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#![forbid(non_ascii_idents)]
#![deny(
macro_use_extern_crate,
missing_copy_implementations,
missing_debug_implementations,
rust_2018_idioms,
rust_2021_compatibility,
trivial_casts,
trivial_numeric_casts,
unused_extern_crates,
unused_import_braces,
unused_qualifications
)]
#![warn(
clippy::nursery,
clippy::pedantic,
clippy::mutex_atomic,
clippy::rc_buffer,
clippy::rc_mutex,
)]
#![allow(
clippy::cast_possible_truncation,
clippy::cast_possible_wrap,
clippy::cast_precision_loss,
clippy::cast_sign_loss,
clippy::missing_errors_doc,
clippy::missing_panics_doc,
clippy::must_use_candidate
)]
use std::cmp::min;
use std::collections::VecDeque;
use std::fs::{rename, File, OpenOptions};
use std::io;
use std::io::{Read, Seek, SeekFrom, Write};
use std::mem::ManuallyDrop;
use std::path::Path;
use bytes::{Buf, BufMut, BytesMut};
use snafu::{ensure, Snafu};
#[derive(Debug, Snafu)]
pub enum Error {
#[snafu(context(false))]
Io { source: std::io::Error },
#[snafu(display("too many elements"))]
TooManyElements {},
#[snafu(display("element too big"))]
ElementTooBig {},
#[snafu(display("corrupted file: {}", msg))]
CorruptedFile { msg: String },
#[snafu(display(
"unsupported version {}. supported versions is {} and legacy",
detected,
supported
))]
UnsupportedVersion { detected: u32, supported: u32 },
}
type Result<T, E = Error> = std::result::Result<T, E>;
#[derive(Debug)]
pub struct QueueFile {
inner: QueueFileInner,
versioned: bool,
header_len: u64,
elem_cnt: usize,
first: Element,
last: Element,
capacity: u64,
overwrite_on_remove: bool,
skip_write_header_on_add: bool,
write_buf: Vec<u8>,
cached_offsets: VecDeque<(usize, Element)>,
offset_cache_kind: Option<OffsetCacheKind>,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum OffsetCacheKind {
Linear { offset: usize },
Quadratic,
}
#[derive(Debug)]
struct QueueFileInner {
file: ManuallyDrop<File>,
file_len: u64,
expected_seek: u64,
last_seek: Option<u64>,
read_buffer_offset: Option<u64>,
read_buffer: Vec<u8>,
transfer_buf: Option<Box<[u8]>>,
sync_writes: bool,
}
impl Drop for QueueFile {
fn drop(&mut self) {
if self.skip_write_header_on_add {
let _ = self.sync_header();
}
unsafe {
ManuallyDrop::drop(&mut self.inner.file);
}
}
}
impl QueueFile {
const BLOCK_LENGTH: u64 = 4096;
const INITIAL_LENGTH: u64 = 4096;
const READ_BUFFER_SIZE: usize = 4096;
const VERSIONED_HEADER: u32 = 0x8000_0001;
const ZEROES: [u8; 4096] = [0; 4096];
fn init(path: &Path, force_legacy: bool, capacity: u64) -> Result<()> {
let tmp_path = path.with_extension(".tmp");
{
let mut file =
OpenOptions::new().read(true).write(true).create(true).open(&tmp_path)?;
file.set_len(capacity)?;
let mut buf = BytesMut::with_capacity(16);
if force_legacy {
buf.put_u32(capacity as u32);
} else {
buf.put_u32(Self::VERSIONED_HEADER);
buf.put_u64(capacity);
}
file.write_all(buf.as_ref())?;
}
rename(tmp_path, path)?;
Ok(())
}
pub fn with_capacity<P: AsRef<Path>>(path: P, capacity: u64) -> Result<Self> {
Self::open_internal(path, true, false, capacity)
}
pub fn open<P: AsRef<Path>>(path: P) -> Result<Self> {
Self::with_capacity(path, Self::INITIAL_LENGTH)
}
pub fn open_legacy<P: AsRef<Path>>(path: P) -> Result<Self> {
Self::open_internal(path, true, true, Self::INITIAL_LENGTH)
}
fn open_internal<P: AsRef<Path>>(
path: P, overwrite_on_remove: bool, force_legacy: bool, capacity: u64,
) -> Result<Self> {
if !path.as_ref().exists() {
