PostgreSQL Source Code  git master
lock.h
Go to the documentation of this file.
1 /*-------------------------------------------------------------------------
2  *
3  * lock.h
4  * POSTGRES low-level lock mechanism
5  *
6  *
7  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * src/include/storage/lock.h
11  *
12  *-------------------------------------------------------------------------
13  */
14 #ifndef LOCK_H_
15 #define LOCK_H_
16 
17 #ifdef FRONTEND
18 #error "lock.h may not be included from frontend code"
19 #endif
20 
21 #include "storage/backendid.h"
22 #include "storage/lockdefs.h"
23 #include "storage/lwlock.h"
24 #include "storage/shmem.h"
25 #include "utils/timestamp.h"
26 
27 /* struct PGPROC is declared in proc.h, but must forward-reference it */
28 typedef struct PGPROC PGPROC;
29 
30 typedef struct PROC_QUEUE
31 {
32  SHM_QUEUE links; /* head of list of PGPROC objects */
33  int size; /* number of entries in list */
34 } PROC_QUEUE;
35 
36 /* GUC variables */
37 extern int max_locks_per_xact;
38 
39 #ifdef LOCK_DEBUG
40 extern int Trace_lock_oidmin;
41 extern bool Trace_locks;
42 extern bool Trace_userlocks;
43 extern int Trace_lock_table;
44 extern bool Debug_deadlocks;
45 #endif /* LOCK_DEBUG */
46 
47 
48 /*
49  * Top-level transactions are identified by VirtualTransactionIDs comprising
50  * PGPROC fields backendId and lxid. For prepared transactions, the
51  * LocalTransactionId is an ordinary XID. These are guaranteed unique over
52  * the short term, but will be reused after a database restart or XID
53  * wraparound; hence they should never be stored on disk.
54  *
55  * Note that struct VirtualTransactionId can not be assumed to be atomically
56  * assignable as a whole. However, type LocalTransactionId is assumed to
57  * be atomically assignable, and the backend ID doesn't change often enough
58  * to be a problem, so we can fetch or assign the two fields separately.
59  * We deliberately refrain from using the struct within PGPROC, to prevent
60  * coding errors from trying to use struct assignment with it; instead use
61  * GET_VXID_FROM_PGPROC().
62  */
63 typedef struct
64 {
65  BackendId backendId; /* backendId from PGPROC */
66  LocalTransactionId localTransactionId; /* lxid from PGPROC */
68 
69 #define InvalidLocalTransactionId 0
70 #define LocalTransactionIdIsValid(lxid) ((lxid) != InvalidLocalTransactionId)
71 #define VirtualTransactionIdIsValid(vxid) \
72  (LocalTransactionIdIsValid((vxid).localTransactionId))
73 #define VirtualTransactionIdIsPreparedXact(vxid) \
74  ((vxid).backendId == InvalidBackendId)
75 #define VirtualTransactionIdEquals(vxid1, vxid2) \
76  ((vxid1).backendId == (vxid2).backendId && \
77  (vxid1).localTransactionId == (vxid2).localTransactionId)
78 #define SetInvalidVirtualTransactionId(vxid) \
79  ((vxid).backendId = InvalidBackendId, \
80  (vxid).localTransactionId = InvalidLocalTransactionId)
81 #define GET_VXID_FROM_PGPROC(vxid, proc) \
82  ((vxid).backendId = (proc).backendId, \
83  (vxid).localTransactionId = (proc).lxid)
84 
85 /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
86 #define MAX_LOCKMODES 10
87 
88 #define LOCKBIT_ON(lockmode) (1 << (lockmode))
89 #define LOCKBIT_OFF(lockmode) (~(1 << (lockmode)))
90 
91 
92 /*
93  * This data structure defines the locking semantics associated with a
94  * "lock method". The semantics specify the meaning of each lock mode
95  * (by defining which lock modes it conflicts with).
96  * All of this data is constant and is kept in const tables.
97  *
98  * numLockModes -- number of lock modes (READ,WRITE,etc) that
99  * are defined in this lock method. Must be less than MAX_LOCKMODES.
100  *
101  * conflictTab -- this is an array of bitmasks showing lock
102  * mode conflicts. conflictTab[i] is a mask with the j-th bit
103  * turned on if lock modes i and j conflict. Lock modes are
104  * numbered 1..numLockModes; conflictTab[0] is unused.
