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[DL-Learner SVN] SF.net SVN: dl-learner: [383] trunk/src/dl-learner/org/dllearner/kb/sparql/ Cache.java
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From: <ku...@us...> - 2008-01-18 07:49:33
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Revision: 383
http://dl-learner.svn.sourceforge.net/dl-learner/?rev=383&view=rev
Author: kurzum
Date: 2008-01-17 23:49:29 -0800 (Thu, 17 Jan 2008)
Log Message:
-----------
commented cache
Modified Paths:
--------------
trunk/src/dl-learner/org/dllearner/kb/sparql/Cache.java
Modified: trunk/src/dl-learner/org/dllearner/kb/sparql/Cache.java
===================================================================
--- trunk/src/dl-learner/org/dllearner/kb/sparql/Cache.java 2008-01-16 15:42:53 UTC (rev 382)
+++ trunk/src/dl-learner/org/dllearner/kb/sparql/Cache.java 2008-01-18 07:49:29 UTC (rev 383)
@@ -29,36 +29,61 @@
import java.util.HashMap;
/**
- * SPARQL query cache to avoid possibly expensive multiple queries.
+ * SPARQL query cache to avoid possibly expensive multiple queries. An object of
+ * this class can be the cache itself or a cache object(one entry), We could
+ * split that in two classes, but one entry o object only has contains data and
+ * one additional function and would just be a data class
*
+ * it writes the files according to one resource in the basedir and saves the
+ * cache object in it.
+ *
* @author Sebastian Hellmann
- *
+ *
*/
public class Cache implements Serializable {
- // Object can be the cache itself
- // or a cache object(one entry)
- // it now uses a hashmap and can contain different queries at once
- private HashMap<String, String> hm;
+ /**
+ * This maps sparql query to sparql result
+ */
+ protected HashMap<String, String> hm;
+
final static long serialVersionUID = 104;
transient String basedir = "";
transient String fileending = ".cache";
+ transient boolean debug_print_flag = false;
long timestamp;
- long daysoffreshness = 15;
- long multiplier = 24 * 60 * 60 * 1000;// h m s ms
+ /**
+ * After how many days cache entries get invalid
+ */
+ protected long daysoffreshness = 15;
+ protected long multiplier = 24 * 60 * 60 * 1000;// h m s ms
+
// private HashMap<String, String> inmem_cache;
- // constructor for the cache itself
+ //
+ /**
+ * constructor for the cache itself
+ *
+ * @param path
+ * where the cache files will be
+ */
public Cache(String path) {
this.basedir = path + File.separator;
if (!new File(path).exists()) {
- System.out.println(new File(path).mkdir());
- ;
+ System.out.println("created directory: " + path + " : "
+ + new File(path).mkdir());
+
}
}
// constructor for single cache object(one entry)
- public Cache(String sparql, String content) {
+ /**
+ * @param sparql
+ * query
+ * @param content
+ * that is the sparql query result as xml
+ */
+ protected Cache(String sparql, String content) {
// this.content = c;
// this.sparqlquery = sparql;
this.timestamp = System.currentTimeMillis();
@@ -66,7 +91,17 @@
hm.put(sparql, content);
}
- public String get(String key, String sparql) {
+ /**
+ * gets a chached sparqlquery for a resource(key) and returns the
+ * sparqlXMLResult or null, if none is found.
+ *
+ * @param key
+ * is the resource, the identifier
+ * @param sparqlquery
+ * is a special sparql query about that resource
+ * @return sparqlXMLResult
+ */
+ public String get(String key, String sparqlquery) {
// System.out.println("get From "+key);
String ret = null;
try {
@@ -79,7 +114,7 @@
// System.out.println("fresh");
String xml = "";
try {
- xml = c.hm.get(sparql);
+ xml = c.hm.get(sparqlquery);
} catch (Exception e) {
return null;
}
@@ -90,22 +125,37 @@
e.printStackTrace();
}
return ret;
- };
+ }
- public void put(String key, String sparql, String content) {
+ /**
+ * @param key
+ * is the resource, the identifier
+ * @param sparqlquery
+ * is the query used as another identifier
+ * @param content
+ * is the result of the query
+ */
+ public void put(String key, String sparqlquery, String content) {
// System.out.println("put into "+key);
Cache c = readFromFile(makeFilename(key));
if (c == null) {
- c = new Cache(sparql, content);
+ c = new Cache(sparqlquery, content);
putIntoFile(makeFilename(key), c);
} else {
- c.hm.put(sparql, content);
+ c.hm.put(sparqlquery, content);
putIntoFile(makeFilename(key), c);
}
}
- String makeFilename(String key) {
+ /**
+ * this function takes a resource string and then URIencodes it and makes a
+ * filename out of it for the use in the hashmap
+ *
+ * @param key
+ * @return the complete key for filename in the hashmap
+ */
+ protected String makeFilename(String key) {
String ret = "";
try {
ret = basedir + URLEncoder.encode(key, "UTF-8") + fileending;
@@ -115,14 +165,6 @@
return ret;
}
- boolean checkFreshness() {
- if ((System.currentTimeMillis() - this.timestamp) <= (daysoffreshness * multiplier))
- // fresh
- return true;
- else
- return false;
- }
-
public void checkFile(String Filename) {
if (!new File(Filename).exists()) {
try {
@@ -135,12 +177,18 @@
}
- public void putIntoFile(String Filename, Cache content) {
+ /**
+ * puts a cache entry in a file
+ *
+ * @param Filename
+ * @param c
+ */
+ protected void putIntoFile(String Filename, Cache c) {
try {
// FileWriter fw=new FileWriter(new File(Filename),true);
FileOutputStream fos = new FileOutputStream(Filename, false);
ObjectOutputStream o = new ObjectOutputStream(fos);
- o.writeObject(content);
+ o.writeObject(c);
fos.flush();
fos.close();
} catch (Exception e) {
@@ -148,7 +196,13 @@
}
}
- public Cache readFromFile(String Filename) {
+ /**
+ * reads a cache entry from a file
+ *
+ * @param Filename
+ * @return cache entry
+ */
+ protected Cache readFromFile(String Filename) {
Cache content = null;
try {
FileInputStream fos = new FileInputStream(Filename);
@@ -161,5 +215,13 @@
return content;
}
-
+
+ protected boolean checkFreshness() {
+ if ((System.currentTimeMillis() - this.timestamp) <= (daysoffreshness * multiplier))
+ // fresh
+ return true;
+ else
+ return false;
+ }
+
}
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