HBASE-13071 Hbase Streaming Scan Feature

Signed-off-by: stack <stack@apache.org>
This commit is contained in:
eshcar 2015-05-10 11:11:44 +03:00 committed by stack
parent 220ac141bf
commit 86b91997d0
12 changed files with 481 additions and 67 deletions

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@ -0,0 +1,234 @@
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* 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 KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.client;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
import org.apache.hadoop.hbase.util.Threads;
import java.io.IOException;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
/**
* ClientAsyncPrefetchScanner implements async scanner behaviour.
* Specifically, the cache used by this scanner is a concurrent queue which allows both
* the producer (hbase client) and consumer (application) to access the queue in parallel.
* The number of rows returned in a prefetch is defined by the caching factor and the result size
* factor.
* This class allocates a buffer cache, whose size is a function of both factors.
* The prefetch is invoked when the cache is half­filled, instead of waiting for it to be empty.
* This is defined in the method {@link ClientAsyncPrefetchScanner#prefetchCondition()}.
*/
@InterfaceAudience.Private
public class ClientAsyncPrefetchScanner extends ClientScanner {
private static final int ESTIMATED_SINGLE_RESULT_SIZE = 1024;
private static final int DEFAULT_QUEUE_CAPACITY = 1024;
private int cacheCapacity;
private AtomicLong cacheSizeInBytes;
// exception queue (from prefetch to main scan execution)
private Queue<Exception> exceptionsQueue;
// prefetch runnable object to be executed asynchronously
private PrefetchRunnable prefetchRunnable;
// Boolean flag to ensure only a single prefetch is running (per scan)
// We use atomic boolean to allow multiple concurrent threads to
// consume records from the same cache, but still have a single prefetcher thread.
// For a single consumer thread this can be replace with a native boolean.
private AtomicBoolean prefetchRunning;
// an attribute for synchronizing close between scanner and prefetch threads
private AtomicLong closingThreadId;
private static final int NO_THREAD = -1;
public ClientAsyncPrefetchScanner(Configuration configuration, Scan scan, TableName name,
ClusterConnection connection, RpcRetryingCallerFactory rpcCallerFactory,
RpcControllerFactory rpcControllerFactory, ExecutorService pool,
int replicaCallTimeoutMicroSecondScan) throws IOException {
super(configuration, scan, name, connection, rpcCallerFactory, rpcControllerFactory, pool,
replicaCallTimeoutMicroSecondScan);
}
@Override
protected void initCache() {
// concurrent cache
cacheCapacity = calcCacheCapacity();
cache = new LinkedBlockingQueue<Result>(cacheCapacity);
cacheSizeInBytes = new AtomicLong(0);
exceptionsQueue = new ConcurrentLinkedQueue<Exception>();
prefetchRunnable = new PrefetchRunnable();
prefetchRunning = new AtomicBoolean(false);
closingThreadId = new AtomicLong(NO_THREAD);
}
@Override
public Result next() throws IOException {
try {
handleException();
// If the scanner is closed and there's nothing left in the cache, next is a no-op.
if (getCacheCount() == 0 && this.closed) {
return null;
}
if (prefetchCondition()) {
// run prefetch in the background only if no prefetch is already running
if (!isPrefetchRunning()) {
if (prefetchRunning.compareAndSet(false, true)) {
getPool().execute(prefetchRunnable);
}
}
}
while (isPrefetchRunning()) {
// prefetch running or still pending
if (getCacheCount() > 0) {
Result res = cache.poll();
long estimatedSize = calcEstimatedSize(res);
addEstimatedSize(-estimatedSize);
return res;
} else {
// (busy) wait for a record - sleep
Threads.sleep(1);
}
}
if (getCacheCount() > 0) {
return cache.poll();
}
// if we exhausted this scanner before calling close, write out the scan metrics
writeScanMetrics();
return null;
} finally {
handleException();
}
}
@Override
public void close() {
if (!scanMetricsPublished) writeScanMetrics();
closed = true;
if (!isPrefetchRunning()) {
if(closingThreadId.compareAndSet(NO_THREAD, Thread.currentThread().getId())) {
super.close();
}
} // else do nothing since the async prefetch still needs this resources
}
@Override
public int getCacheCount() {
if(cache != null) {
int size = cache.size();
if(size > cacheCapacity) {
cacheCapacity = size;
}
return size;
} else {
return 0;
}
}
@Override
protected void addEstimatedSize(long estimatedSize) {
cacheSizeInBytes.addAndGet(estimatedSize);
}
private void handleException() throws IOException {
//The prefetch task running in the background puts any exception it
//catches into this exception queue.
// Rethrow the exception so the application can handle it.
while (!exceptionsQueue.isEmpty()) {
Exception first = exceptionsQueue.peek();
first.printStackTrace();
if (first instanceof IOException) {
throw (IOException) first;
}
throw (RuntimeException) first;
}
}
private boolean isPrefetchRunning() {
return prefetchRunning.get();
}
// double buffer - double cache size
private int calcCacheCapacity() {
int capacity = Integer.MAX_VALUE;
if(caching > 0 && caching < (Integer.MAX_VALUE /2)) {
capacity = caching * 2 + 1;
}
if(capacity == Integer.MAX_VALUE){
if(maxScannerResultSize != Integer.MAX_VALUE) {
capacity = (int) (maxScannerResultSize / ESTIMATED_SINGLE_RESULT_SIZE);
}
else {
capacity = DEFAULT_QUEUE_CAPACITY;
}
}
return capacity;
}
private boolean prefetchCondition() {
return
(getCacheCount() < getCountThreshold()) &&
(maxScannerResultSize == Long.MAX_VALUE ||
getCacheSizeInBytes() < getSizeThreshold()) ;
}
private int getCountThreshold() {
return cacheCapacity / 2 ;
}
private long getSizeThreshold() {
return maxScannerResultSize / 2 ;
}
private long getCacheSizeInBytes() {
return cacheSizeInBytes.get();
}
private class PrefetchRunnable implements Runnable {
@Override
public void run() {
try {
loadCache();
} catch (Exception e) {
exceptionsQueue.add(e);
} finally {
prefetchRunning.set(false);
if(closed) {
if (closingThreadId.compareAndSet(NO_THREAD, Thread.currentThread().getId())) {
// close was waiting for the prefetch to end
close();
}
}
}
}
}
}

