discarded host handler

discarded-host.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"sync"
+	"time"
+)
+
+type DiscardedHost struct {
+	*Connection
+	Host  string
+	Tries int
+}
+
+type DiscardedHostHandler struct {
+	mu           sync.RWMutex
+	port         int
+	hosts        []*DiscardedHost
+	onConnection *func(string)
+}
+
+func (d *DiscardedHostHandler) run() {
+	for range time.Tick(time.Second) {
+		d.mu.RLock()
+		lst := make([]*DiscardedHost, 0, len(d.hosts))
+		for _, host := range d.hosts {
+			if host.Tries >= 0 || host.Tries < 5 {
+				go d.testConnection(host)
+				lst = append(lst, host)
+			}
+		}
+		d.mu.RUnlock()
+		d.mu.Lock()
+		d.hosts = lst
+		d.mu.Unlock()
+	}
+
+}
+
+func (d *DiscardedHostHandler) testConnection(host *DiscardedHost) {
+	addr := fmt.Sprintf("%s:%d", host.Host, d.port)
+	conn, err := net.Dial("tcp", addr)
+
+	if err != nil {
+		host.Tries++
+		host.Tries = -1
+	} else {
+		conn.Close()
+		if d.onConnection != nil {
+			fn := *d.onConnection
+			fn(host.Host)
+		}
+	}
+}
+
+func NewDiscardedHostHandler(port int) *DiscardedHostHandler {
+	ret := &DiscardedHostHandler{
+		hosts: make([]*DiscardedHost, 0),
+		port:  port,
+	}
+	go ret.run()
+	return ret
+}
+
+func (d *DiscardedHostHandler) SetReconnectHandler(fn func(string)) {
+	d.onConnection = &fn
+}
+
+func (d *DiscardedHostHandler) AppendHost(host string) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	log.Printf("Retrying host %s", host)
+	d.hosts = append(d.hosts, &DiscardedHost{
+		Host:  host,
+		Tries: 0,
+	})
+}