finish 2.7

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-mvcc/src/table/bloom.rs

@@ -1,6 +1,7 @@
 // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0.
 
-use bytes::{BufMut, Bytes, BytesMut};
+use anyhow::{bail, Result};
+use bytes::{Buf, BufMut, Bytes, BytesMut};
 
 /// Implements a bloom filter
 pub struct Bloom {
@@ -45,19 +46,26 @@ impl<T: AsMut<[u8]>> BitSliceMut for T {
 
 impl Bloom {
     /// Decode a bloom filter
-    pub fn decode(buf: &[u8]) -> Self {
-        let filter = &buf[..buf.len() - 1];
-        let k = buf[buf.len() - 1];
-        Self {
+    pub fn decode(buf: &[u8]) -> Result<Self> {
+        let checksum = (&buf[buf.len() - 4..buf.len()]).get_u32();
+        if checksum != crc32fast::hash(&buf[..buf.len() - 4]) {
+            bail!("checksum mismatched for bloom filters");
+        }
+        let filter = &buf[..buf.len() - 5];
+        let k = buf[buf.len() - 5];
+        Ok(Self {
             filter: filter.to_vec().into(),
             k,
-        }
+        })
     }
 
     /// Encode a bloom filter
     pub fn encode(&self, buf: &mut Vec<u8>) {
+        let offset = buf.len();
         buf.extend(&self.filter);
         buf.put_u8(self.k);
+        let checksum = crc32fast::hash(&buf[offset..]);
+        buf.put_u32(checksum);
     }
 
     /// Get bloom filter bits per key from entries count and FPR