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Merged
jobala merged 2 commits into from
Nov 6, 2025
Merged

Integrate wal #28

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7ae1920
integrate wal with memtable
jobala Nov 6, 2025
5a5d34c
recover memtable state from WAL
jobala Nov 6, 2025
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5 changes: 5 additions & 0 deletions storage/src/compaction/compact.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down Expand Up @@ -139,11 +140,13 @@ mod tests {
#[test]
fn scans_through_memtables_l0_l1_sstables() {
let db_dir = String::from(tempdir().unwrap().path().to_str().unwrap());

let config = Config {
sst_size: 4,
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down Expand Up @@ -206,6 +209,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);
let mut entries = get_entries();
Expand Down Expand Up @@ -262,6 +266,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down
23 changes: 18 additions & 5 deletions storage/src/compaction/flush.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
use anyhow::Result;
use std::{
fs,
path::Path,
sync::Arc,
thread::{self, JoinHandle},
time::Duration,
Expand All @@ -15,11 +17,11 @@ impl Storage {
let mut sst_builder = SSTableBuilder::new(self.config.block_size);
let mut guard = self.state.write().unwrap();

let mut memtables = guard.frozen_memtables.clone();
let mut frozen_memtables = guard.frozen_memtables.clone();
let mut l0_sstables = guard.l0_sstables.clone();
let mut sstables = guard.sstables.clone();

let Some(memtable) = memtables.pop() else {
let Some(memtable) = frozen_memtables.pop() else {
return Ok(());
};
memtable.flush(&mut sst_builder)?;
Expand All @@ -32,12 +34,16 @@ impl Storage {
l0_sstables.insert(0, memtable.id);
sstables.insert(memtable.id, Arc::new(sst));

if self.config.enable_wal {
self.remove_wal(memtable.id)?;
}

*guard = Arc::new(StorageState {
memtable: guard.memtable.clone(),
frozen_memtables: memtables,
levels: guard.levels.clone(),
frozen_memtables,
l0_sstables,
sstables,
levels: guard.levels.clone(),
memtable: guard.memtable.clone(),
});

memtable.id
Expand All @@ -61,6 +67,13 @@ impl Storage {
Ok(())
}

fn remove_wal(&self, id: usize) -> Result<()> {
let wal_path = Path::new(&self.config.db_dir).join(format!("{id}.wal"));
fs::remove_file(wal_path)?;

Ok(())
}

pub fn sst_path(&self, id: usize) -> String {
format!("{}/{}.sst", self.config.db_dir, id)
}
Expand Down
113 changes: 99 additions & 14 deletions storage/src/lsm_storage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,11 +48,14 @@ pub struct Config {
pub block_size: usize,
pub num_memtable_limit: usize,
pub db_dir: String,
pub enable_wal: bool,
}

pub fn new(config: Config) -> Arc<Storage> {
let state_lock = Mutex::new(());
let block_cache = Arc::new(BlockCache::new(4096));
let db_dir = Path::new(&config.db_dir);

create_db_dir(db_dir);

let manifest;
Expand All @@ -66,26 +69,74 @@ pub fn new(config: Config) -> Arc<Storage> {
Err(_) => manifest = Manifest::create(manifest_file).unwrap(),
}

let (l0_sst_ids, l1_sst_ids, sstables) =
let (memtable_ids, l0_sst_ids, l1_sst_ids, sstables) =
load_sstables(db_dir, block_cache, manifest_records).expect("loaded sstables");

let sst_id = match ([&l0_sst_ids[..], &l1_sst_ids[..]].concat()).iter().max() {
let sst_id = match ([&memtable_ids[..], &l0_sst_ids[..], &l1_sst_ids[..]].concat())
.iter()
.max()
{
Some(id) => id + 1,
None => 0,
};

let (memtable, frozen_memtables) = match config.enable_wal {
true => {
let wal_path = db_dir.join(format!("{sst_id}.wal"));
if memtable_ids.is_empty() {
let memtable = Memtable::new_with_wal(sst_id, wal_path.as_path()).expect("");
manifest
.add_record(
&state_lock.lock().unwrap(),
ManifestRecord::NewMemtable(sst_id),
)
.expect("added manifest record");

(Arc::new(memtable), vec![])
} else {
let mut memtables = vec![];
for id in memtable_ids {
let wal_path = db_dir.join(format!("{id}.wal"));
let memtable =
Memtable::new_with_wal(id, wal_path.as_path()).expect("created memtable");
memtables.push(Arc::new(memtable));
}

(memtables.remove(0), memtables)
}
}
_ => {
manifest
.add_record(
&state_lock.lock().unwrap(),
ManifestRecord::NewMemtable(sst_id),
)
.expect("added manifest record");

