From 0629d11e130ba3d9b2b240c97dfbecfa79e121a1 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <dktapps@pmmp.io>
Date: Sun, 16 Apr 2023 20:51:55 +0100
Subject: [PATCH] Avoid unnecessary events work in handleDataPacket if the
 events have no registered handlers this particular optimisation became
 possible thanks to changes in 4.19.

I observed that the allocation of Event objects and calling ->call() was costing us a significant percentage of the time taken in PlayerAuthInputPacket handlers. This change produces a measurable 2 microsecond reduction in overhead for PlayerAuthInputPacket handling when players are not moving (10.7 -> 8.7 microseconds). On a server with 200 players, this translates into a 1% reduction in CPU load for PlayerAuthInputPacket alone. It will also benefit other packets, but not to the extent that PlayerAuthInputPacket benefits.
---
 src/event/Event.php                 | 11 +++++++++
 src/network/mcpe/NetworkSession.php | 35 ++++++++++++++++-------------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/src/event/Event.php b/src/event/Event.php
index 1ae7bb96f..6264d8525 100644
--- a/src/event/Event.php
+++ b/src/event/Event.php
@@ -27,6 +27,7 @@ declare(strict_types=1);
 namespace pocketmine\event;
 
 use pocketmine\timings\Timings;
+use function count;
 use function get_class;
 
 abstract class Event{
@@ -67,4 +68,14 @@ abstract class Event{
 			$timings->stopTiming();
 		}
 	}
+
+	/**
+	 * Returns whether the current class context has any registered global handlers.
+	 * This can be used in hot code paths to avoid unnecessary event object creation.
+	 *
+	 * Usage: SomeEventClass::hasHandlers()
+	 */
+	public static function hasHandlers() : bool{
+		return count(HandlerListManager::global()->getListFor(static::class)->getListenerList()) > 0;
+	}
 }
diff --git a/src/network/mcpe/NetworkSession.php b/src/network/mcpe/NetworkSession.php
index 7f07fbd77..dfba61bab 100644
--- a/src/network/mcpe/NetworkSession.php
+++ b/src/network/mcpe/NetworkSession.php
@@ -401,10 +401,12 @@ class NetworkSession{
 		$timings->startTiming();
 
 		try{
-			$ev = new DataPacketDecodeEvent($this, $packet->pid(), $buffer);
-			$ev->call();
-			if($ev->isCancelled()){
-				return;
+			if(DataPacketDecodeEvent::hasHandlers()){
+				$ev = new DataPacketDecodeEvent($this, $packet->pid(), $buffer);
+				$ev->call();
+				if($ev->isCancelled()){
+					return;
+				}
 			}
 
 			$decodeTimings = Timings::getDecodeDataPacketTimings($packet);
@@ -424,19 +426,22 @@ class NetworkSession{
 				$decodeTimings->stopTiming();
 			}
 
-			$ev = new DataPacketReceiveEvent($this, $packet);
-			$ev->call();
-			if(!$ev->isCancelled()){
-				$handlerTimings = Timings::getHandleDataPacketTimings($packet);
-				$handlerTimings->startTiming();
-				try{
-					if($this->handler === null || !$packet->handle($this->handler)){
-						$this->logger->debug("Unhandled " . $packet->getName() . ": " . base64_encode($stream->getBuffer()));
-					}
-				}finally{
-					$handlerTimings->stopTiming();
+			if(DataPacketReceiveEvent::hasHandlers()){
+				$ev = new DataPacketReceiveEvent($this, $packet);
+				$ev->call();
+				if($ev->isCancelled()){
+					return;
 				}
 			}
+			$handlerTimings = Timings::getHandleDataPacketTimings($packet);
+			$handlerTimings->startTiming();
+			try{
+				if($this->handler === null || !$packet->handle($this->handler)){
+					$this->logger->debug("Unhandled " . $packet->getName() . ": " . base64_encode($stream->getBuffer()));
+				}
+			}finally{
+				$handlerTimings->stopTiming();
+			}
 		}finally{
 			$timings->stopTiming();
 		}