zookeeper-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Abraham Fine (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2320) C-client crashes when removing watcher asynchronously in "local" mode
Date Thu, 23 Jun 2016 20:39:16 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15347134#comment-15347134

Abraham Fine commented on ZOOKEEPER-2320:

It makes me uncomfortable to rely on the return code in unit testing, as a unit test should
do the work of making sure that the side-effects of a method match expectations.

I think return could should be fine has a mechanism for users to verify behavior, so I do
not think that the mechanism of checking the contents of the watcher hash table needs to be
exposed to users.

> C-client crashes when removing watcher asynchronously in "local" mode
> ---------------------------------------------------------------------
>                 Key: ZOOKEEPER-2320
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2320
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: c client
>    Affects Versions: 3.5.1
>            Reporter: Hadriel Kaplan
>            Assignee: Abraham Fine
>         Attachments: ZOOKEEPER-2320.patch
> The C-client library will crash when invoking the asynchronous {{zoo_aremove_watchers()}}
API function with the '{{local}}' argument set to 1.
> The reason is: if the local argument is 1/true, then the code does '{{notify_sync_completion((struct
sync_completion *)data);}}' But casting the '{{data}}' variable to a {{sync_completion}} struct
pointer is bogus/invalid, and when it's later handles as that struct pointer it's accessing
invalid memory.
> As a side note: it will work ok when called _synchronously_ through {{zoo_remove_watchers()}},
because that function creates a {{sync_completion}} struct and passes it to the asynch {{zoo_aremove_watchers()}},
but it will not work ok when the asynch function is used directly for the reason stated perviously.
> Another side note: the docs state that setting the 'local' flag makes the C-client remove
the watcher "even if there is no server connection" - but really it makes the C-client remove
the watcher without notifying the server at *all*, even if the connection to a server is up.
(well... that's what it would do if it didn't just crash instead ;)

This message was sent by Atlassian JIRA

View raw message