1 /* 2 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.internal.net.http.hpack; 27 28 import jdk.internal.net.http.hpack.HPACK.BufferUpdateConsumer; 29 30 import java.io.IOException; 31 import java.nio.ByteBuffer; 32 import java.util.List; 33 import java.util.Objects; 34 35 import static jdk.internal.net.http.hpack.HPACK.bytesForBits; 36 37 public final class QuickHuffman { 38 39 /* 40 * Mapping of characters to their code information. Code information 41 * consists of a code value and a code length. Both components are packed in 42 * a single long as follows: 43 * 44 * MSB LSB 45 * +----------------+----------------+ 46 * |~code | length~| 47 * +----------------+----------------+ 48 * |<----- 32 ----->|<----- 32 ----->| 49 * |<------------- 64 -------------->| 50 * 51 * The leftmost 32 bits hold the code value. This value is aligned left (or 52 * MSB). The rightmost 32 bits hold the code length. This length is aligned 53 * right (or LSB). Such structure is possible thanks to codes being up to 30 54 * bits long and their lengths being up to 5 bits long (length = 5..30). 55 * This allows both components to fit into long and, thus, better locality. 56 * 57 * Input strings never contain EOS. Thus there's no need to provide EOS 58 * mapping. Hence, the length of the array is 256, not 257. 59 */ 60 private static final long[] codes = new long[256]; 61 codeValueOf(char c)62 private static long codeValueOf(char c) { 63 return codes[c] & 0xffffffff00000000L; 64 } 65 codeLengthOf(char c)66 private static long codeLengthOf(char c) { 67 return codes[c] & 0x00000000ffffffffL; 68 } 69 70 private static final int EOS_LENGTH = 30; 71 private static final int EOS_LSB = 0x3fffffff; 72 // EOS_LSB is casted to long before the shift, to allow long shift (6 bits) 73 // instead of int shift (5 bits): 74 private static final long EOS_MSB = ((long) EOS_LSB) << (64 - EOS_LENGTH); 75 76 /* 77 * Huffman trie. 78 * 79 * The root node leads to 257 descendant leaf nodes, of which 256 nodes 80 * correspond to characters and 1 node correspond to EOS. 81 */ 82 private static final Node root = buildTrie(); 83 buildTrie()84 private static Node buildTrie() { 85 TemporaryNode tmpRoot = new TemporaryNode(); 86 addChar(tmpRoot, 0, 0x1ff8, 13); 87 addChar(tmpRoot, 1, 0x7fffd8, 23); 88 addChar(tmpRoot, 2, 0xfffffe2, 28); 89 addChar(tmpRoot, 3, 0xfffffe3, 28); 90 addChar(tmpRoot, 4, 0xfffffe4, 28); 91 addChar(tmpRoot, 5, 0xfffffe5, 28); 92 addChar(tmpRoot, 6, 0xfffffe6, 28); 93 addChar(tmpRoot, 7, 0xfffffe7, 28); 94 addChar(tmpRoot, 8, 0xfffffe8, 28); 95 addChar(tmpRoot, 9, 0xffffea, 24); 96 addChar(tmpRoot, 10, 0x3ffffffc, 30); 97 addChar(tmpRoot, 11, 0xfffffe9, 28); 98 addChar(tmpRoot, 12, 0xfffffea, 28); 99 addChar(tmpRoot, 13, 0x3ffffffd, 30); 100 addChar(tmpRoot, 14, 0xfffffeb, 28); 101 addChar(tmpRoot, 15, 0xfffffec, 28); 102 addChar(tmpRoot, 16, 0xfffffed, 28); 103 addChar(tmpRoot, 17, 0xfffffee, 28); 104 addChar(tmpRoot, 18, 0xfffffef, 28); 105 addChar(tmpRoot, 19, 0xffffff0, 