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@ -17,14 +17,7 @@
*/
package org.apache.hadoop.hbase.client;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import com.google.common.annotations.VisibleForTesting;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
@ -45,7 +38,14 @@ import org.apache.hadoop.hbase.protobuf.generated.MapReduceProtos;
import org.apache.hadoop.hbase.regionserver.RegionServerStoppedException;
import org.apache.hadoop.hbase.util.Bytes;
import com.google.common.annotations.VisibleForTesting;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.ExecutorService;
/**
* Implements the scanner interface for the HBase client.
@ -53,7 +53,7 @@ import com.google.common.annotations.VisibleForTesting;
* through them all.
*/
@InterfaceAudience.Private
public class ClientScanner extends AbstractClientScanner {
public abstract class ClientScanner extends AbstractClientScanner {
private static final Log LOG = LogFactory.getLog(ClientScanner.class);
// A byte array in which all elements are the max byte, and it is used to
// construct closest front row
@ -64,7 +64,7 @@ public class ClientScanner extends AbstractClientScanner {
// wonky: e.g. if it splits on us.
protected HRegionInfo currentRegion = null;
protected ScannerCallableWithReplicas callable = null;
protected final LinkedList<Result> cache = new LinkedList<Result>();
protected Queue<Result> cache;
/**
* A list of partial results that have been returned from the server. This list should only
* contain results if this scanner does not have enough partial results to form the complete
@ -151,9 +151,12 @@ public class ClientScanner extends AbstractClientScanner {
this.rpcControllerFactory = controllerFactory;
this.conf = conf;
initCache();
initializeScannerInConstruction();
}
protected abstract void initCache();
protected void initializeScannerInConstruction() throws IOException{
// initialize the scanner
nextScanner(this.caching, false);
@ -342,8 +345,11 @@ public class ClientScanner extends AbstractClientScanner {
scanMetricsPublished = true;
}
@Override
public Result next() throws IOException {
protected void initSyncCache() {
cache = new LinkedList<Result>();
}
protected Result nextWithSyncCache() throws IOException {
// If the scanner is closed and there's nothing left in the cache, next is a no-op.
if (cache.size() == 0 && this.closed) {
return null;
@ -370,6 +376,8 @@ public class ClientScanner extends AbstractClientScanner {
* Contact the servers to load more {@link Result}s in the cache.
*/
protected void loadCache() throws IOException {
// check if scanner was closed during previous prefetch
if (closed) return;
Result[] values = null;
long remainingResultSize = maxScannerResultSize;
int countdown = this.caching;
@ -482,11 +490,10 @@ public class ClientScanner extends AbstractClientScanner {
if (!resultsToAddToCache.isEmpty()) {
for (Result rs : resultsToAddToCache) {
cache.add(rs);
// We don't make Iterator here
for (Cell cell : rs.rawCells()) {
remainingResultSize -= CellUtil.estimatedHeapSizeOf(cell);
}
long estimatedHeapSizeOfResult = calcEstimatedSize(rs);
countdown--;
remainingResultSize -= estimatedHeapSizeOfResult;
addEstimatedSize(estimatedHeapSizeOfResult);
this.lastResult = rs;
}
}
@ -532,6 +539,24 @@ public class ClientScanner extends AbstractClientScanner {
return remainingResultSize > 0 && remainingRows > 0 && !regionHasMoreResults;
}
protected long calcEstimatedSize(Result rs) {
long estimatedHeapSizeOfResult = 0;
// We don't make Iterator here
for (Cell cell : rs.rawCells()) {
estimatedHeapSizeOfResult += CellUtil.estimatedHeapSizeOf(cell);
}
return estimatedHeapSizeOfResult;
}
protected void addEstimatedSize(long estimatedHeapSizeOfResult) {
return;
}
@VisibleForTesting
public int getCacheCount() {
return cache != null ? cache.size() : 0;
}
/**
* This method ensures all of our book keeping regarding partial results is kept up to date. This
* method should be called once we know that the results we received back from the RPC request do