105  *
106  * lockModeNames -- ID strings for debug printouts.
107  *
108  * trace_flag -- pointer to GUC trace flag for this lock method. (The
109  * GUC variable is not constant, but we use "const" here to denote that
110  * it can't be changed through this reference.)
111  */
112 typedef struct LockMethodData
113 {
116  const char *const *lockModeNames;
117  const bool *trace_flag;
119 
120 typedef const LockMethodData *LockMethod;
121 
122 /*
123  * Lock methods are identified by LOCKMETHODID. (Despite the declaration as
124  * uint16, we are constrained to 256 lockmethods by the layout of LOCKTAG.)
125  */
127 
128 /* These identify the known lock methods */
129 #define DEFAULT_LOCKMETHOD 1
130 #define USER_LOCKMETHOD 2
131 
132 /*
133  * LOCKTAG is the key information needed to look up a LOCK item in the
134  * lock hashtable. A LOCKTAG value uniquely identifies a lockable object.
135  *
136  * The LockTagType enum defines the different kinds of objects we can lock.
137  * We can handle up to 256 different LockTagTypes.
138  */
139 typedef enum LockTagType
140 {
141  LOCKTAG_RELATION, /* whole relation */
142  LOCKTAG_RELATION_EXTEND, /* the right to extend a relation */
143  LOCKTAG_DATABASE_FROZEN_IDS, /* pg_database.datfrozenxid */
144  LOCKTAG_PAGE, /* one page of a relation */
145  LOCKTAG_TUPLE, /* one physical tuple */
146  LOCKTAG_TRANSACTION, /* transaction (for waiting for xact done) */
147  LOCKTAG_VIRTUALTRANSACTION, /* virtual transaction (ditto) */
148  LOCKTAG_SPECULATIVE_TOKEN, /* speculative insertion Xid and token */
149  LOCKTAG_OBJECT, /* non-relation database object */
150  LOCKTAG_USERLOCK, /* reserved for old contrib/userlock code */
151  LOCKTAG_ADVISORY /* advisory user locks */
152 } LockTagType;
153 
154 #define LOCKTAG_LAST_TYPE LOCKTAG_ADVISORY
155 
156 extern const char *const LockTagTypeNames[];
157 
158 /*
159  * The LOCKTAG struct is defined with malice aforethought to fit into 16
160  * bytes with no padding. Note that this would need adjustment if we were
161  * to widen Oid, BlockNumber, or TransactionId to more than 32 bits.
162  *
163  * We include lockmethodid in the locktag so that a single hash table in
164  * shared memory can store locks of different lockmethods.
165  */
166 typedef struct LOCKTAG
167 {
168  uint32 locktag_field1; /* a 32-bit ID field */
169  uint32 locktag_field2; /* a 32-bit ID field */
170  uint32 locktag_field3; /* a 32-bit ID field */
171  uint16 locktag_field4; /* a 16-bit ID field */
172  uint8 locktag_type; /* see enum LockTagType */
173  uint8 locktag_lockmethodid; /* lockmethod indicator */
174 } LOCKTAG;
175 
176 /*
177  * These macros define how we map logical IDs of lockable objects into
178  * the physical fields of LOCKTAG. Use these to set up LOCKTAG values,
179  * rather than accessing the fields directly. Note multiple eval of target!
