From 8e467d5447d5fdcd19e7589d7b3a56fde5b78414 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E3=83=AA=E3=82=AD=E8=90=8C?= <commits@liquidev.net>
Date: Fri, 5 Sep 2025 20:20:45 +0200
Subject: [PATCH] fix chunk images not being populated when the first client
 joins the room

---
 crates/rkgk/src/api/wall.rs          | 12 +++++++----
 crates/rkgk/src/wall/broker.rs       |  8 ++++++-
 crates/rkgk/src/wall/chunk_images.rs | 32 ++++++++++++++++++----------
 3 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/crates/rkgk/src/api/wall.rs b/crates/rkgk/src/api/wall.rs
index d069911..16f88b2 100644
--- a/crates/rkgk/src/api/wall.rs
+++ b/crates/rkgk/src/api/wall.rs
@@ -25,7 +25,7 @@ use tokio::{
     select,
     sync::{mpsc, oneshot},
 };
-use tracing::{error, info, info_span, instrument};
+use tracing::{debug, error, info, info_span, instrument};
 
 use crate::{
     login::{self, database::LoginStatus},
@@ -370,6 +370,7 @@ impl SessionLoop {
                 top_left,
                 bottom_right,
             } => {
+                debug!(?top_left, ?bottom_right, "Request::Viewport");
                 self.viewport_chunks = ChunkIterator::new(top_left, bottom_right);
                 self.send_chunks(ws).await?;
             }
@@ -391,11 +392,12 @@ impl SessionLoop {
 
             // Number of chunks iterated is limited per packet, so as not to let the client
             // stall the server by sending in a huge viewport.
+            debug!(?self.viewport_chunks, ?self.sent_chunks);
             for _ in 0..9000 {
                 if let Some(position) = self.viewport_chunks.next() {
-                    if !self.sent_chunks.insert(position)
-                        || !self.chunk_images.chunk_exists(position)
-                    {
+                    let sent = !self.sent_chunks.insert(position);
+                    if sent || !self.chunk_images.chunk_exists(position) {
+                        debug!(?position, "skipping chunk");
                         continue;
                     }
                     positions.push(position);
@@ -404,6 +406,8 @@ impl SessionLoop {
                 }
             }
 
+            debug!(num = positions.len(), "pending chunk images");
+
             self.pending_images
                 .extend(self.chunk_images.encoded(positions).await.data);
         }
diff --git a/crates/rkgk/src/wall/broker.rs b/crates/rkgk/src/wall/broker.rs
index 96bfe8f..46ad53d 100644
--- a/crates/rkgk/src/wall/broker.rs
+++ b/crates/rkgk/src/wall/broker.rs
@@ -68,7 +68,13 @@ impl Broker {
                     default_wall_settings: self.settings.default_wall_settings,
                 })?);
                 let wall = Arc::new(Wall::new(*db.wall_settings()));
-                let chunk_images = Arc::new(ChunkImages::new(Arc::clone(&wall), Arc::clone(&db)));
+                let chunk_images = Arc::new(ChunkImages::new(
+                    Arc::clone(&wall),
+                    Arc::clone(&db),
+                    // NOTE: Upon initial loading, this will stall until the query finishes.
+                    // This is probably very sub-optimal on walls with a lot of chunks.
+                    ChunkImages::populate(&db).await,
+                ));
                 let auto_save = Arc::new(AutoSave::new(
                     Arc::clone(&wall),
                     Arc::clone(&chunk_images),
diff --git a/crates/rkgk/src/wall/chunk_images.rs b/crates/rkgk/src/wall/chunk_images.rs
index 0e73d9b..7b6f31d 100644
--- a/crates/rkgk/src/wall/chunk_images.rs
+++ b/crates/rkgk/src/wall/chunk_images.rs
@@ -5,10 +5,16 @@ use eyre::Context;
 use rayon::iter::{IntoParallelIterator, IntoParallelRefIterator, ParallelIterator};
 use tiny_skia::{IntSize, Pixmap};
 use tokio::sync::{mpsc, oneshot, Mutex};
-use tracing::{error, info, instrument};
+use tracing::{debug, error, info, instrument};
 
 use super::{database::ChunkDataPair, Chunk, ChunkPosition, Database, Wall};
 
+/// Initial population of `ChunkImages`'s cache.
+/// Created as part of an async process before `new`.
+pub struct Population {
+    chunks_in_db: DashSet<ChunkPosition>,
+}
+
 /// Chunk image encoding, caching, and storage service.
 pub struct ChunkImages {
     wall: Arc<Wall>,
@@ -48,13 +54,13 @@ enum Command {
 }
 
 impl ChunkImages {
-    pub fn new(wall: Arc<Wall>, db: Arc<Database>) -> Self {
+    pub fn new(wall: Arc<Wall>, db: Arc<Database>, population: Population) -> Self {
         let (commands_tx, commands_rx) = mpsc::channel(32);
 
         let async_loop = Arc::new(ChunkImageLoop {
             wall: Arc::clone(&wall),
             db,
-            chunks_in_db: DashSet::new(),
+            chunks_in_db: population.chunks_in_db,
         });
         tokio::spawn(Arc::clone(&async_loop).enter(commands_rx));
 
@@ -65,6 +71,17 @@ impl ChunkImages {
         }
     }
 
+    pub async fn populate(db: &Database) -> Population {
+        Population {
+            chunks_in_db: db
+                .get_all_chunks()
+                .await
+                .expect("could not list chunks in the database")
+                .into_iter()
+                .collect(),
+        }
+    }
+
     pub async fn encoded(&self, chunks: Vec<ChunkPosition>) -> EncodeResult {
         let (tx, rx) = oneshot::channel();
         _ = self
@@ -233,14 +250,7 @@ impl ChunkImageLoop {
     }
 
     async fn enter(self: Arc<Self>, mut commands_rx: mpsc::Receiver<Command>) {
-        let all_chunks = self
-            .db
-            .get_all_chunks()
-            .await
-            .expect("could not list chunks in the database");
-        for position in all_chunks {
-            self.chunks_in_db.insert(position);
-        }
+        debug!(num = ?self.chunks_in_db.len(), "chunks in database");
 
         while let Some(command) = commands_rx.recv().await {
             match command {