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@ -0,0 +1,54 @@
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* 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 KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.client;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
import java.io.IOException;
import java.util.LinkedList;
import java.util.concurrent.ExecutorService;
/**
* ClientSimpleScanner implements a sync scanner behaviour.
* The cache is a simple list.
* The prefetch is invoked only when the application finished processing the entire cache.
*/
@InterfaceAudience.Private
public class ClientSimpleScanner extends ClientScanner {
public ClientSimpleScanner(Configuration configuration, Scan scan, TableName name,
ClusterConnection connection, RpcRetryingCallerFactory rpcCallerFactory,
RpcControllerFactory rpcControllerFactory, ExecutorService pool,
int replicaCallTimeoutMicroSecondScan) throws IOException {
super(configuration, scan, name, connection, rpcCallerFactory, rpcControllerFactory, pool,
replicaCallTimeoutMicroSecondScan);
}
@Override
protected void initCache() {
initSyncCache();
}
@Override
public Result next() throws IOException {
return nextWithSyncCache();
}
}

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@ -18,10 +18,8 @@
*/
package org.apache.hadoop.hbase.client;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.concurrent.ExecutorService;
import com.google.common.annotations.VisibleForTesting;
import com.google.protobuf.ServiceException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
@ -39,8 +37,9 @@ import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanResponse;
import org.apache.hadoop.hbase.util.Bytes;
import com.google.common.annotations.VisibleForTesting;
import com.google.protobuf.ServiceException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.concurrent.ExecutorService;
/**
* Client scanner for small scan. Generally, only one RPC is called to fetch the
@ -50,7 +49,7 @@ import com.google.protobuf.ServiceException;
* For small scan, it will get better performance than {@link ClientScanner}
*/
@InterfaceAudience.Private
public class ClientSmallScanner extends ClientScanner {
public class ClientSmallScanner extends ClientSimpleScanner {
private static final Log LOG = LogFactory.getLog(ClientSmallScanner.class);
private ScannerCallableWithReplicas smallScanCallable = null;
private SmallScannerCallableFactory callableFactory;

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@ -620,6 +620,11 @@ public class HTable implements HTableInterface {
scan.setMaxResultSize(scannerMaxResultSize);
}
Boolean async = scan.isAsyncPrefetch();
if (async == null) {
async = tableConfiguration.isClientScannerAsyncPrefetch();
}
if (scan.isReversed()) {
if (scan.isSmall()) {
return new ClientSmallReversedScanner(getConfiguration(), scan, getName(),
@ -637,9 +642,15 @@ public class HTable implements HTableInterface {
this.connection, this.rpcCallerFactory, this.rpcControllerFactory,
pool, tableConfiguration.getReplicaCallTimeoutMicroSecondScan());
} else {
return new ClientScanner(getConfiguration(), scan, getName(), this.connection,
this.rpcCallerFactory, this.rpcControllerFactory,
pool, tableConfiguration.getReplicaCallTimeoutMicroSecondScan());
if (async) {
return new ClientAsyncPrefetchScanner(getConfiguration(), scan, getName(), this.connection,
this.rpcCallerFactory, this.rpcControllerFactory,
pool, tableConfiguration.getReplicaCallTimeoutMicroSecondScan());
} else {
return new ClientSimpleScanner(getConfiguration(), scan, getName(), this.connection,
this.rpcCallerFactory, this.rpcControllerFactory,
pool, tableConfiguration.getReplicaCallTimeoutMicroSecondScan());
}
}
}

