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/*
*
* Copyright 2019 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.common;
import static org.tikv.common.util.ClientUtils.appendBatches;
import static org.tikv.common.util.ClientUtils.getKvPairs;
import com.google.protobuf.ByteString;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.stream.Collectors;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.tikv.common.exception.GrpcException;
import org.tikv.common.exception.TiKVException;
import org.tikv.common.operation.iterator.ConcreteScanIterator;
import org.tikv.common.region.RegionStoreClient;
import org.tikv.common.region.RegionStoreClient.RegionStoreClientBuilder;
import org.tikv.common.region.TiRegion;
import org.tikv.common.util.BackOffFunction;
import org.tikv.common.util.BackOffer;
import org.tikv.common.util.Batch;
import org.tikv.common.util.ConcreteBackOffer;
import org.tikv.kvproto.Kvrpcpb.KvPair;
public class KVClient implements AutoCloseable {
private static final Logger logger = LoggerFactory.getLogger(KVClient.class);
private static final int BATCH_GET_SIZE = 16 * 1024;
private final RegionStoreClientBuilder clientBuilder;
private final TiConfiguration conf;
private final ExecutorService batchGetThreadPool;
public KVClient(TiSession session, RegionStoreClientBuilder clientBuilder) {
Objects.requireNonNull(clientBuilder, "clientBuilder is null");
this.conf = session.getConf();
this.clientBuilder = clientBuilder;
this.batchGetThreadPool = session.getThreadPoolForBatchGet();
}
@Override
public void close() {}
/**
* Get a key-value pair from TiKV if key exists
*
* @param key key
* @return a ByteString value if key exists, ByteString.EMPTY if key does not exist
*/
public ByteString get(ByteString key, long version) throws GrpcException {
BackOffer backOffer = ConcreteBackOffer.newGetBackOff();
while (true) {
RegionStoreClient client = clientBuilder.build(key);
try {
return client.get(backOffer, key, version);
} catch (final TiKVException e) {
backOffer.doBackOff(BackOffFunction.BackOffFuncType.BoRegionMiss, e);
}
}
}
/**
* Get a set of key-value pair by keys from TiKV
*
* @param backOffer
* @param keys
* @param version
* @return
* @throws GrpcException
*/
public List<KvPair> batchGet(BackOffer backOffer, List<ByteString> keys, long version)
throws GrpcException {
return doSendBatchGet(backOffer, keys, version);
}
/**
* Scan key-value pairs from TiKV in range [startKey, endKey)
*
* @param startKey start key, inclusive
* @param endKey end key, exclusive
* @return list of key-value pairs in range
*/
public List<KvPair> scan(ByteString startKey, ByteString endKey, long version)
throws GrpcException {
Iterator<KvPair> iterator = scanIterator(conf, clientBuilder, startKey, endKey, version);
List<KvPair> result = new ArrayList<>();
iterator.forEachRemaining(result::add);
return result;
}
/**
* Scan key-value pairs from TiKV in range [startKey, ♾), maximum to `limit` pairs
*
* @param startKey start key, inclusive
* @param limit limit of kv pairs
* @return list of key-value pairs in range
*/
public List<KvPair> scan(ByteString startKey, long version, int limit) throws GrpcException {
Iterator<KvPair> iterator = scanIterator(conf, clientBuilder, startKey, version, limit);
List<KvPair> result = new ArrayList<>();
iterator.forEachRemaining(result::add);
return result;
}
public List<KvPair> scan(ByteString startKey, long version) throws GrpcException {
return scan(startKey, version, Integer.MAX_VALUE);
}
private List<KvPair> doSendBatchGet(BackOffer backOffer, List<ByteString> keys, long version) {
ExecutorCompletionService<List<KvPair>> completionService =
new ExecutorCompletionService<>(batchGetThreadPool);
Map<TiRegion, List<ByteString>> groupKeys = groupKeysByRegion(keys);
List<Batch> batches = new ArrayList<>();
for (Map.Entry<TiRegion, List<ByteString>> entry : groupKeys.entrySet()) {
appendBatches(batches, entry.getKey(), entry.getValue(), BATCH_GET_SIZE);
}
for (Batch batch : batches) {
BackOffer singleBatchBackOffer = ConcreteBackOffer.create(backOffer);
completionService.submit(
() -> doSendBatchGetInBatchesWithRetry(singleBatchBackOffer, batch, version));
}
return getKvPairs(completionService, batches, BackOffer.BATCH_GET_MAX_BACKOFF);
}
private List<KvPair> doSendBatchGetInBatchesWithRetry(
BackOffer backOffer, Batch batch, long version) {
TiRegion oldRegion = batch.region;
TiRegion currentRegion =
clientBuilder.getRegionManager().getRegionByKey(oldRegion.getStartKey());
if (oldRegion.equals(currentRegion)) {
RegionStoreClient client = clientBuilder.build(batch.region);
try {
return client.batchGet(backOffer, batch.keys, version);
} catch (final TiKVException e) {
backOffer.doBackOff(BackOffFunction.BackOffFuncType.BoRegionMiss, e);
clientBuilder.getRegionManager().invalidateRegion(batch.region.getId());
logger.warn("ReSplitting ranges for BatchGetRequest", e);
// retry
return doSendBatchGetWithRefetchRegion(backOffer, batch, version);
}
} else {
return doSendBatchGetWithRefetchRegion(backOffer, batch, version);
}
}
private List<KvPair> doSendBatchGetWithRefetchRegion(
BackOffer backOffer, Batch batch, long version) {
Map<TiRegion, List<ByteString>> groupKeys = groupKeysByRegion(batch.keys);
List<Batch> retryBatches = new ArrayList<>();
for (Map.Entry<TiRegion, List<ByteString>> entry : groupKeys.entrySet()) {
appendBatches(retryBatches, entry.getKey(), entry.getValue(), BATCH_GET_SIZE);
}
ArrayList<KvPair> results = new ArrayList<>();
for (Batch retryBatch : retryBatches) {
// recursive calls
List<KvPair> batchResult = doSendBatchGetInBatchesWithRetry(backOffer, retryBatch, version);
results.addAll(batchResult);
}
return results;
}
/**
* Group by list of keys according to its region
*
* @param keys keys
* @return a mapping of keys and their region
*/
private Map<TiRegion, List<ByteString>> groupKeysByRegion(List<ByteString> keys) {
return keys.stream()
.collect(Collectors.groupingBy(clientBuilder.getRegionManager()::getRegionByKey));
}
private Iterator<KvPair> scanIterator(
TiConfiguration conf,
RegionStoreClientBuilder builder,
ByteString startKey,
ByteString endKey,
long version) {
return new ConcreteScanIterator(conf, builder, startKey, endKey, version);
}
private Iterator<KvPair> scanIterator(
TiConfiguration conf,
RegionStoreClientBuilder builder,
ByteString startKey,
long version,
int limit) {
return new ConcreteScanIterator(conf, builder, startKey, version, limit);
}
}