104 lines
3.4 KiB
Java
104 lines
3.4 KiB
Java
/*
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* Copyright (C) 2022 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.android.internal.util;
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import android.annotation.NonNull;
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import android.util.CharsetUtils;
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import com.android.modules.utils.FastDataInput;
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import dalvik.system.VMRuntime;
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import java.io.DataInput;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.concurrent.atomic.AtomicReference;
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/**
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* {@inheritDoc}
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* <p>
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* This decodes large code-points using 4-byte sequences, and <em>is not</em> compatible with the
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* {@link DataInput} API contract, which specifies that large code-points must be encoded with
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* 3-byte sequences.
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*/
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public class ArtFastDataInput extends FastDataInput {
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private static AtomicReference<ArtFastDataInput> sInCache = new AtomicReference<>();
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private static VMRuntime sRuntime = VMRuntime.getRuntime();
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private final long mBufferPtr;
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public ArtFastDataInput(@NonNull InputStream in, int bufferSize) {
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super(in, bufferSize);
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mBufferPtr = sRuntime.addressOf(mBuffer);
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}
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/**
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* Obtain a {@link ArtFastDataInput} configured with the given
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* {@link InputStream} and which decodes large code-points using 4-byte
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* sequences.
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* <p>
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* This <em>is not</em> compatible with the {@link DataInput} API contract,
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* which specifies that large code-points must be encoded with 3-byte
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* sequences.
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*/
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public static ArtFastDataInput obtain(@NonNull InputStream in) {
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ArtFastDataInput instance = sInCache.getAndSet(null);
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if (instance != null) {
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instance.setInput(in);
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return instance;
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}
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return new ArtFastDataInput(in, DEFAULT_BUFFER_SIZE);
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}
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/**
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* Release a {@link ArtFastDataInput} to potentially be recycled. You must not
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* interact with the object after releasing it.
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*/
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@Override
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public void release() {
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super.release();
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if (mBufferCap == DEFAULT_BUFFER_SIZE) {
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// Try to return to the cache.
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sInCache.compareAndSet(null, this);
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}
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}
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@Override
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public byte[] newByteArray(int bufferSize) {
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return (byte[]) sRuntime.newNonMovableArray(byte.class, bufferSize);
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}
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@Override
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public String readUTF() throws IOException {
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// Attempt to read directly from buffer space if there's enough room,
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// otherwise fall back to chunking into place
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final int len = readUnsignedShort();
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if (mBufferCap > len) {
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if (mBufferLim - mBufferPos < len) fill(len);
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final String res = CharsetUtils.fromModifiedUtf8Bytes(mBufferPtr, mBufferPos, len);
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mBufferPos += len;
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return res;
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} else {
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final byte[] tmp = (byte[]) sRuntime.newNonMovableArray(byte.class, len + 1);
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readFully(tmp, 0, len);
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return CharsetUtils.fromModifiedUtf8Bytes(sRuntime.addressOf(tmp), 0, len);
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}
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}
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}
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