partial implementation of conference management; rewrote the whole servlets

layer to eliminate duplicate code and make error checking more efficient
(we now use a system that relies on Throwables to do interesting things)

src/com/silverwrist/venice/core/ConferenceContext.java

@@ -117,4 +117,6 @@ public interface ConferenceContext
 
   public abstract HTMLChecker getNewTopicPreviewChecker();
 
+  public abstract void fixSeen() throws DataException;
+
 } // end interface ConferenceContext

src/com/silverwrist/venice/core/impl/ConferenceUserContextImpl.java

@@ -74,6 +74,48 @@ class ConferenceUserContextImpl implements ConferenceContext, ConferenceBackend
 
   } // end class ConfCache
 
+  /*--------------------------------------------------------------------------------
+   * Internal class used in the implementation of fixSeen()
+   *--------------------------------------------------------------------------------
+   */
+
+  static class FixSeenHelper
+  {
+    private int topicid;
+    private int top_message;
+    private boolean do_insert;
+
+    public FixSeenHelper(int topicid, int top_message, boolean do_insert)
+    {
+      this.topicid = topicid;
+      this.top_message = top_message;
+      this.do_insert = do_insert;
+
+    } // end constructor
+
+    public void doFix(Statement stmt, int uid) throws SQLException
+    {
+      StringBuffer sql = new StringBuffer();
+      if (do_insert)
+      { // construct an SQL INSERT statement
+	sql.append("INSERT INTO topicsettings (topicid, uid, last_message) VALUES (").append(topicid);
+	sql.append(", ").append(uid).append(", ").append(top_message).append(");");
+
+      } // end if
+      else
+      { // construct an SQL UPDATE statement
+	sql.append("UPDATE topicsettings SET last_message = ").append(top_message).append(" WHERE topicid = ");
+	sql.append(topicid).append(" AND uid = ").append(uid).append(';');
+
+      } // end else
+
+      // now execute the update
+      stmt.executeUpdate(sql.toString());
+
+    } // end doFix
+
+  } // end class FixSeenHelper
+
   /*--------------------------------------------------------------------------------
    * Static data members
    *--------------------------------------------------------------------------------
@@ -908,6 +950,68 @@ class ConferenceUserContextImpl implements ConferenceContext, ConferenceBackend
     
   } // end getNewTopicPreviewChecker
 
+  public void fixSeen() throws DataException
+  {
+    Connection conn = null;
+
+    try
+    { // retrieve a connection from the datapool
+      conn = datapool.getConnection();
+      Statement stmt = conn.createStatement();
+
+      // lock the tables that we need
+      stmt.executeUpdate("LOCK TABLES confsettings WRITE, topicsettings WRITE, topics READ;");
+
+      try
+      { // get the existing topic list and its top messages list
+	StringBuffer sql =
+          new StringBuffer("SELECT topics.topicid, topics.top_message, ISNULL(topicsettings.last_message) "
+			   + "FROM topics LEFT JOIN topicsettings ON topics.topicid = topicsettings.topicid "
+			   + "AND topicsettings.uid = ");
+	sql.append(sig.realUID()).append(" WHERE topics.confid = ").append(confid).append(';');
+	ResultSet rs = stmt.executeQuery(sql.toString());
+
+	// use the results to build up a list of FixSeenHelpers
+	Vector tmp = new Vector();
+	while (rs.next())
+	  tmp.add(new FixSeenHelper(rs.getInt(1),rs.getInt(2),rs.getBoolean(3)));
+
+	// now iterate over the list and call doFix on each one
+	Iterator it = tmp.iterator();
+	while (it.hasNext())
+	{ // just hit each one in turn
+	  FixSeenHelper fsh = (FixSeenHelper)(it.next());
+	  fsh.doFix(stmt,sig.realUID());
+
+	} // end while
+
+	// update our last-read indicator, too
+	touchRead(conn);
+
+      } // end try
+      finally
+      { // make sure we unlock everything before we go
+	Statement ulk_stmt = conn.createStatement();
+	ulk_stmt.executeUpdate("UNLOCK TABLES;");
+
+      } // end finally
+
+    } // end try
+    catch (SQLException e)
+    { // this becomes a DataException
+      logger.error("DB error updating user information: " + e.getMessage(),e);
+      throw new DataException("unable to update user information: " + e.getMessage(),e);
+
+    } // end catch
+    finally
+    { // make sure we release the connection before we go
+      if (conn!=null)
+	datapool.releaseConnection(conn);
+
+    } // end finally
+
+  } // end fixSeen
+
   /*--------------------------------------------------------------------------------
    * Implementations from interface UserBackend
    *--------------------------------------------------------------------------------