feat: Added on-disk cache for files, and way to lookup files. Also started on serialization

Cargo.lock

@@ -1104,18 +1104,18 @@ checksum = "a3f0bf26fd526d2a95683cd0f87bf103b8539e2ca1ef48ce002d67aad59aa0b4"
 
 [[package]]
 name = "serde"
-version = "1.0.188"
+version = "1.0.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf9e0fcba69a370eed61bcf2b728575f726b50b55cba78064753d708ddc7549e"
+checksum = "8e422a44e74ad4001bdc8eede9a4570ab52f71190e9c076d14369f38b9200537"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.188"
+version = "1.0.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4eca7ac642d82aa35b60049a6eccb4be6be75e599bd2e9adb5f875a737654af2"
+checksum = "1e48d1f918009ce3145511378cf68d613e3b3d9137d67272562080d68a2b32d5"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1190,6 +1190,8 @@ dependencies = [
  "clap",
  "parquet",
  "rand",
+ "serde",
+ "serde_json",
  "tokio",
 ]
 

Cargo.toml

@@ -11,4 +11,6 @@ axum = "0.6.20"
 clap = { version = "4.4.5", features = ["derive"] }
 parquet = "47.0.0"
 rand = "0.8.5"
+serde = { version = "1.0.189", features = ["derive"] }
+serde_json = "1.0.107"
 tokio = { version = "1.32.0", features = ["macros", "rt-multi-thread"] }

src/simple_server/server.rs

@@ -10,14 +10,14 @@ struct MultipleBlocks {
 #[derive(Debug)]
 pub struct SimpleServer {
     chunks: Vec<ChunkData>,
-    block_ranges: Vec<MultipleBlocks>,
+    // block_ranges: Vec<MultipleBlocks>,
 }
 
 impl SimpleServer {
     pub fn new() -> Self {
         SimpleServer {
             chunks: Vec::new(),
-            block_ranges: Vec::new(),
+            // block_ranges: Vec::new(),
         }
     }
 
@@ -78,13 +78,14 @@ impl StorageServer for SimpleServer {
     }
 
     fn change_block_range(&mut self, target_stage: BlockID, start: &BlockPos, end: &BlockPos) {
-        self.block_ranges.push(MultipleBlocks {
-            id: target_stage,
-            range: BlockRange {
-                start: start.clone(),
-                end: end.clone(),
-            },
-        })
+        unimplemented!()
+        // self.block_ranges.push(MultipleBlocks {
+        //     id: target_stage,
+        //     range: BlockRange {
+        //         start: start.clone(),
+        //         end: end.clone(),
+        //     },
+        // })
     }
 
     fn read_block_at(&self, pos: &BlockPos) -> BlockID {
@@ -96,11 +97,11 @@ impl StorageServer for SimpleServer {
             return chunk_section.get_block_at_index(pos).clone();
         }
 
-        for blocks in self.block_ranges.iter() {
-            if blocks.range.within_range(&pos) {
-                return blocks.id.clone();
-            }
-        }
+        // for blocks in self.block_ranges.iter() {
+        //     if blocks.range.within_range(&pos) {
+        //         return blocks.id.clone();
+        //     }
+        // }
 
         BlockID::Empty
     }

src/storage/chunk_compression.rs

@@ -0,0 +1,2 @@
+
+

src/storage/disk_storage.rs

@@ -1,19 +1,81 @@
 use super::world::{BlockID, ChunkData, ChunkPos};
-use std::fs::File;
+use std::cmp::Ordering;
+use std::{collections::HashMap, fs::File, time::Instant};
 
 const DATABASE_FILE_LOCATION: &str = "./persistence";
 
-struct RunLengthEncoding {
-    pairs: Vec<(usize, BlockID)>,
+struct ChunkFile {}
+
+const CACHED_CHUNK_FILES: usize = 1;
+
+/// `ChunkStorageCache` caches a list of the most recently used file handles
+/// where chunks are stored from, and allows for faster accessing of the data
+/// from chunks
+struct ChunkStorageCache {
+    // `cached_chunk_files` is a vector of cached file handles that are already open
+    cached_chunk_files: [File; CACHED_CHUNK_FILES],
+    // `cached_file_names` is a list of all the filenames that are contained
+    // within the cache
+    cached_file_names: HashMap<String, usize>,
+    last_used_times: [Instant; CACHED_CHUNK_FILES],
 }
 
