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xlog_internal.h
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1 /*
2  * xlog_internal.h
3  *
4  * PostgreSQL write-ahead log internal declarations
5  *
6  * NOTE: this file is intended to contain declarations useful for
7  * manipulating the XLOG files directly, but it is not supposed to be
8  * needed by rmgr routines (redo support for individual record types).
9  * So the XLogRecord typedef and associated stuff appear in xlogrecord.h.
10  *
11  * Note: This file must be includable in both frontend and backend contexts,
12  * to allow stand-alone tools like pg_receivewal to deal with WAL files.
13  *
14  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
15  * Portions Copyright (c) 1994, Regents of the University of California
16  *
17  * src/include/access/xlog_internal.h
18  */
19 #ifndef XLOG_INTERNAL_H
20 #define XLOG_INTERNAL_H
21 
22 #include "access/xlogdefs.h"
23 #include "access/xlogreader.h"
24 #include "datatype/timestamp.h"
25 #include "lib/stringinfo.h"
26 #include "pgtime.h"
27 #include "storage/block.h"
28 #include "storage/relfilenode.h"
29 
30 
31 /*
32  * Each page of XLOG file has a header like this:
33  */
34 #define XLOG_PAGE_MAGIC 0xD097 /* can be used as WAL version indicator */
35 
36 typedef struct XLogPageHeaderData
37 {
38  uint16 xlp_magic; /* magic value for correctness checks */
39  uint16 xlp_info; /* flag bits, see below */
40  TimeLineID xlp_tli; /* TimeLineID of first record on page */
41  XLogRecPtr xlp_pageaddr; /* XLOG address of this page */
42 
43  /*
44  * When there is not enough space on current page for whole record, we
45  * continue on the next page. xlp_rem_len is the number of bytes
46  * remaining from a previous page.
47  *
48  * Note that xl_rem_len includes backup-block data; that is, it tracks
49  * xl_tot_len not xl_len in the initial header. Also note that the
50  * continuation data isn't necessarily aligned.
51  */
52  uint32 xlp_rem_len; /* total len of remaining data for record */
54 
55 #define SizeOfXLogShortPHD MAXALIGN(sizeof(XLogPageHeaderData))
56 
58 
59 /*
60  * When the XLP_LONG_HEADER flag is set, we store additional fields in the
61  * page header. (This is ordinarily done just in the first page of an
62  * XLOG file.) The additional fields serve to identify the file accurately.
63  */
64 typedef struct XLogLongPageHeaderData
65 {
66  XLogPageHeaderData std; /* standard header fields */
67  uint64 xlp_sysid; /* system identifier from pg_control */
68  uint32 xlp_seg_size; /* just as a cross-check */
69  uint32 xlp_xlog_blcksz; /* just as a cross-check */
71 
72 #define SizeOfXLogLongPHD MAXALIGN(sizeof(XLogLongPageHeaderData))
73 
75 
76 /* When record crosses page boundary, set this flag in new page's header */
77 #define XLP_FIRST_IS_CONTRECORD 0x0001
78 /* This flag indicates a "long" page header */
79 #define XLP_LONG_HEADER 0x0002
80 /* This flag indicates backup blocks starting in this page are optional */
81 #define XLP_BKP_REMOVABLE 0x0004
82 /* All defined flag bits in xlp_info (used for validity checking of header) */
83 #define XLP_ALL_FLAGS 0x0007
84 
85 #define XLogPageHeaderSize(hdr) \
86  (((hdr)->xlp_info & XLP_LONG_HEADER) ? SizeOfXLogLongPHD : SizeOfXLogShortPHD)
87 
88 /* wal_segment_size can range from 1MB to 1GB */
89 #define WalSegMinSize 1024 * 1024
90 #define WalSegMaxSize 1024 * 1024 * 1024
91 /* default number of min and max wal segments */
92 #define DEFAULT_MIN_WAL_SEGS 5
93 #define DEFAULT_MAX_WAL_SEGS 64
94 
95 /* check that the given size is a valid wal_segment_size */
96 #define IsPowerOf2(x) (x > 0 && ((x) & ((x)-1)) == 0)
97 #define IsValidWalSegSize(size) \
98  (IsPowerOf2(size) && \
99  ((size) >= WalSegMinSize && (size) <= WalSegMaxSize))
100 
101 #define XLogSegmentsPerXLogId(wal_segsz_bytes) \
102  (UINT64CONST(0x100000000) / (wal_segsz_bytes))
103 
104 #define XLogSegNoOffsetToRecPtr(segno, offset, dest, wal_segsz_bytes) \
105  (dest) = (segno) * (wal_segsz_bytes) + (offset)
106 
107 #define XLogSegmentOffset(xlogptr, wal_segsz_bytes) \
108  ((xlogptr) & ((wal_segsz_bytes) - 1))
109 
110 /*
111  * Compute a segment number from an XLogRecPtr.
