fix compile error

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

mini-lsm-mvcc/src/lsm_storage.rs

@@ -302,6 +302,8 @@ impl LsmStorageInner {
         self.manifest.as_ref().unwrap()
     }
 
+    /// Start the storage engine by either loading an existing directory or creating a new one if the directory does
+    /// not exist.
     /// Start the storage engine by either loading an existing directory or creating a new one if the directory does
     /// not exist.
     pub(crate) fn open(path: impl AsRef<Path>, options: LsmStorageOptions) -> Result<Self> {
@@ -328,6 +330,7 @@ impl LsmStorageInner {
             std::fs::create_dir_all(path).context("failed to create DB dir")?;
         }
         let manifest_path = path.join("MANIFEST");
+        let mut last_commit_ts = 0;
         if !manifest_path.exists() {
             if options.enable_wal {
                 state.memtable = Arc::new(MemTable::create_with_wal(
@@ -381,6 +384,7 @@ impl LsmStorageInner {
                     FileObject::open(&Self::path_of_sst_static(path, table_id))
                         .context("failed to open SST")?,
                 )?;
+                last_commit_ts = last_commit_ts.max(sst.max_ts());
                 state.sstables.insert(table_id, Arc::new(sst));
                 sst_cnt += 1;
             }
@@ -394,6 +398,13 @@ impl LsmStorageInner {
                 for id in memtables.iter() {
                     let memtable =
                         MemTable::recover_from_wal(*id, Self::path_of_wal_static(path, *id))?;
+                    let max_ts = memtable
+                        .map
+                        .iter()
+                        .map(|x| x.key().ts())
+                        .max()
+                        .unwrap_or_default();
+                    last_commit_ts = last_commit_ts.max(max_ts);
                     if !memtable.is_empty() {
                         state.imm_memtables.insert(0, Arc::new(memtable));
                         wal_cnt += 1;
@@ -421,7 +432,7 @@ impl LsmStorageInner {
             compaction_controller,
             manifest: Some(manifest),
             options: options.into(),
-            mvcc: Some(LsmMvccInner::new(0)),
+            mvcc: Some(LsmMvccInner::new(last_commit_ts)),
         };
         storage.sync_dir()?;
 

mini-lsm-mvcc/src/mem_table.rs

@@ -19,7 +19,7 @@ use crate::wal::Wal;
 /// An initial implementation of memtable is part of week 1, day 1. It will be incrementally implemented in other
 /// chapters of week 1 and week 2.
 pub struct MemTable {
-    map: Arc<SkipMap<KeyBytes, Bytes>>,
+    pub(crate) map: Arc<SkipMap<KeyBytes, Bytes>>,
     wal: Option<Wal>,
     id: usize,
     approximate_size: Arc<AtomicUsize>,

mini-lsm-mvcc/src/table.rs

@@ -29,8 +29,8 @@ pub struct BlockMeta {
 
 impl BlockMeta {
     /// Encode block meta to a buffer.
-    pub fn encode_block_meta(block_meta: &[BlockMeta], buf: &mut Vec<u8>) {
+    pub fn encode_block_meta(block_meta: &[BlockMeta], max_ts: u64, buf: &mut Vec<u8>) {
-        let mut estimated_size = std::mem::size_of::<u32>();
+        let mut estimated_size = std::mem::size_of::<u32>(); // number of blocks
         for meta in block_meta {
             // The size of offset
             estimated_size += std::mem::size_of::<u32>();
@@ -43,7 +43,9 @@ impl BlockMeta {
             // The size of actual key
             estimated_size += meta.last_key.raw_len();
         }
-        estimated_size += std::mem::size_of::<u32>();
+        estimated_size += std::mem::size_of::<u64>(); // max timestamp
+        estimated_size += std::mem::size_of::<u32>(); // checksum
+
         // Reserve the space to improve performance, especially when the size of incoming data is
         // large
         buf.reserve(estimated_size);
@@ -58,12 +60,13 @@ impl BlockMeta {
             buf.put_slice(meta.last_key.key_ref());
             buf.put_u64(meta.last_key.ts());
         }
+        buf.put_u64(max_ts);
         buf.put_u32(crc32fast::hash(&buf[original_len + 4..]));
         assert_eq!(estimated_size, buf.len() - original_len);
     }
 
