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47 lines
1.5 KiB
47 lines
1.5 KiB
// Copyright 2021, The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//! Synchronisation utilities.
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use std::sync::{Arc, Condvar, Mutex};
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/// A flag which one thread can use to notify other threads when a condition becomes true. This is
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/// something like a single-use binary semaphore.
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#[derive(Clone, Debug)]
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pub struct AtomicFlag {
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state: Arc<(Mutex<bool>, Condvar)>,
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}
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impl Default for AtomicFlag {
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#[allow(clippy::mutex_atomic)]
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fn default() -> Self {
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Self { state: Arc::new((Mutex::new(false), Condvar::new())) }
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}
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}
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#[allow(clippy::mutex_atomic)]
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impl AtomicFlag {
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/// Wait until the flag is set.
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pub fn wait(&self) {
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let _flag = self.state.1.wait_while(self.state.0.lock().unwrap(), |flag| !*flag).unwrap();
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}
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/// Set the flag, and notify all waiting threads.
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pub fn raise(&self) {
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let mut flag = self.state.0.lock().unwrap();
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*flag = true;
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self.state.1.notify_all();
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}
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}
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