resourceloader: Move packaging to a new getModuleContent() method

Centralise the building of module packages into this method so
that it can be easily re-used.

This is in preparation for providing the option for modules to use
content-based hashing (instead of based on meta-data) in the version
string of modules. Having a getModuleContent method allows that to
be implemented in a way that is well-cached (as we'll be calling it
from multiple multiple code paths) and without duplicating this logic.

Bug: T98087
Change-Id: I376233caaabe44b6101565b70a50904abdf8ab4f

includes/resourceloader/ResourceLoader.php

@@ -298,8 +298,16 @@ class ResourceLoader implements LoggerAwareInterface {
 	}
 
 	/**
-	 * @param MessageBlobStore $blobStore
+	 * @since 1.26
+	 * @return MessageBlobStore
+	 */
+	public function getMessageBlobStore() {
+		return $this->blobStore;
+	}
+
+	/**
 	 * @since 1.25
+	 * @param MessageBlobStore $blobStore
 	 */
 	public function setMessageBlobStore( MessageBlobStore $blobStore ) {
 		$this->blobStore = $blobStore;
@@ -962,7 +970,7 @@ MESSAGE;
 		// Pre-fetch blobs
 		if ( $context->shouldIncludeMessages() ) {
 			try {
-				$blobs = $this->blobStore->get( $this, $modules, $context->getLanguage() );
+				$this->blobStore->get( $this, $modules, $context->getLanguage() );
 			} catch ( Exception $e ) {
 				MWExceptionHandler::logException( $e );
 				$this->logger->warning( 'Prefetching MessageBlobStore failed: {exception}', array(
@@ -970,8 +978,6 @@ MESSAGE;
 				) );
 				$this->errors[] = self::formatExceptionNoComment( $e );
 			}
-		} else {
-			$blobs = array();
 		}
 
 		foreach ( $missing as $name ) {
@@ -981,79 +987,13 @@ MESSAGE;
 		// Generate output
 		$isRaw = false;
 		foreach ( $modules as $name => $module ) {
-			/**
-			 * @var $module ResourceLoaderModule
-			 */
-
 			try {
-				$scripts = '';
+				$content = $module->getModuleContent( $context );
-				if ( $context->shouldIncludeScripts() ) {
-					// If we are in debug mode, we'll want to return an array of URLs if possible
-					// However, we can't do this if the module doesn't support it
-					// We also can't do this if there is an only= parameter, because we have to give
-					// the module a way to return a load.php URL without causing an infinite loop
-					if ( $context->getDebug() && !$context->getOnly() && $module->supportsURLLoading() ) {
-						$scripts = $module->getScriptURLsForDebug( $context );
-					} else {
-						$scripts = $module->getScript( $context );
-						// rtrim() because there are usually a few line breaks
-						// after the last ';'. A new line at EOF, a new line
-						// added by ResourceLoaderFileModule::readScriptFiles, etc.
-						if ( is_string( $scripts )
-							&& strlen( $scripts )
-							&& substr( rtrim( $scripts ), -1 ) !== ';'
-						) {
-							// Append semicolon to prevent weird bugs caused by files not
-							// terminating their statements right (bug 27054)
-							$scripts .= ";\n";
-						}
-					}
-				}
-				// Styles
-				$styles = array();
-				if ( $context->shouldIncludeStyles() ) {
-					// Don't create empty stylesheets like array( '' => '' ) for modules
-					// that don't *have* any stylesheets (bug 38024).
-					$stylePairs = $module->getStyles( $context );
-					if ( count( $stylePairs ) ) {
-						// If we are in debug mode without &only= set, we'll want to return an array of URLs
-						// See comment near shouldIncludeScripts() for more details
-						if ( $context->getDebug() && !$context->getOnly() && $module->supportsURLLoading() ) {
-							$styles = array(
-								'url' => $module->getStyleURLsForDebug( $context )
-							);
-						} else {
-							// Minify CSS before embedding in mw.loader.implement call
-							// (unless in debug mode)
-							if ( !$context->getDebug() ) {
-								foreach ( $stylePairs as $media => $style ) {
-									// Can be either a string or an array of strings.
-									if ( is_array( $style ) ) {
-										$stylePairs[$media] = array();
-										foreach ( $style as $cssText ) {
-											if ( is_string( $cssText ) ) {
-												$stylePairs[$media][] = $this->filter( 'minify-css', $cssText );
-											}
-										}
-									} elseif ( is_string( $style ) ) {
-										$stylePairs[$media] = $this->filter( 'minify-css', $style );
-									}
-								}
-							}
-							// Wrap styles into @media groups as needed and flatten into a numerical array
-							$styles = array(
-								'css' => self::makeCombinedStyles( $stylePairs )
-							);
-						}
-					}
-				}
-
-				// Messages
-				$messagesBlob = isset( $blobs[$name] ) ? $blobs[$name] : '{}';
 
