mdb.c 261 KB
Newer Older
1
/** @file mdb.c
Howard Chu's avatar
Howard Chu committed
2
 *	@brief Lightning memory-mapped database library
3
4
5
6
 *
 *	A Btree-based database management library modeled loosely on the
 *	BerkeleyDB API, but much simplified.
 */
Howard Chu's avatar
Howard Chu committed
7
/*
Howard Chu's avatar
Howard Chu committed
8
 * Copyright 2011-2014 Howard Chu, Symas Corp.
Howard Chu's avatar
Howard Chu committed
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
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 *
 * This code is derived from btree.c written by Martin Hedenfalk.
 *
 * Copyright (c) 2009, 2010 Martin Hedenfalk <martin@bzero.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
35
#ifndef _GNU_SOURCE
Hallvard Furuseth's avatar
Hallvard Furuseth committed
36
#define _GNU_SOURCE 1
37
#endif
Howard Chu's avatar
Howard Chu committed
38
#ifdef _WIN32
Howard Chu's avatar
Howard Chu committed
39
#include <malloc.h>
Howard Chu's avatar
Howard Chu committed
40
#include <windows.h>
Howard Chu's avatar
Howard Chu committed
41
42
43
44
45
/** getpid() returns int; MinGW defines pid_t but MinGW64 typedefs it
 *  as int64 which is wrong. MSVC doesn't define it at all, so just
 *  don't use it.
 */
#define MDB_PID_T	int
Howard Chu's avatar
Howard Chu committed
46
47
48
#define MDB_THR_T	DWORD
#include <sys/types.h>
#include <sys/stat.h>
Howard Chu's avatar
Howard Chu committed
49
50
#ifdef __GNUC__
# include <sys/param.h>
Howard Chu's avatar
Howard Chu committed
51
#else
Howard Chu's avatar
Howard Chu committed
52
53
54
55
56
57
58
59
# define LITTLE_ENDIAN	1234
# define BIG_ENDIAN	4321
# define BYTE_ORDER	LITTLE_ENDIAN
# ifndef SSIZE_MAX
#  define SSIZE_MAX	INT_MAX
# endif
#endif
#else
Howard Chu's avatar
Howard Chu committed
60
61
#include <sys/types.h>
#include <sys/stat.h>
Howard Chu's avatar
Howard Chu committed
62
#define MDB_PID_T	pid_t
Howard Chu's avatar
Howard Chu committed
63
#define MDB_THR_T	pthread_t
Howard Chu's avatar
Howard Chu committed
64
#include <sys/param.h>
Howard Chu's avatar
Howard Chu committed
65
66
67
68
69
#include <sys/uio.h>
#include <sys/mman.h>
#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
Howard Chu's avatar
Howard Chu committed
70
#include <fcntl.h>
Howard Chu's avatar
Howard Chu committed
71
#endif
Howard Chu's avatar
Howard Chu committed
72

Howard Chu's avatar
Howard Chu committed
73
74
75
76
77
78
79
80
81
#if defined(__mips) && defined(__linux)
/* MIPS has cache coherency issues, requires explicit cache control */
#include <asm/cachectl.h>
extern int cacheflush(char *addr, int nbytes, int cache);
#define CACHEFLUSH(addr, bytes, cache)	cacheflush(addr, bytes, cache)
#else
#define CACHEFLUSH(addr, bytes, cache)
#endif

82
83
#if defined(__linux) && !defined(MDB_FDATASYNC_WORKS)
/** fdatasync is broken on ext3/ext4fs on older kernels, see
Howard Chu's avatar
Howard Chu committed
84
85
86
 *	description in #mdb_env_open2 comments. You can safely
 *	define MDB_FDATASYNC_WORKS if this code will only be run
 *	on kernels 3.6 and newer.
87
88
89
 */
#define	BROKEN_FDATASYNC
#endif
90

Howard Chu's avatar
Howard Chu committed
91
#include <errno.h>
92
#include <limits.h>
Howard Chu's avatar
Howard Chu committed
93
#include <stddef.h>
94
#include <inttypes.h>
Howard Chu's avatar
Howard Chu committed
95
96
97
98
99
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
100

Howard Chu's avatar
Howard Chu committed
101
#if defined(__sun) || defined(ANDROID)
102
103
104
105
106
/* Most platforms have posix_memalign, older may only have memalign */
#define HAVE_MEMALIGN	1
#include <malloc.h>
#endif

107
#if !(defined(BYTE_ORDER) || defined(__BYTE_ORDER))
108
#include <netinet/in.h>
109
110
111
#include <resolv.h>	/* defines BYTE_ORDER on HPUX and Solaris */
#endif

112
#if defined(__APPLE__) || defined (BSD)
113
# define MDB_USE_SYSV_SEM	1
114
115
116
# define MDB_FDATASYNC		fsync
#elif defined(ANDROID)
# define MDB_FDATASYNC		fsync
117
118
#endif

119
120
#ifndef _WIN32
#include <pthread.h>
121
122
123
124
125
126
127
128
129
130
131
132
#ifdef MDB_USE_SYSV_SEM
#include <sys/ipc.h>
#include <sys/sem.h>
#ifdef _SEM_SEMUN_UNDEFINED
union semun {
	int val;
	struct semid_ds *buf;
	unsigned short *array;
};
#endif /* _SEM_SEMUN_UNDEFINED */
#endif /* MDB_USE_SYSV_SEM */
#endif /* !_WIN32 */
Howard Chu's avatar
Howard Chu committed
133

134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
#ifdef USE_VALGRIND
#include <valgrind/memcheck.h>
#define VGMEMP_CREATE(h,r,z)    VALGRIND_CREATE_MEMPOOL(h,r,z)
#define VGMEMP_ALLOC(h,a,s) VALGRIND_MEMPOOL_ALLOC(h,a,s)
#define VGMEMP_FREE(h,a) VALGRIND_MEMPOOL_FREE(h,a)
#define VGMEMP_DESTROY(h)	VALGRIND_DESTROY_MEMPOOL(h)
#define VGMEMP_DEFINED(a,s)	VALGRIND_MAKE_MEM_DEFINED(a,s)
#else
#define VGMEMP_CREATE(h,r,z)
#define VGMEMP_ALLOC(h,a,s)
#define VGMEMP_FREE(h,a)
#define VGMEMP_DESTROY(h)
#define VGMEMP_DEFINED(a,s)
#endif

Howard Chu's avatar
Howard Chu committed
149
#ifndef BYTE_ORDER
Howard Chu's avatar
Howard Chu committed
150
151
152
153
154
155
156
157
158
159
160
161
# if (defined(_LITTLE_ENDIAN) || defined(_BIG_ENDIAN)) && !(defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN))
/* Solaris just defines one or the other */
#  define LITTLE_ENDIAN	1234
#  define BIG_ENDIAN	4321
#  ifdef _LITTLE_ENDIAN
#   define BYTE_ORDER  LITTLE_ENDIAN
#  else
#   define BYTE_ORDER  BIG_ENDIAN
#  endif
# else
#  define BYTE_ORDER   __BYTE_ORDER
# endif
Howard Chu's avatar
Howard Chu committed
162
#endif
Howard Chu's avatar
Howard Chu committed
163

Howard Chu's avatar
Howard Chu committed
164
165
166
167
168
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN	__LITTLE_ENDIAN
#endif
#ifndef BIG_ENDIAN
#define BIG_ENDIAN	__BIG_ENDIAN
169
170
#endif

Howard Chu's avatar
Howard Chu committed
171
#if defined(__i386) || defined(__x86_64) || defined(_M_IX86)
Howard Chu's avatar
Howard Chu committed
172
173
174
#define MISALIGNED_OK	1
#endif

Howard Chu's avatar
Howard Chu committed
175
#include "lmdb.h"
176
177
#include "midl.h"

