Simplified conditions, updated variable to final wherever applicable and removed unreachable throws Exception

src/main/java/org/tikv/cdc/CDCEvent.java

@@ -1,14 +1,13 @@
 package org.tikv.cdc;
 
-import java.util.Objects;
 import org.tikv.kvproto.Cdcpb.Event.Row;
 
 class CDCEvent {
   enum CDCEventType {
     ROW,
     RESOLVED_TS,
-    ERROR;
-  };
+    ERROR
+  }
 
   public final long regionId;
 
@@ -57,7 +56,7 @@ public String toString() {
         builder.append("resolvedTs=").append(resolvedTs);
         break;
       case ROW:
-        builder.append("row=").append(Objects.toString(row));
+        builder.append("row=").append(row);
         break;
     }
     return builder.append("}").toString();

src/main/java/org/tikv/cdc/RegionCDCClient.java

@@ -42,7 +42,7 @@ class RegionCDCClient implements AutoCloseable, StreamObserver<ChangeDataEvent>
 
   private final AtomicBoolean running = new AtomicBoolean(false);
 
-  private boolean started = false;
+  private final boolean started = false;
 
   public RegionCDCClient(
       final TiRegion region,

src/main/java/org/tikv/common/MetricsServer.java

@@ -30,9 +30,8 @@ public class MetricsServer {
   private static MetricsServer METRICS_SERVER_INSTANCE = null;
   private static int metricsServerRefCount = 0;
 
-  private int port;
-  private HTTPServer server;
-  private CollectorRegistry collectorRegistry;
+  private final int port;
+  private final HTTPServer server;
 
   public static MetricsServer getInstance(TiConfiguration conf) {
     if (!conf.isMetricsEnable()) {
@@ -58,16 +57,16 @@ public static MetricsServer getInstance(TiConfiguration conf) {
 
   private MetricsServer(int port) {
     try {
-      this.collectorRegistry = new CollectorRegistry();
-      this.collectorRegistry.register(RawKVClient.RAW_REQUEST_LATENCY);
-      this.collectorRegistry.register(RawKVClient.RAW_REQUEST_FAILURE);
-      this.collectorRegistry.register(RawKVClient.RAW_REQUEST_SUCCESS);
-      this.collectorRegistry.register(RegionStoreClient.GRPC_RAW_REQUEST_LATENCY);
-      this.collectorRegistry.register(RetryPolicy.GRPC_SINGLE_REQUEST_LATENCY);
-      this.collectorRegistry.register(RegionManager.GET_REGION_BY_KEY_REQUEST_LATENCY);
-      this.collectorRegistry.register(PDClient.PD_GET_REGION_BY_KEY_REQUEST_LATENCY);
+      CollectorRegistry collectorRegistry = new CollectorRegistry();
+      collectorRegistry.register(RawKVClient.RAW_REQUEST_LATENCY);
+      collectorRegistry.register(RawKVClient.RAW_REQUEST_FAILURE);
+      collectorRegistry.register(RawKVClient.RAW_REQUEST_SUCCESS);
+      collectorRegistry.register(RegionStoreClient.GRPC_RAW_REQUEST_LATENCY);
+      collectorRegistry.register(RetryPolicy.GRPC_SINGLE_REQUEST_LATENCY);
+      collectorRegistry.register(RegionManager.GET_REGION_BY_KEY_REQUEST_LATENCY);
+      collectorRegistry.register(PDClient.PD_GET_REGION_BY_KEY_REQUEST_LATENCY);
       this.port = port;
-      this.server = new HTTPServer(new InetSocketAddress(port), this.collectorRegistry, true);
+      this.server = new HTTPServer(new InetSocketAddress(port), collectorRegistry, true);
       logger.info("http server is up " + this.server.getPort());
     } catch (Exception e) {
       logger.error("http server not up");

src/main/java/org/tikv/common/PDClient.java

@@ -188,7 +188,7 @@ void waitScatterRegionFinish(Metapb.Region region, BackOffer backOffer) {
                   "wait scatter region %d at key %s is %s",
                   region.getId(),
                   KeyUtils.formatBytes(resp.getDesc().toByteArray()),
-                  resp.getStatus().toString()));
+                  resp.getStatus()));
         }
       }
     }
@@ -422,11 +422,9 @@ public synchronized void updateLeaderOrforwardFollower() {
       logger.info(String.format("can not switch to new leader, try follower forward"));
       List<Pdpb.Member> members = resp.getMembersList();
 