28); 106 addChar(tmpRoot, 20, 0xffffff1, 28); 107 addChar(tmpRoot, 21, 0xffffff2, 28); 108 addChar(tmpRoot, 22, 0x3ffffffe, 30); 109 addChar(tmpRoot, 23, 0xffffff3, 28); 110 addChar(tmpRoot, 24, 0xffffff4, 28); 111 addChar(tmpRoot, 25, 0xffffff5, 28); 112 addChar(tmpRoot, 26, 0xffffff6, 28); 113 addChar(tmpRoot, 27, 0xffffff7, 28); 114 addChar(tmpRoot, 28, 0xffffff8, 28); 115 addChar(tmpRoot, 29, 0xffffff9, 28); 116 addChar(tmpRoot, 30, 0xffffffa, 28); 117 addChar(tmpRoot, 31, 0xffffffb, 28); 118 addChar(tmpRoot, 32, 0x14, 6); 119 addChar(tmpRoot, 33, 0x3f8, 10); 120 addChar(tmpRoot, 34, 0x3f9, 10); 121 addChar(tmpRoot, 35, 0xffa, 12); 122 addChar(tmpRoot, 36, 0x1ff9, 13); 123 addChar(tmpRoot, 37, 0x15, 6); 124 addChar(tmpRoot, 38, 0xf8, 8); 125 addChar(tmpRoot, 39, 0x7fa, 11); 126 addChar(tmpRoot, 40, 0x3fa, 10); 127 addChar(tmpRoot, 41, 0x3fb, 10); 128 addChar(tmpRoot, 42, 0xf9, 8); 129 addChar(tmpRoot, 43, 0x7fb, 11); 130 addChar(tmpRoot, 44, 0xfa, 8); 131 addChar(tmpRoot, 45, 0x16, 6); 132 addChar(tmpRoot, 46, 0x17, 6); 133 addChar(tmpRoot, 47, 0x18, 6); 134 addChar(tmpRoot, 48, 0x0, 5); 135 addChar(tmpRoot, 49, 0x1, 5); 136 addChar(tmpRoot, 50, 0x2, 5); 137 addChar(tmpRoot, 51, 0x19, 6); 138 addChar(tmpRoot, 52, 0x1a, 6); 139 addChar(tmpRoot, 53, 0x1b, 6); 140 addChar(tmpRoot, 54, 0x1c, 6); 141 addChar(tmpRoot, 55, 0x1d, 6); 142 addChar(tmpRoot, 56, 0x1e, 6); 143 addChar(tmpRoot, 57, 0x1f, 6); 144 addChar(tmpRoot, 58, 0x5c, 7); 145 addChar(tmpRoot, 59, 0xfb, 8); 146 addChar(tmpRoot, 60, 0x7ffc, 15); 147 addChar(tmpRoot, 61, 0x20, 6); 148 addChar(tmpRoot, 62, 0xffb, 12); 149 addChar(tmpRoot, 63, 0x3fc, 10); 150 addChar(tmpRoot, 64, 0x1ffa, 13); 151 addChar(tmpRoot, 65, 0x21, 6); 152 addChar(tmpRoot, 66, 0x5d, 7); 153 addChar(tmpRoot, 67, 0x5e, 7); 154 addChar(tmpRoot, 68, 0x5f, 7); 155 addChar(tmpRoot, 69, 0x60, 7); 156 addChar(tmpRoot, 70, 0x61, 7); 157 addChar(tmpRoot, 71, 0x62, 7); 158 addChar(tmpRoot, 72, 0x63, 7); 159 addChar(tmpRoot, 73, 0x64, 7); 160 addChar(tmpRoot, 74, 0x65, 7); 161 addChar(tmpRoot, 75, 0x66, 7); 162 addChar(tmpRoot, 76, 0x67, 7); 163 addChar(tmpRoot, 77, 0x68, 7); 164 addChar(tmpRoot, 78, 0x69, 7); 165 addChar(tmpRoot, 79, 0x6a, 7); 166 addChar(tmpRoot, 80, 0x6b, 7); 167 addChar(tmpRoot, 81, 0x6c, 7); 168 addChar(tmpRoot, 82, 0x6d, 7); 169 addChar(tmpRoot, 83, 0x6e, 7); 170 addChar(tmpRoot, 84, 0x6f, 7); 171 addChar(tmpRoot, 85, 0x70, 7); 172 addChar(tmpRoot, 86, 0x71, 7); 173 addChar(tmpRoot, 87, 0x72, 7); 174 addChar(tmpRoot, 88, 0xfc, 8); 175 addChar(tmpRoot, 89, 0x73, 7); 176 addChar(tmpRoot, 90, 0xfd, 8); 177 addChar(tmpRoot, 91, 0x1ffb, 13); 178 addChar(tmpRoot, 92, 0x7fff0, 19); 179 addChar(tmpRoot, 93, 0x1ffc, 13); 180 addChar(tmpRoot, 94, 0x3ffc, 14); 181 addChar(tmpRoot, 95, 0x22, 6); 182 addChar(tmpRoot, 96, 0x7ffd, 15); 183 addChar(tmpRoot, 97, 0x3, 5); 184 addChar(tmpRoot, 98, 0x23, 6); 185 addChar(tmpRoot, 99, 0x4, 5); 186 addChar(tmpRoot, 100, 0x24, 6); 187 addChar(tmpRoot, 101, 0x5, 5); 188 