mdb.c 248 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
73

#include <errno.h>
74
#include <limits.h>
Howard Chu's avatar
Howard Chu committed
75
#include <stddef.h>
76
#include <inttypes.h>
Howard Chu's avatar
Howard Chu committed
77
78
79
80
81
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
82

83
#if !(defined(BYTE_ORDER) || defined(__BYTE_ORDER))
84
#include <netinet/in.h>
85
86
87
#include <resolv.h>	/* defines BYTE_ORDER on HPUX and Solaris */
#endif

88
#if defined(__APPLE__) || defined (BSD)
89
90
91
92
# define MDB_USE_POSIX_SEM	1
# define MDB_FDATASYNC		fsync
#elif defined(ANDROID)
# define MDB_FDATASYNC		fsync
93
94
#endif

95
96
#ifndef _WIN32
#include <pthread.h>
97
#ifdef MDB_USE_POSIX_SEM
98
# define MDB_USE_HASH		1
Howard Chu's avatar
Howard Chu committed
99
100
101
102
#include <semaphore.h>
#endif
#endif

103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
#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
118
#ifndef BYTE_ORDER
Howard Chu's avatar
Howard Chu committed
119
120
121
122
123
124
125
126
127
128
129
130
# 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
131
#endif
Howard Chu's avatar
Howard Chu committed
132

Howard Chu's avatar
Howard Chu committed
133
134
135
136
137
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN	__LITTLE_ENDIAN
#endif
#ifndef BIG_ENDIAN
#define BIG_ENDIAN	__BIG_ENDIAN
138
139
#endif

Howard Chu's avatar
Howard Chu committed
140
#if defined(__i386) || defined(__x86_64) || defined(_M_IX86)
Howard Chu's avatar
Howard Chu committed
141
142
143
#define MISALIGNED_OK	1
#endif

Howard Chu's avatar
Howard Chu committed
144
#include "lmdb.h"
145
146
#include "midl.h"

Howard Chu's avatar
Howard Chu committed
147
148
#if (BYTE_ORDER == LITTLE_ENDIAN) == (BYTE_ORDER == BIG_ENDIAN)
# error "Unknown or unsupported endianness (BYTE_ORDER)"
149
150
151
152
#elif (-6 & 5) || CHAR_BIT != 8 || UINT_MAX < 0xffffffff || ULONG_MAX % 0xFFFF
# error "Two's complement, reasonably sized integer types, please"
#endif

Howard Chu's avatar
Howard Chu committed
153
/** @defgroup internal	LMDB Internals
154
155
 *	@{
 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
156
/** @defgroup compat	Compatibility Macros
Howard Chu's avatar
Howard Chu committed
157
158
159
160
 *	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.
161
162
 *	@{
 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
163
164
165
166
167
168
169
170
171
172
173

	/** 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
174
#ifdef _WIN32
Howard Chu's avatar
Howard Chu committed
175
#define MDB_USE_HASH	1
176
#define MDB_PIDLOCK	0
Howard Chu's avatar
Howard Chu committed
177
178
#define THREAD_RET	DWORD
#define pthread_t	HANDLE
Howard Chu's avatar
Howard Chu committed
179
#define pthread_mutex_t	HANDLE
Howard Chu's avatar
Howard Chu committed
180
#define pthread_cond_t	HANDLE
Howard Chu's avatar
Howard Chu committed
181
182
#define pthread_key_t	DWORD
#define pthread_self()	GetCurrentThreadId()
183
184
#define pthread_key_create(x,y)	\
	((*(x) = TlsAlloc()) == TLS_OUT_OF_INDEXES ? ErrCode() : 0)
Howard Chu's avatar
Howard Chu committed
185
186
#define pthread_key_delete(x)	TlsFree(x)
#define pthread_getspecific(x)	TlsGetValue(x)
187
#define pthread_setspecific(x,y)	(TlsSetValue(x,y) ? 0 : ErrCode())
Howard Chu's avatar
Howard Chu committed
188
189
#define pthread_mutex_unlock(x)	ReleaseMutex(x)
#define pthread_mutex_lock(x)	WaitForSingleObject(x, INFINITE)
Howard Chu's avatar
Howard Chu committed
190
191
#define pthread_cond_signal(x)	SetEvent(*x)
#define pthread_cond_wait(cond,mutex)	SignalObjectAndWait(*mutex, *cond, INFINITE, FALSE); WaitForSingleObject(*mutex, INFINITE)
Howard Chu's avatar
Howard Chu committed
192
193
#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
194
195
196
197
#define LOCK_MUTEX_R(env)	pthread_mutex_lock((env)->me_rmutex)
#define UNLOCK_MUTEX_R(env)	pthread_mutex_unlock((env)->me_rmutex)
#define LOCK_MUTEX_W(env)	pthread_mutex_lock((env)->me_wmutex)
#define UNLOCK_MUTEX_W(env)	pthread_mutex_unlock((env)->me_wmutex)
Howard Chu's avatar
Howard Chu committed
198
#define getpid()	GetCurrentProcessId()
199
#define	MDB_FDATASYNC(fd)	(!FlushFileBuffers(fd))
200
#define	MDB_MSYNC(addr,len,flags)	(!FlushViewOfFile(addr,len))
Howard Chu's avatar
Howard Chu committed
201
#define	ErrCode()	GetLastError()
Hallvard Furuseth's avatar
Hallvard Furuseth committed
202
#define GET_PAGESIZE(x) {SYSTEM_INFO si; GetSystemInfo(&si); (x) = si.dwPageSize;}
203
#define	close(fd)	(CloseHandle(fd) ? 0 : -1)
Howard Chu's avatar
Howard Chu committed
204
#define	munmap(ptr,len)	UnmapViewOfFile(ptr)
Hallvard Furuseth's avatar
Hallvard Furuseth committed
205
#ifdef PROCESS_QUERY_LIMITED_INFORMATION
Hallvard Furuseth's avatar
Hallvard Furuseth committed
206
207
208
209
#define MDB_PROCESS_QUERY_LIMITED_INFORMATION PROCESS_QUERY_LIMITED_INFORMATION
#else
#define MDB_PROCESS_QUERY_LIMITED_INFORMATION 0x1000
#endif
210
#define	Z	"I"
Howard Chu's avatar
Howard Chu committed
211
#else
Howard Chu's avatar
Howard Chu committed
212
213
214
#define THREAD_RET	void *
#define THREAD_CREATE(thr,start,arg)	pthread_create(&thr,NULL,start,arg)
#define THREAD_FINISH(thr)	pthread_join(thr,NULL)
215
#define	Z	"z"			/**< printf format modifier for size_t */
216

