Package evbus is the little and lightweight eventbus with async compatibility for GoLang.
Make sure that Go is installed on your computer. Type the following command in your terminal:
go get github.com/jarvanstack/evbus
After it the package is ready to use.
Add following line in your *.go
file:
import "github.com/jarvanstack/evbus"
If you unhappy to use long evbus
, you can do something like this:
import (
evbus "github.com/jarvanstack/evbus"
)
func calculator(a int, b int) {
fmt.Printf("%d\n", a + b)
}
func main() {
bus := evbus.New();
bus.Subscribe("main:calculator", calculator);
bus.Publish("main:calculator", 20, 40);
bus.Unsubscribe("main:calculator", calculator);
}
- New()
- Subscribe()
- SubscribeOnce()
- HasCallback()
- Unsubscribe()
- Publish()
- SubscribeAsync()
- SubscribeOnceAsync()
- WaitAsync()
New returns new evbus with empty handlers.
bus := evbus.New();
Subscribe to a topic. Returns error if fn
is not a function.
func Handler() { ... }
...
bus.Subscribe("topic:handler", Handler)
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)
Remove callback defined for a topic. Returns error if there are no callbacks subscribed to the topic.
bus.Unsubscribe("topic:handler", HelloWord);
Returns true if exists any callback subscribed to the topic.
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!");
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 := evbus.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 works like SubscribeOnce except the callback to executed asynchronously
WaitAsync waits for all async callbacks to complete.
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
var (
netAAddr = ":2050"
netAPath = "/_net_bus_A"
netBAddr = ":2055"
netBPath = "/_net_bus_B"
)
fmt.Printf("Start\n")
netA := NewNetworkBus(netAAddr, netAPath)
netA.Start()
netB := NewNetworkBus(netBAddr, netBPath)
netB.Start()
// netA 推送 netB 消费
netB.Subscribe("event1", func(a int) {
fmt.Printf("[netA 推送 netB 消费] %d \n", a)
}, netAAddr, netAPath)
netA.EventBus().Publish("event1", 10)
// netB 推送 netA 消费
netA.Subscribe("event2", func(a int) {
fmt.Printf("[netB 推送 netA 消费] %d \n", a)
}, netBAddr, netBPath)
netB.EventBus().Publish("event2", 10)
// netA 推送 netA 本地消费
netA.EventBus().Subscribe("event3", func(a int) {
fmt.Printf("[netA 推送 netA 本地消费] %d \n", a)
})
netA.EventBus().Publish("event3", 10)
// netA 推送 netA 本地查询
netA.EventBus().Subscribe("query1", func(result *int) {
*result = 10
return
})
var result int
netA.EventBus().Publish("query1", &result)
fmt.Printf("[netA 推送 netA 本地查询] %d \n", result)
// netA 推送 netB 查询 (panic)
// netB.Subscribe("query2", func(result *int) {
// *result = 10
// return
// }, netAAddr, netAPath)
// var result2 int
// netA.EventBus().Publish("query2", &result2)
// fmt.Printf("[netA 推送 netB 查询] %d \n", result2)
netA.Stop()
netB.Stop()
client.go
func main() {
client := NewClient(":2015", "/_client_bus_", New())
client.Start()
client.Subscribe("main:calculator", calculator, ":2010", "/_server_bus_")
// ...
client.Stop()
}
Documentation is available here: godoc.org. Full information about code coverage is also available here: evbus on gocover.io.
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)