addChar(tmpRoot, 102, 0x25, 6); 189 addChar(tmpRoot, 103, 0x26, 6); 190 addChar(tmpRoot, 104, 0x27, 6); 191 addChar(tmpRoot, 105, 0x6, 5); 192 addChar(tmpRoot, 106, 0x74, 7); 193 addChar(tmpRoot, 107, 0x75, 7); 194 addChar(tmpRoot, 108, 0x28, 6); 195 addChar(tmpRoot, 109, 0x29, 6); 196 addChar(tmpRoot, 110, 0x2a, 6); 197 addChar(tmpRoot, 111, 0x7, 5); 198 addChar(tmpRoot, 112, 0x2b, 6); 199 addChar(tmpRoot, 113, 0x76, 7); 200 addChar(tmpRoot, 114, 0x2c, 6); 201 addChar(tmpRoot, 115, 0x8, 5); 202 addChar(tmpRoot, 116, 0x9, 5); 203 addChar(tmpRoot, 117, 0x2d, 6); 204 addChar(tmpRoot, 118, 0x77, 7); 205 addChar(tmpRoot, 119, 0x78, 7); 206 addChar(tmpRoot, 120, 0x79, 7); 207 addChar(tmpRoot, 121, 0x7a, 7); 208 addChar(tmpRoot, 122, 0x7b, 7); 209 addChar(tmpRoot, 123, 0x7ffe, 15); 210 addChar(tmpRoot, 124, 0x7fc, 11); 211 addChar(tmpRoot, 125, 0x3ffd, 14); 212 addChar(tmpRoot, 126, 0x1ffd, 13); 213 addChar(tmpRoot, 127, 0xffffffc, 28); 214 addChar(tmpRoot, 128, 0xfffe6, 20); 215 addChar(tmpRoot, 129, 0x3fffd2, 22); 216 addChar(tmpRoot, 130, 0xfffe7, 20); 217 addChar(tmpRoot, 131, 0xfffe8, 20); 218 addChar(tmpRoot, 132, 0x3fffd3, 22); 219 addChar(tmpRoot, 133, 0x3fffd4, 22); 220 addChar(tmpRoot, 134, 0x3fffd5, 22); 221 addChar(tmpRoot, 135, 0x7fffd9, 23); 222 addChar(tmpRoot, 136, 0x3fffd6, 22); 223 addChar(tmpRoot, 137, 0x7fffda, 23); 224 addChar(tmpRoot, 138, 0x7fffdb, 23); 225 addChar(tmpRoot, 139, 0x7fffdc, 23); 226 addChar(tmpRoot, 140, 0x7fffdd, 23); 227 addChar(tmpRoot, 141, 0x7fffde, 23); 228 addChar(tmpRoot, 142, 0xffffeb, 24); 229 addChar(tmpRoot, 143, 0x7fffdf, 23); 230 addChar(tmpRoot, 144, 0xffffec, 24); 231 addChar(tmpRoot, 145, 0xffffed, 24); 232 addChar(tmpRoot, 146, 0x3fffd7, 22); 233 addChar(tmpRoot, 147, 0x7fffe0, 23); 234 addChar(tmpRoot, 148, 0xffffee, 24); 235 addChar(tmpRoot, 149, 0x7fffe1, 23); 236 addChar(tmpRoot, 150, 0x7fffe2, 23); 237 addChar(tmpRoot, 151, 0x7fffe3, 23); 238 addChar(tmpRoot, 152, 0x7fffe4, 23); 239 addChar(tmpRoot, 153, 0x1fffdc, 21); 240 addChar(tmpRoot, 154, 0x3fffd8, 22); 241 addChar(tmpRoot, 155, 0x7fffe5, 23); 242 addChar(tmpRoot, 156, 0x3fffd9, 22); 243 addChar(tmpRoot, 157, 0x7fffe6, 23); 244 addChar(tmpRoot, 158, 0x7fffe7, 23); 245 addChar(tmpRoot, 159, 0xffffef, 24); 246 addChar(tmpRoot, 160, 0x3fffda, 22); 247 addChar(tmpRoot, 161, 0x1fffdd, 21); 248 addChar(tmpRoot, 162, 0xfffe9, 20); 249 addChar(tmpRoot, 163, 0x3fffdb, 22); 250 addChar(tmpRoot, 164, 0x3fffdc, 22); 251 addChar(tmpRoot, 165, 0x7fffe8, 23); 252 addChar(tmpRoot, 166, 0x7fffe9, 23); 253 addChar(tmpRoot, 167, 0x1fffde, 21); 254 addChar(tmpRoot, 168, 0x7fffea, 23); 255 addChar(tmpRoot, 169, 0x3fffdd, 22); 256 addChar(tmpRoot, 170, 0x3fffde, 22); 257 addChar(tmpRoot, 171, 0xfffff0, 24); 258 addChar(tmpRoot, 172, 0x1fffdf, 21); 259 addChar(tmpRoot, 173, 0x3fffdf, 22); 260 addChar(tmpRoot, 174, 0x7fffeb, 23); 261 addChar(tmpRoot, 175, 0x7fffec, 23); 262 addChar(tmpRoot, 176, 0x1fffe0, 21); 263 addChar(tmpRoot, 177, 0x1fffe1, 21); 264 addChar(tmpRoot, 