 				// Append output
 				switch ( $context->getOnly() ) {
 					case 'scripts':
+						$scripts = $content['scripts'];
 						if ( is_string( $scripts ) ) {
 							// Load scripts raw...
 							$out .= $scripts;
@@ -1063,6 +1003,7 @@ MESSAGE;
 						}
 						break;
 					case 'styles':
+						$styles = $content['styles'];
 						// We no longer seperate into media, they are all combined now with
 						// custom media type groups into @media .. {} sections as part of the css string.
 						// Module returns either an empty array or a numerical array with css strings.
@@ -1071,10 +1012,10 @@ MESSAGE;
 					default:
 						$out .= self::makeLoaderImplementScript(
 							$name,
-							$scripts,
+							isset( $content['scripts'] ) ? $content['scripts'] : '',
-							$styles,
+							isset( $content['styles'] ) ? $content['styles'] : array(),
-							new XmlJsCode( $messagesBlob ),
+							isset( $content['messagesBlob'] ) ? new XmlJsCode( $content['messagesBlob'] ) : array(),
-							$module->getTemplates()
+							isset( $content['templates'] ) ? $content['templates'] : array()
 						);
 						break;
 				}

includes/resourceloader/ResourceLoaderModule.php

@@ -64,6 +64,8 @@ abstract class ResourceLoaderModule {
 	protected $msgBlobMtime = array();
 	// In-object cache for version hash
 	protected $versionHash = array();
+	// In-object cache for module content
+	protected $contents = array();
 
 	// Whether the position returned by getPosition() is defined in the module configuration
 	// and not a default value
@@ -439,6 +441,122 @@ abstract class ResourceLoaderModule {
 		$this->msgBlobMtime[$lang] = $mtime;
 	}
 
+	/**
+	 * Get an array of this module's resources. Ready for serving to the web.
+	 *
+	 * @since 1.26
+	 * @param ResourceLoaderContext $context
+	 * @return array
+	 */
+	public function getModuleContent( ResourceLoaderContext $context ) {
+		$contextHash = $context->getHash();
+		// Cache this expensive operation. This calls builds the scripts, styles, and messages
+		// content which typically involves filesystem and/or database access.
+		if ( !array_key_exists( $contextHash, $this->contents ) ) {
+			$this->contents[ $contextHash ] = $this->buildContent( $context );
+		}
+		return $this->contents[ $contextHash ];
+	}
+
+	/**
+	 * Bundle all resources attached to this module into an array.
+	 *
+	 * @since 1.26
+	 * @param ResourceLoaderContext $context
+	 * @return array
+	 */
+	final protected function buildContent( ResourceLoaderContext $context ) {
+		$rl = $context->getResourceLoader();
+
+		// Only include properties that are relevant to this context (e.g. only=scripts)
+		// and that are non-empty (e.g. don't include "templates" for modules without
+		// templates). This helps prevent invalidating cache for all modules when new
+		// optional properties are introduced.
+		$content = array();
+
+		// Scripts
+		if ( $context->shouldIncludeScripts() ) {
+			// If we are in debug mode, we'll want to return an array of URLs if possible
+			// However, we can't do this if the module doesn't support it
+			// We also can't do this if there is an only= parameter, because we have to give
+			// the module a way to return a load.php URL without causing an infinite loop
+			if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
+				$scripts = $this->getScriptURLsForDebug( $context );
+			} else {
+				$scripts = $this->getScript( $context );
+				// rtrim() because there are usually a few line breaks
+				// after the last ';'. A new line at EOF, a new line
+				// added by ResourceLoaderFileModule::readScriptFiles, etc.
+				if ( is_string( $scripts )
+					&& strlen( $scripts )
+					&& substr( rtrim( $scripts ), -1 ) !== ';'
+				) {
+					// Append semicolon to prevent weird bugs caused by files not
+					// terminating their statements right (bug 27054)
+					$scripts .= ";\n";
+				}
+			}
+			$content['scripts'] = $scripts;
+		}
+
+		// Styles
+		if ( $context->shouldIncludeStyles() ) {
+			$styles = array();
+			// Don't create empty stylesheets like array( '' => '' ) for modules
+			// that don't *have* any stylesheets (bug 38024).
+			$stylePairs = $this->getStyles( $context );
+			if ( count( $stylePairs ) ) {
+				// If we are in debug mode without &only= set, we'll want to return an array of URLs
+				// See comment near shouldIncludeScripts() for more details
+				if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
+					$styles = array(
+						'url' => $this->getStyleURLsForDebug( $context )
+					);
+				} else {
+					// Minify CSS before embedding in mw.loader.implement call
+					// (unless in debug mode)
+					if ( !$context->getDebug() ) {
+						foreach ( $stylePairs as $media => $style ) {
+							// Can be either a string or an array of strings.
+							if ( is_array( $style ) ) {
+								$stylePairs[$media] = array();
+								foreach ( $style as $cssText ) {
+									if ( is_string( $cssText ) ) {
+										$stylePairs[$media][] = $rl->filter( 'minify-css', $cssText );
+									}
+								}
+							} elseif ( is_string( $style ) ) {
+								$stylePairs[$media] = $rl->filter( 'minify-css', $style );
+							}
+						}
+					}
+					// Wrap styles into @media groups as needed and flatten into a numerical array
+					$styles = array(
+						'css' => $rl->makeCombinedStyles( $stylePairs )
+					);
+				}
+			}
+			$content['styles'] = $styles;
+		}
+
+		// Messages
+		$blobs = $rl->getMessageBlobStore()->get(
+			$rl,
+			array( $this->getName() => $this ),
+			$context->getLanguage()
+		);
+		if ( isset( $blobs[$this->getName()] ) ) {
+			$content['messagesBlob'] = $blobs[$this->getName()];
+		}
+
+		$templates = $this->getTemplates();
+		if ( $templates ) {
+			$content['templates'] = $templates;
+		}
+
+		return $content;
+	}
+
 	/**
 	 * Get a string identifying the current version of this module in a given context.
 	 *