From 2a690c54eebdcba39967db34caee2bc6dee640b5 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim=20D=C3=BCsterhus?= <timwolla@googlemail.com>
Date: Sun, 7 Oct 2018 13:17:19 +0200
Subject: [PATCH] Append REQUEST_URI to database queries (#2729)

* Append REQUEST_URI to database queries

This might come in handy to debug long running queries in
production.

Idea stolen from: https://chris-lamb.co.uk/projects/django-append-url-to-sql

* Add ENABLE_PRODUCTION_DEBUG_MODE option

* Save a substr() if ENABLE_PRODUCTION_DEBUG_MODE is off
---
 com.woltlab.wcf/option.xml                      |  5 +++++
 .../lib/system/database/Database.class.php      | 17 ++++++++++++++++-
 wcfsetup/install/lang/de.xml                    |  2 ++
 wcfsetup/install/lang/en.xml                    |  2 ++
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/com.woltlab.wcf/option.xml b/com.woltlab.wcf/option.xml
index 0e4f78b18c..00c6364239 100644
--- a/com.woltlab.wcf/option.xml
+++ b/com.woltlab.wcf/option.xml
@@ -411,6 +411,11 @@
 				<optiontype>boolean</optiontype>
 				<defaultvalue>0</defaultvalue>
 			</option>
+			<option name="enable_production_debug_mode">
+				<categoryname>module.development</categoryname>
+				<optiontype>boolean</optiontype>
+				<defaultvalue>1</defaultvalue>
+			</option>
 			<option name="enable_benchmark">
 				<categoryname>module.development</categoryname>
 				<optiontype>boolean</optiontype>
diff --git a/wcfsetup/install/files/lib/system/database/Database.class.php b/wcfsetup/install/files/lib/system/database/Database.class.php
index ae412051bc..d9c7af4d39 100644
--- a/wcfsetup/install/files/lib/system/database/Database.class.php
+++ b/wcfsetup/install/files/lib/system/database/Database.class.php
@@ -240,7 +240,22 @@ abstract class Database {
 		$statement = $this->handleLimitParameter($statement, $limit, $offset);
 		
 		try {
-			$pdoStatement = $this->pdo->prepare($statement);
+			// Append routing information of the current request as a comment.
+			// This allows the system administrator to find offending requests
+			// in MySQL's slow query log and / or MySQL's process list.
+			// Note: This is meant to be run unconditionally in production to be
+			//       useful. Thus the code to retrieve the request information
+			//       must be absolutely lightweight.
+			$requestInformation = '';
+			if (ENABLE_PRODUCTION_DEBUG_MODE && isset($_SERVER['REQUEST_URI'])) {
+				$requestInformation = substr($_SERVER['REQUEST_URI'], 0, 90);
+				if (isset($_REQUEST['className']) && isset($_REQUEST['actionName'])) {
+					$requestInformation .= ' ('.$_REQUEST['className'].':'.$_REQUEST['actionName'].')';
+				}
+				$requestInformation = substr($requestInformation, 0, 180);
+			}
+			
+			$pdoStatement = $this->pdo->prepare($statement.($requestInformation ? " -- ".$this->pdo->quote($requestInformation) : ''));
 			
 			return new $this->preparedStatementClassName($this, $pdoStatement, $statement);
 		}
diff --git a/wcfsetup/install/lang/de.xml b/wcfsetup/install/lang/de.xml
index a1b42b2478..ad47dcc7ff 100644
--- a/wcfsetup/install/lang/de.xml
+++ b/wcfsetup/install/lang/de.xml
@@ -1162,6 +1162,8 @@
 		<item name="wcf.acp.option.show_version_number"><![CDATA[Versionsnummer der Software im Copyright-Hinweis anzeigen]]></item>
 		<item name="wcf.acp.option.enable_debug_mode"><![CDATA[Debug-Modus aktivieren]]></item>
 		<item name="wcf.acp.option.enable_debug_mode.description"><![CDATA[Aktiviert ausführliche Fehlerberichte. Diese Option sollte im Live-Betrieb abgeschaltet werden.]]></item>
+		<item name="wcf.acp.option.enable_production_debug_mode"><![CDATA[Problemanalyse im Live-Betrieb]]></item>
+		<item name="wcf.acp.option.enable_production_debug_mode.description"><![CDATA[Hängt die aktuelle URL an Datenbankabfragen an, um diese im Log des Datenbankservers einfacher identifizieren zu können.]]></item>
 		<item name="wcf.acp.option.external_link_rel_nofollow"><![CDATA[Externe Links mit dem Attribut „rel="nofollow"“ versehen]]></item>
 		<item name="wcf.acp.option.external_link_rel_nofollow.description"><![CDATA[Das Attribut „rel="nofollow"“ weist Suchmaschinen an, einen bestimmten Link auf einer Seite zu ignorieren.]]></item>
 		<item name="wcf.acp.option.external_link_target_blank"><![CDATA[Externe Links in neuem Fenster öffnen]]></item>
diff --git a/wcfsetup/install/lang/en.xml b/wcfsetup/install/lang/en.xml
index 8c49ecb8cd..7cd0a940b0 100644
--- a/wcfsetup/install/lang/en.xml
+++ b/wcfsetup/install/lang/en.xml
@@ -1144,6 +1144,8 @@
 		<item name="wcf.acp.option.show_version_number"><![CDATA[Display version number in copyright notice]]></item>
 		<item name="wcf.acp.option.enable_debug_mode"><![CDATA[Enable debug mode]]></item>
 		<item name="wcf.acp.option.enable_debug_mode.description"><![CDATA[Enables extensive error messages, it should always be disabled in production environments!]]></item>
+		<item name="wcf.acp.option.enable_production_debug_mode"><![CDATA[Problem analysis in production environments]]></item>
+		<item name="wcf.acp.option.enable_production_debug_mode.description"><![CDATA[Appends the current URL to database queries to assist looking them up in the database server’s log files.]]></item>
 		<item name="wcf.acp.option.external_link_rel_nofollow"><![CDATA[Append the attribute “rel="nofollow"” to all external links]]></item>
 		<item name="wcf.acp.option.external_link_rel_nofollow.description"><![CDATA[The attribute “rel="nofollow"” tells search engines to disregard external links.]]></item>
 		<item name="wcf.acp.option.external_link_target_blank"><![CDATA[Open external links in a new window]]></item>
-- 
2.20.1