148 lines
4.4 KiB
Go
148 lines
4.4 KiB
Go
// Copyright (c) 2022 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package fx
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import (
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"context"
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"go.uber.org/fx/internal/lifecycle"
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)
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// A HookFunc is a function that can be used as a [Hook].
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type HookFunc interface {
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~func() | ~func() error | ~func(context.Context) | ~func(context.Context) error
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}
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// Lifecycle allows constructors to register callbacks that are executed on
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// application start and stop. See the documentation for App for details on Fx
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// applications' initialization, startup, and shutdown logic.
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type Lifecycle interface {
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Append(Hook)
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}
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// A Hook is a pair of start and stop callbacks, either of which can be nil.
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// If a Hook's OnStart callback isn't executed (because a previous OnStart
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// failure short-circuited application startup), its OnStop callback won't be
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// executed.
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type Hook struct {
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OnStart func(context.Context) error
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OnStop func(context.Context) error
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onStartName string
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onStopName string
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}
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// StartHook returns a new Hook with start as its [Hook.OnStart] function,
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// wrapping its signature as needed. For example, given the following function:
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//
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// func myhook() {
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// fmt.Println("hook called")
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// }
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//
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// then calling:
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//
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// lifecycle.Append(StartHook(myfunc))
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//
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// is functionally equivalent to calling:
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//
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// lifecycle.Append(fx.Hook{
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// OnStart: func(context.Context) error {
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// myfunc()
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// return nil
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// },
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// })
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//
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// The same is true for all functions that satisfy the HookFunc constraint.
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// Note that any context.Context parameter or error return will be propagated
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// as expected. If propagation is not intended, users should instead provide a
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// closure that discards the undesired value(s), or construct a Hook directly.
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func StartHook[T HookFunc](start T) Hook {
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onstart, startname := lifecycle.Wrap(start)
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return Hook{
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OnStart: onstart,
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onStartName: startname,
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}
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}
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// StopHook returns a new Hook with stop as its [Hook.OnStop] function,
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// wrapping its signature as needed. For example, given the following function:
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//
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// func myhook() {
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// fmt.Println("hook called")
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// }
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//
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// then calling:
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//
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// lifecycle.Append(StopHook(myfunc))
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//
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// is functionally equivalent to calling:
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//
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// lifecycle.Append(fx.Hook{
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// OnStop: func(context.Context) error {
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// myfunc()
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// return nil
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// },
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// })
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//
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// The same is true for all functions that satisfy the HookFunc constraint.
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// Note that any context.Context parameter or error return will be propagated
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// as expected. If propagation is not intended, users should instead provide a
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// closure that discards the undesired value(s), or construct a Hook directly.
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func StopHook[T HookFunc](stop T) Hook {
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onstop, stopname := lifecycle.Wrap(stop)
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return Hook{
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OnStop: onstop,
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onStopName: stopname,
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}
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}
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// StartStopHook returns a new Hook with start as its [Hook.OnStart] function
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// and stop as its [Hook.OnStop] function, independently wrapping the signature
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// of each as needed.
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func StartStopHook[T1 HookFunc, T2 HookFunc](start T1, stop T2) Hook {
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var (
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onstart, startname = lifecycle.Wrap(start)
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onstop, stopname = lifecycle.Wrap(stop)
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)
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return Hook{
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OnStart: onstart,
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OnStop: onstop,
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onStartName: startname,
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onStopName: stopname,
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}
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}
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type lifecycleWrapper struct {
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*lifecycle.Lifecycle
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}
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func (l *lifecycleWrapper) Append(h Hook) {
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l.Lifecycle.Append(lifecycle.Hook{
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OnStart: h.OnStart,
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OnStop: h.OnStop,
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OnStartName: h.onStartName,
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OnStopName: h.onStopName,
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})
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}
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