summaryrefslogtreecommitdiffstats
path: root/common/storage_lmdb.cpp
blob: 9789c612f2535f0e10732a4652e31caee2e03914 (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
/*
 * Copyright (C) 2014 Christian Mollekopf <chrigi_1@fastmail.fm>
 * Copyright (C) 2014 Aaron Seigo <aseigo@kde.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) version 3, or any
 * later version accepted by the membership of KDE e.V. (or its
 * successor approved by the membership of KDE e.V.), which shall
 * act as a proxy defined in Section 6 of version 3 of the license.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "storage.h"

#include <iostream>

#include <QAtomicInt>
#include <QDebug>
#include <QDir>
#include <QReadWriteLock>
#include <QString>
#include <QTime>
#include <QMutex>
#include <valgrind.h>

#include <lmdb.h>
#include "log.h"

SINK_DEBUG_AREA("storage")
// SINK_DEBUG_COMPONENT(d->storageRoot.toLatin1() + '/' + d->name.toLatin1())

namespace Sink {
namespace Storage {

extern QMutex sMutex;
extern QHash<QString, MDB_env *> sEnvironments;


QMutex sMutex;
QHash<QString, MDB_env *> sEnvironments;

int getErrorCode(int e)
{
    switch (e) {
        case MDB_NOTFOUND:
            return DataStore::ErrorCodes::NotFound;
        default:
            break;
    }
    return -1;
}

class DataStore::NamedDatabase::Private
{
public:
    Private(const QByteArray &_db, bool _allowDuplicates, const std::function<void(const DataStore::Error &error)> &_defaultErrorHandler, const QString &_name, MDB_txn *_txn)
        : db(_db), transaction(_txn), allowDuplicates(_allowDuplicates), defaultErrorHandler(_defaultErrorHandler), name(_name)
    {
    }

    ~Private()
    {
    }

    QByteArray db;
    MDB_txn *transaction;
    MDB_dbi dbi;
    bool allowDuplicates;
    std::function<void(const DataStore::Error &error)> defaultErrorHandler;
    QString name;

    bool openDatabase(bool readOnly, std::function<void(const DataStore::Error &error)> errorHandler)
    {
        unsigned int flags = 0;
        if (!readOnly) {
            flags |= MDB_CREATE;
        }
        if (allowDuplicates) {
            flags |= MDB_DUPSORT;
        }
        Q_ASSERT(transaction);
        if (const int rc = mdb_dbi_open(transaction, db.constData(), flags, &dbi)) {
            dbi = 0;
            transaction = 0;
            // The database is not existing, ignore in read-only mode
            if (!(readOnly && rc == MDB_NOTFOUND)) {
                Error error(name.toLatin1(), ErrorCodes::GenericError, "Error while opening database: " + QByteArray(mdb_strerror(rc)));
                errorHandler ? errorHandler(error) : defaultErrorHandler(error);
            }
            return false;
        }
        return true;
    }
};

DataStore::NamedDatabase::NamedDatabase() : d(nullptr)
{
}

DataStore::NamedDatabase::NamedDatabase(NamedDatabase::Private *prv) : d(prv)
{
}

DataStore::NamedDatabase::NamedDatabase(NamedDatabase &&other) : d(nullptr)
{
    *this = std::move(other);
}

DataStore::NamedDatabase &DataStore::NamedDatabase::operator=(DataStore::NamedDatabase &&other)
{
    if (&other != this) {
        delete d;
        d = other.d;
        other.d = nullptr;
    }
    return *this;
}

DataStore::NamedDatabase::~NamedDatabase()
{
    delete d;
}

bool DataStore::NamedDatabase::write(const QByteArray &sKey, const QByteArray &sValue, const std::function<void(const DataStore::Error &error)> &errorHandler)
{
    if (!d || !d->transaction) {
        Error error("", ErrorCodes::GenericError, "Not open");
        if (d) {
            errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        }
        return false;
    }
    const void *keyPtr = sKey.data();
    const size_t keySize = sKey.size();
    const void *valuePtr = sValue.data();
    const size_t valueSize = sValue.size();

