From c3f5624f8d53d045990029150db030ed58e788c2 Mon Sep 17 00:00:00 2001
From: William <william@willy.club>
Date: Sun, 27 Mar 2022 22:19:01 +0000
Subject: [PATCH] Commit

---
 app/lib/App/SSE/EventLoop.php              | 79 ++++++++++++++++++++++
 app/lib/App/SSE/Sender.php                 | 39 -----------
 app/lib/App/SSE/StopEventLoopException.php | 10 +++
 app/view/pages/race/live-results.php       | 18 ++---
 public/race/stream.php                     | 41 ++++++-----
 5 files changed, 117 insertions(+), 70 deletions(-)
 create mode 100644 app/lib/App/SSE/EventLoop.php
 delete mode 100644 app/lib/App/SSE/Sender.php
 create mode 100644 app/lib/App/SSE/StopEventLoopException.php

diff --git a/app/lib/App/SSE/EventLoop.php b/app/lib/App/SSE/EventLoop.php
new file mode 100644
index 0000000..f2767f7
--- /dev/null
+++ b/app/lib/App/SSE/EventLoop.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace App\SSE;
+
+/**
+ * Small class to abstract Server-Sent Events (SSE)
+ * 
+ * https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events
+ */
+class EventLoop 
+{
+    public int $interval  = 3;
+
+    public int $heartbeat = 5; // send heartbeat every num seconds to ensure connection is still alive
+    public int $timeLimit = 3600;
+    public int $execLimit = 30;
+
+    public function start(callable $callback): void
+    {
+        // as session data is locked to prevent concurrent writes we
+        // make it read only to prevent the server from locking up
+        if (session_status() === PHP_SESSION_ACTIVE)
+        {
+            session_write_close();
+        }
+
+        header("Cache-Control: no-store");
+        header("Content-Type: text/event-stream");
+        header('X-Accel-Buffering: no'); // for nginx buffering
+
+        // send headers to client indicating we are now a stream
+        ob_end_flush();
+        flush();
+
+        $expirationTime = time() + $this->timeLimit;
+
+        $lastHeartbeat = time();
+
+        while (!connection_aborted() && time() < $expirationTime)
+        {
+            set_time_limit($this->execLimit);
+            try {
+                $data = call_user_func($callback);
+                if ($data !== NULL)
+                {
+                    $this->send($data);
+                    $lastHeartbeat = time();
+                }
+            } catch (StopEventLoopException $th) {
+                break;
+            }
+
+            // sleep and perform heartbeat to ensure connection is still alive
+            for ($i = 0; $i < $this->interval; $i++)
+            {
+                if (time() >= $lastHeartbeat + $this->heartbeat)
+                {
+                    echo ": \n\n";
+                    ob_end_flush();
+                    flush();
+                    $lastHeartbeat = time();
+                }
+                sleep(1);
+            }
+        }
+    }
+
+    /**
+     * Send data to client encoded as json
+     */
+    private function send($data): void
+    {
+        echo "data: " . json_encode($data);
+        echo "\n\n";
+        // send data to stream
+        ob_end_flush();
+        flush();
+    }
+}
\ No newline at end of file
diff --git a/app/lib/App/SSE/Sender.php b/app/lib/App/SSE/Sender.php
deleted file mode 100644
index 6eb59d0..0000000
--- a/app/lib/App/SSE/Sender.php
+++ /dev/null
@@ -1,39 +0,0 @@
-<?php
-
-namespace App\SSE;
-
-/**
- * Small class to abstract Server-Sent Events (SSE)
- * 
- * https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events
- */
-class Sender 
-{
-    public function start(): void
-    {
-        header("Cache-Control: no-store");
-        header("Content-Type: text/event-stream");
-
-        // as session data is locked to prevent concurrent writes we
-        // make it read only to prevent the server from locking up
-        session_write_close();
-
-        // we have to flush before because idk
-        ob_end_flush();
-        flush();
-    }
-
-    public function flush($data, $event = NULL): void
-    {
-        if ($event)
-        {
-            echo "event: $event\n";
-        }
-        echo "data: " . json_encode($data) ."";
-        echo "\n\n";
-
-        // send data to stream
-        ob_end_flush();
-        flush();
-    }
-}
\ No newline at end of file
diff --git a/app/lib/App/SSE/StopEventLoopException.php b/app/lib/App/SSE/StopEventLoopException.php
new file mode 100644
index 0000000..7b2673a
--- /dev/null
+++ b/app/lib/App/SSE/StopEventLoopException.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace App\SSE;
+
+use \Exception;
+
+class StopEventLoopException extends Exception
+{
+    // not much here...
+}
\ No newline at end of file
diff --git a/app/view/pages/race/live-results.php b/app/view/pages/race/live-results.php
index e9a3e0b..158682e 100644
--- a/app/view/pages/race/live-results.php
+++ b/app/view/pages/race/live-results.php
@@ -8,19 +8,9 @@
 </table>
 
 <script>
-var source = new EventSource('stream.php');
-
-source.addEventListener('message', function(e)
+var es = new EventSource('stream.php');
+es.onmessage = function(event)
 {
-    rows = JSON.parse(e.data);
-    console.log(rows);
-
-    // update table
-    root = document.getElementById("root");
-    rows.forEach(row => root.insertAdjacentHTML(
-        'beforebegin',
-        `<tr><td>${row.teamId}</td><td>${row.id}</td></tr>`
-    ));
-
-}, false);
+    console.log("New message", event.data);
+};
 </script>
\ No newline at end of file
diff --git a/public/race/stream.php b/public/race/stream.php
index ad78da4..e16a045 100644
--- a/public/race/stream.php
+++ b/public/race/stream.php
@@ -2,33 +2,40 @@
 
 use App\Teamtable\TeamMapper;
 use App\Timetable\TimeMapper;
-use App\SSE\Sender;
+use App\SSE\EventLoop;
+use App\SSE\StopEventLoopException;
 
 $teamMapper = new TimeMapper($app->database->conn);
 $timeMapper = new TimeMapper($app->database->conn);
 
 /**
- * Server-Sent Events (SSE)
+ * Send events to client with Server-Sent Events(SSE)
  */
-$sse = new Sender();
-$sse->start();
+$sse = new EventLoop();
+$sse->interval = 1; 
 
-$prev_last_insert = NULL;
-while (!connection_aborted())
-{
-    $time = $timeMapper->getLatest();
+$persist_obj = new class {
+        public ?int $prev_last_insert = NULL;
+    };
 
-    if ($time)
-    {
-        $last_insert = $time->date->getTimestamp();
+$sse->start(
+    function () use ($timeMapper, $teamMapper, &$persist_obj) {
 
-        if ($prev_last_insert == NULL || $last_insert > $prev_last_insert)
+        $time = $timeMapper->getLatest();
+
+        if ($time)
         {
-            $sse->flush($timeMapper->getAll());
+            $last_insert = $time->date->getTimestamp();
 
-            $prev_last_insert = $last_insert;
+            if ( $persist_obj->prev_last_insert == NULL
+                || $last_insert > $persist_obj->prev_last_insert
+            ) {
+                $persist_obj->prev_last_insert = $last_insert;
+
+                return($timeMapper->getAll());
+            }
         }
-    }
 
-    sleep(1);
-}
\ No newline at end of file
+        return;
+    }
+);
\ No newline at end of file