefinition`.
#[derive(Debug, Clone, Copy, serde::Serialize, PartialEq)]
pub enum StatType {
/// A counter - a value that only increments.
Counter,
/// A gauge - a value that represents a current value and can go up or down.
Gauge,
/// A counter that is additionally grouped into numerical buckets
BucketCounter,
}
// LCOV_EXCL_STOP
impl slog::Value for StatType {
fn serialize(
&self,
_record: &::slog::Record<'_>,
key: ::slog::Key,
serializer: &mut dyn (::slog::Serializer),
) -> ::slog::Result {
match *self {
StatType::Counter => serializer.emit_str(key, "counter"),
StatType::Gauge => serializer.emit_str(key, "gauge"),
StatType::BucketCounter => serializer.emit_str(key, "bucket counter"),
}
} // LCOV_EXCL_LINE Kcov bug?
}
/////////////////////////////////////////////////////////////////////////////////
// The statistics tracker and related fields.
/////////////////////////////////////////////////////////////////////////////////
/// An object that tracks statistics and can be asked to log them
// LCOV_EXCL_START not interesting to track automatic derive coverage
#[derive(Debug, Default)]
pub struct StatsTracker {
// The list of statistics, mapping from stat name to value.
stats: HashMap<&'static str, Stat>,
}
// LCOV_EXCL_STOP
impl StatsTracker {
/// Create a new tracker.
pub fn new() -> Self {
Default::default()
}
/// Add a new statistic to this tracker.
pub fn add_statistic(&mut self, defn: &'static (dyn StatDefinition + Sync + RefUnwindSafe)) {
let stat = Stat {
defn,
is_grouped: !defn.group_by().is_empty(),
group_values: RwLock::new(HashMap::new()),
stat_type_data: StatTypeData::new(defn),
value: StatValue::new(0, 1),
}; // LCOV_EXCL_LINE Kcov bug?
self.stats.insert(defn.name(), stat);
} // LCOV_EXCL_LINE Kcov bug
/// Update the statistics for the current log.
///
/// This checks for any configured stats that are triggered by this log, and
/// updates their value appropriately.
fn update_stats(&self, log: &dyn StatTrigger) {
for stat_def in log.stat_list() {
if log.condition(stat_def) {
let stat = &self.stats.get(stat_def.defn.name()).unwrap_or_else(|| {
panic!(
"No statistic found with name {}, did you try writing a log through a
logger which wasn't initialized with your stats definitions?",
stat_def.defn.name()
)
});
stat.update(stat_def, log)
}
}
}
/// Log all statistics.
///
/// This function is usually just called on a timer by the logger directly.
pub fn log_all<T: StatisticsLogFormatter>(&self, logger: &StatisticsLogger) {
for stat in self.stats.values() {
// Log all the grouped and bucketed values.
let outputs = stat.get_tagged_vals();
// The `outputs` is a vector of tuples containing the (tag value, bucket_index, stat value).
for (tag_values, val) in outputs {
// The tags require a vector of (tag name, tag value) types, so get these if present.
let tags = stat.get_tag_pairs(&tag_values);
T::log_stat(
logger,
&StatLogData {
stype: stat.defn.stype(),
name: stat.defn.name(),
description: stat.defn.description(),
value: val,
tags,
},
); // LCOV_EXCL_LINE Kcov bug?
}
}
}
/// Retrieve the current values of all stats tracked by this logger.
pub fn get_stats(&self) -> Vec<StatSnapshot> {
self.stats
.values()
.map(|stat| stat.get_snapshot())
.collect::<Vec<_>>()
}
}
////////////////////////////////////
// Types to help integrate the tracker with loggers.
////////////////////////////////////
/// The default period between logging all statistics.
pub const DEFAULT_LOG_INTERVAL_SECS: u64 = 300;
/// Type alias for the return of [`define_stats`](../macro.define_stats.html).
pub type StatDefinitions = &'static [&'static (dyn StatDefinition + Sync + RefUnwindSafe)];
/// A builder to allow customization of stats config. This gives flexibility when the other
/// methods are insufficient.
///
/// Create the builder using `new()` and chain other methods as required, ending with `fuse()` to
/// return the `StatsConfig`.
///
/// # Example
/// Creating a config with a custom stats interval and the default formatter.
