ArrayDequeRingBuffer.java
/*
* Copyright 2022 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.video.internal.utils;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.camera.core.Logger;
import androidx.core.util.Preconditions;
import java.util.ArrayDeque;
import java.util.Queue;
/**
* Implements {@link RingBuffer} with an {@link ArrayDeque}.
*
* <p> A {@link ArrayDequeRingBuffer} must be configured with a maximum size. Each time an element
* is added to the {@link ArrayDequeRingBuffer} and its size reaches maximum, the element at the
* head of the {@link ArrayDequeRingBuffer} will be removed.
*
* <p> This class is not thread-safe, and does not accept null elements.
*
* @param <E> the type of elements stored in the RingBuffer
*/
@RequiresApi(21) // TODO(b/200306659): Remove and replace with annotation on package-info.java
public class ArrayDequeRingBuffer<E> implements RingBuffer<E> {
private static final String TAG = "ArrayDequeRingBuffer";
private final int mCapacity;
private final Queue<E> mQueue = new ArrayDeque<>();
public ArrayDequeRingBuffer(int capacity) {
Preconditions.checkArgument(capacity > 0, "The capacity should be greater than 0.");
mCapacity = capacity;
}
/** {@inheritDoc}
*
* @throws NullPointerException if {@code data} is {@code null}.
*/
@Override
public boolean offer(@NonNull E data) {
Preconditions.checkNotNull(data);
if (!mQueue.offer(data)) {
return false;
}
while (size() > mCapacity) {
poll();
Logger.d(TAG, "Head data is dropped because the ring buffer reached its capacity.");
}
return true;
}
/** {@inheritDoc} */
@Nullable
@Override
public E poll() {
return mQueue.poll();
}
/** {@inheritDoc} */
@Nullable
@Override
public E peek() {
return mQueue.peek();
}
/** {@inheritDoc} */
@Override
public int capacity() {
return mCapacity;
}
/** {@inheritDoc} */
@Override
public int size() {
return mQueue.size();
}
/** {@inheritDoc} */
@Override
public boolean isEmpty() {
return mQueue.isEmpty();
}
/** {@inheritDoc} */
@Override
public void clear() {
mQueue.clear();
}
}