ceph/src/common/bit_vector.hpp

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2014 Red Hat <contact@redhat.com>
   7  *
   8  * LGPL2.1 (see COPYING-LGPL2.1) or later
   9  */
  10
  11 #ifndef BIT_VECTOR_HPP
  12 #define BIT_VECTOR_HPP
  13
  14 #include "common/Formatter.h"
  15 #include "include/ceph_assert.h"
  16 #include "include/encoding.h"
  17 #include <memory>
  18 #include <utility>
  19 #include <vector>
  20
  21 namespace ceph {
  22
  23 template <uint8_t _bit_count>
  24 class BitVector
  25 {
  26 private:
  27   static const uint8_t BITS_PER_BYTE = 8;
  28   static const uint32_t ELEMENTS_PER_BLOCK = BITS_PER_BYTE / _bit_count;
  29   static const uint8_t MASK = static_cast<uint8_t>((1 << _bit_count) - 1);
  30
  31   // must be power of 2
  32   BOOST_STATIC_ASSERT((_bit_count != 0) && !(_bit_count & (_bit_count - 1)));
  33   BOOST_STATIC_ASSERT(_bit_count <= BITS_PER_BYTE);
  34
  35   template <typename DataIterator>
  36   class ReferenceImpl {
  37   protected:
  38     DataIterator m_data_iterator;
  39     uint64_t m_shift;
  40
  41     ReferenceImpl(const DataIterator& data_iterator, uint64_t shift)
  42       : m_data_iterator(data_iterator), m_shift(shift) {
  43     }
  44     ReferenceImpl(DataIterator&& data_iterator, uint64_t shift)
  45       : m_data_iterator(std::move(data_iterator)), m_shift(shift) {
  46     }
  47
  48   public:
  49     inline operator uint8_t() const {
  50       return (*m_data_iterator >> m_shift) & MASK;
  51     }
  52   };
  53
  54 public:
  55
  56   class ConstReference : public ReferenceImpl<bufferlist::const_iterator> {
  57   private:
  58     friend class BitVector;
  59
  60     ConstReference(const bufferlist::const_iterator& data_iterator,
  61                    uint64_t shift)
  62       : ReferenceImpl<bufferlist::const_iterator>(data_iterator, shift) {
  63     }
  64     ConstReference(bufferlist::const_iterator&& data_iterator, uint64_t shift)
  65       : ReferenceImpl<bufferlist::const_iterator>(std::move(data_iterator),
  66                                                   shift) {
  67     }
  68   };
  69
  70   class Reference : public ReferenceImpl<bufferlist::iterator> {
  71   public:
  72     Reference& operator=(uint8_t v);
  73
  74   private:
  75     friend class BitVector;
  76
  77     Reference(const bufferlist::iterator& data_iterator, uint64_t shift)
  78       : ReferenceImpl<bufferlist::iterator>(data_iterator, shift) {
  79     }
  80     Reference(bufferlist::iterator&& data_iterator, uint64_t shift)
  81       : ReferenceImpl<bufferlist::iterator>(std::move(data_iterator), shift) {
  82     }
  83   };
  84
  85 public:
  86   template <typename BitVectorT, typename DataIterator>
  87   class IteratorImpl {
  88   private:
  89     friend class BitVector;
  90
  91     uint64_t m_offset = 0;
  92     BitVectorT *m_bit_vector;
  93
  94     // cached derived values
  95     uint64_t m_index = 0;
  96     uint64_t m_shift = 0;
  97     DataIterator m_data_iterator;
  98
  99     IteratorImpl(BitVectorT *bit_vector, uint64_t offset)
 100       : m_bit_vector(bit_vector),
 101         m_data_iterator(bit_vector->m_data.begin()) {
 102       *this += offset;
 103     }
 104
 105   public:
 106     inline IteratorImpl& operator++() {
 107       ++m_offset;
 108
 109       uint64_t index;
 110       compute_index(m_offset, &index, &m_shift);
 111
 112       ceph_assert(index == m_index || index == m_index + 1);
 113       if (index > m_index) {
 114         m_index = index;
