63 lines
1.8 KiB
Go
63 lines
1.8 KiB
Go
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// Package run implements an actor-runner with deterministic teardown. It is
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// somewhat similar to package errgroup, except it does not require actor
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// goroutines to understand context semantics. This makes it suitable for use in
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// more circumstances; for example, goroutines which are handling connections
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// from net.Listeners, or scanning input from a closable io.Reader.
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package run
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// Group collects actors (functions) and runs them concurrently.
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// When one actor (function) returns, all actors are interrupted.
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// The zero value of a Group is useful.
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type Group struct {
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actors []actor
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}
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// Add an actor (function) to the group. Each actor must be pre-emptable by an
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// interrupt function. That is, if interrupt is invoked, execute should return.
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// Also, it must be safe to call interrupt even after execute has returned.
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//
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// The first actor (function) to return interrupts all running actors.
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// The error is passed to the interrupt functions, and is returned by Run.
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func (g *Group) Add(execute func() error, interrupt func(error)) {
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g.actors = append(g.actors, actor{execute, interrupt})
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}
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// Run all actors (functions) concurrently.
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// When the first actor returns, all others are interrupted.
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// Run only returns when all actors have exited.
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// Run returns the error returned by the first exiting actor.
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func (g *Group) Run() error {
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if len(g.actors) == 0 {
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return nil
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}
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// Run each actor.
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errors := make(chan error, len(g.actors))
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for _, a := range g.actors {
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go func(a actor) {
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errors <- a.execute()
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}(a)
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}
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// Wait for the first actor to stop.
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err := <-errors
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// Signal all actors to stop.
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for _, a := range g.actors {
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a.interrupt(err)
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}
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// Wait for all actors to stop.
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for i := 1; i < cap(errors); i++ {
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<-errors
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}
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// Return the original error.
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return err
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}
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type actor struct {
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execute func() error
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interrupt func(error)
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}
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