178, 0x3fffe0, 22); 265 addChar(tmpRoot, 179, 0x1fffe2, 21); 266 addChar(tmpRoot, 180, 0x7fffed, 23); 267 addChar(tmpRoot, 181, 0x3fffe1, 22); 268 addChar(tmpRoot, 182, 0x7fffee, 23); 269 addChar(tmpRoot, 183, 0x7fffef, 23); 270 addChar(tmpRoot, 184, 0xfffea, 20); 271 addChar(tmpRoot, 185, 0x3fffe2, 22); 272 addChar(tmpRoot, 186, 0x3fffe3, 22); 273 addChar(tmpRoot, 187, 0x3fffe4, 22); 274 addChar(tmpRoot, 188, 0x7ffff0, 23); 275 addChar(tmpRoot, 189, 0x3fffe5, 22); 276 addChar(tmpRoot, 190, 0x3fffe6, 22); 277 addChar(tmpRoot, 191, 0x7ffff1, 23); 278 addChar(tmpRoot, 192, 0x3ffffe0, 26); 279 addChar(tmpRoot, 193, 0x3ffffe1, 26); 280 addChar(tmpRoot, 194, 0xfffeb, 20); 281 addChar(tmpRoot, 195, 0x7fff1, 19); 282 addChar(tmpRoot, 196, 0x3fffe7, 22); 283 addChar(tmpRoot, 197, 0x7ffff2, 23); 284 addChar(tmpRoot, 198, 0x3fffe8, 22); 285 addChar(tmpRoot, 199, 0x1ffffec, 25); 286 addChar(tmpRoot, 200, 0x3ffffe2, 26); 287 addChar(tmpRoot, 201, 0x3ffffe3, 26); 288 addChar(tmpRoot, 202, 0x3ffffe4, 26); 289 addChar(tmpRoot, 203, 0x7ffffde, 27); 290 addChar(tmpRoot, 204, 0x7ffffdf, 27); 291 addChar(tmpRoot, 205, 0x3ffffe5, 26); 292 addChar(tmpRoot, 206, 0xfffff1, 24); 293 addChar(tmpRoot, 207, 0x1ffffed, 25); 294 addChar(tmpRoot, 208, 0x7fff2, 19); 295 addChar(tmpRoot, 209, 0x1fffe3, 21); 296 addChar(tmpRoot, 210, 0x3ffffe6, 26); 297 addChar(tmpRoot, 211, 0x7ffffe0, 27); 298 addChar(tmpRoot, 212, 0x7ffffe1, 27); 299 addChar(tmpRoot, 213, 0x3ffffe7, 26); 300 addChar(tmpRoot, 214, 0x7ffffe2, 27); 301 addChar(tmpRoot, 215, 0xfffff2, 24); 302 addChar(tmpRoot, 216, 0x1fffe4, 21); 303 addChar(tmpRoot, 217, 0x1fffe5, 21); 304 addChar(tmpRoot, 218, 0x3ffffe8, 26); 305 addChar(tmpRoot, 219, 0x3ffffe9, 26); 306 addChar(tmpRoot, 220, 0xffffffd, 28); 307 addChar(tmpRoot, 221, 0x7ffffe3, 27); 308 addChar(tmpRoot, 222, 0x7ffffe4, 27); 309 addChar(tmpRoot, 223, 0x7ffffe5, 27); 310 addChar(tmpRoot, 224, 0xfffec, 20); 311 addChar(tmpRoot, 225, 0xfffff3, 24); 312 addChar(tmpRoot, 226, 0xfffed, 20); 313 addChar(tmpRoot, 227, 0x1fffe6, 21); 314 addChar(tmpRoot, 228, 0x3fffe9, 22); 315 addChar(tmpRoot, 229, 0x1fffe7, 21); 316 addChar(tmpRoot, 230, 0x1fffe8, 21); 317 addChar(tmpRoot, 231, 0x7ffff3, 23); 318 addChar(tmpRoot, 232, 0x3fffea, 22); 319 addChar(tmpRoot, 233, 0x3fffeb, 22); 320 addChar(tmpRoot, 234, 0x1ffffee, 25); 321 addChar(tmpRoot, 235, 0x1ffffef, 25); 322 addChar(tmpRoot, 236, 0xfffff4, 24); 323 addChar(tmpRoot, 237, 0xfffff5, 24); 324 addChar(tmpRoot, 238, 0x3ffffea, 26); 325 addChar(tmpRoot, 239, 0x7ffff4, 23); 326 addChar(tmpRoot, 240, 0x3ffffeb, 26); 327 addChar(tmpRoot, 241, 0x7ffffe6, 27); 328 addChar(tmpRoot, 242, 0x3ffffec, 26); 329 addChar(tmpRoot, 243, 0x3ffffed, 26); 330 addChar(tmpRoot, 244, 0x7ffffe7, 27); 331 addChar(tmpRoot, 245, 0x7ffffe8, 27); 332 addChar(tmpRoot, 246, 0x7ffffe9, 27); 333 addChar(tmpRoot, 247, 0x7ffffea, 27); 334 addChar(tmpRoot, 248, 0x7ffffeb, 27); 335 addChar(tmpRoot, 249, 0xffffffe, 28); 336 addChar(tmpRoot, 250, 0x7ffffec, 