5 files changed, 46 insertions, 6 deletions
diff --git a/go/util/concurrent_read_map.go b/go/util/concurrent_read_map.go
new file mode 100644
index 000000000..880fe54e3
--- /dev/null
+++ b/go/util/concurrent_read_map.go
@@ -0,0 +1,39 @@
+package util
+
+import (
+	"sync"
+)
+
+// A mostly for read map, which can thread-safely
+// initialize the map entries.
+type ConcurrentReadMap struct {
+	rmutex sync.RWMutex
+	mutex  sync.Mutex
+	Items  map[string]interface{}
+}
+
+func NewConcurrentReadMap() *ConcurrentReadMap {
+	return &ConcurrentReadMap{Items: make(map[string]interface{})}
+}
+
+func (m *ConcurrentReadMap) initMapEntry(key string, newEntry func() interface{}) (value interface{}) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	if value, ok := m.Items[key]; ok {
+		return value
+	}
+	value = newEntry()
+	m.Items[key] = value
+	return value
+}
+
+func (m *ConcurrentReadMap) Get(key string, newEntry func() interface{}) interface{} {
+	m.rmutex.RLock()
+	if value, ok := m.Items[key]; ok {
+		m.rmutex.RUnlock()
+		return value
+	} else {
+		m.rmutex.RUnlock()
+		return m.initMapEntry(key, newEntry)
+	}
+}
diff --git a/go/util/config.go b/go/util/config.go
index 050fd0e64..4cf1d7c64 100644
--- a/go/util/config.go
+++ b/go/util/config.go
@@ -10,9 +10,10 @@ package util
 
 import (
 	"bytes"
-	"github.com/chrislusf/weed-fs/go/glog"
 	"encoding/json"
 	"os"
+
+	"github.com/chrislusf/weed-fs/go/glog"
 )
 
 type Config struct {
diff --git a/go/util/constants.go b/go/util/constants.go
index db1ca38e5..d677ba44f 100644
--- a/go/util/constants.go
+++ b/go/util/constants.go
@@ -1,7 +1,5 @@
 package util
 
-import ()
-
 const (
-	VERSION = "0.64"
+	VERSION = "0.67"
 )
diff --git a/go/util/file_util.go b/go/util/file_util.go
index 412d98458..30e24f001 100644
--- a/go/util/file_util.go
+++ b/go/util/file_util.go
@@ -2,9 +2,10 @@ package util
 
 import (
 	"bufio"
-	"github.com/chrislusf/weed-fs/go/glog"
 	"errors"
 	"os"
+
+	"github.com/chrislusf/weed-fs/go/glog"
 )
 
 func TestFolderWritable(folder string) (err error) {
diff --git a/go/util/net_timeout.go b/go/util/net_timeout.go
index eb80822b5..f274e4802 100644
--- a/go/util/net_timeout.go
+++ b/go/util/net_timeout.go
@@ -1,9 +1,10 @@
 package util
 
 import (
-	"github.com/chrislusf/weed-fs/go/stats"
 	"net"
 	"time"
+
+	"github.com/chrislusf/weed-fs/go/stats"
 )
 
 // Listener wraps a net.Listener, and gives a place to store the timeout