diff --git a/s2core/src/main/scala/org/apache/s2graph/core/utils/SafeUpdateCache.scala b/s2core/src/main/scala/org/apache/s2graph/core/utils/SafeUpdateCache.scala
index bf1f22ce..577ab95a 100644
--- a/s2core/src/main/scala/org/apache/s2graph/core/utils/SafeUpdateCache.scala
+++ b/s2core/src/main/scala/org/apache/s2graph/core/utils/SafeUpdateCache.scala
@@ -6,9 +6,9 @@
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
- * 
+ *
  *   http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
@@ -55,7 +55,9 @@ object SafeUpdateCache {
     Try(BinaryPickle(bytes).unpickle[AnyRef])
   }
 
-  def fromBytes(config: Config, bytes: Array[Byte])(implicit ec: ExecutionContext): SafeUpdateCache = {
+  def fromBytes(config: Config, bytes: Array[Byte])(
+    implicit ec: ExecutionContext
+  ): SafeUpdateCache = {
     import org.apache.hadoop.io.WritableUtils
     val cache: SafeUpdateCache = new SafeUpdateCache(config)
 
@@ -80,23 +82,30 @@ object SafeUpdateCache {
   }
 }
 
-class SafeUpdateCache(val config: Config)
-                     (implicit executionContext: ExecutionContext) {
+class SafeUpdateCache(val config: Config)(
+  implicit executionContext: ExecutionContext
+) {
 
   import java.lang.{Long => JLong}
   import SafeUpdateCache._
 
-
   val maxSize = config.getInt(SafeUpdateCache.MaxSizeKey)
   val systemTtl = config.getInt(SafeUpdateCache.TtlKey)
 
   def this(maxSize: Int, systemTtl: Int)(implicit ec: ExecutionContext) {
-    this(ConfigFactory.parseMap(
-      Map(SafeUpdateCache.MaxSizeKey -> maxSize, SafeUpdateCache.TtlKey -> systemTtl))
+    this(
+      ConfigFactory.parseMap(
+        Map(
+          SafeUpdateCache.MaxSizeKey -> maxSize,
+          SafeUpdateCache.TtlKey -> systemTtl
+        )
+      )
     )
   }
 
-  private val cache = CacheBuilder.newBuilder().maximumSize(maxSize)
+  private val cache = CacheBuilder
+    .newBuilder()
+    .maximumSize(maxSize)
     .build[JLong, (AnyRef, Int, AtomicBoolean)]()
 
   private def toCacheKey(key: String): Long = {
@@ -126,14 +135,19 @@ class SafeUpdateCache(val config: Config)
   def defaultOnEvict(oldValue: AnyRef): Unit = {
     oldValue match {
       case None =>
-      case _ => logger.info(s"[SafeUpdateCache]: ${oldValue.getClass.getName} $oldValue is evicted.")
+      case _ =>
+        logger.info(
+          s"[SafeUpdateCache]: ${oldValue.getClass.getName} $oldValue is evicted."
+        )
     }
   }
 
-  def withCache[T <: AnyRef](key: String,
-                             broadcast: Boolean,
-                             cacheTTLInSecs: Option[Int] = None,
-                             onEvict: AnyRef => Unit = defaultOnEvict)(op: => T): T = {
+  def withCache[T <: AnyRef](
+    key: String,
+    broadcast: Boolean,
+    cacheTTLInSecs: Option[Int] = None,
+    onEvict: AnyRef => Unit = defaultOnEvict
+  )(op: => T): T = {
     val cacheKey = toCacheKey(key)
     val cachedValWithTs = cache.getIfPresent(cacheKey)
 
@@ -155,19 +169,21 @@ class SafeUpdateCache(val config: Config)
 
         if (running) cachedVal
         else {
-          val value = op
-          Future(value)(executionContext) onComplete {
+          Future(op)(executionContext) onComplete {
             case Failure(ex) =>
               put(key, cachedVal, false)
               logger.error(s"withCache update failed: $cacheKey", ex)
             case Success(newValue) =>
-
-              put(key, newValue, broadcast = (broadcast && newValue != cachedVal))
+              put(
+                key,
+                newValue,
+                broadcast = (broadcast && newValue != cachedVal)
+              )
               onEvict(cachedVal)
 
               cachedVal match {
                 case None =>
-                case _ => logger.info(s"withCache update success: $cacheKey")
+                case _    => logger.info(s"withCache update success: $cacheKey")
               }
           }
 
@@ -210,4 +226,3 @@ class SafeUpdateCache(val config: Config)
 
   def shutdown() = {}
 }
-