| /* |
| * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.internal.net.http.hpack; |
| |
| import jdk.internal.net.http.hpack.HPACK.BufferUpdateConsumer; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.util.List; |
| import java.util.Objects; |
| |
| import static jdk.internal.net.http.hpack.HPACK.bytesForBits; |
| |
| public final class QuickHuffman { |
| |
| /* |
| * Mapping of characters to their code information. Code information |
| * consists of a code value and a code length. Both components are packed in |
| * a single long as follows: |
| * |
| * MSB LSB |
| * +----------------+----------------+ |
| * |~code | length~| |
| * +----------------+----------------+ |
| * |<----- 32 ----->|<----- 32 ----->| |
| * |<------------- 64 -------------->| |
| * |
| * The leftmost 32 bits hold the code value. This value is aligned left (or |
| * MSB). The rightmost 32 bits hold the code length. This length is aligned |
| * right (or LSB). Such structure is possible thanks to codes being up to 30 |
| * bits long and their lengths being up to 5 bits long (length = 5..30). |
| * This allows both components to fit into long and, thus, better locality. |
| * |
| * Input strings never contain EOS. Thus there's no need to provide EOS |
| * mapping. Hence, the length of the array is 256, not 257. |
| */ |
| private static final long[] codes = new long[256]; |
| |
| private static long codeValueOf(char c) { |
| return codes[c] & 0xffffffff00000000L; |
| } |
| |
| private static long codeLengthOf(char c) { |
| return codes[c] & 0x00000000ffffffffL; |
| } |
| |
| private static final int EOS_LENGTH = 30; |
| private static final int EOS_LSB = 0x3fffffff; |
| // EOS_LSB is casted to long before the shift, to allow long shift (6 bits) |
| // instead of int shift (5 bits): |
| private static final long EOS_MSB = ((long) EOS_LSB) << (64 - EOS_LENGTH); |
| |
| /* |
| * Huffman trie. |
| * |
| * The root node leads to 257 descendant leaf nodes, of which 256 nodes |
| * correspond to characters and 1 node correspond to EOS. |
| */ |
| private static final Node root = buildTrie(); |
| |
| private static Node buildTrie() { |
| TemporaryNode tmpRoot = new TemporaryNode(); |
| addChar(tmpRoot, 0, 0x1ff8, 13); |
| addChar(tmpRoot, 1, 0x7fffd8, 23); |
| addChar(tmpRoot, 2, 0xfffffe2, 28); |
| addChar(tmpRoot, 3, 0xfffffe3, 28); |
| addChar(tmpRoot, 4, 0xfffffe4, 28); |
| addChar(tmpRoot, 5, 0xfffffe5, 28); |
| addChar(tmpRoot, 6, 0xfffffe6, 28); |
| addChar(tmpRoot, 7, 0xfffffe7, 28); |
| addChar(tmpRoot, 8, 0xfffffe8, 28); |
| addChar(tmpRoot, 9, 0xffffea, 24); |
| addChar(tmpRoot, 10, 0x3ffffffc, 30); |
| addChar(tmpRoot, 11, 0xfffffe9, 28); |
| addChar(tmpRoot, 12, 0xfffffea, 28); |
| addChar(tmpRoot, 13, 0x3ffffffd, 30); |
| addChar(tmpRoot, 14, 0xfffffeb, 28); |
| addChar(tmpRoot, 15, 0xfffffec, 28); |
| addChar(tmpRoot, 16, 0xfffffed, 28); |
| addChar(tmpRoot, 17, 0xfffffee, 28); |
| addChar(tmpRoot, 18, 0xfffffef, 28); |
