feat(tvix/store/fuse): implement open explicitly

This moves from stateless I/O to actually dealing with file handles,
allowing the filesystem to keep reusing existing blobreaders, instead of
opening a new reader on every read() call.

Change-Id: I3fc35c071e4aee1021c8bbd58749d082b0abd188
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8834
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
This commit is contained in:
Florian Klink 2023-06-20 01:17:13 +02:00 committed by clbot
parent 22e7e7bc99
commit f5e291cf83

View file

@ -18,7 +18,7 @@ use crate::{
};
use fuser::{FileAttr, ReplyAttr, Request};
use nix_compat::store_path::StorePath;
use std::io::Read;
use std::io::{self, Read};
use std::sync::Arc;
use std::{collections::HashMap, time::Duration};
use tracing::{debug, info_span, warn};
@ -69,6 +69,11 @@ pub struct FUSE {
/// This keeps track of inodes and data alongside them.
inode_tracker: InodeTracker,
/// This holds all open file handles
file_handles: HashMap<u64, Box<dyn io::Read + Send>>,
next_file_handle: u64,
}
impl FUSE {
@ -84,6 +89,9 @@ impl FUSE {
store_paths: HashMap::default(),
inode_tracker: Default::default(),
file_handles: Default::default(),
next_file_handle: 1,
}
}
@ -356,21 +364,10 @@ impl fuser::Filesystem for FUSE {
}
}
/// TODO: implement open + close?
#[tracing::instrument(skip_all, fields(rq.inode = ino, rq.offset = offset, rq.size = size))]
fn read(
&mut self,
_req: &Request<'_>,
ino: u64,
_fh: u64,
offset: i64,
size: u32,
_flags: i32,
_lock_owner: Option<u64>,
reply: fuser::ReplyData,
) {
debug!("read");
#[tracing::instrument(skip_all, fields(rq.inode = ino))]
fn open(&mut self, _req: &Request<'_>, ino: u64, _flags: i32, reply: fuser::ReplyOpen) {
// get a new file handle
let fh = self.next_file_handle;
if ino == fuser::FUSE_ROOT_ID {
reply.error(libc::ENOSYS);
@ -397,6 +394,55 @@ impl fuser::Filesystem for FUSE {
reply.error(libc::EIO);
}
Ok(Some(blob_reader)) => {
self.file_handles.insert(fh, blob_reader);
reply.opened(fh, 0);
// TODO: this will overflow after 2**64 operations,
// which is fine for now.
// See https://cl.tvl.fyi/c/depot/+/8834/comment/a6684ce0_d72469d1
// for the discussion on alternatives.
self.next_file_handle += 1;
}
}
}
}
}
#[tracing::instrument(skip_all, fields(rq.inode = ino, fh = fh))]
fn release(
&mut self,
_req: &Request<'_>,
ino: u64,
fh: u64,
_flags: i32,
_lock_owner: Option<u64>,
_flush: bool,
reply: fuser::ReplyEmpty,
) {
// remove and get ownership on the blob reader
let blob_reader = self.file_handles.remove(&fh).unwrap();
// drop it, which will close it.
drop(blob_reader);
reply.ok();
}
#[tracing::instrument(skip_all, fields(rq.inode = ino, rq.offset = offset, rq.size = size))]
fn read(
&mut self,
_req: &Request<'_>,
ino: u64,
fh: u64,
offset: i64,
size: u32,
_flags: i32,
_lock_owner: Option<u64>,
reply: fuser::ReplyData,
) {
debug!("read");
let blob_reader = self.file_handles.get_mut(&fh).unwrap();
let data: std::io::Result<Vec<u8>> = blob_reader
.bytes()
// TODO: this is obviously terrible. blobreader should implement seek.
@ -412,10 +458,6 @@ impl fuser::Filesystem for FUSE {
Err(e) => reply.error(e.raw_os_error().unwrap()),
}
}
}
}
}
}
#[tracing::instrument(skip_all, fields(rq.inode = ino))]
fn readlink(&mut self, _req: &Request<'_>, ino: u64, reply: fuser::ReplyData) {