SSE not logging disconnect - php

Question

I currently have a simple SSE page for testing. I can currently get the page to log when a user connects and while they are connected; however, when the page closes it seems (eg user disconnects) it doesnt log anything. I am using the function error_log for logging. Also, using NGINX and PHP 7.2. Here is my code:
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
header('X-Accel-Buffering: no');
ignore_user_abort(true);
$aid = 1;
function sendMsg($id , $msg) {
echo "id: $id" . PHP_EOL;
echo "data: " . json_encode(array('x'=> $msg)) . PHP_EOL;
echo "retry: 0" . PHP_EOL;
echo PHP_EOL;
#ob_end_flush();
flush();
}//END FUNCTION sendMsg
function endPacket() {
echo "0\r\n\r\n";
#ob_end_flush();
flush();
}//END FUNCTION endPacket
$startedAt = time();
error_log("Starting SSE to User: " . $aid);
while (true) {
set_time_limit(15);
if ( connection_status() != 0 ) {
error_log("Ending SSE to User: " . $aid);
endPacket();
die();
}//END IF
error_log("Connected SSE as User: " . $aid);
sendMsg( $startedAt, $aid . ' | ' . connection_status() );
sleep(10);
}//END WHILE

Answer 1

Your code is failing to detect a disconnect because you need to write to the user before you can detect a disconnect
While it looks like your demo code does this, it actually doesn't. This is what your code does now:
detect_connection();
sendMsg();
sleep();
detect_connection();
sendMsg();
<timeout>
The only way in your example to trigger the connection disconnect message is if the connection is closed the first time you call "sendMsg()", what probably is not going to happen as you are not that quick