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patch memtable and add ts for wal

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Signed-off-by: Alex Chi <iskyzh@gmail.com>
This commit is contained in:
Alex Chi
2024-01-25 23:09:16 +08:00
parent 89acc23208
commit 218c73f384
11 changed files with 256 additions and 96 deletions
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4
mini-lsm-mvcc/src/key.rs
View File

@@ -94,6 +94,10 @@ impl Key<Vec<u8>> {
}
impl Key<Bytes> {
pub fn new() -> Self {
Self(Bytes::new(), TS_DEFAULT)
}
pub fn as_key_slice(&self) -> KeySlice {
Key(&self.0, self.1)
}

42
mini-lsm-mvcc/src/lsm_iterator.rs
View File

@@ -20,16 +20,24 @@ pub struct LsmIterator {
inner: LsmIteratorInner,
end_bound: Bound<Bytes>,
is_valid: bool,
read_ts: u64,
prev_key: Vec<u8>,
}
impl LsmIterator {
pub(crate) fn new(iter: LsmIteratorInner, end_bound: Bound<Bytes>) -> Result<Self> {
pub(crate) fn new(
iter: LsmIteratorInner,
end_bound: Bound<Bytes>,
read_ts: u64,
) -> Result<Self> {
let mut iter = Self {
is_valid: iter.is_valid(),
inner: iter,
end_bound,
read_ts,
prev_key: Vec::new(),
};
iter.move_to_non_delete()?;
iter.move_to_key()?;
Ok(iter)
}
@@ -47,9 +55,31 @@ impl LsmIterator {
Ok(())
}
fn move_to_non_delete(&mut self) -> Result<()> {
while self.is_valid() && self.inner.value().is_empty() {
self.next_inner()?;
fn move_to_key(&mut self) -> Result<()> {
loop {
while self.inner.is_valid() && self.inner.key().key_ref() == self.prev_key {
self.next_inner()?;
}
if !self.inner.is_valid() {
break;
}
self.prev_key.clear();
self.prev_key.extend(self.inner.key().key_ref());
while self.inner.is_valid()
&& self.inner.key().key_ref() == self.prev_key
&& self.inner.key().ts() > self.read_ts
{
self.next_inner()?;
}
if !self.inner.is_valid() {
break;
}
if self.inner.key().key_ref() != self.prev_key {
continue;
}
if !self.inner.value().is_empty() {
break;
}
}
Ok(())
}
@@ -72,7 +102,7 @@ impl StorageIterator for LsmIterator {
fn next(&mut self) -> Result<()> {
self.next_inner()?;
self.move_to_non_delete()?;
self.move_to_key()?;
Ok(())
}

