examples for using expvar

expvar_examples.go

package main

import "fmt"
import "time"
import "expvar"
import "encoding/json"

type Nodes struct {
    peers map[string][]string
}

func (n *Nodes) AddPeer(node string, peer string) {
    n.peers[node] = append(n.peers[node], peer)
}

func (n *Nodes) String() string {
    str, _ := json.Marshal(n.peers)
    return string(str)
}

var (
    nodes *Nodes
)

func main() {
    nodes = &Nodes{peers: make(map[string][]string)}
    expvar.Publish("Nodes", nodes)

    go simulateAdd("node1", "node2", 1)
    go simulateAdd("node1", "node3", 3)
    go simulateAdd("node1", "node4", 5)
    go simulateAdd("node2", "node5", 4)
    go simulateAdd("node2", "node4", 4)
    go simulateAdd("node3", "node4", 3)

    time.Sleep(time.Second * time.Duration(8))

    newNodes := expvar.Get("Nodes").(*Nodes)
    fmt.Println(newNodes)

    fmt.Println("Done")
}

func simulateAdd(node string, peer string, waitTime int) {
    time.Sleep(time.Second * time.Duration(waitTime))
    nodes := expvar.Get("Nodes").(*Nodes)
    nodes.AddPeer(node, peer)
}