micro/function.go

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// +build ignore
package micro
import (
"context"
"time"
"go.unistack.org/micro/v3/server"
)
// Function is a one time executing Service
type Function interface {
// Inherits Service interface
Service
// Done signals to complete execution
Done() error
// Handle registers an RPC handler
Handle(v interface{}) error
// Subscribe registers a subscriber
Subscribe(topic string, v interface{}) error
}
type function struct {
cancel context.CancelFunc
Service
}
// NewFunction returns a new Function for a one time executing Service
func NewFunction(opts ...Option) Function {
return newFunction(opts...)
}
func fnHandlerWrapper(f Function) server.HandlerWrapper {
return func(h server.HandlerFunc) server.HandlerFunc {
return func(ctx context.Context, req server.Request, rsp interface{}) error {
defer f.Done()
return h(ctx, req, rsp)
}
}
}
func fnSubWrapper(f Function) server.SubscriberWrapper {
return func(s server.SubscriberFunc) server.SubscriberFunc {
return func(ctx context.Context, msg server.Message) error {
defer f.Done()
return s(ctx, msg)
}
}
}
func newFunction(opts ...Option) Function {
ctx, cancel := context.WithCancel(context.Background())
// force ttl/interval
fopts := []Option{
RegisterTTL(time.Minute),
RegisterInterval(time.Second * 30),
}
// prepend to opts
fopts = append(fopts, opts...)
// make context the last thing
fopts = append(fopts, Context(ctx))
service := &service{opts: NewOptions(fopts...)}
fn := &function{
cancel: cancel,
Service: service,
}
service.Server().Init(
// ensure the service waits for requests to finish
server.Wait(nil),
// wrap handlers and subscribers to finish execution
server.WrapHandler(fnHandlerWrapper(fn)),
server.WrapSubscriber(fnSubWrapper(fn)),
)
return fn
}
func (f *function) Done() error {
f.cancel()
return nil
}
func (f *function) Handle(v interface{}) error {
return f.Service.Server().Handle(
f.Service.Server().NewHandler(v),
)
}
func (f *function) Subscribe(topic string, v interface{}) error {
return f.Service.Server().Subscribe(
f.Service.Server().NewSubscriber(topic, v),
)
}