From: Adrian Lang <adrian.heine@wikimedia.de>
Date: Tue, 27 Oct 2015 13:47:38 +0000 (+0000)
Subject: Revert "Enforce stricter slave lag limits for bot API requests"
X-Git-Tag: 1.31.0-rc.0~9209^2
X-Git-Url: https://git.cyclocoop.org/%27.%24link.%27?a=commitdiff_plain;h=25aeee58af52fc84d2780df910083a735c6fbaa6;p=lhc%2Fweb%2Fwiklou.git

Revert "Enforce stricter slave lag limits for bot API requests"

This broke most Wikidata API PHPUnit tests.

This reverts commit dc10216e77b06b0fc7bb5e0824eb0967129c2e1f.

Change-Id: I19285ff0eddffb38cdbf45bbd05ba2d8a1816b41
---

diff --git a/RELEASE-NOTES-1.27 b/RELEASE-NOTES-1.27
index f3f0704d25..f8293b975b 100644
--- a/RELEASE-NOTES-1.27
+++ b/RELEASE-NOTES-1.27
@@ -63,8 +63,6 @@ production.
   setting in the relevant section of $wgLBFactoryConf.
 * User::newSystemUser() may be used to simplify the creation of passwordless
   "system" users for logged actions from scripts and extensions.
-* $wgAPIMaxLagThreshold was added to limit bot changes when databases lag
-  becomes too high.
 
 ==== External libraries ====
 
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 310b241bc1..04f3f31789 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -7323,13 +7323,6 @@ $wgAPIMaxResultSize = 8388608;
  */
 $wgAPIMaxUncachedDiffs = 1;
 
-/**
- * Maximum amount of DB lag on a majority of DB slaves to tolerate
- * before forcing bots to retry any write requests via API errors.
- * This should be lower than the 'max lag' value in $wgLBFactoryConf.
- */
-$wgAPIMaxLagThreshold = 7;
-
 /**
  * Log file or URL (TCP or UDP) to log API requests to, or false to disable
  * API request logging
diff --git a/includes/api/ApiMain.php b/includes/api/ApiMain.php
index f60f5df6e9..c641c9513c 100644
--- a/includes/api/ApiMain.php
+++ b/includes/api/ApiMain.php
@@ -1002,6 +1002,7 @@ class ApiMain extends ApiBase {
 	 */
 	protected function checkMaxLag( $module, $params ) {
 		if ( $module->shouldCheckMaxlag() && isset( $params['maxlag'] ) ) {
+			// Check for maxlag
 			$maxLag = $params['maxlag'];
 			list( $host, $lag ) = wfGetLB()->getMaxLag();
 			if ( $lag > $maxLag ) {
@@ -1147,7 +1148,6 @@ class ApiMain extends ApiBase {
 		) {
 			$this->dieUsageMsg( 'readrequired' );
 		}
-
 		if ( $module->isWriteMode() ) {
 			if ( !$this->mEnableWrite ) {
 				$this->dieUsageMsg( 'writedisabled' );
@@ -1155,7 +1155,9 @@ class ApiMain extends ApiBase {
 			if ( !$user->isAllowed( 'writeapi' ) ) {
 				$this->dieUsageMsg( 'writerequired' );
 			}
-			$this->checkReadOnly( $module );
+			if ( wfReadOnly() ) {
+				$this->dieReadOnly();
+			}
 		}
 
 		// Allow extensions to stop execution for arbitrary reasons.
@@ -1165,39 +1167,6 @@ class ApiMain extends ApiBase {
 		}
 	}
 
-	/**
-	 * Check if the DB is read-only for this user
-	 * @param ApiBase $module An Api module
-	 */
-	protected function checkReadOnly( $module ) {
-		if ( wfReadOnly() ) {
-			$this->dieReadOnly();
-		}
-
-		if ( $module->isWriteMode() && $this->getUser()->isAllowed( 'bot' ) ) {
-			// Figure out how many servers have passed the lag threshold
-			$numLagged = 0;
-			$lagLimit = $this->getConfig()->get( 'APIMaxLagThreshold' );
-			foreach ( wfGetLB()->getLagTimes() as $lag ) {
-				if ( $lag > $lagLimit ) {
-					++$numLagged;
-				}
-			}
-			// If a majority of slaves are too lagged then disallow writes
-			$slaveCount = wfGetLB()->getServerCount() - 1;
-			if ( $numLagged >= ceil( $slaveCount / 2 ) ) {
-				$parsed = $this->parseMsg( array( 'readonlytext' ) );
-				$this->dieUsage(
-					$parsed['info'],
-					$parsed['code'],
-					/* http error */
-					0,
-					array( 'readonlyreason' => "Waiting for $numLagged lagged database(s)" )
-				);
-			}
-		}
-	}
-
 	/**
 	 * Check asserts of the user's rights
 	 * @param array $params
diff --git a/includes/db/loadbalancer/LoadBalancer.php b/includes/db/loadbalancer/LoadBalancer.php
index a5a5c37d2b..bc9465ba60 100644
--- a/includes/db/loadbalancer/LoadBalancer.php
+++ b/includes/db/loadbalancer/LoadBalancer.php
@@ -68,9 +68,7 @@ class LoadBalancer {
 	/** @var integer Warn when this many connection are held */
 	const CONN_HELD_WARN_THRESHOLD = 10;
 	/** @var integer Default 'max lag' when unspecified */
-	const MAX_LAG = 10;
-	/** @var integer Max time to wait for a slave to catch up (e.g. ChronologyProtector) */
-	const POS_WAIT_TIMEOUT = 10;
+	const MAX_LAG = 30;
 
 	/**
 	 * @param array $params Array with keys:
@@ -84,7 +82,7 @@ class LoadBalancer {
 			throw new MWException( __CLASS__ . ': missing servers parameter' );
 		}
 		$this->mServers = $params['servers'];
-		$this->mWaitTimeout = self::POS_WAIT_TIMEOUT;
+		$this->mWaitTimeout = 10;
 
 		$this->mReadIndex = -1;
 		$this->mWriteIndex = -1;