    if (!keyPtr || keySize == 0) {
        Error error(d->name.toLatin1() + d->db, ErrorCodes::GenericError, "Tried to write empty key.");
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        return false;
    }

    int rc;
    MDB_val key, data;
    key.mv_size = keySize;
    key.mv_data = const_cast<void *>(keyPtr);
    data.mv_size = valueSize;
    data.mv_data = const_cast<void *>(valuePtr);
    rc = mdb_put(d->transaction, d->dbi, &key, &data, 0);

    if (rc) {
        Error error(d->name.toLatin1() + d->db, ErrorCodes::GenericError, "mdb_put: " + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
    }

    return !rc;
}

void DataStore::NamedDatabase::remove(const QByteArray &k, const std::function<void(const DataStore::Error &error)> &errorHandler)
{
    remove(k, QByteArray(), errorHandler);
}

void DataStore::NamedDatabase::remove(const QByteArray &k, const QByteArray &value, const std::function<void(const DataStore::Error &error)> &errorHandler)
{
    if (!d || !d->transaction) {
        if (d) {
            Error error(d->name.toLatin1() + d->db, ErrorCodes::GenericError, "Not open");
            errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        }
        return;
    }

    int rc;
    MDB_val key;
    key.mv_size = k.size();
    key.mv_data = const_cast<void *>(static_cast<const void *>(k.data()));
    if (value.isEmpty()) {
        rc = mdb_del(d->transaction, d->dbi, &key, 0);
    } else {
        MDB_val data;
        data.mv_size = value.size();
        data.mv_data = const_cast<void *>(static_cast<const void *>(value.data()));
        rc = mdb_del(d->transaction, d->dbi, &key, &data);
    }

    if (rc) {
        auto errorCode = ErrorCodes::GenericError;
        if (rc == MDB_NOTFOUND) {
            errorCode = ErrorCodes::NotFound;
        }
        Error error(d->name.toLatin1() + d->db, errorCode, QString("Error on mdb_del: %1 %2").arg(rc).arg(mdb_strerror(rc)).toLatin1());
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
    }
}

int DataStore::NamedDatabase::scan(const QByteArray &k, const std::function<bool(const QByteArray &key, const QByteArray &value)> &resultHandler,
    const std::function<void(const DataStore::Error &error)> &errorHandler, bool findSubstringKeys, bool skipInternalKeys) const
{
    if (!d || !d->transaction) {
        // Not an error. We rely on this to read nothing from non-existing databases.
        return 0;
    }

    int rc;
    MDB_val key;
    MDB_val data;
    MDB_cursor *cursor;

    key.mv_data = (void *)k.constData();
    key.mv_size = k.size();

    rc = mdb_cursor_open(d->transaction, d->dbi, &cursor);
    if (rc) {
        Error error(d->name.toLatin1() + d->db, getErrorCode(rc), QByteArray("Error during mdb_cursor open: ") + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        return 0;
    }

    int numberOfRetrievedValues = 0;

    if (k.isEmpty() || d->allowDuplicates || findSubstringKeys) {
        MDB_cursor_op op = d->allowDuplicates ? MDB_SET : MDB_FIRST;
        if (findSubstringKeys) {
            op = MDB_SET_RANGE;
        }
        if ((rc = mdb_cursor_get(cursor, &key, &data, op)) == 0) {
            const auto current = QByteArray::fromRawData((char *)key.mv_data, key.mv_size);
            // The first lookup will find a key that is equal or greather than our key
            if (current.startsWith(k)) {
                const bool callResultHandler =  !(skipInternalKeys && isInternalKey(current));
                if (callResultHandler) {
                    numberOfRetrievedValues++;
                }
                if (!callResultHandler || resultHandler(current, QByteArray::fromRawData((char *)data.mv_data, data.mv_size))) {
                    if (findSubstringKeys) {
                        // Reset the key to what we search for
                        key.mv_data = (void *)k.constData();
                        key.mv_size = k.size();
                    }
                    MDB_cursor_op nextOp = (d->allowDuplicates && !findSubstringKeys) ? MDB_NEXT_DUP : MDB_NEXT;
                    while ((rc = mdb_cursor_get(cursor, &key, &data, nextOp)) == 0) {
                        const auto current = QByteArray::fromRawData((char *)key.mv_data, key.mv_size);
                        // Every consequitive lookup simply iterates through the list
                        if (current.startsWith(k)) {
                            const bool callResultHandler =  !(skipInternalKeys && isInternalKey(current));
                            if (callResultHandler) {
                                numberOfRetrievedValues++;
                                if (!resultHandler(current, QByteArray::fromRawData((char *)data.mv_data, data.mv_size))) {
                                    break;
                                }
                            }
                        }
                    }
                }
            }
        }

