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restructure Poll to hold a Table and fd instead of a RefMut<dyn WasiFile>

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unfortunately, the borrow checker defeated me: changing the
RwSubscription file form a Ref to a RefMut turned into borrow checker
errors in the impl of the poll_oneoff trait method.

This implementation makes an end run by having Poll hold onto the table
and fd, and borrow the file at the site of use, rather than try to own
the RefMut. I have no idea why this convinces the borrow checker that
anything is different, but it does and I need to get this PR done and
I don't think comprimising on this internal abstraction is worth
fighting against
This commit is contained in:
Pat Hickey
2021-04-28 11:56:48 -07:00
parent 02581ddda0
commit b3e1ab4553
6 changed files with 72 additions and 70 deletions
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28
crates/wasi-common/src/snapshots/preview_0.rs
View File

@@ -1,4 +1,4 @@
use crate::file::{FileCaps, FileEntryExt, FileEntryMutExt, TableFileExt};
use crate::file::{FileCaps, FileEntryExt, TableFileExt};
use crate::sched::{
subscription::{RwEventFlags, SubscriptionResult},
Poll,
@@ -7,7 +7,6 @@ use crate::snapshots::preview_1::types as snapshot1_types;
use crate::snapshots::preview_1::wasi_snapshot_preview1::WasiSnapshotPreview1 as Snapshot1;
use crate::{Error, ErrorExt, WasiCtx};
use cap_std::time::Duration;
use std::collections::HashSet;
use std::convert::{TryFrom, TryInto};
use std::io::{IoSlice, IoSliceMut};
use std::ops::Deref;
@@ -779,8 +778,7 @@ impl wasi_unstable::WasiUnstable for WasiCtx {
}
let table = self.table();
let mut subscribed_fds = HashSet::new();
let mut poll = Poll::new();
let mut poll = Poll::new(&table);
let subs = subs.as_array(nsubscriptions);
for sub_elem in subs.iter() {
@@ -818,29 +816,11 @@ impl wasi_unstable::WasiUnstable for WasiCtx {
},
types::SubscriptionU::FdRead(readsub) => {
let fd = readsub.file_descriptor;
if subscribed_fds.contains(&fd) {
Err(Error::invalid_argument()
.context("Fd can be subscribed to at most once per poll_oneoff"))?;
} else {
subscribed_fds.insert(fd);
}
let file = table
.get_file_mut(u32::from(fd))?
.get_cap(FileCaps::POLL_READWRITE)?;
poll.subscribe_read(file, sub.userdata.into());
poll.subscribe_read(u32::from(fd), sub.userdata.into())?;
}
types::SubscriptionU::FdWrite(writesub) => {
let fd = writesub.file_descriptor;
if subscribed_fds.contains(&fd) {
Err(Error::invalid_argument()
.context("Fd can be subscribed to at most once per poll_oneoff"))?;
} else {
subscribed_fds.insert(fd);
}
let file = table
.get_file_mut(u32::from(fd))?
.get_cap(FileCaps::POLL_READWRITE)?;
poll.subscribe_write(file, sub.userdata.into());
poll.subscribe_write(u32::from(fd), sub.userdata.into())?;
}
}
}

26
crates/wasi-common/src/snapshots/preview_1.rs
View File

@@ -13,7 +13,6 @@ use crate::{
use anyhow::Context;
use cap_std::time::{Duration, SystemClock};
use std::cell::{Ref, RefMut};
use std::collections::HashSet;
use std::convert::{TryFrom, TryInto};
use std::io::{IoSlice, IoSliceMut};
use std::ops::{Deref, DerefMut};
@@ -971,8 +970,7 @@ impl wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
}
let table = self.table();
let mut subscribed_fds = HashSet::new();
let mut poll = Poll::new();
let mut poll = Poll::new(&table);
let subs = subs.as_array(nsubscriptions);
for sub_elem in subs.iter() {
@@ -1010,29 +1008,11 @@ impl wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
},
types::SubscriptionU::FdRead(readsub) => {
let fd = readsub.file_descriptor;
if subscribed_fds.contains(&fd) {
return Err(Error::invalid_argument()
.context("Fd can be subscribed to at most once per poll_oneoff"));
} else {
subscribed_fds.insert(fd);
}
let file = table
.get_file_mut(u32::from(fd))?
.get_cap(FileCaps::POLL_READWRITE)?;
poll.subscribe_read(file, sub.userdata.into());
poll.subscribe_read(u32::from(fd), sub.userdata.into())?;
}
types::SubscriptionU::FdWrite(writesub) => {
let fd = writesub.file_descriptor;
if subscribed_fds.contains(&fd) {
return Err(Error::invalid_argument()
.context("Fd can be subscribed to at most once per poll_oneoff"));
} else {
subscribed_fds.insert(fd);
}
let file = table
.get_file_mut(u32::from(fd))?
.get_cap(FileCaps::POLL_READWRITE)?;
poll.subscribe_write(file, sub.userdata.into());
poll.subscribe_write(u32::from(fd), sub.userdata.into())?;
}
}
}