Howard Chu's avatar
Howard Chu committed
178
179
#if (BYTE_ORDER == LITTLE_ENDIAN) == (BYTE_ORDER == BIG_ENDIAN)
# error "Unknown or unsupported endianness (BYTE_ORDER)"
180
181
182
183
#elif (-6 & 5) || CHAR_BIT != 8 || UINT_MAX < 0xffffffff || ULONG_MAX % 0xFFFF
# error "Two's complement, reasonably sized integer types, please"
#endif

184
185
#ifdef __GNUC__
/** Put infrequently used env functions in separate section */
Howard Chu's avatar
Howard Chu committed
186
187
188
189
190
# ifdef __APPLE__
#  define	ESECT	__attribute__ ((section("__TEXT,text_env")))
# else
#  define	ESECT	__attribute__ ((section("text_env")))
# endif
191
192
193
194
#else
#define ESECT
#endif

Howard Chu's avatar
Howard Chu committed
195
/** @defgroup internal	LMDB Internals
196
197
 *	@{
 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
198
/** @defgroup compat	Compatibility Macros
Howard Chu's avatar
Howard Chu committed
199
200
201
202
 *	A bunch of macros to minimize the amount of platform-specific ifdefs
 *	needed throughout the rest of the code. When the features this library
 *	needs are similar enough to POSIX to be hidden in a one-or-two line
 *	replacement, this macro approach is used.
203
204
 *	@{
 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
205

Hallvard Furuseth's avatar
Hallvard Furuseth committed
206
	/** Features under development */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
207
208
#ifndef MDB_DEVEL
#define MDB_DEVEL 0
Hallvard Furuseth's avatar
Hallvard Furuseth committed
209
210
#endif

Hallvard Furuseth's avatar
Hallvard Furuseth committed
211
#if defined(_WIN32) || (defined(EOWNERDEAD) && !defined(MDB_USE_SYSV_SEM))
Hallvard Furuseth's avatar
Hallvard Furuseth committed
212
#define MDB_ROBUST_SUPPORTED	1
Hallvard Furuseth's avatar
Hallvard Furuseth committed
213
214
#endif

Hallvard Furuseth's avatar
Hallvard Furuseth committed
215
216
217
218
219
220
221
222
223
224
	/** Wrapper around __func__, which is a C99 feature */
#if __STDC_VERSION__ >= 199901L
# define mdb_func_	__func__
#elif __GNUC__ >= 2 || _MSC_VER >= 1300
# define mdb_func_	__FUNCTION__
#else
/* If a debug message says <mdb_unknown>(), update the #if statements above */
# define mdb_func_	"<mdb_unknown>"
#endif

Howard Chu's avatar
Howard Chu committed
225
#ifdef _WIN32
Howard Chu's avatar
Howard Chu committed
226
#define MDB_USE_HASH	1
227
#define MDB_PIDLOCK	0
Howard Chu's avatar
Howard Chu committed
228
229
#define THREAD_RET	DWORD
#define pthread_t	HANDLE
Howard Chu's avatar
Howard Chu committed
230
#define pthread_mutex_t	HANDLE
Howard Chu's avatar
Howard Chu committed
231
#define pthread_cond_t	HANDLE
Hallvard Furuseth's avatar
Hallvard Furuseth committed
232
typedef HANDLE mdb_mutex_t;
Howard Chu's avatar
Howard Chu committed
233
234
#define pthread_key_t	DWORD
#define pthread_self()	GetCurrentThreadId()
235
236
#define pthread_key_create(x,y)	\
	((*(x) = TlsAlloc()) == TLS_OUT_OF_INDEXES ? ErrCode() : 0)
Howard Chu's avatar
Howard Chu committed
237
238
#define pthread_key_delete(x)	TlsFree(x)
#define pthread_getspecific(x)	TlsGetValue(x)
239
#define pthread_setspecific(x,y)	(TlsSetValue(x,y) ? 0 : ErrCode())
Hallvard Furuseth's avatar
Hallvard Furuseth committed
240
#define pthread_mutex_consistent(mutex) 0
Howard Chu's avatar
Howard Chu committed
241
242
#define pthread_mutex_unlock(x)	ReleaseMutex(*x)
#define pthread_mutex_lock(x)	WaitForSingleObject(*x, INFINITE)
Howard Chu's avatar
Howard Chu committed
243
#define pthread_cond_signal(x)	SetEvent(*x)
Howard Chu's avatar
Howard Chu committed
244
#define pthread_cond_wait(cond,mutex)	do{SignalObjectAndWait(*mutex, *cond, INFINITE, FALSE); WaitForSingleObject(*mutex, INFINITE);}while(0)
Howard Chu's avatar
Howard Chu committed
245
246
#define THREAD_CREATE(thr,start,arg)	thr=CreateThread(NULL,0,start,arg,0,NULL)
#define THREAD_FINISH(thr)	WaitForSingleObject(thr, INFINITE)
Hallvard Furuseth's avatar
Hallvard Furuseth committed
247
248
249
#define MDB_MUTEX(env, rw)		((env)->me_##rw##mutex)
#define LOCK_MUTEX0(mutex)		WaitForSingleObject(mutex, INFINITE)
#define UNLOCK_MUTEX(mutex)		ReleaseMutex(mutex)
Howard Chu's avatar
Howard Chu committed
250
#define getpid()	GetCurrentProcessId()
251
#define	MDB_FDATASYNC(fd)	(!FlushFileBuffers(fd))
252
#define	MDB_MSYNC(addr,len,flags)	(!FlushViewOfFile(addr,len))
Howard Chu's avatar
Howard Chu committed
253
#define	ErrCode()	GetLastError()
Hallvard Furuseth's avatar
Hallvard Furuseth committed
254
#define GET_PAGESIZE(x) {SYSTEM_INFO si; GetSystemInfo(&si); (x) = si.dwPageSize;}
255
#define	close(fd)	(CloseHandle(fd) ? 0 : -1)
Howard Chu's avatar
Howard Chu committed
256
#define	munmap(ptr,len)	UnmapViewOfFile(ptr)
Hallvard Furuseth's avatar
Hallvard Furuseth committed
257
#ifdef PROCESS_QUERY_LIMITED_INFORMATION
Hallvard Furuseth's avatar
Hallvard Furuseth committed
258
259
260
261
#define MDB_PROCESS_QUERY_LIMITED_INFORMATION PROCESS_QUERY_LIMITED_INFORMATION
#else
#define MDB_PROCESS_QUERY_LIMITED_INFORMATION 0x1000
#endif
262
#define	Z	"I"
Howard Chu's avatar
Howard Chu committed
263
#else
Howard Chu's avatar
Howard Chu committed
264
265
266
#define THREAD_RET	void *
#define THREAD_CREATE(thr,start,arg)	pthread_create(&thr,NULL,start,arg)
#define THREAD_FINISH(thr)	pthread_join(thr,NULL)
267
#define	Z	"z"			/**< printf format modifier for size_t */
268

269
270
271
	/** For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile */
#define MDB_PIDLOCK			1

272
#ifdef MDB_USE_SYSV_SEM
273

274
275
276
277
278
279
typedef struct mdb_mutex {
	int semid;
	int semnum;
} mdb_mutex_t;

#define MDB_MUTEX(env, rw)		(&(env)->me_##rw##mutex)
Hallvard Furuseth's avatar
Hallvard Furuseth committed
280
#define LOCK_MUTEX0(mutex)		mdb_sem_wait(mutex)
281
282
283
284
285
#define UNLOCK_MUTEX(mutex)		do { \
	struct sembuf sb = { 0, 1, SEM_UNDO }; \
	sb.sem_num = (mutex)->semnum; \
	semop((mutex)->semid, &sb, 1); \
} while(0)
286
287

static int
288
mdb_sem_wait(mdb_mutex_t *sem)
289
290
{
   int rc;
291
292
   struct sembuf sb = { 0, -1, SEM_UNDO };
   sb.sem_num = sem->semnum;
293
   while ((rc = semop(sem->semid, &sb, 1)) && (rc = errno) == EINTR) ;
294
295
296
   return rc;
}

