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/*******************************************************************************
* ============LICENSE_START==================================================
* * org.onap.dmaap
* * ===========================================================================
* * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
* * ===========================================================================
* * 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.
* * ============LICENSE_END====================================================
* *
* * ECOMP is a trademark and service mark of AT&T Intellectual Property.
* *
******************************************************************************/
package com.att.research.datarouter.node;
import java.util.*;
import java.io.*;
/**
* Track redirections of subscriptions
*/
public class RedirManager {
private Hashtable<String, String> sid2primary = new Hashtable<String, String>();
private Hashtable<String, String> sid2secondary = new Hashtable<String, String>();
private String redirfile;
RateLimitedOperation op;
/**
* Create a mechanism for maintaining subscription redirections.
* @param redirfile The file to store the redirection information.
* @param mininterval The minimum number of milliseconds between writes to the redirection information file.
* @param timer The timer thread used to run delayed file writes.
*/
public RedirManager(String redirfile, long mininterval, Timer timer) {
this.redirfile = redirfile;
op = new RateLimitedOperation(mininterval, timer) {
public void run() {
try {
StringBuffer sb = new StringBuffer();
for (String s: sid2primary.keySet()) {
sb.append(s).append(' ').append(sid2primary.get(s)).append(' ').append(sid2secondary.get(s)).append('\n');
}
OutputStream os = new FileOutputStream(RedirManager.this.redirfile);
os.write(sb.toString().getBytes());
os.close();
} catch (Exception e) {
}
}
};
try {
String s;
BufferedReader br = new BufferedReader(new FileReader(redirfile));
while ((s = br.readLine()) != null) {
s = s.trim();
String[] sx = s.split(" ");
if (s.startsWith("#") || sx.length != 3) {
continue;
}
sid2primary.put(sx[0], sx[1]);
sid2secondary.put(sx[0], sx[2]);
}
br.close();
} catch (Exception e) {
// missing file is normal
}
}
/**
* Set up redirection. If a request is to be sent to subscription ID sid, and that is configured to go to URL primary, instead, go to secondary.
* @param sid The subscription ID to be redirected
* @param primary The URL associated with that subscription ID
* @param secondary The replacement URL to use instead
*/
public synchronized void redirect(String sid, String primary, String secondary) {
sid2primary.put(sid, primary);
sid2secondary.put(sid, secondary);
op.request();
}
/**
* Cancel redirection. If a request is to be sent to subscription ID sid, send it to its primary URL.
* @param sid The subscription ID to remove from the table.
*/
public synchronized void forget(String sid) {
sid2primary.remove(sid);
sid2secondary.remove(sid);
op.request();
}
/**
* Look up where to send a subscription. If the primary has changed or there is no redirection, use the primary. Otherwise, redirect to the secondary URL.
* @param sid The subscription ID to look up.
* @param primary The configured primary URL.
* @return The destination URL to really use.
*/
public synchronized String lookup(String sid, String primary) {
String oprim = sid2primary.get(sid);
if (primary.equals(oprim)) {
return(sid2secondary.get(sid));
} else if (oprim != null) {
forget(sid);
}
return(primary);
}
/**
* Is a subscription redirected?
*/
public synchronized boolean isRedirected(String sid) {
return(sid != null && sid2secondary.get(sid) != null);
}
}
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