| addChar(tmpRoot, 19, 0xffffff0, 28); |
| addChar(tmpRoot, 20, 0xffffff1, 28); |
| addChar(tmpRoot, 21, 0xffffff2, 28); |
| addChar(tmpRoot, 22, 0x3ffffffe, 30); |
| addChar(tmpRoot, 23, 0xffffff3, 28); |
| addChar(tmpRoot, 24, 0xffffff4, 28); |
| addChar(tmpRoot, 25, 0xffffff5, 28); |
| addChar(tmpRoot, 26, 0xffffff6, 28); |
| addChar(tmpRoot, 27, 0xffffff7, 28); |
| addChar(tmpRoot, 28, 0xffffff8, 28); |
| addChar(tmpRoot, 29, 0xffffff9, 28); |
| addChar(tmpRoot, 30, 0xffffffa, 28); |
| addChar(tmpRoot, 31, 0xffffffb, 28); |
| addChar(tmpRoot, 32, 0x14, 6); |
| addChar(tmpRoot, 33, 0x3f8, 10); |
| addChar(tmpRoot, 34, 0x3f9, 10); |
| addChar(tmpRoot, 35, 0xffa, 12); |
| addChar(tmpRoot, 36, 0x1ff9, 13); |
| addChar(tmpRoot, 37, 0x15, 6); |
| addChar(tmpRoot, 38, 0xf8, 8); |
| addChar(tmpRoot, 39, 0x7fa, 11); |
| addChar(tmpRoot, 40, 0x3fa, 10); |
| addChar(tmpRoot, 41, 0x3fb, 10); |
| addChar(tmpRoot, 42, 0xf9, 8); |
| addChar(tmpRoot, 43, 0x7fb, 11); |
| addChar(tmpRoot, 44, 0xfa, 8); |
| addChar(tmpRoot, 45, 0x16, 6); |
| addChar(tmpRoot, 46, 0x17, 6); |
| addChar(tmpRoot, 47, 0x18, 6); |
| addChar(tmpRoot, 48, 0x0, 5); |
| addChar(tmpRoot, 49, 0x1, 5); |
| addChar(tmpRoot, 50, 0x2, 5); |
| addChar(tmpRoot, 51, 0x19, 6); |
| addChar(tmpRoot, 52, 0x1a, 6); |
| addChar(tmpRoot, 53, 0x1b, 6); |
| addChar(tmpRoot, 54, 0x1c, 6); |
| addChar(tmpRoot, 55, 0x1d, 6); |
| addChar(tmpRoot, 56, 0x1e, 6); |
| addChar(tmpRoot, 57, 0x1f, 6); |
| addChar(tmpRoot, 58, 0x5c, 7); |
| addChar(tmpRoot, 59, 0xfb, 8); |
| addChar(tmpRoot, 60, 0x7ffc, 15); |
| addChar(tmpRoot, 61, 0x20, 6); |
| addChar(tmpRoot, 62, 0xffb, 12); |
| addChar(tmpRoot, 63, 0x3fc, 10); |
| addChar(tmpRoot, 64, 0x1ffa, 13); |
| addChar(tmpRoot, 65, 0x21, 6); |
| addChar(tmpRoot, 66, 0x5d, 7); |
| addChar(tmpRoot, 67, 0x5e, 7); |
| addChar(tmpRoot, 68, 0x5f, 7); |
| addChar(tmpRoot, 69, 0x60, 7); |
| addChar(tmpRoot, 70, 0x61, 7); |
| addChar(tmpRoot, 71, 0x62, 7); |
| addChar(tmpRoot, 72, 0x63, 7); |
| addChar(tmpRoot, 73, 0x64, 7); |
| addChar(tmpRoot, 74, 0x65, 7); |
| addChar(tmpRoot, 75, 0x66, 7); |
| addChar(tmpRoot, 76, 0x67, 7); |
| addChar(tmpRoot, 77, 0x68, 7); |
| addChar(tmpRoot, 78, 0x69, 7); |
| addChar(tmpRoot, 79, 0x6a, 7); |
| addChar(tmpRoot, 80, 0x6b, 7); |
| addChar(tmpRoot, 81, 0x6c, 7); |
| addChar(tmpRoot, 82, 0x6d, 7); |
| addChar(tmpRoot, 83, 0x6e, 7); |
| addChar(tmpRoot, 84, 0x6f, 7); |
| addChar(tmpRoot, 85, 0x70, 7); |
| addChar(tmpRoot, 86, 0x71, 7); |
| addChar(tmpRoot, 87, 0x72, 7); |
| addChar(tmpRoot, 88, 0xfc, 8); |
| addChar(tmpRoot, 89, 0x73, 7); |
| addChar(tmpRoot, 90, 0xfd, 8); |
| addChar(tmpRoot, 91, 0x1ffb, 13); |
| addChar(tmpRoot, 92, 0x7fff0, 19); |
| addChar(tmpRoot, 93, 0x1ffc, 13); |
| addChar(tmpRoot, 94, 0x3ffc, 14); |
| addChar(tmpRoot, 95, 0x22, 6); |
| addChar(tmpRoot, 96, 0x7ffd, 15); |
| addChar(tmpRoot, 97, 0x3, 5); |
| addChar(tmpRoot, 98, 0x23, 6); |
| addChar(tmpRoot, 99, 0x4, 5); |