112  *
113  * For XLByteToSeg, do the computation at face value. For XLByteToPrevSeg,
114  * a boundary byte is taken to be in the previous segment. This is suitable
115  * for deciding which segment to write given a pointer to a record end,
116  * for example.
117  */
118 #define XLByteToSeg(xlrp, logSegNo, wal_segsz_bytes) \
119  logSegNo = (xlrp) / (wal_segsz_bytes)
120 
121 #define XLByteToPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
122  logSegNo = ((xlrp) - 1) / (wal_segsz_bytes)
123 
124 /*
125  * Is an XLogRecPtr within a particular XLOG segment?
126  *
127  * For XLByteInSeg, do the computation at face value. For XLByteInPrevSeg,
128  * a boundary byte is taken to be in the previous segment.
129  */
130 #define XLByteInSeg(xlrp, logSegNo, wal_segsz_bytes) \
131  (((xlrp) / (wal_segsz_bytes)) == (logSegNo))
132 
133 #define XLByteInPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
134  ((((xlrp) - 1) / (wal_segsz_bytes)) == (logSegNo))
135 
136 /* Check if an XLogRecPtr value is in a plausible range */
137 #define XRecOffIsValid(xlrp) \
138  ((xlrp) % XLOG_BLCKSZ >= SizeOfXLogShortPHD)
139 
140 /*
141  * The XLog directory and control file (relative to $PGDATA)
142  */
143 #define XLOGDIR "pg_wal"
144 #define XLOG_CONTROL_FILE "global/pg_control"
145 
146 /*
147  * These macros encapsulate knowledge about the exact layout of XLog file
148  * names, timeline history file names, and archive-status file names.
149  */
150 #define MAXFNAMELEN 64
151 
152 /* Length of XLog file name */
153 #define XLOG_FNAME_LEN 24
154 
155 #define XLogFileName(fname, tli, logSegNo, wal_segsz_bytes) \
156  snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, \
157  (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
158  (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)))
159 
160 #define XLogFileNameById(fname, tli, log, seg) \
161  snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, log, seg)
162 
163 #define IsXLogFileName(fname) \
164  (strlen(fname) == XLOG_FNAME_LEN && \
165  strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN)
166 
167 /*
168  * XLOG segment with .partial suffix. Used by pg_receivewal and at end of
169  * archive recovery, when we want to archive a WAL segment but it might not
170  * be complete yet.
171  */
172 #define IsPartialXLogFileName(fname) \
173  (strlen(fname) == XLOG_FNAME_LEN + strlen(".partial") && \
174  strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN && \
175  strcmp((fname) + XLOG_FNAME_LEN, ".partial") == 0)
176 
177 #define XLogFromFileName(fname, tli, logSegNo, wal_segsz_bytes) \
178  do { \
179  uint32 log; \
180  uint32 seg; \
181  sscanf(fname, "%08X%08X%08X", tli, &log, &seg); \
182  *logSegNo = (uint64) log * XLogSegmentsPerXLogId(wal_segsz_bytes) + seg; \
183  } while (0)
184 
185 #define XLogFilePath(path, tli, logSegNo, wal_segsz_bytes) \
186  snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X", tli, \
187  (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
188  (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)))
189 
190 #define TLHistoryFileName(fname, tli) \
191  snprintf(fname, MAXFNAMELEN, "%08X.history", tli)
192 
193 #define IsTLHistoryFileName(fname) \
194  (strlen(fname) == 8 + strlen(".history") && \
195  strspn(fname, "0123456789ABCDEF") == 8 && \
196  strcmp((fname) + 8, ".history") == 0)
197 
198 #define TLHistoryFilePath(path, tli) \
199  snprintf(path, MAXPGPATH, XLOGDIR "/%08X.history", tli)
200 
201 #define StatusFilePath(path, xlog, suffix) \
202  snprintf(path, MAXPGPATH, XLOGDIR "/archive_status/%s%s", xlog, suffix)
203 
204 #define BackupHistoryFileName(fname, tli, logSegNo, startpoint, wal_segsz_bytes) \
205  snprintf(fname, MAXFNAMELEN, "%08X%08X%08X.%08X.backup", tli, \
206  (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
207  (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)), \
208  (uint32) (XLogSegmentOffset(startpoint, wal_segsz_bytes)))
209 
210 #define IsBackupHistoryFileName(fname) \
211  (strlen(fname) > XLOG_FNAME_LEN && \
212  strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN && \
213  strcmp((fname) + strlen(fname) - strlen(".backup"), ".backup") == 0)
214 
215 #define BackupHistoryFilePath(path, tli, logSegNo, startpoint, wal_segsz_bytes) \
216  snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X.%08X.backup", tli, \
217  (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
218  (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)), \
219  (uint32) (XLogSegmentOffset((startpoint), wal_segsz_bytes)))
220 
221 /*
222  * Information logged when we detect a change in one of the parameters
223  * important for Hot Standby.
