[Mulgara-svn] r450 - branches/nw-interface/src/jar/itql/java/org/mulgara/itql

[pag at mulgara.org]

Author: pag
Date: 2007-09-24 16:01:42 -0500 (Mon, 24 Sep 2007)
New Revision: 450

Modified:
   branches/nw-interface/src/jar/itql/java/org/mulgara/itql/TqlAutoInterpreter.java
Log:
Checks for entering and leaving transactions, and sets the state on connections appropriately.

Modified: branches/nw-interface/src/jar/itql/java/org/mulgara/itql/TqlAutoInterpreter.java
===================================================================
--- branches/nw-interface/src/jar/itql/java/org/mulgara/itql/TqlAutoInterpreter.java	2007-09-24 21:00:59 UTC (rev 449)
+++ branches/nw-interface/src/jar/itql/java/org/mulgara/itql/TqlAutoInterpreter.java	2007-09-24 21:01:42 UTC (rev 450)
@@ -12,12 +12,13 @@
 package org.mulgara.itql;
 
 import java.net.URI;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.Collection;
+import java.util.LinkedList;
 
 import org.apache.log4j.Logger;
 import org.mulgara.connection.Connection;
 import org.mulgara.connection.ConnectionException;
+import org.mulgara.connection.ConnectionFactory;
 import org.mulgara.parser.Interpreter;
 import org.mulgara.query.Answer;
 import org.mulgara.query.QueryException;
@@ -49,14 +50,20 @@
   /** The most recent exception, if there was one. */
   private Exception lastException;
 
-  /** Cached connections to servers. Duplicates may exist if more than one URI is used to refer to the same server. */
-  private Map<URI,Connection> establishedConnections = new HashMap<URI,Connection>();
-  
+  /** Factory for building and caching connections. */
+  private ConnectionFactory connectionFactory = new ConnectionFactory();
 
+  /** Indicates that the client is in a transaction. */
+  private boolean inTransaction;
+
+  /** All the connections involved in the current transaction. */
+  private Collection<Connection> transConnections = new LinkedList<Connection>();
+
   /**
    * Creates a new autointerpreter with no prior connections.
    */
   public TqlAutoInterpreter() {
+    inTransaction = false;
     resetState();
   }
   
@@ -83,6 +90,7 @@
       // set up a connection, if required
       Connection conn = cmd.isLocalOperation() ? null : establishConnection(cmd.getServerURI());
       cmd.execute(conn);
+      updateOnConnectionState(conn);
       lastMessage = cmd.getResultMessage();
     } catch (Exception e) {
       lastException = e;
@@ -94,6 +102,28 @@
   }
 
 
+  /**
+   * Perform any actions required on the update of the state of a connection.
+   * @param conn The connection whose state needs checking.
+   * @throws QueryException Can be caused by a failed change into a transaction.
+   */
+  private void updateOnConnectionState(Connection conn) throws QueryException {
+    // check if the transaction state changed.
+    if (inTransaction == conn.getAutoCommit()) {
+      // update the client state
+      inTransaction = !conn.getAutoCommit();
+      if (inTransaction) {
+        // Started a transaction. All connection changes set this state on the new connection.
+        assert transConnections.isEmpty();
+      } else {
+        // Closed a transaction. Commit all outstanding transactions.
+        for (Connection c: transConnections) c.setAutoCommit(true);
+        transConnections.clear();
+      }
+    }
+  }
+
+
   /** @return the message set from the last operation */
   public String getLastMessage() { return lastMessage; }
 
@@ -108,13 +138,7 @@
    * Close any resources that are still in use.
    */
   public void close() {
-    for (Connection c: establishedConnections.values()) {
-      try {
-        c.close();
-      } catch (QueryException e) {
-        logger.warn("Unable to close connection", e);
-      }
-    }
+    connectionFactory.closeAll();
   }
 
 
@@ -133,13 +157,16 @@
    * @param serverUri The URI for the server to get a connection to.
    * @return A connection to the server, cached if available.
    * @throws ConnectionException It was not possible to create a connection to the described server.
+   * @throws QueryException There is a transaction underway, but the new connection cannot turn off autocommit.
    */
-  private Connection establishConnection(URI serverUri) throws ConnectionException {
+  private Connection establishConnection(URI serverUri) throws ConnectionException, QueryException {
     if (serverUri == null) throw new IllegalArgumentException("Server URI may not be null.");
-    Connection connection = establishedConnections.get(serverUri);
-    if (connection == null) {
-      connection = new Connection(serverUri);
-      establishedConnections.put(serverUri, connection);
+    Connection connection = connectionFactory.newConnection(serverUri);
+    // If in a transaction, turn off autocommit 
+    if (inTransaction && connection.getAutoCommit()) {
+      connection.setAutoCommit(false);
+      assert !transConnections.contains(connection);
+      transConnections.add(connection);
     }
     return connection;
   }