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|
package worker
import (
"context"
"errors"
"log/slog"
"time"
"golang.org/x/sync/errgroup"
)
type (
// Task defines a long running core component of the application.
Task interface {
// Start defines when the component will be started.
// The task MUST watch for the context and return when the context is
// canceled.
//
// Start MUST only error on unhandled catastrophic errors, since
// returning an error will cause the application to halt.
//
// Context canceled error is ignored and not reported as error as they
// will be trigger by OS signals or some other component erring. But in
// any case the task SHOULD handle and return context cancellation
// error.
Start(context.Context) error
}
// TaskPool manages the life-cycle of a pool of tasks.
TaskPool struct {
tasks []*work
}
// work is wrapper around task to add metadata to it.
work struct {
Name string
Task Task
wait time.Duration
}
)
func NewTaskPool() *TaskPool {
return &TaskPool{}
}
func (w *work) run(ctx context.Context) error {
// first time fire the task from the get go
timer := time.NewTimer(time.Nanosecond)
for {
select {
case <-ctx.Done():
return ctx.Err()
case <-timer.C:
if err := w.Task.Start(ctx); err != nil {
return err
}
}
timer.Reset(w.wait)
}
}
func (self *TaskPool) AddTask(name string, wait time.Duration, task Task) {
self.tasks = append(self.tasks, &work{
Name: name,
Task: task,
wait: wait,
})
}
func (self *TaskPool) Start(ctx context.Context) error {
var g errgroup.Group
ctx, cancel := context.WithCancel(ctx)
defer cancel()
for _, w := range self.tasks {
g.Go(func(w *work) func() error {
return func() error {
slog.Info("Process starting", "name", w.Name)
now := time.Now()
if err := w.run(ctx); err != nil && !errors.Is(context.Canceled, err) {
since := time.Since(now)
slog.Error(
"Process erred",
"name", w.Name,
"error", err,
"duration", since,
)
cancel()
return err
} else {
since := time.Since(now)
slog.Info(
"Process ended",
"name", w.Name,
"duration", since,
)
}
return nil
}
}(w))
}
return g.Wait()
}
|
