From: John Torjo (john.lists_at_[hidden])
Date: 2005-05-19 11:39:20
Gennadiy Rozental wrote:
>>What about this:
>>
>>time_t slow_time()
>>{
>> BOOST_LOG(x) << "going to sleep at " << time(0);
>> sleep(1);
>> time_t t;
>> BOOST_LOG(x) << "waking up at " << t = time(0);
>> return t;
>>}
>>
>>void f()
>>{
>> BOOST_LOG(x) << "slow_time returned " << slow_time() << " then " <<
>>slow_time();
>>}
>>
>>Resulting in (I ran this test a long time ago, boot time isn't bad either
>>:-) :
>>
>>going to sleep at 0
>>waking up at 1
>>going to sleep at 1
>>waking up at 2
>>slow time returned 1 then 2
>
>
> I have several questions about this:
>
> 1. How do you know in general which log present trace of first invocation,
> and which one second:
>
> void acess_db( ... ) {
> if( some error )
> log << "invalid account key" << key;
> }
>
> int get_balance(...){
> ...
> if( !access_db(...) )
> return 0;
> }
>
> ...
>
> log << "Mary has balance: " << get_balance() << " and John has balance: " <<
> get_balance()
>
I would assume you meant something like:
log << "Mary has balance: " << get_balance("mary") << " and John has
balance: " << get_balance("john");
If so, when you have a bad key, you should have some extra information
to log (the name, or something).
>
> 2. How does the log system know when to dump the cash? Does it
introduce any scope guards?
Have you actually taken a look at the code? A temporary variable is
created, and in its destructor I perform the logging.
>
> 4. What kind of overhead it introduces? Now instead of directly
writing into
> stream we keep second copy of every piece of log essentially doubling
the
> memory usage and increasing log overhead, isn't it?
>
Have you actually tested it in a multi-threading environment, or is this
just your guts?
Best,
John
-- John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -v1.6.3 (Resource Splitter) -- http://www.torjo.com/cb/ - Click, Build, Run!