217
218
219
	/** For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile */
#define MDB_PIDLOCK			1

220
#ifdef MDB_USE_POSIX_SEM
221
222

#define LOCK_MUTEX_R(env)	mdb_sem_wait((env)->me_rmutex)
Howard Chu's avatar
Howard Chu committed
223
#define UNLOCK_MUTEX_R(env)	sem_post((env)->me_rmutex)
224
#define LOCK_MUTEX_W(env)	mdb_sem_wait((env)->me_wmutex)
Howard Chu's avatar
Howard Chu committed
225
#define UNLOCK_MUTEX_W(env)	sem_post((env)->me_wmutex)
226
227
228
229
230
231
232
233
234

static int
mdb_sem_wait(sem_t *sem)
{
   int rc;
   while ((rc = sem_wait(sem)) && (rc = errno) == EINTR) ;
   return rc;
}

Howard Chu's avatar
Howard Chu committed
235
#else
Howard Chu's avatar
Howard Chu committed
236
237
	/** Lock the reader mutex.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
238
#define LOCK_MUTEX_R(env)	pthread_mutex_lock(&(env)->me_txns->mti_mutex)
Howard Chu's avatar
Howard Chu committed
239
240
	/** Unlock the reader mutex.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
241
#define UNLOCK_MUTEX_R(env)	pthread_mutex_unlock(&(env)->me_txns->mti_mutex)
Howard Chu's avatar
Howard Chu committed
242
243
244
245
246

	/** Lock the writer mutex.
	 *	Only a single write transaction is allowed at a time. Other writers
	 *	will block waiting for this mutex.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
247
#define LOCK_MUTEX_W(env)	pthread_mutex_lock(&(env)->me_txns->mti_wmutex)
Howard Chu's avatar
Howard Chu committed
248
249
	/** Unlock the writer mutex.
	 */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
250
#define UNLOCK_MUTEX_W(env)	pthread_mutex_unlock(&(env)->me_txns->mti_wmutex)
251
#endif	/* MDB_USE_POSIX_SEM */
Howard Chu's avatar
Howard Chu committed
252
253
254

	/** Get the error code for the last failed system function.
	 */
Howard Chu's avatar
Howard Chu committed
255
#define	ErrCode()	errno
Howard Chu's avatar
Howard Chu committed
256

257
258
259
260
261
262
	/** 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
263
264
265
266
	/**	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
267
#define INVALID_HANDLE_VALUE	(-1)
Howard Chu's avatar
Howard Chu committed
268
269
270
271
272

	/** 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
273
#define	GET_PAGESIZE(x)	((x) = sysconf(_SC_PAGE_SIZE))
Howard Chu's avatar
Howard Chu committed
274
#endif
Howard Chu's avatar
Howard Chu committed
275

276
#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
Howard Chu's avatar
Howard Chu committed
277
#define MNAME_LEN	32
278
279
#else
#define MNAME_LEN	(sizeof(pthread_mutex_t))
Howard Chu's avatar
Howard Chu committed
280
281
#endif

282
/** @} */
Howard Chu's avatar
Howard Chu committed
283

284
#ifndef _WIN32
Howard Chu's avatar
Howard Chu committed
285
286
287
288
289
290
/**	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
291
292
293
294
295
296
 * 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
297
298
299
300
301
302
303
#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
304
305
306
307
308
309
310
311
312
313
314
315
#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
316
317
#endif

Howard Chu's avatar
Howard Chu committed
318
319
320
321
322
323
324
325
	/** 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.
	 */
326
typedef MDB_ID	pgno_t;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
327

328
329
330
	/** A transaction ID.
	 *	See struct MDB_txn.mt_txnid for details.
	 */
331
typedef MDB_ID	txnid_t;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
332

Howard Chu's avatar
Howard Chu committed
333
334
335
/** @defgroup debug	Debug Macros
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
336
#ifndef MDB_DEBUG
337
	/**	Enable debug output.  Needs variable argument macros (a C99 feature).
Howard Chu's avatar
Howard Chu committed
338
339
340
	 *	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
341
#define MDB_DEBUG 0
342
#endif
Howard Chu's avatar
Howard Chu committed
343

344
#if MDB_DEBUG
345
static int mdb_debug;
346
static txnid_t mdb_debug_start;
347

