105 lines
2.3 KiB
Go
105 lines
2.3 KiB
Go
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package metrics
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import (
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"fmt"
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"io"
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"sync/atomic"
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)
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// NewCounter registers and returns new counter with the given name.
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//
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// name must be valid Prometheus-compatible metric with possible lables.
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// For instance,
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//
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// * foo
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// * foo{bar="baz"}
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// * foo{bar="baz",aaa="b"}
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//
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// The returned counter is safe to use from concurrent goroutines.
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func NewCounter(name string) *Counter {
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c := &Counter{}
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registerMetric(name, c)
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return c
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}
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// Counter is a counter.
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//
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// It may be used as a gauge if Dec and Set are called.
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type Counter struct {
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n uint64
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}
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// Inc increments c.
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func (c *Counter) Inc() {
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atomic.AddUint64(&c.n, 1)
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}
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// Dec decrements c.
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func (c *Counter) Dec() {
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atomic.AddUint64(&c.n, ^uint64(0))
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}
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// Add adds n to c.
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func (c *Counter) Add(n int) {
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atomic.AddUint64(&c.n, uint64(n))
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}
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// Get returns the current value for c.
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func (c *Counter) Get() uint64 {
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return atomic.LoadUint64(&c.n)
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}
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// Set sets c value to n.
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func (c *Counter) Set(n uint64) {
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atomic.StoreUint64(&c.n, n)
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}
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// marshalTo marshals c with the given prefix to w.
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func (c *Counter) marshalTo(prefix string, w io.Writer) {
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v := c.Get()
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fmt.Fprintf(w, "%s %d\n", prefix, v)
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}
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// GetOrCreateCounter returns registered counter with the given name
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// or creates new counter if the registry doesn't contain counter with
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// the given name.
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//
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// name must be valid Prometheus-compatible metric with possible lables.
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// For instance,
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//
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// * foo
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// * foo{bar="baz"}
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// * foo{bar="baz",aaa="b"}
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//
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// The returned counter is safe to use from concurrent goroutines.
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//
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// Performance tip: prefer NewCounter instead of GetOrCreateCounter.
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func GetOrCreateCounter(name string) *Counter {
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metricsMapLock.Lock()
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nm := metricsMap[name]
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metricsMapLock.Unlock()
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if nm == nil {
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// Slow path - create and register missing counter.
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if err := validateMetric(name); err != nil {
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panic(fmt.Errorf("BUG: invalid metric name %q: %s", name, err))
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}
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nmNew := &namedMetric{
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name: name,
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metric: &Counter{},
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}
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metricsMapLock.Lock()
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nm = metricsMap[name]
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if nm == nil {
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nm = nmNew
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metricsMap[name] = nm
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metricsList = append(metricsList, nm)
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}
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metricsMapLock.Unlock()
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}
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c, ok := nm.metric.(*Counter)
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if !ok {
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panic(fmt.Errorf("BUG: metric %q isn't a Counter. It is %T", name, nm.metric))
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}
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return c
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}
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