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bus.go
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bus.go
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package bus
import (
"context"
"errors"
"reflect"
)
type HandlerFunc interface{}
type CtxHandlerFunc func()
type Msg interface{}
var ErrHandlerNotFound = errors.New("handler not found")
type Bus interface {
Dispatch(msg Msg) error
DispatchCtx(ctx context.Context, msg Msg) error
Publish(msg Msg) error
AddHandler(handler HandlerFunc)
AddCtxHandler(handler HandlerFunc)
AddEventListener(handler HandlerFunc)
AddWildcardListener(handler HandlerFunc)
}
type InProcBus struct {
handlers map[string]HandlerFunc
listeners map[string][]HandlerFunc
wildcardListeners []HandlerFunc
}
// temp stuff, not sure how to handle bus instance, and init yet
var globalBus = New()
func New() Bus {
bus := &InProcBus{}
bus.handlers = make(map[string]HandlerFunc)
bus.listeners = make(map[string][]HandlerFunc)
bus.wildcardListeners = make([]HandlerFunc, 0)
return bus
}
// Want to get rid of global bus
func GetBus() Bus {
return globalBus
}
func (b *InProcBus) DispatchCtx(ctx context.Context, msg Msg) error {
var msgName = reflect.TypeOf(msg).Elem().Name()
var handler = b.handlers[msgName]
if handler == nil {
return ErrHandlerNotFound
}
var params = make([]reflect.Value, 2)
params[0] = reflect.ValueOf(ctx)
params[1] = reflect.ValueOf(msg)
ret := reflect.ValueOf(handler).Call(params)
err := ret[0].Interface()
if err == nil {
return nil
}
return err.(error)
}
func (b *InProcBus) Dispatch(msg Msg) error {
var msgName = reflect.TypeOf(msg).Elem().Name()
var handler = b.handlers[msgName]
if handler == nil {
return ErrHandlerNotFound
}
var params = make([]reflect.Value, 1)
params[0] = reflect.ValueOf(msg)
ret := reflect.ValueOf(handler).Call(params)
err := ret[0].Interface()
if err == nil {
return nil
}
return err.(error)
}
func (b *InProcBus) Publish(msg Msg) error {
var msgName = reflect.TypeOf(msg).Elem().Name()
var listeners = b.listeners[msgName]
var params = make([]reflect.Value, 1)
params[0] = reflect.ValueOf(msg)
for _, listenerHandler := range listeners {
ret := reflect.ValueOf(listenerHandler).Call(params)
err := ret[0].Interface()
if err != nil {
return err.(error)
}
}
for _, listenerHandler := range b.wildcardListeners {
ret := reflect.ValueOf(listenerHandler).Call(params)
err := ret[0].Interface()
if err != nil {
return err.(error)
}
}
return nil
}
func (b *InProcBus) AddWildcardListener(handler HandlerFunc) {
b.wildcardListeners = append(b.wildcardListeners, handler)
}
func (b *InProcBus) AddHandler(handler HandlerFunc) {
handlerType := reflect.TypeOf(handler)
queryTypeName := handlerType.In(0).Elem().Name()
b.handlers[queryTypeName] = handler
}
func (b *InProcBus) AddCtxHandler(handler HandlerFunc) {
handlerType := reflect.TypeOf(handler)
queryTypeName := handlerType.In(1).Elem().Name()
b.handlers[queryTypeName] = handler
}
func (b *InProcBus) AddEventListener(handler HandlerFunc) {
handlerType := reflect.TypeOf(handler)
eventName := handlerType.In(0).Elem().Name()
_, exists := b.listeners[eventName]
if !exists {
b.listeners[eventName] = make([]HandlerFunc, 0)
}
b.listeners[eventName] = append(b.listeners[eventName], handler)
}
// Package level functions
func AddHandler(implName string, handler HandlerFunc) {
globalBus.AddHandler(handler)
}
// Package level functions
func AddCtxHandler(implName string, handler HandlerFunc) {
globalBus.AddCtxHandler(handler)
}
// Package level functions
func AddEventListener(handler HandlerFunc) {
globalBus.AddEventListener(handler)
}
func AddWildcardListener(handler HandlerFunc) {
globalBus.AddWildcardListener(handler)
}
func Dispatch(msg Msg) error {
return globalBus.Dispatch(msg)
}
func DispatchCtx(ctx context.Context, msg Msg) error {
return globalBus.DispatchCtx(ctx, msg)
}
func Publish(msg Msg) error {
return globalBus.Publish(msg)
}
func ClearBusHandlers() {
globalBus = New()
}