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Split Cursor into ReadCursor and WriteCursor

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This commit is contained in:
Yuriy Dupyn 2024-02-03 19:00:00 +01:00
parent 53aa5a0127
commit a37c3a5e77
4 changed files with 334 additions and 40 deletions
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70
storage_engine/src/storage_engine.rs
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@ -17,7 +17,7 @@ use crate::index::Index;
use std::mem::size_of;
type Result<T> = std::result::Result<T, Error>;
pub type Result<T> = std::result::Result<T, Error>;
pub type Column = u64;
pub type FilePosition = u64;
@ -31,7 +31,7 @@ pub struct Store<T> {
// {write: 0, read: n + 1} ~> {write:0, read: n} // destroy read
// {write: 0, read: 0} ~> {write: 1, read: 0} // create write
// {write: 1, read: 0} ~> {write: 0, read: 0} // destroy write
table_folder: String,
pub table_folder: String,
// primary_index: Vec<Index<T, FilePosition>>>,
// indexes: Vec<Option<Index<T, HashSet<FilePosition>>>>,
// primary_index: Index<PositionOfValue, PositionOfRow>,
@ -39,8 +39,8 @@ pub struct Store<T> {
// TODO: It's not good to have StoreHeader copied to all the cursors, since they may modify it.
// How to sync?
// All
header: StoreHeader,
data_type: PhantomData<T>,
pub header: StoreHeader,
pub data_type: PhantomData<T>,
// meta
// location of rows file
@ -61,14 +61,6 @@ pub struct Cursor<T> {
eof_file_position: FilePosition,
}
pub struct WriteCursor<'a, T> {
header: &'a mut StoreHeader,
file: File,
data_type: PhantomData<T>,
eof_file_position: FilePosition,
}
pub enum AccessMode {
Read,
Write
@ -80,22 +72,22 @@ pub type PositionOfRow = FilePosition;
#[derive(Debug, Clone)]
pub struct StoreHeader {
number_of_columns: usize,
deleted_count: usize,
total_count: usize,
primary_column: Column,
pub number_of_columns: usize,
pub deleted_count: usize,
pub total_count: usize,
pub primary_column: Column,
}
impl StoreHeader {
const NUMBER_OF_COLUMNS_SIZE: usize = size_of::<usize>();
const DELETED_COUNT_SIZE: usize = size_of::<usize>();
const TOTAL_COUNT_SIZE: usize = size_of::<usize>();
const PRIMARY_COLUMN_SIZE: usize = size_of::<Column>();
const SIZE: usize = Self::NUMBER_OF_COLUMNS_SIZE + Self::DELETED_COUNT_SIZE + Self::TOTAL_COUNT_SIZE + Self::PRIMARY_COLUMN_SIZE;
pub const NUMBER_OF_COLUMNS_SIZE: usize = size_of::<usize>();
pub const DELETED_COUNT_SIZE: usize = size_of::<usize>();
pub const TOTAL_COUNT_SIZE: usize = size_of::<usize>();
pub const PRIMARY_COLUMN_SIZE: usize = size_of::<Column>();
pub const SIZE: usize = Self::NUMBER_OF_COLUMNS_SIZE + Self::DELETED_COUNT_SIZE + Self::TOTAL_COUNT_SIZE + Self::PRIMARY_COLUMN_SIZE;
const NUMBER_OF_COLUMNS_OFFSET: usize = 0;
const DELETED_COUNT_OFFSET: usize = Self::NUMBER_OF_COLUMNS_OFFSET + Self::NUMBER_OF_COLUMNS_SIZE;
const TOTAL_COUNT_OFFSET: usize = Self::DELETED_COUNT_OFFSET + Self::DELETED_COUNT_SIZE;
const PRIMARY_COLUMN_OFFSET: usize = Self::TOTAL_COUNT_OFFSET + Self::TOTAL_COUNT_SIZE;
pub const NUMBER_OF_COLUMNS_OFFSET: usize = 0;
pub const DELETED_COUNT_OFFSET: usize = Self::NUMBER_OF_COLUMNS_OFFSET + Self::NUMBER_OF_COLUMNS_SIZE;
