Re: Interrupting long external library calls

On 16.05.2012 14:30, Mark Cave-Ayland wrote:
> On 16/05/12 11:39, Heikki Linnakangas wrote:
>
>> However, if you're absolutely positively sure that the library function
>> can tolerate that, you can set "ImmediateInterruptOK = true" before
>> calling it. See e.g PGSemaphoreLock() on how that's done before starting
>> to sleep on a semapgore.
>
> Hi Heikki,
>
> Yes that appears to work fine on the surface - just testing now to
> determine what state everything is left in when queries are aborted
> prematurely.

You're unlikely to catch all problems just by testing. I wouldn't trust 
that it's safe unless the library authors specifically mentions that it 
is safe to longjump out of the function at any time. Note for example 
that if the library function calls back to palloc/pfree, then it's not 
safe, because interrupting those functions is not safe.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com