summary refs log tree commit diff
path: root/db2/include/db_cxx.h
blob: 506aed845ccb2df875a5854fdfc0aff6c911c183 (plain) (blame)
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
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997
 *	Sleepycat Software.  All rights reserved.
 *
 *	@(#)db_cxx.h	10.7 (Sleepycat) 8/22/97
 */

#ifndef _DB_CXX_H_
#define _DB_CXX_H_

//
// C++ assumptions:
//
// To ensure portability to many platforms, both new and old, we make
// few assumptions about the C++ compiler and library.  For example,
// we do not expect STL, templates or namespaces to be available.  The
// "newest" C++ feature used is exceptions, which are used liberally
// to transmit error information.  Even the use of exceptions can be
// disabled at runtime, see setErrorModel().
//
// C++ naming conventions:
//
//  - All top level class names start with Db.
//  - All class members start with lower case letter.
//  - All private data members are suffixed with underscore.
//  - Use underscores to divide names into multiple words.
//  - Simple data accessors are named with get_ or set_ prefix.
//  - All method names are taken from names of functions in the C
//    layer of db (usually by dropping a prefix like "db_").
//    These methods have the same argument types and order,
//    other than dropping the explicit arg that acts as "this".
//
// As a rule, each DbFoo object has exactly one underlying DB_FOO struct
// (defined in db.h) associated with it.  In many cases, we inherit directly
// from the DB_FOO structure to make this relationship explicit.  Often,
// the underlying C layer allocates and deallocates these structures, so
// there is no easy way to add any data to the DbFoo class.  When you see
// a comment about whether data is permitted to be added, this is what
// is going on.  Of course, if we need to add data to such C++ classes
// in the future, we will arrange to have an indirect pointer to the
// DB_FOO struct (as some of the classes already have).
//


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Forward declarations
//

#include "db.h"

class Db;                                        // forward
class Dbc;                                       // forward
class DbEnv;                                     // forward
class DbException;                               // forward
class DbInfo;                                    // forward
class DbLock;                                    // forward
class DbLockTab;                                 // forward
class DbLog;                                     // forward
class DbLsn;                                     // forward
class DbMpool;                                   // forward
class DbMpoolFile;                               // forward
class Dbt;                                       // forward
class DbTxn;                                     // forward
class DbTxnMgr;                                  // forward

////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Mechanisms for declaring classes
//

//
// Every class defined in this file has an _exported next to the class name.
// This is needed for WinTel machines so that the class methods can
// be exported or imported in a DLL as appropriate.  Users of the DLL
// use the define DB_USE_DLL.  When the DLL is built, DB_CREATE_DLL
// must be defined.
//
#if defined(_MSC_VER)

#  if defined(DB_CREATE_DLL)
#    define _exported __declspec(dllexport)      // creator of dll
#  elif defined(DB_USE_DLL)
#    define _exported __declspec(dllimport)      // user of dll
#  else
#    define _exported                            // static lib creator or user
#  endif

#else

#  define _exported

#endif

// DEFINE_DB_CLASS defines an imp_ data member and imp() accessor.
// The underlying type is a pointer to an opaque *Imp class, that
// gets converted to the correct implementation class by the implementation.
//
// Since these defines use "private/public" labels, and leave the access
// being "private", we always use these by convention before any data
// members in the private section of a class.  Keeping them in the
// private section also emphasizes that they are off limits to user code.
//
#define DEFINE_DB_CLASS(name) \
    public: class name##Imp* imp() { return imp_; } \
    public: const class name##Imp* imp() const { return imp_; } \
    private: class name##Imp* imp_


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Turn off inappropriate compiler warnings
//

#ifdef _MSC_VER

// These are level 4 warnings that are explicitly disabled.
// With Visual C++, by default you do not see above level 3 unless
// you use /W4.  But we like to compile with the highest level
// warnings to catch other errors.
//
// 4201: nameless struct/union
//       triggered by standard include file <winnt.h>
//
// 4514: unreferenced inline function has been removed
//       certain include files in MSVC define methods that are not called
//
#pragma warning(disable: 4201 4514)

#endif

////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Exception classes
//

// Almost any error in the DB library throws a DbException.
// Every exception should be considered an abnormality
// (e.g. bug, misuse of DB, file system error).
//
// NOTE: We would like to inherit from class exception and
//       let it handle what(), but there are
//       MSVC++ problems when <exception> is included.
//
class _exported DbException
{
public:
    virtual ~DbException();
    DbException(int err);
    DbException(const char *description);
    DbException(const char *prefix, int err);
    DbException(const char *prefix1, const char *prefix2, int err);
    const int get_errno();
    virtual const char *what() const;

