f9001b9fc0
Motivation: The internal.hpack classes are no longer exposed in our public APIs and can be made package private in the http2 package. Modifications: - Make the hpack classes package private in the http2 package Result: Less APIs exposed as public.
195 lines
5.8 KiB
Java
195 lines
5.8 KiB
Java
/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. 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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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/*
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* Copyright 2014 Twitter, Inc.
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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 io.netty.handler.codec.http2;
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import io.netty.buffer.ByteBuf;
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import io.netty.util.AsciiString;
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import io.netty.util.ByteProcessor;
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import io.netty.util.internal.ObjectUtil;
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import io.netty.util.internal.PlatformDependent;
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final class HpackHuffmanEncoder {
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private final int[] codes;
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private final byte[] lengths;
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private final EncodedLengthProcessor encodedLengthProcessor = new EncodedLengthProcessor();
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private final EncodeProcessor encodeProcessor = new EncodeProcessor();
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HpackHuffmanEncoder() {
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this(HpackUtil.HUFFMAN_CODES, HpackUtil.HUFFMAN_CODE_LENGTHS);
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}
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/**
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* Creates a new Huffman encoder with the specified Huffman coding.
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*
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* @param codes the Huffman codes indexed by symbol
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* @param lengths the length of each Huffman code
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*/
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private HpackHuffmanEncoder(int[] codes, byte[] lengths) {
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this.codes = codes;
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this.lengths = lengths;
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}
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/**
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* Compresses the input string literal using the Huffman coding.
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*
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* @param out the output stream for the compressed data
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* @param data the string literal to be Huffman encoded
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*/
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public void encode(ByteBuf out, CharSequence data) {
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ObjectUtil.checkNotNull(out, "out");
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if (data instanceof AsciiString) {
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AsciiString string = (AsciiString) data;
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try {
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encodeProcessor.out = out;
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string.forEachByte(encodeProcessor);
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} catch (Exception e) {
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PlatformDependent.throwException(e);
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} finally {
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encodeProcessor.end();
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}
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} else {
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encodeSlowPath(out, data);
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}
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}
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private void encodeSlowPath(ByteBuf out, CharSequence data) {
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long current = 0;
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int n = 0;
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for (int i = 0; i < data.length(); i++) {
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int b = data.charAt(i) & 0xFF;
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int code = codes[b];
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int nbits = lengths[b];
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current <<= nbits;
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current |= code;
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n += nbits;
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while (n >= 8) {
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n -= 8;
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out.writeByte((int) (current >> n));
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}
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}
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if (n > 0) {
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current <<= 8 - n;
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current |= 0xFF >>> n; // this should be EOS symbol
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out.writeByte((int) current);
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}
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}
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/**
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* Returns the number of bytes required to Huffman encode the input string literal.
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*
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* @param data the string literal to be Huffman encoded
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* @return the number of bytes required to Huffman encode {@code data}
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*/
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int getEncodedLength(CharSequence data) {
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if (data instanceof AsciiString) {
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AsciiString string = (AsciiString) data;
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try {
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encodedLengthProcessor.reset();
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string.forEachByte(encodedLengthProcessor);
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return encodedLengthProcessor.length();
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} catch (Exception e) {
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PlatformDependent.throwException(e);
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return -1;
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}
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} else {
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return getEncodedLengthSlowPath(data);
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}
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}
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private int getEncodedLengthSlowPath(CharSequence data) {
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long len = 0;
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for (int i = 0; i < data.length(); i++) {
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len += lengths[data.charAt(i) & 0xFF];
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}
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return (int) ((len + 7) >> 3);
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}
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private final class EncodeProcessor implements ByteProcessor {
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ByteBuf out;
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private long current;
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private int n;
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@Override
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public boolean process(byte value) {
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int b = value & 0xFF;
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int nbits = lengths[b];
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current <<= nbits;
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current |= codes[b];
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n += nbits;
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while (n >= 8) {
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n -= 8;
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out.writeByte((int) (current >> n));
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}
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return true;
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}
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void end() {
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try {
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if (n > 0) {
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current <<= 8 - n;
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current |= 0xFF >>> n; // this should be EOS symbol
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out.writeByte((int) current);
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}
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} finally {
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out = null;
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current = 0;
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n = 0;
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}
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}
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}
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private final class EncodedLengthProcessor implements ByteProcessor {
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private long len;
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@Override
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public boolean process(byte value) {
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len += lengths[value & 0xFF];
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return true;
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}
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void reset() {
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len = 0;
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}
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int length() {
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return (int) ((len + 7) >> 3);
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}
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}
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}
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