348
349
350
351
352
	/**	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
353
	fprintf(stderr, "%s:%d " fmt "\n", mdb_func_, __LINE__, __VA_ARGS__)
Howard Chu's avatar
Howard Chu committed
354
#else
355
# define DPRINTF(args)	((void) 0)
Howard Chu's avatar
Howard Chu committed
356
#endif
Howard Chu's avatar
Howard Chu committed
357
358
359
	/**	Print a debug string.
	 *	The string is printed literally, with no format processing.
	 */
360
#define DPUTS(arg)	DPRINTF(("%s", arg))
361
362
363
	/** 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
364
/** @} */
Howard Chu's avatar
Howard Chu committed
365

366
367
	/**	@brief The maximum size of a database page.
	 *
Hallvard Furuseth's avatar
Hallvard Furuseth committed
368
	 *	This is 32k, since it must fit in #MDB_page.%mp_upper.
369
370
371
372
	 *
	 *	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
373
374
375
376
377
378
379
380
	 *
	 *	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.
	 */
381
#define MAX_PAGESIZE	 0x8000
Howard Chu's avatar
Howard Chu committed
382
383
384
385
386
387
388
389
390
391
392
393
394

	/** 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
395
#define MDB_MINKEYS	 2
Howard Chu's avatar
Howard Chu committed
396

Howard Chu's avatar
Howard Chu committed
397
	/**	A stamp that identifies a file as an LMDB file.
Howard Chu's avatar
Howard Chu committed
398
399
400
	 *	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
401
#define MDB_MAGIC	 0xBEEFC0DE
Howard Chu's avatar
Howard Chu committed
402

403
404
405
406
	/**	The version number for a database's datafile format. */
#define MDB_DATA_VERSION	 1
	/**	The version number for a database's lockfile format. */
#define MDB_LOCK_VERSION	 1
Howard Chu's avatar
Howard Chu committed
407

408
	/**	@brief The max size of a key we can write, or 0 for dynamic max.
409
	 *
410
411
412
	 *	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.
413
	 *
414
415
416
	 *	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
417
	 */
418
419
#ifndef MDB_MAXKEYSIZE
#define MDB_MAXKEYSIZE	 511
420
421
422
423
424
425
426
#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)
427
#endif
Howard Chu's avatar
Howard Chu committed
428

429
430
431
432
433
434
	/**	@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
435
#if MDB_DEBUG
436
437
438
439
	/**	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
440
441
442
443
	/**	A key buffer.
	 *	@ingroup debug
	 *	This is used for printing a hex dump of a key's contents.
	 */
444
#define DKBUF	char kbuf[DKBUF_MAXKEYSIZE*2+1]
Howard Chu's avatar
Howard Chu committed
445
446
447
448
	/**	Display a key in hex.
	 *	@ingroup debug
	 *	Invoke a function to display a key in hex.
	 */
Howard Chu's avatar
Howard Chu committed
449
450
#define	DKEY(x)	mdb_dkey(x, kbuf)
#else
Howard Chu's avatar
Howard Chu committed
451
#define	DKBUF
Howard Chu's avatar
Howard Chu committed
452
#define DKEY(x)	0
Howard Chu's avatar
Howard Chu committed
453
#endif
Howard Chu's avatar
Howard Chu committed
454

Howard Chu's avatar
Howard Chu committed
455
456
457
	/** An invalid page number.
	 *	Mainly used to denote an empty tree.
	 */
458
#define P_INVALID	 (~(pgno_t)0)
Howard Chu's avatar
Howard Chu committed
459

460
	/** Test if the flags \b f are set in a flag word \b w. */
Howard Chu's avatar
Howard Chu committed
461
462
#define F_ISSET(w, f)	 (((w) & (f)) == (f))

463
464
465
	/** 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
466
467
468
469
	/**	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
470
471
typedef uint16_t	 indx_t;

Howard Chu's avatar
Howard Chu committed
472
473
474
475
	/**	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
476
477
#define DEFAULT_MAPSIZE	1048576

Howard Chu's avatar
Howard Chu committed
478
479
480
481
482
483
484
/**	@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
485
486
 *	If #MDB_NOTLS is set, the slot address is not saved in thread-specific data.
 *
Howard Chu's avatar
Howard Chu committed
487
488
 *	No reader table is used if the database is on a read-only filesystem, or
 *	if #MDB_NOLOCK is set.
489
 *
Howard Chu's avatar
Howard Chu committed
490
491
492
 *	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
493
494
 *	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
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
 *	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
529
#ifndef CACHELINE
Howard Chu's avatar
Howard Chu committed
530
#define CACHELINE	64
Howard Chu's avatar
Howard Chu committed
531
532
#endif

Howard Chu's avatar
Howard Chu committed
533
534
535
536
537
538
539
540
	/**	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
541
typedef struct MDB_rxbody {
542
	/**	Current Transaction ID when this transaction began, or (txnid_t)-1.
Howard Chu's avatar
Howard Chu committed
543
544
545
546
547
548
	 *	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.
	 */
549
	txnid_t		mrb_txnid;
Howard Chu's avatar
Howard Chu committed
550
	/** The process ID of the process owning this reader txn. */
Howard Chu's avatar
Howard Chu committed
551
	MDB_PID_T	mrb_pid;
Howard Chu's avatar
Howard Chu committed
552
	/** The thread ID of the thread owning this txn. */
Howard Chu's avatar
Howard Chu committed
553
	MDB_THR_T	mrb_tid;
Howard Chu's avatar
Howard Chu committed
554
555
} MDB_rxbody;