Howard Chu's avatar
Howard Chu committed
297
#else
Hallvard Furuseth's avatar
Hallvard Furuseth committed
298
	/** Pointer/HANDLE type of shared mutex/semaphore.
Howard Chu's avatar
Howard Chu committed
299
	 */
300
typedef pthread_mutex_t mdb_mutex_t;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
301
	/** Mutex for the reader table (rw = r) or write transaction (rw = w).
Howard Chu's avatar
Howard Chu committed
302
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
303
304
305
#define MDB_MUTEX(env, rw)	(&(env)->me_txns->mti_##rw##mutex)
	/** Lock the reader or writer mutex.
	 *	Returns 0 or a code to give #mdb_mutex_failed(), as in #LOCK_MUTEX().
Howard Chu's avatar
Howard Chu committed
306
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
307
308
#define LOCK_MUTEX0(mutex)	pthread_mutex_lock(mutex)
	/** Unlock the reader or writer mutex.
Howard Chu's avatar
Howard Chu committed
309
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
310
#define UNLOCK_MUTEX(mutex)	pthread_mutex_unlock(mutex)
311
#endif	/* MDB_USE_SYSV_SEM */
Howard Chu's avatar
Howard Chu committed
312
313
314

	/** Get the error code for the last failed system function.
	 */
Howard Chu's avatar
Howard Chu committed
315
#define	ErrCode()	errno
Howard Chu's avatar
Howard Chu committed
316

317
318
319
320
321
322
	/** An abstraction for a file handle.
	 *	On POSIX systems file handles are small integers. On Windows
	 *	they're opaque pointers.
	 */
#define	HANDLE	int

Howard Chu's avatar
Howard Chu committed
323
324
325
326
	/**	A value for an invalid file handle.
	 *	Mainly used to initialize file variables and signify that they are
	 *	unused.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
327
#define INVALID_HANDLE_VALUE	(-1)
Howard Chu's avatar
Howard Chu committed
328
329
330
331
332

	/** Get the size of a memory page for the system.
	 *	This is the basic size that the platform's memory manager uses, and is
	 *	fundamental to the use of memory-mapped files.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
333
#define	GET_PAGESIZE(x)	((x) = sysconf(_SC_PAGE_SIZE))
Howard Chu's avatar
Howard Chu committed
334
#endif
Howard Chu's avatar
Howard Chu committed
335

336
#if defined(_WIN32)
Howard Chu's avatar
Howard Chu committed
337
#define MNAME_LEN	32
338
339
#elif defined(MDB_USE_SYSV_SEM)
#define MNAME_LEN	0
340
341
#else
#define MNAME_LEN	(sizeof(pthread_mutex_t))
Howard Chu's avatar
Howard Chu committed
342
343
#endif

344
/** @} */
Howard Chu's avatar
Howard Chu committed
345

Hallvard Furuseth's avatar
Hallvard Furuseth committed
346
347
348
349
350
351
352
#ifdef MDB_ROBUST_SUPPORTED
	/** Lock mutex, handle any error, set rc = result.
	 *	Return 0 on success, nonzero (not rc) on error.
	 */
#define LOCK_MUTEX(rc, env, mutex) \
	(((rc) = LOCK_MUTEX0(mutex)) && \
	 ((rc) = mdb_mutex_failed(env, mutex, rc)))
353
static int mdb_mutex_failed(MDB_env *env, mdb_mutex_t *mutex, int rc);
Hallvard Furuseth's avatar
Hallvard Furuseth committed
354
355
356
357
358
#else
#define LOCK_MUTEX(rc, env, mutex) ((rc) = LOCK_MUTEX0(mutex))
#define mdb_mutex_failed(env, mutex, rc) (rc)
#endif

359
#ifndef _WIN32
Howard Chu's avatar
Howard Chu committed
360
361
362
363
364
365
/**	A flag for opening a file and requesting synchronous data writes.
 *	This is only used when writing a meta page. It's not strictly needed;
 *	we could just do a normal write and then immediately perform a flush.
 *	But if this flag is available it saves us an extra system call.
 *
 *	@note If O_DSYNC is undefined but exists in /usr/include,
Hallvard Furuseth's avatar
Hallvard Furuseth committed
366
367
368
369
370
371
 * preferably set some compiler flag to get the definition.
 * Otherwise compile with the less efficient -DMDB_DSYNC=O_SYNC.
 */
#ifndef MDB_DSYNC
# define MDB_DSYNC	O_DSYNC
#endif
372
373
374
375
376
377
378
#endif

/** Function for flushing the data of a file. Define this to fsync
 *	if fdatasync() is not supported.
 */
#ifndef MDB_FDATASYNC
# define MDB_FDATASYNC	fdatasync
379
380
381
382
383
384
385
386
387
388
389
390
#endif

#ifndef MDB_MSYNC
# define MDB_MSYNC(addr,len,flags)	msync(addr,len,flags)
#endif

#ifndef MS_SYNC
#define	MS_SYNC	1
#endif

#ifndef MS_ASYNC
#define	MS_ASYNC	0
391
392
#endif

Howard Chu's avatar
Howard Chu committed
393
394
395
396
397
398
399
400
	/** A page number in the database.
	 *	Note that 64 bit page numbers are overkill, since pages themselves
	 *	already represent 12-13 bits of addressable memory, and the OS will
	 *	always limit applications to a maximum of 63 bits of address space.
	 *
	 *	@note In the #MDB_node structure, we only store 48 bits of this value,
	 *	which thus limits us to only 60 bits of addressable data.
	 */
401
typedef MDB_ID	pgno_t;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
402

403
404
405
	/** A transaction ID.
	 *	See struct MDB_txn.mt_txnid for details.
	 */
406
typedef MDB_ID	txnid_t;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
407

Howard Chu's avatar
Howard Chu committed
408
409
410
/** @defgroup debug	Debug Macros
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
411
#ifndef MDB_DEBUG
412
	/**	Enable debug output.  Needs variable argument macros (a C99 feature).
Howard Chu's avatar
Howard Chu committed
413
414
415
	 *	Set this to 1 for copious tracing. Set to 2 to add dumps of all IDLs
	 *	read from and written to the database (used for free space management).
	 */
Howard Chu's avatar
Howard Chu committed
416
#define MDB_DEBUG 0
417
#endif
Howard Chu's avatar
Howard Chu committed
418

419
#if MDB_DEBUG
420
static int mdb_debug;
421
static txnid_t mdb_debug_start;
422

423
424
425
426
427
	/**	Print a debug message with printf formatting.
	 *	Requires double parenthesis around 2 or more args.
	 */
# define DPRINTF(args) ((void) ((mdb_debug) && DPRINTF0 args))
# define DPRINTF0(fmt, ...) \
Hallvard Furuseth's avatar
Hallvard Furuseth committed
428
	fprintf(stderr, "%s:%d " fmt "\n", mdb_func_, __LINE__, __VA_ARGS__)
Howard Chu's avatar
Howard Chu committed
429
#else
430
# define DPRINTF(args)	((void) 0)
Howard Chu's avatar
Howard Chu committed
431
#endif
Howard Chu's avatar
Howard Chu committed
432
433
434
	/**	Print a debug string.
	 *	The string is printed literally, with no format processing.
	 */
435
#define DPUTS(arg)	DPRINTF(("%s", arg))
436
437
438
	/** Debuging output value of a cursor DBI: Negative in a sub-cursor. */
#define DDBI(mc) \
	(((mc)->mc_flags & C_SUB) ? -(int)(mc)->mc_dbi : (int)(mc)->mc_dbi)
Howard Chu's avatar
Howard Chu committed
439
/** @} */
Howard Chu's avatar
Howard Chu committed
440