| addChar(tmpRoot, 100, 0x24, 6); |
| addChar(tmpRoot, 101, 0x5, 5); |
| addChar(tmpRoot, 102, 0x25, 6); |
| addChar(tmpRoot, 103, 0x26, 6); |
| addChar(tmpRoot, 104, 0x27, 6); |
| addChar(tmpRoot, 105, 0x6, 5); |
| addChar(tmpRoot, 106, 0x74, 7); |
| addChar(tmpRoot, 107, 0x75, 7); |
| addChar(tmpRoot, 108, 0x28, 6); |
| addChar(tmpRoot, 109, 0x29, 6); |
| addChar(tmpRoot, 110, 0x2a, 6); |
| addChar(tmpRoot, 111, 0x7, 5); |
| addChar(tmpRoot, 112, 0x2b, 6); |
| addChar(tmpRoot, 113, 0x76, 7); |
| addChar(tmpRoot, 114, 0x2c, 6); |
| addChar(tmpRoot, 115, 0x8, 5); |
| addChar(tmpRoot, 116, 0x9, 5); |
| addChar(tmpRoot, 117, 0x2d, 6); |
| addChar(tmpRoot, 118, 0x77, 7); |
| addChar(tmpRoot, 119, 0x78, 7); |
| addChar(tmpRoot, 120, 0x79, 7); |
| addChar(tmpRoot, 121, 0x7a, 7); |
| addChar(tmpRoot, 122, 0x7b, 7); |
| addChar(tmpRoot, 123, 0x7ffe, 15); |
| addChar(tmpRoot, 124, 0x7fc, 11); |
| addChar(tmpRoot, 125, 0x3ffd, 14); |
| addChar(tmpRoot, 126, 0x1ffd, 13); |
| addChar(tmpRoot, 127, 0xffffffc, 28); |
| addChar(tmpRoot, 128, 0xfffe6, 20); |
| addChar(tmpRoot, 129, 0x3fffd2, 22); |
| addChar(tmpRoot, 130, 0xfffe7, 20); |
| addChar(tmpRoot, 131, 0xfffe8, 20); |
| addChar(tmpRoot, 132, 0x3fffd3, 22); |
| addChar(tmpRoot, 133, 0x3fffd4, 22); |
| addChar(tmpRoot, 134, 0x3fffd5, 22); |
| addChar(tmpRoot, 135, 0x7fffd9, 23); |
| addChar(tmpRoot, 136, 0x3fffd6, 22); |
| addChar(tmpRoot, 137, 0x7fffda, 23); |
| addChar(tmpRoot, 138, 0x7fffdb, 23); |
| addChar(tmpRoot, 139, 0x7fffdc, 23); |
| addChar(tmpRoot, 140, 0x7fffdd, 23); |
| addChar(tmpRoot, 141, 0x7fffde, 23); |
| addChar(tmpRoot, 142, 0xffffeb, 24); |
| addChar(tmpRoot, 143, 0x7fffdf, 23); |
| addChar(tmpRoot, 144, 0xffffec, 24); |
| addChar(tmpRoot, 145, 0xffffed, 24); |
| addChar(tmpRoot, 146, 0x3fffd7, 22); |
| addChar(tmpRoot, 147, 0x7fffe0, 23); |
| addChar(tmpRoot, 148, 0xffffee, 24); |
| addChar(tmpRoot, 149, 0x7fffe1, 23); |
| addChar(tmpRoot, 150, 0x7fffe2, 23); |
| addChar(tmpRoot, 151, 0x7fffe3, 23); |
| addChar(tmpRoot, 152, 0x7fffe4, 23); |
| addChar(tmpRoot, 153, 0x1fffdc, 21); |
| addChar(tmpRoot, 154, 0x3fffd8, 22); |
| addChar(tmpRoot, 155, 0x7fffe5, 23); |
| addChar(tmpRoot, 156, 0x3fffd9, 22); |
| addChar(tmpRoot, 157, 0x7fffe6, 23); |
| addChar(tmpRoot, 158, 0x7fffe7, 23); |
| addChar(tmpRoot, 159, 0xffffef, 24); |
| addChar(tmpRoot, 160, 0x3fffda, 22); |
| addChar(tmpRoot, 161, 0x1fffdd, 21); |
| addChar(tmpRoot, 162, 0xfffe9, 20); |
| addChar(tmpRoot, 163, 0x3fffdb, 22); |
| addChar(tmpRoot, 164, 0x3fffdc, 22); |
| addChar(tmpRoot, 165, 0x7fffe8, 23); |
| addChar(tmpRoot, 166, 0x7fffe9, 23); |
| addChar(tmpRoot, 167, 0x1fffde, 21); |
| addChar(tmpRoot, 168, 0x7fffea, 23); |
| addChar(tmpRoot, 169, 0x3fffdd, 22); |
| addChar(tmpRoot, 170, 0x3fffde, 22); |
| addChar(tmpRoot, 171, 0xfffff0, 24); |
| addChar(tmpRoot, 172, 0x1fffdf, 21); |
| addChar(tmpRoot, 173, 0x3fffdf, 22); |
| addChar(tmpRoot, 174, 0x7fffeb, 23); |
| addChar(tmpRoot, 175, 0x7fffec, 23); |