Howard Chu's avatar
Howard Chu committed
556
	/** The actual reader record, with cacheline padding. */
Howard Chu's avatar
Howard Chu committed
557
typedef struct MDB_reader {
Howard Chu's avatar
Howard Chu committed
558
559
	union {
		MDB_rxbody mrx;
Howard Chu's avatar
Howard Chu committed
560
		/** shorthand for mrb_txnid */
Howard Chu's avatar
Howard Chu committed
561
562
563
#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
564
		/** cache line alignment */
Howard Chu's avatar
Howard Chu committed
565
566
		char pad[(sizeof(MDB_rxbody)+CACHELINE-1) & ~(CACHELINE-1)];
	} mru;
Howard Chu's avatar
Howard Chu committed
567
568
} MDB_reader;

Howard Chu's avatar
Howard Chu committed
569
570
571
572
573
574
575
	/** 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
576
	 *	processes can grab them. This same approach is also used on
Howard Chu's avatar
Howard Chu committed
577
	 *	MacOSX/Darwin (using named semaphores) since MacOSX doesn't support
Howard Chu's avatar
Howard Chu committed
578
579
580
581
	 *	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
582
	 */
Howard Chu's avatar
Howard Chu committed
583
typedef struct MDB_txbody {
Howard Chu's avatar
Howard Chu committed
584
		/** Stamp identifying this as an LMDB file. It must be set
Howard Chu's avatar
Howard Chu committed
585
		 *	to #MDB_MAGIC. */
Howard Chu's avatar
Howard Chu committed
586
	uint32_t	mtb_magic;
587
588
		/** Format of this lock file. Must be set to #MDB_LOCK_FORMAT. */
	uint32_t	mtb_format;
589
#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
Howard Chu's avatar
Howard Chu committed
590
	char	mtb_rmname[MNAME_LEN];
Howard Chu's avatar
Howard Chu committed
591
#else
Howard Chu's avatar
Howard Chu committed
592
593
594
		/** Mutex protecting access to this table.
		 *	This is the reader lock that #LOCK_MUTEX_R acquires.
		 */
Howard Chu's avatar
Howard Chu committed
595
	pthread_mutex_t	mtb_mutex;
Howard Chu's avatar
Howard Chu committed
596
#endif
Howard Chu's avatar
Howard Chu committed
597
598
599
600
		/**	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.
		 */
601
	txnid_t		mtb_txnid;
Howard Chu's avatar
Howard Chu committed
602
603
604
605
		/** 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.
		 */
606
	unsigned	mtb_numreaders;
Howard Chu's avatar
Howard Chu committed
607
608
} MDB_txbody;

Howard Chu's avatar
Howard Chu committed
609
	/** The actual reader table definition. */
Howard Chu's avatar
Howard Chu committed
610
typedef struct MDB_txninfo {
Howard Chu's avatar
Howard Chu committed
611
612
613
	union {
		MDB_txbody mtb;
#define mti_magic	mt1.mtb.mtb_magic
614
#define mti_format	mt1.mtb.mtb_format
Howard Chu's avatar
Howard Chu committed
615
#define mti_mutex	mt1.mtb.mtb_mutex
Howard Chu's avatar
Howard Chu committed
616
#define mti_rmname	mt1.mtb.mtb_rmname
Howard Chu's avatar
Howard Chu committed
617
618
619
620
621
#define mti_txnid	mt1.mtb.mtb_txnid
#define mti_numreaders	mt1.mtb.mtb_numreaders
		char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
	} mt1;
	union {
622
#if defined(_WIN32) || defined(MDB_USE_POSIX_SEM)
Howard Chu's avatar
Howard Chu committed
623
		char mt2_wmname[MNAME_LEN];
Howard Chu's avatar
Howard Chu committed
624
625
#define	mti_wmname	mt2.mt2_wmname
#else
Howard Chu's avatar
Howard Chu committed
626
627
		pthread_mutex_t	mt2_wmutex;
#define mti_wmutex	mt2.mt2_wmutex
Howard Chu's avatar
Howard Chu committed
628
#endif
629
		char pad[(MNAME_LEN+CACHELINE-1) & ~(CACHELINE-1)];
Howard Chu's avatar
Howard Chu committed
630
631
	} mt2;
	MDB_reader	mti_readers[1];
Howard Chu's avatar
Howard Chu committed
632
} MDB_txninfo;
633
634
635
636
637
638
639

	/** Lockfile format signature: version, features and field layout */
#define MDB_LOCK_FORMAT \
	((uint32_t) \
	 ((MDB_LOCK_VERSION) \
	  /* Flags which describe functionality */ \
	  + (((MDB_PIDLOCK) != 0) << 16)))
Howard Chu's avatar
Howard Chu committed
640
/** @} */
Howard Chu's avatar
Howard Chu committed
641

