Changeset 22973 for main/trunk/greenstone3

Timestamp:

2010-09-28T10:18:57+13:00 (14 years ago)

Author:

davidb

Message:

Code changed to use Class.forName to dynamically load required database wrapper class (e.g. GDBMWrapper or JDBMWrapper). This is so the code can be compiled up with some of these database wrapper classes optionally switched out (e.g. name changed to .java.tmp). Additional routine also added to test is a database is open. In JDBMWrapper, the close routine was modified so it only closes the database one. Our code seems to call 'cleanup' more than once, and letting it close a JDBMWrapper class a second time throws an exception deep within JDBM implementation.

Location:

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

Files:

• JDBMWrapper.java (modified) (5 diffs)
• SimpleCollectionDatabase.java (modified) (2 diffs)

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

@@ -43 +43 @@
     static String TNAME = "greenstone";
 
-    RecordManager  recman_;
+    RecordManager  recman_ = null;
     HTree          hashtable_;
+
+    String db_filename_;
 
     static private PrintWriter utf8out = null;
@@ -74 +76 @@
       // => assume the database must exist
       boolean must_exist = true; // default
-      
+
+      if (recman_ != null) {
+      String message = "openDatabase() called when the class already has a database open\n";
+      message += "  Use closeDatabase before opening the next one.\n";
+      message += "  Existing database file: " + db_filename_ + "\n";
+      message += "  New database file:      " + db_filename + "\n";
+      logger.warn(message);
+      // consider closing it automatically?
+      }
+
+
       try {
       // create or open a record manager
@@ -91 +103 @@
           if (must_exist) {
           recman_.close();
+          recman_ = null;
+          db_filename_ = null;
+
           System.err.println("Database table '" + TNAME +"' does not exist.");
           throw new IOException();
@@ -106 +121 @@
       }
 
+      db_filename_ = db_filename;
 
       return true;
@@ -114 +130 @@
   public void closeDatabase() {
       try {
-      recman_.close();
+      if (recman_ != null) {
+          recman_.close();
+          recman_ = null;
+          db_filename_ = null;
+      }
       }
       catch (IOException e) {     

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

@@ -33 +33 @@
   
   public SimpleCollectionDatabase(String db_type) {
-    if (db_type.equalsIgnoreCase("gdbm")) {
-      this.coll_db = new GDBMWrapper();
-    }
-    else if (db_type.equalsIgnoreCase("jdbm")) {
-      this.coll_db = new JDBMWrapper();
-    }
-    else {
-      logger.error("Couldn't create SimpleCollectionDatabase of type "+db_type);
-    }   
-  }
-  
+
+      // Access databaseWrapper through reflection (forName) so code
+      // can be more dynamic as to the database backends that are
+      // supported for this installation of Greenstone
+
+      String dbwrap_name = db_type.toUpperCase() + "Wrapper";
+      Class dbwrap_class = null;
+
+      try {
+      String full_dbwrap_name = "org.greenstone.gsdl3.util."+dbwrap_name;
+      dbwrap_class = Class.forName(full_dbwrap_name);
+      } 
+      catch(ClassNotFoundException e) {
+      try {
+          //try the dbwrap_name alone in case the package name is
+          //already specified
+          dbwrap_class = Class.forName(dbwrap_name);
+      } 
+      catch(ClassNotFoundException ae) {
+          logger.error("Couldn't create SimpleCollectionDatabase of type "+db_type);
+          logger.info(ae.getMessage());
+      }
+      }
+
+      try {
+      this.coll_db = (FlatDatabaseWrapper)dbwrap_class.newInstance();
+      }
+      catch(Exception e) {
+          logger.error("Failed to call the constructor "+dbwrap_name+"()");
+      }
+
+
+  }
+  
+  public boolean databaseOK() {
+      // Previously failed to open database
+      // Most likely cause is that this installation of Greenstone3 has not 
+      // been compiled with support for this database type
+      return coll_db != null;
+  }
+
   /** open the database filename, with mode mode - uses the FlatDatabaseWrapper modes */
   public boolean openDatabase(String filename, int mode){
@@ -59 +89 @@
       //   logger.warn("All the entries of the db are:");
       //   this.coll_db.displayAllEntries();
+
+      
+    if (this.coll_db==null) {
+    // Most likely cause is that this installation of Greenstone3 has not 
+    // been compiled with support for this database type
+    return null;
+    }
 
     String key_info = this.coll_db.getValue(main_key);