441
442
	/**	@brief The maximum size of a database page.
	 *
Hallvard Furuseth's avatar
Hallvard Furuseth committed
443
444
	 *	It is 32k or 64k, since value-PAGEBASE must fit in
	 *	#MDB_page.%mp_upper.
445
446
447
448
	 *
	 *	LMDB will use database pages < OS pages if needed.
	 *	That causes more I/O in write transactions: The OS must
	 *	know (read) the whole page before writing a partial page.
Howard Chu's avatar
Howard Chu committed
449
450
451
452
453
454
455
456
	 *
	 *	Note that we don't currently support Huge pages. On Linux,
	 *	regular data files cannot use Huge pages, and in general
	 *	Huge pages aren't actually pageable. We rely on the OS
	 *	demand-pager to read our data and page it out when memory
	 *	pressure from other processes is high. So until OSs have
	 *	actual paging support for Huge pages, they're not viable.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
457
#define MAX_PAGESIZE	 (PAGEBASE ? 0x10000 : 0x8000)
Howard Chu's avatar
Howard Chu committed
458
459
460
461
462
463
464
465
466
467
468
469
470

	/** The minimum number of keys required in a database page.
	 *	Setting this to a larger value will place a smaller bound on the
	 *	maximum size of a data item. Data items larger than this size will
	 *	be pushed into overflow pages instead of being stored directly in
	 *	the B-tree node. This value used to default to 4. With a page size
	 *	of 4096 bytes that meant that any item larger than 1024 bytes would
	 *	go into an overflow page. That also meant that on average 2-3KB of
	 *	each overflow page was wasted space. The value cannot be lower than
	 *	2 because then there would no longer be a tree structure. With this
	 *	value, items larger than 2KB will go into overflow pages, and on
	 *	average only 1KB will be wasted.
	 */
Howard Chu's avatar
Howard Chu committed
471
#define MDB_MINKEYS	 2
Howard Chu's avatar
Howard Chu committed
472

Howard Chu's avatar
Howard Chu committed
473
	/**	A stamp that identifies a file as an LMDB file.
Howard Chu's avatar
Howard Chu committed
474
475
476
	 *	There's nothing special about this value other than that it is easily
	 *	recognizable, and it will reflect any byte order mismatches.
	 */
Howard Chu's avatar
Howard Chu committed
477
#define MDB_MAGIC	 0xBEEFC0DE
Howard Chu's avatar
Howard Chu committed
478

479
	/**	The version number for a database's datafile format. */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
480
#define MDB_DATA_VERSION	 ((MDB_DEVEL) ? 999 : 1)
481
	/**	The version number for a database's lockfile format. */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
482
#define MDB_LOCK_VERSION	 ((MDB_DEVEL) ? 999 : 1)
Howard Chu's avatar
Howard Chu committed
483

484
	/**	@brief The max size of a key we can write, or 0 for dynamic max.
485
	 *
486
487
488
	 *	Define this as 0 to compute the max from the page size.  511
	 *	is default for backwards compat: liblmdb <= 0.9.10 can break
	 *	when modifying a DB with keys/dupsort data bigger than its max.
489
	 *	#MDB_DEVEL sets the default to 0.
490
	 *
491
492
493
	 *	Data items in an #MDB_DUPSORT database are also limited to
	 *	this size, since they're actually keys of a sub-DB.  Keys and
	 *	#MDB_DUPSORT data items must fit on a node in a regular page.
Howard Chu's avatar
Howard Chu committed
494
	 */
495
#ifndef MDB_MAXKEYSIZE
496
#define MDB_MAXKEYSIZE	 ((MDB_DEVEL) ? 0 : 511)
497
498
499
500
501
502
503
#endif

	/**	The maximum size of a key we can write to the environment. */
#if MDB_MAXKEYSIZE
#define ENV_MAXKEY(env)	(MDB_MAXKEYSIZE)
#else
#define ENV_MAXKEY(env)	((env)->me_maxkey)
504
#endif
Howard Chu's avatar
Howard Chu committed
505

506
507
508
509
510
511
	/**	@brief The maximum size of a data item.
	 *
	 *	We only store a 32 bit value for node sizes.
	 */
#define MAXDATASIZE	0xffffffffUL

Howard Chu's avatar
Howard Chu committed
512
#if MDB_DEBUG
513
514
515
516
	/**	Key size which fits in a #DKBUF.
	 *	@ingroup debug
	 */
#define DKBUF_MAXKEYSIZE ((MDB_MAXKEYSIZE) > 0 ? (MDB_MAXKEYSIZE) : 511)
Howard Chu's avatar
Howard Chu committed
517
518
519
520
	/**	A key buffer.
	 *	@ingroup debug
	 *	This is used for printing a hex dump of a key's contents.
	 */
521
#define DKBUF	char kbuf[DKBUF_MAXKEYSIZE*2+1]
Howard Chu's avatar
Howard Chu committed
522
523
524
525
	/**	Display a key in hex.
	 *	@ingroup debug
	 *	Invoke a function to display a key in hex.
	 */
Howard Chu's avatar
Howard Chu committed
526
527
#define	DKEY(x)	mdb_dkey(x, kbuf)
#else
Howard Chu's avatar
Howard Chu committed
528
#define	DKBUF
Howard Chu's avatar
Howard Chu committed
529
#define DKEY(x)	0
Howard Chu's avatar
Howard Chu committed
530
#endif
Howard Chu's avatar
Howard Chu committed
531

Howard Chu's avatar
Howard Chu committed
532
533
534
	/** An invalid page number.
	 *	Mainly used to denote an empty tree.
	 */
535
#define P_INVALID	 (~(pgno_t)0)
Howard Chu's avatar
Howard Chu committed
536

537
	/** Test if the flags \b f are set in a flag word \b w. */
Howard Chu's avatar
Howard Chu committed
538
539
#define F_ISSET(w, f)	 (((w) & (f)) == (f))

540
541
542
	/** Round \b n up to an even number. */
#define EVEN(n)		(((n) + 1U) & -2) /* sign-extending -2 to match n+1U */

Howard Chu's avatar
Howard Chu committed
543
544
545
546
	/**	Used for offsets within a single page.
	 *	Since memory pages are typically 4 or 8KB in size, 12-13 bits,
	 *	this is plenty.
	 */
Howard Chu's avatar
Howard Chu committed
547
548
typedef uint16_t	 indx_t;

Howard Chu's avatar
Howard Chu committed
549
550
551
552
	/**	Default size of memory map.
	 *	This is certainly too small for any actual applications. Apps should always set
	 *	the size explicitly using #mdb_env_set_mapsize().
	 */
Howard Chu's avatar
Howard Chu committed
553
554
#define DEFAULT_MAPSIZE	1048576

Howard Chu's avatar
Howard Chu committed
555
556
557
558
559
560
561
/**	@defgroup readers	Reader Lock Table
 *	Readers don't acquire any locks for their data access. Instead, they
 *	simply record their transaction ID in the reader table. The reader
 *	mutex is needed just to find an empty slot in the reader table. The
 *	slot's address is saved in thread-specific data so that subsequent read
 *	transactions started by the same thread need no further locking to proceed.
 *
Howard Chu's avatar
Howard Chu committed
562
563
 *	If #MDB_NOTLS is set, the slot address is not saved in thread-specific data.
 *
Howard Chu's avatar
Howard Chu committed
564
565
 *	No reader table is used if the database is on a read-only filesystem, or
 *	if #MDB_NOLOCK is set.
566
 *
Howard Chu's avatar
Howard Chu committed
567
568
569
 *	Since the database uses multi-version concurrency control, readers don't
 *	actually need any locking. This table is used to keep track of which
 *	readers are using data from which old transactions, so that we'll know
570
571
 *	when a particular old transaction is no longer in use. Old transactions
 *	that have discarded any data pages can then have those pages reclaimed
Howard Chu's avatar
Howard Chu committed
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
 *	for use by a later write transaction.
 *
 *	The lock table is constructed such that reader slots are aligned with the
 *	processor's cache line size. Any slot is only ever used by one thread.
 *	This alignment guarantees that there will be no contention or cache
 *	thrashing as threads update their own slot info, and also eliminates
 *	any need for locking when accessing a slot.
 *
 *	A writer thread will scan every slot in the table to determine the oldest
 *	outstanding reader transaction. Any freed pages older than this will be
 *	reclaimed by the writer. The writer doesn't use any locks when scanning
 *	this table. This means that there's no guarantee that the writer will
 *	see the most up-to-date reader info, but that's not required for correct
 *	operation - all we need is to know the upper bound on the oldest reader,
 *	we don't care at all about the newest reader. So the only consequence of
 *	reading stale information here is that old pages might hang around a
 *	while longer before being reclaimed. That's actually good anyway, because
 *	the longer we delay reclaiming old pages, the more likely it is that a
 *	string of contiguous pages can be found after coalescing old pages from
 *	many old transactions together.
 *	@{
 */
	/**	Number of slots in the reader table.
	 *	This value was chosen somewhat arbitrarily. 126 readers plus a
	 *	couple mutexes fit exactly into 8KB on my development machine.
	 *	Applications should set the table size using #mdb_env_set_maxreaders().
	 */
#define DEFAULT_READERS	126