 115         ++m_data_iterator;
 116       }
 117       return *this;
 118     }
 119     inline IteratorImpl& operator+=(uint64_t offset) {
 120       m_offset += offset;
 121       compute_index(m_offset, &m_index, &m_shift);
 122       if (m_offset < m_bit_vector->size()) {
 123         m_data_iterator.seek(m_index);
 124       } else {
 125         m_data_iterator = m_bit_vector->m_data.end();
 126       }
 127       return *this;
 128     }
 129
 130     inline IteratorImpl operator++(int) {
 131       IteratorImpl iterator_impl(*this);
 132       ++iterator_impl;
 133       return iterator_impl;
 134     }
 135     inline IteratorImpl operator+(uint64_t offset) {
 136       IteratorImpl iterator_impl(*this);
 137       iterator_impl += offset;
 138       return iterator_impl;
 139     }
 140
 141     inline bool operator==(const IteratorImpl& rhs) const {
 142       return (m_offset == rhs.m_offset && m_bit_vector == rhs.m_bit_vector);
 143     }
 144     inline bool operator!=(const IteratorImpl& rhs) const {
 145       return (m_offset != rhs.m_offset || m_bit_vector != rhs.m_bit_vector);
 146     }
 147
 148     inline ConstReference operator*() const {
 149       return ConstReference(m_data_iterator, m_shift);
 150     }
 151     inline Reference operator*() {
 152       return Reference(m_data_iterator, m_shift);
 153     }
 154   };
 155
 156   typedef IteratorImpl<const BitVector,
 157                        bufferlist::const_iterator> ConstIterator;
 158   typedef IteratorImpl<BitVector, bufferlist::iterator> Iterator;
 159
 160   static const uint32_t BLOCK_SIZE;
 161   static const uint8_t BIT_COUNT = _bit_count;
 162
 163   BitVector();
 164
 165   inline ConstIterator begin() const {
 166     return ConstIterator(this, 0);
 167   }
 168   inline ConstIterator end() const {
 169     return ConstIterator(this, m_size);
 170   }
 171   inline Iterator begin() {
 172     return Iterator(this, 0);
 173   }
 174   inline Iterator end() {
 175     return Iterator(this, m_size);
 176   }
 177
 178   void set_crc_enabled(bool enabled) {
 179     m_crc_enabled = enabled;
 180   }
 181   void clear();
 182
 183   void resize(uint64_t elements);
 184   uint64_t size() const;
 185
 186   const bufferlist& get_data() const;
 187
 188   Reference operator[](uint64_t offset);
 189   ConstReference operator[](uint64_t offset) const;
 190
 191   void encode_header(bufferlist& bl) const;
 192   void decode_header(bufferlist::const_iterator& it);
 193   uint64_t get_header_length() const;
 194
 195   void encode_data(bufferlist& bl, uint64_t data_byte_offset,
 196                    uint64_t byte_length) const;
 197   void decode_data(bufferlist::const_iterator& it, uint64_t data_byte_offset);
 198   void get_data_extents(uint64_t offset, uint64_t length,
 199                         uint64_t *data_byte_offset,
 200                         uint64_t *object_byte_offset,
 201                         uint64_t *byte_length) const;
 202
 203   void encode_footer(bufferlist& bl) const;
 204   void decode_footer(bufferlist::const_iterator& it);
 205   uint64_t get_footer_offset() const;
 206
 207   void decode_header_crc(bufferlist::const_iterator& it);
 208   void get_header_crc_extents(uint64_t *byte_offset,
 209                               uint64_t *byte_length) const;
 210
 211   void encode_data_crcs(bufferlist& bl, uint64_t offset,
 212                         uint64_t length) const;
 213   void decode_data_crcs(bufferlist::const_iterator& it, uint64_t offset);