    DbException(const DbException &);
    DbException &operator = (const DbException &);

private:
    char *what_;
    int err_;                   // errno
};


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Lock classes
//

class _exported DbLock
{
    friend DbLockTab;

public:
    DbLock(unsigned int);
    DbLock();

    unsigned int get_lock_id();
    void set_lock_id(unsigned int);

    int put(DbLockTab *locktab);

    DbLock(const DbLock &);
    DbLock &operator = (const DbLock &);

protected:
    // We can add data to this class if needed
    // since its contained class is not allocated by db.
    // (see comment at top)

    DB_LOCK lock_;
};

class _exported DbLockTab
{
friend DbEnv;
public:
    int close();
    int detect(int atype, u_int32_t flags);
    int get(u_int32_t locker, int flags, const Dbt *obj,
            db_lockmode_t lock_mode, DbLock *lock);
    int id(u_int32_t *idp);
    int vec(u_int32_t locker, int flags, DB_LOCKREQ list[],
	    int nlist, DB_LOCKREQ **elistp);

    // Create or remove new locktab files
    //
    static int open(const char *dir, int flags, int mode,
                    DbEnv* dbenv, DbLockTab **regionp);
    static int unlink(const char *dir, int force, DbEnv* dbenv);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // copying not allowed
    //
    DbLockTab(const DbLockTab &);
    DbLockTab &operator = (const DbLockTab &);

    // Note: use DbLockTab::open() or DbEnv::get_lk_info()
    // to get pointers to a DbLockTab,
    // and call DbLockTab::close() rather than delete to release them.
    //
    DbLockTab();
    ~DbLockTab();

    DEFINE_DB_CLASS(DbLockTab);
};


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Log classes
//

class _exported DbLsn : protected DB_LSN
{
    friend DbLog;               // friendship needed to cast to base class
    friend DbMpool;
};

class _exported DbLog
{
friend DbEnv;
public:
    int archive(char **list[], int flags, void *(*db_malloc)(size_t));
    int close();
    static int compare(const DbLsn *lsn0, const DbLsn *lsn1);
    int file(DbLsn *lsn, char *namep, int len);
    int flush(const DbLsn *lsn);
    int get(DbLsn *lsn, Dbt *data, int flags);
    int put(DbLsn *lsn, const Dbt *data, int flags);

    // Normally these would be called register and unregister to
    // parallel the C interface, but "register" is a reserved word.
    //
    int db_register(Db *dbp, const char *name, u_int32_t *fidp);
    int db_unregister(u_int32_t fid);

    // Create or remove new log files
    //
    static int open(const char *dir, int flags, int mode,
                    DbEnv* dbenv, DbLog **regionp);
    static int unlink(const char *dir, int force, DbEnv* dbenv);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use DbLog::open() or DbEnv::get_lg_info()
    // to get pointers to a DbLog,
    // and call DbLog::close() rather than delete to release them.
    //
    DbLog();
    ~DbLog();

    // no copying
    DbLog(const DbLog &);
    operator = (const DbLog &);

    DEFINE_DB_CLASS(DbLog);
};


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Memory pool classes
//

class _exported DbMpoolFile
{
public:
    int close();
    int get(db_pgno_t *pgnoaddr, unsigned long flags, void *pagep);
    int put(void *pgaddr, unsigned long flags);
    int set(void *pgaddr, unsigned long flags);
    int sync();

    static int open(DbMpool *mp, const char *file,
                    int ftype, int flags, int mode,
                    size_t pagesize, int lsn_offset,
                    Dbt *pgcookie, u_int8_t *uid, DbMpoolFile **mpf);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use DbMpoolFile::open()
    // to get pointers to a DbMpoolFile,
    // and call DbMpoolFile::close() rather than delete to release them.
    //
    DbMpoolFile();

    // Shut g++ up.
protected:
    ~DbMpoolFile();

private:
    // no copying
    DbMpoolFile(const DbMpoolFile &);
    operator = (const DbMpoolFile &);

    DEFINE_DB_CLASS(DbMpoolFile);
};

class _exported DbMpool
{
friend DbEnv;
public:
    int close();

    // access to low level interface
    // Normally this would be called register to parallel
    // the C interface, but "register" is a reserved word.
    //
    int db_register(int ftype,
                    int (*pgin)(db_pgno_t pgno, void *pgaddr, DBT *pgcookie),
                    int (*pgout)(db_pgno_t pgno, void *pgaddr, DBT *pgcookie));

    int stat(DB_MPOOL_STAT **gsp, DB_MPOOL_FSTAT ***fsp,
             void *(*db_malloc)(size_t));
    int sync(DbLsn *lsn);

