From d317164aeb43cd96db03023733ebe658e55c381e Mon Sep 17 00:00:00 2001
From: Alex Monk <krenair@gmail.com>
Date: Mon, 23 Mar 2015 21:32:28 +0000
Subject: [PATCH] Collect only 25% of WikiEditor events

By checking the first character of our session ID (which is just a random
hex digit)

Bug: T93201
Change-Id: If1f7e7c4da6c3f37533a6feba56ff6422f5b9750
---
 WikiEditor.hooks.php | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/WikiEditor.hooks.php b/WikiEditor.hooks.php
index 59c1cf2a..accff510 100644
--- a/WikiEditor.hooks.php
+++ b/WikiEditor.hooks.php
@@ -154,6 +154,10 @@ class WikiEditorHooks {
 		if ( !class_exists( 'EventLogging' ) ) {
 			return false;
 		}
+		// Sample 25% (via hex digit)
+		if ( $data['editingSessionId'][0] > '3' ) {
+			return false;
+		}
 
 		$user = $article->getContext()->getUser();
 		$page = $article->getPage();
@@ -257,6 +261,11 @@ class WikiEditorHooks {
 		if ( !$editingStatsId ) {
 			$editingStatsId = self::getEditingStatsId();
 		}
+		// Sample 25% (via hex digit)
+		if ( $editingStatsId[0] > '3' ) {
+			return true;
+		}
+
 		$outputPage->addHTML(
 			Xml::element(
 				'input',