Add HTTP debug header, #593

[Thegennok]

As requested in #593, there is now the memory comsuption and the time elapsed in a HTTP header if perf_debug is true

[mention-bot]

By analyzing the blame information on this pull request, we identified @pascalchevrel, @TheoChevalier and @flodolo to be potential reviewers

[flodolo]

Since the code is basically the same of logScriptPerformances, I think it makes more sense to only keep one function and pass a parameter to ask to log info in error_log, header, or both

[flodolo]

No need for an extra space before the semicolon.
nit for the description: http header -> HTTP header

[Thegennok]

He log in error_log and HTTP header in the same time now.

[flodolo]

Unfortunately this generates an error in the log:

PHP Warning:  Cannot modify header information - headers already se
nt by (output started at /home/flodolo/github/transvision/app/views/templates/base.php:162) in /home/flodolo/github/transvision/app/classes/Transvision/
Utils.php on line 363, referer: xxx

It should be OK to move the call from dispatcher to the base template (but need to be verified thoroughly)

[pascalchevrel]

This is too simplistic an approch :)
We need all views to output that perf http header and we need to send that header before the real content otherwise we get an error about headers already sent.

The right approach is to split the function in 3:
getScriptPerformances() that returns an array of raw data
logScriptPerformances() that does what it does now but gets the data from getScriptPerformances()
outputPerformancesHHeader() that outputs the header and also gets the data from getScriptPerformances()

Then in the dispatcher, we use output buffering and at the end of the dispatcher, we print the buffers like that:

print $perf_header . $content;

That's actually moving what we do in base.php to the dispatcher.
The json view should also be updated to not die and only print.

I have a working patch so maybe I could take the bug.

[flodolo]

Replaced by #637