Buffer slot and content syncing until the end of the tick

we may receive multiple requests in one tick (e.g. crafting in a batch)

src/network/mcpe/InventoryManager.php

@@ -59,8 +59,11 @@ use pocketmine\network\PacketHandlingException;
 use pocketmine\player\Player;
 use pocketmine\utils\AssumptionFailedError;
 use pocketmine\utils\ObjectSet;
+use function array_keys;
 use function array_search;
+use function count;
 use function get_class;
+use function implode;
 use function is_int;
 use function max;
 use function spl_object_id;
@@ -100,6 +103,8 @@ class InventoryManager{
 	private int $nextItemStackId = 1;
 	private ?int $currentItemStackRequestId = null;
 
+	private bool $fullSyncRequested = false;
+
 	public function __construct(
 		private Player $player,
 		private NetworkSession $session
@@ -400,7 +405,7 @@ class InventoryManager{
 		if($clientSideItem === null || !$clientSideItem->equals($currentItem)){
 			//no prediction or incorrect - do not associate this with the currently active itemstack request
 			$this->trackItemStack($inventory, $slot, $currentItem, null);
-			$this->syncSlot($inventory, $slot);
+			$inventoryEntry->pendingSyncs[$slot] = $slot;
 		}else{
 			//correctly predicted - associate the change with the currently active itemstack request
 			$this->trackItemStack($inventory, $slot, $currentItem, $this->currentItemStackRequestId);
@@ -452,7 +457,7 @@ class InventoryManager{
 			}
 			$this->session->sendDataPacket(InventorySlotPacket::create($windowId, $netSlot, $itemStackWrapper));
 		}
-		unset($entry->predictions[$slot]);
+		unset($entry->predictions[$slot], $entry->pendingSyncs[$slot]);
 	}
 
 	public function syncContents(Inventory $inventory) : void{
@@ -464,6 +469,7 @@ class InventoryManager{
 		}
 		if($windowId !== null){
 			$entry->predictions = [];
+			$entry->pendingSyncs = [];
 			$contents = [];
 			foreach($inventory->getContents(true) as $slot => $item){
 				$itemStack = TypeConverter::getInstance()->coreItemStackToNet($item);
@@ -494,6 +500,10 @@ class InventoryManager{
 		}
 	}
 
+	public function requestSyncAll() : void{
+		$this->fullSyncRequested = true;
+	}
+
 	public function syncMismatchedPredictedSlotChanges() : void{
 		foreach($this->inventories as $entry){
 			$inventory = $entry->inventory;
@@ -504,13 +514,33 @@ class InventoryManager{
 
 				//any prediction that still exists at this point is a slot that was predicted to change but didn't
 				$this->session->getLogger()->debug("Detected prediction mismatch in inventory " . get_class($inventory) . "#" . spl_object_id($inventory) . " slot $slot");
-				$this->syncSlot($inventory, $slot);
+				$entry->pendingSyncs[$slot] = $slot;
 			}
 
 			$entry->predictions = [];
 		}
 	}
 
+	public function flushPendingUpdates() : void{
+		if($this->fullSyncRequested){
+			$this->fullSyncRequested = false;
+			$this->session->getLogger()->debug("Full inventory sync requested, sending contents of " . count($this->inventories) . " inventories");
+			$this->syncAll();
+		}else{
+			foreach($this->inventories as $entry){
+				if(count($entry->pendingSyncs) === 0){
+					continue;
+				}
+				$inventory = $entry->inventory;
+				$this->session->getLogger()->debug("Syncing slots " . implode(", ", array_keys($entry->pendingSyncs)) . " in inventory " . get_class($inventory) . "#" . spl_object_id($inventory));
+				foreach($entry->pendingSyncs as $slot){
+					$this->syncSlot($inventory, $slot);
+				}
+				$entry->pendingSyncs = [];
+			}
+		}
+	}
+
 	public function syncData(Inventory $inventory, int $propertyId, int $value) : void{
 		$windowId = $this->getWindowId($inventory);
 		if($windowId !== null){

src/network/mcpe/InventoryManagerEntry.php

@@ -39,6 +39,12 @@ final class InventoryManagerEntry{
 	 */
 	public array $itemStackInfos = [];
 
+	/**
+	 * @var int[]
+	 * @phpstan-var array<int, int>
+	 */
+	public array $pendingSyncs = [];
+
 	public function __construct(
 		public Inventory $inventory,
 		public ?ComplexInventoryMapEntry $complexSlotMap = null

src/network/mcpe/NetworkSession.php

@@ -1219,6 +1219,7 @@ class NetworkSession{
 				$attribute->markSynchronized();
 			}
 		}
+		$this->invManager?->flushPendingUpdates();
 
 		$this->flushSendBuffer();
 	}

src/network/mcpe/handler/InGamePacketHandler.php

@@ -35,7 +35,8 @@ use pocketmine\event\player\PlayerEditBookEvent;
 use pocketmine\inventory\transaction\action\DropItemAction;
 use pocketmine\inventory\transaction\InventoryTransaction;
 use pocketmine\inventory\transaction\TransactionBuilder;
-use pocketmine\inventory\transaction\TransactionException;
+use pocketmine\inventory\transaction\TransactionCancelledException;
+use pocketmine\inventory\transaction\TransactionValidationException;
 use pocketmine\item\VanillaItems;
 use pocketmine\item\WritableBook;
 use pocketmine\item\WritableBookPage;
@@ -335,7 +336,7 @@ class InGamePacketHandler extends PacketHandler{
 			$result = $this->handleNormalTransaction($packet->trData, $packet->requestId);
 		}elseif($packet->trData instanceof MismatchTransactionData){
 			$this->session->getLogger()->debug("Mismatch transaction received");
-			$this->inventoryManager->syncAll();
+			$this->inventoryManager->requestSyncAll();
 			$result = true;
 		}elseif($packet->trData instanceof UseItemTransactionData){
 			$result = $this->handleUseItemTransaction($packet->trData);
@@ -357,9 +358,14 @@ class InGamePacketHandler extends PacketHandler{
 		$this->inventoryManager->addTransactionPredictedSlotChanges($transaction);
 		try{
 			$transaction->execute();
-		}catch(TransactionException $e){
+		}catch(TransactionValidationException $e){
+			$this->inventoryManager->requestSyncAll();
 			$logger = $this->session->getLogger();
-			$logger->debug("Failed to execute inventory transaction: " . $e->getMessage());
+			$logger->debug("Invalid inventory transaction $requestId: " . $e->getMessage());
+
+			return false;
+		}catch(TransactionCancelledException){
+			$this->session->getLogger()->debug("Inventory transaction $requestId cancelled by a plugin");
 
 			return false;
 		}finally{
@@ -538,6 +544,7 @@ class InGamePacketHandler extends PacketHandler{
 			$result = false;
 			$this->session->getLogger()->debug("ItemStackRequest #" . $request->getRequestId() . " failed: " . $e->getMessage());
 			$this->session->getLogger()->debug(implode("\n", Utils::printableExceptionInfo($e)));
+			$this->inventoryManager->requestSyncAll();
 		}
 
 		if(!$result){