aboutsummaryrefslogtreecommitdiff
path: root/src/db.cpp
blob: 5ca9ea2c34f6a07c053450d1589bf66cfe10aae3 (plain)
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
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "db.h"
#include "util.h"
#include "main.h"
#include <boost/version.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>

#ifndef WIN32
#include "sys/stat.h"
#endif

using namespace std;
using namespace boost;


unsigned int nWalletDBUpdated;



//
// CDB
//

CDBEnv bitdb;

void CDBEnv::EnvShutdown()
{
    if (!fDbEnvInit)
        return;

    fDbEnvInit = false;
    int ret = dbenv.close(0);
    if (ret != 0)
        printf("EnvShutdown exception: %s (%d)\n", DbEnv::strerror(ret), ret);
    if (!fMockDb)
        DbEnv(0).remove(GetDataDir().string().c_str(), 0);
}

CDBEnv::CDBEnv() : dbenv(DB_CXX_NO_EXCEPTIONS)
{
}

CDBEnv::~CDBEnv()
{
    EnvShutdown();
}

void CDBEnv::Close()
{
    EnvShutdown();
}

bool CDBEnv::Open(boost::filesystem::path pathEnv_)
{
    if (fDbEnvInit)
        return true;

    if (fShutdown)
        return false;

    pathEnv = pathEnv_;
    filesystem::path pathDataDir = pathEnv;
    filesystem::path pathLogDir = pathDataDir / "database";
    filesystem::create_directory(pathLogDir);
    filesystem::path pathErrorFile = pathDataDir / "db.log";
    printf("dbenv.open LogDir=%s ErrorFile=%s\n", pathLogDir.string().c_str(), pathErrorFile.string().c_str());

    unsigned int nEnvFlags = 0;
    if (GetBoolArg("-privdb", true))
        nEnvFlags |= DB_PRIVATE;

    int nDbCache = GetArg("-dbcache", 25);
    dbenv.set_lg_dir(pathLogDir.string().c_str());
    dbenv.set_cachesize(nDbCache / 1024, (nDbCache % 1024)*1048576, 1);
    dbenv.set_lg_bsize(1048576);
    dbenv.set_lg_max(10485760);
    dbenv.set_lk_max_locks(40000);
    dbenv.set_lk_max_objects(40000);
    dbenv.set_errfile(fopen(pathErrorFile.string().c_str(), "a")); /// debug
    dbenv.set_flags(DB_AUTO_COMMIT, 1);
    dbenv.set_flags(DB_TXN_WRITE_NOSYNC, 1);
    dbenv.log_set_config(DB_LOG_AUTO_REMOVE, 1);
    int ret = dbenv.open(pathDataDir.string().c_str(),
                     DB_CREATE     |
                     DB_INIT_LOCK  |
                     DB_INIT_LOG   |
                     DB_INIT_MPOOL |
                     DB_INIT_TXN   |
                     DB_THREAD     |
                     DB_RECOVER    |
                     nEnvFlags,
                     S_IRUSR | S_IWUSR);
    if (ret != 0)
        return error("CDB() : error %s (%d) opening database environment", DbEnv::strerror(ret), ret);

    fDbEnvInit = true;
    fMockDb = false;
    return true;
}

void CDBEnv::MakeMock()
{
    if (fDbEnvInit)
        throw runtime_error("CDBEnv::MakeMock(): already initialized");

    if (fShutdown)
        throw runtime_error("CDBEnv::MakeMock(): during shutdown");

    printf("CDBEnv::MakeMock()\n");

    dbenv.set_cachesize(1, 0, 1);
    dbenv.set_lg_bsize(10485760*4);
    dbenv.set_lg_max(10485760);
    dbenv.set_lk_max_locks(10000);
    dbenv.set_lk_max_objects(10000);
    dbenv.set_flags(DB_AUTO_COMMIT, 1);
    dbenv.log_set_config(DB_LOG_IN_MEMORY, 1);
    int ret = dbenv.open(NULL,
                     DB_CREATE     |
                     DB_INIT_LOCK  |
                     DB_INIT_LOG   |
                     DB_INIT_MPOOL |
                     DB_INIT_TXN   |
                     DB_THREAD     |
                     DB_PRIVATE,
                     S_IRUSR | S_IWUSR);
    if (ret > 0)
        throw runtime_error(strprintf("CDBEnv::MakeMock(): error %d opening database environment", ret));

