This file is indexed.

/usr/include/tbb/concurrent_hash_map.h is in libtbb-dev 4.2~20130725-1.1ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
/*
    Copyright 2005-2013 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks 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 for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#ifndef __TBB_concurrent_hash_map_H
#define __TBB_concurrent_hash_map_H

#include "tbb_stddef.h"

#if !TBB_USE_EXCEPTIONS && _MSC_VER
    // Suppress "C++ exception handler used, but unwind semantics are not enabled" warning in STL headers
    #pragma warning (push)
    #pragma warning (disable: 4530)
#endif

#include <iterator>
#include <utility>      // Need std::pair
#include <cstring>      // Need std::memset

#if !TBB_USE_EXCEPTIONS && _MSC_VER
    #pragma warning (pop)
#endif

#include "cache_aligned_allocator.h"
#include "tbb_allocator.h"
#include "spin_rw_mutex.h"
#include "atomic.h"
#include "aligned_space.h"
#include "tbb_exception.h"
#include "tbb_profiling.h"
#include "internal/_concurrent_unordered_impl.h" // Need tbb_hasher
#if __TBB_INITIALIZER_LISTS_PRESENT
#include <initializer_list>
#endif
#if TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
#include <typeinfo>
#endif
#if __TBB_STATISTICS
#include <stdio.h>
#endif

namespace tbb {

//! hash_compare that is default argument for concurrent_hash_map
template<typename Key>
struct tbb_hash_compare {
    static size_t hash( const Key& a ) { return tbb_hasher(a); }
    static bool equal( const Key& a, const Key& b ) { return a == b; }
};

namespace interface5 {

    template<typename Key, typename T, typename HashCompare = tbb_hash_compare<Key>, typename A = tbb_allocator<std::pair<Key, T> > >
    class concurrent_hash_map;

    //! @cond INTERNAL
    namespace internal {
    using namespace tbb::internal;


    //! Type of a hash code.
    typedef size_t hashcode_t;
    //! Node base type
    struct hash_map_node_base : tbb::internal::no_copy {
        //! Mutex type
        typedef spin_rw_mutex mutex_t;
        //! Scoped lock type for mutex
        typedef mutex_t::scoped_lock scoped_t;
        //! Next node in chain
        hash_map_node_base *next;
        mutex_t mutex;
    };
    //! Incompleteness flag value
    static hash_map_node_base *const rehash_req = reinterpret_cast<hash_map_node_base*>(size_t(3));
    //! Rehashed empty bucket flag
    static hash_map_node_base *const empty_rehashed = reinterpret_cast<hash_map_node_base*>(size_t(0));
    //! base class of concurrent_hash_map
    class hash_map_base {
    public:
        //! Size type
        typedef size_t size_type;
        //! Type of a hash code.
        typedef size_t hashcode_t;
        //! Segment index type
        typedef size_t segment_index_t;
        //! Node base type
        typedef hash_map_node_base node_base;
        //! Bucket type
        struct bucket : tbb::internal::no_copy {
            //! Mutex type for buckets
            typedef spin_rw_mutex mutex_t;
            //! Scoped lock type for mutex
            typedef mutex_t::scoped_lock scoped_t;
            mutex_t mutex;
            node_base *node_list;
        };
        //! Count of segments in the first block
        static size_type const embedded_block = 1;
        //! Count of segments in the first block
        static size_type const embedded_buckets = 1<<embedded_block;
        //! Count of segments in the first block
        static size_type const first_block = 8; //including embedded_block. perfect with bucket size 16, so the allocations are power of 4096
        //! Size of a pointer / table size
        static size_type const pointers_per_table = sizeof(segment_index_t) * 8; // one segment per bit
        //! Segment pointer
        typedef bucket *segment_ptr_t;
        //! Segment pointers table type
        typedef segment_ptr_t segments_table_t[pointers_per_table];
        //! Hash mask = sum of allocated segment sizes - 1
        atomic<hashcode_t> my_mask;
        //! Segment pointers table. Also prevents false sharing between my_mask and my_size
        segments_table_t my_table;
        //! Size of container in stored items
        atomic<size_type> my_size; // It must be in separate cache line from my_mask due to performance effects
        //! Zero segment
        bucket my_embedded_segment[embedded_buckets];
#if __TBB_STATISTICS
        atomic<unsigned> my_info_resizes; // concurrent ones
        mutable atomic<unsigned> my_info_restarts; // race collisions
        atomic<unsigned> my_info_rehashes;  // invocations of rehash_bucket
#endif
        //! Constructor
        hash_map_base() {
            std::memset( this, 0, pointers_per_table*sizeof(segment_ptr_t) // 32*4=128   or 64*8=512
                + sizeof(my_size) + sizeof(my_mask)  // 4+4 or 8+8
                + embedded_buckets*sizeof(bucket) ); // n*8 or n*16
            for( size_type i = 0; i < embedded_block; i++ ) // fill the table
                my_table[i] = my_embedded_segment + segment_base(i);
            my_mask = embedded_buckets - 1;
            __TBB_ASSERT( embedded_block <= first_block, "The first block number must include embedded blocks");
#if __TBB_STATISTICS
            my_info_resizes = 0; // concurrent ones
            my_info_restarts = 0; // race collisions
            my_info_rehashes = 0;  // invocations of rehash_bucket
#endif
        }

        //! @return segment index of given index in the array
        static segment_index_t segment_index_of( size_type index ) {
            return segment_index_t( __TBB_Log2( index|1 ) );
        }

        //! @return the first array index of given segment
        static segment_index_t segment_base( segment_index_t k ) {
            return (segment_index_t(1)<<k & ~segment_index_t(1));
        }

        //! @return segment size except for @arg k == 0
        static size_type segment_size( segment_index_t k ) {
            return size_type(1)<<k; // fake value for k==0
        }

        //! @return true if @arg ptr is valid pointer
        static bool is_valid( void *ptr ) {
            return reinterpret_cast<uintptr_t>(ptr) > uintptr_t(63);
        }

        //! Initialize buckets
        static void init_buckets( segment_ptr_t ptr, size_type sz, bool is_initial ) {
            if( is_initial ) std::memset(ptr, 0, sz*sizeof(bucket) );
            else for(size_type i = 0; i < sz; i++, ptr++) {
                *reinterpret_cast<intptr_t*>(&ptr->mutex) = 0;
                ptr->node_list = rehash_req;
            }
        }

        //! Add node @arg n to bucket @arg b
        static void add_to_bucket( bucket *b, node_base *n ) {
            __TBB_ASSERT(b->node_list != rehash_req, NULL);
            n->next = b->node_list;
            b->node_list = n; // its under lock and flag is set
        }

