mirror of
https://chromium.googlesource.com/crosvm/crosvm
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0edf83a0b5
Add an executor, similar to `fd_executor`, except driven by io_uring instead of `PollContext`. This will allow for queueing actions instead of waiting for 'ready' from poll. This reduces the number of syscalls and increases the parallelism possible when doing IO. Change-Id: Ie2e69cb09ee3ab1086ef31d5ebd0169843a8228d Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2227083 Commit-Queue: Dylan Reid <dgreid@chromium.org> Tested-by: Dylan Reid <dgreid@chromium.org> Reviewed-by: Dylan Reid <dgreid@chromium.org>
48 lines
1.8 KiB
Rust
48 lines
1.8 KiB
Rust
// Copyright 2020 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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use std::rc::Rc;
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use std::sync::atomic::{AtomicBool, Ordering};
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use std::task::{RawWaker, RawWakerVTable};
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/// Wrapper around a u64 used as a token to uniquely identify a pending waker.
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#[derive(Clone, Debug, PartialEq, PartialOrd, Eq, Ord)]
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pub(crate) struct WakerToken(pub(crate) u64);
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// Boiler-plate for creating a waker with function pointers.
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// This waker sets the atomic bool it is passed to true.
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// The bool will be used by the executor to know which futures to poll
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// Convert the pointer back to the Rc it was created from and drop it.
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unsafe fn waker_drop(data_ptr: *const ()) {
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// from_raw, then drop
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let _rc_bool = Rc::<AtomicBool>::from_raw(data_ptr as *const _);
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}
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unsafe fn waker_wake(data_ptr: *const ()) {
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waker_wake_by_ref(data_ptr)
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}
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// Called when the bool should be set to true to wake the waker.
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unsafe fn waker_wake_by_ref(data_ptr: *const ()) {
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let bool_atomic_ptr = data_ptr as *const AtomicBool;
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let bool_atomic_ref = bool_atomic_ptr.as_ref().unwrap();
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bool_atomic_ref.store(true, Ordering::Relaxed);
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}
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// The data_ptr will be a pointer to an Rc<AtomicBool>.
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unsafe fn waker_clone(data_ptr: *const ()) -> RawWaker {
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let rc_bool = Rc::<AtomicBool>::from_raw(data_ptr as *const _);
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let new_ptr = rc_bool.clone();
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Rc::into_raw(rc_bool); // Don't decrement the ref count of the original, so back to raw.
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create_waker(Rc::into_raw(new_ptr) as *const _)
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}
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static WAKER_VTABLE: RawWakerVTable =
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RawWakerVTable::new(waker_clone, waker_wake, waker_wake_by_ref, waker_drop);
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/// To use safely, data_ptr must be from Rc<AtomicBool>::from_raw().
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pub unsafe fn create_waker(data_ptr: *const ()) -> RawWaker {
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RawWaker::new(data_ptr, &WAKER_VTABLE)
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}
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