224  */
225 typedef struct xl_parameter_change
226 {
235 
236 /* logs restore point */
237 typedef struct xl_restore_point
238 {
242 
243 /* End of recovery mark, when we don't do an END_OF_RECOVERY checkpoint */
244 typedef struct xl_end_of_recovery
245 {
247  TimeLineID ThisTimeLineID; /* new TLI */
248  TimeLineID PrevTimeLineID; /* previous TLI we forked off from */
250 
251 /*
252  * The functions in xloginsert.c construct a chain of XLogRecData structs
253  * to represent the final WAL record.
254  */
255 typedef struct XLogRecData
256 {
257  struct XLogRecData *next; /* next struct in chain, or NULL */
258  char *data; /* start of rmgr data to include */
259  uint32 len; /* length of rmgr data to include */
260 } XLogRecData;
261 
262 /*
263  * Recovery target action.
264  */
265 typedef enum
266 {
271 
272 /*
273  * Method table for resource managers.
274  *
275  * This struct must be kept in sync with the PG_RMGR definition in
276  * rmgr.c.
277  *
278  * rm_identify must return a name for the record based on xl_info (without
279  * reference to the rmid). For example, XLOG_BTREE_VACUUM would be named
280  * "VACUUM". rm_desc can then be called to obtain additional detail for the
281  * record, if available (e.g. the last block).
282  *
283  * rm_mask takes as input a page modified by the resource manager and masks
284  * out bits that shouldn't be flagged by wal_consistency_checking.
285  *
286  * RmgrTable[] is indexed by RmgrId values (see rmgrlist.h).
287  */
288 typedef struct RmgrData
289 {
290  const char *rm_name;
291  void (*rm_redo) (XLogReaderState *record);
292  void (*rm_desc) (StringInfo buf, XLogReaderState *record);
293  const char *(*rm_identify) (uint8 info);
294  void (*rm_startup) (void);
295  void (*rm_cleanup) (void);
296  void (*rm_mask) (char *pagedata, BlockNumber blkno);
297 } RmgrData;
298 
299 extern const RmgrData RmgrTable[];
300 
301 /*
302  * Exported to support xlog switching from checkpointer
303  */
304 extern pg_time_t GetLastSegSwitchData(XLogRecPtr *lastSwitchLSN);
305 extern XLogRecPtr RequestXLogSwitch(bool mark_unimportant);
306 
307 extern void GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli);
308 
309 /*
310  * Exported for the functions in timeline.c and xlogarchive.c. Only valid
311  * in the startup process.