Self::init(path.as_ref(), force_legacy, capacity)?;
}
let mut file = OpenOptions::new().read(true).write(true).open(path)?;
let mut buf = [0u8; 32];
let bytes_read = file.read(&mut buf)?;
ensure!(bytes_read >= 32, CorruptedFileSnafu { msg: "file too short" });
let versioned = !force_legacy && (buf[0] & 0x80) != 0;
let header_len: u64;
let file_len: u64;
let elem_cnt: usize;
let first_pos: u64;
let last_pos: u64;
let mut buf = BytesMut::from(&buf[..]);
if versioned {
header_len = 32;
let version = buf.get_u32() & 0x7FFF_FFFF;
ensure!(version == 1, UnsupportedVersionSnafu { detected: version, supported: 1u32 });
file_len = buf.get_u64();
elem_cnt = buf.get_u32() as usize;
first_pos = buf.get_u64();
last_pos = buf.get_u64();
ensure!(i64::try_from(file_len).is_ok(), CorruptedFileSnafu {
msg: "file length in header is greater than i64::MAX"
});
ensure!(i32::try_from(elem_cnt).is_ok(), CorruptedFileSnafu {
msg: "element count in header is greater than i32::MAX"
});
ensure!(i64::try_from(first_pos).is_ok(), CorruptedFileSnafu {
msg: "first element position in header is greater than i64::MAX"
});
ensure!(i64::try_from(last_pos).is_ok(), CorruptedFileSnafu {
msg: "last element position in header is greater than i64::MAX"
});
} else {
header_len = 16;
file_len = u64::from(buf.get_u32());
elem_cnt = buf.get_u32() as usize;
first_pos = u64::from(buf.get_u32());
last_pos = u64::from(buf.get_u32());
ensure!(i32::try_from(file_len).is_ok(), CorruptedFileSnafu {
msg: "file length in header is greater than i32::MAX"
});
ensure!(i32::try_from(elem_cnt).is_ok(), CorruptedFileSnafu {
msg: "element count in header is greater than i32::MAX"
});
ensure!(i32::try_from(first_pos).is_ok(), CorruptedFileSnafu {
msg: "first element position in header is greater than i32::MAX"
});
ensure!(i32::try_from(last_pos).is_ok(), CorruptedFileSnafu {
msg: "last element position in header is greater than i32::MAX"
});
}
let real_file_len = file.metadata()?.len();
ensure!(file_len <= real_file_len, CorruptedFileSnafu {
msg: format!(
"file is truncated. expected length was {file_len} but actual length is {real_file_len}"
)
});
ensure!(file_len >= header_len, CorruptedFileSnafu {
msg: format!("length stored in header ({file_len}) is invalid")
});
ensure!(first_pos <= file_len, CorruptedFileSnafu {
msg: format!("position of the first element ({first_pos}) is beyond the file")
});
ensure!(last_pos <= file_len, CorruptedFileSnafu {
msg: format!("position of the last element ({last_pos}) is beyond the file")
});
let mut queue_file = Self {
inner: QueueFileInner {
file: ManuallyDrop::new(file),
file_len,
expected_seek: 0,
last_seek: Some(32),
read_buffer_offset: None,
read_buffer: vec![0; Self::READ_BUFFER_SIZE],
transfer_buf: Some(
vec![0u8; QueueFileInner::TRANSFER_BUFFER_SIZE].into_boxed_slice(),
),
sync_writes: cfg!(not(test)),
},
versioned,
header_len,
elem_cnt,
first: Element::EMPTY,
last: Element::EMPTY,
capacity,
overwrite_on_remove,
skip_write_header_on_add: false,
write_buf: Vec::new(),
cached_offsets: VecDeque::new(),
offset_cache_kind: None,
};
if file_len < capacity {
queue_file.inner.sync_set_len(queue_file.capacity)?;
}
queue_file.first = queue_file.read_element(first_pos)?;
queue_file.last = queue_file.read_element(last_pos)?;
Ok(queue_file)
}
#[inline]
pub const fn overwrite_on_remove(&self) -> bool {
self.overwrite_on_remove
}
#[deprecated(since = "1.4.7", note = "Use `overwrite_on_remove` instead.")]