(Arc::new(Memtable::new(sst_id)), vec![])
}
};

if memtable.get_size() == 0 {
manifest
.add_record(
&state_lock.lock().unwrap(),
ManifestRecord::NewMemtable(sst_id),
)
.expect("added manifest record");
}

Arc::new(Storage {
config,
sst_id: AtomicUsize::new(sst_id),
state_lock: Mutex::new(()),
state_lock,
manifest,
sst_id: AtomicUsize::new(sst_id),
block_cache: Arc::new(BlockCache::new(1 << 20)), // 1mb cache
state: RwLock::new(Arc::new(StorageState {
l0_sstables: l0_sst_ids,
sstables,
frozen_memtables,
memtable,
l0_sstables: l0_sst_ids,
levels: vec![(0, l1_sst_ids)],
frozen_memtables: Vec::new(),
memtable: Arc::new(Memtable::new(sst_id)),
})),
})
}
Expand All @@ -100,7 +151,7 @@ impl Storage {
size = guard.memtable.get_size();
}

self.try_freeze(size);
self.try_freeze(size)?;
Ok(())
}

Expand Down Expand Up @@ -231,26 +282,32 @@ impl Storage {
Ok(LsmIterator::new(mem_l0_l1, map_bound(upper)))
}

fn try_freeze(&self, size: usize) {
fn try_freeze(&self, size: usize) -> Result<()> {
if size >= self.config.sst_size {
let lock = self.state_lock.lock().unwrap();
self.freeze(&lock);
self.freeze(&lock)?;
}

Ok(())
}

fn freeze(&self, _state_lock: &MutexGuard<()>) {
fn freeze(&self, state_lock: &MutexGuard<()>) -> Result<()> {
let mut guard = self.state.write().unwrap();
let memtable = guard.memtable.clone();
memtable.sync_wal()?;

// check again, another thread might have frozen the memtable already.
if memtable.get_size() >= self.config.sst_size {
let mut frozen_memtables = guard.frozen_memtables.clone();
frozen_memtables.insert(0, memtable);

let id = self.get_sst_id();
self.manifest
.add_record(state_lock, ManifestRecord::NewMemtable(id))?;
let memtable = self.create_memtable(id)?;

*guard = Arc::new(StorageState {
memtable: Arc::new(Memtable::new(id)),
memtable: Arc::new(memtable),
frozen_memtables,
l0_sstables: guard.l0_sstables.clone(),
sstables: guard.sstables.clone(),
Expand All @@ -259,12 +316,27 @@ impl Storage {

drop(guard);
}

Ok(())
}

fn create_memtable(&self, id: usize) -> Result<Memtable> {
let wal_path = Path::new(&self.config.db_dir).join(format!("{id}.wal"));
let memtable = match self.config.enable_wal {
true => Memtable::new_with_wal(id, wal_path.as_path()).expect("memtable with wal"),
_ => Memtable::new(id),
};

Ok(memtable)
}

pub(crate) fn get_sst_id(&self) -> usize {
self.sst_id.fetch_add(1, SeqCst);
self.sst_id.load(SeqCst)
}
pub fn sync(&self) -> Result<()> {
self.state.read().unwrap().memtable.sync_wal()
}
}

#[cfg(test)]
Expand All @@ -284,6 +356,7 @@ mod tests {
block_size: 32,
db_dir: String::from(tempdir().unwrap().path().to_str().unwrap()),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -303,6 +376,7 @@ mod tests {
block_size: 32,
db_dir: String::from(tempdir().unwrap().path().to_str().unwrap()),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -328,6 +402,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -345,6 +420,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};

let storage = new(config);
Expand All @@ -360,6 +436,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -376,6 +453,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};

let storage = new(config);
Expand All @@ -398,6 +476,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -422,6 +501,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};

let new_entries = vec![(b"a", b"20"), (b"e", b"21"), (b"d", b"22"), (b"b", b"23")];
Expand Down Expand Up @@ -472,6 +552,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand All @@ -496,6 +577,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};

let new_entries = vec![(b"a", b"20"), (b"e", b"21"), (b"d", b"22"), (b"b", b"23")];
Expand All @@ -516,7 +598,7 @@ mod tests {
while iter.is_valid() {
let k = from_utf8(iter.key()).unwrap();
let v = from_utf8(iter.value()).unwrap();

println!("key: {:?}, value: {:?}", k, v);
keys.push(String::from(k));
values.push(String::from(v));

Expand All @@ -535,6 +617,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down Expand Up @@ -593,6 +676,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down Expand Up @@ -623,6 +707,7 @@ mod tests {
block_size: 32,
db_dir: db_dir.clone(),
num_memtable_limit: 5,
enable_wal: true,
};
let storage = new(config);

Expand Down
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