package task import ( "context" "v2ray.com/core/common/signal/semaphore" ) type Task func() error type executionContext struct { ctx context.Context tasks []Task onSuccess Task onFailure Task } func (c *executionContext) executeTask() error { if len(c.tasks) == 0 { return nil } ctx := context.Background() if c.ctx != nil { ctx = c.ctx } return executeParallel(ctx, c.tasks) } func (c *executionContext) run() error { err := c.executeTask() if err == nil && c.onSuccess != nil { return c.onSuccess() } if err != nil && c.onFailure != nil { return c.onFailure() } return err } type ExecutionOption func(*executionContext) func WithContext(ctx context.Context) ExecutionOption { return func(c *executionContext) { c.ctx = ctx } } func Parallel(tasks ...Task) ExecutionOption { return func(c *executionContext) { c.tasks = append(c.tasks, tasks...) } } func Sequential(tasks ...Task) ExecutionOption { return func(c *executionContext) { if len(tasks) == 0 { return } if len(tasks) == 1 { c.tasks = append(c.tasks, tasks[0]) return } c.tasks = append(c.tasks, func() error { return execute(tasks...) }) } } func OnSuccess(task Task) ExecutionOption { return func(c *executionContext) { c.onSuccess = task } } func OnFailure(task Task) ExecutionOption { return func(c *executionContext) { c.onFailure = task } } func Single(task Task, opts ExecutionOption) Task { return Run(append([]ExecutionOption{Sequential(task)}, opts)...) } func Run(opts ...ExecutionOption) Task { var c executionContext for _, opt := range opts { opt(&c) } return func() error { return c.run() } } // execute runs a list of tasks sequentially, returns the first error encountered or nil if all tasks pass. func execute(tasks ...Task) error { for _, task := range tasks { if err := task(); err != nil { return err } } return nil } // executeParallel executes a list of tasks asynchronously, returns the first error encountered or nil if all tasks pass. func executeParallel(ctx context.Context, tasks []Task) error { n := len(tasks) s := semaphore.New(n) done := make(chan error, 1) for _, task := range tasks { <-s.Wait() go func(f func() error) { if err := f(); err != nil { select { case done <- err: default: } } s.Signal() }(task) } for i := 0; i < n; i++ { select { case err := <-done: return err case <-ctx.Done(): return ctx.Err() case <-s.Wait(): } } return nil }