diff --git a/src/main/java/org/tikv/AbstractGRPCClient.java b/src/main/java/org/tikv/common/AbstractGRPCClient.java
similarity index 95%
rename from src/main/java/org/tikv/AbstractGRPCClient.java
rename to src/main/java/org/tikv/common/AbstractGRPCClient.java
index c352b8b4ed..ee7e0fca7b 100644
--- a/src/main/java/org/tikv/AbstractGRPCClient.java
+++ b/src/main/java/org/tikv/common/AbstractGRPCClient.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import static io.grpc.stub.ClientCalls.asyncBidiStreamingCall;
 import static io.grpc.stub.ClientCalls.blockingServerStreamingCall;
@@ -24,11 +24,11 @@ import io.grpc.stub.ClientCalls;
 import io.grpc.stub.StreamObserver;
 import java.util.function.Supplier;
 import org.apache.log4j.Logger;
-import org.tikv.operation.ErrorHandler;
-import org.tikv.policy.RetryMaxMs.Builder;
-import org.tikv.policy.RetryPolicy;
-import org.tikv.streaming.StreamingResponse;
-import org.tikv.util.BackOffer;
+import org.tikv.common.operation.ErrorHandler;
+import org.tikv.common.policy.RetryMaxMs.Builder;
+import org.tikv.common.policy.RetryPolicy;
+import org.tikv.common.streaming.StreamingResponse;
+import org.tikv.common.util.BackOffer;
 
 public abstract class AbstractGRPCClient<
         BlockingStubT extends AbstractStub<BlockingStubT>, StubT extends AbstractStub<StubT>>
diff --git a/src/main/java/org/tikv/PDClient.java b/src/main/java/org/tikv/common/PDClient.java
similarity index 93%
rename from src/main/java/org/tikv/PDClient.java
rename to src/main/java/org/tikv/common/PDClient.java
index 405f6fd7d5..39ec067bb6 100644
--- a/src/main/java/org/tikv/PDClient.java
+++ b/src/main/java/org/tikv/common/PDClient.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -30,30 +30,20 @@ import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
-import org.tikv.codec.Codec.BytesCodec;
-import org.tikv.codec.CodecDataOutput;
-import org.tikv.exception.GrpcException;
-import org.tikv.exception.TiClientInternalException;
+import org.tikv.common.codec.Codec.BytesCodec;
+import org.tikv.common.codec.CodecDataOutput;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.meta.TiTimestamp;
+import org.tikv.common.operation.PDErrorHandler;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.FutureObserver;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.PDGrpc;
 import org.tikv.kvproto.PDGrpc.PDBlockingStub;
 import org.tikv.kvproto.PDGrpc.PDStub;
-import org.tikv.kvproto.Pdpb.GetMembersRequest;
-import org.tikv.kvproto.Pdpb.GetMembersResponse;
-import org.tikv.kvproto.Pdpb.GetRegionByIDRequest;
-import org.tikv.kvproto.Pdpb.GetRegionRequest;
-import org.tikv.kvproto.Pdpb.GetRegionResponse;
-import org.tikv.kvproto.Pdpb.GetStoreRequest;
-import org.tikv.kvproto.Pdpb.GetStoreResponse;
-import org.tikv.kvproto.Pdpb.RequestHeader;
-import org.tikv.kvproto.Pdpb.Timestamp;
-import org.tikv.kvproto.Pdpb.TsoRequest;
-import org.tikv.kvproto.Pdpb.TsoResponse;
-import org.tikv.meta.TiTimestamp;
-import org.tikv.operation.PDErrorHandler;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.FutureObserver;
+import org.tikv.kvproto.Pdpb.*;
 
 public class PDClient extends AbstractGRPCClient<PDBlockingStub, PDStub>
     implements ReadOnlyPDClient {
diff --git a/src/main/java/org/tikv/ReadOnlyPDClient.java b/src/main/java/org/tikv/common/ReadOnlyPDClient.java
similarity index 92%
rename from src/main/java/org/tikv/ReadOnlyPDClient.java
rename to src/main/java/org/tikv/common/ReadOnlyPDClient.java
index 1c4cae9946..225b0112f6 100644
--- a/src/main/java/org/tikv/ReadOnlyPDClient.java
+++ b/src/main/java/org/tikv/common/ReadOnlyPDClient.java
@@ -13,14 +13,14 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import com.google.protobuf.ByteString;
 import java.util.concurrent.Future;
+import org.tikv.common.meta.TiTimestamp;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
 import org.tikv.kvproto.Metapb.Store;
-import org.tikv.meta.TiTimestamp;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
 
 /** Readonly PD client including only reading related interface Supposed for TiDB-like use cases */
 public interface ReadOnlyPDClient {
diff --git a/src/main/java/org/tikv/Snapshot.java b/src/main/java/org/tikv/common/Snapshot.java
similarity index 86%
rename from src/main/java/org/tikv/Snapshot.java
rename to src/main/java/org/tikv/common/Snapshot.java
index cafe0a819d..666ca9bb7f 100644
--- a/src/main/java/org/tikv/Snapshot.java
+++ b/src/main/java/org/tikv/common/Snapshot.java
@@ -13,26 +13,26 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
-import static org.tikv.util.KeyRangeUtils.makeRange;
+import static org.tikv.common.util.KeyRangeUtils.makeRange;
 
 import com.google.common.collect.Range;
 import com.google.protobuf.ByteString;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
-import org.tikv.exception.TiClientInternalException;
-import org.tikv.key.Key;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.key.Key;
+import org.tikv.common.meta.TiTimestamp;
+import org.tikv.common.operation.iterator.ConcreteScanIterator;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Kvrpcpb.KvPair;
 import org.tikv.kvproto.Metapb.Store;
-import org.tikv.meta.TiTimestamp;
-import org.tikv.operation.iterator.ConcreteScanIterator;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class Snapshot {
   private final TiTimestamp timestamp;
diff --git a/src/main/java/org/tikv/TiConfiguration.java b/src/main/java/org/tikv/common/TiConfiguration.java
similarity index 99%
rename from src/main/java/org/tikv/TiConfiguration.java
rename to src/main/java/org/tikv/common/TiConfiguration.java
index 059e22924e..eecbc10c17 100644
--- a/src/main/java/org/tikv/TiConfiguration.java
+++ b/src/main/java/org/tikv/common/TiConfiguration.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.net.HostAndPort;
diff --git a/src/main/java/org/tikv/TiSession.java b/src/main/java/org/tikv/common/TiSession.java
similarity index 97%
rename from src/main/java/org/tikv/TiSession.java
rename to src/main/java/org/tikv/common/TiSession.java
index 8110616f97..8cea60fece 100644
--- a/src/main/java/org/tikv/TiSession.java
+++ b/src/main/java/org/tikv/common/TiSession.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import com.google.common.net.HostAndPort;
 import io.grpc.ManagedChannel;
@@ -21,7 +21,7 @@ import io.grpc.ManagedChannelBuilder;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
-import org.tikv.region.RegionManager;
+import org.tikv.common.region.RegionManager;
 
