From d4fd07400008247c475ffe2c66bb2bd57bf7ab5c Mon Sep 17 00:00:00 2001
From: Trinity Pointard <trinity.pointard@gmail.com>
Date: Wed, 7 Apr 2021 02:13:26 +0200
Subject: [PATCH] use zstd checksumming

---
 src/model/block.rs | 66 ++++++++++++++++++++++++++--------------------
 src/util/config.rs |  2 +-
 2 files changed, 38 insertions(+), 30 deletions(-)

diff --git a/src/model/block.rs b/src/model/block.rs
index 090ffbc2..699ff32d 100644
--- a/src/model/block.rs
+++ b/src/model/block.rs
@@ -9,7 +9,7 @@ use serde::{Deserialize, Serialize};
 use tokio::fs;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::sync::{watch, Mutex, Notify};
-use zstd::stream::{decode_all as zstd_decode, encode_all as zstd_encode};
+use zstd::stream::{decode_all as zstd_decode, Encoder};
 
 use garage_util::data::*;
 use garage_util::error::Error;
@@ -43,7 +43,10 @@ pub enum Message {
 	GetBlock(Hash),
 	/// Message to send a block of data, either because requested, of for first delivery of new
 	/// block
-	PutBlock { hash: Hash, data: BlockData },
+	PutBlock {
+		hash: Hash,
+		data: BlockData,
+	},
 	/// Ask other node if they should have this block, but don't actually have it
 	NeedBlockQuery(Hash),
 	/// Response : whether the node do require that block
@@ -64,6 +67,13 @@ impl BlockData {
 			BlockData::Compressed(_) => true,
 		}
 	}
+
+	pub fn buffer(&self) -> &Vec<u8> {
+		match self {
+			BlockData::Plain(b) => b,
+			BlockData::Compressed(b) => b,
+		}
+	}
 }
 
 impl RpcMessage for Message {}
@@ -164,6 +174,10 @@ impl BlockManager {
 
 	/// Write a block to disk
 	pub async fn write_block(&self, hash: &Hash, data: &BlockData) -> Result<Message, Error> {
+		let mut path = self.block_dir(hash);
+
+		let _lock = self.data_dir_lock.lock().await;
+
 		let clean_plain = match self.is_block_compressed(hash).await {
 			Ok(true) => return Ok(Message::Ok),
 			Ok(false) if !data.is_compressed() => return Ok(Message::Ok), // we have a plain block, and the provided block is not compressed either
@@ -171,29 +185,17 @@ impl BlockManager {
 			Err(_) => false,
 		};
 
-		let mut path = self.block_dir(hash);
-
-		let (buffer, checksum) = match data {
-			BlockData::Plain(b) => (b, None),
-			BlockData::Compressed(b) => {
-				let checksum = blake2sum(&b);
-				(b, Some(checksum))
-			}
-		};
-
-		let _lock = self.data_dir_lock.lock().await;
-
 		fs::create_dir_all(&path).await?;
 		path.push(hex::encode(hash));
-		if checksum.is_some() {
-			path.set_extension("zst_b2");
+
+		if data.is_compressed() {
+			path.set_extension("zst");
 		}
 
+		let buffer = data.buffer();
+
 		let mut f = fs::File::create(path.clone()).await?;
 		f.write_all(&buffer).await?;
-		if let Some(checksum) = checksum {
-			f.write_all(checksum.as_slice()).await?;
-		}
 
 		if clean_plain {
 			path.set_extension("");
@@ -215,7 +217,7 @@ impl BlockManager {
 				f.map(|f| (f, false)).map_err(Into::into)
 			}
 			Ok(true) => {
-				path.set_extension("zst_b2");
+				path.set_extension("zst");
 				let f = fs::File::open(&path).await;
 				f.map(|f| (f, true)).map_err(Into::into)
 			}
@@ -233,14 +235,7 @@ impl BlockManager {
 		drop(f);
 
 		let sum_ok = if compressed {
-			if data.len() >= 32 {
-				let data_len = data.len() - 32;
-				let checksum = data.split_off(data_len);
-				blake2sum(&data[..]).as_slice() == &checksum
-			} else {
-				// the file is too short to be valid
-				false
-			}
+			zstd_check_checksum(&data[..])
 		} else {
 			blake2sum(&data[..]) == *hash
 		};
@@ -287,7 +282,7 @@ impl BlockManager {
 
 	async fn is_block_compressed(&self, hash: &Hash) -> Result<bool, Error> {
 		let mut path = self.block_path(hash);
-		path.set_extension("zst_b2");
+		path.set_extension("zst");
 		if fs::metadata(&path).await.is_ok() {
 			return Ok(true);
 		}
@@ -634,3 +629,16 @@ fn u64_from_be_bytes<T: AsRef<[u8]>>(bytes: T) -> u64 {
 	x8.copy_from_slice(bytes.as_ref());
 	u64::from_be_bytes(x8)
 }
+
+fn zstd_check_checksum<R: std::io::Read>(source: R) -> bool {
+	zstd::stream::copy_decode(source, std::io::sink()).is_ok()
+}
+
+fn zstd_encode<R: std::io::Read>(mut source: R, level: i32) -> std::io::Result<Vec<u8>> {
+	let mut result = Vec::<u8>::new();
+	let mut encoder = Encoder::new(&mut result, level)?;
+	encoder.include_checksum(true)?;
+	std::io::copy(&mut source, &mut encoder)?;
+	encoder.finish()?;
+	Ok(result)
+}
diff --git a/src/util/config.rs b/src/util/config.rs
index ab9cae6c..29901d46 100644
--- a/src/util/config.rs
+++ b/src/util/config.rs
@@ -45,7 +45,7 @@ pub struct Config {
 	#[serde(default = "default_replication_factor")]
 	pub data_replication_factor: usize,
 
-    /// Zstd compression level used on data blocks
+	/// Zstd compression level used on data blocks
 	#[serde(default)]
 	pub compression_level: i32,