Howard Chu's avatar
Howard Chu committed
642
/** Common header for all page types.
Howard Chu's avatar
Howard Chu committed
643
 * Overflow records occupy a number of contiguous pages with no
Howard Chu's avatar
Howard Chu committed
644
645
 * headers on any page after the first.
 */
Howard Chu's avatar
Howard Chu committed
646
typedef struct MDB_page {
647
648
#define	mp_pgno	mp_p.p_pgno
#define	mp_next	mp_p.p_next
Howard Chu's avatar
Howard Chu committed
649
	union {
650
651
652
		pgno_t		p_pgno;	/**< page number */
		void *		p_next;	/**< for in-memory list of freed structs */
	} mp_p;
Howard Chu's avatar
Howard Chu committed
653
	uint16_t	mp_pad;
Howard Chu's avatar
Howard Chu committed
654
655
656
657
658
/**	@defgroup mdb_page	Page Flags
 *	@ingroup internal
 *	Flags for the page headers.
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
659
660
661
662
#define	P_BRANCH	 0x01		/**< branch page */
#define	P_LEAF		 0x02		/**< leaf page */
#define	P_OVERFLOW	 0x04		/**< overflow page */
#define	P_META		 0x08		/**< meta page */
663
#define	P_DIRTY		 0x10		/**< dirty page, also set for #P_SUBP pages */
Howard Chu's avatar
Howard Chu committed
664
#define	P_LEAF2		 0x20		/**< for #MDB_DUPFIXED records */
Howard Chu's avatar
Howard Chu committed
665
#define	P_SUBP		 0x40		/**< for #MDB_DUPSORT sub-pages */
Howard Chu's avatar
Howard Chu committed
666
#define	P_LOOSE		 0x4000		/**< page was dirtied then freed, can be reused */
Howard Chu's avatar
Howard Chu committed
667
#define	P_KEEP		 0x8000		/**< leave this page alone during spill */
Howard Chu's avatar
Howard Chu committed
668
/** @} */
Howard Chu's avatar
Howard Chu committed
669
	uint16_t	mp_flags;		/**< @ref mdb_page */
670
671
672
#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
673
	union {
Howard Chu's avatar
Howard Chu committed
674
		struct {
675
676
677
678
679
			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
680
	indx_t		mp_ptrs[1];		/**< dynamic size */
Howard Chu's avatar
Howard Chu committed
681
682
} MDB_page;

Howard Chu's avatar
Howard Chu committed
683
	/** Size of the page header, excluding dynamic data at the end */
684
#define PAGEHDRSZ	 ((unsigned) offsetof(MDB_page, mp_ptrs))
Howard Chu's avatar
Howard Chu committed
685

Howard Chu's avatar
Howard Chu committed
686
687
688
689
	/** Address of first usable data byte in a page, after the header */
#define METADATA(p)	 ((void *)((char *)(p) + PAGEHDRSZ))

	/** Number of nodes on a page */
Howard Chu's avatar
Howard Chu committed
690
#define NUMKEYS(p)	 (((p)->mp_lower - PAGEHDRSZ) >> 1)
Howard Chu's avatar
Howard Chu committed
691
692

	/** The amount of space remaining in the page */
Howard Chu's avatar
Howard Chu committed
693
#define SIZELEFT(p)	 (indx_t)((p)->mp_upper - (p)->mp_lower)
Howard Chu's avatar
Howard Chu committed
694
695

	/** The percentage of space used in the page, in tenths of a percent. */
Howard Chu's avatar
Howard Chu committed
696
697
#define PAGEFILL(env, p) (1000L * ((env)->me_psize - PAGEHDRSZ - SIZELEFT(p)) / \
				((env)->me_psize - PAGEHDRSZ))
Howard Chu's avatar
Howard Chu committed
698
699
700
701
702
703
	/** 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
704
#define IS_LEAF(p)	 F_ISSET((p)->mp_flags, P_LEAF)
Howard Chu's avatar
Howard Chu committed
705
	/** Test if a page is a LEAF2 page */
Howard Chu's avatar
Howard Chu committed
706
#define IS_LEAF2(p)	 F_ISSET((p)->mp_flags, P_LEAF2)
Howard Chu's avatar
Howard Chu committed
707
	/** Test if a page is a branch page */
Howard Chu's avatar
Howard Chu committed
708
#define IS_BRANCH(p)	 F_ISSET((p)->mp_flags, P_BRANCH)
Howard Chu's avatar
Howard Chu committed
709
	/** Test if a page is an overflow page */
Howard Chu's avatar
Howard Chu committed
710
#define IS_OVERFLOW(p)	 F_ISSET((p)->mp_flags, P_OVERFLOW)
Howard Chu's avatar
Howard Chu committed
711
712
	/** 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
713

Howard Chu's avatar
Howard Chu committed
714
	/** The number of overflow pages needed to store the given size. */
715
#define OVPAGES(size, psize)	((PAGEHDRSZ-1 + (size)) / (psize) + 1)
Howard Chu's avatar
Howard Chu committed
716

717
718
719
	/** Link in #MDB_txn.%mt_loose_pages list */
#define NEXT_LOOSE_PAGE(p)		(*(MDB_page **)METADATA(p))

Howard Chu's avatar
Howard Chu committed
720
	/** Header for a single key/data pair within a page.
721
722
	 * 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
723
724
725
726
	 */
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
727
	 * is also used for pgno. (Branch nodes have no flags).
Howard Chu's avatar
Howard Chu committed
728
	 * They are in host byte order in case that lets some
729
	 * accesses be optimized into a 32-bit word access.
Howard Chu's avatar
Howard Chu committed
730
	 */
731
732
733
734
735
#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
736
737
738
739
740
/** @defgroup mdb_node Node Flags
 *	@ingroup internal
 *	Flags for node headers.
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
741
742
743
#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
744
745

/** valid flags for #mdb_node_add() */
746
#define	NODE_ADD_FLAGS	(F_DUPDATA|F_SUBDATA|MDB_RESERVE|MDB_APPEND)
Howard Chu's avatar
Howard Chu committed
747