///
/// ```
/// # use slog_extlog::stats::*;
/// # #[tokio::main]
/// # async fn main() {
///
/// slog_extlog::define_stats! {
/// MY_STATS = {
/// SomeStat(Counter, "A test counter", []),
/// SomeOtherStat(Counter, "Another test counter", [])
/// }
/// }
///
/// let full_stats = vec![MY_STATS];
/// let logger = slog::Logger::root(slog::Discard, slog::o!());
/// let stats = StatsLoggerBuilder::default()
/// .with_stats(full_stats)
/// .fuse(logger);
///
/// # }
/// ```
#[derive(Debug, Default)]
pub struct StatsLoggerBuilder {
/// The list of statistics to track. This MUST be created using the
/// [`define_stats`](../macro.define_stats.html) macro.
pub stats: Vec<StatDefinitions>,
}
impl StatsLoggerBuilder {
/// Set the list of statistics to track.
pub fn with_stats(mut self, stats: Vec<StatDefinitions>) -> Self {
self.stats = stats;
self
}
/// Construct the StatisticsLogger
pub fn fuse(self, logger: slog::Logger) -> StatisticsLogger {
let mut tracker = StatsTracker::new();
for set in self.stats {
for s in set {
tracker.add_statistic(*s)
}
}
StatisticsLogger {
logger,
tracker: Arc::new(tracker),
}
}
/// Construct the StatisticsLogger - this will start the interval logging if requested.
///
/// interval_secs: The period, in seconds, to log the generated metrics into the log stream.
/// One log will be generated for each metric value.
#[cfg(feature = "interval_logging")]
pub fn fuse_with_log_interval<T: StatisticsLogFormatter>(
self,
interval_secs: u64,
logger: slog::Logger,
) -> StatisticsLogger {
// Fuse the logger using the standard function
let stats_logger = self.fuse(logger);
// Clone the logger for using on the timer.
let timer_full_logger = stats_logger.clone();
tokio::spawn(async move {
let mut interval = tokio::time::interval(Duration::from_secs(interval_secs));
// The first tick completes immediately, so we skip it.
interval.tick().await;
loop {
interval.tick().await;
timer_full_logger.tracker.log_all::<T>(&timer_full_logger);
}
});
// Return the fused logger.
stats_logger
}
}
/// Data and callback type for actually generating the log.
///
/// This allows the user to decide what format to actually log the stats in.
// LCOV_EXCL_START not interesting to track automatic derive coverage
#[derive(Debug)]
pub struct StatLogData<'a> {
/// The description, as provided on the definition.
pub description: &'static str,
/// The statistic type, automatically determined from the definition.
pub stype: StatType,
/// The statistic name, as provided on the definition.
pub name: &'static str,
/// The current value.
pub value: f64,
/// The groups and name.
pub tags: Vec<(&'static str, &'a str)>,
}
/// Structure to use for the default implementation of `StatisticsLogFormatter`.
#[derive(Debug, Clone)]
pub struct DefaultStatisticsLogFormatter;
// LCOV_EXCL_STOP
/// The log identifier for the default formatter.
pub static DEFAULT_LOG_ID: &str = "STATS-1";
impl StatisticsLogFormatter for DefaultStatisticsLogFormatter {
/// The formatting callback. This default implementation just logs each field.
fn log_stat(logger: &StatisticsLogger, stat: &StatLogData<'_>)
where
Self: Sized,
{
// A realistic implementation would use `xlog`. However, since the derivation of
// `ExtLoggable` depends on this crate, we can't use it here!
//
// So just log the value manually using the `slog` macros.
info!(logger, "New statistic value";
"log_id" => DEFAULT_LOG_ID,
"name" => stat.name,
"metric_type" => stat.stype,
"description" => stat.description,
"value" => stat.value,
"tags" => stat.tags.iter().
map(|x| format!("{}={}", x.0, x.1)).collect::<Vec<_>>().join(","))
}
}
/// A trait object to allow users to customise the format of stats when logged.
pub trait StatisticsLogFormatter: Sync + Send + 'static {
/// The formatting callback. This should take the statistic information and log it through the
/// provided logger in the relevant format.
///
/// The `DefaultStatisticsLogFormatter` provides a basic format, or users can override the
/// format of the generated logs by providing an object that implements this trait in the
/// `StatsConfig`.
fn log_stat(logger: &StatisticsLogger, stat: &StatLogData<'_>)
where
Self: Sized;
}
/// A logger with statistics tracking.
