jenkins-bot has submitted this change and it was merged. (
https://gerrit.wikimedia.org/r/344058 )
Change subject: Add EtcdConfig class
......................................................................
Add EtcdConfig class
Bug: T156924
Change-Id: I60914d31c21484bfb935fe3d8c3168b51a2d5d1b
---
M autoload.php
A includes/config/EtcdConfig.php
M includes/libs/DnsSrvDiscoverer.php
M tests/phpunit/includes/libs/DnsSrvDiscovererTest.php
4 files changed, 344 insertions(+), 0 deletions(-)
Approvals:
Tim Starling: Looks good to me, approved
jenkins-bot: Verified
diff --git a/autoload.php b/autoload.php
index 3816485..f79c47e 100644
--- a/autoload.php
+++ b/autoload.php
@@ -427,6 +427,7 @@
'EnqueueableDataUpdate' => __DIR__ .
'/includes/deferred/EnqueueableDataUpdate.php',
'EraseArchivedFile' => __DIR__ . '/maintenance/eraseArchivedFile.php',
'ErrorPageError' => __DIR__ . '/includes/exception/ErrorPageError.php',
+ 'EtcdConfig' => __DIR__ . '/includes/config/EtcdConfig.php',
'EventRelayer' => __DIR__ .
'/includes/libs/eventrelayer/EventRelayer.php',
'EventRelayerGroup' => __DIR__ . '/includes/EventRelayerGroup.php',
'EventRelayerKafka' => __DIR__ .
'/includes/libs/eventrelayer/EventRelayerKafka.php',
diff --git a/includes/config/EtcdConfig.php b/includes/config/EtcdConfig.php
new file mode 100644
index 0000000..0f2f641
--- /dev/null
+++ b/includes/config/EtcdConfig.php
@@ -0,0 +1,275 @@
+<?php
+/**
+ * Copyright 2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @author Aaron Schulz
+ */
+
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
+use Wikimedia\WaitConditionLoop;
+
+/**
+ * Interface for configuration instances
+ *
+ * @since 1.29
+ */
+class EtcdConfig implements Config, LoggerAwareInterface {
+ /** @var MultiHttpClient */
+ private $http;
+ /** @var BagOStuff */
+ private $srvCache;
+ /** @var array */
+ private $procCache;
+ /** @var LoggerInterface */
+ private $logger;
+
+ /** @var string */
+ private $host;
+ /** @var string */
+ private $protocol;
+ /** @var string */
+ private $directory;
+ /** @var string */
+ private $encoding;
+ /** @var integer */
+ private $baseCacheTTL;
+ /** @var integer */
+ private $skewCacheTTL;
+ /** @var integer */
+ private $timeout;
+ /** @var string */
+ private $directoryHash;
+
+ /**
+ * @param array $params Parameter map:
+ * - host: the host address and port
+ * - protocol: either http or https
+ * - directory: the etc "directory" were MediaWiki specific variables
are located
+ * - encoding: one of ("JSON", "YAML")
+ * - cache: BagOStuff instance or ObjectFactory spec thereof for a
server cache.
+ * The cache will also be used as a fallback if etcd is down.
+ * - cacheTTL: logical cache TTL in seconds
+ * - skewTTL: maximum seconds to randomly lower the assigned TTL on
cache save
+ * - timeout: seconds to wait for etcd before throwing an error
+ */
+ public function __construct( array $params ) {
+ $params += [
+ 'protocol' => 'http',
+ 'encoding' => 'JSON',
+ 'cacheTTL' => 10,
+ 'skewTTL' => 1,
+ 'timeout' => 10
+ ];
+
+ $this->host = $params['host'];
+ $this->protocol = $params['protocol'];
+ $this->directory = trim( $params['directory'], '/' );
+ $this->directoryHash = sha1( $this->directory );
+ $this->encoding = $params['encoding'];
+ $this->skewCacheTTL = $params['skewTTL'];
+ $this->baseCacheTTL = max( $params['cacheTTL'] -
$this->skewCacheTTL, 0 );
+ $this->timeout = $params['timeout'];
+
+ if ( !isset( $params['cache'] ) ) {
+ $this->srvCache = new HashBagOStuff( [] );
+ } elseif ( $params['cache'] instanceof BagOStuff ) {
+ $this->srvCache = $params['cache'];
+ } else {
+ $this->srvCache = ObjectFactory::getObjectFromSpec(
$params['cache'] );
+ }
+
+ $this->logger = new Psr\Log\NullLogger();
+ $this->http = new MultiHttpClient( [
+ 'connTimeout' => $this->timeout,
+ 'reqTimeout' => $this->timeout
+ ] );
+ }
+
+ public function setLogger( LoggerInterface $logger ) {
+ $this->logger = $logger;
+ }
+
+ public function has( $name ) {
+ $this->load();
+
+ return array_key_exists( $name, $this->procCache['config'] );
+ }
+
+ public function get( $name ) {
+ $this->load();
+
+ if ( !array_key_exists( $name, $this->procCache['config'] ) ) {
+ throw new ConfigException( "No entry found for
'$name'." );
+ }
+
+ return $this->procCache['config'][$name];
+ }
+
+ private function load() {
+ if ( $this->procCache !== null ) {
+ return; // already loaded
+ }
+
+ $now = microtime( true );
+ $key = $this->srvCache->makeKey( 'variable',
$this->directoryHash );
+
+ // Get the cached value or block until it is regenerated (by
this or another thread)...