Howard Chu's avatar
Howard Chu committed
748
749
/** @} */
	unsigned short	mn_flags;		/**< @ref mdb_node */
Howard Chu's avatar
Howard Chu committed
750
751
752
753
754
755
756
	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)

757
758
759
	/** 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
760
	/** Size of a node in a branch page with a given key.
Howard Chu's avatar
Howard Chu committed
761
762
763
764
	 *	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
765
	/** Size of a node in a leaf page with a given key and data.
Howard Chu's avatar
Howard Chu committed
766
767
768
769
	 *	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
770
	/** Address of node \b i in page \b p */
Howard Chu's avatar
Howard Chu committed
771
772
773
774
775
776
777
778
779
#define NODEPTR(p, i)	 ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i]))

	/** 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 */
780
781
782
#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
783
784
785
	/** Set the page number in a branch node */
#define SETPGNO(node,pgno)	do { \
	(node)->mn_lo = (pgno) & 0xffff; (node)->mn_hi = (pgno) >> 16; \
786
	if (PGNO_TOPWORD) (node)->mn_flags = (pgno) >> PGNO_TOPWORD; } while(0)
Howard Chu's avatar
Howard Chu committed
787
788
789
790
791
792
793
794
795

	/** 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
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
	/** 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
820
821
822
823
824
825
	/** 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
826
827
828
829
830
831
	/** 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
832
833

	/** Information about a single database in the environment. */
Howard Chu's avatar
Howard Chu committed
834
typedef struct MDB_db {
Howard Chu's avatar
Howard Chu committed
835
	uint32_t	md_pad;		/**< also ksize for LEAF2 pages */
836
	uint16_t	md_flags;	/**< @ref mdb_dbi_open */
Howard Chu's avatar
Howard Chu committed
837
	uint16_t	md_depth;	/**< depth of this tree */
838
839
840
841
	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
842
	pgno_t		md_root;		/**< the root page of this tree */
Howard Chu's avatar
Howard Chu committed
843
844
} MDB_db;

845
	/** mdb_dbi_open flags */
846
847
#define MDB_VALID	0x8000		/**< DB handle is valid, for me_dbflags */
#define PERSISTENT_FLAGS	(0xffff & ~(MDB_VALID))
848
849
850
#define VALID_FLAGS	(MDB_REVERSEKEY|MDB_DUPSORT|MDB_INTEGERKEY|MDB_DUPFIXED|\
	MDB_INTEGERDUP|MDB_REVERSEDUP|MDB_CREATE)

Howard Chu's avatar
Howard Chu committed
851
	/** Handle for the DB used to track free pages. */
Howard Chu's avatar
Howard Chu committed
852
#define	FREE_DBI	0
Howard Chu's avatar
Howard Chu committed
853
	/** Handle for the default DB. */
Howard Chu's avatar
Howard Chu committed
854
855
#define	MAIN_DBI	1

856
857
858
859
	/** 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
860
typedef struct MDB_meta {
Howard Chu's avatar
Howard Chu committed
861
		/** Stamp identifying this as an LMDB file. It must be set
Howard Chu's avatar
Howard Chu committed
862
		 *	to #MDB_MAGIC. */
Howard Chu's avatar
Howard Chu committed
863
	uint32_t	mm_magic;
864
		/** Version number of this lock file. Must be set to #MDB_DATA_VERSION. */
Howard Chu's avatar
Howard Chu committed
865
	uint32_t	mm_version;
Howard Chu's avatar
Howard Chu committed
866
867
868
869
	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
870
#define	mm_psize	mm_dbs[0].md_pad
Howard Chu's avatar
Howard Chu committed
871
	/** Any persistent environment flags. @ref mdb_env */
Howard Chu's avatar
Howard Chu committed
872
#define	mm_flags	mm_dbs[0].md_flags
Howard Chu's avatar
Howard Chu committed
873
	pgno_t		mm_last_pg;			/**< last used page in file */
874
	txnid_t		mm_txnid;			/**< txnid that committed this page */
Howard Chu's avatar
Howard Chu committed
875
876
} MDB_meta;

877
	/** Buffer for a stack-allocated meta page.
878
879
880
881
	 *	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.
	 */
882
typedef union MDB_metabuf {
883
884
885
886
887
	MDB_page	mb_page;
	struct {
		char		mm_pad[PAGEHDRSZ];
		MDB_meta	mm_meta;
	} mb_metabuf;
888
} MDB_metabuf;
889

Howard Chu's avatar
Howard Chu committed
890
891
892
893
894
895
896
897
898
	/** 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 */
899
	void		*md_relctx;		/**< user-provided context for md_rel */
Howard Chu's avatar
Howard Chu committed
900
} MDB_dbx;
Howard Chu's avatar
Howard Chu committed
901