75
mini-lsm-mvcc/src/lsm_storage.rs
View File

@@ -2,7 +2,7 @@ use std::collections::{BTreeSet, HashMap};
use std::fs::File;
use std::ops::Bound;
use std::path::{Path, PathBuf};
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
use std::sync::Arc;
use anyhow::{Context, Result};
@@ -21,7 +21,7 @@ use crate::iterators::StorageIterator;
use crate::key::{self, KeySlice};
use crate::lsm_iterator::{FusedIterator, LsmIterator};
use crate::manifest::{Manifest, ManifestRecord};
use crate::mem_table::{map_bound, MemTable};
use crate::mem_table::{map_bound, map_key_bound_plus_ts, MemTable};
use crate::table::{FileObject, SsTable, SsTableBuilder, SsTableIterator};
pub type BlockCache = moka::sync::Cache<(usize, usize), Arc<Block>>;
@@ -152,6 +152,8 @@ pub(crate) struct LsmStorageInner {
pub(crate) options: Arc<LsmStorageOptions>,
pub(crate) compaction_controller: CompactionController,
pub(crate) manifest: Option<Manifest>,
pub(crate) ts: Arc<AtomicU64>,
pub(crate) write_lock: Mutex<()>,
}
/// A thin wrapper for `LsmStorageInner` and the user interface for MiniLSM.
@@ -405,6 +407,8 @@ impl LsmStorageInner {
compaction_controller,
manifest: Some(manifest),
options: options.into(),
ts: Arc::new(AtomicU64::new(0)),
write_lock: Mutex::new(()),
};
storage.sync_dir()?;
@@ -422,25 +426,18 @@ impl LsmStorageInner {
Arc::clone(&guard)
}; // drop global lock here
// Search on the current memtable.
if let Some(value) = snapshot.memtable.get(key) {
if value.is_empty() {
// found tomestone, return key not exists
return Ok(None);
}
return Ok(Some(value));
}
// Search on immutable memtables.
let mut memtable_iters = Vec::with_capacity(snapshot.imm_memtables.len() + 1);
memtable_iters.push(Box::new(snapshot.memtable.scan(
Bound::Included(KeySlice::from_slice(key, key::TS_RANGE_BEGIN)),
Bound::Included(KeySlice::from_slice(key, key::TS_RANGE_END)),
)));
for memtable in snapshot.imm_memtables.iter() {
if let Some(value) = memtable.get(key) {
if value.is_empty() {
// found tomestone, return key not exists
return Ok(None);
}
return Ok(Some(value));
}
memtable_iters.push(Box::new(memtable.scan(
Bound::Included(KeySlice::from_slice(key, key::TS_RANGE_BEGIN)),
Bound::Included(KeySlice::from_slice(key, key::TS_RANGE_END)),
)));
}
let memtable_iter = MergeIterator::create(memtable_iters);
let mut l0_iters = Vec::with_capacity(snapshot.l0_sstables.len());
@@ -466,7 +463,7 @@ impl LsmStorageInner {
if keep_table(key, &table) {
l0_iters.push(Box::new(SsTableIterator::create_and_seek_to_key(
table,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?));
}
}
@@ -482,20 +479,29 @@ impl LsmStorageInner {
}
let level_iter = SstConcatIterator::create_and_seek_to_key(
level_ssts,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?;
level_iters.push(Box::new(level_iter));
}
let iter = TwoMergeIterator::create(l0_iter, MergeIterator::create(level_iters))?;
let iter = LsmIterator::new(
TwoMergeIterator::create(
TwoMergeIterator::create(memtable_iter, l0_iter)?,
MergeIterator::create(level_iters),
)?,
Bound::Unbounded,
self.ts.load(Ordering::SeqCst),
)?;
if iter.is_valid() && iter.key().key_ref() == key && !iter.value().is_empty() {
if iter.is_valid() && iter.key() == key && !iter.value().is_empty() {
return Ok(Some(Bytes::copy_from_slice(iter.value())));
}
Ok(None)
}
pub fn write_batch<T: AsRef<[u8]>>(&self, batch: &[WriteBatchRecord<T>]) -> Result<()> {
let _lck = self.write_lock.lock();
let ts = self.ts.fetch_add(1, Ordering::Relaxed);
for record in batch {
match record {
WriteBatchRecord::Del(key) => {
@@ -504,7 +510,7 @@ impl LsmStorageInner {
let size;
{
let guard = self.state.read();
guard.memtable.put(key, b"")?;
guard.memtable.put(KeySlice::from_slice(key, ts), b"")?;
size = guard.memtable.approximate_size();
}
self.try_freeze(size)?;
@@ -517,7 +523,7 @@ impl LsmStorageInner {
let size;
{
let guard = self.state.read();
guard.memtable.put(key, value)?;
guard.memtable.put(KeySlice::from_slice(key, ts), value)?;
size = guard.memtable.approximate_size();
}
self.try_freeze(size)?;
@@ -681,9 +687,15 @@ impl LsmStorageInner {
}; // drop global lock here
let mut memtable_iters = Vec::with_capacity(snapshot.imm_memtables.len() + 1);
memtable_iters.push(Box::new(snapshot.memtable.scan(lower, upper)));
memtable_iters.push(Box::new(snapshot.memtable.scan(
map_key_bound_plus_ts(lower, key::TS_RANGE_BEGIN),
map_key_bound_plus_ts(upper, key::TS_RANGE_END),
)));
for memtable in snapshot.imm_memtables.iter() {
memtable_iters.push(Box::new(memtable.scan(lower, upper)));
memtable_iters.push(Box::new(memtable.scan(
map_key_bound_plus_ts(lower, key::TS_RANGE_BEGIN),
map_key_bound_plus_ts(upper, key::TS_RANGE_END),
)));
}
let memtable_iter = MergeIterator::create(memtable_iters);
@@ -699,12 +711,12 @@ impl LsmStorageInner {
let iter = match lower {
Bound::Included(key) => SsTableIterator::create_and_seek_to_key(
table,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?,
Bound::Excluded(key) => {
let mut iter = SsTableIterator::create_and_seek_to_key(
table,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?;
if iter.is_valid() && iter.key().key_ref() == key {
iter.next()?;
@@ -737,12 +749,12 @@ impl LsmStorageInner {
let level_iter = match lower {
Bound::Included(key) => SstConcatIterator::create_and_seek_to_key(
level_ssts,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?,
Bound::Excluded(key) => {
let mut iter = SstConcatIterator::create_and_seek_to_key(
level_ssts,
KeySlice::from_slice(key, key::TS_DEFAULT),
KeySlice::from_slice(key, key::TS_RANGE_BEGIN),
)?;
if iter.is_valid() && iter.key().key_ref() == key {
iter.next()?;
@@ -760,6 +772,7 @@ impl LsmStorageInner {
Ok(FusedIterator::new(LsmIterator::new(
iter,
map_bound(upper),
self.ts.load(Ordering::SeqCst),
)?))
}
}

