52 lines
983 B
Go
52 lines
983 B
Go
package missinggo
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import (
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"log"
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"runtime"
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"sync"
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"sync/atomic"
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)
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const debug = false
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// A Wolf represents some event that becomes less and less interesting as it
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// occurs. Call CryHeard to see if we should pay attention this time.
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type Wolf struct {
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cries uint64
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}
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// Returns true less and less often. Convenient for exponentially decreasing
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// the amount of noise due to errors.
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func (me *Wolf) CryHeard() bool {
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n := atomic.AddUint64(&me.cries, 1)
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return n&(n-1) == 0
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}
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var (
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mu sync.Mutex
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wolves map[uintptr]*Wolf
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)
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// Calls CryHeard() on a Wolf that is unique to the callers program counter.
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// i.e. every CryHeard() expression has its own Wolf.
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func CryHeard() bool {
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pc, file, line, ok := runtime.Caller(1)
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if debug {
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log.Println(pc, file, line, ok)
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}
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if !ok {
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return true
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}
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mu.Lock()
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if wolves == nil {
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wolves = make(map[uintptr]*Wolf)
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}
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w, ok := wolves[pc]
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if !ok {
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w = new(Wolf)
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wolves[pc] = w
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}
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mu.Unlock()
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return w.CryHeard()
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}
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