 214   void get_data_crcs_extents(uint64_t offset, uint64_t length,
 215                              uint64_t *byte_offset,
 216                              uint64_t *byte_length) const;
 217
 218   void encode(bufferlist& bl) const;
 219   void decode(bufferlist::const_iterator& it);
 220   void dump(Formatter *f) const;
 221
 222   bool operator==(const BitVector &b) const;
 223
 224   static void generate_test_instances(std::list<BitVector *> &o);
 225 private:
 226   bufferlist m_data;
 227   uint64_t m_size;
 228   bool m_crc_enabled;
 229
 230   mutable __u32 m_header_crc;
 231
 232   // inhibit value-initialization when used in std::vector
 233   struct u32_struct {
 234     u32_struct() {}
 235     __u32 val;
 236   };
 237   mutable std::vector<u32_struct> m_data_crcs;
 238
 239   void resize(uint64_t elements, bool zero);
 240
 241   static void compute_index(uint64_t offset, uint64_t *index, uint64_t *shift);
 242
 243 };
 244
 245 template <uint8_t _b>
 246 const uint32_t BitVector<_b>::BLOCK_SIZE = 4096;
 247
 248 template <uint8_t _b>
 249 BitVector<_b>::BitVector() : m_size(0), m_crc_enabled(true), m_header_crc(0)
 250 {
 251 }
 252
 253 template <uint8_t _b>
 254 void BitVector<_b>::clear() {
 255   m_data.clear();
 256   m_data_crcs.clear();
 257   m_size = 0;
 258   m_header_crc = 0;
 259 }
 260
 261 template <uint8_t _b>
 262 void BitVector<_b>::resize(uint64_t size) {
 263   resize(size, true);
 264 }
 265
 266 template <uint8_t _b>
 267 void BitVector<_b>::resize(uint64_t size, bool zero) {
 268   uint64_t buffer_size = (size + ELEMENTS_PER_BLOCK - 1) / ELEMENTS_PER_BLOCK;
 269   if (buffer_size > m_data.length()) {
 270     if (zero) {
 271       m_data.append_zero(buffer_size - m_data.length());
 272     } else {
 273       m_data.append(buffer::ptr(buffer_size - m_data.length()));
 274     }
 275   } else if (buffer_size < m_data.length()) {
 276     bufferlist bl;
 277     bl.substr_of(m_data, 0, buffer_size);
 278     bl.swap(m_data);
 279   }
 280   m_size = size;
 281
 282   uint64_t block_count = (buffer_size + BLOCK_SIZE - 1) / BLOCK_SIZE;
 283   m_data_crcs.resize(block_count);
 284 }
 285
 286 template <uint8_t _b>
 287 uint64_t BitVector<_b>::size() const {
 288   return m_size;
 289 }
 290
 291 template <uint8_t _b>
 292 const bufferlist& BitVector<_b>::get_data() const {
 293   return m_data;
 294 }
 295
 296 template <uint8_t _b>
 297 void BitVector<_b>::compute_index(uint64_t offset, uint64_t *index, uint64_t *shift) {
 298   *index = offset / ELEMENTS_PER_BLOCK;
 299   *shift = ((ELEMENTS_PER_BLOCK - 1) - (offset % ELEMENTS_PER_BLOCK)) * _b;
 300 }
 301
 302 template <uint8_t _b>
 303 void BitVector<_b>::encode_header(bufferlist& bl) const {
 304   bufferlist header_bl;
 305   ENCODE_START(1, 1, header_bl);
 306   encode(m_size, header_bl);
 307   ENCODE_FINISH(header_bl);
 308   m_header_crc = header_bl.crc32c(0);
 309
 310   encode(header_bl, bl);
 311 }
 312
 313 template <uint8_t _b>
 314 void BitVector<_b>::decode_header(bufferlist::const_iterator& it) {
 315   using ceph::decode;
 316   bufferlist header_bl;
 317   decode(header_bl, it);
 318
 319   auto header_it = header_bl.cbegin();
 320   uint64_t size;
 321   DECODE_START(1, header_it);
 322   decode(size, header_it);
 323   DECODE_FINISH(header_it);
 324
 325   resize(size, false);
 326   m_header_crc = header_bl.crc32c(0);
 327 }
 328
 329 template <uint8_t _b>
 330 uint64_t BitVector<_b>::get_header_length() const {
 331   // 4 byte bl length, 6 byte encoding header, 8 byte size
