125 lines
3.3 KiB
Rust
125 lines
3.3 KiB
Rust
// Copyright (c) 2022-2025 Alex Chi Z
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#![allow(unused_variables)] // TODO(you): remove this lint after implementing this mod
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#![allow(dead_code)] // TODO(you): remove this lint after implementing this mod
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use anyhow::Result;
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use crate::{
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iterators::{StorageIterator, merge_iterator::MergeIterator},
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mem_table::MemTableIterator,
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};
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/// Represents the internal type for an LSM iterator. This type will be changed across the course for multiple times.
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type LsmIteratorInner = MergeIterator<MemTableIterator>;
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pub struct LsmIterator {
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inner: LsmIteratorInner,
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}
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impl LsmIterator {
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pub(crate) fn new(iter: LsmIteratorInner) -> Result<Self> {
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Ok(Self { inner: iter })
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}
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}
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impl StorageIterator for LsmIterator {
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type KeyType<'a> = &'a [u8];
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fn is_valid(&self) -> bool {
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self.inner.is_valid()
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}
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fn key(&self) -> &[u8] {
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self.inner.key().into_inner()
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}
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fn value(&self) -> &[u8] {
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self.inner.value()
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}
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fn next(&mut self) -> Result<()> {
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// TODO: I dont know if I need use ? to return the Error or not
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self.inner.next()?;
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// 跳过已经删除的key
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while self.inner.is_valid() && self.inner.value().is_empty() {
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self.inner.next()?;
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}
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Ok(())
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}
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}
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/// A wrapper around existing iterator, will prevent users from calling `next` when the iterator is
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/// invalid. If an iterator is already invalid, `next` does not do anything. If `next` returns an error,
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/// `is_valid` should return false, and `next` should always return an error.
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pub struct FusedIterator<I: StorageIterator> {
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iter: I,
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has_errored: bool,
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}
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impl<I: StorageIterator> FusedIterator<I> {
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pub fn new(iter: I) -> Self {
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Self {
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iter,
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has_errored: false,
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}
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}
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}
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impl<I: StorageIterator> StorageIterator for FusedIterator<I> {
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type KeyType<'a>
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= I::KeyType<'a>
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where
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Self: 'a;
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fn is_valid(&self) -> bool {
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// self.iter.is_valid() && !self.has_errored
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if self.has_errored {
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false
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} else {
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self.iter.is_valid()
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}
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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 value(&self) -> &[u8] {
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self.iter.value()
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}
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fn next(&mut self) -> Result<()> {
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// 按照测试用例，出现错误就要返回err
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if self.has_errored {
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return Err(anyhow::anyhow!("iterator has errored previously"));
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}
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// 但是对于迭代器已经失效，不应该报错
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if !self.iter.is_valid() {
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return Ok(());
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}
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//
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match self.iter.next() {
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Ok(()) => Ok(()),
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Err(e) => {
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self.has_errored = true;
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Err(e)
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}
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}
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}
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}
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