27); 337 addChar(tmpRoot, 251, 0x7ffffed, 27); 338 addChar(tmpRoot, 252, 0x7ffffee, 27); 339 addChar(tmpRoot, 253, 0x7ffffef, 27); 340 addChar(tmpRoot, 254, 0x7fffff0, 27); 341 addChar(tmpRoot, 255, 0x3ffffee, 26); 342 addEOS (tmpRoot, 256, EOS_LSB, EOS_LENGTH); 343 344 // The difference in performance can always be checked by not using 345 // the immutable trie: 346 // return tmpRoot; 347 return ImmutableNode.copyOf(tmpRoot); 348 } 349 QuickHuffman()350 private QuickHuffman() { } 351 addChar(Node root, int symbol, int code, int bitLength)352 private static void addChar(Node root, int symbol, int code, int bitLength) 353 { 354 addLeaf(root, (char) symbol, code, bitLength, false); 355 long value = ((long) code) << (64 - bitLength); // re-align MSB <- LSB 356 codes[symbol] = value | bitLength; 357 } 358 addEOS(Node root, int symbol, int code, int bitLength)359 private static void addEOS(Node root, int symbol, int code, int bitLength) 360 { 361 addLeaf(root, (char) symbol, code, bitLength, true); 362 } 363 addLeaf(Node root, char symbol, int code, int bitLength, boolean isEOS)364 private static void addLeaf(Node root, 365 char symbol, 366 int code, 367 int bitLength, 368 boolean isEOS) 369 { 370 assert 0 < bitLength && bitLength <= 32 : bitLength; 371 Node curr = root; 372 int nBytes = bytesForBits(bitLength); 373 // The number of bits the code needs to be shifted to the left in order 374 // to align with the byte #nBytes boundary: 375 int align = (nBytes << 3) - bitLength; 376 code <<= align; 377 // descend the trie until the last element 378 int l = 0; 379 for (int i = 0, probe = 0xff << ((nBytes - 1) << 3); 380 i < nBytes - 1; 381 i++, probe >>>= 8) 382 { 383 curr.setEOSPath(curr.isEOSPath() | isEOS); 384 int idx = (code & probe) >>> ((nBytes - 1 - i) << 3); 385 curr = curr.getOrCreateChild(idx); 386 curr.setLength(8); 387 l += 8; 388 } 389 // Assign the same char to all byte variants. For example, if the code 390 // and its length are 00011b and 5 respectively (letter 'a') then, in 391 // order to be able to match any byte starting with 00011b prefix, 392 // the following nodes need to be created: 393 // 394 // 00011000b, 00011001b, 00011010b, 00011011b, 00011100b, 00011101b, 395 // 00011110b and 00011111b 396 int idx = code & 0xff; 397 curr.setEOSPath(curr.isEOSPath() | isEOS); 398 for (int i = 0; i < (1 << align); i++) { 399 Node child = curr.getOrCreateChild(idx | i); 400 child.setSymbol(symbol); 401 child.setEOSPath(child.isEOSPath() | isEOS); 402 child.setLength(bitLength - l); 403 } 404 } 405 406 /* 407 * A node in the Huffman trie. 408 */ 409 interface Node { 410 411 boolean isEOSPath(); 412 413 void setEOSPath(boolean value); 414 415 boolean isLeaf(); 416 417 Node getChild(int index); 418 419 Node getOrCreateChild(int index); 420 421 Node[] getChildren(); 422 423 char getSymbol(); 424 425 void setSymbol(char symbol); 426 427 int getLength(); 428 429 void setLength(int value); 430 } 431 432 /* 433 * Mutable nodes used for initial