README
¶
EventBus
Package EventBus is the little and lightweight eventbus with async compatibility for GoLang.
Installation
Make sure that Go is installed on your computer. Type the following command in your terminal:
go get github.com/asaskevich/EventBus
After it the package is ready to use.
Import package in your project
Add following line in your *.go file:
import "github.com/asaskevich/EventBus"
If you unhappy to use long EventBus, you can do something like this:
import (
evbus "github.com/asaskevich/EventBus"
)
Example
func calculator(a int, b int) {
fmt.Printf("%d\n", a + b)
}
func main() {
bus := EventBus.New();
bus.Subscribe("main:calculator", calculator);
bus.Publish("main:calculator", 20, 40);
bus.Unsubscribe("main:calculator", calculator);
}
Implemented methods
- New()
- Subscribe()
- SubscribeOnce()
- HasCallback()
- Unsubscribe()
- Publish()
- SubscribeAsync()
- SubscribeOnceAsync()
- WaitAsync()
New()
New returns new EventBus with empty handlers.
bus := EventBus.New();
Subscribe(topic string, fn interface{}) error
Subscribe to a topic. Returns error if fn is not a function.
func Handler() { ... }
...
bus.Subscribe("topic:handler", Handler)
SubscribeOnce(topic string, fn interface{}) error
Subscribe to a topic once. Handler will be removed after executing. Returns error if fn is not a function.
func HelloWorld() { ... }
...
bus.SubscribeOnce("topic:handler", HelloWorld)
Unsubscribe(topic string, fn interface{}) error
Remove callback defined for a topic. Returns error if there are no callbacks subscribed to the topic.
bus.Unsubscribe("topic:handler", HelloWord);
HasCallback(topic string) bool
Returns true if exists any callback subscribed to the topic.
Publish(topic string, args ...interface{})
Publish executes callback defined for a topic. Any additional argument will be transferred to the callback.
func Handler(str string) { ... }
...
bus.Subscribe("topic:handler", Handler)
...
bus.Publish("topic:handler", "Hello, World!");
SubscribeAsync(topic string, fn interface{}, transactional bool)
Subscribe to a topic with an asynchronous callback. Returns error if fn is not a function.
func slowCalculator(a, b int) {
time.Sleep(3 * time.Second)
fmt.Printf("%d\n", a + b)
}
bus := EventBus.New()
bus.SubscribeAsync("main:slow_calculator", slowCalculator, false)
bus.Publish("main:slow_calculator", 20, 60)
fmt.Println("start: do some stuff while waiting for a result")
fmt.Println("end: do some stuff while waiting for a result")
bus.WaitAsync() // wait for all async callbacks to complete
fmt.Println("do some stuff after waiting for result")
Transactional determines whether subsequent callbacks for a topic are run serially (true) or concurrently(false)
SubscribeOnceAsync(topic string, args ...interface{})
SubscribeOnceAsync works like SubscribeOnce except the callback to executed asynchronously
WaitAsync()
WaitAsync waits for all async callbacks to complete.
Cross Process Events
Works with two rpc services:
- a client service to listen to remotely published events from a server
- a server service to listen to client subscriptions
server.go
func main() {
server := NewServer(":2010", "/_server_bus_", New())
server.Start()
// ...
server.EventBus().Publish("main:calculator", 4, 6)
// ...
server.Stop()
}
client.go
func main() {
client := NewClient(":2015", "/_client_bus_", New())
client.Start()
client.Subscribe("main:calculator", calculator, ":2010", "/_server_bus_")
// ...
client.Stop()
}
Notes
Documentation is available here: godoc.org. Full information about code coverage is also available here: EventBus on gocover.io.
Support
If you do have a contribution for the package feel free to put up a Pull Request or open Issue.