 public class TiSession implements AutoCloseable {
   private static final Map<String, ManagedChannel> connPool = new HashMap<>();
diff --git a/src/main/java/org/tikv/codec/Codec.java b/src/main/java/org/tikv/common/codec/Codec.java
similarity index 99%
rename from src/main/java/org/tikv/codec/Codec.java
rename to src/main/java/org/tikv/common/codec/Codec.java
index 8bd473b7e2..76fc5ae59e 100644
--- a/src/main/java/org/tikv/codec/Codec.java
+++ b/src/main/java/org/tikv/common/codec/Codec.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
@@ -22,7 +22,7 @@ import java.math.BigDecimal;
 import java.sql.Date;
 import java.util.Arrays;
 import org.joda.time.*;
-import org.tikv.exception.InvalidCodecFormatException;
+import org.tikv.common.exception.InvalidCodecFormatException;
 
 public class Codec {
 
diff --git a/src/main/java/org/tikv/codec/CodecDataInput.java b/src/main/java/org/tikv/common/codec/CodecDataInput.java
similarity index 99%
rename from src/main/java/org/tikv/codec/CodecDataInput.java
rename to src/main/java/org/tikv/common/codec/CodecDataInput.java
index f1daa95c16..1705819346 100644
--- a/src/main/java/org/tikv/codec/CodecDataInput.java
+++ b/src/main/java/org/tikv/common/codec/CodecDataInput.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import com.google.protobuf.ByteString;
 import java.io.*;
diff --git a/src/main/java/org/tikv/codec/CodecDataOutput.java b/src/main/java/org/tikv/common/codec/CodecDataOutput.java
similarity index 99%
rename from src/main/java/org/tikv/codec/CodecDataOutput.java
rename to src/main/java/org/tikv/common/codec/CodecDataOutput.java
index 984bdb1650..1af5fe3fe9 100644
--- a/src/main/java/org/tikv/codec/CodecDataOutput.java
+++ b/src/main/java/org/tikv/common/codec/CodecDataOutput.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import com.google.protobuf.ByteString;
 import java.io.ByteArrayOutputStream;
diff --git a/src/main/java/org/tikv/codec/KeyUtils.java b/src/main/java/org/tikv/common/codec/KeyUtils.java
similarity index 98%
rename from src/main/java/org/tikv/codec/KeyUtils.java
rename to src/main/java/org/tikv/common/codec/KeyUtils.java
index 8677cd604a..8d79dc6cc8 100644
--- a/src/main/java/org/tikv/codec/KeyUtils.java
+++ b/src/main/java/org/tikv/common/codec/KeyUtils.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import com.google.common.primitives.UnsignedBytes;
 import com.google.protobuf.ByteString;
diff --git a/src/main/java/org/tikv/codec/MyDecimal.java b/src/main/java/org/tikv/common/codec/MyDecimal.java
similarity index 99%
rename from src/main/java/org/tikv/codec/MyDecimal.java
rename to src/main/java/org/tikv/common/codec/MyDecimal.java
index 3c339600a2..a1aa298ad2 100644
--- a/src/main/java/org/tikv/codec/MyDecimal.java
+++ b/src/main/java/org/tikv/common/codec/MyDecimal.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import com.google.common.annotations.VisibleForTesting;
 import java.math.BigDecimal;
diff --git a/src/main/java/org/tikv/exception/GrpcException.java b/src/main/java/org/tikv/common/exception/GrpcException.java
similarity index 95%
rename from src/main/java/org/tikv/exception/GrpcException.java
rename to src/main/java/org/tikv/common/exception/GrpcException.java
index e4011d8757..8be3366e57 100644
--- a/src/main/java/org/tikv/exception/GrpcException.java
+++ b/src/main/java/org/tikv/common/exception/GrpcException.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.exception;
+package org.tikv.common.exception;
 
 public class GrpcException extends RuntimeException {
   public GrpcException(Exception e) {
diff --git a/src/main/java/org/tikv/exception/InvalidCodecFormatException.java b/src/main/java/org/tikv/common/exception/InvalidCodecFormatException.java
similarity index 95%
rename from src/main/java/org/tikv/exception/InvalidCodecFormatException.java
rename to src/main/java/org/tikv/common/exception/InvalidCodecFormatException.java
index b9d030783a..4cb6cf210a 100644
--- a/src/main/java/org/tikv/exception/InvalidCodecFormatException.java
+++ b/src/main/java/org/tikv/common/exception/InvalidCodecFormatException.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.exception;
+package org.tikv.common.exception;
 
 public class InvalidCodecFormatException extends RuntimeException {
   public InvalidCodecFormatException(String msg) {
diff --git a/src/main/java/org/tikv/exception/KeyException.java b/src/main/java/org/tikv/common/exception/KeyException.java
similarity index 96%
rename from src/main/java/org/tikv/exception/KeyException.java
rename to src/main/java/org/tikv/common/exception/KeyException.java
index b2c4130b21..56a7268ebb 100644
--- a/src/main/java/org/tikv/exception/KeyException.java
+++ b/src/main/java/org/tikv/common/exception/KeyException.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.exception;
+package org.tikv.common.exception;
 
 import org.tikv.kvproto.Kvrpcpb;
 
diff --git a/src/main/java/org/tikv/exception/RegionException.java b/src/main/java/org/tikv/common/exception/RegionException.java
similarity index 95%
rename from src/main/java/org/tikv/exception/RegionException.java
rename to src/main/java/org/tikv/common/exception/RegionException.java
index 18a7289af1..14b0709b91 100644
--- a/src/main/java/org/tikv/exception/RegionException.java
+++ b/src/main/java/org/tikv/common/exception/RegionException.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.exception;
+package org.tikv.common.exception;
 
 import org.tikv.kvproto.Errorpb.Error;
 
diff --git a/src/main/java/org/tikv/exception/TiClientInternalException.java b/src/main/java/org/tikv/common/exception/TiClientInternalException.java
similarity index 95%
rename from src/main/java/org/tikv/exception/TiClientInternalException.java
rename to src/main/java/org/tikv/common/exception/TiClientInternalException.java
index ba89548135..a1098df549 100644
--- a/src/main/java/org/tikv/exception/TiClientInternalException.java
+++ b/src/main/java/org/tikv/common/exception/TiClientInternalException.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.exception;
+package org.tikv.common.exception;
 
 public class TiClientInternalException extends RuntimeException {
   public TiClientInternalException(String msg) {
diff --git a/src/main/java/org/tikv/key/Key.java b/src/main/java/org/tikv/common/key/Key.java
similarity index 96%
rename from src/main/java/org/tikv/key/Key.java
rename to src/main/java/org/tikv/common/key/Key.java
index 678ca42b54..4c1697b214 100644
--- a/src/main/java/org/tikv/key/Key.java
+++ b/src/main/java/org/tikv/common/key/Key.java
@@ -13,14 +13,14 @@
  * limitations under the License.
  */
 