180  */
181 
182 /* ID info for a relation is DB OID + REL OID; DB OID = 0 if shared */
183 #define SET_LOCKTAG_RELATION(locktag,dboid,reloid) \
184  ((locktag).locktag_field1 = (dboid), \
185  (locktag).locktag_field2 = (reloid), \
186  (locktag).locktag_field3 = 0, \
187  (locktag).locktag_field4 = 0, \
188  (locktag).locktag_type = LOCKTAG_RELATION, \
189  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
190 
191 /* same ID info as RELATION */
192 #define SET_LOCKTAG_RELATION_EXTEND(locktag,dboid,reloid) \
193  ((locktag).locktag_field1 = (dboid), \
194  (locktag).locktag_field2 = (reloid), \
195  (locktag).locktag_field3 = 0, \
196  (locktag).locktag_field4 = 0, \
197  (locktag).locktag_type = LOCKTAG_RELATION_EXTEND, \
198  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
199 
200 /* ID info for frozen IDs is DB OID */
201 #define SET_LOCKTAG_DATABASE_FROZEN_IDS(locktag,dboid) \
202  ((locktag).locktag_field1 = (dboid), \
203  (locktag).locktag_field2 = 0, \
204  (locktag).locktag_field3 = 0, \
205  (locktag).locktag_field4 = 0, \
206  (locktag).locktag_type = LOCKTAG_DATABASE_FROZEN_IDS, \
207  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
208 
209 /* ID info for a page is RELATION info + BlockNumber */
210 #define SET_LOCKTAG_PAGE(locktag,dboid,reloid,blocknum) \
211  ((locktag).locktag_field1 = (dboid), \
212  (locktag).locktag_field2 = (reloid), \
213  (locktag).locktag_field3 = (blocknum), \
214  (locktag).locktag_field4 = 0, \
215  (locktag).locktag_type = LOCKTAG_PAGE, \
216  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
217 
218 /* ID info for a tuple is PAGE info + OffsetNumber */
219 #define SET_LOCKTAG_TUPLE(locktag,dboid,reloid,blocknum,offnum) \
220  ((locktag).locktag_field1 = (dboid), \
221  (locktag).locktag_field2 = (reloid), \
222  (locktag).locktag_field3 = (blocknum), \
223  (locktag).locktag_field4 = (offnum), \
224  (locktag).locktag_type = LOCKTAG_TUPLE, \
225  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
226 
227 /* ID info for a transaction is its TransactionId */
228 #define SET_LOCKTAG_TRANSACTION(locktag,xid) \
229  ((locktag).locktag_field1 = (xid), \
230  (locktag).locktag_field2 = 0, \
231  (locktag).locktag_field3 = 0, \
232  (locktag).locktag_field4 = 0, \
233  (locktag).locktag_type = LOCKTAG_TRANSACTION, \
234  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
235 
236 /* ID info for a virtual transaction is its VirtualTransactionId */
237 #define SET_LOCKTAG_VIRTUALTRANSACTION(locktag,vxid) \
238  ((locktag).locktag_field1 = (vxid).backendId, \
239  (locktag).locktag_field2 = (vxid).localTransactionId, \
240  (locktag).locktag_field3 = 0, \
241  (locktag).locktag_field4 = 0, \
242  (locktag).locktag_type = LOCKTAG_VIRTUALTRANSACTION, \
243  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
244 
245 /*
246  * ID info for a speculative insert is TRANSACTION info +
247  * its speculative insert counter.
248  */
249 #define SET_LOCKTAG_SPECULATIVE_INSERTION(locktag,xid,token) \
250  ((locktag).locktag_field1 = (xid), \
251  (locktag).locktag_field2 = (token), \
252  (locktag).locktag_field3 = 0, \
253  (locktag).locktag_field4 = 0, \
254  (locktag).locktag_type = LOCKTAG_SPECULATIVE_TOKEN, \
255  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
256 
257 /*
258  * ID info for an object is DB OID + CLASS OID + OBJECT OID + SUBID
259  *
260  * Note: object ID has same representation as in pg_depend and
261  * pg_description, but notice that we are constraining SUBID to 16 bits.
262  * Also, we use DB OID = 0 for shared objects such as tablespaces.
263  */
264 #define SET_LOCKTAG_OBJECT(locktag,dboid,classoid,objoid,objsubid) \
265  ((locktag).locktag_field1 = (dboid), \
266  (locktag).locktag_field2 = (classoid), \
267  (locktag).locktag_field3 = (objoid), \
268  (locktag).locktag_field4 = (objsubid), \
269  (locktag).locktag_type = LOCKTAG_OBJECT, \
270  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
271 
272 #define SET_LOCKTAG_ADVISORY(locktag,id1,id2,id3,id4) \
273  ((locktag).locktag_field1 = (id1), \
274  (locktag).locktag_field2 = (id2), \
275  (locktag).locktag_field3 = (id3), \
276  (locktag).locktag_field4 = (id4), \
277  (locktag).locktag_type = LOCKTAG_ADVISORY, \
278  (locktag).locktag_lockmethodid = USER_LOCKMETHOD)
279 
280 
281 /*
282  * Per-locked-object lock information:
283  *
284  * tag -- uniquely identifies the object being locked
285  * grantMask -- bitmask for all lock types currently granted on this object.
