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66371f392a
We update profileManager to allow registering a single state (profile+prefs) change hook. This is to invert the dependency between the profileManager and the LocalBackend, so that instead of LocalBackend asking profileManager for the state, we can have profileManager call LocalBackend when the state changes. We also update feature.Hook with a new (*feature.Hook).GetOk method to avoid calling both IsSet and Get. Updates tailscale/corp#28014 Updates #12614 Signed-off-by: Nick Khyl <nickk@tailscale.com>
79 lines
1.8 KiB
Go
79 lines
1.8 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package feature tracks which features are linked into the binary.
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package feature
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import "reflect"
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var in = map[string]bool{}
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// Register notes that the named feature is linked into the binary.
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func Register(name string) {
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if _, ok := in[name]; ok {
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panic("duplicate feature registration for " + name)
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}
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in[name] = true
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}
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// Hook is a func that can only be set once.
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//
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// It is not safe for concurrent use.
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type Hook[Func any] struct {
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f Func
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ok bool
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}
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// IsSet reports whether the hook has been set.
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func (h *Hook[Func]) IsSet() bool {
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return h.ok
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}
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// Set sets the hook function, panicking if it's already been set
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// or f is the zero value.
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//
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// It's meant to be called in init.
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func (h *Hook[Func]) Set(f Func) {
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if h.ok {
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panic("Set on already-set feature hook")
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}
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if reflect.ValueOf(f).IsZero() {
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panic("Set with zero value")
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}
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h.f = f
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h.ok = true
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}
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// Get returns the hook function, or panics if it hasn't been set.
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// Use IsSet to check if it's been set.
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func (h *Hook[Func]) Get() Func {
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if !h.ok {
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panic("Get on unset feature hook, without IsSet")
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}
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return h.f
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}
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// GetOk returns the hook function and true if it has been set,
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// otherwise its zero value and false.
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func (h *Hook[Func]) GetOk() (f Func, ok bool) {
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return h.f, h.ok
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}
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// Hooks is a slice of funcs.
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//
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// As opposed to a single Hook, this is meant to be used when
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// multiple parties are able to install the same hook.
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type Hooks[Func any] []Func
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// Add adds a hook to the list of hooks.
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//
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// Add should only be called during early program
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// startup before Tailscale has started.
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// It is not safe for concurrent use.
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func (h *Hooks[Func]) Add(f Func) {
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if reflect.ValueOf(f).IsZero() {
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panic("Add with zero value")
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}
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*h = append(*h, f)
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}
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