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/**
* 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 static org.apache.hadoop.hbase.client.ConnectionUtils.incRPCCallsMetrics;
import static org.apache.hadoop.hbase.client.ConnectionUtils.incRPCRetriesMetrics;
import static org.apache.hadoop.hbase.client.ConnectionUtils.isRemote;
import static org.apache.hadoop.hbase.client.ConnectionUtils.updateResultsMetrics;
import static org.apache.hadoop.hbase.client.ConnectionUtils.updateServerSideMetrics;
import java.io.IOException;
import java.io.InterruptedIOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.DoNotRetryIOException;
import org.apache.hadoop.hbase.HBaseIOException;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.NotServingRegionException;
import org.apache.hadoop.hbase.RegionLocations;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.UnknownScannerException;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
import org.apache.hadoop.hbase.exceptions.ScannerResetException;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
import org.apache.hadoop.hbase.regionserver.RegionServerStoppedException;
import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.shaded.protobuf.RequestConverter;
import org.apache.hadoop.hbase.shaded.protobuf.ResponseConverter;
import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanRequest;
import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanResponse;
/**
* Scanner operations such as create, next, etc.
* Used by {@link ResultScanner}s made by {@link Table}. Passed to a retrying caller such as
* {@link RpcRetryingCaller} so fails are retried.
*/
@InterfaceAudience.Private
public class ScannerCallable extends ClientServiceCallable {
public static final String LOG_SCANNER_LATENCY_CUTOFF
= "hbase.client.log.scanner.latency.cutoff";
public static final String LOG_SCANNER_ACTIVITY = "hbase.client.log.scanner.activity";
// Keeping LOG public as it is being used in TestScannerHeartbeatMessages
public static final Logger LOG = LoggerFactory.getLogger(ScannerCallable.class);
protected long scannerId = -1L;
protected boolean instantiated = false;
protected boolean closed = false;
protected boolean renew = false;
protected final Scan scan;
private int caching = 1;
protected ScanMetrics scanMetrics;
private boolean logScannerActivity = false;
private int logCutOffLatency = 1000;
protected final int id;
enum MoreResults {
YES, NO, UNKNOWN
}
private MoreResults moreResultsInRegion;
private MoreResults moreResultsForScan;
/**
* Saves whether or not the most recent response from the server was a heartbeat message.
* Heartbeat messages are identified by the flag {@link ScanResponse#getHeartbeatMessage()}
*/
protected boolean heartbeatMessage = false;
protected Cursor cursor;
// indicate if it is a remote server call
protected boolean isRegionServerRemote = true;
private long nextCallSeq = 0;
protected final RpcControllerFactory rpcControllerFactory;
/**
* @param connection which connection
* @param tableName table callable is on
* @param scan the scan to execute
* @param scanMetrics the ScanMetrics to used, if it is null, ScannerCallable won't collect
* metrics
* @param rpcControllerFactory factory to use when creating
* {@link com.google.protobuf.RpcController}
*/
public ScannerCallable(ClusterConnection connection, TableName tableName, Scan scan,
ScanMetrics scanMetrics, RpcControllerFactory rpcControllerFactory) {
this(connection, tableName, scan, scanMetrics, rpcControllerFactory, 0);
}
/**
*
* @param connection
* @param tableName
* @param scan
* @param scanMetrics
* @param id the replicaId
*/
public ScannerCallable(ClusterConnection connection, TableName tableName, Scan scan,
ScanMetrics scanMetrics, RpcControllerFactory rpcControllerFactory, int id) {
super(connection, tableName, scan.getStartRow(), rpcControllerFactory.newController(), scan.getPriority());
this.id = id;
this.scan = scan;
this.scanMetrics = scanMetrics;
Configuration conf = connection.getConfiguration();
logScannerActivity = conf.getBoolean(LOG_SCANNER_ACTIVITY, false);
logCutOffLatency = conf.getInt(LOG_SCANNER_LATENCY_CUTOFF, 1000);
this.rpcControllerFactory = rpcControllerFactory;
}
/**
* @param reload force reload of server location
* @throws IOException
*/
@Override
public void prepare(boolean reload) throws IOException {
if (Thread.interrupted()) {
throw new InterruptedIOException();
}
RegionLocations rl = RpcRetryingCallerWithReadReplicas.getRegionLocations(!reload,
id, getConnection(), getTableName(), getRow());
location = id < rl.size() ? rl.getRegionLocation(id) : null;
if (location == null || location.getServerName() == null) {
// With this exception, there will be a retry. The location can be null for a replica
// when the table is created or after a split.
