oom-elementor-query-trace.php

<?php
/**
 * Plugin Name: OOM Elementor Query Trace
 * Description: On a memory fatal, log the SELECT wpdb was fetching and who ran it.
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

final class OOM_Query_Trace {
	const RESERVE_BYTES = 8388608;
	const MAX_QUERIES   = 12;

	private static $reserve = '';
	private static $queries = array();

	public static function boot() {
		if ( ! self::should_trace_request() ) {
			return;
		}

		self::$reserve = str_repeat( 'x', self::RESERVE_BYTES );
		add_filter( 'query', array( __CLASS__, 'capture' ), PHP_INT_MAX );
		register_shutdown_function( array( __CLASS__, 'shutdown' ) );
	}

	public static function capture( $query ) {
		$sql  = (string) $query;
		$item = array(
			'bytes'   => strlen( $sql ),
			'sql'     => self::clip( $sql, 800 ),
			'mem'     => memory_get_usage( true ),
			'callers' => array(),
		);

		self::$queries[] = $item;
		if ( count( self::$queries ) > self::MAX_QUERIES ) {
			array_shift( self::$queries );
		}

		$index = count( self::$queries ) - 1;
		self::$queries[ $index ]['callers'] = self::callers();

		return $query;
	}

	public static function shutdown() {
		self::$reserve = '';

		$err = error_get_last();
		if ( ! is_array( $err ) || empty( $err['message'] ) ) {
			return;
		}
		if ( false === stripos( $err['message'], 'Allowed memory size' ) ) {
			return;
		}

		global $wpdb;

		$lines   = array();
		$lines[] = '=== ' . gmdate( 'c' ) . ' memory exhausted ===';
		$lines[] = 'message: ' . $err['message'];
		$lines[] = 'file: ' . ( isset( $err['file'] ) ? $err['file'] : '' ) . ':' . ( isset( $err['line'] ) ? $err['line'] : '' );
		$lines[] = 'memory_limit: ' . ini_get( 'memory_limit' );
		$lines[] = 'peak: ' . self::bytes( memory_get_peak_usage( true ) );
		$lines[] = 'request: ' . ( isset( $_SERVER['REQUEST_METHOD'] ) ? $_SERVER['REQUEST_METHOD'] : '' ) . ' ' . self::clip( isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '', 500 );
		$lines[] = 'script: ' . ( isset( $_SERVER['SCRIPT_NAME'] ) ? $_SERVER['SCRIPT_NAME'] : '' );
		$lines[] = 'post_action: ' . self::scalar_request( 'action' );
		$lines[] = 'editor_post_id: ' . self::scalar_request( 'editor_post_id' );
		$lines[] = 'post_id: ' . self::scalar_request( 'post_id' );
		$lines[] = self::elementor_actions();

		if ( isset( $GLOBALS['wp_current_filter'] ) && is_array( $GLOBALS['wp_current_filter'] ) ) {
			$lines[] = 'current_filter: ' . implode( ' > ', $GLOBALS['wp_current_filter'] );
		}

		if ( isset( $wpdb ) && is_object( $wpdb ) ) {
			$last = isset( $wpdb->last_query ) ? (string) $wpdb->last_query : '';
			$fetched = ( isset( $wpdb->last_result ) && is_array( $wpdb->last_result ) ) ? count( $wpdb->last_result ) : 0;

			$lines[] = 'last_query_bytes: ' . strlen( $last );
			$lines[] = 'rows_fetched_before_crash: ' . $fetched;
			$lines[] = 'last_query: ' . self::clip( $last, 1500 );

			if ( isset( $wpdb->result ) && $wpdb->result instanceof mysqli_result ) {
				$lines[] = 'mysqli_num_rows: ' . mysqli_num_rows( $wpdb->result );
				$fields  = mysqli_fetch_fields( $wpdb->result );
				if ( is_array( $fields ) ) {
					$parts = array();
					foreach ( $fields as $field ) {
						$parts[] = $field->table . '.' . $field->name . ' max_bytes=' . $field->max_length;
					}
					$lines[] = 'columns: ' . implode( ' | ', $parts );
				}
			}

			if ( $fetched > 0 ) {
				$lines[] = 'first_row: ' . self::row_profile( $wpdb->last_result[0] );
				if ( $fetched > 1 ) {
					$lines[] = 'last_stored_row: ' . self::row_profile( $wpdb->last_result[ $fetched - 1 ] );
				}
			}
		}

