MediaWiki master
ExternalStoreAccess.php
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1<?php
21use Psr\Log\LoggerAwareInterface;
22use Psr\Log\LoggerInterface;
23use Psr\Log\NullLogger;
24use Wikimedia\RequestTimeout\TimeoutException;
25
43class ExternalStoreAccess implements LoggerAwareInterface {
45 private $storeFactory;
47 private $logger;
48
53 public function __construct( ExternalStoreFactory $factory, LoggerInterface $logger = null ) {
54 $this->storeFactory = $factory;
55 $this->logger = $logger ?: new NullLogger();
56 }
57
58 public function setLogger( LoggerInterface $logger ) {
59 $this->logger = $logger;
60 }
61
72 public function fetchFromURL( $url, array $params = [] ) {
73 return $this->storeFactory->getStoreForUrl( $url, $params )->fetchFromURL( $url );
74 }
75
86 public function fetchFromURLs( array $urls, array $params = [] ) {
87 $batches = $this->storeFactory->getUrlsByProtocol( $urls );
88 $retval = [];
89 foreach ( $batches as $proto => $batchedUrls ) {
90 $store = $this->storeFactory->getStore( $proto, $params );
91 $retval += $store->batchFetchFromURLs( $batchedUrls );
92 }
93 // invalid, not found, db dead, etc.
94 $missing = array_diff( $urls, array_keys( $retval ) );
95 foreach ( $missing as $url ) {
96 $retval[$url] = false;
97 }
98
99 return $retval;
100 }
101
117 public function insert( $data, array $params = [], array $tryStores = null ) {
118 $tryStores ??= $this->storeFactory->getWriteBaseUrls();
119 if ( !$tryStores ) {
120 throw new ExternalStoreException( "List of external stores provided is empty." );
121 }
122
123 $error = false; // track the last exception thrown
124 $readOnlyCount = 0; // track if a store was read-only
125 while ( count( $tryStores ) > 0 ) {
126 $index = mt_rand( 0, count( $tryStores ) - 1 );
127 $storeUrl = $tryStores[$index];
128
129 $this->logger->debug( __METHOD__ . ": trying $storeUrl" );
130
131 $store = $this->storeFactory->getStoreForUrl( $storeUrl, $params );
132 if ( $store === false ) {
133 throw new ExternalStoreException( "Invalid external storage protocol - $storeUrl" );
134 }
135
136 $location = $this->storeFactory->getStoreLocationFromUrl( $storeUrl );
137 try {
138 if ( $store->isReadOnly( $location ) ) {
139 $readOnlyCount++;
140 $msg = 'read only';
141 } else {
142 $url = $store->store( $location, $data );
143 if ( strlen( $url ) ) {
144 // A store accepted the write; done!
145 return $url;
146 }
147 throw new ExternalStoreException(
148 "No URL returned by storage medium ($storeUrl)"
149 );
150 }
151 } catch ( TimeoutException $e ) {
152 throw $e;
153 } catch ( Exception $ex ) {
154 $error = $ex;
155 $msg = 'caught ' . get_class( $error ) . ' exception: ' . $error->getMessage();
156 }
157
158 unset( $tryStores[$index] ); // Don't try this one again!
159 $tryStores = array_values( $tryStores ); // Must have consecutive keys
160 $this->logger->error(
161 "Unable to store text to external storage {store_path} ({failure})",
162 [ 'store_path' => $storeUrl, 'failure' => $msg ]
163 );
164 }
165
166 // We only get here when all stores failed.
167 if ( $error ) {
168 // At least one store threw an exception. Re-throw the most recent one.
169 throw $error;
170 } elseif ( $readOnlyCount ) {
171 // If no exceptions where thrown and we get here,
172 // this should mean that all stores were in read-only mode.
173 throw new ReadOnlyError();
174 } else {
175 // We shouldn't get here. If there were no failures, this method should have returned
176 // from inside the body of the loop.
177 throw new LogicException( "Unexpected failure to store text to external store" );
178 }
179 }
180
186 public function isReadOnly( $storeUrls = null ) {
187 if ( $storeUrls === null ) {
188 $storeUrls = $this->storeFactory->getWriteBaseUrls();
189 } else {
190 $storeUrls = is_array( $storeUrls ) ? $storeUrls : [ $storeUrls ];
191 }
192
193 if ( !$storeUrls ) {
194 return false; // no stores exists which can be "read only"
195 }
196
197 foreach ( $storeUrls as $storeUrl ) {
198 $store = $this->storeFactory->getStoreForUrl( $storeUrl );
199 $location = $this->storeFactory->getStoreLocationFromUrl( $storeUrl );
200 if ( $store !== false && !$store->isReadOnly( $location ) ) {
201 return false; // at least one store is not read-only
202 }
203 }
204
205 return true; // all stores are read-only
206 }
207}
This is the main interface for fetching or inserting objects with ExternalStore.
insert( $data, array $params=[], array $tryStores=null)
Insert data into storage and return the assigned URL.
setLogger(LoggerInterface $logger)
fetchFromURL( $url, array $params=[])
Fetch data from given URL.
fetchFromURLs(array $urls, array $params=[])
Fetch data from multiple URLs with a minimum of round trips.
isReadOnly( $storeUrls=null)
__construct(ExternalStoreFactory $factory, LoggerInterface $logger=null)
Show an error when the wiki is locked/read-only and the user tries to do something that requires writ...