p2p/simulations/adapters: fix websocket log line parsing in exec adap…

…ter (ethereum#16667)

p2p/simulations/adapters/exec.go

@@ -17,7 +17,6 @@
 package adapters
 
 import (
- "bufio"
  "context"
  "crypto/ecdsa"
  "encoding/json"
@@ -29,7 +28,6 @@ import (
  "os/exec"
  "os/signal"
  "path/filepath"
- "regexp"
  "strings"
  "sync"
  "syscall"
@@ -150,10 +148,6 @@ func (n *ExecNode) Client() (*rpc.Client, error) {
  return n.client, nil
 }
 
-// wsAddrPattern is a regex used to read the WebSocket address from the node's
-// log
-var wsAddrPattern = regexp.MustCompile(`ws://[\d.:]+`)
-
 // Start exec's the node passing the ID and service as command line arguments
 // and the node config encoded as JSON in the _P2P_NODE_CONFIG environment
 // variable
@@ -196,23 +190,9 @@ func (n *ExecNode) Start(snapshots map[string][]byte) (err error) {
  n.Cmd = cmd
 
  // read the WebSocket address from the stderr logs
- var wsAddr string
- wsAddrC := make(chan string)
- go func() {
- s := bufio.NewScanner(stderrR)
- for s.Scan() {
- if strings.Contains(s.Text(), "WebSocket endpoint opened:") {
- wsAddrC <- wsAddrPattern.FindString(s.Text())
- }
- }
- }()
- select {
- case wsAddr = <-wsAddrC:
- if wsAddr == "" {
- return errors.New("failed to read WebSocket address from stderr")
- }
- case <-time.After(10 * time.Second):
- return errors.New("timed out waiting for WebSocket address on stderr")
+ wsAddr, err := findWSAddr(stderrR, 10*time.Second)
+ if err != nil {
+ return fmt.Errorf("error getting WebSocket address: %s", err)
  }
 
  // create the RPC client and load the node info

p2p/simulations/adapters/ws.go

@@ -0,0 +1,51 @@
+package adapters
+
+import (
+ "bufio"
+ "errors"
+ "io"
+ "regexp"
+ "strings"
+ "time"
+)
+
+// wsAddrPattern is a regex used to read the WebSocket address from the node's
+// log
+var wsAddrPattern = regexp.MustCompile(`ws://[\d.:]+`)
+
+func matchWSAddr(str string) (string, bool) {
+ if !strings.Contains(str, "WebSocket endpoint opened") {
+ return "", false
+ }
+
+ return wsAddrPattern.FindString(str), true
+}
+
+// findWSAddr scans through reader r, looking for the log entry with
+// WebSocket address information.
+func findWSAddr(r io.Reader, timeout time.Duration) (string, error) {
+ ch := make(chan string)
+
+ go func() {
+ s := bufio.NewScanner(r)
+ for s.Scan() {
+ addr, ok := matchWSAddr(s.Text())
+ if ok {
+ ch <- addr
+ }
+ }
+ close(ch)
+ }()
+
+ var wsAddr string
+ select {
+ case wsAddr = <-ch:
+ if wsAddr == "" {
+ return "", errors.New("empty result")
+ }
+ case <-time.After(timeout):
+ return "", errors.New("timed out")
+ }
+
+ return wsAddr, nil
+}

p2p/simulations/adapters/ws_test.go

@@ -0,0 +1,21 @@
+package adapters
+
+import (
+ "bytes"
+ "testing"
+ "time"
+)
+
+func TestFindWSAddr(t *testing.T) {
+ line := `t=2018-05-02T19:00:45+0200 lvl=info msg="WebSocket endpoint opened" node.id=26c65a606d1125a44695bc08573190d047152b6b9a776ccbbe593e90f91444d9c1ebdadac6a775ad9fdd0923468a1d698ed3a842c1fb89c1bc0f9d4801f8c39c url=ws://127.0.0.1:59975`
+ buf := bytes.NewBufferString(line)
+ got, err := findWSAddr(buf, 10*time.Second)
+ if err != nil {
+ t.Fatalf("Failed to find addr: %v", err)
+ }
+ expected := `ws://127.0.0.1:59975`
+
+ if got != expected {
+ t.Fatalf("Expected to get '%s', but got '%s'", expected, got)
+ }
+}