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SingleThreadPauseableExecutor.kt
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SingleThreadPauseableExecutor.kt
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/*
* Copyright 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dev.chrisbanes.accompanist.picasso
import java.util.concurrent.LinkedBlockingQueue
import java.util.concurrent.ThreadPoolExecutor
import java.util.concurrent.TimeUnit
import java.util.concurrent.locks.ReentrantLock
/**
* This is copied from the javadoc on [ThreadPoolExecutor].
*/
internal class SingleThreadPausableExecutor(paused: Boolean = false) : ThreadPoolExecutor(
1, 1, 0L, TimeUnit.MILLISECONDS, LinkedBlockingQueue()
) {
private var isPaused = paused
private val pauseLock = ReentrantLock()
private val unpaused = pauseLock.newCondition()
override fun beforeExecute(t: Thread, r: Runnable) {
super.beforeExecute(t, r)
pauseLock.lock()
try {
while (isPaused) unpaused.await()
} catch (ie: InterruptedException) {
t.interrupt()
} finally {
pauseLock.unlock()
}
}
fun pause() {
pauseLock.lock()
try {
isPaused = true
} finally {
pauseLock.unlock()
}
}
fun resume() {
pauseLock.lock()
try {
isPaused = false
unpaused.signalAll()
} finally {
pauseLock.unlock()
}
}
}