    fDbEnvInit = true;
    fMockDb = true;
}

CDBEnv::VerifyResult CDBEnv::Verify(std::string strFile, bool (*recoverFunc)(CDBEnv& dbenv, std::string strFile))
{
    LOCK(cs_db);
    assert(mapFileUseCount.count(strFile) == 0);

    Db db(&dbenv, 0);
    int result = db.verify(strFile.c_str(), NULL, NULL, 0);
    if (result == 0)
        return VERIFY_OK;
    else if (recoverFunc == NULL)
        return RECOVER_FAIL;

    // Try to recover:
    bool fRecovered = (*recoverFunc)(*this, strFile);
    return (fRecovered ? RECOVER_OK : RECOVER_FAIL);
}

bool CDBEnv::Salvage(std::string strFile, bool fAggressive,
                     std::vector<CDBEnv::KeyValPair >& vResult)
{
    LOCK(cs_db);
    assert(mapFileUseCount.count(strFile) == 0);

    u_int32_t flags = DB_SALVAGE;
    if (fAggressive) flags |= DB_AGGRESSIVE;

    stringstream strDump;

    Db db(&dbenv, 0);
    int result = db.verify(strFile.c_str(), NULL, &strDump, flags);
    if (result != 0)
    {
        printf("ERROR: db salvage failed\n");
        return false;
    }

    // Format of bdb dump is ascii lines:
    // header lines...
    // HEADER=END
    // hexadecimal key
    // hexadecimal value
    // ... repeated
    // DATA=END

    string strLine;
    while (!strDump.eof() && strLine != "HEADER=END")
        getline(strDump, strLine); // Skip past header

    std::string keyHex, valueHex;
    while (!strDump.eof() && keyHex != "DATA=END")
    {
        getline(strDump, keyHex);
        if (keyHex != "DATA_END")
        {
            getline(strDump, valueHex);
            vResult.push_back(make_pair(ParseHex(keyHex),ParseHex(valueHex)));
        }
    }

    return (result == 0);
}


void CDBEnv::CheckpointLSN(std::string strFile)
{
    dbenv.txn_checkpoint(0, 0, 0);
    if (fMockDb)
        return;
    dbenv.lsn_reset(strFile.c_str(), 0);
}


CDB::CDB(const char *pszFile, const char* pszMode) :
    pdb(NULL), activeTxn(NULL)
{
    int ret;
    if (pszFile == NULL)
        return;

    fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
    bool fCreate = strchr(pszMode, 'c');
    unsigned int nFlags = DB_THREAD;
    if (fCreate)
        nFlags |= DB_CREATE;

    {
        LOCK(bitdb.cs_db);
        if (!bitdb.Open(GetDataDir()))
            throw runtime_error("env open failed");

        strFile = pszFile;
        ++bitdb.mapFileUseCount[strFile];
        pdb = bitdb.mapDb[strFile];
        if (pdb == NULL)
        {
            pdb = new Db(&bitdb.dbenv, 0);

            bool fMockDb = bitdb.IsMock();
            if (fMockDb)
            {
                DbMpoolFile*mpf = pdb->get_mpf();
                ret = mpf->set_flags(DB_MPOOL_NOFILE, 1);
                if (ret != 0)
                    throw runtime_error(strprintf("CDB() : failed to configure for no temp file backing for database %s", pszFile));
            }

            ret = pdb->open(NULL,      // Txn pointer
                            fMockDb ? NULL : pszFile,   // Filename
                            fMockDb ? pszFile : "main", // Logical db name
                            DB_BTREE,  // Database type
                            nFlags,    // Flags
                            0);

