/*
* 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.kafka.connect.file;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import org.apache.kafka.connect.data.Schema;
import org.apache.kafka.connect.errors.ConnectException;
import org.apache.kafka.connect.source.SourceRecord;
import org.apache.kafka.connect.source.SourceTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* FileStreamSourceTask reads from stdin or a file.
*/
public class FileStreamSourceTask extends SourceTask {
private static final Logger log = LoggerFactory.getLogger(FileStreamSourceTask.class);
public static final String FILENAME_FIELD = "filename";
public static final String POSITION_FIELD = "position";
private static final Schema VALUE_SCHEMA = Schema.STRING_SCHEMA;
private String filename;
private InputStream stream;
private BufferedReader reader = null;
private char[] buffer = new char[1024];
private int offset = 0;
private String topic = null;
private Long streamOffset;
@Override
public String version() {
return new FileStreamSourceConnector().version();
}
@Override
public void start(Map<String, String> props) {
filename = props.get(FileStreamSourceConnector.FILE_CONFIG);
if (filename == null || filename.isEmpty()) {
stream = System.in;
// Tracking offset for stdin doesn't make sense
streamOffset = null;
reader = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8));
}
topic = props.get(FileStreamSourceConnector.TOPIC_CONFIG);
if (topic == null)
throw new ConnectException("FileStreamSourceTask config missing topic setting");
}
@Override
public List<SourceRecord> poll() throws InterruptedException {
if (stream == null) {
try {
stream = new FileInputStream(filename);
Map<String, Object> offset = context.offsetStorageReader().offset(Collections.singletonMap(FILENAME_FIELD, filename));
if (offset != null) {
Object lastRecordedOffset = offset.get(POSITION_FIELD);
if (lastRecordedOffset != null && !(lastRecordedOffset instanceof Long))
throw new ConnectException("Offset position is the incorrect type");
if (lastRecordedOffset != null) {
log.debug("Found previous offset, trying to skip to file offset {}", lastRecordedOffset);
long skipLeft = (Long) lastRecordedOffset;
while (skipLeft > 0) {
try {
long skipped = stream.skip(skipLeft);
skipLeft -= skipped;
} catch (IOException e) {
log.error("Error while trying to seek to previous offset in file: ", e);
throw new ConnectException(e);
}
}
log.debug("Skipped to offset {}", lastRecordedOffset);
}
streamOffset = (lastRecordedOffset != null) ? (Long) lastRecordedOffset : 0L;
} else {
streamOffset = 0L;
}
reader = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8));
log.debug("Opened {} for reading", logFilename());
} catch (FileNotFoundException e) {
log.warn("Couldn't find file {} for FileStreamSourceTask, sleeping to wait for it to be created", logFilename());
synchronized (this) {
this.wait(1000);
}
return null;
}
}
// Unfortunately we can't just use readLine() because it blocks in an uninterruptible way.
// Instead we have to manage splitting lines ourselves, using simple backoff when no new data
// is available.
try {
final BufferedReader readerCopy;
synchronized (this) {
readerCopy = reader;
}
if (readerCopy == null)
return null;
ArrayList<SourceRecord> records = null;
int nread = 0;
while (readerCopy.ready()) {
nread = readerCopy.read(buffer, offset, buffer.length - offset);
log.trace("Read {} bytes from {}", nread, logFilename());
if (nread > 0) {
offset += nread;
if (offset == buffer.length) {
char[] newbuf = new char[buffer.length * 2];
System.arraycopy(buffer, 0, newbuf, 0, buffer.length);
buffer = newbuf;
}
String line;
do {
line = extractLine();
if (line != null) {
log.trace("Read a line from {}", logFilename());
if (records == null)
records = new ArrayList<>();
records.add(new SourceRecord(offsetKey(filename), offsetValue(streamOffset), topic, null,
null, null, VALUE_SCHEMA, line, System.currentTimeMillis()));
}
} while (line != null);
}
}
if (nread <= 0)
synchronized (this) {
this.wait(1000);
}
return records;
} catch (IOException e) {
// Underlying stream was killed, probably as a result of calling stop. Allow to return
// null, and driving thread will handle any shutdown if necessary.
}
return null;
}
private String extractLine() {
int until = -1, newStart = -1;
for (int i = 0; i < offset; i++) {
if (buffer[i] == '\n') {
until = i;
newStart = i + 1;
break;
} else if (buffer[i] == '\r') {
// We need to check for \r\n, so we must skip this if we can't check the next char
if (i + 1 >= offset)
return null;
until = i;
newStart = (buffer[i + 1] == '\n') ? i + 2 : i + 1;
break;
}
}
if (until != -1) {
String result = new String(buffer, 0, until);
System.arraycopy(buffer, newStart, buffer, 0, buffer.length - newStart);
offset = offset - newStart;
if (streamOffset != null)
streamOffset += newStart;
return result;
} else {
return null;
}
}
@Override
public void stop() {
log.trace("Stopping");
synchronized (this) {
try {
if (stream != null && stream != System.in) {
stream.close();
log.trace("Closed input stream");
}
} catch (IOException e) {
log.error("Failed to close FileStreamSourceTask stream: ", e);
}
this.notify();
}
}
private Map<String, String> offsetKey(String filename) {
return Collections.singletonMap(FILENAME_FIELD, filename);
}
private Map<String, Long> offsetValue(Long pos) {
return Collections.singletonMap(POSITION_FIELD, pos);
}
private String logFilename() {
return filename == null ? "stdin" : filename;
}
}