-package org.tikv.key;
+package org.tikv.common.key;
 
 import static java.util.Objects.requireNonNull;
-import static org.tikv.codec.KeyUtils.formatBytes;
+import static org.tikv.common.codec.KeyUtils.formatBytes;
 
 import com.google.protobuf.ByteString;
 import java.util.Arrays;
-import org.tikv.util.FastByteComparisons;
+import org.tikv.common.util.FastByteComparisons;
 
 public class Key implements Comparable<Key> {
 
diff --git a/src/main/java/org/tikv/meta/TiTimestamp.java b/src/main/java/org/tikv/common/meta/TiTimestamp.java
similarity index 97%
rename from src/main/java/org/tikv/meta/TiTimestamp.java
rename to src/main/java/org/tikv/common/meta/TiTimestamp.java
index ed9c521a56..ce91214f6b 100644
--- a/src/main/java/org/tikv/meta/TiTimestamp.java
+++ b/src/main/java/org/tikv/common/meta/TiTimestamp.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.meta;
+package org.tikv.common.meta;
 
 import java.io.Serializable;
 
diff --git a/src/main/java/org/tikv/operation/ErrorHandler.java b/src/main/java/org/tikv/common/operation/ErrorHandler.java
similarity index 94%
rename from src/main/java/org/tikv/operation/ErrorHandler.java
rename to src/main/java/org/tikv/common/operation/ErrorHandler.java
index 49a9d15bdf..48e964a2b7 100644
--- a/src/main/java/org/tikv/operation/ErrorHandler.java
+++ b/src/main/java/org/tikv/common/operation/ErrorHandler.java
@@ -15,9 +15,9 @@
  *
  */
 
-package org.tikv.operation;
+package org.tikv.common.operation;
 
-import org.tikv.util.BackOffer;
+import org.tikv.common.util.BackOffer;
 
 public interface ErrorHandler<RespT> {
   /**
diff --git a/src/main/java/org/tikv/operation/KVErrorHandler.java b/src/main/java/org/tikv/common/operation/KVErrorHandler.java
similarity index 95%
rename from src/main/java/org/tikv/operation/KVErrorHandler.java
rename to src/main/java/org/tikv/common/operation/KVErrorHandler.java
index ad5e8cbe4a..922820c261 100644
--- a/src/main/java/org/tikv/operation/KVErrorHandler.java
+++ b/src/main/java/org/tikv/common/operation/KVErrorHandler.java
@@ -15,21 +15,21 @@
  *
  */
 
-package org.tikv.operation;
+package org.tikv.common.operation;
 
 import com.google.protobuf.ByteString;
 import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import java.util.function.Function;
 import org.apache.log4j.Logger;
-import org.tikv.codec.KeyUtils;
-import org.tikv.exception.GrpcException;
+import org.tikv.common.codec.KeyUtils;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.region.RegionErrorReceiver;
+import org.tikv.common.region.RegionManager;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffFunction;
+import org.tikv.common.util.BackOffer;
 import org.tikv.kvproto.Errorpb;
-import org.tikv.region.RegionErrorReceiver;
-import org.tikv.region.RegionManager;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffFunction;
-import org.tikv.util.BackOffer;
 
 // TODO: consider refactor to Builder mode
 public class KVErrorHandler<RespT> implements ErrorHandler<RespT> {
diff --git a/src/main/java/org/tikv/operation/PDErrorHandler.java b/src/main/java/org/tikv/common/operation/PDErrorHandler.java
similarity index 89%
rename from src/main/java/org/tikv/operation/PDErrorHandler.java
rename to src/main/java/org/tikv/common/operation/PDErrorHandler.java
index 03690a80da..2f8054bec0 100644
--- a/src/main/java/org/tikv/operation/PDErrorHandler.java
+++ b/src/main/java/org/tikv/common/operation/PDErrorHandler.java
@@ -15,15 +15,15 @@
  *
  */
 
-package org.tikv.operation;
+package org.tikv.common.operation;
 
 import java.util.function.Function;
 import org.apache.log4j.Logger;
-import org.tikv.PDClient;
-import org.tikv.exception.GrpcException;
+import org.tikv.common.PDClient;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.util.BackOffFunction;
+import org.tikv.common.util.BackOffer;
 import org.tikv.kvproto.Pdpb;
-import org.tikv.util.BackOffFunction;
-import org.tikv.util.BackOffer;
 
 public class PDErrorHandler<RespT> implements ErrorHandler<RespT> {
   private static final Logger logger = Logger.getLogger(PDErrorHandler.class);
diff --git a/src/main/java/org/tikv/operation/iterator/ConcreteScanIterator.java b/src/main/java/org/tikv/common/operation/iterator/ConcreteScanIterator.java
similarity index 83%
rename from src/main/java/org/tikv/operation/iterator/ConcreteScanIterator.java
rename to src/main/java/org/tikv/common/operation/iterator/ConcreteScanIterator.java
index 6966faa26c..d430b26324 100644
--- a/src/main/java/org/tikv/operation/iterator/ConcreteScanIterator.java
+++ b/src/main/java/org/tikv/common/operation/iterator/ConcreteScanIterator.java
@@ -13,16 +13,16 @@
  * limitations under the License.
  */
 
-package org.tikv.operation.iterator;
+package org.tikv.common.operation.iterator;
 
 import com.google.protobuf.ByteString;
-import org.tikv.TiSession;
+import org.tikv.common.TiSession;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Metapb;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class ConcreteScanIterator extends ScanIterator {
   private final long version;
diff --git a/src/main/java/org/tikv/operation/iterator/RawScanIterator.java b/src/main/java/org/tikv/common/operation/iterator/RawScanIterator.java
similarity index 84%
rename from src/main/java/org/tikv/operation/iterator/RawScanIterator.java
rename to src/main/java/org/tikv/common/operation/iterator/RawScanIterator.java
index d4928c9589..69444f18dd 100644
--- a/src/main/java/org/tikv/operation/iterator/RawScanIterator.java
+++ b/src/main/java/org/tikv/common/operation/iterator/RawScanIterator.java
@@ -13,17 +13,17 @@
  * limitations under the License.
  */
 
-package org.tikv.operation.iterator;
+package org.tikv.common.operation.iterator;
 
 import com.google.protobuf.ByteString;
-import org.tikv.TiSession;
-import org.tikv.key.Key;
+import org.tikv.common.TiSession;
+import org.tikv.common.key.Key;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Metapb;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class RawScanIterator extends ScanIterator {
 
diff --git a/src/main/java/org/tikv/operation/iterator/ScanIterator.java b/src/main/java/org/tikv/common/operation/iterator/ScanIterator.java
similarity index 94%
rename from src/main/java/org/tikv/operation/iterator/ScanIterator.java
rename to src/main/java/org/tikv/common/operation/iterator/ScanIterator.java
index bb9edf4360..1418392be3 100644
--- a/src/main/java/org/tikv/operation/iterator/ScanIterator.java
+++ b/src/main/java/org/tikv/common/operation/iterator/ScanIterator.java
@@ -13,19 +13,19 @@
  * limitations under the License.
  */
 