 332   return 18;
 333 }
 334
 335 template <uint8_t _b>
 336 void BitVector<_b>::encode_data(bufferlist& bl, uint64_t data_byte_offset,
 337                                 uint64_t byte_length) const {
 338   ceph_assert(data_byte_offset % BLOCK_SIZE == 0);
 339   ceph_assert(data_byte_offset + byte_length == m_data.length() ||
 340               byte_length % BLOCK_SIZE == 0);
 341
 342   uint64_t end_offset = data_byte_offset + byte_length;
 343   while (data_byte_offset < end_offset) {
 344     uint64_t len = std::min<uint64_t>(BLOCK_SIZE,
 345                                       end_offset - data_byte_offset);
 346
 347     bufferlist bit;
 348     bit.substr_of(m_data, data_byte_offset, len);
 349     m_data_crcs[data_byte_offset / BLOCK_SIZE].val = bit.crc32c(0);
 350
 351     bl.claim_append(bit);
 352     data_byte_offset += BLOCK_SIZE;
 353   }
 354 }
 355
 356 template <uint8_t _b>
 357 void BitVector<_b>::decode_data(bufferlist::const_iterator& it,
 358                                 uint64_t data_byte_offset) {
 359   ceph_assert(data_byte_offset % BLOCK_SIZE == 0);
 360   if (it.end()) {
 361     return;
 362   }
 363
 364   uint64_t end_offset = data_byte_offset + it.get_remaining();
 365   if (end_offset > m_data.length()) {
 366     throw buffer::end_of_buffer();
 367   }
 368
 369   bufferlist data;
 370   if (data_byte_offset > 0) {
 371     data.substr_of(m_data, 0, data_byte_offset);
 372   }
 373
 374   while (data_byte_offset < end_offset) {
 375     uint64_t len = std::min<uint64_t>(BLOCK_SIZE, end_offset - data_byte_offset);
 376
 377     bufferptr ptr;
 378     it.copy_deep(len, ptr);
 379
 380     bufferlist bit;
 381     bit.append(ptr);
 382     if (m_crc_enabled &&
 383         m_data_crcs[data_byte_offset / BLOCK_SIZE].val != bit.crc32c(0)) {
 384       throw buffer::malformed_input("invalid data block CRC");
 385     }
 386     data.append(bit);
 387     data_byte_offset += bit.length();
 388   }
 389
 390   if (m_data.length() > end_offset) {
 391     bufferlist tail;
 392     tail.substr_of(m_data, end_offset, m_data.length() - end_offset);
 393     data.append(tail);
 394   }
 395   ceph_assert(data.length() == m_data.length());
 396   data.swap(m_data);
 397 }
 398
 399 template <uint8_t _b>
 400 void BitVector<_b>::get_data_extents(uint64_t offset, uint64_t length,
 401                                      uint64_t *data_byte_offset,
 402                                      uint64_t *object_byte_offset,
 403                                      uint64_t *byte_length) const {
 404   // read BLOCK_SIZE-aligned chunks
 405   ceph_assert(length > 0 && offset + length <= m_size);
 406   uint64_t shift;
 407   compute_index(offset, data_byte_offset, &shift);
 408   *data_byte_offset -= (*data_byte_offset % BLOCK_SIZE);
 409
 410   uint64_t end_offset;
 411   compute_index(offset + length - 1, &end_offset, &shift);
 412   end_offset += (BLOCK_SIZE - (end_offset % BLOCK_SIZE));
 413   ceph_assert(*data_byte_offset <= end_offset);
 414
 415   *object_byte_offset = get_header_length() + *data_byte_offset;
 416   *byte_length = end_offset - *data_byte_offset;
 417   if (*data_byte_offset + *byte_length > m_data.length()) {
 418     *byte_length = m_data.length() - *data_byte_offset;
 419   }
 420 }
 421
 422 template <uint8_t _b>
 423 void BitVector<_b>::encode_footer(bufferlist& bl) const {
 424   using ceph::encode;
 425   bufferlist footer_bl;
 426   if (m_crc_enabled) {
 427     encode(m_header_crc, footer_bl);
 428