97
mini-lsm-mvcc/src/mem_table.rs
View File

@@ -10,7 +10,7 @@ use crossbeam_skiplist::SkipMap;
use ouroboros::self_referencing;
use crate::iterators::StorageIterator;
use crate::key::{self, KeySlice};
use crate::key::{KeyBytes, KeySlice, TS_DEFAULT};
use crate::table::SsTableBuilder;
use crate::wal::Wal;
@@ -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<Bytes, Bytes>>,
map: Arc<SkipMap<KeyBytes, Bytes>>,
wal: Option<Wal>,
id: usize,
approximate_size: Arc<AtomicUsize>,
@@ -34,6 +34,30 @@ pub(crate) fn map_bound(bound: Bound<&[u8]>) -> Bound<Bytes> {
}
}
/// Create a bound of `Bytes` from a bound of `KeySlice`.
pub(crate) fn map_key_bound(bound: Bound<KeySlice>) -> Bound<KeyBytes> {
match bound {
Bound::Included(x) => Bound::Included(KeyBytes::from_bytes_with_ts(
Bytes::copy_from_slice(x.key_ref()),
x.ts(),
)),
Bound::Excluded(x) => Bound::Excluded(KeyBytes::from_bytes_with_ts(
Bytes::copy_from_slice(x.key_ref()),
x.ts(),
)),
Bound::Unbounded => Bound::Unbounded,
}
}
/// Create a bound of `Bytes` from a bound of `KeySlice`.
pub(crate) fn map_key_bound_plus_ts(bound: Bound<&[u8]>, ts: u64) -> Bound<KeySlice> {
match bound {
Bound::Included(x) => Bound::Included(KeySlice::from_slice(x, ts)),
Bound::Excluded(x) => Bound::Excluded(KeySlice::from_slice(x, ts)),
Bound::Unbounded => Bound::Unbounded,
}
}
impl MemTable {
/// Create a new mem-table.
pub fn create(id: usize) -> Self {
@@ -66,19 +90,44 @@ impl MemTable {
})
}
/// Get a value by key.
pub fn get(&self, key: &[u8]) -> Option<Bytes> {
self.map.get(key).map(|e| e.value().clone())
/// Get a value by key. Should not be used in week 3.
pub fn get(&self, key: KeySlice) -> Option<Bytes> {
let key_bytes = KeyBytes::from_bytes_with_ts(
Bytes::from_static(unsafe { std::mem::transmute(key.key_ref()) }),
key.ts(),
);
self.map.get(&key_bytes).map(|e| e.value().clone())
}
pub fn for_testing_put_slice(&self, key: &[u8], value: &[u8]) -> Result<()> {
self.put(KeySlice::from_slice(key, TS_DEFAULT), value)
}
pub fn for_testing_get_slice(&self, key: &[u8]) -> Option<Bytes> {
self.get(KeySlice::from_slice(key, TS_DEFAULT))
}
pub fn for_testing_scan_slice(
&self,
lower: Bound<&[u8]>,
upper: Bound<&[u8]>,
) -> MemTableIterator {
self.scan(
map_key_bound_plus_ts(lower, TS_DEFAULT),
map_key_bound_plus_ts(upper, TS_DEFAULT),
)
}
/// Put a key-value pair into the mem-table.
///
/// In week 1, day 1, simply put the key-value pair into the skipmap.
/// In week 2, day 6, also flush the data to WAL.
pub fn put(&self, key: &[u8], value: &[u8]) -> Result<()> {
let estimated_size = key.len() + value.len();
self.map
.insert(Bytes::copy_from_slice(key), Bytes::copy_from_slice(value));
pub fn put(&self, key: KeySlice, value: &[u8]) -> Result<()> {
