From 1bcb1d033f09814bee3b06eaf760b3340628d0af Mon Sep 17 00:00:00 2001
From: Edd Robinson <me@edd.io>
Date: Tue, 2 Feb 2016 19:16:30 +0000
Subject: [PATCH] Allow Close to be called multiple times safely

---
 CHANGELOG.md               |  2 +-
 tsdb/engine/tsm1/engine.go | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 347b872659..6d0d2126e3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,7 +36,7 @@
 - [#5478](https://github.com/influxdata/influxdb/issues/5478): panic: interface conversion: interface is float64, not int64
 - [#5475](https://github.com/influxdata/influxdb/issues/5475): Ensure appropriate exit code returned for non-interactive use of CLI.
 - [#5479](https://github.com/influxdata/influxdb/issues/5479): Bringing up a node as a meta only node causes panic
-- [#5504](https://github.com/influxdata/influxdb/issues/5475): create retention policy on unexistant DB crash InfluxDB
+- [#5504](https://github.com/influxdata/influxdb/issues/5504): create retention policy on unexistant DB crash InfluxDB
 - [#5505](https://github.com/influxdata/influxdb/issues/5505): Clear authCache in meta.Client when password changes.
 - [#5244](https://github.com/influxdata/influxdb/issues/5244): panic: ensure it's safe to close engine multiple times.
 
diff --git a/tsdb/engine/tsm1/engine.go b/tsdb/engine/tsm1/engine.go
index 77d0c1a62e..3e174a2a07 100644
--- a/tsdb/engine/tsm1/engine.go
+++ b/tsdb/engine/tsm1/engine.go
@@ -141,8 +141,15 @@ func (e *Engine) Open() error {
 	return nil
 }
 
-// Close closes the engine.
+// Close closes the engine. Subsequent calls to Close are a nop.
 func (e *Engine) Close() error {
+	e.mu.RLock()
+	if e.done == nil {
+		e.mu.RUnlock()
+		return nil
+	}
+	e.mu.RUnlock()
+
 	// Shutdown goroutines and wait.
 	close(e.done)
 	e.wg.Wait()
@@ -150,6 +157,7 @@ func (e *Engine) Close() error {
 	// Lock now and close everything else down.
 	e.mu.Lock()
 	defer e.mu.Unlock()
+	e.done = nil // Ensures that the channel will not be closed again.
 
 	if err := e.FileStore.Close(); err != nil {
 		return err