-package org.tikv.operation.iterator;
+package org.tikv.common.operation.iterator;
 
 import static java.util.Objects.requireNonNull;
 
 import com.google.protobuf.ByteString;
 import java.util.Iterator;
 import java.util.List;
-import org.tikv.TiSession;
-import org.tikv.exception.TiClientInternalException;
-import org.tikv.key.Key;
+import org.tikv.common.TiSession;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.key.Key;
+import org.tikv.common.region.RegionManager;
+import org.tikv.common.region.TiRegion;
 import org.tikv.kvproto.Kvrpcpb;
-import org.tikv.region.RegionManager;
-import org.tikv.region.TiRegion;
 
 public abstract class ScanIterator implements Iterator<Kvrpcpb.KvPair> {
   protected final TiSession session;
diff --git a/src/main/java/org/tikv/policy/RetryMaxMs.java b/src/main/java/org/tikv/common/policy/RetryMaxMs.java
similarity index 89%
rename from src/main/java/org/tikv/policy/RetryMaxMs.java
rename to src/main/java/org/tikv/common/policy/RetryMaxMs.java
index af7589a6df..a569c31ccc 100644
--- a/src/main/java/org/tikv/policy/RetryMaxMs.java
+++ b/src/main/java/org/tikv/common/policy/RetryMaxMs.java
@@ -13,10 +13,10 @@
  * limitations under the License.
  */
 
-package org.tikv.policy;
+package org.tikv.common.policy;
 
-import org.tikv.operation.ErrorHandler;
-import org.tikv.util.BackOffer;
+import org.tikv.common.operation.ErrorHandler;
+import org.tikv.common.util.BackOffer;
 
 public class RetryMaxMs<T> extends RetryPolicy<T> {
   private RetryMaxMs(ErrorHandler<T> handler, BackOffer backOffer) {
diff --git a/src/main/java/org/tikv/policy/RetryPolicy.java b/src/main/java/org/tikv/common/policy/RetryPolicy.java
similarity index 90%
rename from src/main/java/org/tikv/policy/RetryPolicy.java
rename to src/main/java/org/tikv/common/policy/RetryPolicy.java
index 18c7c09427..5b439f06bf 100644
--- a/src/main/java/org/tikv/policy/RetryPolicy.java
+++ b/src/main/java/org/tikv/common/policy/RetryPolicy.java
@@ -13,15 +13,15 @@
  * limitations under the License.
  */
 
-package org.tikv.policy;
+package org.tikv.common.policy;
 
 import com.google.common.collect.ImmutableSet;
 import io.grpc.Status;
 import java.util.concurrent.Callable;
-import org.tikv.exception.GrpcException;
-import org.tikv.operation.ErrorHandler;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.operation.ErrorHandler;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
 
 public abstract class RetryPolicy<RespT> {
   BackOffer backOffer = ConcreteBackOffer.newCopNextMaxBackOff();
diff --git a/src/main/java/org/tikv/region/RegionErrorReceiver.java b/src/main/java/org/tikv/common/region/RegionErrorReceiver.java
similarity index 95%
rename from src/main/java/org/tikv/region/RegionErrorReceiver.java
rename to src/main/java/org/tikv/common/region/RegionErrorReceiver.java
index 6471cf1aba..0a81d92ba9 100644
--- a/src/main/java/org/tikv/region/RegionErrorReceiver.java
+++ b/src/main/java/org/tikv/common/region/RegionErrorReceiver.java
@@ -15,7 +15,7 @@
  *
  */
 
-package org.tikv.region;
+package org.tikv.common.region;
 
 import org.tikv.kvproto.Metapb.Store;
 
diff --git a/src/main/java/org/tikv/region/RegionManager.java b/src/main/java/org/tikv/common/region/RegionManager.java
similarity index 94%
rename from src/main/java/org/tikv/region/RegionManager.java
rename to src/main/java/org/tikv/common/region/RegionManager.java
index f41ab60cab..f7e5224f4a 100644
--- a/src/main/java/org/tikv/region/RegionManager.java
+++ b/src/main/java/org/tikv/common/region/RegionManager.java
@@ -15,10 +15,10 @@
  *
  */
 
-package org.tikv.region;
+package org.tikv.common.region;
 
-import static org.tikv.codec.KeyUtils.formatBytes;
-import static org.tikv.util.KeyRangeUtils.makeRange;
+import static org.tikv.common.codec.KeyUtils.formatBytes;
+import static org.tikv.common.util.KeyRangeUtils.makeRange;
 
 import com.google.common.collect.RangeMap;
 import com.google.common.collect.TreeRangeMap;
@@ -28,16 +28,16 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.apache.log4j.Logger;
-import org.tikv.ReadOnlyPDClient;
-import org.tikv.TiSession;
-import org.tikv.exception.GrpcException;
-import org.tikv.exception.TiClientInternalException;
-import org.tikv.key.Key;
+import org.tikv.common.ReadOnlyPDClient;
+import org.tikv.common.TiSession;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.key.Key;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Metapb.Peer;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.Metapb.StoreState;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class RegionManager {
   private static final Logger logger = Logger.getLogger(RegionManager.class);
diff --git a/src/main/java/org/tikv/region/RegionStoreClient.java b/src/main/java/org/tikv/common/region/RegionStoreClient.java
similarity index 92%
rename from src/main/java/org/tikv/region/RegionStoreClient.java
rename to src/main/java/org/tikv/common/region/RegionStoreClient.java
index 4964d4904a..af3e0f7a48 100644
--- a/src/main/java/org/tikv/region/RegionStoreClient.java
+++ b/src/main/java/org/tikv/common/region/RegionStoreClient.java
@@ -15,48 +15,34 @@
  *
  */
 
-package org.tikv.region;
+package org.tikv.common.region;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
-import static org.tikv.util.BackOffFunction.BackOffFuncType.BoRegionMiss;
-import static org.tikv.util.BackOffFunction.BackOffFuncType.BoTxnLockFast;
+import static org.tikv.common.util.BackOffFunction.BackOffFuncType.BoRegionMiss;
+import static org.tikv.common.util.BackOffFunction.BackOffFuncType.BoTxnLockFast;
 