| addChar(tmpRoot, 176, 0x1fffe0, 21); |
| addChar(tmpRoot, 177, 0x1fffe1, 21); |
| addChar(tmpRoot, 178, 0x3fffe0, 22); |
| addChar(tmpRoot, 179, 0x1fffe2, 21); |
| addChar(tmpRoot, 180, 0x7fffed, 23); |
| addChar(tmpRoot, 181, 0x3fffe1, 22); |
| addChar(tmpRoot, 182, 0x7fffee, 23); |
| addChar(tmpRoot, 183, 0x7fffef, 23); |
| addChar(tmpRoot, 184, 0xfffea, 20); |
| addChar(tmpRoot, 185, 0x3fffe2, 22); |
| addChar(tmpRoot, 186, 0x3fffe3, 22); |
| addChar(tmpRoot, 187, 0x3fffe4, 22); |
| addChar(tmpRoot, 188, 0x7ffff0, 23); |
| addChar(tmpRoot, 189, 0x3fffe5, 22); |
| addChar(tmpRoot, 190, 0x3fffe6, 22); |
| addChar(tmpRoot, 191, 0x7ffff1, 23); |
| addChar(tmpRoot, 192, 0x3ffffe0, 26); |
| addChar(tmpRoot, 193, 0x3ffffe1, 26); |
| addChar(tmpRoot, 194, 0xfffeb, 20); |
| addChar(tmpRoot, 195, 0x7fff1, 19); |
| addChar(tmpRoot, 196, 0x3fffe7, 22); |
| addChar(tmpRoot, 197, 0x7ffff2, 23); |
| addChar(tmpRoot, 198, 0x3fffe8, 22); |
| addChar(tmpRoot, 199, 0x1ffffec, 25); |
| addChar(tmpRoot, 200, 0x3ffffe2, 26); |
| addChar(tmpRoot, 201, 0x3ffffe3, 26); |
| addChar(tmpRoot, 202, 0x3ffffe4, 26); |
| addChar(tmpRoot, 203, 0x7ffffde, 27); |
| addChar(tmpRoot, 204, 0x7ffffdf, 27); |
| addChar(tmpRoot, 205, 0x3ffffe5, 26); |
| addChar(tmpRoot, 206, 0xfffff1, 24); |
| addChar(tmpRoot, 207, 0x1ffffed, 25); |
| addChar(tmpRoot, 208, 0x7fff2, 19); |
| addChar(tmpRoot, 209, 0x1fffe3, 21); |
| addChar(tmpRoot, 210, 0x3ffffe6, 26); |
| addChar(tmpRoot, 211, 0x7ffffe0, 27); |
| addChar(tmpRoot, 212, 0x7ffffe1, 27); |
| addChar(tmpRoot, 213, 0x3ffffe7, 26); |
| addChar(tmpRoot, 214, 0x7ffffe2, 27); |
| addChar(tmpRoot, 215, 0xfffff2, 24); |
| addChar(tmpRoot, 216, 0x1fffe4, 21); |
| addChar(tmpRoot, 217, 0x1fffe5, 21); |
| addChar(tmpRoot, 218, 0x3ffffe8, 26); |
| addChar(tmpRoot, 219, 0x3ffffe9, 26); |
| addChar(tmpRoot, 220, 0xffffffd, 28); |
| addChar(tmpRoot, 221, 0x7ffffe3, 27); |
| addChar(tmpRoot, 222, 0x7ffffe4, 27); |
| addChar(tmpRoot, 223, 0x7ffffe5, 27); |
| addChar(tmpRoot, 224, 0xfffec, 20); |
| addChar(tmpRoot, 225, 0xfffff3, 24); |
| addChar(tmpRoot, 226, 0xfffed, 20); |
| addChar(tmpRoot, 227, 0x1fffe6, 21); |
| addChar(tmpRoot, 228, 0x3fffe9, 22); |
| addChar(tmpRoot, 229, 0x1fffe7, 21); |
| addChar(tmpRoot, 230, 0x1fffe8, 21); |
| addChar(tmpRoot, 231, 0x7ffff3, 23); |
| addChar(tmpRoot, 232, 0x3fffea, 22); |
| addChar(tmpRoot, 233, 0x3fffeb, 22); |
| addChar(tmpRoot, 234, 0x1ffffee, 25); |
| addChar(tmpRoot, 235, 0x1ffffef, 25); |
| addChar(tmpRoot, 236, 0xfffff4, 24); |
| addChar(tmpRoot, 237, 0xfffff5, 24); |
| addChar(tmpRoot, 238, 0x3ffffea, 26); |
| addChar(tmpRoot, 239, 0x7ffff4, 23); |
| addChar(tmpRoot, 240, 0x3ffffeb, 26); |
| addChar(tmpRoot, 241, 0x7ffffe6, 27); |
| addChar(tmpRoot, 242, 0x3ffffec, 26); |
| addChar(tmpRoot, 243, 0x3ffffed, 26); |
| addChar(tmpRoot, 244, 0x7ffffe7, 27); |
| addChar(tmpRoot, 245, 0x7ffffe8, 27); |
| addChar(tmpRoot, 246, 0x7ffffe9, 27); |