///
/// This should only be created through the `new` method.
#[derive(Debug, Clone)]
pub struct StatisticsLogger {
/// The logger that receives the logs.
logger: slog::Logger,
/// The stats tracker.
tracker: Arc<StatsTracker>,
}
impl Deref for StatisticsLogger {
type Target = slog::Logger;
fn deref(&self) -> &Self::Target {
&self.logger
}
}
impl StatisticsLogger {
/// Build a child logger with new parameters.
///
/// This is essentially a wrapper around `slog::Logger::new()`.
pub fn with_params<P>(&self, params: slog::OwnedKV<P>) -> Self
where
P: slog::SendSyncRefUnwindSafeKV + 'static,
{
StatisticsLogger {
logger: self.logger.new(params),
tracker: self.tracker.clone(),
} // LCOV_EXCL_LINE Kcov bug
}
/// Update the statistics for the current log.
pub fn update_stats(&self, log: &dyn StatTrigger) {
self.tracker.update_stats(log)
}
/// Modify the logger field without changing the stats tracker
pub fn set_slog_logger(&mut self, logger: slog::Logger) {
self.logger = logger;
}
/// Retrieve the current values of all stats tracked by this logger.
pub fn get_stats(&self) -> Vec<StatSnapshot> {
self.tracker.get_stats()
}
}
/// The values contained in a `StatSnapshot` for each stat type.
#[derive(Debug)]
pub enum StatSnapshotValues {
/// `StatSnapshot` values for the Counter stat type.
Counter(Vec<StatSnapshotValue>),
/// `StatSnapshot` values for the Gauge stat type.
Gauge(Vec<StatSnapshotValue>),
/// Bucket description, and `StatSnapshot` values by bucket for the BucketCounter stat type.
BucketCounter(Buckets, Vec<(StatSnapshotValue, BucketLimit)>),
}
impl StatSnapshotValues {
/// Returns true if self contains no StatSnapshotValue entries.
pub fn is_empty(&self) -> bool {
match self {
StatSnapshotValues::Counter(ref vals) | StatSnapshotValues::Gauge(ref vals) => {
vals.is_empty()
}
StatSnapshotValues::BucketCounter(_, ref vals) => vals.is_empty(),
}
}
}
/// A snapshot of the current values for a particular stat.
// LCOV_EXCL_START not interesting to track automatic derive coverage
#[derive(Debug)]
pub struct StatSnapshot {
/// A configured statistic, defined in terms of the external logs that trigger it to change.
pub definition: &'static dyn StatDefinition,
/// The values contained in a `StatSnapshot` for each stat type.
pub values: StatSnapshotValues,
}
// LCOV_EXCL_STOP
impl StatSnapshot {
/// Create a new snapshot of a stat. The StatSnapshotValues enum variant passed
/// should match the stat type in the definition.
pub fn new(definition: &'static dyn StatDefinition, values: StatSnapshotValues) -> Self {
StatSnapshot { definition, values }
}
}
/// A snapshot of a current (possibly grouped) value for a stat.
// LCOV_EXCL_START not interesting to track automatic derive coverage
#[derive(Debug)]
pub struct StatSnapshotValue {
/// A vec of the set of tags that this value belongs to. A group can have several tags
/// and the stat is counted separately for all distinct combinations of tag values.
/// This may be an empty vec is the stat is not grouped.
pub group_values: Vec<String>,
/// The value of the stat with the above combination of groups (note that this may be bucketed).
pub value: f64,
}
// LCOV_EXCL_STOP
impl StatSnapshotValue {
/// Create a new snapshot value.
pub fn new(group_values: Vec<String>, value: f64) -> Self {
StatSnapshotValue {
group_values,
value,
}
}
}
///////////////////////////
// Private types and private methods.
///////////////////////////
/// A struct used to store any data internal to a stat that is specific to the
/// stat type.