Howard Chu's avatar
Howard Chu committed
902
903
904
905
	/** A database transaction.
	 *	Every operation requires a transaction handle.
	 */
struct MDB_txn {
906
907
	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
908
909
910
911
912
	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.
	 */
913
	txnid_t		mt_txnid;
Howard Chu's avatar
Howard Chu committed
914
915
916
	MDB_env		*mt_env;		/**< the DB environment */
	/** The list of pages that became unused during this transaction.
	 */
917
	MDB_IDL		mt_free_pgs;
Howard Chu's avatar
Howard Chu committed
918
	/** The list of loose pages that became unused and may be reused
919
	 *	in this transaction, linked through #NEXT_LOOSE_PAGE(page).
Howard Chu's avatar
Howard Chu committed
920
921
	 */
	MDB_page	*mt_loose_pgs;
Hallvard Furuseth's avatar
Hallvard Furuseth committed
922
	/** The sorted list of dirty pages we temporarily wrote to disk
923
924
	 *	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
925
926
	 */
	MDB_IDL		mt_spill_pgs;
Howard Chu's avatar
Howard Chu committed
927
	union {
Hallvard Furuseth's avatar
Hallvard Furuseth committed
928
929
930
931
		/** 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
932
933
934
935
936
	} 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;
Howard Chu's avatar
Howard Chu committed
937
938
939
940
/** @defgroup mt_dbflag	Transaction DB Flags
 *	@ingroup internal
 * @{
 */
941
#define DB_DIRTY	0x01		/**< DB was modified or is DUPSORT data */
942
943
#define DB_STALE	0x02		/**< Named-DB record is older than txnID */
#define DB_NEW		0x04		/**< Named-DB handle opened in this txn */
944
#define DB_VALID	0x08		/**< DB handle is valid, see also #MDB_VALID */
Howard Chu's avatar
Howard Chu committed
945
/** @} */
946
	/** In write txns, array of cursors for each DB */
Howard Chu's avatar
Howard Chu committed
947
	MDB_cursor	**mt_cursors;
Howard Chu's avatar
Howard Chu committed
948
949
	/** Array of flags for each DB */
	unsigned char	*mt_dbflags;
Howard Chu's avatar
Howard Chu committed
950
951
952
	/**	Number of DB records in use. This number only ever increments;
	 *	we don't decrement it when individual DB handles are closed.
	 */
953
	MDB_dbi		mt_numdbs;
Howard Chu's avatar
Howard Chu committed
954

Howard Chu's avatar
Howard Chu committed
955
956
957
958
/** @defgroup mdb_txn	Transaction Flags
 *	@ingroup internal
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
959
#define MDB_TXN_RDONLY		0x01		/**< read-only transaction */
960
#define MDB_TXN_ERROR		0x02		/**< txn is unusable after an error */
961
#define MDB_TXN_DIRTY		0x04		/**< must write, even if dirty list is empty */
Howard Chu's avatar
Howard Chu committed
962
#define MDB_TXN_SPILLS		0x08		/**< txn or a parent has spilled pages */
Howard Chu's avatar
Howard Chu committed
963
964
/** @} */
	unsigned int	mt_flags;		/**< @ref mdb_txn */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
965
	/** #dirty_list room: Array size - \#dirty pages visible to this txn.
966
967
968
969
	 *	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.
	 */
970
	unsigned int	mt_dirty_room;
Howard Chu's avatar
Howard Chu committed
971
};
Howard Chu's avatar
Howard Chu committed
972

Howard Chu's avatar
Howard Chu committed
973
/** Enough space for 2^32 nodes with minimum of 2 keys per node. I.e., plenty.
974
975
976
 * 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
977
#define CURSOR_STACK		 32
Howard Chu's avatar
Howard Chu committed
978

Howard Chu's avatar
Howard Chu committed
979
struct MDB_xcursor;
980

981
982
983
984
985
986
987
988
	/** Cursors are used for all DB operations.
	 *	A cursor holds a path of (page pointer, key index) from the DB
	 *	root to a position in the DB, plus other state. #MDB_DUPSORT
	 *	cursors include an xcursor to the current data item. Write txns
	 *	track their cursors and keep them up to date when data moves.
	 *	Exception: An xcursor's pointer to a #P_SUBP page can be stale.
	 *	(A node with #F_DUPDATA but no #F_SUBDATA contains a subpage).
	 */
Howard Chu's avatar
Howard Chu committed
989
struct MDB_cursor {
Howard Chu's avatar
Howard Chu committed
990
991
	/** Next cursor on this DB in this txn */
	MDB_cursor	*mc_next;
992
993
	/** Backup of the original cursor if this cursor is a shadow */
	MDB_cursor	*mc_backup;
Howard Chu's avatar
Howard Chu committed
994
	/** Context used for databases with #MDB_DUPSORT, otherwise NULL */
Howard Chu's avatar
Howard Chu committed
995
	struct MDB_xcursor	*mc_xcursor;
Howard Chu's avatar
Howard Chu committed
996
	/** The transaction that owns this cursor */
Howard Chu's avatar
Howard Chu committed
997
	MDB_txn		*mc_txn;
Howard Chu's avatar
Howard Chu committed
998
	/** The database handle this cursor operates on */
Howard Chu's avatar
Howard Chu committed
999
	MDB_dbi		mc_dbi;
1000
1001
1002
1003
	/** The database record for this cursor */
	MDB_db		*mc_db;
	/** The database auxiliary record for this cursor */
	MDB_dbx		*mc_dbx;
Howard Chu's avatar
Howard Chu committed
1004
1005
	/** The @ref mt_dbflag for this database */
	unsigned char	*mc_dbflag;
Howard Chu's avatar
Howard Chu committed
1006
	unsigned short 	mc_snum;	/**< number of pushed pages */
Hallvard Furuseth's avatar
Hallvard Furuseth committed
1007
	unsigned short	mc_top;		/**< index of top page, normally mc_snum-1 */
Howard Chu's avatar
Howard Chu committed
1008
1009
1010
1011
1012
/** @defgroup mdb_cursor	Cursor Flags
 *	@ingroup internal
 *	Cursor state flags.
 *	@{
 */
Howard Chu's avatar
Howard Chu committed
1013
1014
#define C_INITIALIZED	0x01	/**< cursor has been initialized and is valid */
#define C_EOF	0x02			/**< No more data */
Howard Chu's avatar
Howard Chu committed
1015
#define C_SUB	0x04			/**< Cursor is a sub-cursor */
1016
#define C_DEL	0x08			/**< last op was a cursor_del */
Howard Chu's avatar
Howard Chu committed
1017
#define C_SPLITTING	0x20		/**< Cursor is in page_split */
1018
#define C_UNTRACK	0x40		/**< Un-track cursor when closing */
Howard Chu's avatar
Howard Chu committed
1019
1020
/** @} */
	unsigned int	mc_flags;	/**< @ref mdb_cursor */
Howard Chu's avatar
Howard Chu committed
1021
1022
	MDB_page	*mc_pg[CURSOR_STACK];	/**< stack of pushed pages */
	indx_t		mc_ki[CURSOR_STACK];	/**< stack of page indices */
Howard Chu's avatar
Howard Chu committed
1023
1024
};