        //! Exception safety helper
        struct enable_segment_failsafe : tbb::internal::no_copy {
            segment_ptr_t *my_segment_ptr;
            enable_segment_failsafe(segments_table_t &table, segment_index_t k) : my_segment_ptr(&table[k]) {}
            ~enable_segment_failsafe() {
                if( my_segment_ptr ) *my_segment_ptr = 0; // indicate no allocation in progress
            }
        };

        //! Enable segment
        void enable_segment( segment_index_t k, bool is_initial = false ) {
            __TBB_ASSERT( k, "Zero segment must be embedded" );
            enable_segment_failsafe watchdog( my_table, k );
            cache_aligned_allocator<bucket> alloc;
            size_type sz;
            __TBB_ASSERT( !is_valid(my_table[k]), "Wrong concurrent assignment");
            if( k >= first_block ) {
                sz = segment_size( k );
                segment_ptr_t ptr = alloc.allocate( sz );
                init_buckets( ptr, sz, is_initial );
                itt_hide_store_word( my_table[k], ptr );
                sz <<= 1;// double it to get entire capacity of the container
            } else { // the first block
                __TBB_ASSERT( k == embedded_block, "Wrong segment index" );
                sz = segment_size( first_block );
                segment_ptr_t ptr = alloc.allocate( sz - embedded_buckets );
                init_buckets( ptr, sz - embedded_buckets, is_initial );
                ptr -= segment_base(embedded_block);
                for(segment_index_t i = embedded_block; i < first_block; i++) // calc the offsets
                    itt_hide_store_word( my_table[i], ptr + segment_base(i) );
            }
            itt_store_word_with_release( my_mask, sz-1 );
            watchdog.my_segment_ptr = 0;
        }

        //! Get bucket by (masked) hashcode
        bucket *get_bucket( hashcode_t h ) const throw() { // TODO: add throw() everywhere?
            segment_index_t s = segment_index_of( h );
            h -= segment_base(s);
            segment_ptr_t seg = my_table[s];
            __TBB_ASSERT( is_valid(seg), "hashcode must be cut by valid mask for allocated segments" );
            return &seg[h];
        }

        // internal serial rehashing helper
        void mark_rehashed_levels( hashcode_t h ) throw () {
            segment_index_t s = segment_index_of( h );
            while( segment_ptr_t seg = my_table[++s] )
                if( seg[h].node_list == rehash_req ) {
                    seg[h].node_list = empty_rehashed;
                    mark_rehashed_levels( h + ((hashcode_t)1<<s) ); // optimized segment_base(s)
                }
        }

        //! Check for mask race
        // Splitting into two functions should help inlining
        inline bool check_mask_race( const hashcode_t h, hashcode_t &m ) const {
            hashcode_t m_now, m_old = m;
            m_now = (hashcode_t) itt_load_word_with_acquire( my_mask );
            if( m_old != m_now )
                return check_rehashing_collision( h, m_old, m = m_now );
            return false;
        }

        //! Process mask race, check for rehashing collision
        bool check_rehashing_collision( const hashcode_t h, hashcode_t m_old, hashcode_t m ) const {
            __TBB_ASSERT(m_old != m, NULL); // TODO?: m arg could be optimized out by passing h = h&m
            if( (h & m_old) != (h & m) ) { // mask changed for this hashcode, rare event
                // condition above proves that 'h' has some other bits set beside 'm_old'
                // find next applicable mask after m_old    //TODO: look at bsl instruction
                for( ++m_old; !(h & m_old); m_old <<= 1 ) // at maximum few rounds depending on the first block size
                    ;
                m_old = (m_old<<1) - 1; // get full mask from a bit
                __TBB_ASSERT((m_old&(m_old+1))==0 && m_old <= m, NULL);
                // check whether it is rehashing/ed
                if( itt_load_word_with_acquire(get_bucket(h & m_old)->node_list) != rehash_req )
                {
#if __TBB_STATISTICS
                    my_info_restarts++; // race collisions
#endif
                    return true;
                }
            }
            return false;
        }

        //! Insert a node and check for load factor. @return segment index to enable.
        segment_index_t insert_new_node( bucket *b, node_base *n, hashcode_t mask ) {
            size_type sz = ++my_size; // prefix form is to enforce allocation after the first item inserted
            add_to_bucket( b, n );
            // check load factor
            if( sz >= mask ) { // TODO: add custom load_factor
                segment_index_t new_seg = __TBB_Log2( mask+1 ); //optimized segment_index_of
                __TBB_ASSERT( is_valid(my_table[new_seg-1]), "new allocations must not publish new mask until segment has allocated");
                static const segment_ptr_t is_allocating = (segment_ptr_t)2;
                if( !itt_hide_load_word(my_table[new_seg])
                  && as_atomic(my_table[new_seg]).compare_and_swap(is_allocating, NULL) == NULL )
                    return new_seg; // The value must be processed
            }
            return 0;
        }

        //! Prepare enough segments for number of buckets
        void reserve(size_type buckets) {
            if( !buckets-- ) return;
            bool is_initial = !my_size;
            for( size_type m = my_mask; buckets > m; m = my_mask )
                enable_segment( segment_index_of( m+1 ), is_initial );
        }
        //! Swap hash_map_bases
        void internal_swap(hash_map_base &table) {
            std::swap(this->my_mask, table.my_mask);
            std::swap(this->my_size, table.my_size);
            for(size_type i = 0; i < embedded_buckets; i++)
                std::swap(this->my_embedded_segment[i].node_list, table.my_embedded_segment[i].node_list);
            for(size_type i = embedded_block; i < pointers_per_table; i++)
                std::swap(this->my_table[i], table.my_table[i]);
        }
    };

    template<typename Iterator>
    class hash_map_range;

    //! Meets requirements of a forward iterator for STL */
    /** Value is either the T or const T type of the container.
        @ingroup containers */
    template<typename Container, typename Value>
    class hash_map_iterator
        : public std::iterator<std::forward_iterator_tag,Value>
    {
        typedef Container map_type;
        typedef typename Container::node node;
        typedef hash_map_base::node_base node_base;
        typedef hash_map_base::bucket bucket;

        template<typename C, typename T, typename U>
        friend bool operator==( const hash_map_iterator<C,T>& i, const hash_map_iterator<C,U>& j );

        template<typename C, typename T, typename U>
        friend bool operator!=( const hash_map_iterator<C,T>& i, const hash_map_iterator<C,U>& j );

        template<typename C, typename T, typename U>
        friend ptrdiff_t operator-( const hash_map_iterator<C,T>& i, const hash_map_iterator<C,U>& j );

        template<typename C, typename U>
        friend class hash_map_iterator;

        template<typename I>
        friend class hash_map_range;

        void advance_to_next_bucket() { // TODO?: refactor to iterator_base class
            size_t k = my_index+1;
            while( my_bucket && k <= my_map->my_mask ) {
                // Following test uses 2's-complement wizardry
                if( k& (k-2) ) // not the beginning of a segment
                    ++my_bucket;
                else my_bucket = my_map->get_bucket( k );
                my_node = static_cast<node*>( my_bucket->node_list );
                if( hash_map_base::is_valid(my_node) ) {
                    my_index = k; return;
                }
                ++k;
            }
            my_bucket = 0; my_node = 0; my_index = k; // the end
        }
#if !defined(_MSC_VER) || defined(__INTEL_COMPILER)
        template<typename Key, typename T, typename HashCompare, typename A>
        friend class interface5::concurrent_hash_map;
#else
    public: // workaround
#endif
        //! concurrent_hash_map over which we are iterating.
        const Container *my_map;