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@ -35,7 +35,7 @@ import org.apache.hadoop.hbase.util.ExceptionUtil;
* A reversed client scanner which support backward scanning
*/
@InterfaceAudience.Private
public class ReversedClientScanner extends ClientScanner {
public class ReversedClientScanner extends ClientSimpleScanner {
private static final Log LOG = LogFactory.getLog(ReversedClientScanner.class);
/**

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@ -145,8 +145,23 @@ public class Scan extends Query {
private Map<byte [], NavigableSet<byte []>> familyMap =
new TreeMap<byte [], NavigableSet<byte []>>(Bytes.BYTES_COMPARATOR);
private Boolean loadColumnFamiliesOnDemand = null;
private Boolean asyncPrefetch = null;
/**
* Parameter name for client scanner sync/async prefetch toggle.
* When using async scanner, prefetching data from the server is done at the background.
* The parameter currently won't have any effect in the case that the user has set
* Scan#setSmall or Scan#setReversed
*/
public static final String HBASE_CLIENT_SCANNER_ASYNC_PREFETCH =
"hbase.client.scanner.async.prefetch";
/**
* Default value of {@link #HBASE_CLIENT_SCANNER_ASYNC_PREFETCH}.
*/
public static final boolean DEFAULT_HBASE_CLIENT_SCANNER_ASYNC_PREFETCH = false;
/**
* Set it true for small scan to get better performance
*
* Small scan should use pread and big scan can use seek + read
@ -255,6 +270,7 @@ public class Scan extends Query {
this.tr = get.getTimeRange();
this.familyMap = get.getFamilyMap();
this.getScan = true;
this.asyncPrefetch = false;
this.consistency = get.getConsistency();
for (Map.Entry<String, byte[]> attr : get.getAttributesMap().entrySet()) {
setAttribute(attr.getKey(), attr.getValue());
@ -971,4 +987,16 @@ public class Scan extends Query {
if (bytes == null) return null;
return ProtobufUtil.toScanMetrics(bytes);
}
public Boolean isAsyncPrefetch() {
return asyncPrefetch;
}
public Scan setAsyncPrefetch(boolean asyncPrefetch) {
this.asyncPrefetch = asyncPrefetch;
return this;
}
}

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@ -43,7 +43,10 @@ public class TableConfiguration {
private final int retries;
private final int maxKeyValueSize;
/**
// toggle for async/sync prefetch
private final boolean clientScannerAsyncPrefetch;
/**
* Constructor
* @param conf Configuration object
*/
@ -73,6 +76,9 @@ public class TableConfiguration {
this.retries = conf.getInt(
HConstants.HBASE_CLIENT_RETRIES_NUMBER, HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER);
this.clientScannerAsyncPrefetch = conf.getBoolean(
Scan.HBASE_CLIENT_SCANNER_ASYNC_PREFETCH, Scan.DEFAULT_HBASE_CLIENT_SCANNER_ASYNC_PREFETCH);
this.maxKeyValueSize = conf.getInt(MAX_KEYVALUE_SIZE_KEY, MAX_KEYVALUE_SIZE_DEFAULT);
}
@ -91,6 +97,7 @@ public class TableConfiguration {
this.primaryCallTimeoutMicroSecond = 10000;
this.replicaCallTimeoutMicroSecondScan = 1000000;
this.retries = HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER;
this.clientScannerAsyncPrefetch = Scan.DEFAULT_HBASE_CLIENT_SCANNER_ASYNC_PREFETCH;
this.maxKeyValueSize = MAX_KEYVALUE_SIZE_DEFAULT;
}
@ -129,4 +136,9 @@ public class TableConfiguration {
public long getScannerMaxResultSize() {
return scannerMaxResultSize;
}
public boolean isClientScannerAsyncPrefetch() {
return clientScannerAsyncPrefetch;
}
}

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@ -23,6 +23,7 @@ import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import java.io.IOException;
import java.util.LinkedList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
@ -121,6 +122,15 @@ public class TestClientScanner {
public void setRpcFinished(boolean rpcFinished) {
this.rpcFinished = rpcFinished;
}
@Override
protected void initCache() {
initSyncCache();
}
@Override public Result next() throws IOException {
return nextWithSyncCache();
}
}
@Test

