113 lines
2.5 KiB
Go
113 lines
2.5 KiB
Go
package metrics
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import "sync/atomic"
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// Counters hold an int64 value that can be incremented and decremented.
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type Counter interface {
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Clear()
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Count() int64
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Dec(int64)
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Inc(int64)
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Snapshot() Counter
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}
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// GetOrRegisterCounter returns an existing Counter or constructs and registers
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// a new StandardCounter.
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func GetOrRegisterCounter(name string, r Registry) Counter {
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if nil == r {
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r = DefaultRegistry
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}
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return r.GetOrRegister(name, NewCounter).(Counter)
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}
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// NewCounter constructs a new StandardCounter.
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func NewCounter() Counter {
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if !Enabled {
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return NilCounter{}
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}
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return &StandardCounter{0}
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}
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// NewRegisteredCounter constructs and registers a new StandardCounter.
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func NewRegisteredCounter(name string, r Registry) Counter {
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c := NewCounter()
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if nil == r {
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r = DefaultRegistry
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}
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r.Register(name, c)
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return c
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}
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// CounterSnapshot is a read-only copy of another Counter.
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type CounterSnapshot int64
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// Clear panics.
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func (CounterSnapshot) Clear() {
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panic("Clear called on a CounterSnapshot")
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}
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// Count returns the count at the time the snapshot was taken.
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func (c CounterSnapshot) Count() int64 { return int64(c) }
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// Dec panics.
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func (CounterSnapshot) Dec(int64) {
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panic("Dec called on a CounterSnapshot")
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}
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// Inc panics.
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func (CounterSnapshot) Inc(int64) {
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panic("Inc called on a CounterSnapshot")
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}
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// Snapshot returns the snapshot.
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func (c CounterSnapshot) Snapshot() Counter { return c }
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// NilCounter is a no-op Counter.
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type NilCounter struct{}
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// Clear is a no-op.
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func (NilCounter) Clear() {}
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// Count is a no-op.
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func (NilCounter) Count() int64 { return 0 }
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// Dec is a no-op.
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func (NilCounter) Dec(i int64) {}
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// Inc is a no-op.
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func (NilCounter) Inc(i int64) {}
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// Snapshot is a no-op.
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func (NilCounter) Snapshot() Counter { return NilCounter{} }
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// StandardCounter is the standard implementation of a Counter and uses the
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// sync/atomic package to manage a single int64 value.
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type StandardCounter struct {
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count int64
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}
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// Clear sets the counter to zero.
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func (c *StandardCounter) Clear() {
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atomic.StoreInt64(&c.count, 0)
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}
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// Count returns the current count.
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func (c *StandardCounter) Count() int64 {
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return atomic.LoadInt64(&c.count)
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}
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// Dec decrements the counter by the given amount.
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func (c *StandardCounter) Dec(i int64) {
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atomic.AddInt64(&c.count, -i)
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}
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// Inc increments the counter by the given amount.
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func (c *StandardCounter) Inc(i int64) {
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atomic.AddInt64(&c.count, i)
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}
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// Snapshot returns a read-only copy of the counter.
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func (c *StandardCounter) Snapshot() Counter {
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return CounterSnapshot(c.Count())
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}
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