667 lines
22 KiB
Rust
667 lines
22 KiB
Rust
use std::collections::HashSet;
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use std::io;
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use std::path::Path;
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use serde::de::{IgnoredAny, MapAccess, Visitor};
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use serde::Deserializer;
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use crate::btree::DiskBTree;
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use crate::page::PageId;
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use crate::page::{Page, PageFile};
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use crate::protocol::Row;
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// 堆表：行按插入顺序进页，支持全表扫描、按索引取行、行级删除。
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const HEADER_SIZE: usize = 2;
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const SLOT_SIZE: usize = 8;
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const SLOT_DIR_START: usize = HEADER_SIZE;
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/// 未选字段只校验并跳过，不分配值。
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fn decode_row(bytes: &[u8], columns: Option<&[String]>, hidden: &HashSet<String>) -> io::Result<Row> {
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struct RowVisitor<'a>(Option<&'a [String]>, &'a HashSet<String>);
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impl<'de> Visitor<'de> for RowVisitor<'_> {
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type Value = Row;
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fn expecting(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
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f.write_str("a row object")
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}
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fn visit_map<M: MapAccess<'de>>(self, mut map: M) -> Result<Row, M::Error> {
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let mut row = Row::new();
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while let Some(key) = map.next_key::<String>()? {
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if !self.1.contains(&key) && self.0.is_none_or(|cols| cols.contains(&key)) {
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row.insert(key, map.next_value()?);
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} else {
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map.next_value::<IgnoredAny>()?;
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}
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}
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Ok(row)
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}
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}
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let mut decoder = serde_json::Deserializer::from_slice(bytes);
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let row = decoder.deserialize_map(RowVisitor(columns, hidden)).map_err(io::Error::other)?;
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decoder.end().map_err(io::Error::other)?;
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Ok(row)
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}
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/// 读一个小端 u16
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fn read_u16(buf: &[u8], off: usize) -> u16 {
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u16::from_le_bytes([buf[off], buf[off + 1]])
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}
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/// 写一个小端 u16
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fn write_u16(buf: &mut [u8], off: usize, v: u16) {
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buf[off..off + 2].copy_from_slice(&v.to_le_bytes());
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}
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/// 读一个小端 u32
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fn read_u32(buf: &[u8], off: usize) -> u32 {
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u32::from_le_bytes([buf[off], buf[off + 1], buf[off + 2], buf[off + 3]])
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}
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/// 写一个小端 u32
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fn write_u32(buf: &mut [u8], off: usize, v: u32) {
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buf[off..off + 4].copy_from_slice(&v.to_le_bytes());
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}
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/// (页号, 槽位号) 打包成 u64
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fn pack_position(page_id: PageId, slot: u16) -> u64 {
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(page_id << 16) | (slot as u64)
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}
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/// 从 u64 解回 (页号, 槽位号)
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fn unpack_position(v: u64) -> (PageId, u16) {
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(v >> 16, (v & 0xFFFF) as u16)
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}
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/// 取行里某一列的整数值（不是整数就没有）
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fn row_int(row: &Row, column: &str) -> Option<i64> {
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match row.get(column) {
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Some(serde_json::Value::Number(n)) => n.as_i64(),
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_ => None,
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}
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}
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/// i64 键 → 8 字节大端（保序，负数也在前）
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fn key_of(value: i64) -> [u8; 8] {
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(value as u64 ^ (1u64 << 63)).to_be_bytes()
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}
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/// JSON 值 → 索引键字节（与写索引时同一套编码）
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fn value_key(v: &serde_json::Value) -> Option<Vec<u8>> {
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match v {
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serde_json::Value::Number(n) => n.as_i64().map(|k| key_of(k).to_vec()),