286  * waitMask -- bitmask for all lock types currently awaited on this object.
287  * procLocks -- list of PROCLOCK objects for this lock.
288  * waitProcs -- queue of processes waiting for this lock.
289  * requested -- count of each lock type currently requested on the lock
290  * (includes requests already granted!!).
291  * nRequested -- total requested locks of all types.
292  * granted -- count of each lock type currently granted on the lock.
293  * nGranted -- total granted locks of all types.
294  *
295  * Note: these counts count 1 for each backend. Internally to a backend,
296  * there may be multiple grabs on a particular lock, but this is not reflected
297  * into shared memory.
298  */
299 typedef struct LOCK
300 {
301  /* hash key */
302  LOCKTAG tag; /* unique identifier of lockable object */
303 
304  /* data */
305  LOCKMASK grantMask; /* bitmask for lock types already granted */
306  LOCKMASK waitMask; /* bitmask for lock types awaited */
307  SHM_QUEUE procLocks; /* list of PROCLOCK objects assoc. with lock */
308  PROC_QUEUE waitProcs; /* list of PGPROC objects waiting on lock */
309  int requested[MAX_LOCKMODES]; /* counts of requested locks */
310  int nRequested; /* total of requested[] array */
311  int granted[MAX_LOCKMODES]; /* counts of granted locks */
312  int nGranted; /* total of granted[] array */
313 } LOCK;
314 
315 #define LOCK_LOCKMETHOD(lock) ((LOCKMETHODID) (lock).tag.locktag_lockmethodid)
316 #define LOCK_LOCKTAG(lock) ((LockTagType) (lock).tag.locktag_type)
317 
318 
319 /*
320  * We may have several different backends holding or awaiting locks
321  * on the same lockable object. We need to store some per-holder/waiter
322  * information for each such holder (or would-be holder). This is kept in
323  * a PROCLOCK struct.
324  *
325  * PROCLOCKTAG is the key information needed to look up a PROCLOCK item in the
326  * proclock hashtable. A PROCLOCKTAG value uniquely identifies the combination
327  * of a lockable object and a holder/waiter for that object. (We can use
328  * pointers here because the PROCLOCKTAG need only be unique for the lifespan
329  * of the PROCLOCK, and it will never outlive the lock or the proc.)
330  *
331  * Internally to a backend, it is possible for the same lock to be held
332  * for different purposes: the backend tracks transaction locks separately
333  * from session locks. However, this is not reflected in the shared-memory
334  * state: we only track which backend(s) hold the lock. This is OK since a
335  * backend can never block itself.
336  *
337  * The holdMask field shows the already-granted locks represented by this
338  * proclock. Note that there will be a proclock object, possibly with
339  * zero holdMask, for any lock that the process is currently waiting on.
340  * Otherwise, proclock objects whose holdMasks are zero are recycled
341  * as soon as convenient.
342  *
343  * releaseMask is workspace for LockReleaseAll(): it shows the locks due
344  * to be released during the current call. This must only be examined or
345  * set by the backend owning the PROCLOCK.
346  *
347  * Each PROCLOCK object is linked into lists for both the associated LOCK
348  * object and the owning PGPROC object. Note that the PROCLOCK is entered
349  * into these lists as soon as it is created, even if no lock has yet been
350  * granted. A PGPROC that is waiting for a lock to be granted will also be
351  * linked into the lock's waitProcs queue.
352  */
353 typedef struct PROCLOCKTAG
354 {
355  /* NB: we assume this struct contains no padding! */
356  LOCK *myLock; /* link to per-lockable-object information */
357  PGPROC *myProc; /* link to PGPROC of owning backend */
358 } PROCLOCKTAG;
359 
360 typedef struct PROCLOCK
361 {
362  /* tag */
363  PROCLOCKTAG tag; /* unique identifier of proclock object */
364 
365  /* data */
366  PGPROC *groupLeader; /* proc's lock group leader, or proc itself */
367  LOCKMASK holdMask; /* bitmask for lock types currently held */
368  LOCKMASK releaseMask; /* bitmask for lock types to be released */
369  SHM_QUEUE lockLink; /* list link in LOCK's list of proclocks */
370  SHM_QUEUE procLink; /* list link in PGPROC's list of proclocks */
371 } PROCLOCK;
372 
373 #define PROCLOCK_LOCKMETHOD(proclock) \
374  LOCK_LOCKMETHOD(*((proclock).tag.myLock))
375 
376 /*
377  * Each backend also maintains a local hash table with information about each
378  * lock it is currently interested in. In particular the local table counts
379  * the number of times that lock has been acquired. This allows multiple
380  * requests for the same lock to be executed without additional accesses to
381  * shared memory. We also track the number of lock acquisitions per
382  * ResourceOwner, so that we can release just those locks belonging to a
383  * particular ResourceOwner.