-impl RunLengthEncoding {
-    fn from_chunk(chunk_data: &ChunkData) -> Self {
-        for section in chunk_data.sections {
-            for index in section.chunk_data {
-                // Yes
-            }
-        }
+impl ChunkStorageCache {
+    fn load_chunk_file(&mut self, file_name: &str) -> &File {
+        let chunk_file = File::open(file_name).expect("Opening file for chunk failed");
+
+        // Add the newly opened file to the cache
+
+        // Insert the new item to replace the item that was last accessed
+        // The minimum time should be the oldest time
+        let (last_used_index, _) = self
+            .last_used_times
+            .iter()
+            .enumerate()
+            .reduce(
+                |(fst_index, fst_time), (snd_index, snd_time)| match fst_time.cmp(&snd_time) {
+                    Ordering::Less => (fst_index, fst_time),
+                    Ordering::Equal | Ordering::Greater => (snd_index, snd_time),
+                },
+            )
+            .expect("There should always be a last used index");
+
+        // Next, we have to:
+        // * Remove the old filename and index mapping from the names
+        // * Replace the last used time with the curent time
+        // * Replace the open file with the current one
+
+        // Find the name of the previous entry
+        let (previous_file_name, _) = self
+            .cached_file_names
+            .iter()
+            .find(|(_, &array_index)| array_index == last_used_index)
+            .expect("The last used index should always have a name");
+
+        self.cached_file_names.remove(&previous_file_name.clone());
+        self.cached_file_names
+            .insert(file_name.to_string(), last_used_index);
+        // Replace the timestamp with the new timestamp
+        self.last_used_times[last_used_index] = Instant::now();
+        self.cached_chunk_files[last_used_index] = chunk_file;
+
+        &self.cached_chunk_files[last_used_index]
+    }
+    /// `fetch_chunk_by_pos` takes in the position of a chunk, and returns the
+    /// data of the chunk from disk
+    ///
+    /// This operation is cached, if possible, so that subsequent accesses to
+    /// the same chunk are handled by the same file
+    pub fn fetch_chunk_by_pos(&mut self, pos: &ChunkPos) -> ChunkData {
+        let file_name = pos.storage_file_name();
+
+        let file_index = self.cached_file_names.get(file_name.as_str());
+
+        let chunk_file = match file_index {
+            Some(index) => &self.cached_chunk_files[*index],
+            None => self.load_chunk_file(file_name.as_str()),
+        };
+
+        panic!("Yes");
     }
 }
-

src/storage/mod.rs

@@ -1,2 +1,3 @@
-// mod disk_storage;
+mod chunk_compression;
+mod disk_storage;
 pub mod world;

src/storage/world.rs

@@ -1,13 +1,16 @@
 use core::fmt;
+use serde::ser;
+use serde::Serialize;
 use std::{
     cmp::{max, min},
     fmt::Debug,
+    fs::File,
 };
 
 const SECTIONS_PER_CHUNK: usize = 16;
 const SLICE_SIZE: usize = 16 * 16;
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Serialize)]
 pub struct ChunkPos {
     pub x: isize,
     pub z: isize,
@@ -22,7 +25,13 @@ impl From<&BlockPos> for ChunkPos {
     }
 }
 
-#[derive(Debug)]
+impl ChunkPos {
+    pub fn storage_file_name(&self) -> String {
+        format!("{}.{}.chunk", self.x, self.z)
+    }
+}
+
+#[derive(Debug, Serialize)]
 pub struct ChunkData {
     pub pos: ChunkPos,
     pub sections: [ChunkSection; SECTIONS_PER_CHUNK],
@@ -39,6 +48,14 @@ impl ChunkData {
     pub fn section_for(&self, block_pos: &BlockPos) -> &ChunkSection {
         &self.sections[block_pos.y % 16]
     }
+
+    pub fn write_to_file(&self, output_file: &mut File) {
+        let serialized = serde_json::to_string(self).unwrap();
+    }
+
+    pub fn read_from_file(chunk_file: &File) -> Self {
+        unimplemented!()
+    }
 }
 
 // https://wiki.vg/Chunk_Format
@@ -168,7 +185,7 @@ impl BlockRange {
 
 /// BlockID represents the type of block stored
 #[repr(u8)]
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq, Serialize)]
 pub enum BlockID {
     Empty,
     Generic,