 429     __u32 size = m_data_crcs.size();
 430     encode(size, footer_bl);
 431     encode_data_crcs(footer_bl, 0, m_size);
 432   }
 433   encode(footer_bl, bl);
 434 }
 435
 436 template <uint8_t _b>
 437 void BitVector<_b>::decode_footer(bufferlist::const_iterator& it) {
 438   using ceph::decode;
 439   bufferlist footer_bl;
 440   decode(footer_bl, it);
 441
 442   m_crc_enabled = (footer_bl.length() > 0);
 443   if (m_crc_enabled) {
 444     auto footer_it = footer_bl.cbegin();
 445     decode_header_crc(footer_it);
 446
 447     __u32 data_src_size;
 448     decode(data_src_size, footer_it);
 449     decode_data_crcs(footer_it, 0);
 450
 451     uint64_t block_count = (m_data.length() + BLOCK_SIZE - 1) / BLOCK_SIZE;
 452     if (m_data_crcs.size() != block_count) {
 453       throw buffer::malformed_input("invalid data block CRCs");
 454     }
 455   }
 456 }
 457
 458 template <uint8_t _b>
 459 uint64_t BitVector<_b>::get_footer_offset() const {
 460   return get_header_length() + m_data.length();
 461 }
 462
 463 template <uint8_t _b>
 464 void BitVector<_b>::decode_header_crc(bufferlist::const_iterator& it) {
 465   if (it.get_remaining() > 0) {
 466     __u32 header_crc;
 467     ceph::decode(header_crc, it);
 468     if (m_header_crc != header_crc) {
 469       throw buffer::malformed_input("incorrect header CRC");
 470     }
 471   }
 472 }
 473
 474 template <uint8_t _b>
 475 void BitVector<_b>::get_header_crc_extents(uint64_t *byte_offset,
 476                                            uint64_t *byte_length) const {
 477   // footer is prefixed with a bufferlist length
 478   *byte_offset = get_footer_offset() + sizeof(__u32);
 479   *byte_length = sizeof(__u32);
 480 }
 481
 482 template <uint8_t _b>
 483 void BitVector<_b>::encode_data_crcs(bufferlist& bl, uint64_t offset,
 484                                      uint64_t length) const {
 485   if (length == 0) {
 486     return;
 487   }
 488
 489   uint64_t index;
 490   uint64_t shift;
 491   compute_index(offset, &index, &shift);
 492   uint64_t crc_index = index / BLOCK_SIZE;
 493
 494   compute_index(offset + length - 1, &index, &shift);
 495   uint64_t end_crc_index = index / BLOCK_SIZE;
 496   while (crc_index <= end_crc_index) {
 497     __u32 crc = m_data_crcs[crc_index++].val;
 498     ceph::encode(crc, bl);
 499   }
 500 }
 501
 502 template <uint8_t _b>
 503 void BitVector<_b>::decode_data_crcs(bufferlist::const_iterator& it,
 504                                      uint64_t offset) {
 505   if (it.end()) {
 506     return;
 507   }
 508
 509   uint64_t index;
 510   uint64_t shift;
 511   compute_index(offset, &index, &shift);
 512
 513   uint64_t crc_index = index / BLOCK_SIZE;
 514   uint64_t remaining = it.get_remaining() / sizeof(__u32);
 515   while (remaining > 0) {
 516     __u32 crc;
 517     ceph::decode(crc, it);
 518     m_data_crcs[crc_index++].val = crc;
 519     --remaining;
 520   }
 521 }
 522
 523 template <uint8_t _b>
 524 void BitVector<_b>::get_data_crcs_extents(uint64_t offset, uint64_t length,
 525                                           uint64_t *byte_offset,
 526                                           uint64_t *byte_length) const {
 527   // data CRCs immediately follow the header CRC
 528   get_header_crc_extents(byte_offset, byte_length);
 529   *byte_offset += *byte_length;
 530
 531   // skip past data CRC vector size
 532   *byte_offset += sizeof(__u32);
 533
 534   // CRCs are computed over BLOCK_SIZE chunks
 535   ceph_assert(length > 0 && offset + length <= m_size);
