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Add peer download fallback to PredownloadScheduler #18641

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Add peer download fallback to PredownloadScheduler #18641

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84 changes: 65 additions & 19 deletions pinot-server/src/main/java/org/apache/pinot/server/predownload/PredownloadScheduler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,9 @@
import com.google.common.annotations.VisibleForTesting;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
Expand Down Expand Up @@ -72,6 +74,8 @@ public class PredownloadScheduler {
@VisibleForTesting
Set<String> _failedSegments;
private PredownloadMetrics _predownloadMetrics;
private boolean _peerDownloadEnabled;
private String _peerDownloadScheme;
private int _numOfSkippedSegments;
private int _numOfUnableToDownloadSegments;
private int _numOfDownloadSegments;
Expand All @@ -80,7 +84,7 @@ public class PredownloadScheduler {
private List<PredownloadSegmentInfo> _predownloadSegmentInfoList;
private Map<String, PredownloadTableInfo> _tableInfoMap;

public PredownloadScheduler(PropertiesConfiguration properties)
public PredownloadScheduler(PropertiesConfiguration properties, boolean peerDownloadEnabled)
throws Exception {
_properties = properties;
_clusterName = properties.getString(CommonConstants.Helix.CONFIG_OF_CLUSTER_NAME);
Expand All @@ -107,6 +111,11 @@ public PredownloadScheduler(PropertiesConfiguration properties)
_failedSegments = ConcurrentHashMap.newKeySet();
_executor = Executors.newFixedThreadPool(predownloadParallelism);
LOGGER.info("Created thread pool with num of threads: {}", predownloadParallelism);

_peerDownloadEnabled = peerDownloadEnabled;
_peerDownloadScheme = _instanceDataManagerConfig.getSegmentPeerDownloadScheme();
LOGGER.info("Peer download enabled: {}, scheme: {}", _peerDownloadEnabled, _peerDownloadScheme);

_numOfSkippedSegments = 0;
_numOfDownloadSegments = 0;
}
Expand Down Expand Up @@ -301,23 +310,15 @@ void downloadSegment(PredownloadSegmentInfo predownloadSegmentInfo)
throws Exception {
try {
long startTime = System.currentTimeMillis();
File tempRootDir = getTmpSegmentDataDir(predownloadSegmentInfo);
if (_instanceDataManagerConfig.isStreamSegmentDownloadUntar()
&& predownloadSegmentInfo.getCrypterName() == null) {
try {
// TODO: increase rate limit here
File untaredSegDir = downloadAndStreamUntarWithRateLimit(predownloadSegmentInfo, tempRootDir,
_instanceDataManagerConfig.getStreamSegmentDownloadUntarRateLimit());
moveSegment(predownloadSegmentInfo, untaredSegDir);
} finally {
FileUtils.deleteQuietly(tempRootDir);
}
} else {
try {
File tarFile = downloadAndDecrypt(predownloadSegmentInfo, tempRootDir);
untarAndMoveSegment(predownloadSegmentInfo, tarFile, tempRootDir);
} finally {
FileUtils.deleteQuietly(tempRootDir);
try {
downloadFromDeepStore(predownloadSegmentInfo);
} catch (Exception e) {
if (_peerDownloadEnabled && _peerDownloadScheme != null) {
LOGGER.warn("Deep store download failed for segment: {} of table: {}, falling back to peer download",
predownloadSegmentInfo.getSegmentName(), predownloadSegmentInfo.getTableNameWithType(), e);
downloadFromPeers(predownloadSegmentInfo);
} else {
throw e;
}
}
_failedSegments.remove(predownloadSegmentInfo.getSegmentName());
Expand All @@ -336,6 +337,52 @@ void downloadSegment(PredownloadSegmentInfo predownloadSegmentInfo)
}
}

private void downloadFromDeepStore(PredownloadSegmentInfo predownloadSegmentInfo)
throws Exception {
File tempRootDir = getTmpSegmentDataDir(predownloadSegmentInfo);
if (_instanceDataManagerConfig.isStreamSegmentDownloadUntar()
&& predownloadSegmentInfo.getCrypterName() == null) {
try {
File untaredSegDir = downloadAndStreamUntarWithRateLimit(predownloadSegmentInfo, tempRootDir,
_instanceDataManagerConfig.getStreamSegmentDownloadUntarRateLimit());
moveSegment(predownloadSegmentInfo, untaredSegDir);
} finally {
FileUtils.deleteQuietly(tempRootDir);
}
} else {
try {
File tarFile = downloadAndDecrypt(predownloadSegmentInfo, tempRootDir);
untarAndMoveSegment(predownloadSegmentInfo, tarFile, tempRootDir);
} finally {
FileUtils.deleteQuietly(tempRootDir);
}
}
}