construction of the Huffman trie. 434 * (These nodes are perfectly ok to be used after that.) 435 */ 436 static final class TemporaryNode implements Node { 437 438 private char symbol; 439 private boolean eosPath; 440 private TemporaryNode[] children; 441 private int length; 442 443 @Override 444 public TemporaryNode getOrCreateChild(int index) { 445 ensureChildrenExist(); 446 if (children[index] == null) { 447 children[index] = new TemporaryNode(); 448 } 449 return children[index]; 450 } 451 452 private void ensureChildrenExist() { 453 if (children == null) { 454 children = new TemporaryNode[256]; 455 } 456 } 457 458 @Override 459 public boolean isLeaf() { 460 return children == null; 461 } 462 463 @Override 464 public boolean isEOSPath() { 465 return eosPath; 466 } 467 468 @Override 469 public void setEOSPath(boolean value) { 470 eosPath = value; 471 } 472 473 @Override 474 public TemporaryNode getChild(int index) { 475 ensureChildrenExist(); 476 return children[index]; 477 } 478 479 @Override 480 public Node[] getChildren() { 481 if (children == null) { 482 return new Node[0]; 483 } 484 return children; 485 } 486 487 @Override 488 public char getSymbol() { 489 return symbol; 490 } 491 492 @Override 493 public int getLength() { 494 return length; 495 } 496 497 @Override 498 public void setSymbol(char value) { 499 this.symbol = value; 500 } 501 502 @Override 503 public void setLength(int value) { 504 this.length = value; 505 } 506 } 507 508 /* 509 * Immutable node used to construct traversal-only Huffman trie. 510 * 511 * Once the trie has been built, the support of modifications is no longer 512 * required. An immutable trie should be used. Not only it will help to 513 * catch possible bugs, but hopefully speedup the traversal operations. 514 */ 515 static final class ImmutableNode implements Node { 516 517 private final char symbol; 518 private final boolean eosPath; 519 private final int length; 520 private final List<ImmutableNode> children; 521 522 public static ImmutableNode copyOf(Node node) { 523 if (node.isLeaf()) { 524 return new ImmutableNode(node.getSymbol(), node.isEOSPath(), 525 node.getLength()); 526 } 527 Node[] children = node.getChildren(); 528 ImmutableNode[] immutableChildren = new ImmutableNode[children.length]; 529 for (int i = 0; i < children.length; i++) { 530 immutableChildren[i] = copyOf(children[i]); 531 } 532 return new ImmutableNode(node.isEOSPath(), node.getLength(), 533 immutableChildren); 534 } 535 536 /* Creates a leaf node */ 537 private ImmutableNode(char symbol, 538 boolean eosPath, 539 int length) { 540 this.symbol = symbol; 541 this.eosPath = eosPath; 542 this.length = length; 543 this.children = List.of(); 544 } 545 546 /* Creates a node with children */ 547 private ImmutableNode(boolean eosPath, 548 int length, 549 ImmutableNode[] children) 550 { 551 this.symbol = 0; 552 this.eosPath = eosPath; 553 this.length = length; 554 if (children.length == 0) { 555 throw new IllegalArgumentException(); 556 } 557 // A