From 44724baa9faaeb9ebfee2fd1211f42a30fb2fff6 Mon Sep 17 00:00:00 2001
From: Mike Crantea <mike.crantea@xwp.co>
Date: Mon, 30 Mar 2020 16:50:06 +0100
Subject: [PATCH] 0.3.3 - Add possibility to report events only on % of traffic

---
 README.md                    | 10 ++++++++++
 php/Plugin.php               | 25 ++++++++++++++++++++++---
 site-performance-tracker.php |  2 +-
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index ee6592c..30f5de1 100644
--- a/README.md
+++ b/README.md
@@ -76,6 +76,16 @@ if ( function_exists( 'get_the_performance_mark' ) ) {
 }
 ```
 
+### Limit the number of events sent
+
+Using the following filter you can send the events for a limited percentage of your traffic, this limits the performance metrics to be sent only for 5% of the traffic:
+
+```php
+add_filter( 'site_performance_tracker_chance', function() {
+	return 0.05;
+} );
+```
+
 ### Hooks
 
 There are the following hooks available to further customize the way the plugin works:
diff --git a/php/Plugin.php b/php/Plugin.php
index b39de73..a1d95cb 100644
--- a/php/Plugin.php
+++ b/php/Plugin.php
@@ -20,6 +20,13 @@ class Plugin {
 	 */
 	protected $default_entry_types = array( 'paint', 'navigation', 'mark', 'first-input' );
 
+	/**
+	 * PerformanceObserver default chance of sending performance metrics to analytics.
+	 *
+	 * @var array
+	 */
+	protected $default_chance = 1;
+
 	/**
 	 * Initialize the plugin.
 	 */
@@ -87,10 +94,18 @@ public function inject_performance_observer() {
 		 */
 		$entry_types = apply_filters( 'site_performance_tracker_entry_types', $this->default_entry_types );
 
+		/**
+		 * Limits the percentage of traffic chance of sending events to analytics.
+		 *
+		 * @param number $entry_chance Chance - a number between 0 and 1.
+		 */
+		$chance = apply_filters( 'site_performance_tracker_chance', $this->default_chance );
+
 		// Options object passed to JS.
 		$options = array(
 			'categoryName' => $category_name,
 			'entryTypes'   => $entry_types,
+			'chance'       => $chance,
 		);
 
 		?>
@@ -130,9 +145,13 @@ public function inject_performance_observer() {
 						}
 					}
 				} );
-				window.sitePerformanceObserver.instance.observe( {
-					entryTypes: window.sitePerformanceObserver.entryTypes
-				} );
+				var randNumber = Math.random();
+				if ( randNumber <= window.sitePerformanceObserver.chance ) {
+					window.sitePerformanceObserver.instance.observe( {
+						entryTypes: window.sitePerformanceObserver.entryTypes
+					} );
+				}
+
 			}
 		</script>
 		<?php
diff --git a/site-performance-tracker.php b/site-performance-tracker.php
index 4972f8d..6b46679 100644
--- a/site-performance-tracker.php
+++ b/site-performance-tracker.php
@@ -8,7 +8,7 @@
  * Plugin Name: Site Performance Tracker
  * Plugin URI: https://github.com/xwp/site-performance-tracker
  * Description: Allows you to detect and track site performance metrics.
- * Version: 0.3.2
+ * Version: 0.3.3
  * Author: XWP.co
  * Author URI: https://xwp.co
  */