	/**	The size of a CPU cache line in bytes. We want our lock structures
	 *	aligned to this size to avoid false cache line sharing in the
	 *	lock table.
	 *	This value works for most CPUs. For Itanium this should be 128.
	 */
Howard Chu's avatar
Howard Chu committed
606
#ifndef CACHELINE
Howard Chu's avatar
Howard Chu committed
607
#define CACHELINE	64
Howard Chu's avatar
Howard Chu committed
608
609
#endif

Howard Chu's avatar
Howard Chu committed
610
611
612
613
614
615
616
617
	/**	The information we store in a single slot of the reader table.
	 *	In addition to a transaction ID, we also record the process and
	 *	thread ID that owns a slot, so that we can detect stale information,
	 *	e.g. threads or processes that went away without cleaning up.
	 *	@note We currently don't check for stale records. We simply re-init
	 *	the table when we know that we're the only process opening the
	 *	lock file.
	 */
Howard Chu's avatar
Howard Chu committed
618
typedef struct MDB_rxbody {
619
	/**	Current Transaction ID when this transaction began, or (txnid_t)-1.
Howard Chu's avatar
Howard Chu committed
620
621
622
623
624
625
	 *	Multiple readers that start at the same time will probably have the
	 *	same ID here. Again, it's not important to exclude them from
	 *	anything; all we need to know is which version of the DB they
	 *	started from so we can avoid overwriting any data used in that
	 *	particular version.
	 */
626
	volatile txnid_t		mrb_txnid;
Howard Chu's avatar
Howard Chu committed
627
	/** The process ID of the process owning this reader txn. */
628
	volatile MDB_PID_T	mrb_pid;
Howard Chu's avatar
Howard Chu committed
629
	/** The thread ID of the thread owning this txn. */
630
	volatile MDB_THR_T	mrb_tid;
Howard Chu's avatar
Howard Chu committed
631
632
} MDB_rxbody;

Howard Chu's avatar
Howard Chu committed
633
	/** The actual reader record, with cacheline padding. */
Howard Chu's avatar
Howard Chu committed
634
typedef struct MDB_reader {
Howard Chu's avatar
Howard Chu committed
635
636
	union {
		MDB_rxbody mrx;
Howard Chu's avatar
Howard Chu committed
637
		/** shorthand for mrb_txnid */
Howard Chu's avatar
Howard Chu committed
638
639
640
#define	mr_txnid	mru.mrx.mrb_txnid
#define	mr_pid	mru.mrx.mrb_pid
#define	mr_tid	mru.mrx.mrb_tid
Howard Chu's avatar
Howard Chu committed
641
		/** cache line alignment */
Howard Chu's avatar
Howard Chu committed
642
643
		char pad[(sizeof(MDB_rxbody)+CACHELINE-1) & ~(CACHELINE-1)];
	} mru;
Howard Chu's avatar
Howard Chu committed
644
645
} MDB_reader;

Howard Chu's avatar
Howard Chu committed
646
647
648
649
650
651
652
	/** The header for the reader table.
	 *	The table resides in a memory-mapped file. (This is a different file
	 *	than is used for the main database.)
	 *
	 *	For POSIX the actual mutexes reside in the shared memory of this
	 *	mapped file. On Windows, mutexes are named objects allocated by the
	 *	kernel; we store the mutex names in this mapped file so that other
Howard Chu's avatar
Howard Chu committed
653
	 *	processes can grab them. This same approach is also used on
Howard Chu's avatar
Howard Chu committed
654
	 *	MacOSX/Darwin (using named semaphores) since MacOSX doesn't support
Howard Chu's avatar
Howard Chu committed
655
656
657
658
	 *	process-shared POSIX mutexes. For these cases where a named object
	 *	is used, the object name is derived from a 64 bit FNV hash of the
	 *	environment pathname. As such, naming collisions are extremely
	 *	unlikely. If a collision occurs, the results are unpredictable.
Howard Chu's avatar
Howard Chu committed
659
	 */
Howard Chu's avatar
Howard Chu committed
660
typedef struct MDB_txbody {
Howard Chu's avatar
Howard Chu committed
661
		/** Stamp identifying this as an LMDB file. It must be set
Howard Chu's avatar
Howard Chu committed
662
		 *	to #MDB_MAGIC. */
Howard Chu's avatar
Howard Chu committed
663
	uint32_t	mtb_magic;
664
665
		/** Format of this lock file. Must be set to #MDB_LOCK_FORMAT. */
	uint32_t	mtb_format;
666
#if defined(_WIN32)
Howard Chu's avatar
Howard Chu committed
667
	char	mtb_rmname[MNAME_LEN];
668
669
#elif defined(MDB_USE_SYSV_SEM)
	int 	mtb_semid;
Howard Chu's avatar
Howard Chu committed
670
#else
Howard Chu's avatar
Howard Chu committed
671
		/** Mutex protecting access to this table.
Hallvard Furuseth's avatar
Hallvard Furuseth committed
672
		 *	This is the #MDB_MUTEX(env,r) reader table lock.
Howard Chu's avatar
Howard Chu committed
673
		 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
674
	pthread_mutex_t	mtb_rmutex;
Howard Chu's avatar
Howard Chu committed
675
#endif
Howard Chu's avatar
Howard Chu committed
676
677
678
679
		/**	The ID of the last transaction committed to the database.
		 *	This is recorded here only for convenience; the value can always
		 *	be determined by reading the main database meta pages.
		 */
680
	volatile txnid_t		mtb_txnid;
Howard Chu's avatar
Howard Chu committed
681
682
683
684
		/** The number of slots that have been used in the reader table.
		 *	This always records the maximum count, it is not decremented
		 *	when readers release their slots.
		 */
685
	volatile unsigned	mtb_numreaders;
Howard Chu's avatar
Howard Chu committed
686
687
} MDB_txbody;

Howard Chu's avatar
Howard Chu committed
688
	/** The actual reader table definition. */
Howard Chu's avatar
Howard Chu committed
689
typedef struct MDB_txninfo {
Howard Chu's avatar
Howard Chu committed
690
691
692
	union {
		MDB_txbody mtb;
#define mti_magic	mt1.mtb.mtb_magic
693
#define mti_format	mt1.mtb.mtb_format
Hallvard Furuseth's avatar
Hallvard Furuseth committed
694
#define mti_rmutex	mt1.mtb.mtb_rmutex
Howard Chu's avatar
Howard Chu committed
695
#define mti_rmname	mt1.mtb.mtb_rmname
Howard Chu's avatar
Howard Chu committed
696
697
698
699
#define mti_txnid	mt1.mtb.mtb_txnid
#define mti_numreaders	mt1.mtb.mtb_numreaders
		char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
	} mt1;
700
701
702
#ifdef MDB_USE_SYSV_SEM
#define	mti_semid	mt1.mtb.mtb_semid
#else
Howard Chu's avatar
Howard Chu committed
703
	union {
704
#if defined(_WIN32)
Howard Chu's avatar
Howard Chu committed
705
		char mt2_wmname[MNAME_LEN];
Howard Chu's avatar
Howard Chu committed
706
707
#define	mti_wmname	mt2.mt2_wmname
#else
Howard Chu's avatar
Howard Chu committed
708
709
		pthread_mutex_t	mt2_wmutex;
#define mti_wmutex	mt2.mt2_wmutex
Howard Chu's avatar
Howard Chu committed
710
#endif
711
		char pad[(MNAME_LEN+CACHELINE-1) & ~(CACHELINE-1)];
Howard Chu's avatar
Howard Chu committed
712
	} mt2;
713
#endif
Howard Chu's avatar
Howard Chu committed
714
	MDB_reader	mti_readers[1];
Howard Chu's avatar
Howard Chu committed
715
} MDB_txninfo;
716
717
718
719
720
721

