On May 12, Brian Aker wrote:
> On May 12, 2009, at 11:14 AM, Sergei Golubchik wrote:
>> - init() function. Brian added that to pass handlerton down.
>> it is ignored by any clean plugin API and should've been done
>> differently for storage engines and I_S tables.
> You should take a look at what Drizzle does as an example:
> static int compressionudf_plugin_init(PluginRegistry ®istry)
> return 0;
Yes, I've seen that :)
> If I remember correctly the void * was used because before the solution you
> had devised required that every time we updated a structure we had to
> update every single plugin (and the original pointer change was done by
> Tomas Ulin, not myself).
Right, I remember. It was inconvenient, indeed.
The main reason, of course, was that we don't have a clean external
storage engine API (compare with fulltext parser plugins - no API
changes in three years).
Still, this could've been fixed differently, without a void* pointer.
>> - MYSQL_THD is defined as void*, which is fine as it's an opaque
>> pointer, plugins are never expected to look inside to cast it to
> write_row() in the handler is another example of exposing vs encapsulation
> (which is fine... if you want to go with C over C++).
write_row() as you know, and as was mentioned in this thread, doesn't
use its argument at all. We could just as well declare it as a method
without arguments. At least it would've been less misleading.
>>> Without doing this, and using encapsulation so that a THD can have
>>> multiple Statements, it will be very difficult to work on any future
>>> parallelization efforts.
>> You mean, a Statement can have multiple THDs, I suppose :)
> No he means what he is saying. I don't know why you would want a statement
> shared across multiple THD, but having a THD be able to handle multiple
> statements means that you can do asynchronous queries within a single
Ah, okay. I see.
I thought that "parallelization", that Jay mentioned, means executing
parts of a single statement in different threads - which, indeed, may
need two THDs sharing the same Statement.
Regards / Mit vielen Grüßen,
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Sergei Golubchik <serg@stripped>
/ /|_/ / // /\ \/ /_/ / /__ Principal Software Engineer/Server Architect
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