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@ -17,23 +17,9 @@
*/
package org.apache.hadoop.hbase.client;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.KeyValue.Type;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.ClientSmallScanner.SmallScannerCallableFactory;
import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
@ -46,6 +32,16 @@ import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.Queue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
/**
* Test the ClientSmallReversedScanner.
*/
@ -178,7 +174,7 @@ public class TestClientSmallReversedScanner {
csrs.loadCache();
List<Result> results = csrs.cache;
Queue<Result> results = csrs.cache;
Iterator<Result> iter = results.iterator();
assertEquals(3, results.size());
for (int i = 3; i >= 1 && iter.hasNext(); i--) {
@ -248,7 +244,7 @@ public class TestClientSmallReversedScanner {
csrs.loadCache();
List<Result> results = csrs.cache;
Queue<Result> results = csrs.cache;
Iterator<Result> iter = results.iterator();
assertEquals(2, results.size());
for (int i = 3; i >= 2 && iter.hasNext(); i--) {
@ -264,7 +260,7 @@ public class TestClientSmallReversedScanner {
csrs.loadCache();
assertEquals(1, results.size());
Result result = results.get(0);
Result result = results.peek();
assertEquals("row1", new String(result.getRow(), StandardCharsets.UTF_8));
assertEquals(1, result.getMap().size());

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@ -17,22 +17,9 @@
*/
package org.apache.hadoop.hbase.client;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.KeyValue.Type;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.ClientSmallScanner.SmallScannerCallableFactory;
import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
@ -45,6 +32,15 @@ import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Queue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
/**
* Test the ClientSmallScanner.
*/
@ -176,10 +172,10 @@ public class TestClientSmallScanner {
css.loadCache();
List<Result> results = css.cache;
Queue<Result> results = css.cache;
assertEquals(3, results.size());
for (int i = 1; i <= 3; i++) {
Result result = results.get(i - 1);
Result result = results.poll();
byte[] row = result.getRow();
assertEquals("row" + i, new String(row, StandardCharsets.UTF_8));
assertEquals(1, result.getMap().size());
@ -243,10 +239,10 @@ public class TestClientSmallScanner {
css.loadCache();
List<Result> results = css.cache;
Queue<Result> results = css.cache;
assertEquals(2, results.size());
for (int i = 1; i <= 2; i++) {
Result result = results.get(i - 1);
Result result = results.poll();
byte[] row = result.getRow();
assertEquals("row" + i, new String(row, StandardCharsets.UTF_8));
assertEquals(1, result.getMap().size());
@ -258,7 +254,7 @@ public class TestClientSmallScanner {
css.loadCache();
assertEquals(1, results.size());
Result result = results.get(0);
Result result = results.peek();
assertEquals("row3", new String(result.getRow(), StandardCharsets.UTF_8));
assertEquals(1, result.getMap().size());
assertTrue(css.closed);

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@ -642,6 +642,55 @@ public class TestScannersFromClientSide {
verifyResult(result, kvListExp, toLog, "Testing scan on re-opened region");
}
/**
* Test from client side for async scan
*
* @throws Exception
*/
@Test
public void testAsyncScanner() throws Exception {
byte [] TABLE = Bytes.toBytes("testAsyncScan");
byte [][] ROWS = HTestConst.makeNAscii(ROW, 2);
byte [][] FAMILIES = HTestConst.makeNAscii(FAMILY, 3);
byte [][] QUALIFIERS = HTestConst.makeNAscii(QUALIFIER, 10);
HTable ht = TEST_UTIL.createTable(TABLE, FAMILIES);
Put put;
Scan scan;
Result result;
boolean toLog = true;
List<Cell> kvListExp, kvListScan;
kvListExp = new ArrayList<Cell>();
for (int r=0; r < ROWS.length; r++) {
put = new Put(ROWS[r]);
for (int c=0; c < FAMILIES.length; c++) {
for (int q=0; q < QUALIFIERS.length; q++) {
KeyValue kv = new KeyValue(ROWS[r], FAMILIES[c], QUALIFIERS[q], 1, VALUE);
put.add(kv);
kvListExp.add(kv);
}
}
ht.put(put);
}
scan = new Scan();
scan.setAsyncPrefetch(true);
ResultScanner scanner = ht.getScanner(scan);
kvListScan = new ArrayList<Cell>();
while ((result = scanner.next()) != null) {
for (Cell kv : result.listCells()) {
kvListScan.add(kv);
}
}
result = Result.create(kvListScan);
assertTrue("Not instance of async scanner",scanner instanceof ClientAsyncPrefetchScanner);
verifyResult(result, kvListExp, toLog, "Testing async scan");
}
static void verifyResult(Result result, List<Cell> expKvList, boolean toLog,
String msg) {