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// Copyright 2024 Bjørn Erik Pedersen
// SPDX-License-Identifier: MIT
package parahelpers
import (
"context"
"golang.org/x/sync/errgroup"
)
// Group is a group of workers that can be used to enqueue work and wait for
// them to finish.
type Group[T any] interface {
Enqueue(T) error
Wait() error
}
type runGroup[T any] struct {
ctx context.Context
g *errgroup.Group
ch chan T
}
// GroupConfig is the configuration for a new Group.
type GroupConfig[T any] struct {
NumWorkers int
Handle func(context.Context, T) error
}
// RunGroup creates a new Group with the given configuration.
func RunGroup[T any](ctx context.Context, cfg GroupConfig[T]) Group[T] {
if cfg.NumWorkers <= 0 {
cfg.NumWorkers = 1
}
if cfg.Handle == nil {
panic("Handle must be set")
}
g, ctx := errgroup.WithContext(ctx)
// Buffered for performance.
ch := make(chan T, cfg.NumWorkers)
for i := 0; i < cfg.NumWorkers; i++ {
g.Go(func() error {
for {
select {
case <-ctx.Done():
return nil
case v, ok := <-ch:
if !ok {
return nil
}
if err := cfg.Handle(ctx, v); err != nil {
return err
}
}
}
})
}
return &runGroup[T]{
ctx: ctx,
g: g,
ch: ch,
}
}
// Enqueue enqueues a new item to be handled by the workers.
func (r *runGroup[T]) Enqueue(t T) error {
select {
case <-r.ctx.Done():
return nil
case r.ch <- t:
}
return nil
}
// Wait waits for all workers to finish and returns the first error.
func (r *runGroup[T]) Wait() error {
close(r.ch)
return r.g.Wait()
}
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