            if (ret != 0)
            {
                delete pdb;
                pdb = NULL;
                --bitdb.mapFileUseCount[strFile];
                strFile = "";
                throw runtime_error(strprintf("CDB() : can't open database file %s, error %d", pszFile, ret));
            }

            if (fCreate && !Exists(string("version")))
            {
                bool fTmp = fReadOnly;
                fReadOnly = false;
                WriteVersion(CLIENT_VERSION);
                fReadOnly = fTmp;
            }

            bitdb.mapDb[strFile] = pdb;
        }
    }
}

static bool IsChainFile(std::string strFile)
{
    if (strFile == "coins.dat" || strFile == "chain.dat")
        return true;

    return false;
}

void CDB::Flush()
{
    if (activeTxn)
        return;

    // Flush database activity from memory pool to disk log
    unsigned int nMinutes = 0;
    if (fReadOnly)
        nMinutes = 1;
    if (IsChainFile(strFile))
        nMinutes = 2;
    if (IsChainFile(strFile) && IsInitialBlockDownload())
        nMinutes = 5;

    bitdb.dbenv.txn_checkpoint(nMinutes ? GetArg("-dblogsize", 100)*1024 : 0, nMinutes, 0);
}

void CDB::Close()
{
    if (!pdb)
        return;
    if (activeTxn)
        activeTxn->abort();
    activeTxn = NULL;
    pdb = NULL;

    Flush();

    {
        LOCK(bitdb.cs_db);
        --bitdb.mapFileUseCount[strFile];
    }
}

void CDBEnv::CloseDb(const string& strFile)
{
    {
        LOCK(cs_db);
        if (mapDb[strFile] != NULL)
        {
            // Close the database handle
            Db* pdb = mapDb[strFile];
            pdb->close(0);
            delete pdb;
            mapDb[strFile] = NULL;
        }
    }
}

bool CDBEnv::RemoveDb(const string& strFile)
{
    this->CloseDb(strFile);

    LOCK(cs_db);
    int rc = dbenv.dbremove(NULL, strFile.c_str(), NULL, DB_AUTO_COMMIT);
    return (rc == 0);
}

bool CDB::Rewrite(const string& strFile, const char* pszSkip)
{
    while (!fShutdown)
    {
        {
            LOCK(bitdb.cs_db);
            if (!bitdb.mapFileUseCount.count(strFile) || bitdb.mapFileUseCount[strFile] == 0)
            {
                // Flush log data to the dat file
                bitdb.CloseDb(strFile);
                bitdb.CheckpointLSN(strFile);
                bitdb.mapFileUseCount.erase(strFile);

                bool fSuccess = true;
                printf("Rewriting %s...\n", strFile.c_str());
                string strFileRes = strFile + ".rewrite";
                { // surround usage of db with extra {}
                    CDB db(strFile.c_str(), "r");
                    Db* pdbCopy = new Db(&bitdb.dbenv, 0);

                    int ret = pdbCopy->open(NULL,                 // Txn pointer
                                            strFileRes.c_str(),   // Filename
                                            "main",    // Logical db name
                                            DB_BTREE,  // Database type
                                            DB_CREATE,    // Flags
                                            0);
                    if (ret > 0)
                    {
                        printf("Cannot create database file %s\n", strFileRes.c_str());
                        fSuccess = false;
                    }