| addChar(tmpRoot, 247, 0x7ffffea, 27); |
| addChar(tmpRoot, 248, 0x7ffffeb, 27); |
| addChar(tmpRoot, 249, 0xffffffe, 28); |
| addChar(tmpRoot, 250, 0x7ffffec, 27); |
| addChar(tmpRoot, 251, 0x7ffffed, 27); |
| addChar(tmpRoot, 252, 0x7ffffee, 27); |
| addChar(tmpRoot, 253, 0x7ffffef, 27); |
| addChar(tmpRoot, 254, 0x7fffff0, 27); |
| addChar(tmpRoot, 255, 0x3ffffee, 26); |
| addEOS (tmpRoot, 256, EOS_LSB, EOS_LENGTH); |
| |
| // The difference in performance can always be checked by not using |
| // the immutable trie: |
| // return tmpRoot; |
| return ImmutableNode.copyOf(tmpRoot); |
| } |
| |
| private QuickHuffman() { } |
| |
| private static void addChar(Node root, int symbol, int code, int bitLength) |
| { |
| addLeaf(root, (char) symbol, code, bitLength, false); |
| long value = ((long) code) << (64 - bitLength); // re-align MSB <- LSB |
| codes[symbol] = value | bitLength; |
| } |
| |
| private static void addEOS(Node root, int symbol, int code, int bitLength) |
| { |
| addLeaf(root, (char) symbol, code, bitLength, true); |
| } |
| |
| private static void addLeaf(Node root, |
| char symbol, |
| int code, |
| int bitLength, |
| boolean isEOS) |
| { |
| assert 0 < bitLength && bitLength <= 32 : bitLength; |
| Node curr = root; |
| int nBytes = bytesForBits(bitLength); |
| // The number of bits the code needs to be shifted to the left in order |
| // to align with the byte #nBytes boundary: |
| int align = (nBytes << 3) - bitLength; |
| code <<= align; |
| // descend the trie until the last element |
| int l = 0; |
| for (int i = 0, probe = 0xff << ((nBytes - 1) << 3); |
| i < nBytes - 1; |
| i++, probe >>>= 8) |
| { |
| curr.setEOSPath(curr.isEOSPath() | isEOS); |
| int idx = (code & probe) >>> ((nBytes - 1 - i) << 3); |
| curr = curr.getOrCreateChild(idx); |
| curr.setLength(8); |
| l += 8; |
| } |
| // Assign the same char to all byte variants. For example, if the code |
| // and its length are 00011b and 5 respectively (letter 'a') then, in |
| // order to be able to match any byte starting with 00011b prefix, |
| // the following nodes need to be created: |
| // |
| // 00011000b, 00011001b, 00011010b, 00011011b, 00011100b, 00011101b, |
| // 00011110b and 00011111b |
| int idx = code & 0xff; |
| curr.setEOSPath(curr.isEOSPath() | isEOS); |
| for (int i = 0; i < (1 << align); i++) { |
| Node child = curr.getOrCreateChild(idx | i); |
| child.setSymbol(symbol); |
| child.setEOSPath(child.isEOSPath() | isEOS); |
| child.setLength(bitLength - l); |
| } |
| } |
| |
| /* |
| * A node in the Huffman trie. |
| */ |
| interface Node { |
| |
| boolean isEOSPath(); |
| |
| void setEOSPath(boolean value); |
| |
| boolean isLeaf(); |
| |
| Node getChild(int index); |
| |
| Node getOrCreateChild(int index); |
| |
| Node[] getChildren(); |
| |
| char getSymbol(); |
| |
| void setSymbol(char symbol); |
| |
| int getLength(); |
| |
| void setLength(int value); |
| } |
| |
| /* |
| * Mutable nodes used for initial construction of the Huffman trie. |