384  *
385  * When holding a lock taken "normally", the lock and proclock fields always
386  * point to the associated objects in shared memory. However, if we acquired
387  * the lock via the fast-path mechanism, the lock and proclock fields are set
388  * to NULL, since there probably aren't any such objects in shared memory.
389  * (If the lock later gets promoted to normal representation, we may eventually
390  * update our locallock's lock/proclock fields after finding the shared
391  * objects.)
392  *
393  * Caution: a locallock object can be left over from a failed lock acquisition
394  * attempt. In this case its lock/proclock fields are untrustworthy, since
395  * the shared lock object is neither held nor awaited, and hence is available
396  * to be reclaimed. If nLocks > 0 then these pointers must either be valid or
397  * NULL, but when nLocks == 0 they should be considered garbage.
398  */
399 typedef struct LOCALLOCKTAG
400 {
401  LOCKTAG lock; /* identifies the lockable object */
402  LOCKMODE mode; /* lock mode for this table entry */
403 } LOCALLOCKTAG;
404 
405 typedef struct LOCALLOCKOWNER
406 {
407  /*
408  * Note: if owner is NULL then the lock is held on behalf of the session;
409  * otherwise it is held on behalf of my current transaction.
410  *
411  * Must use a forward struct reference to avoid circularity.
412  */
414  int64 nLocks; /* # of times held by this owner */
416 
417 typedef struct LOCALLOCK
418 {
419  /* tag */
420  LOCALLOCKTAG tag; /* unique identifier of locallock entry */
421 
422  /* data */
423  uint32 hashcode; /* copy of LOCKTAG's hash value */
424  LOCK *lock; /* associated LOCK object, if any */
425  PROCLOCK *proclock; /* associated PROCLOCK object, if any */
426  int64 nLocks; /* total number of times lock is held */
427  int numLockOwners; /* # of relevant ResourceOwners */
428  int maxLockOwners; /* allocated size of array */
429  LOCALLOCKOWNER *lockOwners; /* dynamically resizable array */
430  bool holdsStrongLockCount; /* bumped FastPathStrongRelationLocks */
431  bool lockCleared; /* we read all sinval msgs for lock */
432 } LOCALLOCK;
433 
434 #define LOCALLOCK_LOCKMETHOD(llock) ((llock).tag.lock.locktag_lockmethodid)
435 #define LOCALLOCK_LOCKTAG(llock) ((LockTagType) (llock).tag.lock.locktag_type)
436 
437 
438 /*
439  * These structures hold information passed from lmgr internals to the lock
440  * listing user-level functions (in lockfuncs.c).