pub const fn get_overwrite_on_remove(&self) -> bool {
self.overwrite_on_remove()
}
#[inline]
pub fn set_overwrite_on_remove(&mut self, value: bool) {
self.overwrite_on_remove = value;
}
#[inline]
pub const fn sync_writes(&self) -> bool {
self.inner.sync_writes
}
#[deprecated(since = "1.4.7", note = "Use `sync_writes` instead.")]
pub const fn get_sync_writes(&self) -> bool {
self.sync_writes()
}
#[inline]
pub fn set_sync_writes(&mut self, value: bool) {
self.inner.sync_writes = value;
}
#[inline]
pub const fn skip_write_header_on_add(&self) -> bool {
self.skip_write_header_on_add
}
#[deprecated(since = "1.4.7", note = "Use `skip_write_header_on_add` instead.")]
pub const fn get_skip_write_header_on_add(&self) -> bool {
self.skip_write_header_on_add()
}
#[inline]
pub fn set_skip_write_header_on_add(&mut self, value: bool) {
self.skip_write_header_on_add = value;
}
pub fn set_read_buffer_size(&mut self, size: usize) {
if self.inner.read_buffer.len() < size {
self.inner.read_buffer_offset = None;
}
self.inner.read_buffer.resize(size, 0);
}
#[inline]
pub const fn cache_offset_policy(&self) -> Option<OffsetCacheKind> {
self.offset_cache_kind
}
#[deprecated(since = "1.4.7", note = "Use `cache_offset_policy` instead.")]
pub const fn get_cache_offset_policy(&self) -> Option<OffsetCacheKind> {
self.cache_offset_policy()
}
#[inline]
pub fn set_cache_offset_policy(&mut self, kind: impl Into<Option<OffsetCacheKind>>) {
self.offset_cache_kind = kind.into();
if self.offset_cache_kind.is_none() {
self.cached_offsets.clear();
}
}
#[inline]
pub const fn is_empty(&self) -> bool {
self.elem_cnt == 0
}
#[inline]
pub const fn size(&self) -> usize {
self.elem_cnt
}
pub fn sync_all(&mut self) -> Result<()> {
if self.skip_write_header_on_add {
self.sync_header()?;
}
Ok(self.inner.file.sync_all()?)
}
fn cache_last_offset_if_needed(&mut self, affected_items: usize) {
if self.elem_cnt == 0 {
return;
}
self.cache_elem_if_needed(self.elem_cnt - 1, self.last, affected_items);
}
fn cache_elem_if_needed(&mut self, index: usize, elem: Element, affected_items: usize) {
debug_assert!(index <= self.elem_cnt);
debug_assert!(index + 1 >= affected_items);
let need_to_cache = self.offset_cache_kind.map_or(false, |kind| match kind {
OffsetCacheKind::Linear { offset } => {
let last_cached_index = self.cached_offsets.back().map_or(0, |(idx, _)| *idx);
index.saturating_sub(last_cached_index) >= offset
}
OffsetCacheKind::Quadratic => {
let x = (index as f64).sqrt() as usize;
x > 1 && (index + 1 - affected_items..=index).contains(&(x * x))
}
});
if need_to_cache {
if let Some((last_cached_index, last_cached_elem)) = self.cached_offsets.back() {
if *last_cached_index >= index {
if *last_cached_index == index {
debug_assert_eq!(last_cached_elem.pos, elem.pos);
debug_assert_eq!(last_cached_elem.len, elem.len);
}
return;
}
}
self.cached_offsets.push_back((index, elem));
}
}
#[inline]
fn cached_index_up_to(&self, i: usize) -> Option<usize> {
self.cached_offsets
.binary_search_by(|(idx, _)| idx.cmp(&i))
.map_or_else(|i| i.checked_sub(1), Some)
}
pub fn add_n(
