[asterisk-dev] [Code Review]: Add SQLite 3 realtime driver

[Tilghman Lesher]

> On Sept. 5, 2011, 2:11 p.m., Tilghman Lesher wrote:
> > /trunk/res/res_config_sqlite3.c, lines 878-880
> > <https://reviewboard.asterisk.org/r/1408/diff/3/?file=19946#file19946line878>
> >
> >     The last type may not work well for type INTEGER, because integers are converted internally to signed 8-byte integers.  Any part of the unsigned value will therefore be converted to negative or worse, truncated.  Nothing currently in Asterisk uses that type, yet, so it's not a big concern, but RQ_UINTEGER8 should probably be treated as a "TEXT" anyway, for future compatibility.
> 
> Terry Wilson wrote:
>     There are no types in sqlite3 anyway, just type affinity. You can store any kind of data in any kind of field in sqlite. You can store "Tilghman was here" in an integer column. The sqlite3_exec callback will return everything back as a text field anyway.
>     
>     
>     sqlite> CREATE TABLE sipregs (name TEXT, ipaddr TEXT, port INTEGER, regseconds INTEGER, defaultuser TEXT, fullcontact TEXT, regserver TEXT, useragent TEXT, lastms INTEGER);
>     sqlite> insert into sipregs (lastms) values ("hello");
>     sqlite> select * from sipregs;
>     ||||||||hello
>

I'm talking about the internal discussion of SQLite 3, which stores integers according to their scale (1, 2, 3, 4, 6, or 8 bytes), but converts all integers to signed 8-byte integers for use internally.  I'm mainly concerned about a loss in precision, but it's purely theoretical for the time being, as we don't (yet) use the corresponding constant.  We can put this off for the time being; just know that it's a possible concern.


- Tilghman


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On Sept. 3, 2011, 11:08 p.m., Terry Wilson wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/1408/
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> 
> (Updated Sept. 3, 2011, 11:08 p.m.)
> 
> 
> Review request for Asterisk Developers, Olle E Johansson and Tilghman Lesher.
> 
> 
> Summary
> -------
> 
> This patch adds an SQLite 3 realtime driver. It supports multiple databases, ast_realtime_require (warn, createclose, and createchar support including the ability to create missing tables), static realtime, and batching commits in transactions to increase write performance. It currently caches no table data, but I figure that premature optimization is bad anyway.
> 
> It, like other realtime drivers, doesn't escape data when building the SQL strings. I started out using parameter binding, but SQLite doesn't let you bind column names, so given how dynamic everything with realtime is, I just when with building the statements outright. I could manually escape the parameters, but the only thing in the SQLite 3 library I could find that does that dynamically allocates the string and that ends up being a lot of little allocs and frees. I suppose we could write our own using a single ast_str with some ast_str_reset calls between each one, but it is a bit of a pain. Until we want to open up the realtime api to things like AMI where user-generated input is going to be a problem, escaping isn't really necessary.
> 
> The impetus for writing this is that Asterisk now has a built-in SQLite 3 database which the astdb uses. The next step would be to convert the astdb to using the realtime calls, thus making it possible for it to be used with any realtime backend (but using the default SQLite 3 db unless configured otherwise). After that, we can start rewriting some things that use the astdb in very crude ways to start using realtime calls to the internal (or external, if configured that way) databases so that the data can be stored in more logical ways than a key/value store allows.
> 
> 
> Diffs
> -----
> 
>   /trunk/res/res_config_sqlite3.c PRE-CREATION 
>   /trunk/configs/res_config_sqlite3.conf.sample PRE-CREATION 
> 
> Diff: https://reviewboard.asterisk.org/r/1408/diff
> 
> 
> Testing
> -------
> 
> Verified that static realtime extensions.conf loads properly. Realtime CLI commands all behave as expected. Tested unload/load and reload scenarios making sure that they behaved as expected and that there were no ref/memory leaks. Made sure that batching worked.
> 
> Once we move the astdb to using realtime calls, the existing unit tests for that should give a workout to the realtime driver as well. I didn't write a new test pointing to the astdb because the astdb locks its database so it cannot be written to from another connection.
> 
> 
> Thanks,
> 
> Terry
> 
>

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