package ua_parser;
import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import org.apache.commons.collections.map.LRUMap;
import ua_parser.Client;
import ua_parser.Device;
import ua_parser.OS;
import ua_parser.Parser;
import ua_parser.UserAgent;
/**
* When doing webanalytics (with for example PIG) the main pattern is to process
* weblogs in clickstreams. A basic fact about common clickstreams is that in
* general the same browser will do multiple requests in sequence. This has the
* effect that the same useragent will appear in the logfiles and we will see
* the need to parse the same useragent over and over again.
*
* This class introduces a very simple LRU cache to reduce the number of times
* the parsing is actually done.
*
* @author Niels Basjes
*
*/
public class CachingParser extends Parser {
// TODO: Make configurable
private static final int CACHE_SIZE = 1000;
private Map<String, Client> cacheClient = null;
private Map<String, UserAgent> cacheUserAgent = null;
private Map<String, Device> cacheDevice = null;
private Map<String, OS> cacheOS = null;
// ------------------------------------------
public CachingParser() throws IOException {
super();
}
public CachingParser(InputStream regexYaml) {
super(regexYaml);
}
// ------------------------------------------
@SuppressWarnings("unchecked")
@Override
public Client parse(String agentString) {
if (agentString == null) {
return null;
}
if (cacheClient == null) {
cacheClient = new LRUMap(CACHE_SIZE);
}
Client client = cacheClient.get(agentString);
if (client != null) {
return client;
}
client = super.parse(agentString);
cacheClient.put(agentString, client);
return client;
}
// ------------------------------------------
@SuppressWarnings("unchecked")
@Override
public UserAgent parseUserAgent(String agentString) {
if (agentString == null) {
return null;
}
if (cacheUserAgent == null) {
cacheUserAgent = new LRUMap(CACHE_SIZE);
}
UserAgent userAgent = cacheUserAgent.get(agentString);
if (userAgent != null) {
return userAgent;
}
userAgent = super.parseUserAgent(agentString);
cacheUserAgent.put(agentString, userAgent);
return userAgent;
}
// ------------------------------------------
@SuppressWarnings("unchecked")
@Override
public Device parseDevice(String agentString) {
if (agentString == null) {
return null;
}
if (cacheDevice == null) {
cacheDevice = new LRUMap(CACHE_SIZE);
}
Device device = cacheDevice.get(agentString);
if (device != null) {
return device;
}
device = super.parseDevice(agentString);
cacheDevice.put(agentString, device);
return device;
}
// ------------------------------------------
@SuppressWarnings("unchecked")
@Override
public OS parseOS(String agentString) {
if (agentString == null) {
return null;
}
if (cacheOS == null) {
cacheOS = new LRUMap(CACHE_SIZE);
}
OS os = cacheOS.get(agentString);
if (os != null) {
return os;
}
os = super.parseOS(agentString);
cacheOS.put(agentString, os);
return os;
}
// ------------------------------------------
}