let estimated_size = key.raw_len() + value.len();
self.map.insert(
key.to_key_vec().into_key_bytes(),
Bytes::copy_from_slice(value),
);
self.approximate_size
.fetch_add(estimated_size, std::sync::atomic::Ordering::Relaxed);
if let Some(ref wal) = self.wal {
@@ -95,12 +144,12 @@ impl MemTable {
}
/// Get an iterator over a range of keys.
pub fn scan(&self, lower: Bound<&[u8]>, upper: Bound<&[u8]>) -> MemTableIterator {
let (lower, upper) = (map_bound(lower), map_bound(upper));
pub fn scan(&self, lower: Bound<KeySlice>, upper: Bound<KeySlice>) -> MemTableIterator {
let (lower, upper) = (map_key_bound(lower), map_key_bound(upper));
let mut iter = MemTableIteratorBuilder {
map: self.map.clone(),
iter_builder: |map| map.range((lower, upper)),
item: (Bytes::new(), Bytes::new()),
item: (KeyBytes::new(), Bytes::new()),
}
.build();
let entry = iter.with_iter_mut(|iter| MemTableIterator::entry_to_item(iter.next()));
@@ -111,10 +160,7 @@ impl MemTable {
/// Flush the mem-table to SSTable. Implement in week 1 day 6.
pub fn flush(&self, builder: &mut SsTableBuilder) -> Result<()> {
for entry in self.map.iter() {
builder.add(
KeySlice::from_slice(&entry.key()[..], key::TS_DEFAULT),
&entry.value()[..],
);
builder.add(entry.key().as_key_slice(), &entry.value()[..]);
}
Ok(())
}
@@ -134,8 +180,13 @@ impl MemTable {
}
}
type SkipMapRangeIter<'a> =
crossbeam_skiplist::map::Range<'a, Bytes, (Bound<Bytes>, Bound<Bytes>), Bytes, Bytes>;
type SkipMapRangeIter<'a> = crossbeam_skiplist::map::Range<
'a,
KeyBytes,
(Bound<KeyBytes>, Bound<KeyBytes>),
KeyBytes,
Bytes,
>;
/// An iterator over a range of `SkipMap`. This is a self-referential structure and please refer to week 1, day 2
/// chapter for more information.
@@ -144,20 +195,20 @@ type SkipMapRangeIter<'a> =
#[self_referencing]
pub struct MemTableIterator {
/// Stores a reference to the skipmap.
map: Arc<SkipMap<Bytes, Bytes>>,
map: Arc<SkipMap<KeyBytes, Bytes>>,
/// Stores a skipmap iterator that refers to the lifetime of `MemTableIterator` itself.
#[borrows(map)]
#[not_covariant]
iter: SkipMapRangeIter<'this>,
/// Stores the current key-value pair.
item: (Bytes, Bytes),
item: (KeyBytes, Bytes),
}
impl MemTableIterator {
fn entry_to_item(entry: Option<Entry<'_, Bytes, Bytes>>) -> (Bytes, Bytes) {
fn entry_to_item(entry: Option<Entry<'_, KeyBytes, Bytes>>) -> (KeyBytes, Bytes) {
entry
.map(|x| (x.key().clone(), x.value().clone()))
.unwrap_or_else(|| (Bytes::from_static(&[]), Bytes::from_static(&[])))
.unwrap_or_else(|| (KeyBytes::new(), Bytes::new()))
}
}
@@ -169,7 +220,7 @@ impl StorageIterator for MemTableIterator {
}
fn key(&self) -> KeySlice {
KeySlice::from_slice(&self.borrow_item().0[..], key::TS_DEFAULT)
self.borrow_item().0.as_key_slice()
}
fn is_valid(&self) -> bool {