&mut self, elems: impl IntoIterator<Item = impl AsRef<[u8]>> + Clone,
) -> Result<()> {
let (count, total_len) = elems
.clone()
.into_iter()
.fold((0, 0), |(c, l), elem| (c + 1, l + Element::HEADER_LENGTH + elem.as_ref().len()));
if count == 0 {
return Ok(());
}
ensure!(self.elem_cnt + count < i32::max_value() as usize, TooManyElementsSnafu {});
self.expand_if_necessary(total_len as u64)?;
let was_empty = self.is_empty();
let mut pos = if was_empty {
self.header_len
} else {
self.wrap_pos(self.last.pos + Element::HEADER_LENGTH as u64 + self.last.len as u64)
};
let mut first_added = None;
let mut last_added = None;
self.write_buf.clear();
for elem in elems {
let elem = elem.as_ref();
let len = elem.len();
if first_added.is_none() {
first_added = Some(Element::new(pos, len)?);
}
last_added = Some(Element::new(pos, len)?);
self.write_buf.extend(&(len as u32).to_be_bytes());
self.write_buf.extend(elem);
pos = self.wrap_pos(pos + Element::HEADER_LENGTH as u64 + len as u64);
}
let first_added = first_added.unwrap();
self.ring_write_buf(first_added.pos)?;
if was_empty {
self.first = first_added;
}
self.last = last_added.unwrap();
self.write_header(self.file_len(), self.elem_cnt + count, self.first.pos, self.last.pos)?;
self.elem_cnt += count;
self.cache_last_offset_if_needed(count);
Ok(())
}
#[inline]
pub fn add(&mut self, buf: &[u8]) -> Result<()> {
self.add_n(std::iter::once(buf))
}
pub fn peek(&mut self) -> Result<Option<Box<[u8]>>> {
if self.is_empty() {
Ok(None)
} else {
let len = self.first.len;
let mut data = vec![0; len].into_boxed_slice();
self.ring_read(self.first.pos + Element::HEADER_LENGTH as u64, &mut data)?;
Ok(Some(data))
}
}
#[inline]
pub fn remove(&mut self) -> Result<()> {
self.remove_n(1)
}
pub fn remove_n(&mut self, n: usize) -> Result<()> {
if n == 0 || self.is_empty() {
return Ok(());
}
if n >= self.elem_cnt {
return self.clear();
}
debug_assert!(
self.cached_offsets
.iter()
.zip(self.cached_offsets.iter().skip(1))
.all(|(a, b)| a.0 < b.0),
"{:?}",
self.cached_offsets
);
let erase_start_pos = self.first.pos;
let mut erase_total_len = 0usize;
let mut new_first_pos = self.first.pos;
let mut new_first_len = self.first.len;
let cached_index = self.cached_index_up_to(n - 1);
let to_remove = if let Some(i) = cached_index {
let (index, elem) = self.cached_offsets[i];
if let Some(index) = index.checked_sub(1) {
erase_total_len += Element::HEADER_LENGTH * index;
erase_total_len += (elem.pos
+ if self.first.pos < elem.pos {
0
} else {
self.file_len() - self.first.pos - self.header_len
}) as usize;
}
new_first_pos = elem.pos;
new_first_len = elem.len;
n - index
} else {
n
};
for _ in 0..to_remove {
erase_total_len += Element::HEADER_LENGTH + new_first_len;
new_first_pos =
self.wrap_pos(new_first_pos + Element::HEADER_LENGTH as u64 + new_first_len as u64);
let mut buf: [u8; 4] = [0; 4];
self.ring_read(new_first_pos, &mut buf)?;
new_first_len = u32::from_be_bytes(buf) as usize;
}
self.write_header(self.file_len(), self.elem_cnt - n, new_first_pos, self.last.pos)?;
self.elem_cnt -= n;
