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Support "sleep" forms of poll_oneoff. #2753

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merged 3 commits into from
Mar 22, 2021
Merged

Support "sleep" forms of poll_oneoff. #2753

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c62c9d1
Support "sleep" forms of `poll_oneoff`.
sunfishcode Mar 22, 2021
e4d6d31
Arrange for the new test to be called.
sunfishcode Mar 22, 2021
4ecb367
Add a `sleep` function to the `WasiSched` trait.
sunfishcode Mar 22, 2021
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42 changes: 41 additions & 1 deletion crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,10 @@ unsafe fn test_empty_poll() {
}

unsafe fn test_timeout() {
let timeout = 5_000_000u64; // 5 milliseconds
let clock = wasi::SubscriptionClock {
id: wasi::CLOCKID_MONOTONIC,
timeout: 5_000_000u64, // 5 milliseconds
timeout,
precision: 0,
flags: 0,
};
Expand All @@ -39,7 +40,9 @@ unsafe fn test_timeout() {
u: wasi::SubscriptionUU { clock },
},
}];
let before = wasi::clock_time_get(wasi::CLOCKID_MONOTONIC, 0).unwrap();
let out = poll_oneoff_impl(&r#in).unwrap();
let after = wasi::clock_time_get(wasi::CLOCKID_MONOTONIC, 0).unwrap();
assert_eq!(out.len(), 1, "should return 1 event");
let event = &out[0];
assert_errno!(event.error, wasi::ERRNO_SUCCESS);
Expand All @@ -52,6 +55,42 @@ unsafe fn test_timeout() {
event.userdata, CLOCK_ID,
"the event.userdata should contain clock_id specified by the user"
);
assert!(after - before >= timeout, "poll_oneoff should sleep for the specified interval");
}

// Like test_timeout, but uses `CLOCKID_REALTIME`, as WASI libc's sleep
// functions do.
unsafe fn test_sleep() {
let timeout = 5_000_000u64; // 5 milliseconds
let clock = wasi::SubscriptionClock {
id: wasi::CLOCKID_REALTIME,
timeout,
precision: 0,
flags: 0,
};
let r#in = [wasi::Subscription {
userdata: CLOCK_ID,
u: wasi::SubscriptionU {
tag: wasi::EVENTTYPE_CLOCK,
u: wasi::SubscriptionUU { clock },
},
}];
let before = wasi::clock_time_get(wasi::CLOCKID_MONOTONIC, 0).unwrap();
let out = poll_oneoff_impl(&r#in).unwrap();
let after = wasi::clock_time_get(wasi::CLOCKID_MONOTONIC, 0).unwrap();
assert_eq!(out.len(), 1, "should return 1 event");
let event = &out[0];
assert_errno!(event.error, wasi::ERRNO_SUCCESS);
assert_eq!(
event.r#type,
wasi::EVENTTYPE_CLOCK,
"the event.type should equal clock"
);
assert_eq!(
event.userdata, CLOCK_ID,
"the event.userdata should contain clock_id specified by the user"
);
assert!(after - before >= timeout, "poll_oneoff should sleep for the specified interval");
}

unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
Expand Down Expand Up @@ -156,6 +195,7 @@ unsafe fn test_fd_readwrite_invalid_fd() {

unsafe fn test_poll_oneoff(dir_fd: wasi::Fd) {
test_timeout();
test_sleep();
test_empty_poll();
test_fd_readwrite_valid_fd(dir_fd);
test_fd_readwrite_invalid_fd();
Expand Down
3 changes: 3 additions & 0 deletions crates/wasi-common/cap-std-sync/src/sched/unix.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,9 @@ impl WasiSched for SyncSched {
std::thread::yield_now();
Ok(())
}
fn sleep(&self, duration: Duration) {
std::thread::sleep(duration)
}
}

fn wasi_file_raw_fd(f: &dyn WasiFile) -> Option<RawFd> {
Expand Down
3 changes: 3 additions & 0 deletions crates/wasi-common/cap-std-sync/src/sched/windows.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,9 @@ impl WasiSched for SyncSched {
thread::yield_now();
Ok(())
}
fn sleep(&self, duration: Duration) {
std::thread::sleep(duration)
}
}

fn wasi_file_raw_handle(f: &dyn WasiFile) -> Option<RawHandle> {
Expand Down
1 change: 1 addition & 0 deletions crates/wasi-common/src/sched.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ use subscription::{MonotonicClockSubscription, RwSubscription, Subscription, Sub
pub trait WasiSched {
fn poll_oneoff(&self, poll: &Poll) -> Result<(), Error>;
fn sched_yield(&self) -> Result<(), Error>;
fn sleep(&self, duration: Duration);
}

pub struct Userdata(u64);
Expand Down
24 changes: 24 additions & 0 deletions crates/wasi-common/src/snapshots/preview_0.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -738,6 +738,30 @@ impl<'a> wasi_unstable::WasiUnstable for WasiCtx {
return Err(Error::invalid_argument().context("nsubscriptions must be nonzero"));
}

// Special-case a `poll_oneoff` which is just sleeping on a single
// relative timer event, such as what WASI libc uses to implement sleep
// functions. This supports all clock IDs, because POSIX says that
// `clock_settime` doesn't effect relative sleeps.
if nsubscriptions == 1 {
let sub = subs.read()?;
if let types::SubscriptionU::Clock(clocksub) = sub.u {
if !clocksub
.flags
.contains(types::Subclockflags::SUBSCRIPTION_CLOCK_ABSTIME)
{
self.sched.sleep(Duration::from_nanos(clocksub.timeout));

events.write(types::Event {
userdata: sub.userdata,
error: types::Errno::Success,
type_: types::Eventtype::Clock,
fd_readwrite: fd_readwrite_empty(),
})?;
return Ok(1);
}
}
}

let table = self.table();
let mut poll = Poll::new();

Expand Down
24 changes: 24 additions & 0 deletions crates/wasi-common/src/snapshots/preview_1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -909,6 +909,30 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
return Err(Error::invalid_argument().context("nsubscriptions must be nonzero"));
}

// Special-case a `poll_oneoff` which is just sleeping on a single
// relative timer event, such as what WASI libc uses to implement sleep
// functions. This supports all clock IDs, because POSIX says that
// `clock_settime` doesn't effect relative sleeps.
if nsubscriptions == 1 {
let sub = subs.read()?;
if let types::SubscriptionU::Clock(clocksub) = sub.u {
if !clocksub
.flags
.contains(types::Subclockflags::SUBSCRIPTION_CLOCK_ABSTIME)
{
self.sched.sleep(Duration::from_nanos(clocksub.timeout));

events.write(types::Event {
userdata: sub.userdata,
error: types::Errno::Success,
type_: types::Eventtype::Clock,
fd_readwrite: fd_readwrite_empty(),
})?;
return Ok(1);
}
}
}

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This special case is a good idea, but i'd like for the thread::sleep call to instead be dispatched into self.sched.sleep so that wasi-common consumers can control that implementation by either using the default wasi-cap-std-sync impls or creating their own.

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Sounds good; I've now added a sleep function to WasiSched and added impls for it.

let table = self.table();
let mut poll = Poll::new();

Expand Down