throw new HBaseIOException("There is no location for replica id #" + id);
}
ServerName dest = location.getServerName();
setStub(super.getConnection().getClient(dest));
if (!instantiated || reload) {
checkIfRegionServerIsRemote();
instantiated = true;
}
cursor = null;
// check how often we retry.
if (reload) {
incRPCRetriesMetrics(scanMetrics, isRegionServerRemote);
}
}
/**
* compare the local machine hostname with region server's hostname to decide if hbase client
* connects to a remote region server
*/
protected void checkIfRegionServerIsRemote() {
isRegionServerRemote = isRemote(getLocation().getHostname());
}
private ScanResponse next() throws IOException {
// Reset the heartbeat flag prior to each RPC in case an exception is thrown by the server
setHeartbeatMessage(false);
incRPCCallsMetrics(scanMetrics, isRegionServerRemote);
ScanRequest request = RequestConverter.buildScanRequest(scannerId, caching, false, nextCallSeq,
this.scanMetrics != null, renew, scan.getLimit());
try {
ScanResponse response = getStub().scan(getRpcController(), request);
nextCallSeq++;
return response;
} catch (Exception e) {
IOException ioe = ProtobufUtil.handleRemoteException(e);
if (logScannerActivity) {
LOG.info(
"Got exception making request " + ProtobufUtil.toText(request) + " to " + getLocation(),
e);
}
if (logScannerActivity) {
if (ioe instanceof UnknownScannerException) {
try {
HRegionLocation location =
getConnection().relocateRegion(getTableName(), scan.getStartRow());
LOG.info("Scanner=" + scannerId + " expired, current region location is "
+ location.toString());
} catch (Throwable t) {
LOG.info("Failed to relocate region", t);
}
} else if (ioe instanceof ScannerResetException) {
LOG.info("Scanner=" + scannerId + " has received an exception, and the server "
+ "asked us to reset the scanner state.",
ioe);
}
}
// The below convertion of exceptions into DoNotRetryExceptions is a little strange.
// Why not just have these exceptions implment DNRIOE you ask? Well, usually we want
// ServerCallable#withRetries to just retry when it gets these exceptions. In here in
// a scan when doing a next in particular, we want to break out and get the scanner to
// reset itself up again. Throwing a DNRIOE is how we signal this to happen (its ugly,
// yeah and hard to follow and in need of a refactor).
if (ioe instanceof NotServingRegionException) {
// Throw a DNRE so that we break out of cycle of calling NSRE
// when what we need is to open scanner against new location.
// Attach NSRE to signal client that it needs to re-setup scanner.
if (this.scanMetrics != null) {
this.scanMetrics.countOfNSRE.incrementAndGet();
}
throw new DoNotRetryIOException("Resetting the scanner -- see exception cause", ioe);
} else if (ioe instanceof RegionServerStoppedException) {
// Throw a DNRE so that we break out of cycle of the retries and instead go and
// open scanner against new location.
throw new DoNotRetryIOException("Resetting the scanner -- see exception cause", ioe);
} else {
// The outer layers will retry
throw ioe;
}
}
}
private void setAlreadyClosed() {
this.scannerId = -1L;
this.closed = true;
}
@Override
protected Result[] rpcCall() throws Exception {
if (Thread.interrupted()) {
throw new InterruptedIOException();
}
if (closed) {
close();
return null;
}
ScanResponse response;
if (this.scannerId == -1L) {
response = openScanner();
} else {
response = next();
}
long timestamp = System.currentTimeMillis();
boolean isHeartBeat = response.hasHeartbeatMessage() && response.getHeartbeatMessage();
setHeartbeatMessage(isHeartBeat);
if (isHeartBeat && scan.isNeedCursorResult() && response.hasCursor()) {
cursor = ProtobufUtil.toCursor(response.getCursor());
}
Result[] rrs = ResponseConverter.getResults(getRpcControllerCellScanner(), response);
if (logScannerActivity) {
long now = System.currentTimeMillis();
if (now - timestamp > logCutOffLatency) {
int rows = rrs == null ? 0 : rrs.length;
LOG.info("Took " + (now - timestamp) + "ms to fetch " + rows + " rows from scanner="
+ scannerId);
}
}
updateServerSideMetrics(scanMetrics, response);
// moreResults is only used for the case where a filter exhausts all elements
if (response.hasMoreResults()) {
if (response.getMoreResults()) {
setMoreResultsForScan(MoreResults.YES);
} else {
setMoreResultsForScan(MoreResults.NO);
setAlreadyClosed();
}
} else {
setMoreResultsForScan(MoreResults.UNKNOWN);
}
if (response.hasMoreResultsInRegion()) {
if (response.getMoreResultsInRegion()) {
setMoreResultsInRegion(MoreResults.YES);
} else {
setMoreResultsInRegion(MoreResults.NO);
setAlreadyClosed();
}
} else {
setMoreResultsInRegion(MoreResults.UNKNOWN);
}
updateResultsMetrics(scanMetrics, rrs, isRegionServerRemote);
return rrs;
}
/**
* @return true when the most recent RPC response indicated that the response was a heartbeat
* message. Heartbeat messages are sent back from the server when the processing of the
* scan request exceeds a certain time threshold. Heartbeats allow the server to avoid
* timeouts during long running scan operations.