+ $data = null; // latest config info
+ $error = null; // last error message
+ $loop = new WaitConditionLoop(
+ function () use ( $key, $now, &$data, &$error ) {
+ // Check if the values are in cache yet...
+ $data = $this->srvCache->get( $key );
+ if ( is_array( $data ) && $data['expires'] >
$now ) {
+ $this->logger->debug( "Found up-to-date
etcd configuration cache." );
+
+ return
WaitConditionLoop::CONDITION_REACHED;
+ }
+
+ // Cache is either empty or stale;
+ // refresh the cache from etcd, using a mutex
to reduce stampedes...
+ if ( $this->srvCache->lock( $key, 0,
$this->baseCacheTTL ) ) {
+ try {
+ list( $config, $error, $retry )
= $this->fetchAllFromEtcd();
+ if ( $config === null ) {
+ $this->logger->error(
"Failed to fetch configuration: $error" );
+ // Fail fast if the
error is likely to just keep happening
+ return $retry
+ ?
WaitConditionLoop::CONDITION_CONTINUE
+ :
WaitConditionLoop::CONDITION_FAILED;
+ }
+
+ // Avoid having all servers
expire cache keys at the same time
+ $expiry = microtime( true ) +
$this->baseCacheTTL;
+ $expiry += mt_rand( 0, 1e6 ) /
1e6 * $this->skewCacheTTL;
+
+ $data = [ 'config' => $config,
'expires' => $expiry ];
+ $this->srvCache->set( $key,
$data, BagOStuff::TTL_INDEFINITE );
+
+ $this->logger->info( "Refreshed
stale etcd configuration cache." );
+
+ return
WaitConditionLoop::CONDITION_REACHED;
+ } finally {
+ $this->srvCache->unlock( $key
); // release mutex
+ }
+ }
+
+ if ( is_array( $data ) ) {
+ $this->logger->info( "Using stale etcd
configuration cache." );
+
+ return
WaitConditionLoop::CONDITION_REACHED;
+ }
+
+ return WaitConditionLoop::CONDITION_CONTINUE;
+ },
+ $this->timeout
+ );
+
+ if ( $loop->invoke() !== WaitConditionLoop::CONDITION_REACHED )
{
+ // No cached value exists and etcd query failed; throw
an error
+ throw new ConfigException( "Failed to load
configuration from etcd: $error" );
+ }
+
+ $this->procCache = $data;
+ }
+
+ /**
+ * @return array (config array or null, error string, allow retries)
+ */
+ public function fetchAllFromEtcd() {
+ $dsd = new DnsSrvDiscoverer( $this->host );
+ $servers = $dsd->getServers();
+ if ( !$servers ) {
+ return $this->fetchAllFromEtcdServer( $this->host );
+ }
+
+ do {
+ // Pick a random etcd server from dns
+ $server = $dsd->pickServer( $servers );
+ $host = IP::combineHostAndPort( $server['target'],
$server['port'] );
+ // Try to load the config from this particular server
+ list( $config, $error, $retry ) =
$this->fetchAllFromEtcdServer( $host );
+ if ( is_array( $config ) || !$retry ) {
+ break;
+ }
+
+ // Avoid the server next time if that failed
+ $dsd->removeServer( $server, $servers );
+ } while ( $servers );
+
+ return [ $config, $error, $retry ];
+ }
+
+ /**
+ * @param string $address Host and port
+ * @return array (config array or null, error string, whether to allow
retries)
+ */
+ protected function fetchAllFromEtcdServer( $address ) {
+ // Retrieve all the values under the MediaWiki config directory
+ list( $rcode, $rdesc, /* $rhdrs */, $rbody, $rerr ) =
$this->http->run( [
+ 'method' => 'GET',
+ 'url' =>
"{$this->protocol}://{$address}/v2/keys/{$this->directory}/",
+ 'headers' => [ 'content-type' => 'application/json' ]
+ ] );
+
+ static $terminalCodes = [ 404 => true ];
+ if ( $rcode < 200 || $rcode > 399 ) {
+ return [
+ null,
+ strlen( $rerr ) ? $rerr : "HTTP $rcode
($rdesc)",
