socketclient: wait for socket to be created

domain sockets are checked/watched for existence in same
manner as shm prefixes
also the connection attempts and timeout in between can
be configured for async-connect

Change-Id: I084a3efaefea10d106866968deab90d3fda77cfe
Signed-off-by: Vladimir Lavor <vlavor@cisco.com>

1 files changed, 26 insertions, 11 deletions

diff --git a/core/connection.go b/core/connection.go
index a21cc28..67c7e1d 100644
--- a/core/connection.go
+++ b/core/connection.go
@@ -29,6 +29,11 @@ import (
 	"git.fd.io/govpp.git/codec"
 )
 
+const (
+	DefaultReconnectInterval    = time.Second // default interval between reconnect attempts
+	DefaultMaxReconnectAttempts = 3           // default maximum number of reconnect attempts
+)
+
 var (
 	RequestChanBufSize      = 100 // default size of the request channel buffer
 	ReplyChanBufSize        = 100 // default size of the reply channel buffer
@@ -36,12 +41,10 @@ var (
 )
 
 var (
-	HealthCheckProbeInterval = time.Second * 1        // default health check probe interval
+	HealthCheckProbeInterval = time.Second            // default health check probe interval
 	HealthCheckReplyTimeout  = time.Millisecond * 100 // timeout for reply to a health check probe
 	HealthCheckThreshold     = 1                      // number of failed health checks until the error is reported
-	DefaultReplyTimeout      = time.Second * 1        // default timeout for replies from VPP
-	ReconnectInterval        = time.Second * 1        // default interval for reconnect attempts
-	MaxReconnectAttempts     = 3                      // maximum number of reconnect attempts
+	DefaultReplyTimeout      = time.Second            // default timeout for replies from VPP
 )
 
 // ConnectionState represents the current state of the connection to VPP.
@@ -88,6 +91,9 @@ type Connection struct {
 	vppClient adapter.VppAPI // VPP binary API client
 	//statsClient adapter.StatsAPI // VPP stats API client
 
+	maxAttempts int           // interval for reconnect attempts
+	recInterval time.Duration // maximum number of reconnect attempts
+
 	vppConnected uint32 // non-zero if the adapter is connected to VPP
 
 	codec  *codec.MsgCodec        // message codec
@@ -108,9 +114,18 @@ type Connection struct {
 	lastReply     time.Time  // time of the last received reply from VPP
 }
 
-func newConnection(binapi adapter.VppAPI) *Connection {
+func newConnection(binapi adapter.VppAPI, attempts int, interval time.Duration) *Connection {
+	if attempts == 0 {
+		attempts = DefaultMaxReconnectAttempts
+	}
+	if interval == 0 {
+		interval = DefaultReconnectInterval
+	}
+
 	c := &Connection{
 		vppClient:     binapi,
+		maxAttempts:   attempts,
+		recInterval:   interval,
 		codec:         &codec.MsgCodec{},
 		msgIDs:        make(map[string]uint16),
 		msgMap:        make(map[uint16]api.Message),
@@ -126,7 +141,7 @@ func newConnection(binapi adapter.VppAPI) *Connection {
 // Only one connection attempt will be performed.
 func Connect(binapi adapter.VppAPI) (*Connection, error) {
 	// create new connection handle
-	c := newConnection(binapi)
+	c := newConnection(binapi, DefaultMaxReconnectAttempts, DefaultReconnectInterval)
 
 	// blocking attempt to connect to VPP
 	if err := c.connectVPP(); err != nil {
@@ -140,9 +155,9 @@ func Connect(binapi adapter.VppAPI) (*Connection, error) {
 // and ConnectionState channel. This call does not block until connection is established, it
 // returns immediately. The caller is supposed to watch the returned ConnectionState channel for
 // Connected/Disconnected events. In case of disconnect, the library will asynchronously try to reconnect.
-func AsyncConnect(binapi adapter.VppAPI) (*Connection, chan ConnectionEvent, error) {
+func AsyncConnect(binapi adapter.VppAPI, attempts int, interval time.Duration) (*Connection, chan ConnectionEvent, error) {
 	// create new connection handle
-	c := newConnection(binapi)
+	c := newConnection(binapi, attempts, interval)
 
 	// asynchronously attempt to connect to VPP
 	connChan := make(chan ConnectionEvent, NotificationChanBufSize)
@@ -247,10 +262,10 @@ func (c *Connection) connectLoop(connChan chan ConnectionEvent) {
 			// signal connected event
 			connChan <- ConnectionEvent{Timestamp: time.Now(), State: Connected}
 			break
-		} else if reconnectAttempts < MaxReconnectAttempts {
+		} else if reconnectAttempts < c.maxAttempts {
 			reconnectAttempts++
-			log.Errorf("connecting failed (attempt %d/%d): %v", reconnectAttempts, MaxReconnectAttempts, err)
-			time.Sleep(ReconnectInterval)
+			log.Errorf("connecting failed (attempt %d/%d): %v", reconnectAttempts, c.maxAttempts, err)
+			time.Sleep(c.recInterval)
 		} else {
 			connChan <- ConnectionEvent{Timestamp: time.Now(), State: Failed, Error: err}
 			return