        //! Index in hash table for current item
        size_t my_index;

        //! Pointer to bucket
        const bucket *my_bucket;

        //! Pointer to node that has current item
        node *my_node;

        hash_map_iterator( const Container &map, size_t index, const bucket *b, node_base *n );

    public:
        //! Construct undefined iterator
        hash_map_iterator() {}
        hash_map_iterator( const hash_map_iterator<Container,typename Container::value_type> &other ) :
            my_map(other.my_map),
            my_index(other.my_index),
            my_bucket(other.my_bucket),
            my_node(other.my_node)
        {}
        Value& operator*() const {
            __TBB_ASSERT( hash_map_base::is_valid(my_node), "iterator uninitialized or at end of container?" );
            return my_node->item;
        }
        Value* operator->() const {return &operator*();}
        hash_map_iterator& operator++();

        //! Post increment
        hash_map_iterator operator++(int) {
            hash_map_iterator old(*this);
            operator++();
            return old;
        }
    };

    template<typename Container, typename Value>
    hash_map_iterator<Container,Value>::hash_map_iterator( const Container &map, size_t index, const bucket *b, node_base *n ) :
        my_map(&map),
        my_index(index),
        my_bucket(b),
        my_node( static_cast<node*>(n) )
    {
        if( b && !hash_map_base::is_valid(n) )
            advance_to_next_bucket();
    }

    template<typename Container, typename Value>
    hash_map_iterator<Container,Value>& hash_map_iterator<Container,Value>::operator++() {
        my_node = static_cast<node*>( my_node->next );
        if( !my_node ) advance_to_next_bucket();
        return *this;
    }

    template<typename Container, typename T, typename U>
    bool operator==( const hash_map_iterator<Container,T>& i, const hash_map_iterator<Container,U>& j ) {
        return i.my_node == j.my_node && i.my_map == j.my_map;
    }

    template<typename Container, typename T, typename U>
    bool operator!=( const hash_map_iterator<Container,T>& i, const hash_map_iterator<Container,U>& j ) {
        return i.my_node != j.my_node || i.my_map != j.my_map;
    }

    //! Range class used with concurrent_hash_map
    /** @ingroup containers */
    template<typename Iterator>
    class hash_map_range {
        typedef typename Iterator::map_type map_type;
        Iterator my_begin;
        Iterator my_end;
        mutable Iterator my_midpoint;
        size_t my_grainsize;
        //! Set my_midpoint to point approximately half way between my_begin and my_end.
        void set_midpoint() const;
        template<typename U> friend class hash_map_range;
    public:
        //! Type for size of a range
        typedef std::size_t size_type;
        typedef typename Iterator::value_type value_type;
        typedef typename Iterator::reference reference;
        typedef typename Iterator::difference_type difference_type;
        typedef Iterator iterator;

        //! True if range is empty.
        bool empty() const {return my_begin==my_end;}

        //! True if range can be partitioned into two subranges.
        bool is_divisible() const {
            return my_midpoint!=my_end;
        }
        //! Split range.
        hash_map_range( hash_map_range& r, split ) :
            my_end(r.my_end),
            my_grainsize(r.my_grainsize)
        {
            r.my_end = my_begin = r.my_midpoint;
            __TBB_ASSERT( !empty(), "Splitting despite the range is not divisible" );
            __TBB_ASSERT( !r.empty(), "Splitting despite the range is not divisible" );
            set_midpoint();
            r.set_midpoint();
        }
        //! type conversion
        template<typename U>
        hash_map_range( hash_map_range<U>& r) :
            my_begin(r.my_begin),
            my_end(r.my_end),
            my_midpoint(r.my_midpoint),
            my_grainsize(r.my_grainsize)
        {}
#if TBB_DEPRECATED
        //! Init range with iterators and grainsize specified
        hash_map_range( const Iterator& begin_, const Iterator& end_, size_type grainsize_ = 1 ) :
            my_begin(begin_),
            my_end(end_),
            my_grainsize(grainsize_)
        {
            if(!my_end.my_index && !my_end.my_bucket) // end
                my_end.my_index = my_end.my_map->my_mask + 1;
            set_midpoint();
            __TBB_ASSERT( grainsize_>0, "grainsize must be positive" );
        }
#endif
        //! Init range with container and grainsize specified
        hash_map_range( const map_type &map, size_type grainsize_ = 1 ) :
            my_begin( Iterator( map, 0, map.my_embedded_segment, map.my_embedded_segment->node_list ) ),
            my_end( Iterator( map, map.my_mask + 1, 0, 0 ) ),
            my_grainsize( grainsize_ )
        {
            __TBB_ASSERT( grainsize_>0, "grainsize must be positive" );
            set_midpoint();
        }
        const Iterator& begin() const {return my_begin;}
        const Iterator& end() const {return my_end;}
        //! The grain size for this range.
        size_type grainsize() const {return my_grainsize;}
    };

    template<typename Iterator>
    void hash_map_range<Iterator>::set_midpoint() const {
        // Split by groups of nodes
        size_t m = my_end.my_index-my_begin.my_index;
        if( m > my_grainsize ) {
            m = my_begin.my_index + m/2u;
            hash_map_base::bucket *b = my_begin.my_map->get_bucket(m);
            my_midpoint = Iterator(*my_begin.my_map,m,b,b->node_list);
        } else {
            my_midpoint = my_end;
        }
        __TBB_ASSERT( my_begin.my_index <= my_midpoint.my_index,
            "my_begin is after my_midpoint" );
        __TBB_ASSERT( my_midpoint.my_index <= my_end.my_index,
            "my_midpoint is after my_end" );
        __TBB_ASSERT( my_begin != my_midpoint || my_begin == my_end,
            "[my_begin, my_midpoint) range should not be empty" );
    }

    } // internal
//! @endcond

//! Unordered map from Key to T.
/** concurrent_hash_map is associative container with concurrent access.

@par Compatibility
    The class meets all Container Requirements from C++ Standard (See ISO/IEC 14882:2003(E), clause 23.1).

@par Exception Safety
    - Hash function is not permitted to throw an exception. User-defined types Key and T are forbidden from throwing an exception in destructors.
    - If exception happens during insert() operations, it has no effect (unless exception raised by HashCompare::hash() function during grow_segment).
    - If exception happens during operator=() operation, the container can have a part of source items, and methods size() and empty() can return wrong results.

