85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
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// Copyright (c) 2017 Arista Networks, Inc.
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// Use of this source code is governed by the Apache License 2.0
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// that can be found in the COPYING file.
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// This code was forked from the Go project, here's the original copyright header:
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package monitor
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import (
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"bytes"
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"expvar"
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"fmt"
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"sync"
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)
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// Map is a string-to-Var map variable that satisfies the Var interface.
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// This a streamlined, more efficient version of expvar.Map, that also
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// supports deletion.
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type Map struct {
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m sync.Map // map[string]expvar.Var
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}
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func (v *Map) String() string {
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var b bytes.Buffer
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b.WriteByte('{')
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first := true
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v.m.Range(func(k, value interface{}) bool {
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if !first {
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b.WriteString(", ")
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}
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fmt.Fprintf(&b, "%q: %v", k, value)
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first = false
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return true
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})
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b.WriteByte('}')
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return b.String()
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}
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// Get atomically returns the Var for the given key or nil.
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func (v *Map) Get(key string) expvar.Var {
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i, _ := v.m.Load(key)
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av, _ := i.(expvar.Var)
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return av
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}
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// Set atomically associates the given Var to the given key.
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func (v *Map) Set(key string, av expvar.Var) {
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// Before we store the value, check to see whether the key is new. Try a Load
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// before LoadOrStore: LoadOrStore causes the key interface to escape even on
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// the Load path.
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if _, ok := v.m.Load(key); !ok {
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if _, dup := v.m.LoadOrStore(key, av); !dup {
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return
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}
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}
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v.m.Store(key, av)
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}
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// Delete atomically deletes the given key if it exists.
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func (v *Map) Delete(key string) {
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v.m.Delete(key)
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}
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// Do calls f for each entry in the map.
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// The map is locked during the iteration,
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// but existing entries may be concurrently updated.
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func (v *Map) Do(f func(expvar.KeyValue)) {
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v.m.Range(func(k, value interface{}) bool {
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f(expvar.KeyValue{Key: k.(string), Value: value.(expvar.Var)})
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return true
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})
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}
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// NewMap creates a new Map and publishes it with the given name.
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func NewMap(name string) *Map {
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v := new(Map)
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expvar.Publish(name, v)
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return v
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}
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