self.first = Element::new(new_first_pos, new_first_len)?;
if let Some(cached_index) = cached_index {
self.cached_offsets.drain(..=cached_index);
}
self.cached_offsets.iter_mut().for_each(|(i, _)| *i -= n);
if self.overwrite_on_remove {
self.ring_erase(erase_start_pos, erase_total_len)?;
}
Ok(())
}
pub fn clear(&mut self) -> Result<()> {
self.write_header(self.capacity, 0, 0, 0)?;
if self.overwrite_on_remove {
self.inner.seek(self.header_len);
let first_block = self.capacity.min(Self::BLOCK_LENGTH) - self.header_len;
self.inner.write(&Self::ZEROES[..first_block as usize])?;
if let Some(left) = self.capacity.checked_sub(Self::BLOCK_LENGTH) {
for _ in 0..left / Self::BLOCK_LENGTH {
self.inner.write(&Self::ZEROES)?;
}
let tail = left % Self::BLOCK_LENGTH;
if tail != 0 {
self.inner.write(&Self::ZEROES[..tail as usize])?;
}
}
}
self.cached_offsets.clear();
self.elem_cnt = 0;
self.first = Element::EMPTY;
self.last = Element::EMPTY;
if self.file_len() > self.capacity {
self.inner.sync_set_len(self.capacity)?;
}
Ok(())
}
pub fn iter(&mut self) -> Iter<'_> {
let pos = self.first.pos;
Iter {
buffer: std::mem::take(&mut self.write_buf),
queue_file: self,
next_elem_index: 0,
next_elem_pos: pos,
}
}
#[inline]
pub const fn file_len(&self) -> u64 {
self.inner.file_len
}
#[inline]
pub const fn used_bytes(&self) -> u64 {
if self.elem_cnt == 0 {
self.header_len
} else if self.last.pos >= self.first.pos {
(self.last.pos - self.first.pos)
+ Element::HEADER_LENGTH as u64
+ self.last.len as u64
+ self.header_len
} else {
self.last.pos + Element::HEADER_LENGTH as u64 + self.last.len as u64 + self.file_len()
- self.first.pos
}
}
pub fn into_inner_file(mut self) -> File {
if self.skip_write_header_on_add {
let _ = self.sync_header();
}
let file = unsafe { ManuallyDrop::take(&mut self.inner.file) };
std::mem::forget(self);
file
}
#[inline]
const fn remaining_bytes(&self) -> u64 {
self.file_len() - self.used_bytes()
}
fn sync_header(&mut self) -> Result<()> {
self.write_header(self.file_len(), self.size(), self.first.pos, self.last.pos)
}
fn write_header(
&mut self, file_len: u64, elem_cnt: usize, first_pos: u64, last_pos: u64,
) -> Result<()> {
let mut header = [0; 32];
let mut header_buf = &mut header[..];
if self.versioned {
ensure!(i64::try_from(file_len).is_ok(), CorruptedFileSnafu {
msg: "file length in header will exceed i64::MAX"
});
ensure!(i32::try_from(elem_cnt).is_ok(), CorruptedFileSnafu {
msg: "element count in header will exceed i32::MAX"
});
ensure!(i64::try_from(first_pos).is_ok(), CorruptedFileSnafu {
msg: "first element position in header will exceed i64::MAX"
});
ensure!(i64::try_from(last_pos).is_ok(), CorruptedFileSnafu {
msg: "last element position in header will exceed i64::MAX"
});
header_buf.put_u32(Self::VERSIONED_HEADER);
header_buf.put_u64(file_len);
header_buf.put_i32(elem_cnt as i32);
header_buf.put_u64(first_pos);
header_buf.put_u64(last_pos);
} else {
ensure!(i32::try_from(file_len).is_ok(), CorruptedFileSnafu {
msg: "file length in header will exceed i32::MAX"
});
ensure!(i32::try_from(elem_cnt).is_ok(), CorruptedFileSnafu {