441  */
442 
443 typedef struct LockInstanceData
444 {
445  LOCKTAG locktag; /* tag for locked object */
446  LOCKMASK holdMask; /* locks held by this PGPROC */
447  LOCKMODE waitLockMode; /* lock awaited by this PGPROC, if any */
448  BackendId backend; /* backend ID of this PGPROC */
449  LocalTransactionId lxid; /* local transaction ID of this PGPROC */
450  TimestampTz waitStart; /* time at which this PGPROC started waiting
451  * for lock */
452  int pid; /* pid of this PGPROC */
453  int leaderPid; /* pid of group leader; = pid if no group */
454  bool fastpath; /* taken via fastpath? */
456 
457 typedef struct LockData
458 {
459  int nelements; /* The length of the array */
460  LockInstanceData *locks; /* Array of per-PROCLOCK information */
461 } LockData;
462 
463 typedef struct BlockedProcData
464 {
465  int pid; /* pid of a blocked PGPROC */
466  /* Per-PROCLOCK information about PROCLOCKs of the lock the pid awaits */
467  /* (these fields refer to indexes in BlockedProcsData.locks[]) */
468  int first_lock; /* index of first relevant LockInstanceData */
469  int num_locks; /* number of relevant LockInstanceDatas */
470  /* PIDs of PGPROCs that are ahead of "pid" in the lock's wait queue */
471  /* (these fields refer to indexes in BlockedProcsData.waiter_pids[]) */
472  int first_waiter; /* index of first preceding waiter */
473  int num_waiters; /* number of preceding waiters */
475 
476 typedef struct BlockedProcsData
477 {
478  BlockedProcData *procs; /* Array of per-blocked-proc information */
479  LockInstanceData *locks; /* Array of per-PROCLOCK information */
480  int *waiter_pids; /* Array of PIDs of other blocked PGPROCs */
481  int nprocs; /* # of valid entries in procs[] array */
482  int maxprocs; /* Allocated length of procs[] array */
483  int nlocks; /* # of valid entries in locks[] array */
484  int maxlocks; /* Allocated length of locks[] array */
485  int npids; /* # of valid entries in waiter_pids[] array */
486  int maxpids; /* Allocated length of waiter_pids[] array */
488 
489 
490 /* Result codes for LockAcquire() */
491 typedef enum
492 {
493  LOCKACQUIRE_NOT_AVAIL, /* lock not available, and dontWait=true */
494  LOCKACQUIRE_OK, /* lock successfully acquired */
495  LOCKACQUIRE_ALREADY_HELD, /* incremented count for lock already held */
496  LOCKACQUIRE_ALREADY_CLEAR /* incremented count for lock already clear */
498 
499 /* Deadlock states identified by DeadLockCheck() */
500 typedef enum
501 {
502  DS_NOT_YET_CHECKED, /* no deadlock check has run yet */
503  DS_NO_DEADLOCK, /* no deadlock detected */
504  DS_SOFT_DEADLOCK, /* deadlock avoided by queue rearrangement */
505  DS_HARD_DEADLOCK, /* deadlock, no way out but ERROR */
506  DS_BLOCKED_BY_AUTOVACUUM /* no deadlock; queue blocked by autovacuum
507  * worker */
508 } DeadLockState;
509 
510 /*
511  * The lockmgr's shared hash tables are partitioned to reduce contention.
512  * To determine which partition a given locktag belongs to, compute the tag's
513  * hash code with LockTagHashCode(), then apply one of these macros.
514  * NB: NUM_LOCK_PARTITIONS must be a power of 2!
515  */
516 #define LockHashPartition(hashcode) \
517  ((hashcode) % NUM_LOCK_PARTITIONS)
518 #define LockHashPartitionLock(hashcode) \
519  (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + \
520  LockHashPartition(hashcode)].lock)
521 #define LockHashPartitionLockByIndex(i) \
522  (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + (i)].lock)
523 
524 /*
525  * The deadlock detector needs to be able to access lockGroupLeader and
526  * related fields in the PGPROC, so we arrange for those fields to be protected
527  * by one of the lock hash partition locks. Since the deadlock detector
528  * acquires all such locks anyway, this makes it safe for it to access these
529  * fields without doing anything extra. To avoid contention as much as
530  * possible, we map different PGPROCs to different partition locks. The lock
531  * used for a given lock group is determined by the group leader's pgprocno.