 import com.google.protobuf.ByteString;
 import io.grpc.ManagedChannel;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
 import java.util.function.Supplier;
 import org.apache.log4j.Logger;
-import org.tikv.AbstractGRPCClient;
-import org.tikv.TiSession;
-import org.tikv.exception.*;
+import org.tikv.common.AbstractGRPCClient;
+import org.tikv.common.TiSession;
+import org.tikv.common.exception.KeyException;
+import org.tikv.common.exception.RegionException;
+import org.tikv.common.operation.KVErrorHandler;
+import org.tikv.common.util.BackOffer;
 import org.tikv.kvproto.Errorpb;
-import org.tikv.kvproto.Kvrpcpb.BatchGetRequest;
-import org.tikv.kvproto.Kvrpcpb.BatchGetResponse;
-import org.tikv.kvproto.Kvrpcpb.Context;
-import org.tikv.kvproto.Kvrpcpb.GetRequest;
-import org.tikv.kvproto.Kvrpcpb.GetResponse;
-import org.tikv.kvproto.Kvrpcpb.KvPair;
-import org.tikv.kvproto.Kvrpcpb.RawBatchPutRequest;
-import org.tikv.kvproto.Kvrpcpb.RawBatchPutResponse;
-import org.tikv.kvproto.Kvrpcpb.RawDeleteRequest;
-import org.tikv.kvproto.Kvrpcpb.RawDeleteResponse;
-import org.tikv.kvproto.Kvrpcpb.RawGetRequest;
-import org.tikv.kvproto.Kvrpcpb.RawGetResponse;
-import org.tikv.kvproto.Kvrpcpb.RawPutRequest;
-import org.tikv.kvproto.Kvrpcpb.RawPutResponse;
-import org.tikv.kvproto.Kvrpcpb.RawScanRequest;
-import org.tikv.kvproto.Kvrpcpb.RawScanResponse;
-import org.tikv.kvproto.Kvrpcpb.ScanRequest;
-import org.tikv.kvproto.Kvrpcpb.ScanResponse;
+import org.tikv.kvproto.Kvrpcpb.*;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.TikvGrpc;
 import org.tikv.kvproto.TikvGrpc.TikvBlockingStub;
 import org.tikv.kvproto.TikvGrpc.TikvStub;
-import org.tikv.operation.KVErrorHandler;
 import org.tikv.txn.Lock;
 import org.tikv.txn.LockResolverClient;
-import org.tikv.util.BackOffer;
 
 // RegionStore itself is not thread-safe
 public class RegionStoreClient extends AbstractGRPCClient<TikvBlockingStub, TikvStub>
diff --git a/src/main/java/org/tikv/region/TiRegion.java b/src/main/java/org/tikv/common/region/TiRegion.java
similarity index 95%
rename from src/main/java/org/tikv/region/TiRegion.java
rename to src/main/java/org/tikv/common/region/TiRegion.java
index e78d907738..89db52c580 100644
--- a/src/main/java/org/tikv/region/TiRegion.java
+++ b/src/main/java/org/tikv/common/region/TiRegion.java
@@ -15,7 +15,7 @@
  *
  */
 
-package org.tikv.region;
+package org.tikv.common.region;
 
 import com.google.protobuf.ByteString;
 import java.io.Serializable;
@@ -23,16 +23,16 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
-import org.tikv.codec.Codec.BytesCodec;
-import org.tikv.codec.CodecDataInput;
-import org.tikv.codec.KeyUtils;
-import org.tikv.exception.TiClientInternalException;
+import org.tikv.common.codec.Codec.BytesCodec;
+import org.tikv.common.codec.CodecDataInput;
+import org.tikv.common.codec.KeyUtils;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.util.FastByteComparisons;
 import org.tikv.kvproto.Kvrpcpb;
 import org.tikv.kvproto.Kvrpcpb.IsolationLevel;
 import org.tikv.kvproto.Metapb;
 import org.tikv.kvproto.Metapb.Peer;
 import org.tikv.kvproto.Metapb.Region;
-import org.tikv.util.FastByteComparisons;
 
 public class TiRegion implements Serializable {
   private final Region meta;
diff --git a/src/main/java/org/tikv/streaming/StreamingResponse.java b/src/main/java/org/tikv/common/streaming/StreamingResponse.java
similarity index 98%
rename from src/main/java/org/tikv/streaming/StreamingResponse.java
rename to src/main/java/org/tikv/common/streaming/StreamingResponse.java
index 11b81765c2..936e144840 100644
--- a/src/main/java/org/tikv/streaming/StreamingResponse.java
+++ b/src/main/java/org/tikv/common/streaming/StreamingResponse.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.streaming;
+package org.tikv.common.streaming;
 
 import static java.util.Objects.requireNonNull;
 
diff --git a/src/main/java/org/tikv/util/BackOffFunction.java b/src/main/java/org/tikv/common/util/BackOffFunction.java
similarity index 95%
rename from src/main/java/org/tikv/util/BackOffFunction.java
rename to src/main/java/org/tikv/common/util/BackOffFunction.java
index c99aa08355..83348a0e2e 100644
--- a/src/main/java/org/tikv/util/BackOffFunction.java
+++ b/src/main/java/org/tikv/common/util/BackOffFunction.java
@@ -1,7 +1,7 @@
-package org.tikv.util;
+package org.tikv.common.util;
 
 import java.util.concurrent.ThreadLocalRandom;
-import org.tikv.exception.GrpcException;
+import org.tikv.common.exception.GrpcException;
 
 public class BackOffFunction {
   private int base;
diff --git a/src/main/java/org/tikv/util/BackOffer.java b/src/main/java/org/tikv/common/util/BackOffer.java
similarity index 98%
rename from src/main/java/org/tikv/util/BackOffer.java
rename to src/main/java/org/tikv/common/util/BackOffer.java
index c7744c9a5c..9820b46d03 100644
--- a/src/main/java/org/tikv/util/BackOffer.java
+++ b/src/main/java/org/tikv/common/util/BackOffer.java
@@ -15,7 +15,7 @@
  *
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
 public interface BackOffer {
   // Back off strategies
diff --git a/src/main/java/org/tikv/util/ConcreteBackOffer.java b/src/main/java/org/tikv/common/util/ConcreteBackOffer.java
similarity index 98%
rename from src/main/java/org/tikv/util/ConcreteBackOffer.java
rename to src/main/java/org/tikv/common/util/ConcreteBackOffer.java
index 0fbc5b76aa..722e918873 100644
--- a/src/main/java/org/tikv/util/ConcreteBackOffer.java
+++ b/src/main/java/org/tikv/common/util/ConcreteBackOffer.java
@@ -15,7 +15,7 @@
  *
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
 import com.google.common.base.Preconditions;
 import java.util.ArrayList;
@@ -23,7 +23,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.apache.log4j.Logger;
-import org.tikv.exception.GrpcException;
+import org.tikv.common.exception.GrpcException;
 
 public class ConcreteBackOffer implements BackOffer {
   private int maxSleep;
diff --git a/src/main/java/org/tikv/util/FastByteComparisons.java b/src/main/java/org/tikv/common/util/FastByteComparisons.java
similarity index 99%
rename from src/main/java/org/tikv/util/FastByteComparisons.java
rename to src/main/java/org/tikv/common/util/FastByteComparisons.java
index 644f23ffed..047c637a54 100644
--- a/src/main/java/org/tikv/util/FastByteComparisons.java
+++ b/src/main/java/org/tikv/common/util/FastByteComparisons.java
@@ -12,7 +12,7 @@
  * express or implied. See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.tikv.util;
+package org.tikv.common.util;
 