| * (These nodes are perfectly ok to be used after that.) |
| */ |
| static final class TemporaryNode implements Node { |
| |
| private char symbol; |
| private boolean eosPath; |
| private TemporaryNode[] children; |
| private int length; |
| |
| @Override |
| public TemporaryNode getOrCreateChild(int index) { |
| ensureChildrenExist(); |
| if (children[index] == null) { |
| children[index] = new TemporaryNode(); |
| } |
| return children[index]; |
| } |
| |
| private void ensureChildrenExist() { |
| if (children == null) { |
| children = new TemporaryNode[256]; |
| } |
| } |
| |
| @Override |
| public boolean isLeaf() { |
| return children == null; |
| } |
| |
| @Override |
| public boolean isEOSPath() { |
| return eosPath; |
| } |
| |
| @Override |
| public void setEOSPath(boolean value) { |
| eosPath = value; |
| } |
| |
| @Override |
| public TemporaryNode getChild(int index) { |
| ensureChildrenExist(); |
| return children[index]; |
| } |
| |
| @Override |
| public Node[] getChildren() { |
| if (children == null) { |
| return new Node[0]; |
| } |
| return children; |
| } |
| |
| @Override |
| public char getSymbol() { |
| return symbol; |
| } |
| |
| @Override |
| public int getLength() { |
| return length; |
| } |
| |
| @Override |
| public void setSymbol(char value) { |
| this.symbol = value; |
| } |
| |
| @Override |
| public void setLength(int value) { |
| this.length = value; |
| } |
| } |
| |
| /* |
| * Immutable node used to construct traversal-only Huffman trie. |
| * |
| * Once the trie has been built, the support of modifications is no longer |
| * required. An immutable trie should be used. Not only it will help to |
| * catch possible bugs, but hopefully speedup the traversal operations. |
| */ |
| static final class ImmutableNode implements Node { |
| |
| private final char symbol; |
| private final boolean eosPath; |
| private final int length; |
| private final List<ImmutableNode> children; |
| |
| public static ImmutableNode copyOf(Node node) { |
| if (node.isLeaf()) { |
| return new ImmutableNode(node.getSymbol(), node.isEOSPath(), |
| node.getLength()); |
| } |
| Node[] children = node.getChildren(); |
| ImmutableNode[] immutableChildren = new ImmutableNode[children.length]; |
| for (int i = 0; i < children.length; i++) { |
| immutableChildren[i] = copyOf(children[i]); |
| } |
| return new ImmutableNode(node.isEOSPath(), node.getLength(), |
| immutableChildren); |
| } |
| |
| /* Creates a leaf node */ |
| private ImmutableNode(char symbol, |
| boolean eosPath, |
| int length) { |
| this.symbol = symbol; |
| this.eosPath = eosPath; |
| this.length = length; |
| this.children = List.of(); |
| } |
| |
| /* Creates a node with children */ |
| private ImmutableNode(boolean eosPath, |
| int length, |
| ImmutableNode[] children) |
| { |
| this.symbol = 0; |
| this.eosPath = eosPath; |
| this.length = length; |
| if (children.length == 0) { |
| throw new IllegalArgumentException(); |