532  */
533 #define LockHashPartitionLockByProc(leader_pgproc) \
534  LockHashPartitionLock((leader_pgproc)->pgprocno)
535 
536 /*
537  * function prototypes
538  */
539 extern void InitLocks(void);
540 extern LockMethod GetLocksMethodTable(const LOCK *lock);
541 extern LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag);
542 extern uint32 LockTagHashCode(const LOCKTAG *locktag);
543 extern bool DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2);
544 extern LockAcquireResult LockAcquire(const LOCKTAG *locktag,
545  LOCKMODE lockmode,
546  bool sessionLock,
547  bool dontWait);
548 extern LockAcquireResult LockAcquireExtended(const LOCKTAG *locktag,
549  LOCKMODE lockmode,
550  bool sessionLock,
551  bool dontWait,
552  bool reportMemoryError,
553  LOCALLOCK **locallockp);
554 extern void AbortStrongLockAcquire(void);
555 extern void MarkLockClear(LOCALLOCK *locallock);
556 extern bool LockRelease(const LOCKTAG *locktag,
557  LOCKMODE lockmode, bool sessionLock);
558 extern void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks);
559 extern void LockReleaseSession(LOCKMETHODID lockmethodid);
560 extern void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks);
561 extern void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks);
562 extern bool LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode);
563 #ifdef USE_ASSERT_CHECKING
564 extern HTAB *GetLockMethodLocalHash(void);
565 #endif
566 extern bool LockHasWaiters(const LOCKTAG *locktag,
567  LOCKMODE lockmode, bool sessionLock);
568 extern VirtualTransactionId *GetLockConflicts(const LOCKTAG *locktag,
569  LOCKMODE lockmode, int *countp);
570 extern void AtPrepare_Locks(void);
571 extern void PostPrepare_Locks(TransactionId xid);
572 extern bool LockCheckConflicts(LockMethod lockMethodTable,
573  LOCKMODE lockmode,
574  LOCK *lock, PROCLOCK *proclock);
575 extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode);
576 extern void GrantAwaitedLock(void);
577 extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode);
578 extern Size LockShmemSize(void);
579 extern LockData *GetLockStatusData(void);
580 extern BlockedProcsData *GetBlockerStatusData(int blocked_pid);
581 
582 extern xl_standby_lock *GetRunningTransactionLocks(int *nlocks);
583 extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode);
584 
585 extern void lock_twophase_recover(TransactionId xid, uint16 info,
586  void *recdata, uint32 len);
587 extern void lock_twophase_postcommit(TransactionId xid, uint16 info,
588  void *recdata, uint32 len);
589 extern void lock_twophase_postabort(TransactionId xid, uint16 info,
590  void *recdata, uint32 len);
592  void *recdata, uint32 len);
593 
594 extern DeadLockState DeadLockCheck(PGPROC *proc);
595 extern PGPROC *GetBlockingAutoVacuumPgproc(void);
596 extern void DeadLockReport(void) pg_attribute_noreturn();
597 extern void RememberSimpleDeadLock(PGPROC *proc1,
598  LOCKMODE lockmode,
599  LOCK *lock,
600  PGPROC *proc2);
601 extern void InitDeadLockChecking(void);
602 
603 extern int LockWaiterCount(const LOCKTAG *locktag);
604 
605 #ifdef LOCK_DEBUG
606 extern void DumpLocks(PGPROC *proc);
607 extern void DumpAllLocks(void);
608 #endif
609 
610 /* Lock a VXID (used to wait for a transaction to finish) */
612 extern void VirtualXactLockTableCleanup(void);
613 extern bool VirtualXactLock(VirtualTransactionId vxid, bool wait);
614 
615 #endif /* LOCK_H_ */
struct BlockedProcData BlockedProcData
const char *const LockTagTypeNames[]
Definition: lockfuncs.c:29
PROCLOCKTAG tag
Definition: lock.h:363
static PgChecksumMode mode
Definition: pg_checksums.c:65
#define pg_attribute_noreturn()
Definition: c.h:179
uint32 hashcode
Definition: lock.h:423
void MarkLockClear(LOCALLOCK *locallock)
Definition: lock.c:1799
Size LockShmemSize(void)
Definition: lock.c:3605
void VirtualXactLockTableInsert(VirtualTransactionId vxid)
Definition: lock.c:4472
LOCALLOCKTAG tag
Definition: lock.h:420
bool holdsStrongLockCount
Definition: lock.h:430
void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
Definition: lock.c:1918
int * waiter_pids
Definition: lock.h:480
void AbortStrongLockAcquire(void)
Definition: lock.c:1757
int numLockOwners
Definition: lock.h:427
LockInstanceData * locks
Definition: lock.h:460
LOCKTAG lock
Definition: lock.h:401
uint32 TransactionId
Definition: c.h:587
void lock_twophase_postcommit(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4422
int LOCKMODE
Definition: lockdefs.h:26