    // Create or remove new mpool files
    //
    static int open(const char *dir, int flags, int mode,
                    DbEnv* dbenv, DbMpool **regionp);
    static int unlink(const char *dir, int force, DbEnv* dbenv);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use DbMpool::open() or DbEnv::get_mp_info()
    // to get pointers to a DbMpool,
    // and call DbMpool::close() rather than delete to release them.
    //
    DbMpool();
    ~DbMpool();

    // no copying
    DbMpool(const DbMpool &);
    DbMpool &operator = (const DbMpool &);

    DEFINE_DB_CLASS(DbMpool);
};


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Transaction classes
//

class _exported DbTxnMgr
{
friend DbEnv;
public:
    int begin(DbTxn *pid, DbTxn **tid);
    int checkpoint(long kbyte, long min) const;
    int close();
    int stat(DB_TXN_STAT **statp, void *(*db_malloc)(size_t));

    // Create or remove new txnmgr files
    //
    static int open(const char *dir, int flags, int mode,
                    DbEnv* dbenv, DbTxnMgr **regionp);
    static int unlink(const char *dir, int force, DbEnv* dbenv);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use DbTxnMgr::open() or DbEnv::get_tx_info()
    // to get pointers to a DbTxnMgr,
    // and call DbTxnMgr::close() rather than delete to release them.
    //
    DbTxnMgr();
    ~DbTxnMgr();

    // no copying
    DbTxnMgr(const DbTxnMgr &);
    operator = (const DbTxnMgr &);

    DEFINE_DB_CLASS(DbTxnMgr);
};

class _exported DbTxn
{
friend DbTxnMgr;
public:
    int abort();
    int commit();
    u_int32_t id();
    int prepare();

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use DbTxnMgr::begin() to get pointers to a DbTxn,
    // and call DbTxn::abort() or DbTxn::commit rather than
    // delete to release them.
    //
    DbTxn();
    ~DbTxn();

    // no copying
    DbTxn(const DbTxn &);
    operator = (const DbTxn &);

    DEFINE_DB_CLASS(DbTxn);
};


////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Application classes
//

//
// A set of application options - define how this application uses
// the db library.
//
class _exported DbInfo : protected DB_INFO
{
    friend DbEnv;
    friend Db;

public:
    DbInfo();
    ~DbInfo();

    // Byte order.
    int	get_lorder() const;
    void set_lorder(int);

    // Underlying cache size.
    size_t get_cachesize() const;
    void set_cachesize(size_t);

    // Underlying page size.
    size_t get_pagesize() const;
    void set_pagesize(size_t);

    // Local heap allocation.
    typedef void *(*db_malloc_fcn)(size_t);
    db_malloc_fcn get_malloc() const;
    void set_malloc(db_malloc_fcn);

    ////////////////////////////////////////////////////////////////
    // Btree access method.

    // Maximum keys per page.
    int	get_bt_maxkey() const;
    void set_bt_maxkey(int);

    // Minimum keys per page.
    int	get_bt_minkey() const;
    void set_bt_minkey(int);

    // Comparison function.
    typedef int (*bt_compare_fcn)(const DBT *, const DBT *);
    bt_compare_fcn get_bt_compare() const;
    void set_bt_compare(bt_compare_fcn);

    // Prefix function.
    typedef size_t (*bt_prefix_fcn)(const DBT *, const DBT *);
    bt_prefix_fcn get_bt_prefix() const;
    void set_bt_prefix(bt_prefix_fcn);

    ////////////////////////////////////////////////////////////////
    // Hash access method.

    // Fill factor.
    unsigned int get_h_ffactor() const;
    void set_h_ffactor(unsigned int);

    // Number of elements.
    unsigned int get_h_nelem() const;
    void set_h_nelem(unsigned int);

    // Hash function.
    typedef u_int32_t (*h_hash_fcn)(const void *, u_int32_t);
    h_hash_fcn get_h_hash() const;
    void set_h_hash(h_hash_fcn);

    ////////////////////////////////////////////////////////////////
    // Recno access method.

