mirror of https://github.com/NekoX-Dev/NekoX.git
73 lines
2.3 KiB
Java
73 lines
2.3 KiB
Java
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.exoplayer2.drm;
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/**
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* A reference-counted resource used in the decryption of media samples.
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*
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* @param <T> The reference type with which to make {@link Owner#onLastReferenceReleased} calls.
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* Subclasses are expected to pass themselves.
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*/
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public abstract class DecryptionResource<T extends DecryptionResource<T>> {
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/**
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* Implemented by the class in charge of managing a {@link DecryptionResource resource's}
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* lifecycle.
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*/
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public interface Owner<T extends DecryptionResource<T>> {
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/**
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* Called when the last reference to a {@link DecryptionResource} is {@link #releaseReference()
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* released}.
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*/
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void onLastReferenceReleased(T resource);
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}
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// TODO: Consider adding a handler on which the owner should be called.
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private final DecryptionResource.Owner<T> owner;
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private int referenceCount;
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/**
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* Creates a new instance with reference count zero.
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*
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* @param owner The owner of this instance.
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*/
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public DecryptionResource(Owner<T> owner) {
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this.owner = owner;
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referenceCount = 0;
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}
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/** Increases by one the reference count for this resource. */
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public void acquireReference() {
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referenceCount++;
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}
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/**
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* Decreases by one the reference count for this resource, and notifies the owner if said count
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* reached zero as a result of this operation.
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*
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* <p>Must only be called as releasing counter-part of {@link #acquireReference()}.
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*/
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@SuppressWarnings("unchecked")
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public void releaseReference() {
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if (--referenceCount == 0) {
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owner.onLastReferenceReleased((T) this);
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} else if (referenceCount < 0) {
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throw new IllegalStateException("Illegal release of resource.");
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}
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}
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}
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