                    Dbc* pcursor = db.GetCursor();
                    if (pcursor)
                        while (fSuccess)
                        {
                            CDataStream ssKey(SER_DISK, CLIENT_VERSION);
                            CDataStream ssValue(SER_DISK, CLIENT_VERSION);
                            int ret = db.ReadAtCursor(pcursor, ssKey, ssValue, DB_NEXT);
                            if (ret == DB_NOTFOUND)
                            {
                                pcursor->close();
                                break;
                            }
                            else if (ret != 0)
                            {
                                pcursor->close();
                                fSuccess = false;
                                break;
                            }
                            if (pszSkip &&
                                strncmp(&ssKey[0], pszSkip, std::min(ssKey.size(), strlen(pszSkip))) == 0)
                                continue;
                            if (strncmp(&ssKey[0], "\x07version", 8) == 0)
                            {
                                // Update version:
                                ssValue.clear();
                                ssValue << CLIENT_VERSION;
                            }
                            Dbt datKey(&ssKey[0], ssKey.size());
                            Dbt datValue(&ssValue[0], ssValue.size());
                            int ret2 = pdbCopy->put(NULL, &datKey, &datValue, DB_NOOVERWRITE);
                            if (ret2 > 0)
                                fSuccess = false;
                        }
                    if (fSuccess)
                    {
                        db.Close();
                        bitdb.CloseDb(strFile);
                        if (pdbCopy->close(0))
                            fSuccess = false;
                        delete pdbCopy;
                    }
                }
                if (fSuccess)
                {
                    Db dbA(&bitdb.dbenv, 0);
                    if (dbA.remove(strFile.c_str(), NULL, 0))
                        fSuccess = false;
                    Db dbB(&bitdb.dbenv, 0);
                    if (dbB.rename(strFileRes.c_str(), NULL, strFile.c_str(), 0))
                        fSuccess = false;
                }
                if (!fSuccess)
                    printf("Rewriting of %s FAILED!\n", strFileRes.c_str());
                return fSuccess;
            }
        }
        Sleep(100);
    }
    return false;
}


void CDBEnv::Flush(bool fShutdown)
{
    int64 nStart = GetTimeMillis();
    // Flush log data to the actual data file
    //  on all files that are not in use
    printf("Flush(%s)%s\n", fShutdown ? "true" : "false", fDbEnvInit ? "" : " db not started");
    if (!fDbEnvInit)
        return;
    {
        LOCK(cs_db);
        map<string, int>::iterator mi = mapFileUseCount.begin();
        while (mi != mapFileUseCount.end())
        {
            string strFile = (*mi).first;
            int nRefCount = (*mi).second;
            printf("%s refcount=%d\n", strFile.c_str(), nRefCount);
            if (nRefCount == 0)
            {
                // Move log data to the dat file
                CloseDb(strFile);
                printf("%s checkpoint\n", strFile.c_str());
                dbenv.txn_checkpoint(0, 0, 0);
                if (!IsChainFile(strFile) || fDetachDB) {
                    printf("%s detach\n", strFile.c_str());
                    if (!fMockDb)
                        dbenv.lsn_reset(strFile.c_str(), 0);
                }
                printf("%s closed\n", strFile.c_str());
                mapFileUseCount.erase(mi++);
            }
            else
                mi++;
        }
        printf("DBFlush(%s)%s ended %15"PRI64d"ms\n", fShutdown ? "true" : "false", fDbEnvInit ? "" : " db not started", GetTimeMillis() - nStart);
        if (fShutdown)
        {
            char** listp;
            if (mapFileUseCount.empty())
            {
                dbenv.log_archive(&listp, DB_ARCH_REMOVE);
                Close();
            }
        }
    }
}






//
// CChainDB and CCoinsDB
//

bool CCoinsDB::HaveCoins(uint256 hash) {
    assert(!fClient);
    return Exists(make_pair('c', hash));
}

bool CCoinsDB::ReadCoins(uint256 hash, CCoins &coins) {
    assert(!fClient);
    return Read(make_pair('c', hash), coins);
}

bool CCoinsDB::WriteCoins(uint256 hash, const CCoins &coins) {
    assert(!fClient);
    if (coins.IsPruned())
        return Erase(make_pair('c', hash));
    else
        return Write(make_pair('c', hash), coins);
}

bool CChainDB::WriteBlockIndex(const CDiskBlockIndex& blockindex)
{
    return Write(make_pair('b', blockindex.GetBlockHash()), blockindex);
}

bool CCoinsDB::ReadHashBestChain(uint256& hashBestChain)
{
    return Read('B', hashBestChain);
}

