HugeGraph-407: add KeyLock class

Change-Id: I655bdf4da20e0c6b6d7796958485ab066f0020f1

src/main/java/com/baidu/hugegraph/concurrent/KeyLock.java

@@ -0,0 +1,26 @@
+package com.baidu.hugegraph.concurrent;
+
+import java.util.concurrent.locks.Lock;
+
+import com.google.common.util.concurrent.Striped;
+
+public class KeyLock {
+
+    private Striped<Lock> locks;
+
+    public KeyLock() {
+        this(Runtime.getRuntime().availableProcessors() * 4);
+    }
+
+    public KeyLock(int size) {
+        this.locks = Striped.lock(size);
+    }
+
+    public final void lock(Object key) {
+        this.locks.get(key).lock();
+    }
+
+    public final void unlock(Object key) {
+        this.locks.get(key).unlock();
+    }
+}