-      boolean hasReachNextMember = false;
       // If we have not used follower forward, try the first follower.
-      if (pdClientWrapper != null && pdClientWrapper.getStoreAddress().equals(leaderUrlStr)) {
-        hasReachNextMember = true;
-      }
+      boolean hasReachNextMember =
+          pdClientWrapper != null && pdClientWrapper.getStoreAddress().equals(leaderUrlStr);
 
       for (int i = 0; i < members.size() * 2; i++) {
         Pdpb.Member member = members.get(i % members.size());

src/main/java/org/tikv/common/TiConfiguration.java

@@ -264,7 +264,7 @@ private static ReplicaRead getReplicaRead(String key) {
   private boolean showRowId = getBoolean(TIKV_SHOW_ROWID);
   private String dbPrefix = get(TIKV_DB_PREFIX);
   private KVMode kvMode = getKvMode(TIKV_KV_MODE);
-  private boolean enableGrpcForward = getBoolean(TIKV_ENABLE_GRPC_FORWARD);
+  private final boolean enableGrpcForward = getBoolean(TIKV_ENABLE_GRPC_FORWARD);
 
   private int kvClientConcurrency = getInt(TIKV_KV_CLIENT_CONCURRENCY);
   private ReplicaRead replicaRead = getReplicaRead(TIKV_REPLICA_READ);
@@ -273,8 +273,8 @@ private static ReplicaRead getReplicaRead(String key) {
 
   private boolean metricsEnable = getBoolean(TIKV_METRICS_ENABLE);
   private int metricsPort = getInt(TIKV_METRICS_PORT);
-  private int grpcHealthCheckTimeout = getInt(TIKV_GRPC_HEALTH_CHECK_TIMEOUT);
-  private int healthCheckPeriodDuration = getInt(TIKV_HEALTH_CHECK_PERIOD_DURATION);
+  private final int grpcHealthCheckTimeout = getInt(TIKV_GRPC_HEALTH_CHECK_TIMEOUT);
+  private final int healthCheckPeriodDuration = getInt(TIKV_HEALTH_CHECK_PERIOD_DURATION);
 
   private final String networkMappingName = get(TIKV_NETWORK_MAPPING_NAME);
   private HostMapping hostMapping = null;

src/main/java/org/tikv/common/TiSession.java

@@ -73,7 +73,7 @@ public class TiSession implements AutoCloseable {
   private volatile ImporterStoreClient.ImporterStoreClientBuilder importerClientBuilder;
   private volatile boolean isClosed = false;
   private volatile SwitchTiKVModeClient switchTiKVModeClient;
-  private MetricsServer metricsServer;
+  private final MetricsServer metricsServer;
   private static final int MAX_SPLIT_REGION_STACK_DEPTH = 6;
 
   public TiSession(TiConfiguration conf) {

src/main/java/org/tikv/common/expression/RangeColumnPartitionPruner.java

@@ -79,7 +79,7 @@ protected Set<Integer> visit(ComparisonBinaryExpression node, LogicalBinaryExpre
     NormalizedPredicate predicate = node.normalize();
     if (predicate == null) {
       throw new UnsupportedOperationException(
-          String.format("ComparisonBinaryExpression %s cannot be normalized", node.toString()));
+          String.format("ComparisonBinaryExpression %s cannot be normalized", node));
     }
     String colRefName = predicate.getColumnRef().getName();
     List<Expression> partExprs = partExprsPerColumnRef.get(colRefName);

src/main/java/org/tikv/common/parser/AstBuilder.java

@@ -117,7 +117,7 @@ public Expression visitDecimalLiteral(MySqlParser.DecimalLiteralContext ctx) {
       return parseIntOrLongOrDec(val);
     }
 
