Add an option to control xhprof enable conditions

README.md

@@ -0,0 +1,54 @@
+To begin with, you need to install the XHProf extension. Refer to the [PHP documentation](http://www.php.net/manual/en/xhprof.setup.php) if you need assistance.
+
+You will need to manually create the database and populate it with the provided scheme. The database scheme is located at `/setup/database.sql`.
+
+Rename the `/xhprof/includes/config.inc.sample.php` to `/xhprof/includes/config.inc.php`. There are only two supported parameters.
+
+* `xhprof_url` is the URL to the XHProf.io library.
+* `pdo` is the PDO instance. This library uses [PDO](http://uk3.php.net/pdo) to handle all of the database operations.
+* `enable` is a closure to control when enable data collection, return true means always enable
+
+Some cases for reference:
+
+Alway enable
+``` php
+'enable' => function() {
+     return true;
+}
+```
+
+Enable if url contents `debug` parameter:
+``` php
+'enable' => function() {
+    if (!empty($_GET['debug'])) {
+        return true;
+    }
+}
+```
+
+Enable for 1/100 probability
+``` php
+'enable' => function() {
+    return rand(0, 100) === 42;
+}
+```
+
+Enable for url path is `/`:
+``` php
+'enable' => function() {
+    if (parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH) === '/') {
+        return true;
+    }
+}
+```
+
+
+For XHProf.io to start collecting data, you need `/inc/inject.php` files included to every file of interest. The recommended approach is to update your `php.ini` configuration to automatically prepend and append these files.
+
+    auto_prepend_file = /[absolute path to xhprof.io]/inc/inject.php
+
+If you use nginx, you could configuration `auto_prepend_file` as a `fastcgi_param`
+
+    fastcgi_param  PHP_VALUE "auto_prepend_file=/[absolute path to xhprof.io]/inc/inject.php";
+
+If you are using PHP-FPM, then XHProf.io will utilise `fastcgi_finish_request` to hide any overhead related to data collection. There is nothing to worry about if you are not using PHP-FPM either, as the overhead is less than a few milliseconds.

inc/inject.php

@@ -0,0 +1,16 @@
+<?php
+if (extension_loaded('xhprof')) {
+    $xhprof_config			= require __DIR__ . '/../xhprof/includes/config.inc.php';
+    if (!empty($xhprof_config['enable']) && $xhprof_config['enable']()) {
+        xhprof_enable(XHPROF_FLAGS_MEMORY | XHPROF_FLAGS_CPU);
+        register_shutdown_function(function() use ($xhprof_config){
+            $xhprof_data	= xhprof_disable();
+            if (function_exists('fastcgi_finish_request')) {
+                fastcgi_finish_request();
+            }
+            require_once __DIR__ . '/../xhprof/classes/data.php';
+            $xhprof_data_obj	= new \ay\xhprof\Data($xhprof_config['pdo']);
+            $xhprof_data_obj->save($xhprof_data);
+        });
+    }
+}

xhprof/includes/config.inc.sample.php

@@ -3,4 +3,11 @@
 	'url_base' => 'https://dev.anuary.com/8d50658e-f8e0-5832-9e82-6b9e8aa940ac/',
 	'url_static' => null, // When undefined, it defaults to $config['url_base'] . 'public/'. This should be absolute URL.
 	'pdo' => new PDO('mysql:dbname=your_database_name;host=localhost;charset=utf8', 'username', 'password'),
-);
+    'enable' => function() {
+        //enable for 1/100 probability
+        //return rand(0, 100) === 42;
+
+        //enable always
+        return true;
+    }
+);