Duplicate Queries, Slowness

Hi there,

I’m using this plugin on a website, however I’ve noticed that the plugin created a few performance issues for us.

I have modified the plugin slightly, just thought that you might be interested in the changes.

The changes have been made to the resolve_image_id function in /wp-content/plugins/gallery-custom-links/mgcl_core.php

Original:

	function resolve_image_id( $url ) {
		global $wpdb;
		$pattern = '/[_-]\d+x\d+(?=\.[a-z]{3,4}$)/';
		$url = preg_replace( $pattern, '', $url );
		$url = $this->get_pathinfo_from_image_src( $url );
		$urlLike = '%' . $url . '%';
		$query = $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE guid LIKE '%s'", $urlLike );
		$attachment = $wpdb->get_col( $query );

		// Code proposed by @wizardcoder
		// https://www.ads-software.com/support/topic/issue-with-page-links-on-images/
		if ( empty( $attachment ) ) {
			$query = $wpdb->prepare( 
				"SELECT post_id FROM $wpdb->postmeta WHERE meta_value LIKE '%s' AND meta_key = '_wp_attached_file'", 
				$urlLike 
			);
			$attachment = $wpdb->get_col( $query );
		}

		return empty( $attachment ) ? null : $attachment[0];
	}

Modified:
I added ” Limit 1 ” to the SQL queries to make them stop searching if they find a result.
I also added a “cache” array to stop multiple SQL queries from being executed for the same url on a single page load.

function resolve_image_id( $url ) {
		global $wpdb;
		global $galleryCustomLinksCache;
		
		if(!is_array($galleryCustomLinksCache)){
		    $galleryCustomLinksCache = [];
		}
		
		$pattern = '/[_-]\d+x\d+(?=\.[a-z]{3,4}$)/';
		$url = preg_replace( $pattern, '', $url );
		$url = $this->get_pathinfo_from_image_src( $url );
		$urlLike = '%' . $url . '%';
		
		if(array_key_exists($urlLike, $galleryCustomLinksCache)){
		    $attachment = $galleryCustomLinksCache[$urlLike];   
		}else{
    		$query = $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE guid LIKE '%s' LIMIT 1", $urlLike );
    		$attachment = $wpdb->get_col( $query );
    
    		// Code proposed by @wizardcoder
    		// https://www.ads-software.com/support/topic/issue-with-page-links-on-images/
    		if ( empty( $attachment ) ) {
    			$query = $wpdb->prepare( 
    				"SELECT post_id FROM $wpdb->postmeta WHERE meta_value LIKE '%s' AND meta_key = '_wp_attached_file' LIMIT 1", 
    				$urlLike 
    			);
    			$attachment = $wpdb->get_col( $query );
    		}
    		
    		$galleryCustomLinksCache[$urlLike] = $attachment;   
		}

		return empty( $attachment ) ? null : $attachment[0];
	}