From c85239307604282e5b5937f60b5cec7ea820ede7 Mon Sep 17 00:00:00 2001
From: IntegratedQuantum <43880493+IntegratedQuantum@users.noreply.github.com>
Date: Wed, 21 May 2025 20:42:17 +0200
Subject: [PATCH] Refactor how block entity unloading works and unloading
 things on the client side (#1475)

extracted from #1446
---
 src/block_entity.zig           | 32 ++++++++++++++++++++------------
 src/chunk.zig                  | 21 +++++++++++++++++++++
 src/renderer/chunk_meshing.zig |  1 +
 3 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/src/block_entity.zig b/src/block_entity.zig
index 993acdf4..bc9b41c7 100644
--- a/src/block_entity.zig
+++ b/src/block_entity.zig
@@ -18,9 +18,9 @@ pub const BlockEntityType = struct {
 
 	const VTable = struct {
 		onLoadClient: *const fn(pos: Vec3i, chunk: *Chunk) void,
-		onUnloadClient: *const fn(pos: Vec3i, chunk: *Chunk) void,
+		onUnloadClient: *const fn(dataIndex: BlockEntityIndex) void,
 		onLoadServer: *const fn(pos: Vec3i, chunk: *Chunk) void,
-		onUnloadServer: *const fn(pos: Vec3i, chunk: *Chunk) void,
+		onUnloadServer: *const fn(dataIndex: BlockEntityIndex) void,
 		onPlaceClient: *const fn(pos: Vec3i, chunk: *Chunk) void,
 		onBreakClient: *const fn(pos: Vec3i, chunk: *Chunk) void,
 		onPlaceServer: *const fn(pos: Vec3i, chunk: *Chunk) void,
@@ -45,14 +45,14 @@ pub const BlockEntityType = struct {
 	pub inline fn onLoadClient(self: *BlockEntityType, pos: Vec3i, chunk: *Chunk) void {
 		return self.vtable.onLoadClient(pos, chunk);
 	}
-	pub inline fn onUnloadClient(self: *BlockEntityType, pos: Vec3i, chunk: *Chunk) void {
-		return self.vtable.onUnloadClient(pos, chunk);
+	pub inline fn onUnloadClient(self: *BlockEntityType, dataIndex: BlockEntityIndex) void {
+		return self.vtable.onUnloadClient(dataIndex);
 	}
 	pub inline fn onLoadServer(self: *BlockEntityType, pos: Vec3i, chunk: *Chunk) void {
 		return self.vtable.onLoadServer(pos, chunk);
 	}
-	pub inline fn onUnloadServer(self: *BlockEntityType, pos: Vec3i, chunk: *Chunk) void {
-		return self.vtable.onUnloadServer(pos, chunk);
+	pub inline fn onUnloadServer(self: *BlockEntityType, dataIndex: BlockEntityIndex) void {
+		return self.vtable.onUnloadServer(dataIndex);
 	}
 	pub inline fn onPlaceClient(self: *BlockEntityType, pos: Vec3i, chunk: *Chunk) void {
 		return self.vtable.onPlaceClient(pos, chunk);
@@ -117,6 +117,13 @@ fn BlockEntityDataStorage(T: type) type {
 			chunk.blockPosToEntityDataMap.put(main.globalAllocator.allocator, blockIndex, @intCast(dataIndex)) catch unreachable;
 			chunk.blockPosToEntityDataMapMutex.unlock();
 		}
+		pub fn removeAtIndex(dataIndex: BlockEntityIndex) void {
+			main.utils.assertLocked(&mutex);
+			freeIndexList.append(main.globalAllocator, dataIndex);
+			storage.remove(dataIndex) catch |err| {
+				std.log.err("Error while removing block entity: {s}", .{@errorName(err)});
+			};
+		}
 		pub fn remove(pos: Vec3i, chunk: *Chunk) void {
 			mutex.lock();
 			defer mutex.unlock();
@@ -133,10 +140,7 @@ fn BlockEntityDataStorage(T: type) type {
 			};
 
 			const dataIndex = entry.value;
-			freeIndexList.append(main.globalAllocator, dataIndex);
-			storage.remove(dataIndex) catch |err| {
-				std.log.err("Error while remvoing block entity at position {}: {s}", .{pos, @errorName(err)});
-			};
+			removeAtIndex(dataIndex);
 		}
 		pub fn get(pos: Vec3i, chunk: *Chunk) ?*DataT {
 			main.utils.assertLocked(&mutex);
@@ -175,9 +179,13 @@ pub const BlockEntityTypes = struct {
 		}
 
 		pub fn onLoadClient(_: Vec3i, _: *Chunk) void {}
-		pub fn onUnloadClient(_: Vec3i, _: *Chunk) void {}
+		pub fn onUnloadClient(_: BlockEntityIndex) void {}
 		pub fn onLoadServer(_: Vec3i, _: *Chunk) void {}
-		pub fn onUnloadServer(_: Vec3i, _: *Chunk) void {}
+		pub fn onUnloadServer(dataIndex: BlockEntityIndex) void {
+			StorageServer.mutex.lock();
+			defer StorageServer.mutex.unlock();
+			StorageServer.removeAtIndex(dataIndex);
+		}
 		pub fn onPlaceClient(_: Vec3i, _: *Chunk) void {}
 		pub fn onBreakClient(_: Vec3i, _: *Chunk) void {}
 		pub fn onPlaceServer(_: Vec3i, _: *Chunk) void {}
diff --git a/src/chunk.zig b/src/chunk.zig
index aa86b689..2665e7b9 100644
--- a/src/chunk.zig
+++ b/src/chunk.zig
@@ -284,6 +284,27 @@ pub const Chunk = struct { // MARK: Chunk
 		memoryPool.destroy(@alignCast(self));
 	}
 
+	pub fn unloadBlockEntities(self: *Chunk, comptime side: main.utils.Side) void {
+		self.blockPosToEntityDataMapMutex.lock();
+		defer self.blockPosToEntityDataMapMutex.unlock();
+		var iterator = self.blockPosToEntityDataMap.iterator();
+		while(iterator.next()) |elem| {
+			const index = elem.key_ptr.*;
+			const entityDataIndex = elem.value_ptr.*;
+			const block = self.data.getValue(index);
+			const blockEntity = block.blockEntity() orelse unreachable;
+			switch(side) {
+				.client => {
+					blockEntity.onUnloadClient(entityDataIndex);
+				},
+				.server => {
+					blockEntity.onUnloadServer(entityDataIndex);
+				},
+			}
+		}
+		self.blockPosToEntityDataMap.clearRetainingCapacity();
+	}
+
 	/// Updates a block if it is inside this chunk.
 	/// Does not do any bound checks. They are expected to be done with the `liesInChunk` function.
 	pub fn updateBlock(self: *Chunk, _x: i32, _y: i32, _z: i32, newBlock: Block) void {
diff --git a/src/renderer/chunk_meshing.zig b/src/renderer/chunk_meshing.zig
index c65b02bc..8fecfd0d 100644
--- a/src/renderer/chunk_meshing.zig
+++ b/src/renderer/chunk_meshing.zig
@@ -694,6 +694,7 @@ pub const ChunkMesh = struct { // MARK: ChunkMesh
 		chunkBuffer.free(self.chunkAllocation);
 		self.opaqueMesh.deinit();
 		self.transparentMesh.deinit();
+		self.chunk.unloadBlockEntities(.client);
 		self.chunk.deinit();
 		main.globalAllocator.free(self.currentSorting);
 		main.globalAllocator.free(self.sortingOutputBuffer);