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Client interface into HPCC Systems' Distributed File System.
/*******************************************************************************
* HPCC SYSTEMS software Copyright (C) 2021 HPCC Systems®.
*
* 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, 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.hpccsystems.dfs.client;
import org.hpccsystems.commons.ecl.FieldDef;
import org.hpccsystems.commons.errors.HpccFileException;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
/**
* File reader that allows random access of records in an HPCC Systems file part.
*
* A connection to the remote dafilesrv will be opened upon initialization and remain open to process fetch requests in batches.
*/
public class HpccRandomAccessFileReader implements Iterator
{
private static final Logger log = LogManager.getLogger(HpccRandomAccessFileReader.class);
private FieldDef originalRecordDef = null;
private DataPartition dataPartition = null;
private RowServiceInputStream inputStream = null;
private BinaryRecordReader binaryRecordReader;
private IRecordBuilder recordBuilder = null;
private ArrayList requestedRecordOffsets = new ArrayList();
private ArrayList queuedRecordOffsets = new ArrayList();
private Thread fetchRequestThread = null;
/**
* A random access file reader that reads the part identified by the HpccPart object using the record definition provided.
*
* @param dp
* the part of the file, name and location
* @param originalRD
* the record defintion for the dataset
* @param recBuilder
* the IRecordBuilder used to construct records
* @param connectTimeout
* the connection timeout in seconds, -1 and/or 0 for default
* @throws Exception
* general exception
*/
public HpccRandomAccessFileReader(DataPartition dp, FieldDef originalRD, IRecordBuilder recBuilder, int connectTimeout) throws Exception
{
this.originalRecordDef = originalRD;
if (this.originalRecordDef == null)
{
throw new Exception("HpccRemoteFileReader: Original record definition is null.");
}
if (connectTimeout < 1)
{
connectTimeout = RowServiceInputStream.DEFAULT_CONNECT_TIMEOUT_MILIS;
}
this.dataPartition = dp;
this.recordBuilder = recBuilder;
FieldDef projectedRecordDefinition = recBuilder.getRecordDefinition();
if (projectedRecordDefinition == null)
{
throw new Exception("IRecordBuilder does not have a valid record definition.");
}
boolean isFetching = true;
boolean createPrefetchThread = false;
this.inputStream = new RowServiceInputStream(this.dataPartition, this.originalRecordDef, projectedRecordDefinition, connectTimeout,
-1, createPrefetchThread, -1, null, isFetching);
this.binaryRecordReader = new BinaryRecordReader(this.inputStream);
this.binaryRecordReader.initialize(this.recordBuilder);
if (dp.getFileType() == DataPartition.FileType.INDEX)
{
this.binaryRecordReader.setIsIndex(true);
}
}
/**
* Add a list of records to be fetched via hasNext() / next()
* @param recordOffsets
* the record offset
*/
public void addRecordRequests(List recordOffsets)
{
queuedRecordOffsets.addAll(recordOffsets);
}
public int getRemoteReadMessageCount()
{
int count = 0;
if (binaryRecordReader != null)
count = binaryRecordReader.getStreamMessageCount();
return count;
}
public String getRemoteReadMessages()
{
String report = "";
if (binaryRecordReader != null)
report = binaryRecordReader.getStreamMessages();
return report;
}
/**
* Is there more data
*
* @return true if there is a next record
*/
@Override
public boolean hasNext()
{
int numRemainingRecords = requestedRecordOffsets.size() + queuedRecordOffsets.size();
if (numRemainingRecords == 0)
{
return false;
}
return true;
}
/**
* Return next record, can return null if an invalid record offset was requested.
*
* @return the record
*/
@Override
public T next()
{
if (hasNext() == false)
{
String errorMessage = "No records remaining in request or no records have been requested.";
log.error(errorMessage);
throw new java.util.NoSuchElementException(errorMessage);
}
// If we have consumed all of the requested records make a new request based on the queued requests
if (requestedRecordOffsets.size() == 0)
{
requestedRecordOffsets.addAll(queuedRecordOffsets);
queuedRecordOffsets.clear();
Runnable fetchRequestTask = new Runnable()
{
RowServiceInputStream inputStream = HpccRandomAccessFileReader.this.inputStream;
public void run()
{
try
{
inputStream.startBlockingFetchRequest(requestedRecordOffsets);
}
catch(Exception e)
{
String errorMessage = "Error while performing block fetch request: " + e.getMessage();
log.error(errorMessage);
throw new java.util.NoSuchElementException(errorMessage);
}
}
};
fetchRequestThread = new Thread(fetchRequestTask);
fetchRequestThread.start();
}
Object rslt = null;
try
{
rslt = this.binaryRecordReader.getNext();
}
catch (HpccFileException e)
{
log.error("Read failure for " + this.dataPartition.toString() + " " + e.getMessage());
throw new java.util.NoSuchElementException("Fatal read error: " + e.getMessage());
}
this.requestedRecordOffsets.remove(0);
return (T) rslt;
}
/**
* Closes inputstream, reports summary of messages generated during read operation.
*
* @throws Exception
* the exception
*/
public void close() throws Exception
{
report();
this.inputStream.close();
}
public RowServiceInputStream getInputStream()
{
return this.inputStream;
}
public BinaryRecordReader getRecordReader()
{
return this.binaryRecordReader;
}
/**
* Reports summary of messages generated during read operation.
*
*/
public void report()
{
if (getRemoteReadMessageCount() > 0)
{
log.warn("DataPartition '" + this.dataPartition + "' read operation messages:\n");
log.warn(getRemoteReadMessages());
}
}
}