patcht9501: Skip testing load if we can't detect it

> Currently gitweb only knows how to check for load using /proc/loadavg,
> which isn't available on all systems.  We shouldn't fail the test just
> because we don't know how to check the system load.
> 
> Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>

> ---
>  t/t9501-gitweb-standalone-http-status.sh |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/t/t9501-gitweb-standalone-http-status.sh b/t/t9501-gitweb-standalone-http-status.sh
> index 7590f10..992d729 100755
> --- a/t/t9501-gitweb-standalone-http-status.sh
> +++ b/t/t9501-gitweb-standalone-http-status.sh
> @@ -115,12 +115,19 @@ test_debug 'cat gitweb.output'
>  # ----------------------------------------------------------------------
>  # load checking
>  
> +if test -e /proc/loadavg
> +then
> +	test_set_prereq PROC_LOADAVG
> +else
> +	say 'skipping load tests (no /proc/loadavg found)'
> +fi
> +
>  # always hit the load limit
>  cat >>gitweb_config.perl <<\EOF
>  our $maxload = 0;
>  EOF
>  
> -test_expect_success 'load checking: load too high (default action)' '
> +test_expect_success PROC_LOADAVG 'load checking: load too high (default action)' '
>  	gitweb_run "p=.git" &&
>  	grep "Status: 503 Service Unavailable" gitweb.headers &&
>  	grep "503 - The load average on the server is too high" gitweb.body
> -- 
> 1.7.0.rc1.141.gd3fd2
> 

> Brian Gernhardt <brian@gernhardtsoftware.com> writes:
> 
>> Currently gitweb only knows how to check for load using /proc/loadavg,
>> which isn't available on all systems.  We shouldn't fail the test just
>> because we don't know how to check the system load.
>> 
>> Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>
> 
> NAK.  It is not necessary, and it would be hindrance (one more place
> to update) if we are to extend get_loadavg() in gitweb to work without
> /proc/loadavg, e.g. via BSD::loadavg module.

> Third, the test (as you can see below in context line in quoted diff
> below) forces gitweb to go over maximum load by setting $maxload to 0.
> This means that regardless of true load, and regardless whether gitweb
> can detect system load (remember that if it cant get system load it
> returns 0 instead) gitweb would be in "load too high" situation.

> On Feb 6, 2010, at 6:22 AM, Jakub Narebski wrote:
>> Brian Gernhardt <brian@gernhardtsoftware.com> writes:
>> 
>>> Currently gitweb only knows how to check for load using /proc/loadavg,
>>> which isn't available on all systems.  We shouldn't fail the test just
>>> because we don't know how to check the system load.
>>> 
>>> Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>
>> 
>> NAK.  It is not necessary, and it would be hindrance (one more place
>> to update) if we are to extend get_loadavg() in gitweb to work without
>> /proc/loadavg, e.g. via BSD::loadavg module.
> 
> Without this patch, the test fails on my OS X machine (which doesn't
> have /proc).  So _something_ is necessary.

>> Third, the test (as you can see below in context line in quoted diff
>> below) forces gitweb to go over maximum load by setting $maxload to 0.
>> This means that regardless of true load, and regardless whether gitweb
>> can detect system load (remember that if it cant get system load it
>> returns 0 instead) gitweb would be in "load too high" situation.
> 
> I did check the code.  Skipping the test seemed more in line with other tests.
> 
> sub get_loadavg {
>     if( -e '/proc/loadavg' ){}
>     return 0;
> }
> 
> if (defined $maxload && get_loadavg() > $maxload) {
> }
> 
> Setting $maxload to 0 does _not_ trigger failure because zero is not
> greater than 0.  Setting $maxload to -1 might work though.  I'll try
> it and test it in a little bit.  While I disagree that it's a good
> way to handle the situation, I will see if it works.   

> The code to check for load returns 0 if it doesn't know how to find
> load.  It also checks to see if the current load is higher than the
> max load.  So to force the script to quit early by setting the maxload
> variable negative which should work for systems where we can detect
> load (which should be a positive number) and systems where we can't
> (where detected load is 0)
> 
> Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>

> or the test should use 
>
>   $maxload = -1;
>
> to artificially force 'load too high' situation.

> Here is my attempt to reword the commit log message from Brian (the  
> "-1"
> one, squashed into a revert of the one from yesterday, the latter of  
> which
> I already pushed out).  I just added the first paragraph to better  
> justify
> the reason why we are testing the codepath that would never be  
> exercised
> in real life on platforms that lack /proc/loadavg.

>    Subject: t9501: Re-fix max load test
>
>    Revert the previous attempt to skip this test on platforms where we
>    currently cannot determine the system load.  We want to make sure  
> that
>    the max-load-limit codepath produces results cleanly, when gitweb  
> is
>    updated and becomes capable of reading the load average by some  
> other
>    method.
>
>    The code to check for load returns 0 if it doesn't know how to find
>    load.  It also checks to see if the current load is higher than the
>    max load.  So to force the script to quit early by setting the  
> maxload
>    variable negative which should work for systems where we can detect
>    load (which should be a positive number) and systems where we can't
>    (where detected load is 0)
>
>    Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>