2
mini-lsm-mvcc/src/table/builder.rs
View File

@@ -70,7 +70,9 @@ impl SsTableBuilder {
first_key: std::mem::take(&mut self.first_key).into_key_bytes(),
last_key: std::mem::take(&mut self.last_key).into_key_bytes(),
});
let checksum = crc32fast::hash(&encoded_block);
self.data.extend(encoded_block);
self.data.put_u32(checksum);
}
/// Builds the SSTable and writes it to the given path. Use the `FileObject` structure to manipulate the disk objects.

8
mini-lsm-mvcc/src/tests.rs
View File

@@ -6,7 +6,7 @@ mod week1_day4;
mod week1_day5;
mod week1_day6;
mod week1_day7;
mod week2_day1;
mod week2_day2;
mod week2_day3;
mod week2_day4;
// mod week2_day1;
// mod week2_day2;
// mod week2_day3;
// mod week2_day4;

22
mini-lsm-mvcc/src/wal.rs
View File

@@ -9,6 +9,8 @@ use bytes::{Buf, BufMut, Bytes};
use crossbeam_skiplist::SkipMap;
use parking_lot::Mutex;
use crate::key::{KeyBytes, KeySlice};
pub struct Wal {
file: Arc<Mutex<File>>,
}
@@ -27,7 +29,7 @@ impl Wal {
})
}
pub fn recover(path: impl AsRef<Path>, skiplist: &SkipMap<Bytes, Bytes>) -> Result<Self> {
pub fn recover(path: impl AsRef<Path>, skiplist: &SkipMap<KeyBytes, Bytes>) -> Result<Self> {
let path = path.as_ref();
let mut file = OpenOptions::new()
.read(true)
@@ -44,6 +46,8 @@ impl Wal {
let key = Bytes::copy_from_slice(&rbuf[..key_len]);
hasher.write(&key);
rbuf.advance(key_len);
let ts = rbuf.get_u64();
hasher.write_u64(ts);
let value_len = rbuf.get_u16() as usize;
hasher.write_u16(value_len as u16);
let value = Bytes::copy_from_slice(&rbuf[..value_len]);
@@ -53,22 +57,24 @@ impl Wal {
if hasher.finalize() != checksum {
bail!("checksum mismatch");
}
skiplist.insert(key, value);
skiplist.insert(KeyBytes::from_bytes_with_ts(key, ts), value);
}
Ok(Self {
file: Arc::new(Mutex::new(file)),
})
}
pub fn put(&self, key: &[u8], value: &[u8]) -> Result<()> {
pub fn put(&self, key: KeySlice, value: &[u8]) -> Result<()> {
let mut file = self.file.lock();
let mut buf: Vec<u8> =
Vec::with_capacity(key.len() + value.len() + std::mem::size_of::<u16>());
Vec::with_capacity(key.raw_len() + value.len() + std::mem::size_of::<u16>());
let mut hasher = crc32fast::Hasher::new();
hasher.write_u16(key.len() as u16);
buf.put_u16(key.len() as u16);
hasher.write(key);
buf.put_slice(key);
hasher.write_u16(key.key_len() as u16);
buf.put_u16(key.key_len() as u16);
hasher.write(key.key_ref());
buf.put_slice(key.key_ref());
hasher.write_u64(key.ts());
buf.put_u64(key.ts());
hasher.write_u16(value.len() as u16);
buf.put_u16(value.len() as u16);
buf.put_slice(value);