    // Fixed-length padding byte.
    int	get_re_pad() const;
    void set_re_pad(int);

    // Variable-length delimiting byte.
    int	get_re_delim() const;
    void set_re_delim(int);

    // Length for fixed-length records.
    u_int32_t get_re_len() const;
    void set_re_len(u_int32_t);

    // Source file name.
    char *get_re_source() const;
    void set_re_source(char *);

    // Note: some flags are set as side effects of calling
    // above "set" methods.
    //
    u_int32_t get_flags() const;
    void set_flags(u_int32_t);


    // (deep) copying of this object is allowed.
    //
    DbInfo(const DbInfo &);
    DbInfo &operator = (const DbInfo &);

private:
    // We can add data to this class if needed
    // since parent class is not allocated by db.
    // (see comment at top)
};

//
// Base application class.  Provides functions for opening a database.
// User of this library can use this class as a starting point for
// developing a DB application - derive their application class from
// this one, add application control logic.
//
// Note that if you use the default constructor, you must explicitly
// call appinit() before any other db activity (e.g. opening files)
//
class _exported DbEnv : protected DB_ENV
{
friend DbTxnMgr;
friend DbLog;
friend DbLockTab;
friend DbMpool;
friend Db;

public:

    ~DbEnv();

    // This constructor can be used to immediately initialize the
    // application with these arguments.  Do not use it if you
    // need to set other parameters via the access methods.
    //
    DbEnv(const char *homeDir, char *const *db_config, int flags);

    // Use this constructor if you wish to *delay* the initialization
    // of the db library.  This is useful if you need to set
    // any particular parameters via the access methods below.
    // Then call appinit() to complete the initialization.
    //
    DbEnv();

    // Used in conjunction with the default constructor to
    // complete the initialization of the db library.
    //
    int appinit(const char *homeDir, char *const *db_config, int flags);

    ////////////////////////////////////////////////////////////////
    // simple get/set access methods
    //
    // If you are calling set_ methods, you need to
    // use the default constructor along with appinit().

    // Byte order.
    int	get_lorder() const;
    void set_lorder(int);

    // Error message callback.
    typedef void (*db_errcall_fcn)(const char *, char *);
    db_errcall_fcn get_errcall() const;
    void set_errcall(db_errcall_fcn);

    // Error message file stream.
    FILE *get_errfile() const;
    void set_errfile(FILE *);

    // Error message prefix.
    const char *get_errpfx() const;
    void set_errpfx(const char *);

    // Generate debugging messages.
    int get_verbose() const;
    void set_verbose(int);

    ////////////////////////////////////////////////////////////////
    // User paths.

    // Database home.
    char *get_home() const;
    void set_home(char *);

    // Database log file directory.
    char *get_log_dir() const;
    void set_log_dir(char *);

    // Database tmp file directory.
    char *get_tmp_dir() const;
    void set_tmp_dir(char *);

    // Database data file directories.
    char **get_data_dir() const;
    void set_data_dir(char **);

    // Database data file slots.
    int get_data_cnt() const;
    void set_data_cnt(int);

    // Next Database data file slot.
    int get_data_next() const;
    void set_data_next(int);


    ////////////////////////////////////////////////////////////////
    // Locking.

    // Return from lock_open().
    DbLockTab *get_lk_info() const;

    // Two dimensional conflict matrix.
    u_int8_t *get_lk_conflicts() const;
    void set_lk_conflicts(u_int8_t *);

    // Number of lock modes in table.
    int get_lk_modes() const;
    void set_lk_modes(int);

    // Maximum number of locks.
    unsigned int get_lk_max() const;
    void set_lk_max(unsigned int);

    // Deadlock detect on every conflict.
    u_int32_t get_lk_detect() const;
    void set_lk_detect(u_int32_t);

    // Yield function for threads.
    typedef int (*db_yield_fcn) (void);
    db_yield_fcn get_yield() const;
    void set_yield(db_yield_fcn);


    ////////////////////////////////////////////////////////////////
    // Logging.

    // Return from log_open().
    DbLog *get_lg_info() const;

    // Maximum file size.
    u_int32_t get_lg_max() const;
    void set_lg_max(u_int32_t);


    ////////////////////////////////////////////////////////////////
    // Memory pool.

    // Return from memp_open().
    DbMpool *get_mp_info() const;

    // Maximum file size for mmap.
    size_t get_mp_mmapsize() const;
    void set_mp_mmapsize(size_t);

    // Bytes in the mpool cache.
    size_t get_mp_size() const;
    void set_mp_size(size_t);


    ////////////////////////////////////////////////////////////////
    // Transactions.