bool CCoinsDB::WriteHashBestChain(uint256 hashBestChain)
{
    return Write('B', hashBestChain);
}

bool CChainDB::ReadBestInvalidWork(CBigNum& bnBestInvalidWork)
{
    return Read('I', bnBestInvalidWork);
}

bool CChainDB::WriteBestInvalidWork(CBigNum bnBestInvalidWork)
{
    return Write('I', bnBestInvalidWork);
}

bool CChainDB::WriteBlockFileInfo(int nFile, const CBlockFileInfo &info) {
    return Write(make_pair('f', nFile), info);
}

bool CChainDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {
    return Read(make_pair('f', nFile), info);
}

bool CChainDB::WriteLastBlockFile(int nFile) {
    return Write('l', nFile);
}

bool CChainDB::ReadLastBlockFile(int &nFile) {
    return Read('l', nFile);
}

CCoinsViewDB::CCoinsViewDB() : db("cr+") {}
bool CCoinsViewDB::GetCoins(uint256 txid, CCoins &coins) { return db.ReadCoins(txid, coins); }
bool CCoinsViewDB::SetCoins(uint256 txid, const CCoins &coins) { return db.WriteCoins(txid, coins); }
bool CCoinsViewDB::HaveCoins(uint256 txid) { return db.HaveCoins(txid); }
CBlockIndex *CCoinsViewDB::GetBestBlock() {
    uint256 hashBestChain;
    if (!db.ReadHashBestChain(hashBestChain))
        return NULL;
    std::map<uint256, CBlockIndex*>::iterator it = mapBlockIndex.find(hashBestChain);
    if (it == mapBlockIndex.end())
        return NULL;
    return it->second;
}
bool CCoinsViewDB::SetBestBlock(CBlockIndex *pindex) { return db.WriteHashBestChain(pindex->GetBlockHash()); }
bool CCoinsViewDB::BatchWrite(const std::map<uint256, CCoins> &mapCoins, CBlockIndex *pindex) {
    printf("Committing %u changed transactions to coin database...\n", (unsigned int)mapCoins.size());

    if (!db.TxnBegin())
        return false;
    bool fOk = true;
    for (std::map<uint256, CCoins>::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++) {
        fOk = db.WriteCoins(it->first, it->second);
        if (!fOk)
            break;
    }
    if (fOk)
        fOk = db.WriteHashBestChain(pindex->GetBlockHash());

    if (!fOk)
        db.TxnAbort();
    else
        fOk = db.TxnCommit();

    return fOk;
}

CBlockIndex static * InsertBlockIndex(uint256 hash)
{
    if (hash == 0)
        return NULL;

    // Return existing
    map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hash);
    if (mi != mapBlockIndex.end())
        return (*mi).second;

    // Create new
    CBlockIndex* pindexNew = new CBlockIndex();
    if (!pindexNew)
        throw runtime_error("LoadBlockIndex() : new CBlockIndex failed");
    mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
    pindexNew->phashBlock = &((*mi).first);

    return pindexNew;
}

bool LoadBlockIndex(CChainDB &chaindb)
{
    if (!chaindb.LoadBlockIndexGuts())
        return false;

    if (fRequestShutdown)
        return true;

    // Calculate bnChainWork
    vector<pair<int, CBlockIndex*> > vSortedByHeight;
    vSortedByHeight.reserve(mapBlockIndex.size());
    BOOST_FOREACH(const PAIRTYPE(uint256, CBlockIndex*)& item, mapBlockIndex)
    {
        CBlockIndex* pindex = item.second;
        vSortedByHeight.push_back(make_pair(pindex->nHeight, pindex));
    }
    sort(vSortedByHeight.begin(), vSortedByHeight.end());
    BOOST_FOREACH(const PAIRTYPE(int, CBlockIndex*)& item, vSortedByHeight)
    {
        CBlockIndex* pindex = item.second;
        pindex->bnChainWork = (pindex->pprev ? pindex->pprev->bnChainWork : 0) + pindex->GetBlockWork();
    }