list produced by List.of should not be slower than array for 558 // accessing elements by index, and hopefully use additional 559 // optimizations (e.g. jdk.internal.vm.annotation.Stable) 560 this.children = List.of(children); 561 } 562 563 @Override 564 public boolean isLeaf() { 565 return children.isEmpty(); 566 } 567 568 @Override 569 public boolean isEOSPath() { 570 return eosPath; 571 } 572 573 @Override 574 public void setEOSPath(boolean value) { 575 throw new UnsupportedOperationException(); 576 } 577 578 @Override 579 public ImmutableNode getChild(int index) { 580 return children.get(index); 581 } 582 583 @Override 584 public ImmutableNode getOrCreateChild(int index) { 585 throw new UnsupportedOperationException(); 586 } 587 588 @Override 589 public ImmutableNode[] getChildren() { 590 // This method is not expected to be called on an immutable node. 591 // If it is called, it requires some investigation. 592 throw new UnsupportedOperationException(); 593 } 594 595 @Override 596 public char getSymbol() { 597 return symbol; 598 } 599 600 @Override 601 public void setSymbol(char symbol) { 602 throw new UnsupportedOperationException(); 603 } 604 605 @Override 606 public int getLength() { 607 return length; 608 } 609 610 @Override 611 public void setLength(int value) { 612 throw new UnsupportedOperationException(); 613 } 614 } 615 616 static final class Reader implements Huffman.Reader { 617 618 private final BufferUpdateConsumer UPDATER = 619 (buf, bufLen) -> { 620 buffer = buf; 621 bufferLen = bufLen; 622 }; 623 624 private Node curr = root; // current position in the trie 625 private long buffer; // bits left from the previous match (aligned to the left, or MSB) 626 private int bufferLen; // number of bits in the buffer 627 private int len; // length (in bits) of path to curr 628 private boolean done; 629 630 @Override 631 public void read(ByteBuffer source, 632 Appendable destination, 633 boolean isLast) throws IOException 634 { 635 while (!done) { 636 int remaining = source.remaining(); 637 int nBytes = HPACK.read(source, buffer, bufferLen, UPDATER); 638 // write as much as possible 639 while (true) { 640 if (bufferLen < 8) { 641 if (nBytes < remaining) { // read again 642 break; 643 } else if (!isLast) { // exit the method to accept more input 644 return; 645 } else if (bufferLen > 0) { // no more data is expected, pad 646 // (this padding may be done more than once) 647 buffer |= ((0xff00000000000000L >>> bufferLen) 648 & 0xff00000000000000L); 649 // do not update bufferLen, since all those ones are 650 // synthetic and are appended merely for the sake of 651 // lookup 652 } else { 653 done = true; 654 break; 655 } 656 } 657 int idx = (int) (buffer >>> 56); 658 Node node = curr.getChild(idx); 659 if (node == null) { // TODO: TEST 660 throw new IOException("Unexpected byte"); 661 } 662 if (node.isLeaf()) { 663 if (node.getLength() > bufferLen) { // matched more than we actually could (because of padding) 664 throw new IOException( 665 "Not a EOS prefix padding or unexpected end of data"); 666 } 667 if (node.isEOSPath()) { 668 throw new IOException("Encountered EOS"); 669 } 670 destination.append(node.getSymbol()); 671 curr = root; 672 len = 0; 673 } else { 674 curr = node; 675 // because of the padding, we can't match more bits than 676 // there are currently in the buffer 677 len += Math.min(bufferLen, node.getLength()); 678 } 679 buffer <<= node.getLength(); 680 bufferLen -= node.getLength(); 681 } 682 if (done && (curr.isEOSPath() && len > 7)) { 683 throw new IOException( 684 "Padding is too long (len=" + len + ") " 685 + "or unexpected end of data"); 686 } 687 } 688 } 689 690 @Override 691 public void reset() { 692 curr = root; 693 len = 0; 694 buffer = 0; 695 bufferLen = 0; 696 done = false; 697 } 698 } 699 700 static final class Writer implements Huffman.Writer { 701 702 private final BufferUpdateConsumer UPDATER = 703 (buf, bufLen) -> { 704 buffer = buf; 705 bufferLen = bufLen; 706 }; 707 708 private CharSequence source; 709 private boolean padded; 710 private int pos; 711 private int end; 712 private long buffer; 713 private int bufferLen; 714 715 @Override 716 public QuickHuffman.Writer from(CharSequence input, int start, int end) { 717 Objects.checkFromToIndex(start, end, input.length()); 718 this.pos = start; 719 this.end = end; 720 this.source = input; 721 return this; 722 } 723 724 @Override 725 public boolean write(ByteBuffer destination) { 726 while (true) { 727 while (true) { // stuff codes into long 728 if (pos >= end) { 729 break; 730 } 731 char c = source.charAt(pos); 732 if (c > 255) { 733 throw new IllegalArgumentException("char=" + ((int) c)); 734 } 735 long len = codeLengthOf(c); 736 if (bufferLen + len <= 64) { 737 buffer |= (codeValueOf(c) >>> bufferLen); // append 738 bufferLen += len; 739 pos++; 740 } else { 741 break; 742 } 743 } 744 if (bufferLen == 0) { 745 return true; 746 } 747 if (pos >= end && !padded) { // no more input chars are expected, pad 748 padded = true; 749 // A long shift to 64 will result in the same long, not 750 // necessarily 0L. In which case padding will be performed 751 // incorrectly. If bufferLen is equal to 64, the shift (and 752 // padding) in not performed. 753 // (see https://docs.oracle.com/javase/specs/jls/se10/html/jls-15.html#jls-15.19) 754 if (bufferLen != 64) { 755 buffer |= (EOS_MSB >>> bufferLen); 756 bufferLen = bytesForBits(bufferLen) << 3; 757 } 758 } 759 int nBytes = HPACK.write(buffer, bufferLen, UPDATER, destination); 760 if (nBytes == 0) { 761 return false; 762 } 763 } 764 } 765 766 @Override 767 public QuickHuffman.Writer reset() { 768 source = null; 769 buffer = 0; 770 bufferLen = 0; 771 end = 0; 772 pos = 0; 773 padded = false; 774 return this; 775 } 776 777 @Override 778 public int lengthOf(CharSequence value, int start, int end) { 779 int len = 0; 780 for (int i = start; i < end; i++) { 781 char c = value.charAt(i); 782 len += codeLengthOf(c); 783 } 784 return bytesForBits(len); 785 } 786 } 787 } 788