Class TransactionResourceImpl

java.lang.Object
org.apache.derby.impl.jdbc.TransactionResourceImpl
public final class TransactionResourceImpl extends Object
An instance of a TransactionResourceImpl is a bundle of things that connects a connection to the database - it is the transaction "context" in a generic sense. It is also the object of synchronization used by the connection object to make sure only one thread is accessing the underlying transaction and context.

TransactionResourceImpl not only serves as a transaction "context", it also takes care of:

  1. context management: the pushing and popping of the context manager in and out of the global context service
  2. transaction demarcation: all calls to commit/abort/prepare/close a transaction must route thru the transaction resource.
  3. error handling

The only connection that have access to the TransactionResource is the root connection, all other nested connections (called proxyConnection) accesses the TransactionResource via the root connection. The root connection may be a plain EmbedConnection, or a DetachableConnection (in case of a XATransaction). A nested connection must be a ProxyConnection. A proxyConnection is not detachable and can itself be a XA connection - although an XATransaction may start nested local (proxy) connections.

this is an example of how all the objects in this package relate to each other. In this example, the connection is nested 3 deep. DetachableConnection. 


      lcc  cm   database  jdbcDriver
       ^    ^    ^         ^ 
       |    |    |         |
      |======================|
      | TransactionResource  |
      |======================|
             ^  |
             |  |
             |  |      |---------------rootConnection----------|
             |  |      |                                       |
             |  |      |- rootConnection-|                     |
             |  |      |                 |                     |
             |  V      V                 |                     |
|========================|      |=================|      |=================|
|    EmbedConnection     |      | EmbedConnection |      | EmbedConnection |
|                        |<-----|                 |<-----|                 |
| (DetachableConnection) |      | ProxyConnection |      | ProxyConnection |
|========================|      |=================|      |=================|
   ^                 | ^             ^                        ^
   |                 | |             |                        |
   ---rootConnection-- |             |                        |
                       |             |                        |
                       |             |                        |
 |======================|  |======================|  |======================|
 | ConnectionChild |  | ConnectionChild |  | ConnectionChild |
 |                      |  |                      |  |                      |
 |  (EmbedStatement)    |  |  (EmbedResultSet)    |  |  (...)               |
 |======================|  |======================|  |======================|

A plain local connection must be attached (doubly linked with) to a TransactionResource at all times. A detachable connection can be without a TransactionResource, and a TransactionResource for an XATransaction (called XATransactionResource) can be without a connection.

  • Field Details

  • Constructor Details

  • Method Details

    • setDatabase

      void setDatabase(Database db)
      Called only in EmbedConnection construtor. The Local Connection sets up the database in its constructor and sets it here.

    • startTransaction

      void startTransaction() throws StandardException, SQLException
      Throws:
      StandardException
      SQLException

    • getDriver

      InternalDriver getDriver()
      Return instance variables to EmbedConnection. RESOLVE: given time, we should perhaps stop giving out reference to these things but instead use the transaction resource itself.

    • getCsf

      ContextService getCsf()

    • getContextManager

      ContextManager getContextManager()
      need to be public because it is in the XATransactionResource interface

    • getLcc

      LanguageConnectionContext getLcc()

    • getDBName

      String getDBName()

    • getUrl

      String getUrl()

    • getDatabase

      Database getDatabase()

    • shutdownDatabaseException

      StandardException shutdownDatabaseException()

    • commit

      void commit() throws StandardException
      local transaction demarcation - note that global or xa transaction cannot commit thru the connection, they can only commit thru the XAResource, which uses the xa_commit or xa_rollback interface as a safeguard.
      Throws:
      StandardException

    • rollback

      void rollback() throws StandardException
      Throws:
      StandardException

    • clearContextInError

      void clearContextInError()
      An error happens in the constructor, pop the context.

    • clearLcc

      void clearLcc()
      Resolve: probably superfluous

    • setupContextStack

      final void setupContextStack()

    • restoreContextStack

      final void restoreContextStack()

    • handleException

      final SQLException handleException(Throwable thrownException, boolean autoCommit, boolean rollbackOnAutoCommit) throws SQLException
      clean up the error and wrap the real exception in some SQLException.
      Throws:
      SQLException

    • isLoginException

      private boolean isLoginException(Throwable thrownException)
      Determine if the exception thrown is a login exception. Needed for DERBY-5427 fix to prevent inappropriate thread dumps and javacores. This exception is special because it is SESSION_SEVERITY and database.isActive() is true, but the session hasn't started yet,so it is not an actual crash and should not report extended diagnostics.
      Parameters:
      thrownException -
      Returns:
      true if this is a login failure exception

    • wrapInSQLException

      public static SQLException wrapInSQLException(Throwable thrownException)
      Wrap a Throwable in an SQLException.
      Parameters:
      thrownException - a Throwable
      Returns:
      thrownException, if it is an SQLException; otherwise, an SQLException which wraps thrownException

    • getUserName

      String getUserName()

    • cleanupOnError

      boolean cleanupOnError(Throwable e, boolean diagActive)
      clean up error and print it to derby.log if diagActive is true
      Parameters:
      e - the error we want to clean up
      diagActive - true if extended diagnostics should be considered, false not interested of extended diagnostic information
      Returns:
      true if the context manager is shutdown, false otherwise.

    • isIdle

      boolean isIdle()

    • isActive

      boolean isActive()