    // Load block file info
    chaindb.ReadLastBlockFile(nLastBlockFile);
    printf("LoadBlockIndex(): last block file = %i\n", nLastBlockFile);
    if (chaindb.ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile))
        printf("LoadBlockIndex(): last block file: %s\n", infoLastBlockFile.ToString().c_str());
 
    // Load hashBestChain pointer to end of best chain
    pindexBest = pcoinsTip->GetBestBlock();
    if (pindexBest == NULL)
    {
        if (pindexGenesisBlock == NULL)
            return true;
    }
    hashBestChain = pindexBest->GetBlockHash();
    nBestHeight = pindexBest->nHeight;
    bnBestChainWork = pindexBest->bnChainWork;

    // set 'next' pointers in best chain
    CBlockIndex *pindex = pindexBest;
    while(pindex != NULL && pindex->pprev != NULL) {
         CBlockIndex *pindexPrev = pindex->pprev;
         pindexPrev->pnext = pindex;
         pindex = pindexPrev;
    }
    printf("LoadBlockIndex(): hashBestChain=%s  height=%d date=%s\n",
        hashBestChain.ToString().substr(0,20).c_str(), nBestHeight,
        DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());

    // Load bnBestInvalidWork, OK if it doesn't exist
    chaindb.ReadBestInvalidWork(bnBestInvalidWork);

    // Verify blocks in the best chain
    int nCheckLevel = GetArg("-checklevel", 1);
    int nCheckDepth = GetArg( "-checkblocks", 2500);
    if (nCheckDepth == 0)
        nCheckDepth = 1000000000; // suffices until the year 19000
    if (nCheckDepth > nBestHeight)
        nCheckDepth = nBestHeight;
    printf("Verifying last %i blocks at level %i\n", nCheckDepth, nCheckLevel);
    CBlockIndex* pindexFork = NULL;
    for (CBlockIndex* pindex = pindexBest; pindex && pindex->pprev; pindex = pindex->pprev)
    {
        if (fRequestShutdown || pindex->nHeight < nBestHeight-nCheckDepth)
            break;
        CBlock block;
        if (!block.ReadFromDisk(pindex))
            return error("LoadBlockIndex() : block.ReadFromDisk failed");
        // check level 1: verify block validity
        if (nCheckLevel>0 && !block.CheckBlock())
        {
            printf("LoadBlockIndex() : *** found bad block at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString().c_str());
            pindexFork = pindex->pprev;
        }
        // TODO: stronger verifications
    }
    if (pindexFork && !fRequestShutdown)
    {
        // TODO: reorg back
        return error("LoadBlockIndex(): chain database corrupted");
    }

    return true;
}



bool CChainDB::LoadBlockIndexGuts()
{
    // Get database cursor
    Dbc* pcursor = GetCursor();
    if (!pcursor)
        return false;

    // Load mapBlockIndex
    unsigned int fFlags = DB_SET_RANGE;
    loop
    {
        // Read next record
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        if (fFlags == DB_SET_RANGE)
            ssKey << make_pair('b', uint256(0));
        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
        int ret = ReadAtCursor(pcursor, ssKey, ssValue, fFlags);
        fFlags = DB_NEXT;
        if (ret == DB_NOTFOUND)
            break;
        else if (ret != 0)
            return false;

        // Unserialize

        try {
        char chType;
        ssKey >> chType;
        if (chType == 'b' && !fRequestShutdown)
        {
            CDiskBlockIndex diskindex;
            ssValue >> diskindex;

            // Construct block index object
            CBlockIndex* pindexNew = InsertBlockIndex(diskindex.GetBlockHash());
            pindexNew->pprev          = InsertBlockIndex(diskindex.hashPrev);
            pindexNew->nHeight        = diskindex.nHeight;
            pindexNew->pos            = diskindex.pos;
            pindexNew->nUndoPos       = diskindex.nUndoPos;
            pindexNew->nVersion       = diskindex.nVersion;
            pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
            pindexNew->nTime          = diskindex.nTime;
            pindexNew->nBits          = diskindex.nBits;
            pindexNew->nNonce         = diskindex.nNonce;

