154 lines
3.6 KiB
Rust
154 lines
3.6 KiB
Rust
use anyhow::{anyhow, Result};
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use rio::{self, Completion, Rio};
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use std::alloc::{alloc, dealloc, Layout};
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use std::collections::HashMap;
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use std::fs::File;
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use std::fs::OpenOptions;
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use std::io;
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use std::io::{Read, Seek};
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use std::os::unix::fs::OpenOptionsExt;
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use std::path::Path;
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use std::sync::{Arc, Mutex};
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pub const BLOCK_SIZE: usize = 4096;
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const ALIGN: usize = 4096;
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// FIXME: introduce a cache
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// FIXME: use O_DIRECT
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#[derive(Debug)]
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pub struct Block {
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pub loc: u64,
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data: *mut u8,
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}
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impl Block {
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pub fn new(loc: u64) -> Block {
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let layout = Layout::from_size_align(BLOCK_SIZE, ALIGN).unwrap();
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let ptr = unsafe { alloc(layout) };
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assert!(!ptr.is_null(), "out of memory");
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Block { loc, data: ptr }
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}
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pub fn get_data<'a>(&self) -> &'a mut [u8] {
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unsafe { std::slice::from_raw_parts_mut::<'a>(self.data, BLOCK_SIZE) }
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}
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}
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impl Drop for Block {
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fn drop(&mut self) {
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let layout = Layout::from_size_align(BLOCK_SIZE, ALIGN).unwrap();
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unsafe {
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dealloc(self.data, layout);
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}
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}
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}
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//------------------------------------------
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pub trait IoEngine {
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fn get_nr_blocks(&self) -> u64;
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fn read(&mut self, block: &mut Block) -> Result<()>;
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fn read_many(&mut self, blocks: &mut Vec<Block>) -> Result<()>;
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}
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fn get_nr_blocks(path: &Path) -> io::Result<u64> {
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let metadata = std::fs::metadata(path)?;
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Ok(metadata.len() / (BLOCK_SIZE as u64))
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}
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//------------------------------------------
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pub struct SyncIoEngine {
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nr_blocks: u64,
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input: File,
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}
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impl SyncIoEngine {
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pub fn new(path: &Path) -> Result<SyncIoEngine> {
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let input = OpenOptions::new()
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.read(true)
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.write(false)
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.custom_flags(libc::O_DIRECT)
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.open(path)?;
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Ok(SyncIoEngine {
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nr_blocks: get_nr_blocks(path)?,
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input,
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})
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}
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}
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impl IoEngine for SyncIoEngine {
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fn get_nr_blocks(&self) -> u64 {
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self.nr_blocks
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}
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fn read(&mut self, b: &mut Block) -> Result<()> {
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self.input.seek(io::SeekFrom::Start(b.loc * BLOCK_SIZE as u64))?;
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self.input.read_exact(&mut b.get_data())?;
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Ok(())
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}
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fn read_many(&mut self, blocks: &mut Vec<Block>) -> Result<()> {
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for b in blocks {
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self.read(b);
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}
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Ok(())
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}
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}
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//------------------------------------------
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/*
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pub struct AsyncIoEngine {
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ring: Rio,
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nr_blocks: u64,
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input: File,
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}
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impl AsyncIoEngine {
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pub fn new(path: &Path) -> Result<IoEngine> {
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let input = OpenOptions::new()
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.read(true)
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.write(false)
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.custom_flags(libc::O_DIRECT)
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.open(path)?;
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let ring = rio::new()?;
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Ok(IoEngine {
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ring,
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nr_blocks: get_nr_blocks(path)?,
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input,
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})
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}
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pub fn read(&self, blocks: &mut Vec<Block>) -> Result<()> {
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// FIXME: using a bounce buffer as a hack, since b.get_data() will not have
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// a big enough lifetime.
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let mut bounce_buffer = vec![0; blocks.len() * BLOCK_SIZE];
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let mut completions = Vec::new();
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for n in 0..blocks.len() {
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let b = &blocks[n];
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let at = b.loc * BLOCK_SIZE as u64;
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let completion = self.ring.read_at(&self.input, &slice, at);
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completions.push(completion);
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}
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for c in completions {
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let n = c.wait()?;
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if n != BLOCK_SIZE {
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return Err(anyhow!("short read"));
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}
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}
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// copy out of the bounce buffer
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Ok(())
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}
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}
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*/
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