On 06/16/2016 07:35 PM, Dimitry Sibiryakov wrote:
> Hello, All.
>
> Currently GPRE used to generate code like this:
>
>> static Firebird::IRequest*
>> fb_396 = 0; /* request handle */
>>
>> for (int retries = 0; retries < 2; ++retries)
>> {
>> {
>> if (!DB)
>> DB = fbProvider->attachDatabase(fbStatus,
>> isqlGlob.global_Db_name, 0, NULL);
>> if (DB && !fbTrans)
>> fbTrans = DB->startTransaction(fbStatus, 0, NULL);
>> }
>> if (!fb_396 && fbTrans && DB)
>> fb_396 = DB->compileRequest(fbStatus, sizeof(fb_397), fb_397);
>> if (fbTrans && fb_396)
>> fb_396->start(fbStatus, fbTrans, 0);
>> if (fbStatus->getErrors()[1] == isc_bad_req_handle) {
>> fb_396->release(); fb_396 = NULL; }
>> else break;
>> }
>> if (!(fbStatus->getState() & Firebird::IStatus::STATE_ERRORS)) {
> But if between two calls of this code database was disconnected, memory,
> allocated for
> fb_396 can be already freed
It can't - this is reference counted object. This is what you miss.
> , so call of fb_396->start() result in crash.
> Consider, for example, following script:
>
>> connect a;
>> show generators;
>> commit;
>> connect b;
>> show generators;
> Why it doesn't crash? Pure luck or there is protection that I don't see?
>
This is reference counted object, and it will not be actually deleted as
long as
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