From 3f18d5890e4f8acb7cd3a65579617b55e87951d2 Mon Sep 17 00:00:00 2001
From: Sean Young <sean.young@monax.io>
Date: Fri, 6 Apr 2018 11:19:03 +0100
Subject: [PATCH] Fix locking issues in name cache
Avoid concurrent duplicate calls to backend.GetNameEntry(). This avoids
duplicate work but holds a write lock for the duration.
Ensure we unlock in error path in Sync.
Signed-off-by: Sean Young <sean.young@monax.io>
---
execution/namereg_cache.go | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/execution/namereg_cache.go b/execution/namereg_cache.go
index f941b9f9..5cb0c63a 100644
--- a/execution/namereg_cache.go
+++ b/execution/namereg_cache.go
@@ -109,11 +109,13 @@ func (cache *NameRegCache) Sync(state NameRegWriter) error {
if nameInfo.removed {
err := state.RemoveNameRegEntry(name)
if err != nil {
+ nameInfo.RUnlock()
return err
}
} else if nameInfo.updated {
err := state.UpdateNameRegEntry(nameInfo.entry)
if err != nil {
+ nameInfo.RUnlock()
return err
}
}
@@ -150,16 +152,19 @@ func (cache *NameRegCache) get(name string) (*nameInfo, error) {
nmeInfo := cache.names[name]
cache.RUnlock()
if nmeInfo == nil {
- entry, err := cache.backend.GetNameRegEntry(name)
- if err != nil {
- return nil, err
- }
- nmeInfo = &nameInfo{
- entry: entry,
- }
cache.Lock()
- cache.names[name] = nmeInfo
- cache.Unlock()
+ defer cache.Unlock()
+ nmeInfo = cache.names[name]
+ if nmeInfo == nil {
+ entry, err := cache.backend.GetNameRegEntry(name)
+ if err != nil {
+ return nil, err
+ }
+ nmeInfo = &nameInfo{
+ entry: entry,
+ }
+ cache.names[name] = nmeInfo
+ }
}
return nmeInfo, nil
}
--
GitLab