        // We never find the last value
        if (rc == MDB_NOTFOUND) {
            rc = 0;
        }
    } else {
        if ((rc = mdb_cursor_get(cursor, &key, &data, MDB_SET)) == 0) {
            numberOfRetrievedValues++;
            resultHandler(QByteArray::fromRawData((char *)key.mv_data, key.mv_size), QByteArray::fromRawData((char *)data.mv_data, data.mv_size));
        }
    }

    mdb_cursor_close(cursor);

    if (rc) {
        Error error(d->name.toLatin1() + d->db, getErrorCode(rc), QByteArray("Key: ") + k + " : " + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
    }

    return numberOfRetrievedValues;
}

void DataStore::NamedDatabase::findLatest(const QByteArray &k, const std::function<void(const QByteArray &key, const QByteArray &value)> &resultHandler,
    const std::function<void(const DataStore::Error &error)> &errorHandler) const
{
    if (!d || !d->transaction) {
        // Not an error. We rely on this to read nothing from non-existing databases.
        return;
    }

    int rc;
    MDB_val key;
    MDB_val data;
    MDB_cursor *cursor;

    key.mv_data = (void *)k.constData();
    key.mv_size = k.size();

    rc = mdb_cursor_open(d->transaction, d->dbi, &cursor);
    if (rc) {
        Error error(d->name.toLatin1() + d->db, getErrorCode(rc), QByteArray("Error during mdb_cursor open: ") + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        return;
    }

    bool foundValue = false;
    MDB_cursor_op op = MDB_SET_RANGE;
    if ((rc = mdb_cursor_get(cursor, &key, &data, op)) == 0) {
        // The first lookup will find a key that is equal or greather than our key
        if (QByteArray::fromRawData((char *)key.mv_data, key.mv_size).startsWith(k)) {
            bool advanced = false;
            while (QByteArray::fromRawData((char *)key.mv_data, key.mv_size).startsWith(k)) {
                advanced = true;
                MDB_cursor_op nextOp = MDB_NEXT;
                rc = mdb_cursor_get(cursor, &key, &data, nextOp);
                if (rc) {
                    break;
                }
            }
            if (advanced) {
                MDB_cursor_op prefOp = MDB_PREV;
                // We read past the end above, just take the last value
                if (rc == MDB_NOTFOUND) {
                    prefOp = MDB_LAST;
                }
                rc = mdb_cursor_get(cursor, &key, &data, prefOp);
                foundValue = true;
                resultHandler(QByteArray::fromRawData((char *)key.mv_data, key.mv_size), QByteArray::fromRawData((char *)data.mv_data, data.mv_size));
            }
        }
    }

    // We never find the last value
    if (rc == MDB_NOTFOUND) {
        rc = 0;
    }

    mdb_cursor_close(cursor);

    if (rc) {
        Error error(d->name.toLatin1(), getErrorCode(rc), QByteArray("Key: ") + k + " : " + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
    } else if (!foundValue) {
        Error error(d->name.toLatin1(), 1, QByteArray("Key: ") + k + " : No value found");
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
    }

    return;
}

qint64 DataStore::NamedDatabase::getSize()
{
    if (!d || !d->transaction) {
        return -1;
    }

    int rc;
    MDB_stat stat;
    rc = mdb_stat(d->transaction, d->dbi, &stat);
    if (rc) {
        SinkWarning() << "Something went wrong " << QByteArray(mdb_strerror(rc));
    }
    // std::cout << "overflow_pages: " << stat.ms_overflow_pages << std::endl;
    // std::cout << "page size: " << stat.ms_psize << std::endl;
    // std::cout << "branch_pages: " << stat.ms_branch_pages << std::endl;
    // std::cout << "leaf_pages: " << stat.ms_leaf_pages << std::endl;
    // std::cout << "depth: " << stat.ms_depth << std::endl;
    // std::cout << "entries: " << stat.ms_entries << std::endl;
    return stat.ms_psize * (stat.ms_leaf_pages + stat.ms_branch_pages + stat.ms_overflow_pages);
}