            // Watch for genesis block
            if (pindexGenesisBlock == NULL && diskindex.GetBlockHash() == hashGenesisBlock)
                pindexGenesisBlock = pindexNew;

            if (!pindexNew->CheckIndex())
                return error("LoadBlockIndex() : CheckIndex failed at %d", pindexNew->nHeight);
        }
        else
        {
            break; // if shutdown requested or finished loading block index
        }
        }    // try
        catch (std::exception &e) {
            return error("%s() : deserialize error", __PRETTY_FUNCTION__);
        }
    }
    pcursor->close();

    return true;
}





//
// CAddrDB
//


CAddrDB::CAddrDB()
{
    pathAddr = GetDataDir() / "peers.dat";
}

bool CAddrDB::Write(const CAddrMan& addr)
{
    // Generate random temporary filename
    unsigned short randv = 0;
    RAND_bytes((unsigned char *)&randv, sizeof(randv));
    std::string tmpfn = strprintf("peers.dat.%04x", randv);

    // serialize addresses, checksum data up to that point, then append csum
    CDataStream ssPeers(SER_DISK, CLIENT_VERSION);
    ssPeers << FLATDATA(pchMessageStart);
    ssPeers << addr;
    uint256 hash = Hash(ssPeers.begin(), ssPeers.end());
    ssPeers << hash;

    // open temp output file, and associate with CAutoFile
    boost::filesystem::path pathTmp = GetDataDir() / tmpfn;
    FILE *file = fopen(pathTmp.string().c_str(), "wb");
    CAutoFile fileout = CAutoFile(file, SER_DISK, CLIENT_VERSION);
    if (!fileout)
        return error("CAddrman::Write() : open failed");

    // Write and commit header, data
    try {
        fileout << ssPeers;
    }
    catch (std::exception &e) {
        return error("CAddrman::Write() : I/O error");
    }
    FileCommit(fileout);
    fileout.fclose();

    // replace existing peers.dat, if any, with new peers.dat.XXXX
    if (!RenameOver(pathTmp, pathAddr))
        return error("CAddrman::Write() : Rename-into-place failed");

    return true;
}

bool CAddrDB::Read(CAddrMan& addr)
{
    // open input file, and associate with CAutoFile
    FILE *file = fopen(pathAddr.string().c_str(), "rb");
    CAutoFile filein = CAutoFile(file, SER_DISK, CLIENT_VERSION);
    if (!filein)
        return error("CAddrman::Read() : open failed");

    // use file size to size memory buffer
    int fileSize = GetFilesize(filein);
    int dataSize = fileSize - sizeof(uint256);
    vector<unsigned char> vchData;
    vchData.resize(dataSize);
    uint256 hashIn;

    // read data and checksum from file
    try {
        filein.read((char *)&vchData[0], dataSize);
        filein >> hashIn;
    }
    catch (std::exception &e) {
        return error("CAddrman::Read() 2 : I/O error or stream data corrupted");
    }
    filein.fclose();

    CDataStream ssPeers(vchData, SER_DISK, CLIENT_VERSION);

    // verify stored checksum matches input data
    uint256 hashTmp = Hash(ssPeers.begin(), ssPeers.end());
    if (hashIn != hashTmp)
        return error("CAddrman::Read() : checksum mismatch; data corrupted");

    // de-serialize address data
    unsigned char pchMsgTmp[4];
    try {
        ssPeers >> FLATDATA(pchMsgTmp);
        ssPeers >> addr;
    }
    catch (std::exception &e) {
        return error("CAddrman::Read() : I/O error or stream data corrupted");
    }

    // finally, verify the network matches ours
    if (memcmp(pchMsgTmp, pchMessageStart, sizeof(pchMsgTmp)))
        return error("CAddrman::Read() : invalid network magic number");

    return true;
}