Re: [boost] Circular log buffer

From: John Torjo (john.lists_at_[hidden])
Date: 2004-10-28 12:52:26

Darren Cook wrote:

> I'm finding an increasing need for an in-file memory log: specifically 
> when my program asserts I want to see where it has been.
> 
> There are two problems with normal logging, i.e. appending to a disk file:
>   * The files get very, very big (I've filled my home partition before)
>   * All that writing to disk slows the application down noticeably.
> 
> I checked log4cpp and John Torjo's logging library and neither seem to 

not yet, but in the near future I want to add cyclic logs (or rotating 
logs, if you wish).

Note:
You can use ts_appender() (formely known as ts_write()), and thus the 
writing will be on a dedicated thread (I've used this in a real-life 
app. - it's *very* fast).

Just for fun, something like:
// assume you've BOOST_DEFINE_LOG(gui,"app.gui") somewhere
add_appender("app.gui", ts_appender(write_to_file("out.txt")) );

// written to file in its own dedicated thread - very fast
BOOST_LOG(gui) << "whatever" << " you " << "want";

But for asserts, this is not useful :(

> offer this, but it seems it could fit as one of the logging targets. I 
> had in mind an object that is a wrapper for e.g. a 1Mb char buffer with 
> the same interface as std::ostream, so I can just write:
>    log_buffer<<"In func1, x="<<x<<", obj="<<obj<<"\n";
> 
> And then when my program asserts I can pass log_buffer as a parameter to 
> be output (requires it to have operator<< defined):
>    SMART_ASSERT(y!=1)(y)(log_buffer);

As a side-note, I'm planning to update the SMART_ASSERT lib in about 3 
weeks ;)
At that time, I want to make it interoperate with Boost.Log .
Thus, you should have your failed asserts in no time ;)

However, the fact you want the circular log buffer makes me think that 
you have quite a few failed assertions ;)
Anyway, I'll try to improve SMART_ASSERT in the near future.
(now that I think about it, maybe it should use Boost.Log for its 
logging completely...)

Best,
John

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John Torjo,    Contributing editor, C/C++ Users Journal
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