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serde_json::Value::String(s) => Some(s.as_bytes().to_vec()),
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serde_json::Value::Bool(b) => Some(vec![u8::from(*b)]),
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_ => None,
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}
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}
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/// 取行里某一列的索引键；NULL 与缺列不入索引
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fn row_key(row: &Row, column: &str) -> Option<Vec<u8>> {
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row.get(column).and_then(value_key)
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}
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pub struct HeapPage;
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impl HeapPage {
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/// 这一页有几个槽位
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pub fn slot_count(page: &Page) -> u16 {
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read_u16(&page.data, 0)
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}
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/// 改写槽位数量
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fn set_slot_count(page: &mut Page, v: u16) {
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write_u16(&mut page.data, 0, v);
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}
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/// 空闲空间下界
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fn free_start(page: &Page) -> usize {
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SLOT_DIR_START + (Self::slot_count(page) as usize) * SLOT_SIZE
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}
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/// 空闲空间上界
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fn free_end(page: &Page) -> usize {
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let n = Self::slot_count(page);
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let mut min_off = page.data.len() as u32;
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for i in 0..n as usize {
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let slot_off = SLOT_DIR_START + i * SLOT_SIZE;
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let off = read_u32(&page.data, slot_off);
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let len = read_u32(&page.data, slot_off + 4);
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if len > 0 && off < min_off {
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min_off = off;
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}
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}
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min_off as usize
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}
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/// 试插一行，放不下返回 None
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pub fn insert_tuple(page: &mut Page, tuple: &[u8]) -> Option<u16> {
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let n = Self::slot_count(page);
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let free_start = Self::free_start(page);
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let free_end = Self::free_end(page);
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if free_start + SLOT_SIZE + tuple.len() > free_end {
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return None;
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}
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let tuple_off = free_end - tuple.len();
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page.data[tuple_off..tuple_off + tuple.len()].copy_from_slice(tuple);
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let slot_off = SLOT_DIR_START + (n as usize) * SLOT_SIZE;
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write_u32(&mut page.data, slot_off, tuple_off as u32);
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write_u32(&mut page.data, slot_off + 4, tuple.len() as u32);
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Self::set_slot_count(page, n + 1);
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Some(n)
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}
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/// 删掉一个槽位，只把长度置 0
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pub fn delete_tuple(page: &mut Page, slot: u16) -> bool {
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let n = Self::slot_count(page);
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if slot >= n {
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return false;
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}
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let slot_off = SLOT_DIR_START + (slot as usize) * SLOT_SIZE;
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if read_u32(&page.data, slot_off + 4) == 0 {
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return false;
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}
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write_u32(&mut page.data, slot_off + 4, 0);
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true
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}
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/// 读槽位里的行字节
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pub fn get_tuple(page: &Page, slot: u16) -> Option<Vec<u8>> {
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let n = Self::slot_count(page);
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if slot >= n {
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return None;
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}
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let slot_off = SLOT_DIR_START + (slot as usize) * SLOT_SIZE;
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let off = read_u32(&page.data, slot_off) as usize;
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let len = read_u32(&page.data, slot_off + 4) as usize;
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if len == 0 {
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return None;
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}
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Some(page.data[off..off + len].to_vec())