 536   uint64_t index;
 537   uint64_t shift;
 538   compute_index(offset, &index, &shift);
 539   uint64_t start_byte_offset =
 540     *byte_offset + ((index / BLOCK_SIZE) * sizeof(__u32));
 541
 542   compute_index(offset + length, &index, &shift);
 543   uint64_t end_byte_offset =
 544     *byte_offset + (((index / BLOCK_SIZE) + 1) * sizeof(__u32));
 545   ceph_assert(start_byte_offset < end_byte_offset);
 546
 547   *byte_offset = start_byte_offset;
 548   *byte_length = end_byte_offset - start_byte_offset;
 549 }
 550
 551 template <uint8_t _b>
 552 void BitVector<_b>::encode(bufferlist& bl) const {
 553   encode_header(bl);
 554   encode_data(bl, 0, m_data.length());
 555   encode_footer(bl);
 556 }
 557
 558 template <uint8_t _b>
 559 void BitVector<_b>::decode(bufferlist::const_iterator& it) {
 560   decode_header(it);
 561
 562   bufferlist data_bl;
 563   if (m_data.length() > 0) {
 564     it.copy(m_data.length(), data_bl);
 565   }
 566
 567   decode_footer(it);
 568
 569   auto data_it = data_bl.cbegin();
 570   decode_data(data_it, 0);
 571 }
 572
 573 template <uint8_t _b>
 574 void BitVector<_b>::dump(Formatter *f) const {
 575   f->dump_unsigned("size", m_size);
 576   f->open_array_section("bit_table");
 577   for (unsigned i = 0; i < m_data.length(); ++i) {
 578     f->dump_format("byte", "0x%02hhX", m_data[i]);
 579   }
 580   f->close_section();
 581 }
 582
 583 template <uint8_t _b>
 584 bool BitVector<_b>::operator==(const BitVector &b) const {
 585   return (this->m_size == b.m_size && this->m_data == b.m_data);
 586 }
 587
 588 template <uint8_t _b>
 589 typename BitVector<_b>::Reference BitVector<_b>::operator[](uint64_t offset) {
 590   uint64_t index;
 591   uint64_t shift;
 592   compute_index(offset, &index, &shift);
 593
 594   bufferlist::iterator data_iterator(m_data.begin());
 595   data_iterator.seek(index);
 596   return Reference(std::move(data_iterator), shift);
 597 }
 598
 599 template <uint8_t _b>
 600 typename BitVector<_b>::ConstReference BitVector<_b>::operator[](uint64_t offset) const {
 601   uint64_t index;
 602   uint64_t shift;
 603   compute_index(offset, &index, &shift);
 604
 605   bufferlist::const_iterator data_iterator(m_data.begin());
 606   data_iterator.seek(index);
 607   return ConstReference(std::move(data_iterator), shift);
 608 }
 609
 610 template <uint8_t _b>
 611 typename BitVector<_b>::Reference& BitVector<_b>::Reference::operator=(uint8_t v) {
 612   uint8_t mask = MASK << this->m_shift;
 613   char packed_value = (*this->m_data_iterator & ~mask) |
 614                       ((v << this->m_shift) & mask);
 615   bufferlist::iterator it(this->m_data_iterator);
 616   it.copy_in(1, &packed_value, true);
 617   return *this;
 618 }
 619
 620 template <uint8_t _b>
 621 void BitVector<_b>::generate_test_instances(std::list<BitVector *> &o) {
 622   o.push_back(new BitVector());
 623
 624   BitVector *b = new BitVector();
 625   const uint64_t radix = 1 << b->BIT_COUNT;
 626   const uint64_t size = 1024;
 627
 628   b->resize(size, false);
 629   for (uint64_t i = 0; i < size; ++i) {
 630     (*b)[i] = rand() % radix;
 631   }
 632   o.push_back(b);
 633 }
 634
 635
 636 WRITE_CLASS_ENCODER(ceph::BitVector<2>)
 637
 638 template <uint8_t _b>
 639 inline std::ostream& operator<<(std::ostream& out, const ceph::BitVector<_b> &b)
 640 {
 641   out << "ceph::BitVector<" << _b << ">(size=" << b.size() << ", data="
 642       << b.get_data() << ")";
 643   return out;
 644 }
 645 }
 646
 647 #endif // BIT_VECTOR_HPP