class DataStore::Transaction::Private
{
public:
    Private(bool _requestRead, const std::function<void(const DataStore::Error &error)> &_defaultErrorHandler, const QString &_name, MDB_env *_env)
        : env(_env), transaction(nullptr), requestedRead(_requestRead), defaultErrorHandler(_defaultErrorHandler), name(_name), implicitCommit(false), error(false), modificationCounter(0)
    {
    }
    ~Private()
    {
    }

    MDB_env *env;
    MDB_txn *transaction;
    MDB_dbi dbi;
    bool requestedRead;
    std::function<void(const DataStore::Error &error)> defaultErrorHandler;
    QString name;
    bool implicitCommit;
    bool error;
    int modificationCounter;

    void startTransaction()
    {
        Q_ASSERT(!transaction);
        // auto f = [](const char *msg, void *ctx) -> int {
        //     qDebug() << msg;
        //     return 0;
        // };
        // mdb_reader_list(env, f, nullptr);
        // Trace_area("storage." + name.toLatin1()) << "Opening transaction " << requestedRead;
        const int rc = mdb_txn_begin(env, NULL, requestedRead ? MDB_RDONLY : 0, &transaction);
        // Trace_area("storage." + name.toLatin1()) << "Started transaction " << mdb_txn_id(transaction) << transaction;
        if (rc) {
            defaultErrorHandler(Error(name.toLatin1(), ErrorCodes::GenericError, "Error while opening transaction: " + QByteArray(mdb_strerror(rc))));
        }
    }
};

DataStore::Transaction::Transaction() : d(nullptr)
{
}

DataStore::Transaction::Transaction(Transaction::Private *prv) : d(prv)
{
    d->startTransaction();
}

DataStore::Transaction::Transaction(Transaction &&other) : d(nullptr)
{
    *this = std::move(other);
}

DataStore::Transaction &DataStore::Transaction::operator=(DataStore::Transaction &&other)
{
    if (&other != this) {
        delete d;
        d = other.d;
        other.d = nullptr;
    }
    return *this;
}

DataStore::Transaction::~Transaction()
{
    if (d && d->transaction) {
        if (d->implicitCommit && !d->error) {
            commit();
        } else {
            // Trace_area("storage." + d->name.toLatin1()) << "Aborting transaction" << mdb_txn_id(d->transaction) << d->transaction;
            abort();
        }
    }
    delete d;
}

DataStore::Transaction::operator bool() const
{
    return (d && d->transaction);
}

bool DataStore::Transaction::commit(const std::function<void(const DataStore::Error &error)> &errorHandler)
{
    if (!d || !d->transaction) {
        return false;
    }

    // Trace_area("storage." + d->name.toLatin1()) << "Committing transaction" << mdb_txn_id(d->transaction) << d->transaction;
    Q_ASSERT(sEnvironments.values().contains(d->env));
    const int rc = mdb_txn_commit(d->transaction);
    if (rc) {
        abort();
        Error error(d->name.toLatin1(), ErrorCodes::TransactionError, "Error during transaction commit: " + QByteArray(mdb_strerror(rc)));
        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
        //If transactions start failing we're in an unrecoverable situation (i.e. out of diskspace). So throw an exception that will terminate the application.
        throw std::runtime_error("Fatal error while committing transaction.");
    }
    d->transaction = nullptr;

    return !rc;
}

void DataStore::Transaction::abort()
{
    if (!d || !d->transaction) {
        return;
    }

    // Trace_area("storage." + d->name.toLatin1()) << "Aborting transaction" << mdb_txn_id(d->transaction) << d->transaction;
    Q_ASSERT(sEnvironments.values().contains(d->env));
    mdb_txn_abort(d->transaction);
    d->transaction = nullptr;
}