@par Changes since TBB 2.1
    - Replaced internal algorithm and data structure. Patent is pending.
    - Added buckets number argument for constructor

@par Changes since TBB 2.0
    - Fixed exception-safety
    - Added template argument for allocator
    - Added allocator argument in constructors
    - Added constructor from a range of iterators
    - Added several new overloaded insert() methods
    - Added get_allocator()
    - Added swap()
    - Added count()
    - Added overloaded erase(accessor &) and erase(const_accessor&)
    - Added equal_range() [const]
    - Added [const_]pointer, [const_]reference, and allocator_type types
    - Added global functions: operator==(), operator!=(), and swap()

    @ingroup containers */
template<typename Key, typename T, typename HashCompare, typename Allocator>
class concurrent_hash_map : protected internal::hash_map_base {
    template<typename Container, typename Value>
    friend class internal::hash_map_iterator;

    template<typename I>
    friend class internal::hash_map_range;

public:
    typedef Key key_type;
    typedef T mapped_type;
    typedef std::pair<const Key,T> value_type;
    typedef hash_map_base::size_type size_type;
    typedef ptrdiff_t difference_type;
    typedef value_type *pointer;
    typedef const value_type *const_pointer;
    typedef value_type &reference;
    typedef const value_type &const_reference;
    typedef internal::hash_map_iterator<concurrent_hash_map,value_type> iterator;
    typedef internal::hash_map_iterator<concurrent_hash_map,const value_type> const_iterator;
    typedef internal::hash_map_range<iterator> range_type;
    typedef internal::hash_map_range<const_iterator> const_range_type;
    typedef Allocator allocator_type;

protected:
    friend class const_accessor;
    struct node;
    typedef typename Allocator::template rebind<node>::other node_allocator_type;
    node_allocator_type my_allocator;
    HashCompare my_hash_compare;

    struct node : public node_base {
        value_type item;
        node( const Key &key ) : item(key, T()) {}
        node( const Key &key, const T &t ) : item(key, t) {}
        // exception-safe allocation, see C++ Standard 2003, clause 5.3.4p17
        void *operator new( size_t /*size*/, node_allocator_type &a ) {
            void *ptr = a.allocate(1);
            if(!ptr)
                tbb::internal::throw_exception(tbb::internal::eid_bad_alloc);
            return ptr;
        }
        // match placement-new form above to be called if exception thrown in constructor
        void operator delete( void *ptr, node_allocator_type &a ) { a.deallocate(static_cast<node*>(ptr),1); }
    };

    void delete_node( node_base *n ) {
        my_allocator.destroy( static_cast<node*>(n) );
        my_allocator.deallocate( static_cast<node*>(n), 1);
    }

    node *search_bucket( const key_type &key, bucket *b ) const {
        node *n = static_cast<node*>( b->node_list );
        while( is_valid(n) && !my_hash_compare.equal(key, n->item.first) )
            n = static_cast<node*>( n->next );
        __TBB_ASSERT(n != internal::rehash_req, "Search can be executed only for rehashed bucket");
        return n;
    }

    //! bucket accessor is to find, rehash, acquire a lock, and access a bucket
    class bucket_accessor : public bucket::scoped_t {
        bucket *my_b;
    public:
        bucket_accessor( concurrent_hash_map *base, const hashcode_t h, bool writer = false ) { acquire( base, h, writer ); }
        //! find a bucket by masked hashcode, optionally rehash, and acquire the lock
        inline void acquire( concurrent_hash_map *base, const hashcode_t h, bool writer = false ) {
            my_b = base->get_bucket( h );
            // TODO: actually, notification is unnecessary here, just hiding double-check
            if( itt_load_word_with_acquire(my_b->node_list) == internal::rehash_req
                && try_acquire( my_b->mutex, /*write=*/true ) )
            {
                if( my_b->node_list == internal::rehash_req ) base->rehash_bucket( my_b, h ); //recursive rehashing
            }
            else bucket::scoped_t::acquire( my_b->mutex, writer );
            __TBB_ASSERT( my_b->node_list != internal::rehash_req, NULL);
        }
        //! check whether bucket is locked for write
        bool is_writer() { return bucket::scoped_t::is_writer; }
        //! get bucket pointer
        bucket *operator() () { return my_b; }
    };

    // TODO refactor to hash_base
    void rehash_bucket( bucket *b_new, const hashcode_t h ) {
        __TBB_ASSERT( *(intptr_t*)(&b_new->mutex), "b_new must be locked (for write)");
        __TBB_ASSERT( h > 1, "The lowermost buckets can't be rehashed" );
        __TBB_store_with_release(b_new->node_list, internal::empty_rehashed); // mark rehashed
        hashcode_t mask = ( 1u<<__TBB_Log2( h ) ) - 1; // get parent mask from the topmost bit
#if __TBB_STATISTICS
        my_info_rehashes++; // invocations of rehash_bucket
#endif

        bucket_accessor b_old( this, h & mask );

        mask = (mask<<1) | 1; // get full mask for new bucket
        __TBB_ASSERT( (mask&(mask+1))==0 && (h & mask) == h, NULL );
    restart:
        for( node_base **p = &b_old()->node_list, *n = __TBB_load_with_acquire(*p); is_valid(n); n = *p ) {
            hashcode_t c = my_hash_compare.hash( static_cast<node*>(n)->item.first );
#if TBB_USE_ASSERT
            hashcode_t bmask = h & (mask>>1);
            bmask = bmask==0? 1 : ( 1u<<(__TBB_Log2( bmask )+1 ) ) - 1; // minimal mask of parent bucket
            __TBB_ASSERT( (c & bmask) == (h & bmask), "hash() function changed for key in table" );
#endif
            if( (c & mask) == h ) {
                if( !b_old.is_writer() )
                    if( !b_old.upgrade_to_writer() ) {
                        goto restart; // node ptr can be invalid due to concurrent erase
                    }
                *p = n->next; // exclude from b_old
                add_to_bucket( b_new, n );
            } else p = &n->next; // iterate to next item
        }
    }

public:

    class accessor;
    //! Combines data access, locking, and garbage collection.
    class const_accessor : private node::scoped_t /*which derived from no_copy*/ {
        friend class concurrent_hash_map<Key,T,HashCompare,Allocator>;
        friend class accessor;
    public:
        //! Type of value
        typedef const typename concurrent_hash_map::value_type value_type;

        //! True if result is empty.
        bool empty() const {return !my_node;}

        //! Set to null
        void release() {
            if( my_node ) {
                node::scoped_t::release();
                my_node = 0;
            }
        }

        //! Return reference to associated value in hash table.
        const_reference operator*() const {
            __TBB_ASSERT( my_node, "attempt to dereference empty accessor" );
            return my_node->item;
        }

        //! Return pointer to associated value in hash table.
        const_pointer operator->() const {
            return &operator*();
        }

