HBASE-19448 Replace StringBuffer with StringBuilder for hbase-server

Signed-off-by: Chia-Ping Tsai <chia7712@gmail.com>

hbase-server/src/main/java/org/apache/hadoop/hbase/favored/FavoredNodeAssignmentHelper.java

@@ -621,7 +621,7 @@ public class FavoredNodeAssignmentHelper {
   }
 
   public static String getFavoredNodesAsString(List<ServerName> nodes) {
-    StringBuffer strBuf = new StringBuffer();
+    StringBuilder strBuf = new StringBuilder();
     int i = 0;
     for (ServerName node : nodes) {
       strBuf.append(node.getHostAndPort());

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java

@@ -755,7 +755,7 @@ public class BucketCache implements BlockCache, HeapSize {
       freeInProgress = true;
       long bytesToFreeWithoutExtra = 0;
       // Calculate free byte for each bucketSizeinfo
-      StringBuffer msgBuffer = LOG.isDebugEnabled()? new StringBuffer(): null;
+      StringBuilder msgBuffer = LOG.isDebugEnabled()? new StringBuilder(): null;
       BucketAllocator.IndexStatistics[] stats = bucketAllocator.getIndexStatistics();
       long[] bytesToFreeForBucket = new long[stats.length];
       for (int i = 0; i < stats.length; i++) {

hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerFactory.java

@@ -49,7 +49,7 @@ public class RpcServerFactory {
       RpcScheduler scheduler) throws IOException {
     String rpcServerClass = conf.get(CUSTOM_RPC_SERVER_IMPL_CONF_KEY,
         NettyRpcServer.class.getName());
-    StringBuffer servicesList = new StringBuffer();
+    StringBuilder servicesList = new StringBuilder();
     for (BlockingServiceAndInterface s: services) {
       ServiceDescriptor sd = s.getBlockingService().getDescriptorForType();
       if (sd == null) continue; // Can be null for certain tests like TestTokenAuthentication

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/AbstractMemStore.java

@@ -176,7 +176,7 @@ public abstract class AbstractMemStore implements MemStore {
 
   @Override
   public String toString() {
-    StringBuffer buf = new StringBuffer();
+    StringBuilder buf = new StringBuilder();
     int i = 1;
     try {
       for (Segment segment : getSegments()) {

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplit.java

@@ -166,7 +166,7 @@ public class CompactSplit implements CompactionRequester, PropagatingConfigurati
   }
 
   public String dumpQueue() {
-    StringBuffer queueLists = new StringBuffer();
+    StringBuilder queueLists = new StringBuilder();
     queueLists.append("Compaction/Split Queue dump:\n");
     queueLists.append("  LargeCompation Queue:\n");
     BlockingQueue<Runnable> lq = longCompactions.getQueue();

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java

@@ -2266,7 +2266,7 @@ public class HRegion implements HeapSize, PropagatingConfigurationObserver, Regi
   /**
    * Should the memstore be flushed now
    */
-  boolean shouldFlush(final StringBuffer whyFlush) {
+  boolean shouldFlush(final StringBuilder whyFlush) {
     whyFlush.setLength(0);
     // This is a rough measure.
     if (this.maxFlushedSeqId > 0
@@ -8299,7 +8299,7 @@ public class HRegion implements HeapSize, PropagatingConfigurationObserver, Regi
 
   //// method for debugging tests
   void throwException(String title, String regionName) {
-    StringBuffer buf = new StringBuffer();
+    StringBuilder buf = new StringBuilder();
     buf.append(title + ", ");
     buf.append(getRegionInfo().toString());
     buf.append(getRegionInfo().isMetaRegion() ? " meta region " : " ");

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -1753,7 +1753,7 @@ public class HRegionServer extends HasThread implements
 
     @Override
     protected void chore() {
-      final StringBuffer whyFlush = new StringBuffer();
+      final StringBuilder whyFlush = new StringBuilder();
       for (HRegion r : this.server.onlineRegions.values()) {
         if (r == null) continue;
         if (r.shouldFlush(whyFlush)) {

hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSourceManager.java

@@ -835,7 +835,7 @@ public class ReplicationSourceManager implements ReplicationListener {
    * Get a string representation of all the sources' metrics
    */
   public String getStats() {
-    StringBuffer stats = new StringBuffer();
+    StringBuilder stats = new StringBuilder();
     for (ReplicationSourceInterface source : sources) {
       stats.append("Normal source for cluster " + source.getPeerId() + ": ");
       stats.append(source.getStats() + "\n");

hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestMasterOperationsForRegionReplicas.java

@@ -287,7 +287,7 @@ public class TestMasterOperationsForRegionReplicas {
   }
 
   private String printRegions(List<RegionInfo> regions) {
-    StringBuffer strBuf = new StringBuffer();
+    StringBuilder strBuf = new StringBuilder();
     for (RegionInfo r : regions) {
       strBuf.append(" ____ " + r.toString());
     }

hbase-server/src/test/java/org/apache/hadoop/hbase/mob/MobTestUtil.java

@@ -40,7 +40,7 @@ public class MobTestUtil {
   protected static String generateRandomString(int demoLength) {
     String base = "abcdefghijklmnopqrstuvwxyz";
     Random random = new Random();
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     for (int i = 0; i < demoLength; i++) {
       int number = random.nextInt(base.length());
       sb.append(base.charAt(number));

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestDefaultMemStore.java

@@ -928,7 +928,7 @@ public class TestDefaultMemStore {
       p.add(KeyValueTestUtil.create("r", cf, "q", 100, "v"));
       region.put(p);
       edge.setCurrentTimeMillis(1234 + 100);
-      StringBuffer sb = new StringBuffer();
+      StringBuilder sb = new StringBuilder();
       assertTrue(!region.shouldFlush(sb));
       edge.setCurrentTimeMillis(1234 + 10000);
       assertTrue(region.shouldFlush(sb) == expected);
@@ -966,7 +966,7 @@ public class TestDefaultMemStore {
             wFactory.getWAL(hri.getEncodedNameAsBytes(), hri.getTable().getNamespace()));
     addRegionToMETA(meta, r);
     edge.setCurrentTimeMillis(1234 + 100);
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     assertTrue(meta.shouldFlush(sb) == false);
     edge.setCurrentTimeMillis(edge.currentTime() + HRegion.SYSTEM_CACHE_FLUSH_INTERVAL + 1);
     assertTrue(meta.shouldFlush(sb) == true);

hbase-server/src/test/java/org/apache/hadoop/hbase/security/access/SecureTestUtil.java

@@ -85,7 +85,7 @@ public class SecureTestUtil {
     // the superuser list or security won't function properly. We expect the
     // HBase service account(s) to have superuser privilege.
     String currentUser = User.getCurrent().getName();
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     sb.append("admin,");
     sb.append(currentUser);
     // Assumes we won't ever have a minicluster with more than 5 slaves