 import com.google.common.primitives.Longs;
 import com.google.common.primitives.UnsignedBytes;
diff --git a/src/main/java/org/tikv/util/FutureObserver.java b/src/main/java/org/tikv/common/util/FutureObserver.java
similarity index 97%
rename from src/main/java/org/tikv/util/FutureObserver.java
rename to src/main/java/org/tikv/common/util/FutureObserver.java
index f758aec7ec..e1757e80d5 100644
--- a/src/main/java/org/tikv/util/FutureObserver.java
+++ b/src/main/java/org/tikv/common/util/FutureObserver.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
 import com.google.common.util.concurrent.SettableFuture;
 import io.grpc.stub.StreamObserver;
diff --git a/src/main/java/org/tikv/util/KeyRangeUtils.java b/src/main/java/org/tikv/common/util/KeyRangeUtils.java
similarity index 96%
rename from src/main/java/org/tikv/util/KeyRangeUtils.java
rename to src/main/java/org/tikv/common/util/KeyRangeUtils.java
index 821f6b37be..f46da182b9 100644
--- a/src/main/java/org/tikv/util/KeyRangeUtils.java
+++ b/src/main/java/org/tikv/common/util/KeyRangeUtils.java
@@ -13,17 +13,17 @@
  * limitations under the License.
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
-import static org.tikv.key.Key.toRawKey;
+import static org.tikv.common.key.Key.toRawKey;
 
 import com.google.common.collect.BoundType;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Range;
 import com.google.protobuf.ByteString;
 import java.util.List;
-import org.tikv.exception.TiClientInternalException;
-import org.tikv.key.Key;
+import org.tikv.common.exception.TiClientInternalException;
+import org.tikv.common.key.Key;
 import org.tikv.kvproto.Coprocessor.KeyRange;
 
 public class KeyRangeUtils {
diff --git a/src/main/java/org/tikv/util/Pair.java b/src/main/java/org/tikv/common/util/Pair.java
similarity index 96%
rename from src/main/java/org/tikv/util/Pair.java
rename to src/main/java/org/tikv/common/util/Pair.java
index d5761a11f7..7b6abb6880 100644
--- a/src/main/java/org/tikv/util/Pair.java
+++ b/src/main/java/org/tikv/common/util/Pair.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
 import java.io.Serializable;
 
diff --git a/src/main/java/org/tikv/util/Timer.java b/src/main/java/org/tikv/common/util/Timer.java
similarity index 96%
rename from src/main/java/org/tikv/util/Timer.java
rename to src/main/java/org/tikv/common/util/Timer.java
index 9da4a418be..2e0dd02b89 100644
--- a/src/main/java/org/tikv/util/Timer.java
+++ b/src/main/java/org/tikv/common/util/Timer.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv.util;
+package org.tikv.common.util;
 
 import java.util.concurrent.TimeUnit;
 
diff --git a/src/main/java/org/tikv/util/TsoUtils.java b/src/main/java/org/tikv/common/util/TsoUtils.java
similarity index 93%
rename from src/main/java/org/tikv/util/TsoUtils.java
rename to src/main/java/org/tikv/common/util/TsoUtils.java
index d4603a8a05..feb1b5413e 100644
--- a/src/main/java/org/tikv/util/TsoUtils.java
+++ b/src/main/java/org/tikv/common/util/TsoUtils.java
@@ -1,4 +1,4 @@
-package org.tikv.util;
+package org.tikv.common.util;
 
 public final class TsoUtils {
   private static final long physicalShiftBits = 18;
diff --git a/src/main/java/org/tikv/RawKVClient.java b/src/main/java/org/tikv/raw/RawKVClient.java
similarity index 91%
rename from src/main/java/org/tikv/RawKVClient.java
rename to src/main/java/org/tikv/raw/RawKVClient.java
index 5f886a8d44..e1e93a3ee2 100644
--- a/src/main/java/org/tikv/RawKVClient.java
+++ b/src/main/java/org/tikv/raw/RawKVClient.java
@@ -1,16 +1,18 @@
-package org.tikv;
+package org.tikv.raw;
 
 import com.google.protobuf.ByteString;
 import java.util.*;
+import org.tikv.common.TiConfiguration;
+import org.tikv.common.TiSession;
+import org.tikv.common.operation.iterator.RawScanIterator;
+import org.tikv.common.region.RegionManager;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Kvrpcpb;
 import org.tikv.kvproto.Metapb;
-import org.tikv.operation.iterator.RawScanIterator;
-import org.tikv.region.RegionManager;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class RawKVClient {
   private static final String DEFAULT_PD_ADDRESS = "127.0.0.1:2379";
diff --git a/src/main/java/org/tikv/txn/LockResolverClient.java b/src/main/java/org/tikv/txn/LockResolverClient.java
index 293e51b1fa..07d5ae9a89 100644
--- a/src/main/java/org/tikv/txn/LockResolverClient.java
+++ b/src/main/java/org/tikv/txn/LockResolverClient.java
@@ -17,7 +17,7 @@
 
 package org.tikv.txn;
 
-import static org.tikv.util.BackOffFunction.BackOffFuncType.BoRegionMiss;
+import static org.tikv.common.util.BackOffFunction.BackOffFuncType.BoRegionMiss;
 
 import com.google.protobuf.ByteString;
 import io.grpc.ManagedChannel;
@@ -26,10 +26,16 @@ import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.function.Supplier;
 import org.apache.log4j.Logger;
-import org.tikv.AbstractGRPCClient;
-import org.tikv.TiSession;
-import org.tikv.exception.KeyException;
-import org.tikv.exception.RegionException;
+import org.tikv.common.AbstractGRPCClient;
+import org.tikv.common.TiSession;
+import org.tikv.common.exception.KeyException;
+import org.tikv.common.exception.RegionException;
+import org.tikv.common.operation.KVErrorHandler;
+import org.tikv.common.region.RegionErrorReceiver;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.region.TiRegion.RegionVerID;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.TsoUtils;
 import org.tikv.kvproto.Kvrpcpb.CleanupRequest;
 import org.tikv.kvproto.Kvrpcpb.CleanupResponse;
 import org.tikv.kvproto.Kvrpcpb.ResolveLockRequest;
@@ -38,12 +44,6 @@ import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.TikvGrpc;
 import org.tikv.kvproto.TikvGrpc.TikvBlockingStub;
 import org.tikv.kvproto.TikvGrpc.TikvStub;
-import org.tikv.operation.KVErrorHandler;
-import org.tikv.region.RegionErrorReceiver;
-import org.tikv.region.TiRegion;
-import org.tikv.region.TiRegion.RegionVerID;
-import org.tikv.util.BackOffer;
-import org.tikv.util.TsoUtils;
 