msg: "element count in header will exceed i32::MAX"
});
ensure!(i32::try_from(first_pos).is_ok(), CorruptedFileSnafu {
msg: "first element position in header will exceed i32::MAX"
});
ensure!(i32::try_from(last_pos).is_ok(), CorruptedFileSnafu {
msg: "last element position in header will exceed i32::MAX"
});
header_buf.put_i32(file_len as i32);
header_buf.put_i32(elem_cnt as i32);
header_buf.put_i32(first_pos as i32);
header_buf.put_i32(last_pos as i32);
}
self.inner.seek(0);
self.inner.write(&header.as_ref()[..self.header_len as usize])
}
fn read_element(&mut self, pos: u64) -> Result<Element> {
if pos == 0 {
Ok(Element::EMPTY)
} else {
let mut buf: [u8; 4] = [0; Element::HEADER_LENGTH];
self.ring_read(pos, &mut buf)?;
Element::new(pos, u32::from_be_bytes(buf) as usize)
}
}
#[inline]
const fn wrap_pos(&self, pos: u64) -> u64 {
if pos < self.file_len() { pos } else { self.header_len + pos - self.file_len() }
}
fn ring_write_buf(&mut self, pos: u64) -> Result<()> {
let pos = self.wrap_pos(pos);
if pos + self.write_buf.len() as u64 <= self.file_len() {
self.inner.seek(pos);
self.inner.write(&self.write_buf)
} else {
let before_eof = (self.file_len() - pos) as usize;
self.inner.seek(pos);
self.inner.write(&self.write_buf[..before_eof])?;
self.inner.seek(self.header_len);
self.inner.write(&self.write_buf[before_eof..])
}
}
fn ring_erase(&mut self, pos: u64, n: usize) -> Result<()> {
let mut pos = pos;
let mut len = n;
self.write_buf.clear();
self.write_buf.extend(Self::ZEROES);
while len > 0 {
let chunk_len = min(len, Self::ZEROES.len());
self.write_buf.truncate(chunk_len);
self.ring_write_buf(pos)?;
len -= chunk_len;
pos += chunk_len as u64;
}
Ok(())
}
fn ring_read(&mut self, pos: u64, buf: &mut [u8]) -> io::Result<()> {
let pos = self.wrap_pos(pos);
if pos + buf.len() as u64 <= self.file_len() {
self.inner.seek(pos);
self.inner.read(buf)
} else {
let before_eof = (self.file_len() - pos) as usize;
self.inner.seek(pos);
self.inner.read(&mut buf[..before_eof])?;
self.inner.seek(self.header_len);
self.inner.read(&mut buf[before_eof..])
}
}
fn expand_if_necessary(&mut self, data_len: u64) -> Result<()> {
let mut rem_bytes = self.remaining_bytes();
if rem_bytes >= data_len {
return Ok(());
}
let orig_file_len = self.file_len();
let mut prev_len = orig_file_len;
let mut new_len = prev_len;
while rem_bytes < data_len {
rem_bytes += prev_len;
new_len = prev_len << 1;
prev_len = new_len;
}
let bytes_used_before = self.used_bytes();
let end_of_last_elem =
self.wrap_pos(self.last.pos + Element::HEADER_LENGTH as u64 + self.last.len as u64);
self.inner.sync_set_len(new_len)?;
let mut count = 0u64;
if end_of_last_elem <= self.first.pos {
count = end_of_last_elem - self.header_len;
self.inner.transfer(self.header_len, orig_file_len, count)?;
}
if self.last.pos < self.first.pos {
let new_last_pos = orig_file_len + self.last.pos - self.header_len;
self.last = Element::new(new_last_pos, self.last.len)?;
}
self.cached_offsets.clear();
if self.overwrite_on_remove {
self.ring_erase(self.header_len, count as usize)?;
}
let bytes_used_after = self.used_bytes();
