From 4ee9063956ba1a3e7fcc1195b5034f128267ab35 Mon Sep 17 00:00:00 2001
From: Ori Livneh <ori@wikimedia.org>
Date: Thu, 4 Sep 2014 16:56:20 -0700
Subject: [PATCH] Under HHVM, measure resources for the thread, not calling
 process

As of <https://github.com/facebook/hhvm/commit/0f98cab>, it is possible to
call getrusage( [ int $who = 0 ] ) with $who = 2 to request resource usage
info for the current thread (RUSAGE_THERAD), rather than the calling process
(RUSAGE_SELF). (Earlier versions of HHVM return RUSAGE_SELF data unless $who
is 1.)

PHP5 code can assume that each request is handled in a dedicated subprocess,
but the same is not true of HHVM, which is multi-threaded. Therefore, to get
resource usage data for the current request context, it is necessary to ask
for RUSAGE_THREAD rather than RUSAGE_SELF.

To do this, introduce a new global function in Profiler.php: wfGetRusage().
It is defined there and not in GlobalFunctions.php so that it can be used early
in WebStart.php.

Bug: 70227
Change-Id: Ibe9598ecdfc0f6c434f8b3c7a94f06a7b2fcca23
---
 includes/WebStart.php            |  9 ++++-----
 includes/parser/ParserOutput.php | 10 ++++++----
 includes/profiler/Profiler.php   | 23 ++++++++++++++++++++---
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/includes/WebStart.php b/includes/WebStart.php
index e137628c5e..2ae72dcc00 100644
--- a/includes/WebStart.php
+++ b/includes/WebStart.php
@@ -40,8 +40,6 @@ if ( ini_get( 'register_globals' ) ) {
 header( 'X-Content-Type-Options: nosniff' );
 
 $wgRequestTime = microtime( true );
-# getrusage() does not exist on the Microsoft Windows platforms, catching this
-$wgRUstart = function_exists( 'getrusage' ) ? getrusage() : array();
 unset( $IP );
 
 # Valid web server entry point, enable includes.
@@ -60,11 +58,12 @@ if ( $IP === false ) {
 	$IP = realpath( '.' ) ?: dirname( __DIR__ );
 }
 
-# Start the autoloader, so that extensions can derive classes from core files
-require_once "$IP/includes/AutoLoader.php";
-
 # Load the profiler
 require_once "$IP/includes/profiler/Profiler.php";
+$wgRUstart = wfGetRusage() ?: array();
+
+# Start the autoloader, so that extensions can derive classes from core files
+require_once "$IP/includes/AutoLoader.php";
 
 # Load up some global defines.
 require_once "$IP/includes/Defines.php";
diff --git a/includes/parser/ParserOutput.php b/includes/parser/ParserOutput.php
index f939de35bb..cca6048a0f 100644
--- a/includes/parser/ParserOutput.php
+++ b/includes/parser/ParserOutput.php
@@ -733,10 +733,12 @@ class ParserOutput extends CacheTime {
 		if ( !$clock || $clock === 'wall' ) {
 			$ret['wall'] = microtime( true );
 		}
-		if ( ( !$clock || $clock === 'cpu' ) && function_exists( 'getrusage' ) ) {
-			$ru = getrusage();
-			$ret['cpu'] = $ru['ru_utime.tv_sec'] + $ru['ru_utime.tv_usec'] / 1e6;
-			$ret['cpu'] += $ru['ru_stime.tv_sec'] + $ru['ru_stime.tv_usec'] / 1e6;
+		if ( !$clock || $clock === 'cpu' ) {
+			$ru = wfGetRusage();
+			if ( $ru ) {
+				$ret['cpu'] = $ru['ru_utime.tv_sec'] + $ru['ru_utime.tv_usec'] / 1e6;
+				$ret['cpu'] += $ru['ru_stime.tv_sec'] + $ru['ru_stime.tv_usec'] / 1e6;
+			}
 		}
 		return $ret;
 	}
diff --git a/includes/profiler/Profiler.php b/includes/profiler/Profiler.php
index 7b8f340bab..418b5d48b6 100644
--- a/includes/profiler/Profiler.php
+++ b/includes/profiler/Profiler.php
@@ -20,9 +20,26 @@
  * @file
  * @ingroup Profiler
  * @defgroup Profiler Profiler
- * This file is only included if profiling is enabled
  */
 
+/**
+ * Get system resource usage of current request context.
+ * Invokes the getrusage(2) system call, requesting RUSAGE_SELF if on PHP5
+ * or RUSAGE_THREAD if on HHVM. Returns false if getrusage is not available.
+ *
+ * @since 1.24
+ * @return array|bool Resource usage data or false if no data available.
+ */
+function wfGetRusage() {
+	if ( !function_exists( 'getrusage' ) ) {
+		return false;
+	} elseif ( defined ( 'HHVM_VERSION' ) ) {
+		return getrusage( 2 /* RUSAGE_THREAD */ );
+	} else {
+		return getrusage( 0 /* RUSAGE_SELF */ );
+	}
+}
+
 /**
  * Begin profiling of a function
  * @param string $functionname Name of the function we will profile
@@ -272,10 +289,10 @@ abstract class Profiler {
 	 */
 	protected function getTime( $metric = 'wall' ) {
 		if ( $metric === 'cpu' || $metric === 'user' ) {
-			if ( !function_exists( 'getrusage' ) ) {
+			$ru = wfGetRusage();
+			if ( !$ru ) {
 				return 0;
 			}
-			$ru = getrusage();
 			$time = $ru['ru_utime.tv_sec'] + $ru['ru_utime.tv_usec'] / 1e6;
 			if ( $metric === 'cpu' ) {
 				# This is the time of system calls, added to the user time
-- 
2.20.1