| /* |
| * Copyright (C) 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 |
| * |
| * 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 com.android.server.wifi.util; |
| |
| import android.annotation.NonNull; |
| |
| import java.util.ArrayList; |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| /** |
| * Utility class for keeping a reletively small List of values, sorted by most recently added |
| * first. |
| * @param <E> |
| */ |
| public class LruList<E> { |
| private int mSize; |
| private LinkedList<E> mLinkedList; |
| |
| /** |
| * Creates a new LruList capped by maxSize. |
| * @param maxSize max allowed size of the LruList |
| */ |
| public LruList(int maxSize) { |
| mSize = maxSize; |
| mLinkedList = new LinkedList<E>(); |
| } |
| |
| /** |
| * Add an entry. If the entry already exists then it will be moved to the front. Otherwise, |
| * a new entry will be added. |
| * If this operation makes the LruList exceed the max allowed size, then the least recently |
| * added entry will be removed. |
| * @param entry |
| */ |
| public void add(@NonNull E entry) { |
| if (entry == null) { |
| return; |
| } |
| int index = mLinkedList.indexOf(entry); |
| if (index >= 0) { |
| mLinkedList.remove(index); |
| } |
| mLinkedList.addFirst(entry); |
| while (mLinkedList.size() > mSize) { |
| mLinkedList.removeLast(); |
| } |
| } |
| |
| /** |
| * Remove an entry from list. |
| */ |
| public void remove(@NonNull E entry) { |
| if (entry == null) { |
| return; |
| } |
| int index = mLinkedList.indexOf(entry); |
| if (index < 0) { |
| return; |
| } |
| mLinkedList.remove(index); |
| } |
| |
| /** |
| * Returns the list of entries sorted by most recently added entries first. |
| * @return |
| */ |
| public @NonNull List<E> getEntries() { |
| return new ArrayList<E>(mLinkedList); |
| } |
| |
| /** |
| * Gets the number of entries in this LruList. |
| */ |
| public int size() { |
| return mLinkedList.size(); |
| } |
| |
| /** |
| * Get the index in the list of the input entry. |
| * If not in the list will return -1. |
| * If in the list, smaller index is more recently added. |
| */ |
| public int indexOf(E entry) { |
| return mLinkedList.indexOf(entry); |
| } |
| } |