//Ensure that we opened the correct database by comparing the expected identifier with the one
//we write to the database on first open.
static bool ensureCorrectDb(DataStore::NamedDatabase &database, const QByteArray &db, bool readOnly)
{
    bool openedTheWrongDatabase = false;
    auto count = database.scan("__internal_dbname", [db, &openedTheWrongDatabase](const QByteArray &key, const QByteArray &value) ->bool {
        if (value != db) {
            SinkWarning() << "Opened the wrong database, got " << value << " instead of " << db;
            openedTheWrongDatabase = true;
        }
        return false;
    },
    [](const DataStore::Error &error) -> bool{
        return false;
    }, false);
    //This is the first time we open this database in a write transaction, write the db name
    if (!count) {
        if (!readOnly) {
            database.write("__internal_dbname", db);
        }
    }
    return !openedTheWrongDatabase;
}

bool DataStore::Transaction::validateNamedDatabases()
{
    auto databases = getDatabaseNames();
    for (const auto &dbName : databases) {
        auto db = openDatabase(dbName);
        if (!db) {
            SinkWarning() << "Failed to open the database: " << dbName;
            return false;
        }
    }
    return true;
}

DataStore::NamedDatabase DataStore::Transaction::openDatabase(const QByteArray &db, const std::function<void(const DataStore::Error &error)> &errorHandler, bool allowDuplicates) const
{
    if (!d) {
        SinkError() << "Tried to open database on invalid transaction: " << db;
        return DataStore::NamedDatabase();
    }
    Q_ASSERT(d->transaction);
    // We don't now if anything changed
    d->implicitCommit = true;
    auto p = new DataStore::NamedDatabase::Private(db, allowDuplicates, d->defaultErrorHandler, d->name, d->transaction);
    if (!p->openDatabase(d->requestedRead, errorHandler)) {
        delete p;
        return DataStore::NamedDatabase();
    }
    auto database = DataStore::NamedDatabase(p);
    if (!ensureCorrectDb(database, db, d->requestedRead)) {
        SinkWarning() << "Failed to open the database" << db;
        return DataStore::NamedDatabase();
    }
    return database;
}

QList<QByteArray> DataStore::Transaction::getDatabaseNames() const
{
    if (!d) {
        SinkWarning() << "Invalid transaction";
        return QList<QByteArray>();
    }

    int rc;
    QList<QByteArray> list;
    if ((rc = mdb_dbi_open(d->transaction, nullptr, 0, &d->dbi) == 0)) {
        MDB_val key;
        MDB_val data;
        MDB_cursor *cursor;

        mdb_cursor_open(d->transaction, d->dbi, &cursor);
        if ((rc = mdb_cursor_get(cursor, &key, &data, MDB_FIRST)) == 0) {
            list << QByteArray::fromRawData((char *)key.mv_data, key.mv_size);
            while ((rc = mdb_cursor_get(cursor, &key, &data, MDB_NEXT)) == 0) {
                list << QByteArray::fromRawData((char *)key.mv_data, key.mv_size);
            }
        } else {
            //Normal if we don't have any databases yet
            if (rc == MDB_NOTFOUND) {
                rc = 0;
            }
            if (rc) {
                SinkWarning() << "Failed to get a value" << rc;
            }
        }
        mdb_cursor_close(cursor);
    } else {
        SinkWarning() << "Failed to open db" << rc << QByteArray(mdb_strerror(rc));
    }
    return list;
}


class DataStore::Private
{
public:
    Private(const QString &s, const QString &n, AccessMode m);
    ~Private();

    QString storageRoot;
    QString name;

    MDB_env *env;
    AccessMode mode;
};

DataStore::Private::Private(const QString &s, const QString &n, AccessMode m) : storageRoot(s), name(n), env(0), mode(m)
{
    const QString fullPath(storageRoot + '/' + name);
    QFileInfo dirInfo(fullPath);
    if (!dirInfo.exists() && mode == ReadWrite) {
        QDir().mkpath(fullPath);
        dirInfo.refresh();
    }
    Sink::Log::Context logCtx{n.toLatin1()};
    if (mode == ReadWrite && !dirInfo.permission(QFile::WriteOwner)) {
        qCritical() << fullPath << "does not have write permissions. Aborting";
    } else if (dirInfo.exists()) {
        // Ensure the environment is only created once
        QMutexLocker locker(&sMutex);