#[derive(Debug)]
enum StatTypeData {
Counter,
Gauge,
BucketCounter(BucketCounterData),
}
impl StatTypeData {
/// Create a new `StatTypeData`
fn new(defn: &'static dyn StatDefinition) -> Self {
match defn.stype() {
StatType::Counter => StatTypeData::Counter,
StatType::Gauge => StatTypeData::Gauge,
StatType::BucketCounter => {
let is_grouped = !defn.group_by().is_empty();
StatTypeData::BucketCounter(BucketCounterData::new(
defn.buckets().expect(
"Stat definition with type BucketCounter did not contain bucket info",
),
is_grouped,
))
}
}
}
/// Update the stat values
fn update(&self, defn: &StatDefinitionTagged, trigger: &dyn StatTrigger) {
if let StatTypeData::BucketCounter(ref bucket_counter_data) = self {
bucket_counter_data.update(defn, trigger);
}
}
/// Get all the tags for this stat as a vector of `(name, value)` tuples.
fn get_tag_pairs<'a>(
&self,
tag_values: &'a str,
defn: &dyn StatDefinition,
) -> Option<Vec<(&'static str, &'a str)>> {
if let StatTypeData::BucketCounter(ref bucket_counter_data) = self {
Some(bucket_counter_data.get_tag_pairs(tag_values, defn))
} else {
None
}
}
/// Get all the tagged value names currently tracked.
fn get_tagged_vals(&self) -> Option<Vec<(String, f64)>> {
if let StatTypeData::BucketCounter(ref bucket_counter_data) = self {
Some(bucket_counter_data.get_tagged_vals())
} else {
None
}
}
}
/// Contains data that is specific to the `BucketCounter` stat type.
#[derive(Debug)]
struct BucketCounterData {
buckets: Buckets,
bucket_values: Vec<StatValue>,
bucket_group_values: RwLock<HashMap<String, Vec<StatValue>>>,
is_grouped: bool,
}
impl BucketCounterData {
fn new(buckets: Buckets, is_grouped: bool) -> Self {
let buckets_len = buckets.len();
let mut bucket_values = Vec::new();
bucket_values.reserve_exact(buckets_len);
for _ in 0..buckets_len {
bucket_values.push(StatValue::new(0, 1));
}
BucketCounterData {
buckets,
bucket_values,
bucket_group_values: RwLock::new(HashMap::new()),
is_grouped,
}
}
/// Update the stat values.
fn update(&self, defn: &StatDefinitionTagged, trigger: &dyn StatTrigger) {
// Update the bucketed values.
let bucket_value = trigger.bucket_value(defn).expect("Bad log definition");
let buckets_to_update = self.buckets.assign_buckets(bucket_value);
for index in &buckets_to_update {
self.bucket_values
.get(*index)
.expect("Invalid bucket index")
.update(&trigger.change(defn).expect("Bad log definition"));
}
if self.is_grouped {
// Update the grouped and bucketed values.
self.update_grouped(defn, trigger, &buckets_to_update);
}
}
/// Update the grouped stat values.
fn update_grouped(
&self,
defn: &StatDefinitionTagged,
trigger: &dyn StatTrigger,
buckets_to_update: &[usize],
) {
let change = trigger.change(defn).expect("Bad log definition");
let tag_values = defn
.defn
.group_by()
.iter()
.map(|n| trigger.tag_value(defn, n))
.collect::<Vec<String>>()
.join(","); // LCOV_EXCL_LINE Kcov bug?
let found_values = {
let inner_vals = self.bucket_group_values.read().expect("Poisoned lock");
if let Some(tagged_bucket_vals) = inner_vals.get(&tag_values) {
update_bucket_values(tagged_bucket_vals, buckets_to_update, &change);
true
} else {
false
}
};
if !found_values {
// we didn't find bucketed values for this tag combination. Create them now.
let mut new_bucket_vals = Vec::new();
let bucket_len = self.buckets.len();
new_bucket_vals.reserve_exact(bucket_len);
for _ in 0..bucket_len {
new_bucket_vals.push(StatValue::new(0, 1));
}
let mut inner_vals = self.bucket_group_values.write().expect("Poisoned lock");
// It's possible that while we were waiting for the write lock another thread got
// in and created the bucketed entries, so check again.
let vals = inner_vals
.entry(tag_values)
.or_insert_with(|| new_bucket_vals);
update_bucket_values(vals, buckets_to_update, &change);
}
}
/// Get all the tags for this stat as a vector of `(name, value)` tuples.
fn get_tag_pairs<'a>(
&self,
tag_values: &'a str,
defn: &dyn StatDefinition,
) -> Vec<(&'static str, &'a str)> {
let mut tag_names = defn.group_by();
// Add the bucket label name as an additional tag name.
tag_names.push(self.buckets.label_name);
tag_names
.iter()
.cloned()
.zip(tag_values.split(','))
.collect::<Vec<_>>()
}
/// Get all the tagged values currently tracked.
