Added chunk data versioning system

server/src/terrain_persistence.rs

@@ -4,9 +4,10 @@ use common::{
     vol::RectRasterableVol,
 };
 use vek::*;
-use tracing::{info, error};
+use tracing::{info, error, warn};
 use serde::{Serialize, Deserialize};
 use std::{
+    io::{self, Read as _, Write as _},
     fs::File,
     path::PathBuf,
 };
@@ -33,29 +34,57 @@ impl Default for TerrainPersistence {
 }
 
 impl TerrainPersistence {
-    fn path_for(&self, key: Vec2<i32>) -> PathBuf {
+    fn path_for(&self, key: Vec2<i32>, ext: &str) -> PathBuf {
         let mut path = self.path.clone();
-        path.push(format!("chunk_{}_{}.dat", key.x, key.y));
+        path.push(format!("chunk_{}_{}.{}", key.x, key.y, ext));
         path
     }
 
     pub fn load_chunk(&mut self, key: Vec2<i32>) -> &mut Chunk {
-        let path = self.path_for(key);
+        let path = self.path_for(key, "dat");
+        let backup_path = self.path_for(key, "dat.backup");
         self.chunks
             .entry(key)
             .or_insert_with(|| {
-                File::open(path)
+                File::open(&path)
                     .ok()
-                    .and_then(|f| bincode::deserialize_from(&f).ok())
+                    .map(|f| {
+                        let bytes = match std::io::BufReader::new(f).bytes().collect::<Result<Vec<_>, _>>() {
+                            Ok(bytes) => bytes,
+                            Err(err) => {
+                                error!("Failed to load chunk {:?} from disk: {:?}", key, err);
+                                return Chunk::default();
+                            },
+                        };
+                        match Chunk::deserialize_from(std::io::Cursor::new(bytes)) {
+                            Some(chunk) => chunk,
+                            None => {
+                                error!("Failed to load chunk {:?}, moving to {:?} instead", key, backup_path);
+                                if let Err(err) = std::fs::copy(&path, backup_path)
+                                    .and_then(|_| std::fs::remove_file(&path))
+                                {
+                                    error!("{:?}", err);
+                                }
+                                Chunk::default()
+                            },
+                        }
+                    })
                     .unwrap_or_else(|| Chunk::default())
             })
     }
 
     pub fn unload_chunk(&mut self, key: Vec2<i32>) {
         if let Some(chunk) = self.chunks.remove(&key) {
-            if chunk.blocks.len() > 0 {
-                match File::create(self.path_for(key)) {
-                    Ok(file) => { bincode::serialize_into(file, &chunk); },
+            if chunk.blocks.len() > 0 { // No need to write if no blocks have ever been written
+                match File::create(self.path_for(key, "dat")) {
+                    Ok(file) => {
+                        let mut writer = std::io::BufWriter::new(file);
+                        if let Err(err) = bincode::serialize_into::<_, version::Current>(&mut writer, &chunk.prepare())
+                            .and_then(|_| Ok(writer.flush()?))
+                        {
+                            error!("Failed to write chunk to disk: {:?}", err);
+                        }
+                    },
                     Err(err) => error!("Failed to create file: {:?}", err),
                 }
             }
@@ -80,7 +109,80 @@ pub struct Chunk {
 }
 
 impl Chunk {
+    pub fn deserialize_from<R: io::Read + Clone>(reader: R) -> Option<Self> {
+        // Attempt deserialization through various versions
+        if let Ok(data) = bincode::deserialize_from::<_, version::V2>(reader.clone())
+            .map_err(|err| { warn!("Error when loading V2: {:?}", err); err })
+        {
+            Some(Chunk::from(data))
+        } else if let Ok(data) = bincode::deserialize_from::<_, Chunk>(reader.clone())
+            .map_err(|err| { warn!("Error when loading V1: {:?}", err); err })
+        {
+            Some(Chunk::from(data))
+        } else {
+            None
+        }
+    }
+
+    fn prepare(self) -> version::Current { self.into() }
+
     pub fn blocks(&self) -> impl Iterator<Item=(Vec3<i32>, Block)> + '_ {
         self.blocks.iter().map(|(k, b)| (*k, *b))
     }
 }
+
+mod version {
+    pub type Current = V2;
+
+    fn version_magic(n: u16) -> u64 {
+        (n as u64) | (0x3352ACEEA789 << 16)
+    }
+
+    use super::*;
+
+    // Convert back to current
+
+    impl From<Chunk> for Current {
+        fn from(chunk: Chunk) -> Self {
+            Self { version: version_magic(2), blocks: chunk.blocks
+                .into_iter()
+                .map(|(pos, b)| (pos.x as u8, pos.y as u8, pos.z as i16, b))
+                .collect() }
+        }
+    }
+
+    // V1
+
+    #[derive(Serialize, Deserialize)]
+    pub struct V1 {
+        pub blocks: HashMap<Vec3<i32>, Block>,
+    }
+
+    impl From<V1> for Chunk {
+        fn from(v1: V1) -> Self { Self { blocks: v1.blocks } }
+    }
+
+    // V2
+
+    #[derive(Serialize, Deserialize)]
+    pub struct V2 {
+        #[serde(deserialize_with = "version::<_, 2>")]
+        pub version: u64,
+        pub blocks: Vec<(u8, u8, i16, Block)>,
+    }
+
+    fn version<'de, D: serde::Deserializer<'de>, const V: u16>(de: D) -> Result<u64, D::Error> {
+        u64::deserialize(de).and_then(|x| if x == version_magic(V) {
+            Ok(x)
+        } else {
+            Err(serde::de::Error::invalid_value(serde::de::Unexpected::Unsigned(x), &"correct version"))
+        })
+    }
+
+    impl From<V2> for Chunk {
+        fn from(v2: V2) -> Self { Self { blocks: v2.blocks
+            .into_iter()
+            .map(|(x, y, z, b)| (Vec3::new(x as i32, y as i32, z as i32), b))
+            .collect() } }
+    }
+}