	/** Lockfile format signature: version, features and field layout */
#define MDB_LOCK_FORMAT \
	((uint32_t) \
	 ((MDB_LOCK_VERSION) \
	  /* Flags which describe functionality */ \
722
	  + (((MNAME_LEN) == 0)   << 18) /* MDB_USE_SYSV_SEM */ \
723
	  + (((MDB_PIDLOCK) != 0) << 16)))
Howard Chu's avatar
Howard Chu committed
724
/** @} */
Howard Chu's avatar
Howard Chu committed
725

Howard Chu's avatar
Howard Chu committed
726
/** Common header for all page types.
Howard Chu's avatar
Howard Chu committed
727
 * Overflow records occupy a number of contiguous pages with no
Howard Chu's avatar
Howard Chu committed
728
729
 * headers on any page after the first.
 */
Howard Chu's avatar
Howard Chu committed
730
typedef struct MDB_page {
731
732
#define	mp_pgno	mp_p.p_pgno
#define	mp_next	mp_p.p_next
Howard Chu's avatar
Howard Chu committed
733
	union {
734
		pgno_t		p_pgno;	/**< page number */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
735
		struct MDB_page *p_next; /**< for in-memory list of freed pages */
736
	} mp_p;
Howard Chu's avatar
Howard Chu committed
737
	uint16_t	mp_pad;
Howard Chu's avatar
Howard Chu committed
738
739
740
741
742
/**	@defgroup mdb_page	Page Flags
 *	@ingroup internal
 *	Flags for the page headers.
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
743
744
745
746
#define	P_BRANCH	 0x01		/**< branch page */
#define	P_LEAF		 0x02		/**< leaf page */
#define	P_OVERFLOW	 0x04		/**< overflow page */
#define	P_META		 0x08		/**< meta page */
747
#define	P_DIRTY		 0x10		/**< dirty page, also set for #P_SUBP pages */
Howard Chu's avatar
Howard Chu committed
748
#define	P_LEAF2		 0x20		/**< for #MDB_DUPFIXED records */
Howard Chu's avatar
Howard Chu committed
749
#define	P_SUBP		 0x40		/**< for #MDB_DUPSORT sub-pages */
Howard Chu's avatar
Howard Chu committed
750
#define	P_LOOSE		 0x4000		/**< page was dirtied then freed, can be reused */
Howard Chu's avatar
Howard Chu committed
751
#define	P_KEEP		 0x8000		/**< leave this page alone during spill */
Howard Chu's avatar
Howard Chu committed
752
/** @} */
Howard Chu's avatar
Howard Chu committed
753
	uint16_t	mp_flags;		/**< @ref mdb_page */
754
755
756
#define mp_lower	mp_pb.pb.pb_lower
#define mp_upper	mp_pb.pb.pb_upper
#define mp_pages	mp_pb.pb_pages
Howard Chu's avatar
Howard Chu committed
757
	union {
Howard Chu's avatar
Howard Chu committed
758
		struct {
759
760
761
762
763
			indx_t		pb_lower;		/**< lower bound of free space */
			indx_t		pb_upper;		/**< upper bound of free space */
		} pb;
		uint32_t	pb_pages;	/**< number of overflow pages */
	} mp_pb;
Howard Chu's avatar
Howard Chu committed
764
	indx_t		mp_ptrs[1];		/**< dynamic size */
Howard Chu's avatar
Howard Chu committed
765
766
} MDB_page;

Howard Chu's avatar
Howard Chu committed
767
	/** Size of the page header, excluding dynamic data at the end */
768
#define PAGEHDRSZ	 ((unsigned) offsetof(MDB_page, mp_ptrs))
Howard Chu's avatar
Howard Chu committed
769

Howard Chu's avatar
Howard Chu committed
770
771
772
	/** Address of first usable data byte in a page, after the header */
#define METADATA(p)	 ((void *)((char *)(p) + PAGEHDRSZ))

773
	/** ITS#7713, change PAGEBASE to handle 65536 byte pages */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
774
#define	PAGEBASE	((MDB_DEVEL) ? PAGEHDRSZ : 0)
775

Howard Chu's avatar
Howard Chu committed
776
	/** Number of nodes on a page */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
777
#define NUMKEYS(p)	 (((p)->mp_lower - (PAGEHDRSZ-PAGEBASE)) >> 1)
Howard Chu's avatar
Howard Chu committed
778
779

	/** The amount of space remaining in the page */
Howard Chu's avatar
Howard Chu committed
780
#define SIZELEFT(p)	 (indx_t)((p)->mp_upper - (p)->mp_lower)
Howard Chu's avatar
Howard Chu committed
781
782

	/** The percentage of space used in the page, in tenths of a percent. */
Howard Chu's avatar
Howard Chu committed
783
784
#define PAGEFILL(env, p) (1000L * ((env)->me_psize - PAGEHDRSZ - SIZELEFT(p)) / \
				((env)->me_psize - PAGEHDRSZ))
Howard Chu's avatar
Howard Chu committed
785
786
787
788
789
790
	/** The minimum page fill factor, in tenths of a percent.
	 *	Pages emptier than this are candidates for merging.
	 */
#define FILL_THRESHOLD	 250

	/** Test if a page is a leaf page */
Howard Chu's avatar
Howard Chu committed
791
#define IS_LEAF(p)	 F_ISSET((p)->mp_flags, P_LEAF)
Howard Chu's avatar
Howard Chu committed
792
	/** Test if a page is a LEAF2 page */
Howard Chu's avatar
Howard Chu committed
793
#define IS_LEAF2(p)	 F_ISSET((p)->mp_flags, P_LEAF2)
Howard Chu's avatar
Howard Chu committed
794
	/** Test if a page is a branch page */
Howard Chu's avatar
Howard Chu committed
795
#define IS_BRANCH(p)	 F_ISSET((p)->mp_flags, P_BRANCH)
Howard Chu's avatar
Howard Chu committed
796
	/** Test if a page is an overflow page */
Howard Chu's avatar
Howard Chu committed
797
#define IS_OVERFLOW(p)	 F_ISSET((p)->mp_flags, P_OVERFLOW)
Howard Chu's avatar
Howard Chu committed
798
799
	/** Test if a page is a sub page */
#define IS_SUBP(p)	 F_ISSET((p)->mp_flags, P_SUBP)
Howard Chu's avatar
Howard Chu committed
800

Howard Chu's avatar
Howard Chu committed
801
	/** The number of overflow pages needed to store the given size. */
802
#define OVPAGES(size, psize)	((PAGEHDRSZ-1 + (size)) / (psize) + 1)
Howard Chu's avatar
Howard Chu committed
803

804
	/** Link in #MDB_txn.%mt_loose_pgs list */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
805
#define NEXT_LOOSE_PAGE(p)		(*(MDB_page **)((p) + 2))
806

Howard Chu's avatar
Howard Chu committed
807
	/** Header for a single key/data pair within a page.
808
809
	 * Used in pages of type #P_BRANCH and #P_LEAF without #P_LEAF2.
	 * We guarantee 2-byte alignment for 'MDB_node's.
Howard Chu's avatar
Howard Chu committed
810
811
812
813
	 */
typedef struct MDB_node {
	/** lo and hi are used for data size on leaf nodes and for
	 * child pgno on branch nodes. On 64 bit platforms, flags
814
	 * is also used for pgno. (Branch nodes have no flags).
Howard Chu's avatar
Howard Chu committed
815
	 * They are in host byte order in case that lets some
816
	 * accesses be optimized into a 32-bit word access.
Howard Chu's avatar
Howard Chu committed
817
	 */
818
819
820
821
822
#if BYTE_ORDER == LITTLE_ENDIAN
	unsigned short	mn_lo, mn_hi;	/**< part of data size or pgno */
#else
	unsigned short	mn_hi, mn_lo;
#endif
Howard Chu's avatar
Howard Chu committed
823
824
825
826
827
/** @defgroup mdb_node Node Flags
 *	@ingroup internal
 *	Flags for node headers.
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
828
829
830
#define F_BIGDATA	 0x01			/**< data put on overflow page */
#define F_SUBDATA	 0x02			/**< data is a sub-database */
#define F_DUPDATA	 0x04			/**< data has duplicates */
Howard Chu's avatar
Howard Chu committed
831
832