-    throw new UnsupportedSyntaxException(ctx.toString() + ": it is not supported.");
+    throw new UnsupportedSyntaxException(ctx + ": it is not supported.");
   }
 
   @Override
@@ -135,7 +135,7 @@ public Expression visitStringLiteral(MySqlParser.StringLiteralContext ctx) {
       }
       return Constant.create(sb.toString().replace("\"", ""));
     }
-    throw new UnsupportedSyntaxException(ctx.toString() + " is not supported yet");
+    throw new UnsupportedSyntaxException(ctx + " is not supported yet");
   }
 
   @Override
@@ -161,7 +161,7 @@ public Expression visitConstant(MySqlParser.ConstantContext ctx) {
           Doubles.tryParse(ctx.REAL_LITERAL().getSymbol().getText()), RealType.REAL);
     }
 
-    throw new UnsupportedSyntaxException(ctx.toString() + "not supported constant");
+    throw new UnsupportedSyntaxException(ctx + "not supported constant");
   }
 
   @Override
@@ -187,8 +187,7 @@ public Expression visitBinaryComparisonPredicate(
         return ComparisonBinaryExpression.greaterEqual(left, right);
     }
 
-    throw new UnsupportedSyntaxException(
-        ctx.toString() + ": it is not possible reach to this line of code");
+    throw new UnsupportedSyntaxException(ctx + ": it is not possible reach to this line of code");
   }
 
   public Expression visitLogicalExpression(MySqlParser.LogicalExpressionContext ctx) {
@@ -203,8 +202,7 @@ public Expression visitLogicalExpression(MySqlParser.LogicalExpressionContext ct
         return LogicalBinaryExpression.xor(visitChildren(left), visitChildren(right));
     }
 
-    throw new UnsupportedSyntaxException(
-        ctx.toString() + ": it is not possible reach to this line of code");
+    throw new UnsupportedSyntaxException(ctx + ": it is not possible reach to this line of code");
   }
 
   @Override
@@ -222,6 +220,6 @@ public Expression visitMathExpressionAtom(MySqlParser.MathExpressionAtomContext
       case "div":
         return ArithmeticBinaryExpression.divide(left, right);
     }
-    throw new UnsupportedSyntaxException(ctx.toString() + ": it is not supported right now");
+    throw new UnsupportedSyntaxException(ctx + ": it is not supported right now");
   }
 }

src/main/java/org/tikv/common/policy/RetryPolicy.java

@@ -41,9 +41,9 @@ public abstract class RetryPolicy<RespT> {
           .register();
 
   // handles PD and TiKV's error.
-  private ErrorHandler<RespT> handler;
+  private final ErrorHandler<RespT> handler;
 
-  private ImmutableSet<Status.Code> unrecoverableStatus =
+  private final ImmutableSet<Status.Code> unrecoverableStatus =
       ImmutableSet.of(
           Status.Code.ALREADY_EXISTS, Status.Code.PERMISSION_DENIED,
           Status.Code.INVALID_ARGUMENT, Status.Code.NOT_FOUND,

src/main/java/org/tikv/common/region/RegionManager.java

@@ -151,7 +151,7 @@ public Pair<TiRegion, TiStore> getRegionStorePairByKey(
       ByteString key, TiStoreType storeType, BackOffer backOffer) {
     TiRegion region = getRegionByKey(key, backOffer);
     if (!region.isValid()) {
-      throw new TiClientInternalException("Region invalid: " + region.toString());
+      throw new TiClientInternalException("Region invalid: " + region);
     }
 
