storeengine / includes / classes / event-stream-server.php

event-stream-server.php in StoreEngine — Complete eCommerce Solution with Memberships, Licensing, Affiliates & More 2.2.0, at includes/classes/event-stream-server.php

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1	<?php
2	/**
3	* A lightweight server-sent event (SSE) handler for streaming real-time data to browsers using EventSource.
4	*
5	* @version 1.0.0
6	*/
7
8	namespace StoreEngine\Classes;
9
10	use StoreEngine\Utils\Helper;
11
12	if ( ! defined( 'ABSPATH' ) ) {
13	exit;
14	}
15
16	/**
17	* Class EventStreamServer
18	*
19	* A lightweight server-sent event (SSE) handler for streaming real-time data to browsers using EventSource.
20	*
21	* @example
22	* ```php
23	* $sse = new EventStreamServer();
24	* $sse->listen(function () use ($sse) {
25	* $sse->emitEvent([
26	* 'event' => 'ping',
27	* 'message' => 'hello',
28	* 'time' => current_time('mysql'),
29	* ]);
30	*
31	* // Optionally close stream under a condition
32	* if ( some_condition() ) {
33	* $sse->emitEvent([
34	* 'event' => 'end',
35	* 'message' => 'done',
36	* ], true);
37	* }
38	* });
39	* ```
40	*/
41	class EventStreamServer {
42
43	/**
44	* Whether the connection should remain open.
45	*
46	* @var bool
47	*/
48	private bool $connected = true;
49
50	/**
51	* @var int
52	*/
53	private int $id = 0;
54
55	private bool $is_reconnect = false;
56
57	/**
58	* Prepares the HTTP headers and environment for a Server-Sent Events stream.
59	*
60	* Disables buffering and compression, sets correct headers, and ends any existing output buffers.
61	*/
62	protected function setupHeaders(): void {
63	// phpcs:disable
64	$previous = error_reporting( error_reporting() ^ E_WARNING ); // Disable warnings temporarily
65
66	// Required headers for SSE
67	header( 'Content-Type: text/event-stream' );
68	header( 'Cache-Control: no-cache' );
69	header( 'Connection: keep-alive' );
70
71	// Prevent Apache buffering
72	if ( function_exists( 'apache_setenv' ) ) {
73	@apache_setenv( 'no-gzip', 1 );
74	}
75
76	// Disable PHP buffering
77	@ini_set( 'output_buffering', 'off' );
78	@ini_set( 'zlib.output_compression', 0 );
79	@ini_set( 'implicit_flush', 1 );
80
81	// NGINX-specific buffering control
82	if ( ! empty( $_SERVER['SERVER_SOFTWARE'] ) && stripos( $_SERVER['SERVER_SOFTWARE'], 'nginx' ) !== false ) {
83	header( 'X-Accel-Buffering: no' );
84	header( 'Content-Encoding: none' );
85	}
86
87
88	$this->id = intval( wp_unslash( $_SERVER['HTTP_LAST_EVENT_ID'] ?? 0 ) );
89	$this->is_reconnect = isset( $_SERVER['HTTP_LAST_EVENT_ID'] );
90
91	// Restore error reporting previous state.
92	error_reporting( $previous );
93
94	// Prevent script timeout
95	set_time_limit( 0 );
96
97	// Clean existing output buffers
98	while ( ob_get_level() != 0 ) {
99	ob_end_flush();
100	}
101
102	ob_implicit_flush( 1 );
103	flush();
104
105	// phpcs:enable
106	}
107
108	/**
109	* Starts the event stream and repeatedly invokes the provided callback.
110	*
111	* The callback should use emitEvent() to send data to the client.
112	*
113	* @param callable $callback The function that emits events. Called continuously while connected.
114	*/
115	public function listen( callable $callback ): void {
116	$this->setupHeaders();
117
118	// Initial padding to prevent browser-side buffering (especially in IE)
119	echo ':' . str_repeat( ' ', 2048 ) . "\n\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
120	flush();
121
122	$start = time();
123
124	echo 'retry: ' . 1000 . "\n";
125
126	while ( $this->connected ) {
127	$upTime = ( time() - $start );
128
129	if ( $upTime % 300 === 0 ) {
130	// No updates needed, send a comment to keep the connection alive.
131	// From https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events
132	echo ': ' . sha1( wp_rand() ) . "\n\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
133	}
134
135	try {
136	call_user_func( $callback );
137	} catch ( \Exception $e ) {
138	Helper::log_error( $e );
139
140	$this->emitEvent( [
141	'event' => 'error',
142	'message' => $e->getMessage(),
143	'code' => $e->getCode(),
144	] );
145	}
146
147	@ob_flush();
148	flush();
149
150	// if the connection has been closed by the client we better exit the loop
151	if ( connection_aborted() \|\| $upTime > 600 ) {
152	break;
153	}
154
155	// Prevent tight infinite loop
156	usleep( 100000 ); // 0.1 second
157	}
158	}
159
160	public function terminate(): void {
161	$this->connected = false;
162	sleep( 1 ); // Delay to allow client to receive final message
163	exit;
164	}
165
166	/**
167	* Emits a Server-Sent Event to the client.
168	*
169	* @param array $data {
170	* The data to send in the event.
171	*
172	* @type string $event Optional. The event name. Defaults to 'message'.
173	* @type string $type Optional. message type for js.
174	* @type mixed $n Additional fields included as JSON in the data payload.
175	* }
176	*
177	* @param bool $terminate Optional. Whether to terminate the connection after sending. Default false.
178	*
179	* @return void
180	*/
181	public function emitEvent( array $data = [], bool $terminate = false ): void {
182	$event = esc_attr( $data['event'] ?? 'message' );
183	unset( $data['event'] );
184
185	echo "id: {$this->getNewId()}\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- integer escaping!
186	echo "event: {$event}\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
187	echo 'data: ' . wp_json_encode( $data ) . "\n\n";
188
189	// Browser padding for IE
190	echo ':' . str_repeat( ' ', 2048 ) . "\n\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
191
192	@ob_flush();
193	flush();
194
195	if ( $terminate ) {
196	$this->terminate();
197	}
198	}
199
200	public function getNewId(): int {
201	return $this->id ++;
202	}
203	}
204
205	// End of file event-stream-server.php.
206