| } |
| // A list produced by List.of should not be slower than array for |
| // accessing elements by index, and hopefully use additional |
| // optimizations (e.g. jdk.internal.vm.annotation.Stable) |
| this.children = List.of(children); |
| } |
| |
| @Override |
| public boolean isLeaf() { |
| return children.isEmpty(); |
| } |
| |
| @Override |
| public boolean isEOSPath() { |
| return eosPath; |
| } |
| |
| @Override |
| public void setEOSPath(boolean value) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public ImmutableNode getChild(int index) { |
| return children.get(index); |
| } |
| |
| @Override |
| public ImmutableNode getOrCreateChild(int index) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public ImmutableNode[] getChildren() { |
| // This method is not expected to be called on an immutable node. |
| // If it is called, it requires some investigation. |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public char getSymbol() { |
| return symbol; |
| } |
| |
| @Override |
| public void setSymbol(char symbol) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public int getLength() { |
| return length; |
| } |
| |
| @Override |
| public void setLength(int value) { |
| throw new UnsupportedOperationException(); |
| } |
| } |
| |
| static final class Reader implements Huffman.Reader { |
| |
| private final BufferUpdateConsumer UPDATER = |
| (buf, bufLen) -> { |
| buffer = buf; |
| bufferLen = bufLen; |
| }; |
| |
| private Node curr = root; // current position in the trie |
| private long buffer; // bits left from the previous match (aligned to the left, or MSB) |
| private int bufferLen; // number of bits in the buffer |
| private int len; // length (in bits) of path to curr |
| private boolean done; |
| |
| @Override |
| public void read(ByteBuffer source, |
| Appendable destination, |
| boolean isLast) throws IOException |
| { |
| while (!done) { |
| int remaining = source.remaining(); |
| int nBytes = HPACK.read(source, buffer, bufferLen, UPDATER); |
| // write as much as possible |
| while (true) { |
| if (bufferLen < 8) { |
| if (nBytes < remaining) { // read again |
| break; |
| } else if (!isLast) { // exit the method to accept more input |
| return; |
| } else if (bufferLen > 0) { // no more data is expected, pad |
| // (this padding may be done more than once) |
| buffer |= ((0xff00000000000000L >>> bufferLen) |
| & 0xff00000000000000L); |
| // do not update bufferLen, since all those ones are |
| // synthetic and are appended merely for the sake of |
| // lookup |
| } else { |
| done = true; |
| break; |
| } |
| } |
| int idx = (int) (buffer >>> 56); |
| Node node = curr.getChild(idx); |
| if (node == null) { // TODO: TEST |
| throw new IOException("Unexpected byte"); |
| } |
| if (node.isLeaf()) { |
| if (node.getLength() > bufferLen) { // matched more than we actually could (because of padding) |
| throw new IOException( |
| "Not a EOS prefix padding or unexpected end of data"); |
