| /* |
| * Copyright 2011 Google Inc. |
| * |
| * 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.google.ipc.invalidation.ticl; |
| |
| import java.util.Collection; |
| |
| /** |
| * Interface for a store that allows objects to be added/removed along with |
| * the ability to get the digest for the whole or partial set of those objects. |
| * |
| * @param <ElementType> the type of the element stored in this |
| * |
| */ |
| public interface DigestStore<ElementType> { |
| |
| /** Returns the number of elements. */ |
| int size(); |
| |
| /** Returns whether {@code element} is in the store. */ |
| boolean contains(ElementType element); |
| |
| /** |
| * Returns a digest of the desired objects. |
| * <p> |
| * NOTE: the digest computations <b>MUST NOT</b> depend on the order in which the elements |
| * were added. |
| */ |
| byte[] getDigest(); |
| |
| /** |
| * Returns the elements whose digest prefixes begin with the bit prefix {@code digestPrefix}. |
| * {@code prefixLen} is the length of {@code digestPrefix} in bits, which may be less than |
| * {@code digestPrefix.length} (and may be 0). The implementing class can return *more* objects |
| * than what has been specified by {@code digestPrefix}, e.g., it could return all the objects |
| * in the store. |
| */ |
| Collection<ElementType> getElements(byte[] digestPrefix, int prefixLen); |
| |
| /** |
| * Adds {@code element} to the store. No-op if {@code element} is already present. |
| * @return whether the element was added |
| */ |
| boolean add(ElementType element); |
| |
| /** |
| * Adds {@code elements} to the store. If any element in {@code elements} is already present, |
| * the addition is a no-op for that element. |
| * @return the elements that were added |
| */ |
| Collection<ElementType> add(Collection<ElementType> elements); |
| |
| /** |
| * Removes {@code element} from the store. No-op if {@code element} is not present. |
| * @return whether the element was removed |
| */ |
| boolean remove(ElementType element); |
| |
| /** |
| * Remove {@code elements} to the store. If any element in {@code elements} is not present, the |
| * removal is a no-op for that element. |
| * @return the elements that were removed |
| */ |
| Collection<ElementType> remove(Collection<ElementType> elements); |
| |
| /** Removes all elements in this and returns them. */ |
| Collection<ElementType> removeAll(); |
| } |