Special thanks to contributors
- Brian Downs
- Dominik Schulz
- bennAH
- [John Noble] (https://github.com/gaxunil)
- [Evan Borgstrom] (https://github.com/borgstrom)
Documentation
¶
Index ¶
- Constants
- type Bus
- type BusController
- type BusPublisher
- type BusSubscriber
- type Client
- type ClientArg
- type ClientService
- type EventBus
- func (bus *EventBus) GetQueueSize() int64
- func (bus *EventBus) HasCallback(topic string) bool
- func (bus *EventBus) Publish(topic string, args ...interface{})
- func (bus *EventBus) Subscribe(topic string, fn interface{}) error
- func (bus *EventBus) SubscribeAsync(topic string, fn interface{}, transactional bool) error
- func (bus *EventBus) SubscribeOnce(topic string, fn interface{}) error
- func (bus *EventBus) SubscribeOnceAsync(topic string, fn interface{}) error
- func (bus *EventBus) Unsubscribe(topic string, handler interface{}) error
- func (bus *EventBus) WaitAsync()
- type NetworkBus
- type NetworkBusService
- type Server
- type ServerService
- type SubscribeArg
- type SubscribeType
Constants ¶
const (
// PublishService - Client service method
PublishService = "ClientService.PushEvent"
)
const (
// RegisterService - Server subscribe service method
RegisterService = "ServerService.Register"
)
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Bus ¶
type Bus interface {
BusController
BusSubscriber
BusPublisher
}
Bus englobes global (subscribe, publish, control) bus behavior
type BusController ¶
BusController defines bus control behavior (checking handler's presence, synchronization)
type BusPublisher ¶
type BusPublisher interface {
Publish(topic string, args ...interface{})
}
BusPublisher defines publishing-related bus behavior
type BusSubscriber ¶
type BusSubscriber interface {
Subscribe(topic string, fn interface{}) error
SubscribeAsync(topic string, fn interface{}, transactional bool) error
SubscribeOnce(topic string, fn interface{}) error
SubscribeOnceAsync(topic string, fn interface{}) error
Unsubscribe(topic string, handler interface{}) error
}
BusSubscriber defines subscription-related bus behavior
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client - object capable of subscribing to a remote event bus
func (*Client) SubscribeOnce ¶
SubscribeOnce subscribes once to a topic in a remote event bus
type ClientArg ¶
type ClientArg struct {
Args []interface{}
Topic string
}
ClientArg - object containing event for client to publish locally
type ClientService ¶
type ClientService struct {
// contains filtered or unexported fields
}
ClientService - service object listening to events published in a remote event bus
type EventBus ¶
type EventBus struct {
// contains filtered or unexported fields
}
EventBus - box for handlers and callbacks.
func (*EventBus) GetQueueSize ¶ added in v1.0.1
func (*EventBus) HasCallback ¶
HasCallback returns true if exists any callback subscribed to the topic.
func (*EventBus) Publish ¶
Publish executes callback defined for a topic. Any additional argument will be transferred to the callback.
func (*EventBus) Subscribe ¶
Subscribe subscribes to a topic. Returns error if `fn` is not a function.
func (*EventBus) SubscribeAsync ¶
SubscribeAsync subscribes to a topic with an asynchronous callback Transactional determines whether subsequent callbacks for a topic are run serially (true) or concurrently (false) Returns error if `fn` is not a function.
func (*EventBus) SubscribeOnce ¶
SubscribeOnce subscribes to a topic once. Handler will be removed after executing. Returns error if `fn` is not a function.
func (*EventBus) SubscribeOnceAsync ¶
SubscribeOnceAsync subscribes to a topic once with an asynchronous callback Handler will be removed after executing. Returns error if `fn` is not a function.
func (*EventBus) Unsubscribe ¶
Unsubscribe removes callback defined for a topic. Returns error if there are no callbacks subscribed to the topic.
type NetworkBus ¶
NetworkBus - object capable of subscribing to remote event buses in addition to remote event busses subscribing to it's local event bus. Compoed of a server and client
func NewNetworkBus ¶
func NewNetworkBus(address, path string) *NetworkBus
NewNetworkBus - returns a new network bus object at the server address and path
func (*NetworkBus) EventBus ¶
func (networkBus *NetworkBus) EventBus() Bus
EventBus - returns wrapped event bus
func (*NetworkBus) Start ¶
func (networkBus *NetworkBus) Start() error
Start - helper method to serve a network bus service
func (*NetworkBus) Stop ¶
func (networkBus *NetworkBus) Stop()
Stop - signal for the service to stop serving
type NetworkBusService ¶
type NetworkBusService struct {
// contains filtered or unexported fields
}
NetworkBusService - object capable of serving the network bus
type Server ¶
type Server struct {
// contains filtered or unexported fields
}
Server - object capable of being subscribed to by remote handlers
func (*Server) HasClientSubscribed ¶
func (server *Server) HasClientSubscribed(arg *SubscribeArg) bool
HasClientSubscribed - True if a client subscribed to this server with the same topic
type ServerService ¶
type ServerService struct {
// contains filtered or unexported fields
}
ServerService - service object to listen to remote subscriptions
func (*ServerService) Register ¶
func (service *ServerService) Register(arg *SubscribeArg, success *bool) error
Register - Registers a remote handler to this event bus for a remote subscribe - a given client address only needs to subscribe once event will be republished in local event bus
type SubscribeArg ¶
type SubscribeArg struct {
ClientAddr string
ClientPath string
ServiceMethod string
SubscribeType SubscribeType
Topic string
}
SubscribeArg - object to hold subscribe arguments from remote event handlers
type SubscribeType ¶
type SubscribeType int
SubscribeType - how the client intends to subscribe
const ( // Subscribe - subscribe to all events Subscribe SubscribeType = iota // SubscribeOnce - subscribe to only one event SubscribeOnce )
Source Files