Documentation
¶
Overview ¶
Package metric implements an abstraction for safely managing metrics in concurrent environments.
Index ¶
- Constants
- func DecreasePendingEvents(tablePrefix string, workspace string, destType string, value float64)
- func IncreasePendingEvents(tablePrefix string, workspace string, destType string, value float64)
- type Counter
- type Gauge
- type Manager
- type Measurement
- type MovingAverage
- type Registry
- type SimpleEWMA
- type Tags
- type TagsWithValue
- type VariableEWMA
Constants ¶
const ( // By default, we average over a one-minute period, which means the average // age of the metrics in the period is 30 seconds. AVG_METRIC_AGE float64 = 30.0 // The formula for computing the decay factor from the average age comes // from "Production and Operations Analysis" by Steven Nahmias. DECAY float64 = 2 / (float64(AVG_METRIC_AGE) + 1) // For best results, the moving average should not be initialized to the // samples it sees immediately. The book "Production and Operations // Analysis" by Steven Nahmias suggests initializing the moving average to // the mean of the first 10 samples. Until the VariableEwma has seen this // many samples, it is not "ready" to be queried for the value of the // moving average. This adds some memory cost. WARMUP_SAMPLES uint8 = 10 )
const ALL = "ALL"
const JOBSDB_PENDING_EVENTS_COUNT = "jobsdb_%s_pending_events_count"
const (
PUBLISHED_METRICS string = "published_metrics"
)
Variables ¶
This section is empty.
Functions ¶
func DecreasePendingEvents ¶
DecreasePendingEvents increments three gauges, the dest & workspace-specific gauge, plus two aggregate (global) gauges
Types ¶
type Counter ¶
type Counter interface {
// Inc increments the counter by 1. Use Add to increment it by arbitrary
// non-negative values.
Inc()
// Add adds the given value to the counter. It panics if the value is <
// 0.
Add(float64)
// Value gets the current value of the counter.
Value() float64
}
Counter counts monotonically increasing values
type Gauge ¶
type Gauge interface {
// Set sets the given value to the gauge.
Set(float64)
// Inc increments the gauge by 1. Use Add to increment it by arbitrary
// values.
Inc()
// Dec decrements the gauge by 1. Use Sub to decrement it by arbitrary
// values.
Dec()
// Add adds the given value to the counter.
Add(val float64)
// Sub substracts the given value from the counter.
Sub(float64)
// SetToCurrentTime sets the current UNIX time as the gauge's value
SetToCurrentTime()
// Value gets the current value of the counter.
Value() float64
// IntValue gets the current value of the counter as an int.
IntValue() int
// ValueAsTime gets the current value of the counter as time.
ValueAsTime() time.Time
}
Gauge keeps track of increasing/decreasing or generally arbitrary values. You can even use a gauge to keep track of time, e.g. when was the last time an event happened!
type Manager ¶
type Manager interface {
// GetRegistry gets a registry by its key
GetRegistry(key string) Registry
// Reset cleans all registries
Reset()
}
Manager is the entry-point for retrieving metric registries
type Measurement ¶
type Measurement interface {
// GetName gets the name of the measurement
GetName() string
// GetTags gets the tags of the measurement
GetTags() map[string]string
}
Measurement acts as a key in a Registry.
type MovingAverage ¶
MovingAverage is the interface that computes a moving average over a time- series stream of numbers. The average may be over a window or exponentially decaying.
func NewMovingAverage ¶
func NewMovingAverage(age ...float64) MovingAverage
NewMovingAverage constructs a MovingAverage that computes an average with the desired characteristics in the moving window or exponential decay. If no age is given, it constructs a default exponentially weighted implementation that consumes minimal memory. The age is related to the decay factor alpha by the formula given for the DECAY constant. It signifies the average age of the samples as time goes to infinity.
type Registry ¶
type Registry interface {
// GetCounter gets a counter by key. If a value for this key
// already exists but corresponds to another measurement type,
// e.g. a Gauge, an error is returned
GetCounter(Measurement) (Counter, error)
// MustGetCounter gets a counter by key. If a value for this key
// already exists but corresponds to another measurement type,
// e.g. a Gauge, it panics
MustGetCounter(Measurement) Counter
// GetGauge gets a gauge by key. If a value for this key
// already exists but corresponds to another measurement
// type, e.g. a Counter, an error is returned
GetGauge(Measurement) (Gauge, error)
// MustGetGauge gets a gauge by key. If a value for this key
// already exists but corresponds to another measurement type,
// e.g. a Counter, it panics
MustGetGauge(Measurement) Gauge
// GetMovingAverage gets a moving average by key. If a value for this key
// already exists but corresponds to another measurement
// type, e.g. a Counter, an error is returned
GetSimpleMovingAvg(Measurement) (MovingAverage, error)
// MustGetMovingAverage gets a moving average by key. If a value for this key
// already exists but corresponds to another measurement type,
// e.g. a Counter, it panics
MustGetSimpleMovingAvg(Measurement) MovingAverage
// GetMovingAverage gets a moving average by key. If a value for this key
// already exists but corresponds to another measurement
// type, e.g. a Counter, an error is returned
GetVarMovingAvg(m Measurement, age float64) (MovingAverage, error)
// MustGetMovingAverage gets a moving average by key. If a value for this key
// already exists but corresponds to another measurement type,
// e.g. a Counter, it panics
MustGetVarMovingAvg(m Measurement, age float64) MovingAverage
// Range scans across all metrics
Range(f func(key, value interface{}) bool)
// GetMetricsByName gets all metrics with this name
GetMetricsByName(name string) []TagsWithValue
}
Registry is a safe way to capture metrics in a highly concurrent environment. The registry is responsible for creating and storing the various measurements and guarantees consistency when competing goroutines try to update the same measurement at the same time.
E.g. assuming that you already have created a new registry
registry := NewRegistry()
the following is guaranteed to be executed atomically:
registry.MustGetCounter("key").Inc()
func NewRegistry ¶
func NewRegistry() Registry
type SimpleEWMA ¶
type SimpleEWMA struct {
// contains filtered or unexported fields
}
A SimpleEWMA represents the exponentially weighted moving average of a series of numbers. It WILL have different behavior than the VariableEWMA for multiple reasons. It has no warm-up period and it uses a constant decay. These properties let it use less memory. It will also behave differently when it's equal to zero, which is assumed to mean uninitialized, so if a value is likely to actually become zero over time, then any non-zero value will cause a sharp jump instead of a small change. However, note that this takes a long time, and the value may just decays to a stable value that's close to zero, but which won't be mistaken for uninitialized. See http://play.golang.org/p/litxBDr_RC for example.
func (*SimpleEWMA) Add ¶
func (e *SimpleEWMA) Add(value float64)
Add adds a value to the series and updates the moving average.
func (*SimpleEWMA) Value ¶
func (e *SimpleEWMA) Value() float64
Value returns the current value of the moving average.
type TagsWithValue ¶
type TagsWithValue struct {
Tags Tags
Value interface{}
}
type VariableEWMA ¶
type VariableEWMA struct {
// contains filtered or unexported fields
}
VariableEWMA represents the exponentially weighted moving average of a series of numbers. Unlike SimpleEWMA, it supports a custom age, and thus uses more memory.
func (*VariableEWMA) Add ¶
func (e *VariableEWMA) Add(value float64)
Add adds a value to the series and updates the moving average.
func (*VariableEWMA) Value ¶
func (e *VariableEWMA) Value() float64
Value returns the current value of the average, or 0.0 if the series hasn't warmed up yet.
Source Files