pub const TOTAL_COUNT_OFFSET: usize = Self::DELETED_COUNT_OFFSET + Self::DELETED_COUNT_SIZE;
pub const PRIMARY_COLUMN_OFFSET: usize = Self::TOTAL_COUNT_OFFSET + Self::TOTAL_COUNT_SIZE;
}
#[derive(Debug)]
@ -105,21 +97,21 @@ pub struct EntryHeader {
#[derive(Debug)]
pub struct EntryHeaderWithDataSize {
is_deleted: bool,
data_sizes: Vec<usize>, // vec![5, 6, 20] means that column 0 stores 5 bytes, column 1 stores 6
pub is_deleted: bool,
pub data_sizes: Vec<usize>, // vec![5, 6, 20] means that column 0 stores 5 bytes, column 1 stores 6
// bytes etc
}
impl EntryHeaderWithDataSize {
const IS_DELETED_OFFSET: usize = 0;
const IS_DELETED_SIZE: usize = size_of::<bool>();
const DATA_SIZES_OFFSET: usize = Self::IS_DELETED_OFFSET + Self::IS_DELETED_SIZE;
pub const IS_DELETED_OFFSET: usize = 0;
pub const IS_DELETED_SIZE: usize = size_of::<bool>();
pub const DATA_SIZES_OFFSET: usize = Self::IS_DELETED_OFFSET + Self::IS_DELETED_SIZE;
fn size(number_of_columns: usize) -> usize {
pub fn size(number_of_columns: usize) -> usize {
let size_of_data_sizes: usize = number_of_columns*size_of::<usize>();
Self::IS_DELETED_SIZE + size_of_data_sizes
}
fn size_of_data(&self) -> usize{
pub fn size_of_data(&self) -> usize{
self.data_sizes.iter().sum()
}
}
@ -164,7 +156,7 @@ impl <T>SomethingSupportingLeq for Store<T>
}
}
const ROWS_FILE_NAME: &'static str = "rows";
pub const ROWS_FILE_NAME: &'static str = "rows";
impl <T>Store<T> {
// For debugging.
@ -289,13 +281,13 @@ impl StoreHeader {
}
// returns new count
fn increment_total_count(&mut self) -> usize {
pub fn increment_total_count(&mut self) -> usize {
self.total_count += 1;
self.total_count
}
// returns new count
fn increment_deleted_count(&mut self) -> usize {
pub fn increment_deleted_count(&mut self) -> usize {
self.deleted_count += 1;
self.deleted_count
}
@ -310,7 +302,7 @@ impl EntryHeader {
}
impl EntryHeaderWithDataSize {
fn decode(bytes: &mut [u8], number_of_columns: usize) -> Result<Self> {
pub fn decode(bytes: &mut [u8], number_of_columns: usize) -> Result<Self> {
let (is_deleted, _) =
decode::<bool>(&bytes)
.map_err(|e| Error::DecodeError(DecodeErrorKind::EntryIsDeleted, e))?;
@ -332,7 +324,7 @@ impl <T>Entry<T> {
}
// FORMAT: [EntryHeaderWithDataSize, ..sequence of data]
fn encode(&self) -> Result<Vec<u8>>
pub fn encode(&self) -> Result<Vec<u8>>
where T: Encode
{
let mut result: Vec<u8> = self.header.encode()?;
@ -345,7 +337,7 @@ impl <T>Entry<T> {
}
impl <T>EntryDetailed<T> {
fn decode(header: EntryHeaderWithDataSize, number_of_columns: usize, bytes: &[u8]) -> Result<Self>
pub fn decode(header: EntryHeaderWithDataSize, number_of_columns: usize, bytes: &[u8]) -> Result<Self>
where T: Decode
{
let data = decode_sequence::<T>(number_of_columns, bytes)
@ -405,7 +397,6 @@ impl <T>Cursor<T> {
Ok(result)
}
// TODO: make private
pub async fn seek_to(&mut self, file_position: FilePosition) -> Result<()> {
self.file.seek(SeekFrom::Start(file_position)).await?;
Ok(())
@ -425,7 +416,6 @@ impl <T>Cursor<T> {
self.seek_to(StoreHeader::SIZE as u64).await
}
// TODO: Make private
pub async fn current_file_position(&mut self) -> Result<FilePosition> {
let next_file_position: FilePosition = self.file.stream_position().await?;
Ok(next_file_position)