use std::ops::Range;
use super::CachedSlice;
use crate::common::ext::aligned_vec::ACow;
use crate::common::generic_consts::{AccessPattern, Sequential};
use crate::common::universal_io::{ReadPipeline, UioResult, UniversalIoError, UserData};
pub struct DiskCacheReadPipeline<'file, U> {
result: Option<(U, ACow<'file>)>,
}
impl<'file, U> ReadPipeline<'file, U> for DiskCacheReadPipeline<'file, U>
where
U: UserData,
{
type File = CachedSlice;
fn new() -> UioResult<Self> {
Ok(Self { result: None })
}
fn can_schedule(&mut self) -> bool {
self.result.is_none()
}
fn schedule<P>(
&mut self,
user_data: U,
file: &'file CachedSlice,
range: Range<u64>,
align: usize,
) -> UioResult<()>
where
P: AccessPattern,
{
if self.result.is_some() {
return Err(UniversalIoError::QueueIsFull);
}
let byte_range = range.start as usize..range.end as usize;
self.result = Some((user_data, file.get_range_bytes(byte_range, align)?));
Ok(())
}
fn schedule_whole(
&mut self,
user_data: U,
file: &'file Self::File,
from: u64,
) -> UioResult<()> {
let eof = file.len::<u8>() as u64;
self.schedule::<Sequential>(user_data, file, from..eof, 1)
}
fn wait(&mut self) -> UioResult<Option<(U, ACow<'file>)>> {
Ok(self.result.take())
}
}