From f40a43b1a99f488da1400c74482b9c97eaf08515 Mon Sep 17 00:00:00 2001
From: Ondrej Fabry <ofabry@cisco.com>
Date: Fri, 5 Apr 2019 10:18:33 +0200
Subject: [PATCH] Fix WaitReady for VPP client adapters

Change-Id: I57d29a819132d4894691e1131b7d79e19c90456e
Signed-off-by: Ondrej Fabry <ofabry@cisco.com>
---
 adapter/socketclient/socketclient.go | 31 ++++++++++++++++++++++---------
 adapter/vppapiclient/vppapiclient.go | 31 +++++++++++++++++++++----------
 2 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/adapter/socketclient/socketclient.go b/adapter/socketclient/socketclient.go
index f281955..4c576c3 100644
--- a/adapter/socketclient/socketclient.go
+++ b/adapter/socketclient/socketclient.go
@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
-	"github.com/fsnotify/fsnotify"
 	"io"
 	"net"
 	"os"
@@ -13,6 +12,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/fsnotify/fsnotify"
+
 	"github.com/lunixbochs/struc"
 	logger "github.com/sirupsen/logrus"
 
@@ -33,6 +34,10 @@ var (
 	ConnectTimeout    = time.Second * 3
 	DisconnectTimeout = time.Second
 
+	// MaxWaitReady defines maximum duration before waiting for socket file
+	// times out
+	MaxWaitReady = time.Second * 15
+
 	Debug       = os.Getenv("DEBUG_GOVPP_SOCK") != ""
 	DebugMsgIds = os.Getenv("DEBUG_GOVPP_SOCKMSG") != ""
 
@@ -76,7 +81,7 @@ func nilCallback(msgID uint16, data []byte) {
 
 // WaitReady checks socket file existence and waits for it if necessary
 func (c *vppClient) WaitReady() error {
-	// verify file existence
+	// check if file at the path already exists
 	if _, err := os.Stat(c.sockAddr); err == nil {
 		return nil
 	} else if os.IsExist(err) {
@@ -93,17 +98,25 @@ func (c *vppClient) WaitReady() error {
 			Log.Errorf("failed to close file watcher: %v", err)
 		}
 	}()
-	path := filepath.Dir(c.sockAddr)
-	if err := watcher.Add(path); err != nil {
+
+	// start watching directory
+	if err := watcher.Add(filepath.Dir(c.sockAddr)); err != nil {
 		return err
 	}
 
 	for {
-		ev := <-watcher.Events
-		if ev.Name == path {
-			if (ev.Op & fsnotify.Create) == fsnotify.Create {
-				// socket ready
-				return nil
+		select {
+		case <-time.After(MaxWaitReady):
+			return fmt.Errorf("waiting for socket file timed out (%s)", MaxWaitReady)
+		case e := <-watcher.Errors:
+			return e
+		case ev := <-watcher.Events:
+			Log.Debugf("watcher event: %+v", ev)
+			if ev.Name == c.sockAddr {
+				if (ev.Op & fsnotify.Create) == fsnotify.Create {
+					// socket was created, we are ready
+					return nil
+				}
 			}
 		}
 	}
diff --git a/adapter/vppapiclient/vppapiclient.go b/adapter/vppapiclient/vppapiclient.go
index d43c832..037d3ac 100644
--- a/adapter/vppapiclient/vppapiclient.go
+++ b/adapter/vppapiclient/vppapiclient.go
@@ -78,12 +78,19 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"time"
 	"unsafe"
 
 	"git.fd.io/govpp.git/adapter"
 	"github.com/fsnotify/fsnotify"
 )
 
+var (
+	// MaxWaitReady defines maximum duration before waiting for shared memory
+	// segment times out
+	MaxWaitReady = time.Second * 15
+)
+
 const (
 	// shmDir is a directory where shared memory is supposed to be created.
 	shmDir = "/dev/shm/"
@@ -173,16 +180,15 @@ func (a *vppClient) SetMsgCallback(cb adapter.MsgCallback) {
 // WaitReady blocks until shared memory for sending
 // binary api calls is present on the file system.
 func (a *vppClient) WaitReady() error {
-	var path string
-
 	// join the path to the shared memory segment
+	var path string
 	if a.shmPrefix == "" {
 		path = filepath.Join(shmDir, vppShmFile)
 	} else {
 		path = filepath.Join(shmDir, a.shmPrefix+"-"+vppShmFile)
 	}
 
-	// check if file at the path exists
+	// check if file at the path already exists
 	if _, err := os.Stat(path); err == nil {
 		// file exists, we are ready
 		return nil
@@ -197,21 +203,26 @@ func (a *vppClient) WaitReady() error {
 	}
 	defer watcher.Close()
 
+	// start watching directory
 	if err := watcher.Add(shmDir); err != nil {
 		return err
 	}
 
 	for {
-		ev := <-watcher.Events
-		if ev.Name == path {
-			if (ev.Op & fsnotify.Create) == fsnotify.Create {
-				// file was created, we are ready
-				break
+		select {
+		case <-time.After(MaxWaitReady):
+			return fmt.Errorf("waiting for shared memory segment timed out (%s)", MaxWaitReady)
+		case e := <-watcher.Errors:
+			return e
+		case ev := <-watcher.Events:
+			if ev.Name == path {
+				if (ev.Op & fsnotify.Create) == fsnotify.Create {
+					// file was created, we are ready
+					return nil
+				}
 			}
 		}
 	}
-
-	return nil
 }
 
 //export go_msg_callback
-- 
2.16.6