From f605e1138dd798625b78c66c37880b64fa89b2e3 Mon Sep 17 00:00:00 2001
From: Barak Michener <me@barakmich.com>
Date: Sat, 16 Aug 2014 16:52:09 -0400
Subject: [PATCH 1/2] kortschak's fix

---
 query/gremlin/session.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/query/gremlin/session.go b/query/gremlin/session.go
index 8000c17..c178785 100644
--- a/query/gremlin/session.go
+++ b/query/gremlin/session.go
@@ -111,7 +111,6 @@ func (s *Session) SendResult(r *Result) bool {
 }
 
 func (s *Session) runUnsafe(input interface{}) (otto.Value, error) {
-	s.kill = make(chan struct{})
 	defer func() {
 		if r := recover(); r != nil {
 			if r == ErrKillTimeout {
@@ -125,9 +124,12 @@ func (s *Session) runUnsafe(input interface{}) (otto.Value, error) {
 	// Use buffered chan to prevent blocking.
 	s.env.Interrupt = make(chan func(), 1)
 
+	ready := make(chan struct{})
+	s.kill = make(chan struct{})
 	if s.timeout >= 0 {
 		go func() {
 			time.Sleep(s.timeout)
+			<-ready
 			close(s.kill)
 			s.envLock.Lock()
 			defer s.envLock.Unlock()
@@ -143,6 +145,7 @@ func (s *Session) runUnsafe(input interface{}) (otto.Value, error) {
 	s.envLock.Lock()
 	env := s.env
 	s.envLock.Unlock()
+	close(ready)
 	return env.Run(input)
 }
 

From c1ff6ce1aa584a6354fe29793230d3b9556526c8 Mon Sep 17 00:00:00 2001
From: Barak Michener <me@barakmich.com>
Date: Sat, 16 Aug 2014 18:03:05 -0400
Subject: [PATCH 2/2] lock s.kill, send done signal

---
 query/gremlin/session.go | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/query/gremlin/session.go b/query/gremlin/session.go
index c178785..afd77b6 100644
--- a/query/gremlin/session.go
+++ b/query/gremlin/session.go
@@ -93,8 +93,11 @@ func (s *Session) SendResult(r *Result) bool {
 	if s.limit >= 0 && s.limit == s.count {
 		return false
 	}
+	s.envLock.Lock()
+	kill := s.kill
+	s.envLock.Unlock()
 	select {
-	case <-s.kill:
+	case <-kill:
 		return false
 	default:
 	}
@@ -125,28 +128,40 @@ func (s *Session) runUnsafe(input interface{}) (otto.Value, error) {
 	s.env.Interrupt = make(chan func(), 1)
 
 	ready := make(chan struct{})
-	s.kill = make(chan struct{})
+	done := make(chan struct{})
 	if s.timeout >= 0 {
 		go func() {
 			time.Sleep(s.timeout)
 			<-ready
-			close(s.kill)
-			s.envLock.Lock()
-			defer s.envLock.Unlock()
-			if s.env != nil {
-				s.env.Interrupt <- func() {
-					panic(ErrKillTimeout)
+			select {
+			case <-done:
+				return
+			default:
+				close(s.kill)
+				s.envLock.Lock()
+				defer s.envLock.Unlock()
+				s.kill = nil
+				if s.env != nil {
+					s.env.Interrupt <- func() {
+						panic(ErrKillTimeout)
+					}
+					s.env = s.emptyEnv
 				}
-				s.env = s.emptyEnv
+				return
 			}
 		}()
 	}
 
 	s.envLock.Lock()
 	env := s.env
+	if s.kill == nil {
+		s.kill = make(chan struct{})
+	}
 	s.envLock.Unlock()
 	close(ready)
-	return env.Run(input)
+	out, err := env.Run(input)
+	close(done)
+	return out, err
 }
 
 func (s *Session) ExecInput(input string, out chan interface{}, limit int) {
@@ -257,8 +272,11 @@ func (s *Session) GetJson() ([]interface{}, error) {
 	if s.err != nil {
 		return nil, s.err
 	}
+	s.envLock.Lock()
+	kill := s.kill
+	s.envLock.Unlock()
 	select {
-	case <-s.kill:
+	case <-kill:
 		return nil, ErrKillTimeout
 	default:
 		return s.dataOutput, nil