Howard Chu's avatar
Howard Chu committed
1025
1026
1027
1028
	/** Context for sorted-dup records.
	 *	We could have gone to a fully recursive design, with arbitrarily
	 *	deep nesting of sub-databases. But for now we only handle these
	 *	levels - main DB, optional sub-DB, sorted-duplicate DB.
1029
	 */
Howard Chu's avatar
Howard Chu committed
1030
typedef struct MDB_xcursor {
Howard Chu's avatar
Howard Chu committed
1031
	/** A sub-cursor for traversing the Dup DB */
Howard Chu's avatar
Howard Chu committed
1032
	MDB_cursor mx_cursor;
1033
1034
1035
1036
	/** The database record for this Dup DB */
	MDB_db	mx_db;
	/**	The auxiliary DB record for this Dup DB */
	MDB_dbx	mx_dbx;
Howard Chu's avatar
Howard Chu committed
1037
1038
	/** The @ref mt_dbflag for this Dup DB */
	unsigned char mx_dbflag;
Howard Chu's avatar
Howard Chu committed
1039
1040
} MDB_xcursor;

1041
1042
	/** State of FreeDB old pages, stored in the MDB_env */
typedef struct MDB_pgstate {
1043
1044
	pgno_t		*mf_pghead;	/**< Reclaimed freeDB pages, or NULL before use */
	txnid_t		mf_pglast;	/**< ID of last used record, or 0 if !mf_pghead */
1045
1046
} MDB_pgstate;

Howard Chu's avatar
Howard Chu committed
1047
	/** The database environment. */
Howard Chu's avatar
Howard Chu committed
1048
struct MDB_env {
Howard Chu's avatar
Howard Chu committed
1049
1050
1051
	HANDLE		me_fd;		/**< The main data file */
	HANDLE		me_lfd;		/**< The lock file */
	HANDLE		me_mfd;			/**< just for writing the meta pages */
Howard Chu's avatar
Howard Chu committed
1052
	/** Failed to update the meta page. Probably an I/O error. */
Howard Chu's avatar
Howard Chu committed
1053
#define	MDB_FATAL_ERROR	0x80000000U
Hallvard Furuseth's avatar
Hallvard Furuseth committed
1054
1055
	/** Some fields are initialized. */
#define	MDB_ENV_ACTIVE	0x20000000U
1056
1057
	/** me_txkey is set */
#define	MDB_ENV_TXKEY	0x10000000U
Howard Chu's avatar
Howard Chu committed
1058
	uint32_t 	me_flags;		/**< @ref mdb_env */
1059
1060
	unsigned int	me_psize;	/**< DB page size, inited from me_os_psize */
	unsigned int	me_os_psize;	/**< OS page size, from #GET_PAGESIZE */
Howard Chu's avatar
Howard Chu committed
1061
	unsigned int	me_maxreaders;	/**< size of the reader table */
1062
	unsigned int	me_numreaders;	/**< max numreaders set by this env */
1063
1064
	MDB_dbi		me_numdbs;		/**< number of DBs opened */
	MDB_dbi		me_maxdbs;		/**< size of the DB table */
Howard Chu's avatar
Howard Chu committed
1065
	MDB_PID_T	me_pid;		/**< process ID of this env */
Howard Chu's avatar
Howard Chu committed
1066
1067
	char		*me_path;		/**< path to the DB files */
	char		*me_map;		/**< the memory map of the data file */
1068
	MDB_txninfo	*me_txns;		/**< the memory map of the lock file or NULL */
Howard Chu's avatar
Howard Chu committed
1069
	MDB_meta	*me_metas[2];	/**< pointers to the two meta pages */
1070
	void		*me_pbuf;		/**< scratch area for DUPSORT put() */
Howard Chu's avatar
Howard Chu committed
1071
1072
1073
1074
1075
	MDB_txn		*me_txn;		/**< current write transaction */
	size_t		me_mapsize;		/**< size of the data memory map */
	off_t		me_size;		/**< current file size */
	pgno_t		me_maxpg;		/**< me_mapsize / me_psize */
	MDB_dbx		*me_dbxs;		/**< array of static DB info */
1076
	uint16_t	*me_dbflags;	/**< array of flags from MDB_db.md_flags */
Howard Chu's avatar
Howard Chu committed
1077
	pthread_key_t	me_txkey;	/**< thread-key for readers */