79 lines
2.1 KiB
PHP
79 lines
2.1 KiB
PHP
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<?php
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namespace App\SSE;
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/**
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* Small class to abstract Server-Sent Events (SSE)
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*
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* https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events
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*/
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class EventLoop
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{
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public int $interval = 3;
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public int $heartbeat = 5; // send heartbeat every num seconds to ensure connection is still alive
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public int $timeLimit = 3600;
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public int $execLimit = 30;
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public function start(callable $callback): void
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{
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// as session data is locked to prevent concurrent writes we
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// make it read only to prevent the server from locking up
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if (session_status() === PHP_SESSION_ACTIVE)
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{
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session_write_close();
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}
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header("Cache-Control: no-store");
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header("Content-Type: text/event-stream");
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header('X-Accel-Buffering: no'); // for nginx buffering
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// send headers to client indicating we are now a stream
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ob_end_flush();
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flush();
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$expirationTime = time() + $this->timeLimit;
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$lastHeartbeat = time();
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while (!connection_aborted() && time() < $expirationTime)
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{
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set_time_limit($this->execLimit);
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try {
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$data = call_user_func($callback);
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if ($data !== NULL)
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{
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$this->send($data);
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$lastHeartbeat = time();
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}
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} catch (StopEventLoopException $th) {
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break;
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}
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// sleep and perform heartbeat to ensure connection is still alive
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for ($i = 0; $i < $this->interval; $i++)
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{
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if (time() >= $lastHeartbeat + $this->heartbeat)
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{
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echo ": \n\n";
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ob_end_flush();
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flush();
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$lastHeartbeat = time();
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}
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sleep(1);
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}
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}
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}
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/**
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* Send data to client encoded as json
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*/
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private function send($data): void
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{
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echo "data: " . json_encode($data);
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echo "\n\n";
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// send data to stream
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ob_end_flush();
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flush();
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}
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}
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