debug_assert_eq!(bytes_used_before, bytes_used_after);
Ok(())
}
}
impl QueueFileInner {
const TRANSFER_BUFFER_SIZE: usize = 128 * 1024;
#[inline]
fn seek(&mut self, pos: u64) -> u64 {
self.expected_seek = pos;
pos
}
fn real_seek(&mut self) -> io::Result<u64> {
if Some(self.expected_seek) == self.last_seek {
return Ok(self.expected_seek);
}
let res = self.file.seek(SeekFrom::Start(self.expected_seek));
self.last_seek = res.as_ref().ok().copied();
res
}
fn read(&mut self, buf: &mut [u8]) -> io::Result<()> {
if buf.is_empty() {
return Ok(());
}
let size = buf.len();
let not_enough_data = if let Some(left) = self.read_buffer.len().checked_sub(size) {
self.read_buffer_offset
.and_then(|o| self.expected_seek.checked_sub(o))
.and_then(|skip| left.checked_sub(skip as usize))
.is_none()
} else {
self.read_buffer.resize(size, 0);
true
};
if not_enough_data {
use std::io::{Error, ErrorKind};
self.real_seek()?;
let mut read = 0;
let mut res = Ok(());
while !buf.is_empty() {
match self.file.read(&mut self.read_buffer[read..]) {
Ok(0) => break,
Ok(n) => read += n,
Err(ref e) if e.kind() == ErrorKind::Interrupted => {}
Err(e) => {
res = Err(e);
break;
}
}
}
if res.is_ok() && read < size {
res = Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
}
if let Err(err) = res {
self.read_buffer_offset = None;
self.last_seek = None;
return Err(err);
}
self.read_buffer_offset = Some(self.expected_seek);
if let Some(seek) = &mut self.last_seek {
*seek += read as u64;
}
}
let start = (self.expected_seek - self.read_buffer_offset.unwrap()) as usize;
buf.copy_from_slice(&self.read_buffer[start..start + size]);
Ok(())
}
fn write(&mut self, buf: &[u8]) -> Result<()> {
self.real_seek()?;
self.file.write_all(buf)?;
if let Some(seek) = &mut self.last_seek {
*seek += buf.len() as u64;
}
if let Some(read_buffer_offset) = self.read_buffer_offset {
let write_size_u64 = buf.len() as u64;
let read_buffer_end_offset = read_buffer_offset + self.read_buffer.len() as u64;
let read_buffered = read_buffer_offset..read_buffer_end_offset;
let has_start = read_buffered.contains(&self.expected_seek);
let buf_end = self.expected_seek + write_size_u64;
let has_end = read_buffered.contains(&buf_end);
match (has_start, has_end) {
(true, true) => {
let start = (self.expected_seek - read_buffer_offset) as usize;
self.read_buffer[start..start + buf.len()].copy_from_slice(buf);
}
(false, true) => {
let need_to_skip = (read_buffer_offset - self.expected_seek) as usize;
let need_to_copy = buf.len() - need_to_skip;
self.read_buffer[..need_to_copy].copy_from_slice(&buf[need_to_skip..]);
}
(true, false) => {
let need_to_skip = (self.expected_seek - read_buffer_offset) as usize;
let need_to_copy = self.read_buffer.len() - need_to_skip;
self.read_buffer[need_to_skip..need_to_skip + need_to_copy]
.copy_from_slice(&buf[..need_to_copy]);
}
(false, false)
if (self.expected_seek + 1..buf_end).contains(&read_buffer_offset) =>
{
let need_to_skip = (read_buffer_offset - self.expected_seek) as usize;
let need_to_copy = self.read_buffer.len();
self.read_buffer[..]