 // LockResolver resolves locks and also caches resolved txn status.
 public class LockResolverClient extends AbstractGRPCClient<TikvBlockingStub, TikvStub>
diff --git a/src/main/java/org/tikv/txn/TxnKVClient.java b/src/main/java/org/tikv/txn/TxnKVClient.java
new file mode 100644
index 0000000000..65e0db092d
--- /dev/null
+++ b/src/main/java/org/tikv/txn/TxnKVClient.java
@@ -0,0 +1,5 @@
+package org.tikv.txn;
+
+public class TxnKVClient {
+  // TODO: To be done.
+}
diff --git a/src/main/java/org/tikv/txn/exception/LockException.java b/src/main/java/org/tikv/txn/exception/LockException.java
new file mode 100644
index 0000000000..9f7afa527b
--- /dev/null
+++ b/src/main/java/org/tikv/txn/exception/LockException.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2017 PingCAP, Inc.
+ *
+ * Licensed 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,
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.tikv.txn.exception;
+
+import org.tikv.txn.Lock;
+
+public class LockException extends RuntimeException {
+  private final Lock lock;
+
+  public LockException(Lock lock) {
+    this.lock = lock;
+  }
+
+  public Lock getLock() {
+    return lock;
+  }
+}
diff --git a/src/test/java/org/tikv/GrpcUtils.java b/src/test/java/org/tikv/common/GrpcUtils.java
similarity index 96%
rename from src/test/java/org/tikv/GrpcUtils.java
rename to src/test/java/org/tikv/common/GrpcUtils.java
index 28041cd17c..c2c2e06b8c 100644
--- a/src/test/java/org/tikv/GrpcUtils.java
+++ b/src/test/java/org/tikv/common/GrpcUtils.java
@@ -13,13 +13,13 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import com.google.common.collect.Lists;
 import com.google.protobuf.ByteString;
 import java.util.Arrays;
-import org.tikv.codec.Codec.BytesCodec;
-import org.tikv.codec.CodecDataOutput;
+import org.tikv.common.codec.Codec.BytesCodec;
+import org.tikv.common.codec.CodecDataOutput;
 import org.tikv.kvproto.Metapb.*;
 import org.tikv.kvproto.Pdpb.*;
 
diff --git a/src/test/java/org/tikv/KVMockServer.java b/src/test/java/org/tikv/common/KVMockServer.java
similarity index 97%
rename from src/test/java/org/tikv/KVMockServer.java
rename to src/test/java/org/tikv/common/KVMockServer.java
index e3eb7cdf3b..7c1ef2fa9f 100644
--- a/src/test/java/org/tikv/KVMockServer.java
+++ b/src/test/java/org/tikv/common/KVMockServer.java
@@ -13,9 +13,9 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
-import static org.tikv.key.Key.toRawKey;
+import static org.tikv.common.key.Key.toRawKey;
 
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.ByteString;
@@ -27,14 +27,10 @@ import io.grpc.ServerBuilder;
 import io.grpc.Status;
 import java.io.IOException;
 import java.net.ServerSocket;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-import java.util.SortedMap;
-import java.util.TreeMap;
+import java.util.*;
 import java.util.stream.Collectors;
-import org.tikv.key.Key;
+import org.tikv.common.key.Key;
+import org.tikv.common.region.TiRegion;
 import org.tikv.kvproto.Coprocessor;
 import org.tikv.kvproto.Errorpb;
 import org.tikv.kvproto.Errorpb.Error;
@@ -44,7 +40,6 @@ import org.tikv.kvproto.Errorpb.StaleEpoch;
 import org.tikv.kvproto.Kvrpcpb;
 import org.tikv.kvproto.Kvrpcpb.Context;
 import org.tikv.kvproto.TikvGrpc;
-import org.tikv.region.TiRegion;
 
 public class KVMockServer extends TikvGrpc.TikvImplBase {
 
diff --git a/src/test/java/org/tikv/MockServerTest.java b/src/test/java/org/tikv/common/MockServerTest.java
similarity index 96%
rename from src/test/java/org/tikv/MockServerTest.java
rename to src/test/java/org/tikv/common/MockServerTest.java
index bc765bf5b5..2d46100902 100644
--- a/src/test/java/org/tikv/MockServerTest.java
+++ b/src/test/java/org/tikv/common/MockServerTest.java
@@ -1,14 +1,14 @@
-package org.tikv;
+package org.tikv.common;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.protobuf.ByteString;
 import org.junit.After;
 import org.junit.Before;
+import org.tikv.common.region.TiRegion;
 import org.tikv.kvproto.Coprocessor;
 import org.tikv.kvproto.Kvrpcpb;
 import org.tikv.kvproto.Metapb;
 import org.tikv.kvproto.Pdpb;
-import org.tikv.region.TiRegion;
 
 public class MockServerTest {
   public KVMockServer server;
diff --git a/src/test/java/org/tikv/PDClientTest.java b/src/test/java/org/tikv/common/PDClientTest.java
similarity index 96%
rename from src/test/java/org/tikv/PDClientTest.java
rename to src/test/java/org/tikv/common/PDClientTest.java
index dce72cf6b2..21c7b00349 100644
--- a/src/test/java/org/tikv/PDClientTest.java
+++ b/src/test/java/org/tikv/common/PDClientTest.java
@@ -13,12 +13,10 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-import static org.tikv.GrpcUtils.encodeKey;
+import static org.junit.Assert.*;
+import static org.tikv.common.GrpcUtils.encodeKey;
 
 import com.google.protobuf.ByteString;
 import java.io.IOException;
@@ -26,14 +24,14 @@ import java.util.concurrent.*;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
-import org.tikv.exception.GrpcException;
+import org.tikv.common.exception.GrpcException;
+import org.tikv.common.meta.TiTimestamp;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
 import org.tikv.kvproto.Metapb;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.Metapb.StoreState;
-import org.tikv.meta.TiTimestamp;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
 
 public class PDClientTest {
 
diff --git a/src/test/java/org/tikv/PDMockServer.java b/src/test/java/org/tikv/common/PDMockServer.java
similarity index 99%
rename from src/test/java/org/tikv/PDMockServer.java
rename to src/test/java/org/tikv/common/PDMockServer.java
index 6aa5d4acdf..81e9c64bd2 100644
--- a/src/test/java/org/tikv/PDMockServer.java
+++ b/src/test/java/org/tikv/common/PDMockServer.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import io.grpc.Server;
 import io.grpc.ServerBuilder;
diff --git a/src/test/java/org/tikv/RegionManagerTest.java b/src/test/java/org/tikv/common/RegionManagerTest.java
similarity index 97%
rename from src/test/java/org/tikv/RegionManagerTest.java
rename to src/test/java/org/tikv/common/RegionManagerTest.java
index 380d526994..187a1486f5 100644
--- a/src/test/java/org/tikv/RegionManagerTest.java
+++ b/src/test/java/org/tikv/common/RegionManagerTest.java
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import static org.junit.Assert.*;
 
@@ -22,12 +22,12 @@ import java.io.IOException;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.tikv.common.region.RegionManager;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Metapb;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.Metapb.StoreState;
-import org.tikv.region.RegionManager;
-import org.tikv.region.TiRegion;
-import org.tikv.util.Pair;
 
 public class RegionManagerTest {
   private PDMockServer server;
diff --git a/src/test/java/org/tikv/RegionStoreClientTest.java b/src/test/java/org/tikv/common/RegionStoreClientTest.java
similarity index 95%
rename from src/test/java/org/tikv/RegionStoreClientTest.java
rename to src/test/java/org/tikv/common/RegionStoreClientTest.java
index 6b4c38f720..01acfc0ca0 100644
--- a/src/test/java/org/tikv/RegionStoreClientTest.java
+++ b/src/test/java/org/tikv/common/RegionStoreClientTest.java
@@ -13,20 +13,19 @@
  * limitations under the License.
  */
 
