profiler: Add ProfilingContext class

Use this class to track the entry point and handler used for requests,
making it available for use in profiling, stats, and logging code.

This makes it possible for periodic and/or shutdown profiling callbacks
to know the basic action handler that applies to the request (if any).
Metric names can easily include this string along with MW_ENTRY_POINT
to create per-action profiling dashboards.

This info cannot otherwise be acquired from things like excimer stack
traces since the router and handler classes do not appear in the stack
during PRESEND deferred updates and variations like ApiMain/SpecialPage
"inclusion mode" would have to be detected somehow.

Bug: T330810
Change-Id: Icca5a7a343faeeb18652994c96752acb61a61fd1

1 files changed, 2 insertions, 0 deletions

diff --git a/includes/ResourceLoader/ResourceLoader.php b/includes/ResourceLoader/ResourceLoader.php
index ad46ddd35c86..492fff773303 100644
--- a/includes/ResourceLoader/ResourceLoader.php
+++ b/includes/ResourceLoader/ResourceLoader.php
@@ -37,6 +37,7 @@ use MediaWiki\HookContainer\HookContainer;
 use MediaWiki\Html\Html;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
+use MediaWiki\Profiler\ProfilingContext;
 use MediaWiki\Request\HeaderCallback;
 use MediaWiki\Title\Title;
 use MediaWiki\User\UserOptionsLookup;
@@ -750,6 +751,7 @@ class ResourceLoader implements LoggerAwareInterface {
 		ob_start();
 
 		$responseTime = $this->measureResponseTime();
+		ProfilingContext::singleton()->init( MW_ENTRY_POINT, 'respond' );
 
 		// Find out which modules are missing and instantiate the others
 		$modules = [];