.copy_from_slice(&buf[need_to_skip..need_to_skip + need_to_copy]);
}
(false, false) => {}
}
}
if self.sync_writes {
self.file.sync_data()?;
}
Ok(())
}
fn transfer_inner(
&mut self, buf: &mut [u8], mut read_pos: u64, mut write_pos: u64, count: u64,
) -> Result<()> {
debug_assert!(read_pos < self.file_len);
debug_assert!(write_pos <= self.file_len);
debug_assert!(count < self.file_len);
debug_assert!(i64::try_from(count).is_ok());
let mut bytes_left = count as i64;
while bytes_left > 0 {
self.seek(read_pos);
let bytes_to_read = min(bytes_left as usize, Self::TRANSFER_BUFFER_SIZE);
self.read(&mut buf[..bytes_to_read])?;
self.seek(write_pos);
self.write(&buf[..bytes_to_read])?;
read_pos += bytes_to_read as u64;
write_pos += bytes_to_read as u64;
bytes_left -= bytes_to_read as i64;
}
if self.sync_writes {
self.file.sync_data()?;
}
Ok(())
}
fn transfer(&mut self, read_pos: u64, write_pos: u64, count: u64) -> Result<()> {
let mut buf = self.transfer_buf.take().unwrap();
let res = self.transfer_inner(&mut buf, read_pos, write_pos, count);
self.transfer_buf = Some(buf);
res
}
fn sync_set_len(&mut self, new_len: u64) -> io::Result<()> {
self.file.set_len(new_len)?;
self.file_len = new_len;
self.file.sync_all()
}
}
#[derive(Copy, Clone, Debug)]
struct Element {
pos: u64,
len: usize,
}
impl Element {
const EMPTY: Self = Self { pos: 0, len: 0 };
const HEADER_LENGTH: usize = 4;
#[inline]
fn new(pos: u64, len: usize) -> Result<Self> {
ensure!(i64::try_from(pos).is_ok(), CorruptedFileSnafu {
msg: "element position must be less or equal to i64::MAX"
});
ensure!(i32::try_from(len).is_ok(), ElementTooBigSnafu);
Ok(Self { pos, len })
}
}
#[derive(Debug)]
pub struct Iter<'a> {
queue_file: &'a mut QueueFile,
buffer: Vec<u8>,
next_elem_index: usize,
next_elem_pos: u64,
}
impl<'a> Iterator for Iter<'a> {
type Item = Box<[u8]>;
fn next(&mut self) -> Option<Self::Item> {
let buffer = self.borrowed_next()?;
Some(buffer.to_vec().into_boxed_slice())
}
fn size_hint(&self) -> (usize, Option<usize>) {
let elems_left = self.queue_file.elem_cnt - self.next_elem_index;
(elems_left, Some(elems_left))
}
fn nth(&mut self, n: usize) -> Option<Self::Item> {
if self.queue_file.elem_cnt - self.next_elem_index < n {
self.next_elem_index = self.queue_file.elem_cnt;
return None;
}
let left = if let Some(i) = self.queue_file.cached_index_up_to(n) {
let (index, elem) = self.queue_file.cached_offsets[i];
if index > self.next_elem_index {
self.next_elem_index = index;
self.next_elem_pos = elem.pos;
}
n - self.next_elem_index
} else {
n
};
for _ in 0..left {
self.borrowed_next();
}
self.next()
}
}
impl Iter<'_> {
pub fn borrowed_next(&mut self) -> Option<&[u8]> {
if self.next_elem_index >= self.queue_file.elem_cnt {
return None;
}
let current = self.queue_file.read_element(self.next_elem_pos).ok()?;
self.next_elem_pos = self.queue_file.wrap_pos(current.pos + Element::HEADER_LENGTH as u64);
if current.len > self.buffer.len() {
self.buffer.resize(current.len, 0);
}
self.queue_file.ring_read(self.next_elem_pos, &mut self.buffer[..current.len]).ok()?;
self.next_elem_pos = self
.queue_file
.wrap_pos(current.pos + Element::HEADER_LENGTH as u64 + current.len as u64);
self.queue_file.cache_elem_if_needed(self.next_elem_index, current, 1);
self.next_elem_index += 1;
Some(&self.buffer[..current.len])
}
}
impl Drop for Iter<'_> {
fn drop(&mut self) {
self.queue_file.write_buf = std::mem::take(&mut self.buffer);
}
}