312  */
313 extern bool ArchiveRecoveryRequested;
314 extern bool InArchiveRecovery;
315 extern bool StandbyMode;
316 extern char *recoveryRestoreCommand;
317 
318 /*
319  * Prototypes for functions in xlogarchive.c
320  */
321 extern bool RestoreArchivedFile(char *path, const char *xlogfname,
322  const char *recovername, off_t expectedSize,
323  bool cleanupEnabled);
324 extern void ExecuteRecoveryCommand(char *command, char *commandName,
325  bool failOnerror);
326 extern void KeepFileRestoredFromArchive(char *path, char *xlogfname);
327 extern void XLogArchiveNotify(const char *xlog);
328 extern void XLogArchiveNotifySeg(XLogSegNo segno);
329 extern void XLogArchiveForceDone(const char *xlog);
330 extern bool XLogArchiveCheckDone(const char *xlog);
331 extern bool XLogArchiveIsBusy(const char *xlog);
332 extern bool XLogArchiveIsReady(const char *xlog);
333 extern bool XLogArchiveIsReadyOrDone(const char *xlog);
334 extern void XLogArchiveCleanup(const char *xlog);
335 
336 #endif /* XLOG_INTERNAL_H */
struct XLogLongPageHeaderData XLogLongPageHeaderData
void XLogArchiveCleanup(const char *xlog)
Definition: xlogarchive.c:752
bool XLogArchiveIsReadyOrDone(const char *xlog)
Definition: xlogarchive.c:704
void XLogArchiveNotifySeg(XLogSegNo segno)
Definition: xlogarchive.c:548
uint32 TimeLineID
Definition: xlogdefs.h:45
int64 pg_time_t
Definition: pgtime.h:23
void(* rm_mask)(char *pagedata, BlockNumber blkno)
struct xl_end_of_recovery xl_end_of_recovery
bool XLogArchiveCheckDone(const char *xlog)
Definition: xlogarchive.c:619
TimeLineID PrevTimeLineID
struct xl_parameter_change xl_parameter_change
int64 TimestampTz
Definition: timestamp.h:39
XLogRecPtr RequestXLogSwitch(bool mark_unimportant)
Definition: xlog.c:9490
void ExecuteRecoveryCommand(char *command, char *commandName, bool failOnerror)
Definition: xlogarchive.c:330
unsigned char uint8
Definition: c.h:256
void(* rm_redo)(XLogReaderState *record)
pg_time_t GetLastSegSwitchData(XLogRecPtr *lastSwitchLSN)
Definition: xlog.c:8353
bool StandbyMode
Definition: xlog.c:279
XLogPageHeaderData * XLogPageHeader
Definition: xlog_internal.h:57
uint32 BlockNumber
Definition: block.h:31
void XLogArchiveNotify(const char *xlog)
Definition: xlogarchive.c:514
XLogLongPageHeaderData * XLogLongPageHeader
Definition: xlog_internal.h:74
RecoveryTargetAction
char rp_name[MAXFNAMELEN]
unsigned short uint16
Definition: c.h:257
char * recoveryRestoreCommand
Definition: xlog.c:259
void(* rm_desc)(StringInfo buf, XLogReaderState *record)
static char * buf
Definition: pg_test_fsync.c:67
uint64 XLogSegNo
Definition: xlogdefs.h:34
struct XLogRecData XLogRecData
bool ArchiveRecoveryRequested
Definition: xlog.c:248
bool XLogArchiveIsBusy(const char *xlog)
Definition: xlogarchive.c:659
unsigned int uint32
Definition: c.h:258
TimeLineID xlp_tli
Definition: xlog_internal.h:40
XLogRecPtr xlp_pageaddr
Definition: xlog_internal.h:41
struct xl_restore_point xl_restore_point
void XLogArchiveForceDone(const char *xlog)
Definition: xlogarchive.c:564
#define MAXFNAMELEN
bool InArchiveRecovery
Definition: xlog.c:249
void(* rm_cleanup)(void)
bool XLogArchiveIsReady(const char *xlog)
Definition: xlogarchive.c:734
TimestampTz end_time
uint64 XLogRecPtr
Definition: xlogdefs.h:21
const RmgrData RmgrTable[]
Definition: rmgr.c:36
const char * rm_name
struct XLogRecData * next
bool RestoreArchivedFile(char *path, const char *xlogfname, const char *recovername, off_t expectedSize, bool cleanupEnabled)
Definition: xlogarchive.c:51
TimestampTz rp_time
TimeLineID ThisTimeLineID
XLogPageHeaderData std
Definition: xlog_internal.h:66
void GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli)
Definition: xlog.c:11226
void KeepFileRestoredFromArchive(char *path, char *xlogfname)
Definition: xlogarchive.c:428
struct XLogPageHeaderData XLogPageHeaderData
struct RmgrData RmgrData
void(* rm_startup)(void)