EventBus
This is a modified version of asaskevich/EventBus. The primary differences are:
- Removed all references to fmt, replacing with log or errors when relevant. This reduces build output by ~7MB.
- Converted to a go module.
- Travic-CI updates.
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/coreybutler/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.
contributors
Special thanks to- Brian Downs
- Dominik Schulz
- bennAH
- [John Noble] (https://github.com/gaxunil)
- [Evan Borgstrom] (https://github.com/borgstrom)