Adding dep files and dependencies.

vendor/github.com/samuel/go-zookeeper/zk/dnshostprovider.go

@@ -0,0 +1,88 @@
+package zk
+
+import (
+	"fmt"
+	"net"
+	"sync"
+)
+
+// DNSHostProvider is the default HostProvider. It currently matches
+// the Java StaticHostProvider, resolving hosts from DNS once during
+// the call to Init.  It could be easily extended to re-query DNS
+// periodically or if there is trouble connecting.
+type DNSHostProvider struct {
+	mu         sync.Mutex // Protects everything, so we can add asynchronous updates later.
+	servers    []string
+	curr       int
+	last       int
+	lookupHost func(string) ([]string, error) // Override of net.LookupHost, for testing.
+}
+
+// Init is called first, with the servers specified in the connection
+// string. It uses DNS to look up addresses for each server, then
+// shuffles them all together.
+func (hp *DNSHostProvider) Init(servers []string) error {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+
+	lookupHost := hp.lookupHost
+	if lookupHost == nil {
+		lookupHost = net.LookupHost
+	}
+
+	found := []string{}
+	for _, server := range servers {
+		host, port, err := net.SplitHostPort(server)
+		if err != nil {
+			return err
+		}
+		addrs, err := lookupHost(host)
+		if err != nil {
+			return err
+		}
+		for _, addr := range addrs {
+			found = append(found, net.JoinHostPort(addr, port))
+		}
+	}
+
+	if len(found) == 0 {
+		return fmt.Errorf("No hosts found for addresses %q", servers)
+	}
+
+	// Randomize the order of the servers to avoid creating hotspots
+	stringShuffle(found)
+
+	hp.servers = found
+	hp.curr = -1
+	hp.last = -1
+
+	return nil
+}
+
+// Len returns the number of servers available
+func (hp *DNSHostProvider) Len() int {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	return len(hp.servers)
+}
+
+// Next returns the next server to connect to. retryStart will be true
+// if we've looped through all known servers without Connected() being
+// called.
+func (hp *DNSHostProvider) Next() (server string, retryStart bool) {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	hp.curr = (hp.curr + 1) % len(hp.servers)
+	retryStart = hp.curr == hp.last
+	if hp.last == -1 {
+		hp.last = 0
+	}
+	return hp.servers[hp.curr], retryStart
+}
+
+// Connected notifies the HostProvider of a successful connection.
+func (hp *DNSHostProvider) Connected() {
+	hp.mu.Lock()
+	defer hp.mu.Unlock()
+	hp.last = hp.curr
+}