From: Olav Sandstaa
Date: March 10 2009 9:46am
Subject: Re: Proposal: extension to Log interface to get error message written
 independently of falcon-debug-mask
List-Archive: http://lists.mysql.com/falcon/605
Message-Id: <49B63706.3040301@sun.com>
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Hi,

I have now implement this functionality. The main added functionality to 
the Log class is:

1. A new debug mask called LogFatalError:

This debug mask will be on by default for the Falcon log. It will not
be disabled if the user provides a debug mask at startup or changes the 
debug mask for a running server.

2. A new log method Log::fatal():

Log messages written using this method will always be written to
Falcon/MySQL's log file.

Note that compare to my original proposal this debug mask will only be 
on for the  original Falcon logger (StorageInterface::logger), not for 
the "MySQL logger" (StorageInterface::mysqlLogger). Due to this the 
default log mask is not completely maintained inside the Log class but 
has to be set in when the Falcon logger is added to listen to the log 
(in ha_falcon.cpp).

The patch is available here:

   http://lists.mysql.com/commits/68742

It would be great if someone could have a look at the patch and either 
give feedback or an OK to push it.

Thanks,
Olav


Jim Starkey wrote:
> Olav Sandstaa wrote:
>>
>> Based on the discussion we have had by email about writing to MySQL's 
>> error log file and my need for always getting the error message about 
>> problems to the serial log written independently of what the status 
>> of the --falcon-debug-mask is, I propose following extention to the 
>> Log:: interface:
>>
>> Alterantive 1 (based on Ann's suggestions in an earlier email):
>> ===========
>>
>> * Introduce a new log category called "Fatal" (or something similar) 
>> that always get written to the error log independently of what the 
>> user has specified in the --falcon-debug-mask.
>> * Example:
>>
>>       Log::log(Fatal, "This text will always go to the error log 
>> file\n");
>>
>>    Note: This log category will possibly be documented in the MySQL 
>> documentation along with the others, but the user not be allowed to 
>> turn it off if she sets a debug-mask that does not enable it.
>>
>> Alternative 2:
>> ==========
>>
>>  * Extend the Log:: interface with a new method called fatal() (or 
>> error()) that will always write the message to the error log file
>>  * Example:
>>
>>      Log::fatal("This text will always go to the error log file, and 
>> by the way Falcon has just crashed\n");
>>
>>      or
>>
>>      Log::error("This text will always go to the error log file, and 
>> by the way Falcon has just crashed\n");
>>
>>  * "Advantage" of this is that it does not interfere with the 
>> falcon-debug-mask and the user visibility of this.
>>
>> Any strong preference for any of these? Any feedback or other 
>> suggestions?
>>
>> PS: This is not about printf and clashes with the server's log 
>> writing, it is just to define an interface that can be used for 
>> messages that we want to get out with having the user needing to 
>> specify an appropriate debug flag .
>>
>> Regards,
>> Olav
>>
>> PS A bonus proposal: I consider removing the implementation of 
>> Log::print() as it uses printf directly if there is no particular use 
>> for it (I do not think it is used anywhere)
>>
>>
>>
>>
> The two alternative are not mutually exclusive.  The primary mechanism 
> is a new message class "Fatal".  There is also a secondary convenience 
> method Log::fatal(const char*, ...) that logs the message with that 
> bit in a manner analogous to Log::debug(const char*, ...).
>