168 lines
4.6 KiB
Go
168 lines
4.6 KiB
Go
package metrics
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import (
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"fmt"
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"reflect"
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"sync"
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)
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// DuplicateMetric is the error returned by Registry.Register when a metric
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// already exists. If you mean to Register that metric you must first
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// Unregister the existing metric.
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type DuplicateMetric string
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func (err DuplicateMetric) Error() string {
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return fmt.Sprintf("duplicate metric: %s", string(err))
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}
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// A Registry holds references to a set of metrics by name and can iterate
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// over them, calling callback functions provided by the user.
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//
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// This is an interface so as to encourage other structs to implement
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// the Registry API as appropriate.
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type Registry interface {
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// Call the given function for each registered metric.
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Each(func(string, interface{}))
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// Get the metric by the given name or nil if none is registered.
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Get(string) interface{}
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// Gets an existing metric or registers the given one.
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// The interface can be the metric to register if not found in registry,
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// or a function returning the metric for lazy instantiation.
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GetOrRegister(string, interface{}) interface{}
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// Register the given metric under the given name.
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Register(string, interface{}) error
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// Run all registered healthchecks.
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RunHealthchecks()
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// Unregister the metric with the given name.
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Unregister(string)
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}
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// The standard implementation of a Registry is a mutex-protected map
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// of names to metrics.
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type StandardRegistry struct {
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metrics map[string]interface{}
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mutex sync.Mutex
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}
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// Create a new registry.
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func NewRegistry() Registry {
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return &StandardRegistry{metrics: make(map[string]interface{})}
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}
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// Call the given function for each registered metric.
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func (r *StandardRegistry) Each(f func(string, interface{})) {
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for name, i := range r.registered() {
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f(name, i)
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}
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}
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// Get the metric by the given name or nil if none is registered.
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func (r *StandardRegistry) Get(name string) interface{} {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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return r.metrics[name]
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}
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// Gets an existing metric or creates and registers a new one. Threadsafe
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// alternative to calling Get and Register on failure.
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// The interface can be the metric to register if not found in registry,
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// or a function returning the metric for lazy instantiation.
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func (r *StandardRegistry) GetOrRegister(name string, i interface{}) interface{} {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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if metric, ok := r.metrics[name]; ok {
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return metric
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}
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if v := reflect.ValueOf(i); v.Kind() == reflect.Func {
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i = v.Call(nil)[0].Interface()
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}
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r.register(name, i)
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return i
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}
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// Register the given metric under the given name. Returns a DuplicateMetric
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// if a metric by the given name is already registered.
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func (r *StandardRegistry) Register(name string, i interface{}) error {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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return r.register(name, i)
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}
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// Run all registered healthchecks.
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func (r *StandardRegistry) RunHealthchecks() {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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for _, i := range r.metrics {
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if h, ok := i.(Healthcheck); ok {
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h.Check()
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}
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}
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}
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// Unregister the metric with the given name.
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func (r *StandardRegistry) Unregister(name string) {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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delete(r.metrics, name)
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}
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func (r *StandardRegistry) register(name string, i interface{}) error {
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if _, ok := r.metrics[name]; ok {
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return DuplicateMetric(name)
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}
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switch i.(type) {
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case Counter, Gauge, GaugeFloat64, Healthcheck, Histogram, Meter, Timer:
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r.metrics[name] = i
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}
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return nil
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}
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func (r *StandardRegistry) registered() map[string]interface{} {
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metrics := make(map[string]interface{}, len(r.metrics))
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r.mutex.Lock()
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defer r.mutex.Unlock()
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for name, i := range r.metrics {
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metrics[name] = i
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}
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return metrics
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}
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var DefaultRegistry Registry = NewRegistry()
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// Call the given function for each registered metric.
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func Each(f func(string, interface{})) {
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DefaultRegistry.Each(f)
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}
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// Get the metric by the given name or nil if none is registered.
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func Get(name string) interface{} {
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return DefaultRegistry.Get(name)
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}
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// Gets an existing metric or creates and registers a new one. Threadsafe
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// alternative to calling Get and Register on failure.
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func GetOrRegister(name string, i interface{}) interface{} {
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return DefaultRegistry.GetOrRegister(name, i)
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}
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// Register the given metric under the given name. Returns a DuplicateMetric
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// if a metric by the given name is already registered.
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func Register(name string, i interface{}) error {
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return DefaultRegistry.Register(name, i)
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}
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// Run all registered healthchecks.
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func RunHealthchecks() {
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DefaultRegistry.RunHealthchecks()
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}
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// Unregister the metric with the given name.
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func Unregister(name string) {
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DefaultRegistry.Unregister(name)
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}
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