Page MenuHomec4science
Files F62271389

ArcRecordUtils.java
No OneTemporary
Actions

File Metadata

Created
Sun, May 12, 02:21

ArcRecordUtils.java
View Options

/*
* Warcbase: an open-source platform for managing web archives
*
* 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.warcbase.data;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.log4j.Logger;
import org.archive.io.arc.ARCReader;
import org.archive.io.arc.ARCReaderFactory;
import org.archive.io.arc.ARCRecord;
import org.archive.io.arc.ARCRecordMetaData;
/**
* Utilities for working with {@code ARCRecord}s (from archive.org APIs).
*/
public class ArcRecordUtils {
private static final Logger LOG = Logger.getLogger(ArcRecordUtils.class);
// TODO: these methods work fine, but there's a lot of unnecessary buffer copying, which is
// terrible from a performance perspective.
/**
* Converts raw bytes into an {@code ARCRecord}.
*
* @param bytes raw bytes
* @return parsed {@code ARCRecord}
* @throws IOException
*/
public static ARCRecord fromBytes(byte[] bytes) throws IOException {
ARCReader reader = (ARCReader) ARCReaderFactory.get("",
new BufferedInputStream(new ByteArrayInputStream(bytes)), false);
return (ARCRecord) reader.get();
}
public static byte[] toBytes(ARCRecord record) throws IOException {
ARCRecordMetaData meta = record.getMetaData();
String metaline = meta.getUrl() + " " + meta.getIp() + " " + meta.getDate() + " "
+ meta.getMimetype() + " " + (int) meta.getLength();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(baos);
dout.write(metaline.getBytes());
dout.write("\n".getBytes());
copyStream(record, (int) meta.getLength(), true, dout);
return baos.toByteArray();
}
/**
* Extracts raw contents from an {@code ARCRecord} (including HTTP headers).
*
* @param record the {@code ARCRecord}
* @return raw contents
* @throws IOException
*/
public static byte[] getContent(ARCRecord record) throws IOException {
ARCRecordMetaData meta = record.getMetaData();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(baos);
copyStream(record, (int) meta.getLength(), true, dout);
return baos.toByteArray();
}
/**
* Extracts contents of the body from an {@code ARCRecord} (excluding HTTP headers).
*
* @param record the {@code ARCRecord}
* @return contents of the body
* @throws IOException
*/
public static byte[] getBodyContent(ARCRecord record) throws IOException {
byte[] raw = getContent(record);
int bodyOffset = record.getBodyOffset();
byte[] content = null;
try {
content = new byte[raw.length - bodyOffset];
System.arraycopy(raw, bodyOffset, content, 0, content.length);
} catch (java.lang.NegativeArraySizeException e) {
// To find out what URL causing the error: record.getMetaData().getUrl()
// For some records, we're missing the actual content data, likely due to a crawler gitch.
// Nothing much we can do, just swallow and move on...
content = new byte[0];
}
return content;
}
private static long copyStream(final InputStream is, final int recordLength,
boolean enforceLength, final DataOutputStream out) throws IOException {
byte [] scratchbuffer = new byte[recordLength];
int read = 0;
long tot = 0;
while ((tot < recordLength) && (read = is.read(scratchbuffer)) != -1) {
int write = read;
// never write more than enforced length
write = (int) Math.min(write, recordLength - tot);
tot += read;
out.write(scratchbuffer, 0, write);
}
if (enforceLength && tot != recordLength) {
LOG.error("Read " + tot + " bytes but expected " + recordLength + " bytes. Continuing...");
}
return tot;
}
}

Event Timeline

c4science · Help