fn get_tagged_vals(&self) -> Vec<(String, f64)> {
if self.is_grouped {
let mut tag_bucket_vals = Vec::new();
{
// Only hold the read lock long enough to get the keys, bucket indices, and values.
let inner_vals = self.bucket_group_values.read().expect("Poisoned lock");
for (group_values_str, bucket_values) in inner_vals.iter() {
for (index, val) in bucket_values.iter().enumerate() {
tag_bucket_vals.push((group_values_str.to_string(), index, val.as_float()));
}
}
}
tag_bucket_vals
.into_iter()
.map(|(mut tag_values, index, val)| {
let bucket = self.buckets.get(index).expect("Invalid bucket index");
// Add the bucket label value as an additional tag value.
tag_values.push_str(&format!(",{}", bucket));
(tag_values, val)
})
.collect()
} else {
self.bucket_values
.iter()
.enumerate()
.map(|(index, val)| {
let bucket = self.buckets.get(index).expect("Invalid bucket index");
(bucket.to_string(), val.as_float())
})
.collect()
}
}
/// Get a snapshot of the current stat values.
fn get_snapshot_values(&self) -> Vec<(StatSnapshotValue, BucketLimit)> {
if self.is_grouped {
let mut tag_bucket_vals = Vec::new();
{
// Only hold the read lock long enough to get the keys, bucket indices, and values.
let inner_vals = self.bucket_group_values.read().expect("Poisoned lock");
for (group_values_str, bucket_values) in inner_vals.iter() {
for (index, val) in bucket_values.iter().enumerate() {
tag_bucket_vals.push((group_values_str.to_string(), index, val.as_float()));
}
}
}
tag_bucket_vals
.into_iter()
.map(|(tag_values, index, val)| {
let bucket = self.buckets.get(index).expect("Invalid bucket index");
let group_values = tag_values
.split(',')
.map(|group| group.to_string())
.collect::<Vec<_>>();
(StatSnapshotValue::new(group_values, val), bucket)
})
.collect()
} else {
self.bucket_values
.iter()
.enumerate()
.map(|(index, val)| {
let bucket = self.buckets.get(index).expect("Invalid bucket index");
(StatSnapshotValue::new(vec![], val.as_float()), bucket)
})
.collect()
}
}
}
// LCOV_EXCL_START not interesting to track automatic derive coverage
/// The internal representation of a tracked statistic.
#[derive(Debug)]
struct Stat {
// The definition fields, as a trait object.
defn: &'static (dyn StatDefinition + Sync + RefUnwindSafe),
// The value - if grouped, this is the total value across all statistics.
value: StatValue,
// Does this stat use groups. Cached here for efficiency.
is_grouped: bool,
// The fields the stat is grouped by. If empty, then there is no grouping.
group_values: RwLock<HashMap<String, StatValue>>,
// Data specific to the stat type.
stat_type_data: StatTypeData,
}
// LCOV_EXCL_STOP
impl Stat {
// Get all the tags for this stat as a vector of `(name, value)` tuples.
fn get_tag_pairs<'a>(&self, tag_values: &'a str) -> Vec<(&'static str, &'a str)> {
// if the stat type has its own `get_tag_pairs` method use that, otherwise
// use the default.
self.stat_type_data
.get_tag_pairs(tag_values, self.defn)
.unwrap_or_else(|| {
self.defn
.group_by()
.iter()
.cloned()
.zip(tag_values.split(','))
.collect::<Vec<_>>()
})
}
/// Get all the tagged value names currently tracked.
fn get_tagged_vals(&self) -> Vec<(String, f64)> {
// if the stat type has its own `get_tagged_vals` method use that, otherwise
// use the default.
self.stat_type_data.get_tagged_vals().unwrap_or_else(|| {
if self.is_grouped {
// Only hold the read lock long enough to get the keys and values.
let inner_vals = self.group_values.read().expect("Poisoned lock");
inner_vals
.iter()
.map(|(group_values_str, value)| {
(group_values_str.to_string(), value.as_float())
})
.collect()
} else {
vec![("".to_string(), self.value.as_float())]
}
})
}
/// Update the stat's value(s) according to the given `StatTrigger` and `StatDefinition`.
fn update(&self, defn: &StatDefinitionTagged, trigger: &dyn StatTrigger) {
// update the stat value
self.value
.update(&trigger.change(defn).expect("Bad log definition"));
// If the stat is grouped, update the grouped values.