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}
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/// 所有槽位号
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pub fn iter_slots(page: &Page) -> Vec<u16> {
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(0..Self::slot_count(page)).collect()
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}
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}
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struct NamedIndex {
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column: String,
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tree: DiskBTree,
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}
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pub struct HeapTable {
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hidden_columns: HashSet<String>,
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file: PageFile,
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indexes: Vec<NamedIndex>,
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}
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impl HeapTable {
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/// 打开表（不带索引）
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pub fn open<P: AsRef<Path>>(path: P, page_size: usize, pool_size: usize) -> io::Result<Self> {
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Ok(HeapTable {
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hidden_columns: HashSet::new(),
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file: PageFile::with_options(path, page_size, pool_size)?,
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indexes: Vec::new(),
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})
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}
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/// 打开表并挂上 id 列索引
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pub fn open_indexed<P: AsRef<Path>, Q: AsRef<Path>>(
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path: P,
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index_path: Q,
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page_size: usize,
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btree_order: usize,
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pool_size: usize,
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) -> io::Result<Self> {
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Self::open_with_indexes(
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path,
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&[("id".to_string(), index_path.as_ref().to_path_buf())],
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page_size,
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btree_order,
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pool_size,
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)
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}
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/// 打开表并挂上多组索引
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pub fn open_with_indexes<P: AsRef<Path>>(
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path: P,
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indexes: &[(String, std::path::PathBuf)],
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page_size: usize,
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btree_order: usize,
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pool_size: usize,
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) -> io::Result<Self> {
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let mut t = HeapTable {
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hidden_columns: HashSet::new(),
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file: PageFile::with_options(path, page_size, pool_size)?,
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indexes: Vec::new(),
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};
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let mut filled = false;
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for (col, p) in indexes {
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match t.attach_index(col, p, page_size, btree_order, pool_size) {
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Ok(()) => {}
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Err(err) if err.kind() == io::ErrorKind::InvalidData => {
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// 格式不兼容（例如上一版落的索引文件）：删掉重开
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let _ = std::fs::remove_file(p);
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t.attach_index(col, p, page_size, btree_order, pool_size)?;
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}
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Err(err) => return Err(err),
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}
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// 空索引（新文件、被截断、强杀留下）都按堆数据补齐
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if t.index_empty(col)? {
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t.fill_index(col)?;
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filled = true;
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}
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}
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if filled {
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t.flush()?;
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}
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Ok(t)
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}
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/// 挂上一棵索引树，不填数据
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fn attach_index<P: AsRef<Path>>(
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&mut self,
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column: &str,
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path: P,
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page_size: usize,
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btree_order: usize,
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pool_size: usize,
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) -> io::Result<()> {
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let tree = DiskBTree::open(path, page_size, btree_order, pool_size)?;
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self.indexes.push(NamedIndex {