        //! Create empty result
        const_accessor() : my_node(NULL) {}

        //! Destroy result after releasing the underlying reference.
        ~const_accessor() {
            my_node = NULL; // scoped lock's release() is called in its destructor
        }
    protected:
        bool is_writer() { return node::scoped_t::is_writer; }
        node *my_node;
        hashcode_t my_hash;
    };

    //! Allows write access to elements and combines data access, locking, and garbage collection.
    class accessor: public const_accessor {
    public:
        //! Type of value
        typedef typename concurrent_hash_map::value_type value_type;

        //! Return reference to associated value in hash table.
        reference operator*() const {
            __TBB_ASSERT( this->my_node, "attempt to dereference empty accessor" );
            return this->my_node->item;
        }

        //! Return pointer to associated value in hash table.
        pointer operator->() const {
            return &operator*();
        }
    };

    //! Construct empty table.
    concurrent_hash_map(const allocator_type &a = allocator_type())
        : internal::hash_map_base(), my_allocator(a)
    {}

    //! Construct empty table with n preallocated buckets. This number serves also as initial concurrency level.
    concurrent_hash_map(size_type n, const allocator_type &a = allocator_type())
        : my_allocator(a)
    {
        reserve( n );
    }

    //! Copy constructor
    concurrent_hash_map( const concurrent_hash_map& table, const allocator_type &a = allocator_type())
        : internal::hash_map_base(), my_allocator(a)
    {
        internal_copy(table);
    }

    //! Construction with copying iteration range and given allocator instance
    template<typename I>
    concurrent_hash_map(I first, I last, const allocator_type &a = allocator_type())
        : my_allocator(a)
    {
        reserve( std::distance(first, last) ); // TODO: load_factor?
        internal_copy(first, last);
    }

#if __TBB_INITIALIZER_LISTS_PRESENT
    //! Construct empty table with n preallocated buckets. This number serves also as initial concurrency level.
    concurrent_hash_map(const std::initializer_list<value_type> &il, const allocator_type &a = allocator_type())
        : my_allocator(a)
    {
        reserve(il.size());
        internal_copy(il.begin(), il.end());
    }

#endif //__TBB_INITIALIZER_LISTS_PRESENT

    //! Assignment
    concurrent_hash_map& operator=( const concurrent_hash_map& table ) {
        if( this!=&table ) {
            clear();
            internal_copy(table);
        }
        return *this;
    }

#if __TBB_INITIALIZER_LISTS_PRESENT
    //! Assignment
    concurrent_hash_map& operator=( const std::initializer_list<value_type> &il ) {
        clear();
        reserve(il.size());
        internal_copy(il.begin(), il.end());
        return *this;
    }
#endif //__TBB_INITIALIZER_LISTS_PRESENT


    //! Rehashes and optionally resizes the whole table.
    /** Useful to optimize performance before or after concurrent operations.
        Also enables using of find() and count() concurrent methods in serial context. */
    void rehash(size_type n = 0);

    //! Clear table
    void clear();

    //! Clear table and destroy it.
    ~concurrent_hash_map() { clear(); }

    //------------------------------------------------------------------------
    // Parallel algorithm support
    //------------------------------------------------------------------------
    range_type range( size_type grainsize=1 ) {
        return range_type( *this, grainsize );
    }
    const_range_type range( size_type grainsize=1 ) const {
        return const_range_type( *this, grainsize );
    }

    //------------------------------------------------------------------------
    // STL support - not thread-safe methods
    //------------------------------------------------------------------------
    iterator begin() {return iterator(*this,0,my_embedded_segment,my_embedded_segment->node_list);}
    iterator end() {return iterator(*this,0,0,0);}
    const_iterator begin() const {return const_iterator(*this,0,my_embedded_segment,my_embedded_segment->node_list);}
    const_iterator end() const {return const_iterator(*this,0,0,0);}
    std::pair<iterator, iterator> equal_range( const Key& key ) { return internal_equal_range(key, end()); }
    std::pair<const_iterator, const_iterator> equal_range( const Key& key ) const { return internal_equal_range(key, end()); }

    //! Number of items in table.
    size_type size() const { return my_size; }

    //! True if size()==0.
    bool empty() const { return my_size == 0; }

    //! Upper bound on size.
    size_type max_size() const {return (~size_type(0))/sizeof(node);}

    //! Returns the current number of buckets
    size_type bucket_count() const { return my_mask+1; }

    //! return allocator object
    allocator_type get_allocator() const { return this->my_allocator; }

    //! swap two instances. Iterators are invalidated
    void swap(concurrent_hash_map &table);

    //------------------------------------------------------------------------
    // concurrent map operations
    //------------------------------------------------------------------------

    //! Return count of items (0 or 1)
    size_type count( const Key &key ) const {
        return const_cast<concurrent_hash_map*>(this)->lookup(/*insert*/false, key, NULL, NULL, /*write=*/false );
    }

    //! Find item and acquire a read lock on the item.
    /** Return true if item is found, false otherwise. */
    bool find( const_accessor &result, const Key &key ) const {
        result.release();
        return const_cast<concurrent_hash_map*>(this)->lookup(/*insert*/false, key, NULL, &result, /*write=*/false );
    }

    //! Find item and acquire a write lock on the item.
    /** Return true if item is found, false otherwise. */
    bool find( accessor &result, const Key &key ) {
        result.release();
        return lookup(/*insert*/false, key, NULL, &result, /*write=*/true );
    }

    //! Insert item (if not already present) and acquire a read lock on the item.
    /** Returns true if item is new. */
    bool insert( const_accessor &result, const Key &key ) {
        result.release();
        return lookup(/*insert*/true, key, NULL, &result, /*write=*/false );
    }

    //! Insert item (if not already present) and acquire a write lock on the item.
    /** Returns true if item is new. */
    bool insert( accessor &result, const Key &key ) {
        result.release();
        return lookup(/*insert*/true, key, NULL, &result, /*write=*/true );
    }

    //! Insert item by copying if there is no such key present already and acquire a read lock on the item.
    /** Returns true if item is new. */
    bool insert( const_accessor &result, const value_type &value ) {
        result.release();
        return lookup(/*insert*/true, value.first, &value.second, &result, /*write=*/false );
    }

    //! Insert item by copying if there is no such key present already and acquire a write lock on the item.
    /** Returns true if item is new. */
    bool insert( accessor &result, const value_type &value ) {
        result.release();
        return lookup(/*insert*/true, value.first, &value.second, &result, /*write=*/true );
    }

    //! Insert item by copying if there is no such key present already
    /** Returns true if item is inserted. */
    bool insert( const value_type &value ) {
        return lookup(/*insert*/true, value.first, &value.second, NULL, /*write=*/false );
    }

    //! Insert range [first, last)
    template<typename I>
    void insert(I first, I last) {
        for(; first != last; ++first)
            insert( *first );
    }