		$lines[] = 'recent_queries:';
		$i = 1;
		foreach ( self::$queries as $query ) {
			$lines[] = $i . '. bytes=' . $query['bytes'] . ' mem=' . self::bytes( $query['mem'] );
			$lines[] = '   sql: ' . $query['sql'];
			foreach ( $query['callers'] as $caller ) {
				$lines[] = '   at ' . $caller;
			}
			$i++;
		}
		$lines[] = '';

		$report = implode( "\n", $lines );
		$dir    = defined( 'WP_CONTENT_DIR' ) ? WP_CONTENT_DIR : dirname( __DIR__ );
		file_put_contents( $dir . '/oom-query-trace.log', $report, FILE_APPEND | LOCK_EX );

		error_log( 'OOM trace written to wp-content/oom-query-trace.log; ' . self::clip( str_replace( "\n", ' | ', $report ), 1800 ) );
	}

	private static function should_trace_request() {
		$uri    = isset( $_SERVER['REQUEST_URI'] ) ? (string) $_SERVER['REQUEST_URI'] : '';
		$action = isset( $_REQUEST['action'] ) ? (string) $_REQUEST['action'] : '';

		if ( false !== strpos( $action, 'elementor' ) ) {
			return true;
		}

		foreach ( array( 'wp-admin', 'admin-ajax.php', 'wp-json', 'elementor' ) as $needle ) {
			if ( false !== strpos( $uri, $needle ) ) {
				return true;
			}
		}

		return false;
	}

	private static function callers() {
		$frames = debug_backtrace( DEBUG_BACKTRACE_IGNORE_ARGS, 12 );
		$skip   = array(
			'capture',
			'callers',
			'apply_filters',
			'apply_filters_ref_array',
			'query',
			'_do_query',
			'get_results',
			'get_row',
			'get_var',
			'get_col',
		);
		$out = array();

		foreach ( $frames as $frame ) {
			$fn = isset( $frame['function'] ) ? $frame['function'] : '';
			if ( in_array( $fn, $skip, true ) ) {
				continue;
			}

			$file = isset( $frame['file'] ) ? $frame['file'] : '';
			if ( defined( 'ABSPATH' ) && $file && 0 === strpos( $file, ABSPATH ) ) {
				$file = substr( $file, strlen( ABSPATH ) );
			}

			$class = isset( $frame['class'] ) ? $frame['class'] . $frame['type'] : '';
			$out[] = $file . ':' . ( isset( $frame['line'] ) ? $frame['line'] : '' ) . ' ' . $class . $fn;

			if ( count( $out ) >= 6 ) {
				break;
			}
		}

		return $out;
	}

	private static function elementor_actions() {
		if ( empty( $_POST['actions'] ) || ! is_string( $_POST['actions'] ) ) {
			return 'elementor_actions: (none)';
		}

		$raw = $_POST['actions'];
		preg_match_all( '/"action"\s*:\s*"([A-Za-z0-9_\\\\]+)"/', substr( $raw, 0, 80000 ), $matches );
		$names = array_slice( array_unique( $matches[1] ), 0, 20 );

		return 'elementor_actions_bytes: ' . strlen( $raw ) . ' names: ' . implode( ',', $names );
	}

	private static function row_profile( $row ) {
		if ( ! is_object( $row ) ) {
			return '';
		}

		$parts = array();
		$seen  = 0;
		foreach ( $row as $key => $value ) {
			if ( $seen >= 30 ) {
				$parts[] = '...';
				break;
			}
			$parts[] = $key . '=' . ( is_string( $value ) ? strlen( $value ) . 'b' : gettype( $value ) );
			$seen++;
		}

		return implode( ', ', $parts );
	}

	private static function scalar_request( $key ) {
		if ( ! isset( $_REQUEST[ $key ] ) || is_array( $_REQUEST[ $key ] ) ) {
			return '';
		}
		return self::clip( (string) $_REQUEST[ $key ], 80 );
	}

	private static function clip( $text, $limit ) {
		$text = (string) $text;
		if ( strlen( $text ) <= $limit ) {
			return $text;
		}
		return substr( $text, 0, $limit ) . '…[' . strlen( $text ) . ' bytes]';
	}

	private static function bytes( $bytes ) {
		return round( $bytes / 1048576, 1 ) . 'MB';
	}
}

OOM_Query_Trace::boot();