        /*
        * It seems we can only ever have one environment open in the process.
        * Otherwise multi-threading breaks.
        */
        env = sEnvironments.value(fullPath);
        if (!env) {
            int rc = 0;
            if ((rc = mdb_env_create(&env))) {
                // TODO: handle error
                SinkWarningCtx(logCtx) << "mdb_env_create: " << rc << " " << mdb_strerror(rc);
            } else {
                mdb_env_set_maxdbs(env, 50);
                unsigned int flags = MDB_NOTLS;
                if (mode == ReadOnly) {
                    flags |= MDB_RDONLY;
                }
                if ((rc = mdb_env_open(env, fullPath.toStdString().data(), flags, 0664))) {
                    SinkWarningCtx(logCtx) << "mdb_env_open: " << rc << ":" << mdb_strerror(rc);
                    mdb_env_close(env);
                    env = 0;
                } else {
                    if (RUNNING_ON_VALGRIND) {
                        // In order to run valgrind this size must be smaller than half your available RAM
                        // https://github.com/BVLC/caffe/issues/2404
                        const size_t dbSize = (size_t)10485760 * (size_t)1000; // 1MB * 1000
                        mdb_env_set_mapsize(env, dbSize);
                    } else {
                        // FIXME: dynamic resize
                        const size_t dbSize = (size_t)10485760 * (size_t)8000; // 1MB * 8000
                        mdb_env_set_mapsize(env, dbSize);
                    }
                    sEnvironments.insert(fullPath, env);
                }
            }
        }
    }
}

DataStore::Private::~Private()
{
    //We never close the environment (unless we remove the db), since we should only open the environment once per process (as per lmdb docs)
    //and create storage instance from all over the place. Thus, we're not closing it here on purpose.
}

DataStore::DataStore(const QString &storageRoot, const QString &name, AccessMode mode) : d(new Private(storageRoot, name, mode))
{
}

DataStore::~DataStore()
{
    delete d;
}

bool DataStore::exists() const
{
    return (d->env != 0);
}

DataStore::Transaction DataStore::createTransaction(AccessMode type, const std::function<void(const DataStore::Error &error)> &errorHandlerArg)
{
    auto errorHandler = errorHandlerArg ? errorHandlerArg : defaultErrorHandler();
    if (!d->env) {
        errorHandler(Error(d->name.toLatin1(), ErrorCodes::GenericError, "Failed to create transaction: Missing database environment"));
        return Transaction();
    }

    bool requestedRead = type == ReadOnly;

    if (d->mode == ReadOnly && !requestedRead) {
        errorHandler(Error(d->name.toLatin1(), ErrorCodes::GenericError, "Failed to create transaction: Requested read/write transaction in read-only mode."));
        return Transaction();
    }

    return Transaction(new Transaction::Private(requestedRead, defaultErrorHandler(), d->name, d->env));
}

qint64 DataStore::diskUsage() const
{
    QFileInfo info(d->storageRoot + '/' + d->name + "/data.mdb");
    if (!info.exists()) {
        SinkWarning() << "Tried to get filesize for non-existant file: " << info.path();
    }
    return info.size();
}

void DataStore::removeFromDisk() const
{
    const QString fullPath(d->storageRoot + '/' + d->name);
    QMutexLocker locker(&sMutex);
    SinkTrace() << "Removing database from disk: " << fullPath;
    sEnvironments.take(fullPath);
    auto env = sEnvironments.take(fullPath);
    mdb_env_close(env);
    QDir dir(fullPath);
    if (!dir.removeRecursively()) {
        Error error(d->name.toLatin1(), ErrorCodes::GenericError, QString("Failed to remove directory %1 %2").arg(d->storageRoot).arg(d->name).toLatin1());
        defaultErrorHandler()(error);
    }
}

void DataStore::clearEnv()
{
    for (auto env : sEnvironments) {
        mdb_env_close(env);
    }
    sEnvironments.clear();
}

}
} // namespace Sink