| } |
| if (node.isEOSPath()) { |
| throw new IOException("Encountered EOS"); |
| } |
| destination.append(node.getSymbol()); |
| curr = root; |
| len = 0; |
| } else { |
| curr = node; |
| // because of the padding, we can't match more bits than |
| // there are currently in the buffer |
| len += Math.min(bufferLen, node.getLength()); |
| } |
| buffer <<= node.getLength(); |
| bufferLen -= node.getLength(); |
| } |
| if (done && (curr.isEOSPath() && len > 7)) { |
| throw new IOException( |
| "Padding is too long (len=" + len + ") " |
| + "or unexpected end of data"); |
| } |
| } |
| } |
| |
| @Override |
| public void reset() { |
| curr = root; |
| len = 0; |
| buffer = 0; |
| bufferLen = 0; |
| done = false; |
| } |
| } |
| |
| static final class Writer implements Huffman.Writer { |
| |
| private final BufferUpdateConsumer UPDATER = |
| (buf, bufLen) -> { |
| buffer = buf; |
| bufferLen = bufLen; |
| }; |
| |
| private CharSequence source; |
| private boolean padded; |
| private int pos; |
| private int end; |
| private long buffer; |
| private int bufferLen; |
| |
| @Override |
| public QuickHuffman.Writer from(CharSequence input, int start, int end) { |
| Objects.checkFromToIndex(start, end, input.length()); |
| this.pos = start; |
| this.end = end; |
| this.source = input; |
| return this; |
| } |
| |
| @Override |
| public boolean write(ByteBuffer destination) { |
| while (true) { |
| while (true) { // stuff codes into long |
| if (pos >= end) { |
| break; |
| } |
| char c = source.charAt(pos); |
| if (c > 255) { |
| throw new IllegalArgumentException("char=" + ((int) c)); |
| } |
| long len = codeLengthOf(c); |
| if (bufferLen + len <= 64) { |
| buffer |= (codeValueOf(c) >>> bufferLen); // append |
| bufferLen += len; |
| pos++; |
| } else { |
| break; |
| } |
| } |
| if (bufferLen == 0) { |
| return true; |
| } |
| if (pos >= end && !padded) { // no more input chars are expected, pad |
| padded = true; |
| // A long shift to 64 will result in the same long, not |
| // necessarily 0L. In which case padding will be performed |
| // incorrectly. If bufferLen is equal to 64, the shift (and |
| // padding) in not performed. |
| // (see https://docs.oracle.com/javase/specs/jls/se10/html/jls-15.html#jls-15.19) |
| if (bufferLen != 64) { |
| buffer |= (EOS_MSB >>> bufferLen); |
| bufferLen = bytesForBits(bufferLen) << 3; |
| } |
| } |
| int nBytes = HPACK.write(buffer, bufferLen, UPDATER, destination); |
| if (nBytes == 0) { |
| return false; |
| } |
| } |
| } |
| |
| @Override |
| public QuickHuffman.Writer reset() { |
| source = null; |
| buffer = 0; |
| bufferLen = 0; |
| end = 0; |
| pos = 0; |
| padded = false; |
| return this; |
| } |
| |
| @Override |
| public int lengthOf(CharSequence value, int start, int end) { |
| int len = 0; |
| for (int i = start; i < end; i++) { |
| char c = value.charAt(i); |
| len += codeLengthOf(c); |
| } |
| return bytesForBits(len); |
| } |
| } |
| } |