    //! Erase item.
    /** Return true if item was erased by particularly this call. */
    bool erase( const Key& key );

    //! Erase item by const_accessor.
    /** Return true if item was erased by particularly this call. */
    bool erase( const_accessor& item_accessor ) {
        return exclude( item_accessor );
    }

    //! Erase item by accessor.
    /** Return true if item was erased by particularly this call. */
    bool erase( accessor& item_accessor ) {
        return exclude( item_accessor );
    }

protected:
    //! Insert or find item and optionally acquire a lock on the item.
    bool lookup( bool op_insert, const Key &key, const T *t, const_accessor *result, bool write );

    //! delete item by accessor
    bool exclude( const_accessor &item_accessor );

    //! Returns an iterator for an item defined by the key, or for the next item after it (if upper==true)
    template<typename I>
    std::pair<I, I> internal_equal_range( const Key& key, I end ) const;

    //! Copy "source" to *this, where *this must start out empty.
    void internal_copy( const concurrent_hash_map& source );

    template<typename I>
    void internal_copy(I first, I last);

    //! Fast find when no concurrent erasure is used. For internal use inside TBB only!
    /** Return pointer to item with given key, or NULL if no such item exists.
        Must not be called concurrently with erasure operations. */
    const_pointer internal_fast_find( const Key& key ) const {
        hashcode_t h = my_hash_compare.hash( key );
        hashcode_t m = (hashcode_t) itt_load_word_with_acquire( my_mask );
        node *n;
    restart:
        __TBB_ASSERT((m&(m+1))==0, NULL);
        bucket *b = get_bucket( h & m );
        // TODO: actually, notification is unnecessary here, just hiding double-check
        if( itt_load_word_with_acquire(b->node_list) == internal::rehash_req )
        {
            bucket::scoped_t lock;
            if( lock.try_acquire( b->mutex, /*write=*/true ) ) {
                if( b->node_list == internal::rehash_req)
                    const_cast<concurrent_hash_map*>(this)->rehash_bucket( b, h & m ); //recursive rehashing
            }
            else lock.acquire( b->mutex, /*write=*/false );
            __TBB_ASSERT(b->node_list!=internal::rehash_req,NULL);
        }
        n = search_bucket( key, b );
        if( n )
            return &n->item;
        else if( check_mask_race( h, m ) )
            goto restart;
        return 0;
    }
};

#if _MSC_VER && !defined(__INTEL_COMPILER)
    // Suppress "conditional expression is constant" warning.
    #pragma warning( push )
    #pragma warning( disable: 4127 )
#endif

template<typename Key, typename T, typename HashCompare, typename A>
bool concurrent_hash_map<Key,T,HashCompare,A>::lookup( bool op_insert, const Key &key, const T *t, const_accessor *result, bool write ) {
    __TBB_ASSERT( !result || !result->my_node, NULL );
    bool return_value;
    hashcode_t const h = my_hash_compare.hash( key );
    hashcode_t m = (hashcode_t) itt_load_word_with_acquire( my_mask );
    segment_index_t grow_segment = 0;
    node *n, *tmp_n = 0;
    restart:
    {//lock scope
        __TBB_ASSERT((m&(m+1))==0, NULL);
        return_value = false;
        // get bucket
        bucket_accessor b( this, h & m );

        // find a node
        n = search_bucket( key, b() );
        if( op_insert ) {
            // [opt] insert a key
            if( !n ) {
                if( !tmp_n ) {
                    if(t) tmp_n = new( my_allocator ) node(key, *t);
                    else  tmp_n = new( my_allocator ) node(key);
                }
                if( !b.is_writer() && !b.upgrade_to_writer() ) { // TODO: improved insertion
                    // Rerun search_list, in case another thread inserted the item during the upgrade.
                    n = search_bucket( key, b() );
                    if( is_valid(n) ) { // unfortunately, it did
                        b.downgrade_to_reader();
                        goto exists;
                    }
                }
                if( check_mask_race(h, m) )
                    goto restart; // b.release() is done in ~b().
                // insert and set flag to grow the container
                grow_segment = insert_new_node( b(), n = tmp_n, m );
                tmp_n = 0;
                return_value = true;
            }
        } else { // find or count
            if( !n ) {
                if( check_mask_race( h, m ) )
                    goto restart; // b.release() is done in ~b(). TODO: replace by continue
                return false;
            }
            return_value = true;
        }
    exists:
        if( !result ) goto check_growth;
        // TODO: the following seems as generic/regular operation
        // acquire the item
        if( !result->try_acquire( n->mutex, write ) ) {
            for( tbb::internal::atomic_backoff backoff(true);; ) {
                if( result->try_acquire( n->mutex, write ) ) break;
                if( !backoff.bounded_pause() ) {
                    // the wait takes really long, restart the operation
                    b.release();
                    __TBB_ASSERT( !op_insert || !return_value, "Can't acquire new item in locked bucket?" );
                    __TBB_Yield();
                    m = (hashcode_t) itt_load_word_with_acquire( my_mask );
                    goto restart;
                }
            }
        }
    }//lock scope
    result->my_node = n;
    result->my_hash = h;
check_growth:
    // [opt] grow the container
    if( grow_segment ) {
#if __TBB_STATISTICS
        my_info_resizes++; // concurrent ones
#endif
        enable_segment( grow_segment );
    }
    if( tmp_n ) // if op_insert only
        delete_node( tmp_n );
    return return_value;
}

template<typename Key, typename T, typename HashCompare, typename A>
template<typename I>
std::pair<I, I> concurrent_hash_map<Key,T,HashCompare,A>::internal_equal_range( const Key& key, I end_ ) const {
    hashcode_t h = my_hash_compare.hash( key );
    hashcode_t m = my_mask;
    __TBB_ASSERT((m&(m+1))==0, NULL);
    h &= m;
    bucket *b = get_bucket( h );
    while( b->node_list == internal::rehash_req ) {
        m = ( 1u<<__TBB_Log2( h ) ) - 1; // get parent mask from the topmost bit
        b = get_bucket( h &= m );
    }
    node *n = search_bucket( key, b );
    if( !n )
        return std::make_pair(end_, end_);
    iterator lower(*this, h, b, n), upper(lower);
    return std::make_pair(lower, ++upper);
}

template<typename Key, typename T, typename HashCompare, typename A>
bool concurrent_hash_map<Key,T,HashCompare,A>::exclude( const_accessor &item_accessor ) {
    __TBB_ASSERT( item_accessor.my_node, NULL );
    node_base *const n = item_accessor.my_node;
    hashcode_t const h = item_accessor.my_hash;
    hashcode_t m = (hashcode_t) itt_load_word_with_acquire( my_mask );
    do {
        // get bucket
        bucket_accessor b( this, h & m, /*writer=*/true );
        node_base **p = &b()->node_list;
        while( *p && *p != n )
            p = &(*p)->next;
        if( !*p ) { // someone else was first
            if( check_mask_race( h, m ) )
                continue;
            item_accessor.release();
            return false;
        }
        __TBB_ASSERT( *p == n, NULL );
        *p = n->next; // remove from container
        my_size--;
        break;
    } while(true);
    if( !item_accessor.is_writer() ) // need to get exclusive lock
        item_accessor.upgrade_to_writer(); // return value means nothing here
    item_accessor.release();
    delete_node( n ); // Only one thread can delete it
    return true;
}