private void downloadFromPeers(PredownloadSegmentInfo predownloadSegmentInfo)
throws Exception {
String segmentName = predownloadSegmentInfo.getSegmentName();
String tableNameWithType = predownloadSegmentInfo.getTableNameWithType();
LOGGER.info("Downloading segment: {} of table: {} from peers using scheme: {}", segmentName, tableNameWithType,
_peerDownloadScheme);
File tempRootDir = getTmpSegmentDataDir(predownloadSegmentInfo);
try {
File segmentTarFile = new File(tempRootDir, segmentName + TarCompressionUtils.TAR_GZ_FILE_EXTENSION);
SegmentFetcherFactory.fetchAndDecryptSegmentToLocal(segmentName, _peerDownloadScheme, () -> {
List<URI> peerURIs =
_predownloadZkClient.getPeerServerURIs(_predownloadZkClient.getDataAccessor(), tableNameWithType,
segmentName, _peerDownloadScheme);
Collections.shuffle(peerURIs);
return peerURIs;
}, segmentTarFile, predownloadSegmentInfo.getCrypterName());
LOGGER.info("Downloaded segment: {} from peers to: {}, file length: {}", segmentName, segmentTarFile,
segmentTarFile.length());
untarAndMoveSegment(predownloadSegmentInfo, segmentTarFile, tempRootDir);
} finally {
FileUtils.deleteQuietly(tempRootDir);
}
}

private File getTmpSegmentDataDir(PredownloadSegmentInfo predownloadSegmentInfo)
throws Exception {
PredownloadTableInfo predownloadTableInfo = _tableInfoMap.get(predownloadSegmentInfo.getTableNameWithType());
Expand Down Expand Up @@ -395,7 +442,6 @@ File downloadAndDecrypt(PredownloadSegmentInfo predownloadSegmentInfo, File temp
} catch (AttemptsExceededException e) {
LOGGER.error("Attempts exceeded when downloading segment: {} for table: {} from: {} to: {}", segmentName,
tableNameWithType, uri, tarFile);
// TODO: add download from peer logic
throw e;
}
}
Expand Down
47 changes: 47 additions & 0 deletions pinot-server/src/main/java/org/apache/pinot/server/predownload/PredownloadZKClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
*/
package org.apache.pinot.server.predownload;

import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
Expand All @@ -28,6 +29,7 @@
import org.apache.helix.manager.zk.ZKHelixDataAccessor;
import org.apache.helix.manager.zk.ZkBaseDataAccessor;
import org.apache.helix.model.CurrentState;
import org.apache.helix.model.ExternalView;
import org.apache.helix.model.InstanceConfig;
import org.apache.helix.model.LiveInstance;
import org.apache.helix.store.zk.AutoFallbackPropertyStore;
Expand Down Expand Up @@ -147,6 +149,51 @@ public List<PredownloadSegmentInfo> getSegmentsOfInstance(HelixDataAccessor acce
return predownloadSegmentInfos;
}

/**
* Returns URIs of ONLINE peer servers hosting the given segment, excluding the current instance.
* Uses ExternalView to discover peers — mirrors PeerServerSegmentFinder without requiring HelixManager.
*/
public List<URI> getPeerServerURIs(HelixDataAccessor accessor, String tableNameWithType, String segmentName,
String downloadScheme) {
org.apache.helix.PropertyKey.Builder keyBuilder = accessor.keyBuilder();
ExternalView externalView = accessor.getProperty(keyBuilder.externalView(tableNameWithType));
if (externalView == null) {
LOGGER.warn("No external view for table: {} when finding peers for segment: {}", tableNameWithType, segmentName);
return new ArrayList<>();
}
Map<String, String> instanceStateMap = externalView.getStateMap(segmentName);
if (instanceStateMap == null) {
LOGGER.warn("Segment: {} not found in external view of table: {}", segmentName, tableNameWithType);
return new ArrayList<>();
}
String adminPortKey = CommonConstants.HTTP_PROTOCOL.equals(downloadScheme)
? CommonConstants.Helix.Instance.ADMIN_PORT_KEY
: CommonConstants.Helix.Instance.ADMIN_HTTPS_PORT_KEY;
List<URI> peerURIs = new ArrayList<>();
for (Map.Entry<String, String> entry : instanceStateMap.entrySet()) {
String instanceId = entry.getKey();
if (!CommonConstants.Helix.StateModel.SegmentStateModel.ONLINE.equals(entry.getValue())) {
continue;
}
InstanceConfig instanceConfig = accessor.getProperty(keyBuilder.instanceConfig(instanceId));
if (instanceConfig == null) {
LOGGER.warn("Failed to get instance config for peer: {}", instanceId);
continue;
}
String hostName = instanceConfig.getHostName();
int port = instanceConfig.getRecord()
.getIntField(adminPortKey, CommonConstants.Server.DEFAULT_ADMIN_API_PORT);
try {
peerURIs.add(new URI(
String.format("%s://%s:%d/segments/%s/%s",
downloadScheme, hostName, port, tableNameWithType, segmentName)));
} catch (Exception e) {
LOGGER.warn("Failed to construct peer URI for instance: {}", instanceId, e);
}
}
return peerURIs;
}

/**
* Update the segment deepstore metadata from ZK.
*
Expand Down
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