<div>On Sat, Apr 2, 2011 at 11:10 AM, Michael Snoyman <span dir="ltr"><<a href="mailto:michael@snoyman.com">michael@snoyman.com</a>></span> wrote:</div><div><div><div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
@Sven: I agree, database level logging is a *very* nice idea. Timing<br>
could also be very useful. The former will require modifications to<br>
persistent; let's try to think about how that would work (I don't have<br>
any clear ideas immediately). For timing: we could add a nice<br>
combinator on top of the main logging functions:<br>
<br>
logTimed :: MonadIO m => (normal params) -> m a -> m a<br>
logTimed (normal params) action = do<br>
begin <- getCurrentTime<br>
a <- action<br>
end <- getCurrentTime<br>
log (normal params) ++ "; operation took: " ++ show (end - begin)<br>
return a<br>
<br>
@Max: I'm not planning on adding a specific backend like hslogger. I'd<br>
rather make a system that is flexible enough to allow a user to plug<br>
in whatever backend he/she wants. Plus, hslogger in LGPL, which I'm<br>
trying to avoid in yesod-core.<br>
<br>
@Greg: I like the idea of adding source. How would you see this, just<br>
another Text argument? As for typeclass/not typeclass: the advantage<br>
to the former is that all subsites will get to piggy-back on what the<br>
master site defines. So I *definitely* think it's worthwhile.<br>
<font color="#888888"><br></font></blockquote><div> </div><div>in hslogger the source is just another string. That makes it easily extensible, but the lack of type safety worries me a bit. Maybe we just need to trust everyone to use a single canonical (Text) string for their sources. I imagine that for any source one would create a helper function that applies the source Text argument. Likewise, the default logging function for Yesod users wouldn't have a source argument.</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><font color="#888888">
Michael<br>
</font><div><div></div><div class="h5"><br>
On Sat, Apr 2, 2011 at 5:48 PM, Greg Weber <<a href="mailto:greg@gregweber.info">greg@gregweber.info</a>> wrote:<br>
> I like Michael's straw man. The only missing aspect I see is specifying a<br>
> source. hslogger has this capability. This is useful for a web framework to<br>
> differentiate between database logging and request logging, etc. It can be<br>
> useful for an application when it grows in size.<br>
> Does logging need to be in the typeclass or does it make send to just import<br>
> it?<br>
> On Sat, Apr 2, 2011 at 3:22 AM, Max Cantor <<a href="mailto:mxcantor@gmail.com">mxcantor@gmail.com</a>> wrote:<br>
>><br>
>> Take a look at hslogger. I know that another dependency is low on the<br>
>> "things we want" list, but its pretty decent.<br>
>><br>
>> max<br>
>><br>
>> On Apr 1, 2011, at 3:18 PM, Sven Koschnicke (GFXpro) wrote:<br>
>><br>
>> > Hello,<br>
>> ><br>
>> > I would add a log level "Debug" which only gets printed to the log when<br>
>> > in development mode. I also found the log output of SQL queries generated by<br>
>> > the database layer quite helpful in development. Another thing is<br>
>> > performance measurements, the time it takes to answer an request. These<br>
>> > ideas are all coming from the way RoR does logging, but I found it very<br>
>> > helpful when developing with Rails, so it should be a nice feature in Yesod,<br>
>> > too. Here is an example:<br>
>> ><br>
>> > Instrument Load (0.4ms) SELECT * FROM "instruments" WHERE<br>
>> > ("instruments"."id" = 86) ORDER BY LOWER(<a href="http://instruments.name" target="_blank">instruments.name</a>)<br>
>> > Rendered overview/_notification (2.1ms)<br>
>> > CACHE (0.0ms) SELECT * FROM "instruments" WHERE ("instruments"."id" =<br>
>> > 86) ORDER BY LOWER(<a href="http://instruments.name" target="_blank">instruments.name</a>)<br>
>> > Rendered overview/_notification (1.5ms)<br>
>> > CACHE (0.0ms) SELECT * FROM "instruments" WHERE ("instruments"."id" =<br>
>> > 90) ORDER BY LOWER(<a href="http://instruments.name" target="_blank">instruments.name</a>)<br>
>> > Rendered overview/_notification (1.4ms)<br>
>> > CACHE (0.0ms) SELECT * FROM "instruments" WHERE ("instruments"."id" =<br>
>> > 62) ORDER BY LOWER(<a href="http://instruments.name" target="_blank">instruments.name</a>)<br>
>> > Rendered overview/_notification (1.5ms)<br>
>> > DepotGroup Load (27.2ms) SELECT * FROM "depot_groups" ORDER BY<br>
>> > ordinal<br>
>> > Completed in 3530ms (View: 166, DB: 2051) | 200 OK [<a href="http://localhost/" target="_blank">http://localhost/</a>]<br>
>> ><br>
>> ><br>
>> > Sven<br>
>> ><br>
>> > On 04/01/2011 08:20 AM, Michael Snoyman wrote:<br>
>> >> Hi all,<br>
>> >><br>
>> >> Hot on the heels of the decision to remove logging from WAI, I would<br>
>> >> like to add it to Yesod. I think (at least to start with), we really<br>
>> >> need two modifications: a new method in the Yesod typeclass that<br>
>> >> specifies what to do with log messages, and a function living in the<br>
>> >> Handler monad that calls that method. I do not have any strong<br>
>> >> opinions on this topic, so I would appreciate input. Here's a strawman<br>
>> >> proposal:<br>
>> >><br>
>> >> data LogLevel = LevelInfo | LevelWarn | LevelError | LevelOther Text<br>
>> >><br>
>> >> class Yesod a where<br>
>> >> messageLogger :: a -> LogLevel -> Text -> IO ()<br>
>> >> messageLogger _ level msg = formatLogMessage level msg>>=<br>
>> >> Data.Text.Lazy.IO.hPutStrLn System.IO.stderr<br>
>> >><br>
>> >> formatLogMessage :: LogLevel -> Text -> IO Text<br>
>> >> formatLogMessage = ...<br>
>> >> -- print timestamp, log level, message, maybe process ID? to stderr<br>
>> >> -- make sure to expose the<br>
>> >><br>
>> >> logInfo :: MonadIO m => Text -> GGHandler sub master m ()<br>
>> >> logInfo t = do<br>
>> >> y< getYesod<br>
>> >> liftIO $ messageLogger y LevelInfo t<br>
>> >><br>
>> >> ... and so on and so forth<br>
>> >><br>
>> >> This should give completely flexibility to users to send their logs<br>
>> >> anywhere (database, printer, missiles) and in whatever format they<br>
>> >> want.<br>
>> >><br>
>> >> Other ideas:<br>
>> >><br>
>> >> * It would be nice to include file/line number information, but I'm<br>
>> >> not sure how easy/possible that will be without requiring the user to<br>
>> >> manually enter CPP macros.<br>
>> >> * Actually, that was my only other idea :)<br>
>> >><br>
>> >> Michael<br>
>> >><br>
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>> ><br>
>> ><br>
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</div></div></blockquote></div><br></div></div></div>