+ empty( $terminalCodes[$rcode] )
+ ];
+ }
+
+ $info = json_decode( $rbody, true );
+ if ( $info === null || !isset( $info['node']['nodes'] ) ) {
+ return [ null, $rcode, "Unexpected JSON response;
missing 'nodes' list.", false ];
+ }
+
+ $config = [];
+ foreach ( $info['node']['nodes'] as $node ) {
+ if ( !empty( $node['dir'] ) ) {
+ continue; // skip directories
+ }
+
+ $name = basename( $node['key'] );
+ $value = $this->unserialize( $node['value'] );
+ if ( !is_array( $value ) || !isset( $value['val'] ) ) {
+ return [ null, "Failed to parse value for
'$name'.", false ];
+ }
+
+ $config[$name] = $value['val'];
+ }
+
+ return [ $config, null, false ];
+ }
+
+ /**
+ * @param string $string
+ * @return mixed
+ */
+ private function unserialize( $string ) {
+ if ( $this->encoding === 'YAML' ) {
+ return yaml_parse( $string );
+ } else { // JSON
+ return json_decode( $string, true );
+ }
+ }
+}
diff --git a/includes/libs/DnsSrvDiscoverer.php
b/includes/libs/DnsSrvDiscoverer.php
index c33264d..ce8a204 100644
--- a/includes/libs/DnsSrvDiscoverer.php
+++ b/includes/libs/DnsSrvDiscoverer.php
@@ -84,6 +84,22 @@
}
/**
+ * @param array $server
+ * @param array $servers
+ * @return array[]
+ */
+ public function removeServer( $server, array $servers ) {
+ foreach ( $servers as $i => $srv ) {
+ if ( $srv['target'] === $server['target'] &&
$srv['port'] === $server['port'] ) {
+ unset( $servers[$i] );
+ break;
+ }
+ }
+
+ return array_values( $servers );
+ }
+
+ /**
* @return array[]
*/
protected function getDnsRecords() {
diff --git a/tests/phpunit/includes/libs/DnsSrvDiscovererTest.php
b/tests/phpunit/includes/libs/DnsSrvDiscovererTest.php
index f768d06..cfd4d76 100644
--- a/tests/phpunit/includes/libs/DnsSrvDiscovererTest.php
+++ b/tests/phpunit/includes/libs/DnsSrvDiscovererTest.php
@@ -85,4 +85,56 @@
],
];
}
+
+ public function testRemoveServer() {
+ $dsd = new DnsSrvDiscoverer( 'localhost' );
+
+ $servers = [
+ [
+ 'target' => 'conf1001.eqiad.wmnet',
+ 'port' => 35,
+ 'pri' => 2,
+ 'weight' => 1,
+ ],
+ [
+ 'target' => 'conf1004.eqiad.wmnet',
+ 'port' => 74,
+ 'pri' => 2,
+ 'weight' => 1,
+ ],
+ [
+ 'target' => 'conf1005.eqiad.wmnet',
+ 'port' => 77,
+ 'pri' => 3,
+ 'weight' => 1,
+ ],
+ ];
+ $server = $servers[1];
+
+ $expected = [
+ [
+ 'target' => 'conf1001.eqiad.wmnet',
+ 'port' => 35,
+ 'pri' => 2,
+ 'weight' => 1,
+ ],
+ [
+ 'target' => 'conf1005.eqiad.wmnet',
+ 'port' => 77,
+ 'pri' => 3,
+ 'weight' => 1,
+ ],
+ ];
+
+ $this->assertEquals(
+ $expected,
+ $dsd->removeServer( $server, $servers ),
+ "Correct server removed"
+ );
+ $this->assertEquals(
+ $expected,
+ $dsd->removeServer( $server, $servers ),
+ "Nothing to remove"
+ );
+ }
}
--
To view, visit https://gerrit.wikimedia.org/r/344058
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: merged
Gerrit-Change-Id: I60914d31c21484bfb935fe3d8c3168b51a2d5d1b
Gerrit-PatchSet: 12
Gerrit-Project: mediawiki/core
Gerrit-Branch: master
Gerrit-Owner: Aaron Schulz <[email protected]>
Gerrit-Reviewer: Aaron Schulz <[email protected]>
Gerrit-Reviewer: Giuseppe Lavagetto <[email protected]>
Gerrit-Reviewer: Krinkle <[email protected]>
Gerrit-Reviewer: Legoktm <[email protected]>
Gerrit-Reviewer: Tim Starling <[email protected]>
Gerrit-Reviewer: Volans <[email protected]>
Gerrit-Reviewer: jenkins-bot <>
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