     /// Decode block meta from a buffer.
-    pub fn decode_block_meta(mut buf: &[u8]) -> Result<Vec<BlockMeta>> {
+    pub fn decode_block_meta(mut buf: &[u8]) -> Result<(Vec<BlockMeta>, u64)> {
         let mut block_meta = Vec::new();
         let num = buf.get_u32() as usize;
         let checksum = crc32fast::hash(&buf[..buf.remaining() - 4]);
@@ -81,11 +84,12 @@ impl BlockMeta {
                 last_key,
             });
         }
+        let max_ts = buf.get_u64();
         if buf.get_u32() != checksum {
             bail!("meta checksum mismatched");
         }
 
-        Ok(block_meta)
+        Ok((block_meta, max_ts))
     }
 }
 
@@ -137,6 +141,7 @@ pub struct SsTable {
     first_key: KeyBytes,
     last_key: KeyBytes,
     pub(crate) bloom: Option<Bloom>,
+    max_ts: u64,
 }
 impl SsTable {
     #[cfg(test)]
@@ -154,7 +159,7 @@ impl SsTable {
         let raw_meta_offset = file.read(bloom_offset - 4, 4)?;
         let block_meta_offset = (&raw_meta_offset[..]).get_u32() as u64;
         let raw_meta = file.read(block_meta_offset, bloom_offset - 4 - block_meta_offset)?;
-        let block_meta = BlockMeta::decode_block_meta(&raw_meta[..])?;
+        let (block_meta, max_ts) = BlockMeta::decode_block_meta(&raw_meta[..])?;
         Ok(Self {
             file,
             first_key: block_meta.first().unwrap().first_key.clone(),
@@ -164,6 +169,7 @@ impl SsTable {
             id,
             block_cache,
             bloom: Some(bloom_filter),
+            max_ts,
         })
     }
 
@@ -183,6 +189,7 @@ impl SsTable {
             first_key,
             last_key,
             bloom: None,
+            max_ts: 0,
         }
     }
 
@@ -246,8 +253,6 @@ impl SsTable {
     }
 
     pub fn max_ts(&self) -> u64 {
-        // TODO(you): implement me
+        self.max_ts
-        // self.max_ts
-        0
     }
 }

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

@@ -19,6 +19,7 @@ pub struct SsTableBuilder {
     pub(crate) meta: Vec<BlockMeta>,
     block_size: usize,
     key_hashes: Vec<u32>,
+    max_ts: u64,
 }
 
 impl SsTableBuilder {
@@ -32,6 +33,7 @@ impl SsTableBuilder {
             block_size,
             builder: BlockBuilder::new(block_size),
             key_hashes: Vec::new(),
+            max_ts: 0,
         }
     }
 
@@ -41,6 +43,9 @@ impl SsTableBuilder {
             self.first_key.set_from_slice(key);
         }
 
+        if key.ts() > self.max_ts {
+            self.max_ts = key.ts();
+        }
         self.key_hashes.push(farmhash::fingerprint32(key.key_ref()));
 
         if self.builder.add(key, value) {
@@ -85,7 +90,7 @@ impl SsTableBuilder {
         self.finish_block();
         let mut buf = self.data;
         let meta_offset = buf.len();
-        BlockMeta::encode_block_meta(&self.meta, &mut buf);
+        BlockMeta::encode_block_meta(&self.meta, self.max_ts, &mut buf);
         buf.put_u32(meta_offset as u32);
         let bloom = Bloom::build_from_key_hashes(
             &self.key_hashes,
@@ -104,6 +109,7 @@ impl SsTableBuilder {
             block_meta_offset: meta_offset,
             block_cache,
             bloom: Some(bloom),
+            max_ts: self.max_ts,
         })
     }
 

mini-lsm-mvcc/src/tests.rs

@@ -10,8 +10,8 @@ mod week2_day1;
 mod week2_day2;
 mod week2_day3;
 mod week2_day4;
-// mod week2_day5;
+mod week2_day5;
-// mod week2_day6;
+mod week2_day6;
 mod week3_day1;
 mod week3_day2;
 mod week3_day3;

mini-lsm/src/table/builder.rs

@@ -104,6 +104,7 @@ impl SsTableBuilder {
             block_meta_offset: meta_offset,
             block_cache,
             bloom: Some(bloom),
+            max_ts: 0, // will be changed to latest ts in week 2
         })
     }