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// Package stats defines a lightweight interface for collecting statistics. It
// doesn't provide an implementation, just the shared interface.
package stats
// Client provides methods to collection statistics.
type Client interface {
// BumpAvg bumps the average for the given key.
BumpAvg(key string, val float64)
// BumpSum bumps the sum for the given key.
BumpSum(key string, val float64)
// BumpHistogram bumps the histogram for the given key.
BumpHistogram(key string, val float64)
// BumpTime is a special version of BumpHistogram which is specialized for
// timers. Calling it starts the timer, and it returns a value on which End()
// can be called to indicate finishing the timer. A convenient way of
// recording the duration of a function is calling it like such at the top of
// the function:
//
// defer s.BumpTime("my.function").End()
BumpTime(key string) interface {
End()
}
}
// PrefixClient adds multiple keys for the same value, with each prefix
// added to the key and calls the underlying client.
func PrefixClient(prefixes []string, client Client) Client {
return &prefixClient{
Prefixes: prefixes,
Client: client,
}
}
type prefixClient struct {
Prefixes []string
Client Client
}
func (p *prefixClient) BumpAvg(key string, val float64) {
for _, prefix := range p.Prefixes {
p.Client.BumpAvg(prefix+key, val)
}
}
func (p *prefixClient) BumpSum(key string, val float64) {
for _, prefix := range p.Prefixes {
p.Client.BumpSum(prefix+key, val)
}
}
func (p *prefixClient) BumpHistogram(key string, val float64) {
for _, prefix := range p.Prefixes {
p.Client.BumpHistogram(prefix+key, val)
}
}
func (p *prefixClient) BumpTime(key string) interface {
End()
} {
var m multiEnder
for _, prefix := range p.Prefixes {
m = append(m, p.Client.BumpTime(prefix+key))
}
return m
}
// multiEnder combines many enders together.
type multiEnder []interface {
End()
}
func (m multiEnder) End() {
for _, e := range m {
e.End()
}
}
// HookClient is useful for testing. It provides optional hooks for each
// expected method in the interface, which if provided will be called. If a
// hook is not provided, it will be ignored.
type HookClient struct {
BumpAvgHook func(key string, val float64)
BumpSumHook func(key string, val float64)
BumpHistogramHook func(key string, val float64)
BumpTimeHook func(key string) interface {
End()
}
}
// BumpAvg will call BumpAvgHook if defined.
func (c *HookClient) BumpAvg(key string, val float64) {
if c.BumpAvgHook != nil {
c.BumpAvgHook(key, val)
}
}
// BumpSum will call BumpSumHook if defined.
func (c *HookClient) BumpSum(key string, val float64) {
if c.BumpSumHook != nil {
c.BumpSumHook(key, val)
}
}
// BumpHistogram will call BumpHistogramHook if defined.
func (c *HookClient) BumpHistogram(key string, val float64) {
if c.BumpHistogramHook != nil {
c.BumpHistogramHook(key, val)
}
}
// BumpTime will call BumpTimeHook if defined.
func (c *HookClient) BumpTime(key string) interface {
End()
} {
if c.BumpTimeHook != nil {
return c.BumpTimeHook(key)
}
return NoOpEnd
}
type noOpEnd struct{}
func (n noOpEnd) End() {}
// NoOpEnd provides a dummy value for use in tests as valid return value for
// BumpTime().
var NoOpEnd = noOpEnd{}
// BumpAvg calls BumpAvg on the Client if it isn't nil. This is useful when a
// component has an optional stats.Client.
func BumpAvg(c Client, key string, val float64) {
if c != nil {
c.BumpAvg(key, val)
}
}
// BumpSum calls BumpSum on the Client if it isn't nil. This is useful when a
// component has an optional stats.Client.
func BumpSum(c Client, key string, val float64) {
if c != nil {
c.BumpSum(key, val)
}
}
// BumpHistogram calls BumpHistogram on the Client if it isn't nil. This is
// useful when a component has an optional stats.Client.
func BumpHistogram(c Client, key string, val float64) {
if c != nil {
c.BumpHistogram(key, val)
}
}
// BumpTime calls BumpTime on the Client if it isn't nil. If the Client is nil
// it still returns a valid return value which will be a no-op. This is useful
// when a component has an optional stats.Client.
func BumpTime(c Client, key string) interface {
End()
} {
if c != nil {
return c.BumpTime(key)
}
return NoOpEnd
}
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