[python-sybase] Connection unusable after an exception has been raised

[Dave Cole]

Skip Montanaro wrote:
> Perhaps I spoke a bit too soon...
> 
>     Dave> There are two possible ways to attempt a fix.
> 
>     Dave> 1) Construct the Fetcher in the FETCHING state.  This will mean
>     Dave>    that any exception raised in the ct_command() or the ct_send()
>     Dave>    function will result in ct_cancel(CS_CANCEL_ALL) when the
>     Dave>    Fetcher is deleted.
> 
>     Dave>      In _FetchLazy.__init__() change:
>     Dave>          self._state = _LAZY_IDLE
>     Dave>      to
>     Dave>          self._state = _LAZY_FETCHING
> 
>     Skip> This didn't work.
> 
>     Dave> 2) Set the Fetcher state to FETCHING immediately before calling
>     Dave>    ct_send() in _FetchLazy.start().
> 
>     Dave>      In _FetchLazy.start() change:
>     Dave>          status = self._cmd.ct_send()
>     Dave>      to
>     Dave>          self._set_state(_LAZY_FETCHING)
>     Dave>          status = self._cmd.ct_send()
> 
>     Skip> This did...
> 
> Solution #2 worked on Solaris/Intel, but not on Linux (neither did solution
> #1).  Cursors created after an error still give a ct_send() error with this
> message when their execute() method is called:
> 
>     ct_send(): user api layer: external error: This routine cannot be called
>     because another command structure has results pending.

Hmmm...  Looks like I have to do some more research into the CT library 
state machine.

- Dave

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