Add the bulk of the implementation code

composer.json

@@ -14,6 +14,7 @@
     "autoload": {
         "psr-4": {
             "TenUp\\AsyncTransients\\": "includes/TenUp/AsyncTransients"
-        }
+        },
+        "files": [ "includes/helpers.php" ]
     }
 }

includes/TenUp/AsyncTransients/AsyncTransient.php

@@ -2,8 +2,137 @@
 
 namespace TenUp\AsyncTransients;
 
-class AsyncTransient {
+class Transient {
 
+	protected static $_instance;
 
+	protected $queue;
+
+	public static function instance() {
+		if ( is_null( self::$_instance ) ) {
+			self::$_instance = new static();
+			self::$_instance->setup();
+		}
+
+		return self::$_instance;
+	}
+
+	public function __construct() {
+		$this->queue = array();
+	}
+
+	public function setup() {
+		add_action( 'shutdown', array( $this, 'finish_request' ), 100 );
+	}
+
+	/**
+	 * If using fastcgi, close the request to the browser and process all the queued transient regeneration callbacks
+	 */
+	public function finish_request() {
+		// Bail if we don't have fastcgi_finish_request
+		// Nothing should be in the queue anyways, since we don't add to queue if this function is not available
+		// See $this->add_to_queue()
+		if ( ! function_exists( 'fastcgi_finish_request' ) ) {
+			return;
+		}
+
+		fastcgi_finish_request();
+		set_time_limit( 0 );
+
+		foreach( $this->queue as $item ) {
+			call_user_func_array( $item['function'], $item['params'] );
+		}
+
+		exit;
+	}
+
+	public function delete( $transient ) {
+		$option_timeout = '_async_transient_timeout_' . $transient;
+		$option = '_async_transient_' . $transient;
+		$result = delete_option( $option );
+		if ( $result ) {
+			delete_option( $option_timeout );
+		}
+
+		return $result;
+	}
+
+	public function get( $transient, $regenerate_function, $regenerate_params = array() ) {
+		$regenerate = false;
+		$transient_option = '_async_transient_' . $transient;
+
+		// If option is not in alloptions, it is not autoloaded and thus has a timeout
+		$alloptions = wp_load_alloptions();
+		if ( ! isset( $alloptions[ $transient_option ] ) ) {
+			$transient_timeout = '_async_transient_timeout_' . $transient;
+			$timeout = get_option( $transient_timeout );
+			if ( false !== $timeout && $timeout < time() ) {
+				$regenerate = true;
+
+			}
+		}
+
+		$value = get_option( $transient_option );
+		if ( $value === false ) {
+			$regenerate = true;
+		}
+
+		if ( $regenerate === true ) {
+			// Set this up to be refreshed later
+			$this->add_to_queue( $regenerate_function, $regenerate_params );
+		}
+
+		return $value;
+	}
+
+	public function set( $transient, $value, $expiration ) {
+		$expiration = (int) $expiration;
+
+		$transient_timeout = '_async_transient_timeout_' . $transient;
+		$transient_option = '_async_transient_' . $transient;
+		if ( false === get_option( $transient_option ) ) {
+			$autoload = 'yes';
+			if ( $expiration ) {
+				$autoload = 'no';
+				add_option( $transient_timeout, time() + $expiration, '', 'no' );
+			}
+			$result = add_option( $transient_option, $value, '', $autoload );
+		} else {
+			// If expiration is requested, but the transient has no timeout option,
+			// delete, then re-create transient rather than update.
+			$update = true;
+			if ( $expiration ) {
+				if ( false === get_option( $transient_timeout ) ) {
+					delete_option( $transient_option );
+					add_option( $transient_timeout, time() + $expiration, '', 'no' );
+					$result = add_option( $transient_option, $value, '', 'no' );
+					$update = false;
+				} else {
+					update_option( $transient_timeout, time() + $expiration );
+				}
+			}
+			if ( $update ) {
+				$result = update_option( $transient_option, $value );
+			}
+		}
+
+		return $result;
+	}
+
+	public function add_to_queue( $function, $params_array ) {
+		if ( function_exists( 'fastcgi_finish_request' ) ) {
+			// Make sure this is unique
+			$hash = md5( $function . json_encode( $params_array ) );
+			if ( ! isset( $this->queue[ $hash ] ) ) {
+				$this->queue[ $hash ] = array(
+					'function' => $function,
+					'params' => $params_array,
+				);
+			}
+		} else {
+			// We don't have fastcgi_finish_request available, so refresh the transient now instead of queuing it for later.
+			call_user_func_array( $function, $params_array );
+		}
+	}
 
 }

includes/helpers.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace TenUp\AsyncTransients;
+
+function delete_async_transient( $transient ) {
+	return Transient::instance()->delete( $transient );
+}
+
+function get_async_transient( $transient, $regenerate_function, $regenerate_params = array() ) {
+	return Transient::instance()->get( $transient, $regenerate_function, $regenerate_params );
+}
+
+function set_async_transient( $transient, $value, $expiration ) {
+	return Transient::instance()->set( $transient, $value, $expiration );
+}