template<typename Key, typename T, typename HashCompare, typename A>
bool concurrent_hash_map<Key,T,HashCompare,A>::erase( const Key &key ) {
    node_base *n;
    hashcode_t const h = my_hash_compare.hash( key );
    hashcode_t m = (hashcode_t) itt_load_word_with_acquire( my_mask );
restart:
    {//lock scope
        // get bucket
        bucket_accessor b( this, h & m );
    search:
        node_base **p = &b()->node_list;
        n = *p;
        while( is_valid(n) && !my_hash_compare.equal(key, static_cast<node*>(n)->item.first ) ) {
            p = &n->next;
            n = *p;
        }
        if( !n ) { // not found, but mask could be changed
            if( check_mask_race( h, m ) )
                goto restart;
            return false;
        }
        else if( !b.is_writer() && !b.upgrade_to_writer() ) {
            if( check_mask_race( h, m ) ) // contended upgrade, check mask
                goto restart;
            goto search;
        }
        *p = n->next;
        my_size--;
    }
    {
        typename node::scoped_t item_locker( n->mutex, /*write=*/true );
    }
    // note: there should be no threads pretending to acquire this mutex again, do not try to upgrade const_accessor!
    delete_node( n ); // Only one thread can delete it due to write lock on the bucket
    return true;
}

template<typename Key, typename T, typename HashCompare, typename A>
void concurrent_hash_map<Key,T,HashCompare,A>::swap(concurrent_hash_map<Key,T,HashCompare,A> &table) {
    std::swap(this->my_allocator, table.my_allocator);
    std::swap(this->my_hash_compare, table.my_hash_compare);
    internal_swap(table);
}

template<typename Key, typename T, typename HashCompare, typename A>
void concurrent_hash_map<Key,T,HashCompare,A>::rehash(size_type sz) {
    reserve( sz ); // TODO: add reduction of number of buckets as well
    hashcode_t mask = my_mask;
    hashcode_t b = (mask+1)>>1; // size or first index of the last segment
    __TBB_ASSERT((b&(b-1))==0, NULL); // zero or power of 2
    bucket *bp = get_bucket( b ); // only the last segment should be scanned for rehashing
    for(; b <= mask; b++, bp++ ) {
        node_base *n = bp->node_list;
        __TBB_ASSERT( is_valid(n) || n == internal::empty_rehashed || n == internal::rehash_req, "Broken internal structure" );
        __TBB_ASSERT( *reinterpret_cast<intptr_t*>(&bp->mutex) == 0, "concurrent or unexpectedly terminated operation during rehash() execution" );
        if( n == internal::rehash_req ) { // rehash bucket, conditional because rehashing of a previous bucket may affect this one
            hashcode_t h = b; bucket *b_old = bp;
            do {
                __TBB_ASSERT( h > 1, "The lowermost buckets can't be rehashed" );
                hashcode_t m = ( 1u<<__TBB_Log2( h ) ) - 1; // get parent mask from the topmost bit
                b_old = get_bucket( h &= m );
            } while( b_old->node_list == internal::rehash_req );
            // now h - is index of the root rehashed bucket b_old
            mark_rehashed_levels( h ); // mark all non-rehashed children recursively across all segments
            for( node_base **p = &b_old->node_list, *q = *p; is_valid(q); q = *p ) {
                hashcode_t c = my_hash_compare.hash( static_cast<node*>(q)->item.first );
                if( (c & mask) != h ) { // should be rehashed
                    *p = q->next; // exclude from b_old
                    bucket *b_new = get_bucket( c & mask );
                    __TBB_ASSERT( b_new->node_list != internal::rehash_req, "hash() function changed for key in table or internal error" );
                    add_to_bucket( b_new, q );
                } else p = &q->next; // iterate to next item
            }
        }
    }
#if TBB_USE_PERFORMANCE_WARNINGS
    int current_size = int(my_size), buckets = int(mask)+1, empty_buckets = 0, overpopulated_buckets = 0; // usage statistics
    static bool reported = false;
#endif
#if TBB_USE_ASSERT || TBB_USE_PERFORMANCE_WARNINGS
    for( b = 0; b <= mask; b++ ) {// only last segment should be scanned for rehashing
        if( b & (b-2) ) ++bp; // not the beginning of a segment
        else bp = get_bucket( b );
        node_base *n = bp->node_list;
        __TBB_ASSERT( *reinterpret_cast<intptr_t*>(&bp->mutex) == 0, "concurrent or unexpectedly terminated operation during rehash() execution" );
        __TBB_ASSERT( is_valid(n) || n == internal::empty_rehashed, "Broken internal structure" );
#if TBB_USE_PERFORMANCE_WARNINGS
        if( n == internal::empty_rehashed ) empty_buckets++;
        else if( n->next ) overpopulated_buckets++;
#endif
#if TBB_USE_ASSERT
        for( ; is_valid(n); n = n->next ) {
            hashcode_t h = my_hash_compare.hash( static_cast<node*>(n)->item.first ) & mask;
            __TBB_ASSERT( h == b, "hash() function changed for key in table or internal error" );
        }
#endif
    }
#endif // TBB_USE_ASSERT || TBB_USE_PERFORMANCE_WARNINGS
#if TBB_USE_PERFORMANCE_WARNINGS
    if( buckets > current_size) empty_buckets -= buckets - current_size;
    else overpopulated_buckets -= current_size - buckets; // TODO: load_factor?
    if( !reported && buckets >= 512 && ( 2*empty_buckets > current_size || 2*overpopulated_buckets > current_size ) ) {
        tbb::internal::runtime_warning(
            "Performance is not optimal because the hash function produces bad randomness in lower bits in %s.\nSize: %d  Empties: %d  Overlaps: %d",
            typeid(*this).name(), current_size, empty_buckets, overpopulated_buckets );
        reported = true;
    }
#endif
}

