ArrayRingBuffer.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.core.internal.utils;
import androidx.annotation.GuardedBy;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.util.ArrayDeque;
/**
* Implements {@link RingBuffer} with an {@link ArrayDeque}.
*
* @param <T> the type of elements stored in the RingBuffer.
*/
public class ArrayRingBuffer<T> implements RingBuffer<T> {
private static final String TAG = "ZslRingBuffer";
private final int mRingBufferCapacity;
@GuardedBy("mLock")
private final ArrayDeque<T> mBuffer;
private final Object mLock = new Object();
@Nullable final OnRemoveCallback<T> mOnRemoveCallback;
public ArrayRingBuffer(int ringBufferCapacity) {
this(ringBufferCapacity, null);
}
public ArrayRingBuffer(int ringBufferCapacity, @Nullable OnRemoveCallback<T> onRemoveCallback) {
mRingBufferCapacity = ringBufferCapacity;
mBuffer = new ArrayDeque<>(mRingBufferCapacity);
mOnRemoveCallback = onRemoveCallback;
}
@Override
public void enqueue(@NonNull T element) {
T removedItem = null;
synchronized (mLock) {
if (mBuffer.size() >= mRingBufferCapacity) {
removedItem = this.dequeue();
}
mBuffer.addFirst(element);
}
if (mOnRemoveCallback != null && removedItem != null) {
mOnRemoveCallback.onRemove(removedItem);
}
}
@Override
public @NonNull T dequeue() {
synchronized (mLock) {
return mBuffer.removeLast();
}
}
@Override
public int getMaxCapacity() {
return mRingBufferCapacity;
}
@Override
public boolean isEmpty() {
synchronized (mLock) {
return mBuffer.isEmpty();
}
}
}