Added backtraces to HTTP calls.

Fixes #16

src/Record/Http_Record_Collector.php

@@ -3,13 +3,21 @@ declare( strict_types=1 );
 
 namespace Rarst\Laps\Record;
 
+use Rarst\Laps\Formatter\Backtrace_Formatter;
 use Symfony\Component\Stopwatch\Stopwatch;
+use Symfony\Component\Stopwatch\StopwatchEvent;
 
 /**
  * Captures time of network requests made with HTTP API.
  */
 class Http_Record_Collector extends Stopwatch_Record_Collector {
 
+	/** @var Backtrace_Formatter */
+	private $formatter;
+
+	/** @var array */
+	private $callers = [];
+
 	/**
 	 * @param Stopwatch $stopwatch Stopwatch instance.
 	 */
@@ -17,6 +25,8 @@ class Http_Record_Collector extends Stopwatch_Record_Collector {
 
 		parent::__construct( $stopwatch );
 
+		$this->formatter = new Backtrace_Formatter();
+
 		add_action( 'pre_http_request', [ $this, 'pre_http_request' ], 10, 3 );
 		add_action( 'http_api_debug', [ $this, 'http_api_debug' ], 10, 5 );
 	}
@@ -33,6 +43,7 @@ class Http_Record_Collector extends Stopwatch_Record_Collector {
 	public function pre_http_request( bool $false, array $args, string $url ): bool {
 
 		$this->start( $url, 'http' );
+		$this->callers[ $url ] = wp_debug_backtrace_summary( __CLASS__, 5, true );
 
 		return $false;
 	}
@@ -56,4 +67,17 @@ class Http_Record_Collector extends Stopwatch_Record_Collector {
 
 		return $response;
 	}
+
+	/**
+	 * @param string         $name  Event name.
+	 * @param StopwatchEvent $event Stopwatch event instance.
+	 *
+	 * @return Stopwatch_Record
+	 */
+	public function transform( string $name, StopwatchEvent $event ): Stopwatch_Record {
+
+		$backtrace = $this->formatter->format( $this->callers[ $name ] );
+
+		return new Stopwatch_Record( $name, $event, implode( ' → ', $backtrace ) );
+	}
 }