Changeset 21431 for main/trunk/greenstone3/src/java/org/greenstone/gsdl3/util/JDBMWrapper.java

Timestamp:

2010-01-06T16:52:28+13:00 (14 years ago)

Author:

davidb

Message:

Initial implementation for JDBM Database backend. Tested on the gs2mgppdemo collection

File:

• main/trunk/greenstone3/src/java/org/greenstone/gsdl3/util/JDBMWrapper.java (modified) (4 diffs)

main/trunk/greenstone3/src/java/org/greenstone/gsdl3/util/JDBMWrapper.java

@@ -21 +21 @@
 import org.apache.log4j.Logger;
 
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+
+import java.util.Properties;
+import java.util.ArrayList;
+
+import jdbm.RecordManager;
+import jdbm.RecordManagerFactory;
+import jdbm.helper.FastIterator;
+import jdbm.htree.HTree;
+
 public class JDBMWrapper
   implements FlatDatabaseWrapper {
@@ -26 +41 @@
   static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.JDBMWrapper.class.getName());
 
+    static String TNAME = "greenstone";
+
+    RecordManager  recman_;
+    HTree          hashtable_;
+
+    static private PrintWriter utf8out = null;
+
+    static
+    {
+        try {
+            OutputStreamWriter osw = new OutputStreamWriter(System.out, "UTF-8");
+            utf8out = new PrintWriter(osw, true);
+        }
+        catch (UnsupportedEncodingException e) {
+            System.out.println(e);
+        }
+    }
+
+
   /** open database named filename, using mode */
-  public boolean openDatabase(String filename, int mode) {
-    return false;
+  public boolean openDatabase(String db_filename, int mode) {
+      
+
+      if (db_filename.endsWith(".jdb")) {
+      // remove file extension as JDBM does not expect it
+      db_filename = db_filename.substring(0,db_filename.length()-4);
+      }
+
+      // Map the mode value into equivalent JDBM 'must_exist' value
+      // currently this is very simple as there is only READ and WRITE
+      // (no WRITER_CREATE)
+      // => assume the database must exist
+      boolean must_exist = true; // default
+      
+      try {
+      // create or open a record manager
+      Properties props = new Properties();
+      recman_ = RecordManagerFactory.createRecordManager(db_filename, props);
+      
+      // load existing table (if exists) otherwise create new one
+      long recid = recman_.getNamedObject(TNAME);
+      
+      if (recid != 0) {
+          System.err.println("# Loading existing database table '" + TNAME +"' ...");
+          hashtable_ = HTree.load(recman_, recid);
+      }
+      else {
+          
+          if (must_exist) {
+          recman_.close();
+          System.err.println("Database table '" + TNAME +"' does not exist.");
+          throw new IOException();
+          }
+          else {
+          System.err.println("# No database table '" + TNAME +"' to set.  Creating new one");
+            hashtable_ = HTree.createInstance(recman_);
+            recman_.setNamedObject(TNAME, hashtable_.getRecid());
+        }
+      }
+      }
+      catch (IOException e) {     
+    logger.error("couldn't open database "+ db_filename);
+    return false;
+      }
+
+
+      return true;
   }
 
@@ -34 +113 @@
   /** close the database associated with this wrapper */
   public void closeDatabase() {
-
+      try {
+      recman_.close();
+      }
+      catch (IOException e) {     
+    logger.error("Failed to close JDBM database");
+      }
   }
 
   /** returns the value associated with the key */
   public String getValue(String key) {
-    return null;
+
+      String val;
+
+      try {
+      val = (String) hashtable_.get(key);
+        
+      recman_.commit();
+      }
+      catch (IOException e) {     
+    logger.error("Failed get key " + key + "from JDBM database");
+    return null;
+      }
+
+      return val;
   }
 
@@ -45 +142 @@
    *    printed for debugging purposes*/
   public String displayAllEntries() {
-    return "No entries.";
+
+      StringBuffer keys = new StringBuffer();
+
+      try {
+      FastIterator   iter = hashtable_.keys();
+      String         key  = (String) iter.next();
+      
+      String nl = System.getProperty("line.separator");
+      
+      while (key != null) {
+          String val = (String) hashtable_.get(key);
+          keys.append("[" + key + "]" + nl);
+          keys.append(val + nl);
+          // 70 hypens
+          keys.append("----------------------------------------------------------------------" + nl);
+          key = (String) iter.next();
+      }
+
+      recman_.commit();
+      }
+      catch (IOException e) {     
+    logger.error("Failed get all keys and values from JDBM database");
+    return null;
+      }
+        
+      return keys.toString();
   }
 }