if self.is_grouped {
self.update_grouped(defn, trigger)
}
// Update type-specific stat data.
self.stat_type_data.update(defn, trigger);
}
fn update_grouped(&self, defn: &StatDefinitionTagged, trigger: &dyn StatTrigger) {
let change = trigger.change(defn).expect("Bad log definition");
let tag_values = self
.defn
.group_by()
.iter()
.map(|n| trigger.tag_value(defn, n))
.collect::<Vec<String>>()
.join(","); // LCOV_EXCL_LINE Kcov bug?
let found_values = {
let inner_vals = self.group_values.read().expect("Poisoned lock");
if let Some(val) = inner_vals.get(&tag_values) {
val.update(&change);
true
} else {
false
}
};
if !found_values {
// We didn't find a grouped value. Get the write lock on the map so we can add it.
let mut inner_vals = self.group_values.write().expect("Poisoned lock");
// It's possible that while we were waiting for the write lock another thread got
// in and created the stat entry, so check again.
let val = inner_vals
.entry(tag_values)
.or_insert_with(|| StatValue::new(0, 1));
val.update(&change);
}
}
/// Get the current values for this stat as a StatSnapshot.
fn get_snapshot(&self) -> StatSnapshot {
let stat_snapshot_values = match self.stat_type_data {
StatTypeData::BucketCounter(ref bucket_counter_data) => {
StatSnapshotValues::BucketCounter(
bucket_counter_data.buckets.clone(),
bucket_counter_data.get_snapshot_values(),
)
}
StatTypeData::Counter => StatSnapshotValues::Counter(self.get_snapshot_values()),
StatTypeData::Gauge => StatSnapshotValues::Gauge(self.get_snapshot_values()),
};
StatSnapshot::new(self.defn, stat_snapshot_values)
}
/// Get a snapshot of the current stat values.
fn get_snapshot_values(&self) -> Vec<StatSnapshotValue> {
self.get_tagged_vals()
.iter()
.map(|(group_values_str, value)| {
let group_values = if !group_values_str.is_empty() {
group_values_str
.split(',')
.map(|group| group.to_string())
.collect::<Vec<_>>()
} else {
vec![]
};
StatSnapshotValue::new(group_values, *value)
})
.collect()
}
}
// LCOV_EXCL_START not interesting to track automatic derive coverage
/// A single statistic value.
#[derive(Debug)]
struct StatValue {
// The tracked integer value.
num: AtomicIsize,
// A divisor for printing the stat value only - currently this is always 1 but is here
// to allow in future for, say, percentages.
divisor: u64,
}
// LCOV_EXCL_STOP
impl StatValue {
/// Create a new value.
fn new(num: isize, divisor: u64) -> Self {
StatValue {
num: AtomicIsize::new(num),
divisor,
}
}
/// Update the stat and return whether it has changed.
fn update(&self, change: &ChangeType) -> bool {
match *change {
ChangeType::Incr(i) => {
self.num.fetch_add(i as isize, Ordering::Relaxed);
true
}
ChangeType::Decr(d) => {
self.num.fetch_sub(d as isize, Ordering::Relaxed);
true
}
ChangeType::SetTo(v) => self.num.swap(v, Ordering::Relaxed) != v,
}
}
/// Return the statistic value as a float, for use in display.
fn as_float(&self) -> f64 {
(self.num.load(Ordering::Relaxed) as f64) / (self.divisor as isize as f64)
}
}
fn update_bucket_values(
bucket_values: &[StatValue],
buckets_to_update: &[usize],
change: &ChangeType,
) {
for index in buckets_to_update.iter() {
bucket_values
.get(*index)
.expect("Invalid bucket index")
.update(change);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[allow(dead_code)]
struct DummyNonCloneFormatter;
impl StatisticsLogFormatter for DummyNonCloneFormatter {
fn log_stat(_logger: &StatisticsLogger, _stat: &StatLogData<'_>)
where
Self: Sized,
{
}
}
#[test]
// Check that loggers can be cloned even if the formatter can't.
fn check_clone() {
let builder = StatsLoggerBuilder::default();
let logger = builder.fuse(slog::Logger::root(slog::Discard, slog::o!()));
fn is_clone<T: Clone>(_: &T) {}
is_clone(&logger);
}
}