-package org.tikv;
+package org.tikv.common;
 
 import static org.junit.Assert.*;
 
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.ByteString;
-import com.pingcap.tidb.tipb.*;
-import java.util.*;
+import java.util.List;
 import org.junit.Test;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
 import org.tikv.kvproto.Kvrpcpb;
 import org.tikv.kvproto.Metapb;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
 
 public class RegionStoreClientTest extends MockServerTest {
 
diff --git a/src/test/java/org/tikv/codec/CodecTest.java b/src/test/java/org/tikv/common/codec/CodecTest.java
similarity index 98%
rename from src/test/java/org/tikv/codec/CodecTest.java
rename to src/test/java/org/tikv/common/codec/CodecTest.java
index 5a8cc242fc..ee474b69aa 100644
--- a/src/test/java/org/tikv/codec/CodecTest.java
+++ b/src/test/java/org/tikv/common/codec/CodecTest.java
@@ -13,13 +13,13 @@
  * limitations under the License.
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import static org.junit.Assert.*;
-import static org.tikv.codec.Codec.*;
+import static org.tikv.common.codec.Codec.*;
 
 import org.junit.Test;
-import org.tikv.codec.Codec.*;
+import org.tikv.common.codec.Codec.*;
 
 public class CodecTest {
   @Test
diff --git a/src/test/java/org/tikv/codec/MyDecimalTest.java b/src/test/java/org/tikv/common/codec/MyDecimalTest.java
similarity index 99%
rename from src/test/java/org/tikv/codec/MyDecimalTest.java
rename to src/test/java/org/tikv/common/codec/MyDecimalTest.java
index d55866ca15..f816ed3620 100644
--- a/src/test/java/org/tikv/codec/MyDecimalTest.java
+++ b/src/test/java/org/tikv/common/codec/MyDecimalTest.java
@@ -15,7 +15,7 @@
  *
  */
 
-package org.tikv.codec;
+package org.tikv.common.codec;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
diff --git a/src/test/java/org/tikv/key/KeyTest.java b/src/test/java/org/tikv/common/key/KeyTest.java
similarity index 88%
rename from src/test/java/org/tikv/key/KeyTest.java
rename to src/test/java/org/tikv/common/key/KeyTest.java
index c391027294..60b876ff4e 100644
--- a/src/test/java/org/tikv/key/KeyTest.java
+++ b/src/test/java/org/tikv/common/key/KeyTest.java
@@ -13,10 +13,10 @@
  * limitations under the License.
  */
 
-package org.tikv.key;
+package org.tikv.common.key;
 
-import static org.junit.Assert.*;
-import static org.tikv.key.Key.toRawKey;
+import static org.junit.Assert.assertEquals;
+import static org.tikv.common.key.Key.toRawKey;
 
 import com.google.common.primitives.UnsignedBytes;
 import org.junit.Test;
diff --git a/src/test/java/org/tikv/RawKVClientTest.java b/src/test/java/org/tikv/raw/RawKVClientTest.java
similarity index 99%
rename from src/test/java/org/tikv/RawKVClientTest.java
rename to src/test/java/org/tikv/raw/RawKVClientTest.java
index 552536acd6..0b65dcecbb 100644
--- a/src/test/java/org/tikv/RawKVClientTest.java
+++ b/src/test/java/org/tikv/raw/RawKVClientTest.java
@@ -1,4 +1,4 @@
-package org.tikv;
+package org.tikv.raw;
 
 import com.google.protobuf.ByteString;
 import java.util.*;
@@ -7,9 +7,9 @@ import java.util.stream.Collectors;
 import org.apache.commons.lang3.RandomStringUtils;
 import org.junit.Before;
 import org.junit.Test;
-import org.tikv.key.Key;
+import org.tikv.common.key.Key;
+import org.tikv.common.util.FastByteComparisons;
 import org.tikv.kvproto.Kvrpcpb;
-import org.tikv.util.FastByteComparisons;
 
 public class RawKVClientTest {
   private static final String RAW_PREFIX = "raw_\\u0001_";
diff --git a/src/test/java/org/tikv/txn/LockResolverTest.java b/src/test/java/org/tikv/txn/LockResolverTest.java
index 2029402456..e057cbd34b 100644
--- a/src/test/java/org/tikv/txn/LockResolverTest.java
+++ b/src/test/java/org/tikv/txn/LockResolverTest.java
@@ -16,39 +16,33 @@
 package org.tikv.txn;
 
 import static junit.framework.TestCase.*;
-import static org.tikv.util.BackOffFunction.BackOffFuncType.BoTxnLock;
+import static org.tikv.common.util.BackOffFunction.BackOffFuncType.BoTxnLock;
 
 import com.google.protobuf.ByteString;
-import com.pingcap.tidb.tipb.*;
 import java.lang.reflect.Field;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
 import java.util.function.Supplier;
 import org.junit.Before;
 import org.junit.Test;
-import org.tikv.PDClient;
-import org.tikv.ReadOnlyPDClient;
-import org.tikv.TiConfiguration;
-import org.tikv.TiSession;
-import org.tikv.exception.KeyException;
-import org.tikv.exception.RegionException;
+import org.tikv.common.PDClient;
+import org.tikv.common.ReadOnlyPDClient;
+import org.tikv.common.TiConfiguration;
+import org.tikv.common.TiSession;
+import org.tikv.common.exception.KeyException;
+import org.tikv.common.exception.RegionException;
+import org.tikv.common.meta.TiTimestamp;
+import org.tikv.common.operation.KVErrorHandler;
+import org.tikv.common.region.RegionStoreClient;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.util.BackOffer;
+import org.tikv.common.util.ConcreteBackOffer;
+import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Coprocessor;
-import org.tikv.kvproto.Kvrpcpb.CommitRequest;
-import org.tikv.kvproto.Kvrpcpb.CommitResponse;
-import org.tikv.kvproto.Kvrpcpb.IsolationLevel;
-import org.tikv.kvproto.Kvrpcpb.KeyError;
-import org.tikv.kvproto.Kvrpcpb.Mutation;
-import org.tikv.kvproto.Kvrpcpb.Op;
-import org.tikv.kvproto.Kvrpcpb.PrewriteRequest;
-import org.tikv.kvproto.Kvrpcpb.PrewriteResponse;
+import org.tikv.kvproto.Kvrpcpb.*;
 import org.tikv.kvproto.Metapb.Store;
 import org.tikv.kvproto.TikvGrpc;
-import org.tikv.meta.TiTimestamp;
-import org.tikv.operation.KVErrorHandler;
-import org.tikv.region.RegionStoreClient;
-import org.tikv.region.TiRegion;
-import org.tikv.util.BackOffer;
-import org.tikv.util.ConcreteBackOffer;
-import org.tikv.util.Pair;
 
 public class LockResolverTest {
   private TiSession session;