104 lines
2.3 KiB
Rust
104 lines
2.3 KiB
Rust
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mod watermark;
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use std::{ops::Bound, sync::Arc};
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use anyhow::Result;
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use bytes::Bytes;
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use parking_lot::Mutex;
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use crate::{
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iterators::StorageIterator,
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lsm_iterator::{FusedIterator, LsmIterator},
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lsm_storage::LsmStorageInner,
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};
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use self::watermark::Watermark;
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pub(crate) struct LsmMvccInner {
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pub(crate) write_lock: Mutex<()>,
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pub(crate) ts: Arc<Mutex<(u64, Watermark)>>,
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}
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impl LsmMvccInner {
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pub fn new(initial_ts: u64) -> Self {
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Self {
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write_lock: Mutex::new(()),
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ts: Arc::new(Mutex::new((initial_ts, Watermark::new()))),
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}
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}
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pub fn latest_commit_ts(&self) -> u64 {
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self.ts.lock().0
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}
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pub fn update_commit_ts(&self, ts: u64) {
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self.ts.lock().0 = ts;
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}
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/// All ts (strictly) below this ts can be garbage collected.
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pub fn watermark(&self) -> u64 {
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let ts = self.ts.lock();
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ts.1.watermark().unwrap_or(ts.0)
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}
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pub fn new_txn(&self, inner: Arc<LsmStorageInner>) -> Arc<Transaction> {
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let mut ts = self.ts.lock();
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let read_ts = ts.0;
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ts.1.add_reader(read_ts);
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Arc::new(Transaction { inner, read_ts })
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}
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}
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pub struct Transaction {
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read_ts: u64,
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inner: Arc<LsmStorageInner>,
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}
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impl Transaction {
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pub fn get(&self, key: &[u8]) -> Result<Option<Bytes>> {
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self.inner.get_with_ts(key, self.read_ts)
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}
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pub fn scan(self: &Arc<Self>, lower: Bound<&[u8]>, upper: Bound<&[u8]>) -> Result<TxnIterator> {
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Ok(TxnIterator {
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_txn: self.clone(),
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iter: self.inner.scan_with_ts(lower, upper, self.read_ts)?,
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})
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}
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}
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impl Drop for Transaction {
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fn drop(&mut self) {
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self.inner.mvcc().ts.lock().1.remove_reader(self.read_ts)
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}
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}
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pub struct TxnIterator {
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_txn: Arc<Transaction>,
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iter: FusedIterator<LsmIterator>,
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}
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impl StorageIterator for TxnIterator {
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type KeyType<'a> = &'a [u8] where Self: 'a;
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fn value(&self) -> &[u8] {
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self.iter.value()
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}
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fn key(&self) -> Self::KeyType<'_> {
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self.iter.key()
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}
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fn is_valid(&self) -> bool {
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self.iter.is_valid()
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}
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fn next(&mut self) -> Result<()> {
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self.iter.next()
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}
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fn num_active_iterators(&self) -> usize {
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self.iter.num_active_iterators()
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}
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}
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