template<typename Key, typename T, typename HashCompare, typename A>
void concurrent_hash_map<Key,T,HashCompare,A>::clear() {
    hashcode_t m = my_mask;
    __TBB_ASSERT((m&(m+1))==0, NULL);
#if TBB_USE_ASSERT || TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
#if TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
    int current_size = int(my_size), buckets = int(m)+1, empty_buckets = 0, overpopulated_buckets = 0; // usage statistics
    static bool reported = false;
#endif
    bucket *bp = 0;
    // check consistency
    for( segment_index_t b = 0; b <= m; b++ ) {
        if( b & (b-2) ) ++bp; // not the beginning of a segment
        else bp = get_bucket( b );
        node_base *n = bp->node_list;
        __TBB_ASSERT( is_valid(n) || n == internal::empty_rehashed || n == internal::rehash_req, "Broken internal structure" );
        __TBB_ASSERT( *reinterpret_cast<intptr_t*>(&bp->mutex) == 0, "concurrent or unexpectedly terminated operation during clear() execution" );
#if TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
        if( n == internal::empty_rehashed ) empty_buckets++;
        else if( n == internal::rehash_req ) buckets--;
        else if( n->next ) overpopulated_buckets++;
#endif
#if __TBB_EXTRA_DEBUG
        for(; is_valid(n); n = n->next ) {
            hashcode_t h = my_hash_compare.hash( static_cast<node*>(n)->item.first );
            h &= m;
            __TBB_ASSERT( h == b || get_bucket(h)->node_list == internal::rehash_req, "hash() function changed for key in table or internal error" );
        }
#endif
    }
#if TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
#if __TBB_STATISTICS
    printf( "items=%d buckets: capacity=%d rehashed=%d empty=%d overpopulated=%d"
        " concurrent: resizes=%u rehashes=%u restarts=%u\n",
        current_size, int(m+1), buckets, empty_buckets, overpopulated_buckets,
        unsigned(my_info_resizes), unsigned(my_info_rehashes), unsigned(my_info_restarts) );
    my_info_resizes = 0; // concurrent ones
    my_info_restarts = 0; // race collisions
    my_info_rehashes = 0;  // invocations of rehash_bucket
#endif
    if( buckets > current_size) empty_buckets -= buckets - current_size;
    else overpopulated_buckets -= current_size - buckets; // TODO: load_factor?
    if( !reported && buckets >= 512 && ( 2*empty_buckets > current_size || 2*overpopulated_buckets > current_size ) ) {
        tbb::internal::runtime_warning(
            "Performance is not optimal because the hash function produces bad randomness in lower bits in %s.\nSize: %d  Empties: %d  Overlaps: %d",
            typeid(*this).name(), current_size, empty_buckets, overpopulated_buckets );
        reported = true;
    }
#endif
#endif//TBB_USE_ASSERT || TBB_USE_PERFORMANCE_WARNINGS || __TBB_STATISTICS
    my_size = 0;
    segment_index_t s = segment_index_of( m );
    __TBB_ASSERT( s+1 == pointers_per_table || !my_table[s+1], "wrong mask or concurrent grow" );
    cache_aligned_allocator<bucket> alloc;
    do {
        __TBB_ASSERT( is_valid( my_table[s] ), "wrong mask or concurrent grow" );
        segment_ptr_t buckets_ptr = my_table[s];
        size_type sz = segment_size( s ? s : 1 );
        for( segment_index_t i = 0; i < sz; i++ )
            for( node_base *n = buckets_ptr[i].node_list; is_valid(n); n = buckets_ptr[i].node_list ) {
                buckets_ptr[i].node_list = n->next;
                delete_node( n );
            }
        if( s >= first_block) // the first segment or the next
            alloc.deallocate( buckets_ptr, sz );
        else if( s == embedded_block && embedded_block != first_block )
            alloc.deallocate( buckets_ptr, segment_size(first_block)-embedded_buckets );
        if( s >= embedded_block ) my_table[s] = 0;
    } while(s-- > 0);
    my_mask = embedded_buckets - 1;
}

template<typename Key, typename T, typename HashCompare, typename A>
void concurrent_hash_map<Key,T,HashCompare,A>::internal_copy( const concurrent_hash_map& source ) {
    reserve( source.my_size ); // TODO: load_factor?
    hashcode_t mask = source.my_mask;
    if( my_mask == mask ) { // optimized version
        bucket *dst = 0, *src = 0;
        bool rehash_required = false;
        for( hashcode_t k = 0; k <= mask; k++ ) {
            if( k & (k-2) ) ++dst,src++; // not the beginning of a segment
            else { dst = get_bucket( k ); src = source.get_bucket( k ); }
            __TBB_ASSERT( dst->node_list != internal::rehash_req, "Invalid bucket in destination table");
            node *n = static_cast<node*>( src->node_list );
            if( n == internal::rehash_req ) { // source is not rehashed, items are in previous buckets
                rehash_required = true;
                dst->node_list = internal::rehash_req;
            } else for(; n; n = static_cast<node*>( n->next ) ) {
                add_to_bucket( dst, new( my_allocator ) node(n->item.first, n->item.second) );
                ++my_size; // TODO: replace by non-atomic op
            }
        }
        if( rehash_required ) rehash();
    } else internal_copy( source.begin(), source.end() );
}

template<typename Key, typename T, typename HashCompare, typename A>
template<typename I>
void concurrent_hash_map<Key,T,HashCompare,A>::internal_copy(I first, I last) {
    hashcode_t m = my_mask;
    for(; first != last; ++first) {
        hashcode_t h = my_hash_compare.hash( first->first );
        bucket *b = get_bucket( h & m );
        __TBB_ASSERT( b->node_list != internal::rehash_req, "Invalid bucket in destination table");
        node *n = new( my_allocator ) node(first->first, first->second);
        add_to_bucket( b, n );
        ++my_size; // TODO: replace by non-atomic op
    }
}

} // namespace interface5

using interface5::concurrent_hash_map;


template<typename Key, typename T, typename HashCompare, typename A1, typename A2>
inline bool operator==(const concurrent_hash_map<Key, T, HashCompare, A1> &a, const concurrent_hash_map<Key, T, HashCompare, A2> &b) {
    if(a.size() != b.size()) return false;
    typename concurrent_hash_map<Key, T, HashCompare, A1>::const_iterator i(a.begin()), i_end(a.end());
    typename concurrent_hash_map<Key, T, HashCompare, A2>::const_iterator j, j_end(b.end());
    for(; i != i_end; ++i) {
        j = b.equal_range(i->first).first;
        if( j == j_end || !(i->second == j->second) ) return false;
    }
    return true;
}

template<typename Key, typename T, typename HashCompare, typename A1, typename A2>
inline bool operator!=(const concurrent_hash_map<Key, T, HashCompare, A1> &a, const concurrent_hash_map<Key, T, HashCompare, A2> &b)
{    return !(a == b); }

template<typename Key, typename T, typename HashCompare, typename A>
inline void swap(concurrent_hash_map<Key, T, HashCompare, A> &a, concurrent_hash_map<Key, T, HashCompare, A> &b)
{    a.swap( b ); }

#if _MSC_VER && !defined(__INTEL_COMPILER)
    #pragma warning( pop )
#endif // warning 4127 is back

} // namespace tbb

#endif /* __TBB_concurrent_hash_map_H */