    // Return from txn_open().
    DbTxnMgr *get_tx_info() const;

    // Maximum number of transactions.
    unsigned int get_tx_max() const;
    void set_tx_max(unsigned int);

    // Dispatch function for recovery.
    typedef int (*tx_recover_fcn)(DB_LOG *, DBT *, DB_LSN *, int, void *);
    tx_recover_fcn get_tx_recover() const;
    void set_tx_recover(tx_recover_fcn);

    // Flags.
    u_int32_t get_flags() const;
    void set_flags(u_int32_t);

    ////////////////////////////////////////////////////////////////
    // The default error model is to throw an exception whenever
    // an error occurs.  This generally allows for cleaner logic
    // for transaction processing, as a try block can surround a
    // single transaction.  Alternatively, since almost every method
    // returns an error code (errno), the error model can be set to
    // not throw exceptions, and instead return the appropriate code.
    //
    enum ErrorModel { Exception, ErrorReturn };
    void set_error_model(ErrorModel);
    ErrorModel get_error_model() const;

    // If an error is detected and the error call function
    // or stream is set, a message is dispatched or printed.
    // If a prefix is set, each message is prefixed.
    //
    // You can use set_errcall() or set_errfile() above to control
    // error functionality using a C model.  Alternatively, you can
    // call set_error_stream() to force all errors to a C++ stream.
    // It is unwise to mix these approaches.
    //
    class ostream* get_error_stream() const;
    void set_error_stream(class ostream*);

    // used internally
    static int runtime_error(const char *caller, int err, int in_destructor = 0);

private:
    // We can add data to this class if needed
    // since parent class is not allocated by db.
    // (see comment at top)

    // no copying
    DbEnv(const DbEnv &);
    operator = (const DbEnv &);

    ErrorModel error_model_;
    static void stream_error_function(const char *, char *);
    static ostream *error_stream_;
};

////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////
//
// Table access classes
//

//
// Represents a database table = a set of keys with associated values.
//
class _exported Db
{
    friend DbEnv;

public:
    int close(int flags);
    int cursor(DbTxn *txnid, Dbc **cursorp);
    int del(Dbt *key, DbTxn *txnid);
    int fd(int *fdp);
    int get(DbTxn *txnid, Dbt *key, Dbt *data, int flags);
    int put(DbTxn *txnid, Dbt *key, Dbt *data, int flags);
    int stat(void *sp, void *(*db_malloc)(size_t), int flags);
    int sync(int flags);

    DBTYPE get_type() const;

    static int open(const char *fname, DBTYPE type, int flags,
                    int mode, DbEnv *dbenv, DbInfo *info, Db **dbpp);

private:
    // We can add data to this class if needed
    // since it is implemented via a pointer.
    // (see comment at top)

    // Note: use Db::open() to get initialize pointers to a Db,
    // and call Db::close() rather than delete to release them.
    Db();
    ~Db();

    // no copying
    Db(const Db &);
    Db &operator = (const Db &);

    DEFINE_DB_CLASS(Db);
};

//
// A chunk of data, maybe a key or value.
//
class _exported Dbt : private DBT
{
    friend Dbc;
    friend Db;
    friend DbLog;
    friend DbMpoolFile;
    friend DbLockTab;

public:

    // key/data
    void *get_data() const;
    void set_data(void *);

    // key/data length
    u_int32_t get_size() const;
    void set_size(u_int32_t);

    // RO: length of user buffer.
    u_int32_t get_ulen() const;
    void set_ulen(u_int32_t);

    // RO: get/put record length.
    u_int32_t get_dlen() const;
    void set_dlen(u_int32_t);

    // RO: get/put record offset.
    u_int32_t get_doff() const;
    void set_doff(u_int32_t);

    // flags
    u_int32_t get_flags() const;
    void set_flags(u_int32_t);

    Dbt(void *data, size_t size);
    Dbt();
    ~Dbt();
    Dbt(const Dbt &);
    Dbt &operator = (const Dbt &);

private:
    // We can add data to this class if needed
    // since parent class is not allocated by db.
    // (see comment at top)
};

class _exported Dbc : protected DBC
{
    friend Db;

public:
    int close();
    int del(int flags);
    int get(Dbt* key, Dbt *data, int flags);
    int put(Dbt* key, Dbt *data, int flags);

private:
    // No data is permitted in this class (see comment at top)

    // Note: use Db::cursor() to get pointers to a Dbc,
    // and call Dbc::close() rather than delete to release them.
    //
    Dbc();
    ~Dbc();

    // no copying
    Dbc(const Dbc &);
    Dbc &operator = (const Dbc &);
};

#endif /* !_DB_CXX_H_ */