     TiStore store = null;
@@ -181,7 +181,7 @@ public Pair<TiRegion, TiStore> getRegionStorePairByKey(
 
     if (store == null) {
       throw new TiClientInternalException(
-          "Cannot find valid store on " + storeType + " for region " + region.toString());
+          "Cannot find valid store on " + storeType + " for region " + region);
     }
 
     return Pair.create(region, store);

src/main/java/org/tikv/common/region/StoreHealthyChecker.java

@@ -19,12 +19,12 @@
 public class StoreHealthyChecker implements Runnable {
   private static final Logger logger = LoggerFactory.getLogger(StoreHealthyChecker.class);
   private static final long MAX_CHECK_STORE_TOMBSTONE_TICK = 60;
-  private BlockingQueue<TiStore> taskQueue;
+  private final BlockingQueue<TiStore> taskQueue;
   private final ChannelFactory channelFactory;
   private final ReadOnlyPDClient pdClient;
   private final RegionCache cache;
   private long checkTombstoneTick;
-  private long timeout;
+  private final long timeout;
 
   public StoreHealthyChecker(
       ChannelFactory channelFactory, ReadOnlyPDClient pdClient, RegionCache cache, long timeout) {
@@ -37,11 +37,8 @@ public StoreHealthyChecker(
   }
 
   public boolean scheduleStoreHealthCheck(TiStore store) {
-    if (!this.taskQueue.add(store)) {
-      // add queue false, mark it reachable so that it can be put again.
-      return false;
-    }
-    return true;
+    // add queue false, mark it reachable so that it can be put again.
+    return this.taskQueue.add(store);
   }
 
   private List<TiStore> getValidStores() {
@@ -68,11 +65,7 @@ private boolean checkStoreHealth(TiStore store) {
           HealthGrpc.newBlockingStub(channel).withDeadlineAfter(timeout, TimeUnit.MILLISECONDS);
       HealthCheckRequest req = HealthCheckRequest.newBuilder().build();
       HealthCheckResponse resp = stub.check(req);
-      if (resp.getStatus() == HealthCheckResponse.ServingStatus.SERVING) {
-        return true;
-      } else {
-        return false;
-      }
+      return resp.getStatus() == HealthCheckResponse.ServingStatus.SERVING;
     } catch (Exception e) {
       return false;
     }

src/main/java/org/tikv/common/region/TiStore.java

@@ -6,13 +6,13 @@
 import org.tikv.kvproto.Metapb;
 
 public class TiStore implements Serializable {
-  private static long MAX_FAIL_FORWARD_TIMES = 4;
+  private static final long MAX_FAIL_FORWARD_TIMES = 4;
   private final Metapb.Store store;
   private final Metapb.Store proxyStore;
-  private AtomicBoolean reachable;
-  private AtomicBoolean valid;
-  private AtomicLong failForwardCount;
-  private AtomicBoolean canForward;
+  private final AtomicBoolean reachable;
+  private final AtomicBoolean valid;
+  private final AtomicLong failForwardCount;
+  private final AtomicBoolean canForward;
 
   public TiStore(Metapb.Store store) {
     this.store = store;

src/main/java/org/tikv/common/streaming/StreamingResponse.java

@@ -25,8 +25,8 @@
 import org.tikv.kvproto.Errorpb;
 
 public class StreamingResponse implements Iterable {
-  private Iterator<Coprocessor.Response> resultIterator;
-  private List<Coprocessor.Response> responseList;
+  private final Iterator<Coprocessor.Response> resultIterator;
+  private final List<Coprocessor.Response> responseList;
 
   @SuppressWarnings("unchecked")
   public StreamingResponse(Iterator resultIterator) {

src/main/java/org/tikv/raw/RawKVClient.java

@@ -1097,9 +1097,9 @@ public class TikvIterator implements Iterator<KvPair> {
 
     private Iterator<KvPair> iterator;
 
-    private ByteString startKey;
-    private ByteString endKey;
-    private boolean keyOnly;
+    private final ByteString startKey;
+    private final ByteString endKey;
+    private final boolean keyOnly;
 
     private KvPair last;
 

src/main/java/org/tikv/txn/LockResolverClientV4.java

@@ -244,7 +244,7 @@ private TxnStatus getTxnStatusFromLock(BackOffer bo, Lock lock, long callerStart
         logger.warn(
             String.format(
                 "lock txn not found, lock has expired, CallerStartTs=%d lock str=%s",
-                callerStartTS, lock.toString()));
+                callerStartTS, lock));
         if (lock.getLockType() == Kvrpcpb.Op.PessimisticLock) {
           return new TxnStatus();
         }