/*
* Copyright 2023 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
*
* http://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 androidx.camera.impl.utils.futures
import androidx.camera.impl.utils.Logger
import androidx.core.util.Preconditions
import com.google.common.util.concurrent.ListenableFuture
import java.util.concurrent.Delayed
import java.util.concurrent.ExecutionException
import java.util.concurrent.Executor
import java.util.concurrent.ScheduledFuture
import java.util.concurrent.TimeUnit
/**
* An implementation of [ListenableFuture] which immediately contains a result.
*
*
* This implementation is based off of the Guava ImmediateSuccessfulFuture class.
* @param <V> The type of the value stored in the future.
</V> */
internal abstract class ImmediateFuture<V> : ListenableFuture<V> {
override fun addListener(listener: Runnable, executor: Executor) {
Preconditions.checkNotNull(listener)
Preconditions.checkNotNull(executor)
try {
executor.execute(listener)
} catch (e: RuntimeException) {
// ListenableFuture does not throw runtime exceptions, so swallow the exception and
// log it here.
Logger.e(
TAG, "Experienced RuntimeException while attempting to notify " +
listener + " on Executor " + executor, e
)
}
}
override fun cancel(mayInterruptIfRunning: Boolean): Boolean {
return false
}
override fun isCancelled(): Boolean {
return false
}
override fun isDone(): Boolean {
return true
}
@Throws(ExecutionException::class)
abstract override fun get(): V?
@Throws(ExecutionException::class)
override fun get(timeout: Long, unit: TimeUnit): V? {
Preconditions.checkNotNull(unit)
return get()
}
internal class ImmediateSuccessfulFuture<V>(private val mValue: V?) : ImmediateFuture<V>() {
override fun get(): V? {
return mValue
}
override fun toString(): String {
// Behaviour analogous to AbstractResolvableFuture#toString().
return super.toString() + "[status=SUCCESS, result=[" + mValue + "]]"
}
}
internal open class ImmediateFailedFuture<V>(private val mCause: Throwable) :
ImmediateFuture<V>() {
@Throws(ExecutionException::class)
override fun get(): V? {
throw ExecutionException(mCause)
}
override fun toString(): String {
// Behaviour analogous to AbstractResolvableFuture#toString().
return super.toString() + "[status=FAILURE, cause=[" + mCause + "]]"
}
}
internal class ImmediateFailedScheduledFuture<V>(cause: Throwable) :
ImmediateFailedFuture<V>(cause), ScheduledFuture<V> {
override fun getDelay(timeUnit: TimeUnit): Long {
return 0
}
override fun compareTo(other: Delayed): Int {
return -1
}
}
companion object {
private const val TAG = "ImmediateFuture"
/**
* Returns a future that contains a null value.
*
*
* This should be used any time a null value is needed as it uses a static ListenableFuture
* that contains null, and thus will not allocate.
*/
fun <V> nullFuture(): ListenableFuture<V> {
return ImmediateSuccessfulFuture(null)
}
}
}