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column: column.to_string(),
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tree,
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});
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Ok(())
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}
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/// 这一列有索引吗
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pub fn has_index(&self, column: &str) -> bool {
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self.indexes.iter().any(|i| i.column == column)
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}
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/// 建索引：要求这一列取值唯一
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pub fn build_index(
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&mut self,
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column: &str,
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path: &Path,
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page_size: usize,
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btree_order: usize,
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pool_size: usize,
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) -> io::Result<()> {
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if self.has_index(column) {
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return Err(io::Error::new(
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io::ErrorKind::AlreadyExists,
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format!("index on column \"{}\" already exists", column),
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));
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}
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let mut seen: HashSet<Vec<u8>> = HashSet::new();
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let mut entries: Vec<(Vec<u8>, u64)> = Vec::new();
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for (page_id, slot, r) in self.scan_with_positions()? {
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let Some(k) = row_key(&r, column) else {
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continue;
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};
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// 行身份索引仍然唯一；其余列允许重复值
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if column == "id" && !seen.insert(k.clone()) {
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return Err(io::Error::new(
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io::ErrorKind::InvalidInput,
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format!("column \"{}\" has duplicate values", column),
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));
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}
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entries.push((k, pack_position(page_id, slot)));
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}
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self.attach_index(column, path, page_size, btree_order, pool_size)?;
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let i = self.indexes.len() - 1;
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self.indexes[i].tree.clear()?;
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for (k, pos) in entries {
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self.indexes[i].tree.insert(&k, pos)?;
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}
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Ok(())
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}
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/// 这一列的索引是空的吗
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fn index_empty(&mut self, column: &str) -> io::Result<bool> {
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match self.indexes.iter_mut().find(|i| i.column == column) {
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Some(idx) => idx.tree.is_empty(),
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None => Ok(false),
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}
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}
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/// 按堆里的行把某一列索引补齐
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fn fill_index(&mut self, column: &str) -> io::Result<()> {
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let rows = self.scan_with_positions()?;
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let Some(i) = self.indexes.iter().position(|idx| idx.column == column) else {
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return Ok(());
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};
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for (page_id, slot, row) in rows {
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if let Some(k) = row_key(&row, column) {
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self.indexes[i]
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.tree
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.insert(&k, pack_position(page_id, slot))?;
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}
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}
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Ok(())
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}
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/// 摘掉一个索引（不删文件）
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pub fn detach_index(&mut self, column: &str) -> bool {
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match self.indexes.iter().position(|i| i.column == column) {
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None => false,
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Some(i) => {
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self.indexes.remove(i);
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true
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}
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}
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}
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pub fn set_hidden_columns(&mut self, columns: HashSet<String>) {
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self.hidden_columns = columns;
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}
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pub fn hide_column(&mut self, column: &str) {
