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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (DERBY-3457) Closing a logical connection must close all associated logical statements
Date Wed, 27 Feb 2008 13:41:51 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12572906#action_12572906
] 

kristwaa edited comment on DERBY-3457 at 2/27/08 5:41 AM:
-----------------------------------------------------------------

'derby-3457-1c-stmt_closing.diff' adds the closing logic for logical statements.
The basic approach taken is that each new logical statement is registered by the StatementCacheInteractor.
When a logical statement is explicitly closed, it removes itself from the list of open statements.
When the caching logical connection is closed, it iterates through the list of open statements
and closes them.

Possible issues:
 a) What should happen if closing a statement throws exception?
    Currently, the close procedure is aborted, and I'm not quite sure what state the connection
is left in.
    The close can fail on statement reset, or on physical statement close. Not sure which
errors can occur, except for network problems.

There is also a possible issue with calling super.close in CachingLogicalConnection. That
method cannot close open statements when called from a CLC, but it should do it when called
on a LogicalConnection. This suggests a bug somewhere, and I have to look into this to determine
if the existing LogicalConnection has a bug, or if it is the new code I have added.

Patch 1c ready for review.

      was (Author: kristwaa):
    'derby-3457-1c-stmt_closing.diff' adds the closing logic for logical statements.
The basic approach taken is that each new logical statement is registered by the StatementCacheInteractor.
When a logical statement is explicitly closed, it removes itself from the list of open statements.
When the caching logical connection is closed, it iterates through the list of open statements
and closes them.

Possible issues:
 a) What should happen if closing a statement throws exception?
    Currently, the close procedure is aborted, and I'm not quite sure what state the connection
is left in.
    The close can fail on statement reset, or on physical statement close. Not sure which
errors can occur, except for network problems.

There is also a possible issue with calling super.close in CachingLogicalConnection. That
method cannot close open statements when called from a CLC, but it should do it when called
on a LogicalConnection. This suggests a bug somewhere, and I have to look into this to determine
if the existing LogicalConnection has a bug, or if it is the new code I have added.

Patch 1d ready for review.
  
> Closing a logical connection must close all associated logical statements
> -------------------------------------------------------------------------
>
>                 Key: DERBY-3457
>                 URL: https://issues.apache.org/jira/browse/DERBY-3457
>             Project: Derby
>          Issue Type: Task
>          Components: JDBC, Network Client
>    Affects Versions: 10.4.0.0
>         Environment: Client-server with statement pooling enabled in the client driver.
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>             Fix For: 10.4.0.0
>
>         Attachments: derby-3457-1a-stmt_closing.diff, derby-3457-1a-stmt_closing.stat,
derby-3457-1b-stmt_closing.diff, derby-3457-1c-stmt_closing.diff, derby-3457-2a-stmt_registration.diff
>
>
> When a logical connection is closed, all open logical statements created by this connection
must be closed.
> The closing is important per the general principle of cleaning up resources, but especially
so in the case of statement pooling, as not closing the logical statement can cause side effects
on another logical connection (sharing the same physical connection).

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