/** valid flags for #mdb_node_add() */
833
#define	NODE_ADD_FLAGS	(F_DUPDATA|F_SUBDATA|MDB_RESERVE|MDB_APPEND)
Howard Chu's avatar
Howard Chu committed
834

Howard Chu's avatar
Howard Chu committed
835
836
/** @} */
	unsigned short	mn_flags;		/**< @ref mdb_node */
Howard Chu's avatar
Howard Chu committed
837
838
839
840
841
842
843
	unsigned short	mn_ksize;		/**< key size */
	char		mn_data[1];			/**< key and data are appended here */
} MDB_node;

	/** Size of the node header, excluding dynamic data at the end */
#define NODESIZE	 offsetof(MDB_node, mn_data)

844
845
846
	/** Bit position of top word in page number, for shifting mn_flags */
#define PGNO_TOPWORD ((pgno_t)-1 > 0xffffffffu ? 32 : 0)

Howard Chu's avatar
Howard Chu committed
847
	/** Size of a node in a branch page with a given key.
Howard Chu's avatar
Howard Chu committed
848
849
850
851
	 *	This is just the node header plus the key, there is no data.
	 */
#define INDXSIZE(k)	 (NODESIZE + ((k) == NULL ? 0 : (k)->mv_size))

Howard Chu's avatar
Howard Chu committed
852
	/** Size of a node in a leaf page with a given key and data.
Howard Chu's avatar
Howard Chu committed
853
854
855
856
	 *	This is node header plus key plus data size.
	 */
#define LEAFSIZE(k, d)	 (NODESIZE + (k)->mv_size + (d)->mv_size)

Howard Chu's avatar
Howard Chu committed
857
	/** Address of node \b i in page \b p */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
858
#define NODEPTR(p, i)	 ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i] + PAGEBASE))
Howard Chu's avatar
Howard Chu committed
859
860
861
862
863
864
865
866

	/** Address of the key for the node */
#define NODEKEY(node)	 (void *)((node)->mn_data)

	/** Address of the data for a node */
#define NODEDATA(node)	 (void *)((char *)(node)->mn_data + (node)->mn_ksize)

	/** Get the page number pointed to by a branch node */
867
868
869
#define NODEPGNO(node) \
	((node)->mn_lo | ((pgno_t) (node)->mn_hi << 16) | \
	 (PGNO_TOPWORD ? ((pgno_t) (node)->mn_flags << PGNO_TOPWORD) : 0))
Howard Chu's avatar
Howard Chu committed
870
871
872
	/** Set the page number in a branch node */
#define SETPGNO(node,pgno)	do { \
	(node)->mn_lo = (pgno) & 0xffff; (node)->mn_hi = (pgno) >> 16; \
873
	if (PGNO_TOPWORD) (node)->mn_flags = (pgno) >> PGNO_TOPWORD; } while(0)
Howard Chu's avatar
Howard Chu committed
874
875
876
877
878
879
880
881
882

	/** Get the size of the data in a leaf node */
#define NODEDSZ(node)	 ((node)->mn_lo | ((unsigned)(node)->mn_hi << 16))
	/** Set the size of the data for a leaf node */
#define SETDSZ(node,size)	do { \
	(node)->mn_lo = (size) & 0xffff; (node)->mn_hi = (size) >> 16;} while(0)
	/** The size of a key in a node */
#define NODEKSZ(node)	 ((node)->mn_ksize)

Howard Chu's avatar
Howard Chu committed
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
	/** Copy a page number from src to dst */
#ifdef MISALIGNED_OK
#define COPY_PGNO(dst,src)	dst = src
#else
#if SIZE_MAX > 4294967295UL
#define COPY_PGNO(dst,src)	do { \
	unsigned short *s, *d;	\
	s = (unsigned short *)&(src);	\
	d = (unsigned short *)&(dst);	\
	*d++ = *s++;	\
	*d++ = *s++;	\
	*d++ = *s++;	\
	*d = *s;	\
} while (0)
#else
#define COPY_PGNO(dst,src)	do { \
	unsigned short *s, *d;	\
	s = (unsigned short *)&(src);	\
	d = (unsigned short *)&(dst);	\
	*d++ = *s++;	\
	*d = *s;	\
} while (0)
#endif
#endif
Howard Chu's avatar
Howard Chu committed
907
908
909
910
911
912
	/** The address of a key in a LEAF2 page.
	 *	LEAF2 pages are used for #MDB_DUPFIXED sorted-duplicate sub-DBs.
	 *	There are no node headers, keys are stored contiguously.
	 */
#define LEAF2KEY(p, i, ks)	((char *)(p) + PAGEHDRSZ + ((i)*(ks)))

Howard Chu's avatar
Howard Chu committed
913
914
915
916
917
918
	/** Set the \b node's key into \b keyptr, if requested. */
#define MDB_GET_KEY(node, keyptr)	{ if ((keyptr) != NULL) { \
	(keyptr)->mv_size = NODEKSZ(node); (keyptr)->mv_data = NODEKEY(node); } }

	/** Set the \b node's key into \b key. */
#define MDB_GET_KEY2(node, key)	{ key.mv_size = NODEKSZ(node); key.mv_data = NODEKEY(node); }
Howard Chu's avatar
Howard Chu committed
919
920

	/** Information about a single database in the environment. */
Howard Chu's avatar
Howard Chu committed
921
typedef struct MDB_db {
Howard Chu's avatar
Howard Chu committed
922
	uint32_t	md_pad;		/**< also ksize for LEAF2 pages */
923
	uint16_t	md_flags;	/**< @ref mdb_dbi_open */
Howard Chu's avatar
Howard Chu committed
924
	uint16_t	md_depth;	/**< depth of this tree */
925
926
927
928
	pgno_t		md_branch_pages;	/**< number of internal pages */
	pgno_t		md_leaf_pages;		/**< number of leaf pages */
	pgno_t		md_overflow_pages;	/**< number of overflow pages */
	size_t		md_entries;		/**< number of data items */
Howard Chu's avatar
Howard Chu committed
929
	pgno_t		md_root;		/**< the root page of this tree */
Howard Chu's avatar
Howard Chu committed
930
931
} MDB_db;

932
	/** mdb_dbi_open flags */
933
934
#define MDB_VALID	0x8000		/**< DB handle is valid, for me_dbflags */
#define PERSISTENT_FLAGS	(0xffff & ~(MDB_VALID))
935
936
937
#define VALID_FLAGS	(MDB_REVERSEKEY|MDB_DUPSORT|MDB_INTEGERKEY|MDB_DUPFIXED|\
	MDB_INTEGERDUP|MDB_REVERSEDUP|MDB_CREATE)

Howard Chu's avatar
Howard Chu committed
938
	/** Handle for the DB used to track free pages. */
Howard Chu's avatar
Howard Chu committed
939
#define	FREE_DBI	0
Howard Chu's avatar
Howard Chu committed
940
	/** Handle for the default DB. */
Howard Chu's avatar
Howard Chu committed
941
942
#define	MAIN_DBI	1

