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https://github.com/tailscale/tailscale.git
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72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
// Copyright (c) 2021 Tailscale Inc & 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 health is a registry for other packages to report & check
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// overall health status of the node.
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package health
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import (
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"sync"
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)
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var (
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mu sync.Mutex
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m = map[string]error{} // error key => err (or nil for no error)
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watchers = map[*watchHandle]func(string, error){} // opt func to run if error state changes
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)
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type watchHandle byte
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// RegisterWatcher adds a function that will be called if an
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// error changes state either to unhealthy or from unhealthy. It is
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// not called on transition from unknown to healthy. It must be non-nil
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// and is run in its own goroutine. The returned func unregisters it.
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func RegisterWatcher(cb func(errKey string, err error)) (unregister func()) {
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mu.Lock()
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defer mu.Unlock()
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handle := new(watchHandle)
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watchers[handle] = cb
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return func() {
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mu.Lock()
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defer mu.Unlock()
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delete(watchers, handle)
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}
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}
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// SetRouter sets the state of the wgengine/router.Router.
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func SetRouterHealth(err error) { set("router", err) }
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// RouterHealth returns the wgengine/router.Router error state.
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func RouterHealth() error { return get("router") }
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func get(key string) error {
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mu.Lock()
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defer mu.Unlock()
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return m[key]
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}
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func set(key string, err error) {
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mu.Lock()
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defer mu.Unlock()
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old, ok := m[key]
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if !ok && err == nil {
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// Initial happy path.
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m[key] = nil
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return
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}
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if ok && (old == nil) == (err == nil) {
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// No change in overall error status (nil-vs-not), so
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// don't run callbacks, but exact error might've
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// changed, so note it.
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if err != nil {
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m[key] = err
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}
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return
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}
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m[key] = err
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for _, cb := range watchers {
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go cb(key, err)
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}
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}
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