/**
* Copyright 2013 Twitter, Inc.
* 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 com.twitter.hbc.core.processor;
import com.twitter.hbc.common.DelimitedStreamReader;
import com.twitter.hbc.core.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nullable;
import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.BlockingQueue;
public class StringDelimitedProcessor extends AbstractProcessor<String> {
private final static Logger logger = LoggerFactory.getLogger(StringDelimitedProcessor.class);
private final static int DEFAULT_BUFFER_SIZE = 50000;
private final static int MAX_ALLOWABLE_BUFFER_SIZE = 500000;
private final static String EMPTY_LINE = "";
private DelimitedStreamReader reader;
public StringDelimitedProcessor(BlockingQueue<String> queue) {
super(queue);
}
public StringDelimitedProcessor(BlockingQueue<String> queue, long offerTimeoutMillis) {
super(queue, offerTimeoutMillis);
}
@Override
public void setup(InputStream input) {
reader = new DelimitedStreamReader(input, Constants.DEFAULT_CHARSET, DEFAULT_BUFFER_SIZE);
}
@Override @Nullable
protected String processNextMessage() throws IOException {
int delimitedCount = -1;
int retries = 0;
while (delimitedCount < 0 && retries < 3) {
String line = reader.readLine();
if (line == null) {
throw new IOException("Unable to read new line from stream");
} else if (line.equals(EMPTY_LINE)) {
return null;
}
try {
delimitedCount = Integer.parseInt(line);
} catch (NumberFormatException n) {
// resilience against the occasional malformed message
logger.warn("Error parsing delimited length", n);
}
retries += 1;
}
if (delimitedCount < 0) {
throw new RuntimeException("Unable to process delimited length");
}
if (delimitedCount > MAX_ALLOWABLE_BUFFER_SIZE) {
// this is to protect us from nastiness
throw new IOException("Unreasonable message size " + delimitedCount);
}
return reader.read(delimitedCount);
}
}