943
944
945
946
	/** Meta page content.
	 *	A meta page is the start point for accessing a database snapshot.
	 *	Pages 0-1 are meta pages. Transaction N writes meta page #(N % 2).
	 */
Howard Chu's avatar
Howard Chu committed
947
typedef struct MDB_meta {
Howard Chu's avatar
Howard Chu committed
948
		/** Stamp identifying this as an LMDB file. It must be set
Howard Chu's avatar
Howard Chu committed
949
		 *	to #MDB_MAGIC. */
Howard Chu's avatar
Howard Chu committed
950
	uint32_t	mm_magic;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
951
		/** Version number of this file. Must be set to #MDB_DATA_VERSION. */
Howard Chu's avatar
Howard Chu committed
952
	uint32_t	mm_version;
Howard Chu's avatar
Howard Chu committed
953
954
955
956
	void		*mm_address;		/**< address for fixed mapping */
	size_t		mm_mapsize;			/**< size of mmap region */
	MDB_db		mm_dbs[2];			/**< first is free space, 2nd is main db */
	/** The size of pages used in this DB */
Howard Chu's avatar
Howard Chu committed
957
#define	mm_psize	mm_dbs[0].md_pad
Howard Chu's avatar
Howard Chu committed
958
	/** Any persistent environment flags. @ref mdb_env */
Howard Chu's avatar
Howard Chu committed
959
#define	mm_flags	mm_dbs[0].md_flags
Howard Chu's avatar
Howard Chu committed
960
	pgno_t		mm_last_pg;			/**< last used page in file */
961
	volatile txnid_t	mm_txnid;	/**< txnid that committed this page */
Howard Chu's avatar
Howard Chu committed
962
963
} MDB_meta;

964
	/** Buffer for a stack-allocated meta page.
965
966
967
968
	 *	The members define size and alignment, and silence type
	 *	aliasing warnings.  They are not used directly; that could
	 *	mean incorrectly using several union members in parallel.
	 */
969
typedef union MDB_metabuf {
970
971
972
973
974
	MDB_page	mb_page;
	struct {
		char		mm_pad[PAGEHDRSZ];
		MDB_meta	mm_meta;
	} mb_metabuf;
975
} MDB_metabuf;
976

Howard Chu's avatar
Howard Chu committed
977
978
979
980
981
982
983
984
985
	/** Auxiliary DB info.
	 *	The information here is mostly static/read-only. There is
	 *	only a single copy of this record in the environment.
	 */
typedef struct MDB_dbx {
	MDB_val		md_name;		/**< name of the database */
	MDB_cmp_func	*md_cmp;	/**< function for comparing keys */
	MDB_cmp_func	*md_dcmp;	/**< function for comparing data items */
	MDB_rel_func	*md_rel;	/**< user relocate function */
986
	void		*md_relctx;		/**< user-provided context for md_rel */
Howard Chu's avatar
Howard Chu committed
987
} MDB_dbx;
Howard Chu's avatar
Howard Chu committed
988

Howard Chu's avatar
Howard Chu committed
989
990
991
992
	/** A database transaction.
	 *	Every operation requires a transaction handle.
	 */
struct MDB_txn {
993
994
	MDB_txn		*mt_parent;		/**< parent of a nested txn */
	MDB_txn		*mt_child;		/**< nested txn under this txn */
Howard Chu's avatar
Howard Chu committed
995
996
997
998
999
	pgno_t		mt_next_pgno;	/**< next unallocated page */
	/** The ID of this transaction. IDs are integers incrementing from 1.
	 *	Only committed write transactions increment the ID. If a transaction
	 *	aborts, the ID may be re-used by the next writer.
	 */
1000
	txnid_t		mt_txnid;
Howard Chu's avatar
Howard Chu committed
1001
1002
1003
	MDB_env		*mt_env;		/**< the DB environment */
	/** The list of pages that became unused during this transaction.
	 */
1004
	MDB_IDL		mt_free_pgs;
Howard Chu's avatar
Howard Chu committed
1005
	/** The list of loose pages that became unused and may be reused
1006
	 *	in this transaction, linked through #NEXT_LOOSE_PAGE(page).
Howard Chu's avatar
Howard Chu committed
1007
1008
	 */
	MDB_page	*mt_loose_pgs;
1009
1010
	/* #Number of loose pages (#mt_loose_pgs) */
	int			mt_loose_count;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
1011
	/** The sorted list of dirty pages we temporarily wrote to disk
1012
1013
	 *	because the dirty list was full. page numbers in here are
	 *	shifted left by 1, deleted slots have the LSB set.
Howard Chu's avatar
Howard Chu committed
1014
1015
	 */
	MDB_IDL		mt_spill_pgs;
Howard Chu's avatar
Howard Chu committed
1016
	union {
Hallvard Furuseth's avatar
Hallvard Furuseth committed
1017
1018
1019
1020
		/** For write txns: Modified pages. Sorted when not MDB_WRITEMAP. */
		MDB_ID2L	dirty_list;
		/** For read txns: This thread/txn's reader table slot, or NULL. */
		MDB_reader	*reader;
Howard Chu's avatar
Howard Chu committed
1021
1022
1023
1024
1025
	} mt_u;
	/** Array of records for each DB known in the environment. */
	MDB_dbx		*mt_dbxs;
	/** Array of MDB_db records for each known DB */
	MDB_db		*mt_dbs;
1026
1027
	/** Array of sequence numbers for each DB handle */
	unsigned int	*mt_dbiseqs;
Howard Chu's avatar
Howard Chu committed
1028
1029
1030
1031
/** @defgroup mt_dbflag	Transaction DB Flags
 *	@ingroup internal
 * @{
 */
1032
#define DB_DIRTY	0x01		/**< DB was modified or is DUPSORT data */
1033
1034
#define DB_STALE	0x02		/**< Named-DB record is older than txnID */
#define DB_NEW		0x04		/**< Named-DB handle opened in this txn */
1035
#define DB_VALID	0x08		/**< DB handle is valid, see also #MDB_VALID */
Howard Chu's avatar
Howard Chu committed
1036
/** @} */
1037
	/** In write txns, array of cursors for each DB */
Howard Chu's avatar
Howard Chu committed
1038
	MDB_cursor	**mt_cursors;
Howard Chu's avatar
Howard Chu committed
1039
1040
	/** Array of flags for each DB */
	unsigned char	*mt_dbflags;
Howard Chu's avatar
Howard Chu committed
1041
1042
1043
	/**	Number of DB records in use. This number only ever increments;
	 *	we don't decrement it when individual DB handles are closed.
	 */
1044
	MDB_dbi		mt_numdbs;
Howard Chu's avatar
Howard Chu committed
1045

Howard Chu's avatar
Howard Chu committed
1046
1047
1048
1049
/** @defgroup mdb_txn	Transaction Flags
 *	@ingroup internal
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
1050
#define MDB_TXN_RDONLY		0x01		/**< read-only transaction */
1051
#define MDB_TXN_ERROR		0x02		/**< txn is unusable after an error */
1052
#define MDB_TXN_DIRTY		0x04		/**< must write, even if dirty list is empty */
Howard Chu's avatar
Howard Chu committed
1053
#define MDB_TXN_SPILLS		0x08		/**< txn or a parent has spilled pages */
Howard Chu's avatar
Howard Chu committed
1054
1055
/** @} */
	unsigned int	mt_flags;		/**< @ref mdb_txn */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
1056
	/** #dirty_list room: Array size - \#dirty pages visible to this txn.
1057
1058
1059
1060
	 *	Includes ancestor txns' dirty pages not hidden by other txns'
	 *	dirty/spilled pages. Thus commit(nested txn) has room to merge
	 *	dirty_list into mt_parent after freeing hidden mt_parent pages.
	 */
1061
	unsigned int	mt_dirty_room;
Howard Chu's avatar
Howard Chu committed
1062
};
Howard Chu's avatar
Howard Chu committed
1063

Howard Chu's avatar
Howard Chu committed
1064
/** Enough space for 2^32 nodes with minimum of 2 keys per node. I.e., plenty.
1065
1066
1067
 * At 4 keys per node, enough for 2^64 nodes, so there's probably no need to
 * raise this on a 64 bit machine.
 */
Howard Chu's avatar
Howard Chu committed
1068
#define CURSOR_STACK		 32
Howard Chu's avatar
Howard Chu committed
1069

Howard Chu's avatar
Howard Chu committed
1070
struct MDB_xcursor;