Marvin Preuss
15e245d433
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115 lines
3.0 KiB
Go
115 lines
3.0 KiB
Go
// Package workgroups is a little helper for creating workers
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// with the help of sync.Errgroup.
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//
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// (image/build) https://ci.xsfx.dev/api/badges/xsteadfastx/workgroups/status.svg
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// (image/coverage) https://codecov.io/gh/xsteadfastx/workgroups/branch/main/graph/badge.svg?token=RZE1ZWJSYA
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// (image/report) https://goreportcard.com/badge/go.xsfx.dev/workgroups
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// (image/reference) https://pkg.go.dev/badge/go.xsfx.dev/workgroups.svg
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//
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// (image/readme) ./README.gif
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package workgroups
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import (
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"context"
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"errors"
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"fmt"
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"github.com/rs/zerolog/log"
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"golang.org/x/sync/errgroup"
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)
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// ErrInWorker is an error that gets returned if there is a error
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// in the work function.
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var ErrInWorker = errors.New("received error in worker")
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// Work is a type that defines worker work.
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type Work func(ctx context.Context) error
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// Job carries a job with everything it needs.
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// I know know that contexts shouldnt be stored in a struct.
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// Here is an exception, because its a short living object.
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// The context is only used as argument for the Work function.
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// Please use the NewJob function to get around this context in struct shenanigans.
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type Job struct {
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ctx context.Context
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work Work
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}
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// NewJob creates a new Job to send down the work queue with context and all that stuff.
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func NewJob(ctx context.Context, work Work) Job {
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return Job{ctx, work}
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}
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// Dispatcher carries the job queue, the errgroup and the number of workers
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// to start.
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type Dispatcher struct {
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queue chan Job
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eg *errgroup.Group
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numWorkers int
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}
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// NewDispatcher creates a new Dispatcher.
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// It takes a context and adds it to the errgroup creation and returns it again.
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func NewDispatcher(ctx context.Context, numWorkers int) (*Dispatcher, context.Context) {
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eg, ctx := errgroup.WithContext(ctx)
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return &Dispatcher{
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queue: make(chan Job, numWorkers),
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eg: eg,
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numWorkers: numWorkers,
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}, ctx
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}
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// Start starts the configured number of workers and waits for jobs.
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func (d *Dispatcher) Start() {
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for i := 0; i < d.numWorkers; i++ {
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logger := log.With().Caller().Int("worker", i).Logger()
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logger.Info().Msg("starting worker")
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d.eg.Go(func() error {
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for j := range d.queue {
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errChan := make(chan error)
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go func() {
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errChan <- j.work(j.ctx)
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}()
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select {
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case <-j.ctx.Done():
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return fmt.Errorf("got error from context: %w", j.ctx.Err())
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case err := <-errChan:
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if err != nil {
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return fmt.Errorf("go error from work function: %w", err)
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}
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}
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}
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logger.Info().Msg("no work. returning...")
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return nil
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})
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}
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}
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// Append adds a job to the work queue.
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func (d *Dispatcher) Append(job Job) {
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log.Debug().Msg("adds job")
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d.queue <- job
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}
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// Close closes the queue channel.
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func (d *Dispatcher) Close() {
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log.Debug().Msg("closing queue")
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close(d.queue)
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}
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func (d *Dispatcher) Wait() error {
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log.Debug().Msg("waiting for jobs to finnish")
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if err := d.eg.Wait(); err != nil {
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return fmt.Errorf("error on waiting: %w", err)
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}
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return nil
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}
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