*/
boolean isHeartbeatMessage() {
return heartbeatMessage;
}
public Cursor getCursor() {
return cursor;
}
private void setHeartbeatMessage(boolean heartbeatMessage) {
this.heartbeatMessage = heartbeatMessage;
}
private void close() {
if (this.scannerId == -1L) {
return;
}
try {
incRPCCallsMetrics(scanMetrics, isRegionServerRemote);
ScanRequest request =
RequestConverter.buildScanRequest(this.scannerId, 0, true, this.scanMetrics != null);
try {
getStub().scan(getRpcController(), request);
} catch (Exception e) {
throw ProtobufUtil.handleRemoteException(e);
}
} catch (IOException e) {
TableName table = getTableName();
String tableDetails = (table == null) ? "" : (" on table: " + table.getNameAsString());
LOG.warn("Ignore, probably already closed. Current scan: " + getScan().toString()
+ tableDetails, e);
}
this.scannerId = -1L;
}
private ScanResponse openScanner() throws IOException {
incRPCCallsMetrics(scanMetrics, isRegionServerRemote);
ScanRequest request = RequestConverter.buildScanRequest(
getLocation().getRegionInfo().getRegionName(), this.scan, this.caching, false);
try {
ScanResponse response = getStub().scan(getRpcController(), request);
long id = response.getScannerId();
if (logScannerActivity) {
LOG.info("Open scanner=" + id + " for scan=" + scan.toString()
+ " on region " + getLocation().toString());
}
if (response.hasMvccReadPoint()) {
this.scan.setMvccReadPoint(response.getMvccReadPoint());
}
this.scannerId = id;
return response;
} catch (Exception e) {
throw ProtobufUtil.handleRemoteException(e);
}
}
protected Scan getScan() {
return scan;
}
/**
* Call this when the next invocation of call should close the scanner
*/
public void setClose() {
this.closed = true;
}
/**
* Indicate whether we make a call only to renew the lease, but without affected the scanner in
* any other way.
* @param val true if only the lease should be renewed
*/
public void setRenew(boolean val) {
this.renew = val;
}
/**
* @return the HRegionInfo for the current region
*/
@Override
public HRegionInfo getHRegionInfo() {
if (!instantiated) {
return null;
}
return getLocation().getRegionInfo();
}
/**
* Get the number of rows that will be fetched on next
* @return the number of rows for caching
*/
public int getCaching() {
return caching;
}
/**
* Set the number of rows that will be fetched on next
* @param caching the number of rows for caching
*/
public void setCaching(int caching) {
this.caching = caching;
}
public ScannerCallable getScannerCallableForReplica(int id) {
ScannerCallable s = new ScannerCallable(this.getConnection(), getTableName(),
this.getScan(), this.scanMetrics, this.rpcControllerFactory, id);
s.setCaching(this.caching);
return s;
}
/**
* Should the client attempt to fetch more results from this region
*/
MoreResults moreResultsInRegion() {
return moreResultsInRegion;
}
void setMoreResultsInRegion(MoreResults moreResults) {
this.moreResultsInRegion = moreResults;
}
/**
* Should the client attempt to fetch more results for the whole scan.
*/
MoreResults moreResultsForScan() {
return moreResultsForScan;
}
void setMoreResultsForScan(MoreResults moreResults) {
this.moreResultsForScan = moreResults;
}
}