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self.detach_index(column);
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self.hidden_columns.insert(column.to_string());
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}
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/// 插入一行，并顺手写各索引
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pub fn insert_row(&mut self, row: &Row) -> io::Result<()> {
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self.insert_row_returning_position(row).map(|_| ())
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}
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/// 插入一行并返回它的位置
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pub fn insert_row_returning_position(&mut self, row: &Row) -> io::Result<(PageId, u16)> {
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let mut pending: Vec<(usize, Vec<u8>)> = Vec::new();
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for (i, idx) in self.indexes.iter_mut().enumerate() {
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let Some(k) = row_key(row, &idx.column) else {
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continue;
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};
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if idx.column == "id" && idx.tree.get(&k)?.is_some() {
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return Err(io::Error::new(
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io::ErrorKind::InvalidInput,
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"duplicate value on the id index".to_string(),
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));
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}
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pending.push((i, k));
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}
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let (page_id, slot) = self.insert_returning_position(row)?;
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let pos = pack_position(page_id, slot);
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for (i, k) in pending {
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self.indexes[i].tree.insert(&k, pos)?;
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}
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Ok((page_id, slot))
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}
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/// 批量插入，落盘由调用方负责
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pub fn insert_rows(&mut self, rows: &[Row]) -> io::Result<()> {
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for r in rows {
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self.insert_row(r)?;
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}
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Ok(())
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}
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/// 编码并验证一行能放进页
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pub fn encode_row(row: &Row, page_size: usize) -> io::Result<Vec<u8>> {
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let tuple = serde_json::to_vec(row).map_err(io::Error::other)?;
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if HEADER_SIZE + SLOT_SIZE + tuple.len() > page_size {
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return Err(io::Error::other(format!(
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"tuple too large: {} bytes",
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tuple.len()
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)));
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}
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Ok(tuple)
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}
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/// 插入一行，只进堆表、不碰索引
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fn insert_returning_position(&mut self, row: &Row) -> io::Result<(PageId, u16)> {
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let tuple = Self::encode_row(row, self.file.page_size())?;
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let n = self.file.num_pages()?;
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if n > 0 {
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let last_id = n - 1;
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let mut slot = None;
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self.file.update_page(last_id, |p| {
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slot = HeapPage::insert_tuple(p, &tuple);
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})?;
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if let Some(s) = slot {
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return Ok((last_id, s));
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}
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}
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let mut p = self.file.append_page()?;
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let page_id = p.id;
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let slot = HeapPage::insert_tuple(&mut p, &tuple).expect("pre-checked fits");
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self.file.write_page(&p)?;
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Ok((page_id, slot))
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}
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/// 按 `id` 取一行
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pub fn get_by_key(&mut self, key: i64) -> io::Result<Option<Row>> {
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self.get_by_column_key("id", key)
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}
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/// 按某一列的整数索引取一行
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pub fn get_by_column_key(&mut self, column: &str, key: i64) -> io::Result<Option<Row>> {
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self.get_by_bytes(column, &key_of(key))
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}
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/// 按某一列的字符串索引取一行
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pub fn get_by_string_key(&mut self, column: &str, key: &str) -> io::Result<Option<Row>> {
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self.get_by_bytes(column, key.as_bytes())
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}
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/// 按某一列的整数索引取全部行
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pub fn get_all_by_column_key(&mut self, column: &str, key: i64) -> io::Result<Vec<Row>> {
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self.get_all_by_bytes(column, &key_of(key))
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}
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/// 按某一列的字符串索引取全部行
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pub fn get_all_by_string_key(&mut self, column: &str, key: &str) -> io::Result<Vec<Row>> {
|
|
self.get_all_by_bytes(column, key.as_bytes())
|
|
}
|
|
|
|
/// 按索引键的字节取第一行
|
|
fn get_by_bytes(&mut self, column: &str, key: &[u8]) -> io::Result<Option<Row>> {
|
|
Ok(self.get_all_by_bytes(column, key)?.into_iter().next())
|
|
}
|
|
|
|
/// 按索引键的字节取全部行（重复值都给出来）
|
|
fn get_all_by_bytes(&mut self, column: &str, key: &[u8]) -> io::Result<Vec<Row>> {
|
|
let Some(idx) = self.indexes.iter_mut().find(|i| i.column == column) else {
|
|
return Ok(Vec::new());
|
|
};
|
|
let positions = idx.tree.get_all(key)?;
|
|
let mut rows = Vec::new();
|
|
for pos in positions {
|
|
let (page_id, slot) = unpack_position(pos);
|
|
if let Some(row) = self.read_at(page_id, slot)? {
|
|
rows.push(row);
|
|
}
|
|
}
|
|
Ok(rows)
|
|
}
|
|
|
|
/// 范围扫描：某一列有索引就走叶子链，没有索引返回 None（上层退回全表扫描）
|
|
pub fn scan_range(
|
|
&mut self,
|
|
column: &str,
|
|
lo: Option<(&serde_json::Value, bool)>,
|
|
hi: Option<(&serde_json::Value, bool)>,
|
|
) -> io::Result<Option<Vec<Row>>> {
|
|
let Some(i) = self.indexes.iter().position(|idx| idx.column == column) else {
|
|
return Ok(None);
|
|
};
|
|
let lo_bound = lo.and_then(|(v, inclusive)| value_key(v).map(|k| (k, inclusive)));
|
|
let hi_bound = hi.and_then(|(v, inclusive)| value_key(v).map(|k| (k, inclusive)));
|
|
// 树按闭区间取，排他端在取回来之后再筛
|
|
let pairs = self.indexes[i].tree.scan(
|
|
lo_bound.as_ref().map(|(k, _)| k.as_slice()),
|
|
hi_bound.as_ref().map(|(k, _)| k.as_slice()),
|
|
)?;
|
|
let mut rows = Vec::new();
|
|
for (key, pos) in pairs {
|
|
if let Some((bound, inclusive)) = &lo_bound {
|
|
let outside = if *inclusive { &key < bound } else { &key <= bound };
|
|
if outside {
|
|
continue;
|
|
}
|
|
}
|
|
if let Some((bound, inclusive)) = &hi_bound {
|
|
let outside = if *inclusive { &key > bound } else { &key >= bound };
|
|
if outside {
|
|
continue;
|
|
}
|
|
}
|
|
let (page_id, slot) = unpack_position(pos);
|
|
if let Some(row) = self.read_at(page_id, slot)? {
|
|
rows.push(row);
|
|
}
|
|
}
|
|
Ok(Some(rows))
|
|
}
|
|
|
|
/// 按位置读一行
|
|
pub fn read_at(&mut self, page_id: PageId, slot: u16) -> io::Result<Option<Row>> {
|
|
let bytes = self.file.with_page(page_id, |p| HeapPage::get_tuple(p, slot))?;
|
|
match bytes {
|
|
None => Ok(None),
|
|
Some(bytes) => {
|
|
let row = decode_row(&bytes, None, &self.hidden_columns)?;
|
|
Ok(Some(row))
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 按位置删一行并返回它
|
|
pub fn delete_at(&mut self, page_id: PageId, slot: u16) -> io::Result<Option<Row>> {
|
|
let row = self.read_at(page_id, slot)?;
|
|
let existed = self.file.update_page(page_id, |p| HeapPage::delete_tuple(p, slot))?;
|
|
if !existed {
|
|
return Ok(None);
|
|
}
|
|
if let Some(r) = &row {
|
|
let pos = pack_position(page_id, slot);
|
|
for idx in &mut self.indexes {
|
|
if let Some(k) = row_key(r, &idx.column) {
|
|
idx.tree.delete(&k, pos)?;
|
|
}
|
|
}
|
|
}
|
|
Ok(row)
|
|
}
|
|
|
|
/// 按 id 批量删行，返回删掉的行
|
|
pub fn delete_by_keys(&mut self, keys: &[i64]) -> io::Result<Vec<Row>> {
|
|
let mut positions: Vec<(PageId, u16)> = Vec::new();
|
|
|
|
if self.has_index("id") {
|
|
for &k in keys {
|
|
let pos = self
|
|
.indexes
|
|
.iter_mut()
|
|
.find(|i| i.column == "id")
|
|
.and_then(|i| i.tree.get(&key_of(k)).ok().flatten());
|
|
if let Some(p) = pos {
|
|
positions.push(unpack_position(p));
|
|
}
|
|
}
|
|
} else {
|
|
let mut wanted: Vec<i64> = keys.to_vec();
|
|
wanted.sort_unstable();
|
|
for (page_id, slot, r) in self.scan_with_positions()? {
|
|
if row_int(&r, "id").is_some_and(|k| wanted.binary_search(&k).is_ok()) {
|
|
positions.push((page_id, slot));
|
|
}
|
|
}
|
|
}
|
|
|
|
let mut deleted: Vec<Row> = Vec::new();
|
|
for (page_id, slot) in positions {
|
|
if let Some(r) = self.delete_at(page_id, slot)? {
|
|
deleted.push(r);
|
|
}
|
|
}
|
|
Ok(deleted)
|
|
}
|
|
|
|
/// 全表扫描
|
|
pub fn scan(&mut self) -> io::Result<Vec<Row>> {
|
|
self.scan_columns(None)
|
|
}
|
|
|
|
pub fn scan_columns(&mut self, columns: Option<&[String]>) -> io::Result<Vec<Row>> {
|
|
Ok(self
|
|
.scan_projected_with_positions(columns)?
|
|
.into_iter()
|
|
.map(|(_, _, r)| r)
|
|
.collect())
|
|
}
|
|
|
|
/// 全表扫描，同时给出每行的位置（建索引用）
|
|
pub fn scan_with_positions(&mut self) -> io::Result<Vec<(PageId, u16, Row)>> {
|
|
self.scan_projected_with_positions(None)
|
|
}
|
|
|
|
fn scan_projected_with_positions(&mut self, columns: Option<&[String]>) -> io::Result<Vec<(PageId, u16, Row)>> {
|
|
let n = self.file.num_pages()?;
|
|
let mut out = Vec::new();
|
|
for i in 0..n {
|
|
let tuples = self.file.with_page(i, |p| {
|
|
let mut v = Vec::new();
|
|
for slot in HeapPage::iter_slots(p) {
|
|
if let Some(bytes) = HeapPage::get_tuple(p, slot) {
|
|
v.push((slot, bytes));
|
|
}
|
|
}
|
|
v
|
|
})?;
|
|
for (slot, bytes) in tuples {
|
|
let row = decode_row(&bytes, columns, &self.hidden_columns)?;
|
|
out.push((i, slot, row));
|
|
}
|
|
}
|
|
Ok(out)
|
|
}
|
|
|
|
/// 整表改写并重建所有索引
|
|
pub fn replace_all(&mut self, rows: &[Row]) -> io::Result<()> {
|
|
self.file.truncate()?;
|
|
for idx in &mut self.indexes {
|
|
idx.tree.clear()?;
|
|
}
|
|
for r in rows {
|
|
let (page_id, slot) = self.insert_returning_position(r)?;
|
|
let pos = pack_position(page_id, slot);
|
|
for idx in &mut self.indexes {
|
|
if let Some(k) = row_key(r, &idx.column) {
|
|
idx.tree.insert(&k, pos)?;
|
|
}
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
/// 把脏页写回（索引也一起）
|
|
pub fn flush(&mut self) -> io::Result<()> {
|
|
for idx in &mut self.indexes {
|
|
idx.tree.flush()?;
|
|
}
|
|
self.file.flush()
|
|
}
|
|
|
|
/// 当前缓存页数
|
|
pub fn cached_pages(&self) -> usize { self.file.cached_pages() }
|
|
/// 命中次数
|
|
pub fn hits(&self) -> u64 { self.file.hits() }
|
|
/// 未命中次数
|
|
pub fn misses(&self) -> u64 { self.file.misses() }
|
|
/// 命中率
|
|
pub fn hit_rate(&self) -> f64 { self.file.hit_rate() }
|
|
}
|