int first_lock
Definition: lock.h:468
LOCKMODE mode
Definition: lock.h:402
void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
Definition: lock.c:2484
PROCLOCK * proclock
Definition: lock.h:425
int nRequested
Definition: lock.h:310
SHM_QUEUE links
Definition: lock.h:32
int64 TimestampTz
Definition: timestamp.h:39
int num_waiters
Definition: lock.h:473
LOCKMASK holdMask
Definition: lock.h:367
int64 nLocks
Definition: lock.h:414
LockAcquireResult LockAcquireExtended(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait, bool reportMemoryError, LOCALLOCK **locallockp)
Definition: lock.c:771
bool fastpath
Definition: lock.h:454
LockMethod GetLocksMethodTable(const LOCK *lock)
Definition: lock.c:487
struct LOCALLOCKOWNER LOCALLOCKOWNER
LOCKTAG tag
Definition: lock.h:302
void PostPrepare_Locks(TransactionId xid)
Definition: lock.c:3413
unsigned char uint8
Definition: c.h:439
Definition: lock.h:166
const LOCKMASK * conflictTab
Definition: lock.h:115
int LockWaiterCount(const LOCKTAG *locktag)
Definition: lock.c:4653
SHM_QUEUE lockLink
Definition: lock.h:369
void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
Definition: lock.c:2579
LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag)
Definition: lock.c:499
BlockedProcData * procs
Definition: lock.h:478
Definition: lock.h:457
LocalTransactionId localTransactionId
Definition: lock.h:66
struct LOCALLOCKTAG LOCALLOCKTAG
LOCKTAG locktag
Definition: lock.h:445
LOCKMODE waitLockMode
Definition: lock.h:447
int maxLockOwners
Definition: lock.h:428
int nGranted
Definition: lock.h:312
void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
Definition: lock.c:2180
void DeadLockReport(void) pg_attribute_noreturn()
Definition: deadlock.c:1090
int num_locks
Definition: lock.h:469
int max_locks_per_xact
Definition: lock.c:55
PROC_QUEUE waitProcs
Definition: lock.h:308
void InitLocks(void)
Definition: lock.c:405
uint16 locktag_field4
Definition: lock.h:171
BlockedProcsData * GetBlockerStatusData(int blocked_pid)
Definition: lock.c:3834
int leaderPid
Definition: lock.h:453
Definition: dynahash.c:219
struct LOCALLOCK LOCALLOCK
unsigned short uint16
Definition: c.h:440
struct BlockedProcsData BlockedProcsData
bool LockCheckConflicts(LockMethod lockMethodTable, LOCKMODE lockmode, LOCK *lock, PROCLOCK *proclock)
Definition: lock.c:1420
void lock_twophase_postabort(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4448
LockAcquireResult LockAcquire(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
Definition: lock.c:747
void VirtualXactLockTableCleanup(void)
Definition: lock.c:4495
const char * GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
Definition: lock.c:4096
uint32 locktag_field2
Definition: lock.h:169
unsigned int uint32
Definition: c.h:441
bool LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode)
Definition: lock.c:598
Definition: lock.h:299
uint32 LocalTransactionId
Definition: c.h:589
xl_standby_lock * GetRunningTransactionLocks(int *nlocks)
Definition: lock.c:4014
struct PROCLOCK PROCLOCK
LOCKMASK waitMask
Definition: lock.h:306
int maxlocks
Definition: lock.h:484
uint16 LOCKMETHODID
Definition: lock.h:126
SHM_QUEUE procLocks
Definition: lock.h:307
struct LOCKTAG LOCKTAG
TimestampTz waitStart
Definition: lock.h:450
int nelements
Definition: lock.h:459
#define MAX_LOCKMODES
Definition: lock.h:86
SHM_QUEUE procLink
Definition: lock.h:370
LockInstanceData * locks
Definition: lock.h:479
struct PROCLOCKTAG PROCLOCKTAG
const LockMethodData * LockMethod
Definition: lock.h:120
BackendId backend
Definition: lock.h:448
int BackendId
Definition: backendid.h:21
bool LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:1975
bool LockHasWaiters(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:634
void RememberSimpleDeadLock(PGPROC *proc1, LOCKMODE lockmode, LOCK *lock, PGPROC *proc2)
Definition: deadlock.c:1162
DeadLockState DeadLockCheck(PGPROC *proc)
Definition: deadlock.c:217
struct LOCK LOCK
void lock_twophase_recover(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4209
int first_waiter
Definition: lock.h:472
void GrantAwaitedLock(void)
Definition: lock.c:1786
bool DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
Definition: lock.c:583
uint8 locktag_type
Definition: lock.h:172
DeadLockState
Definition: lock.h:500
LocalTransactionId lxid
Definition: lock.h:449
BackendId backendId
Definition: lock.h:65
size_t Size
Definition: c.h:540
bool VirtualXactLock(VirtualTransactionId vxid, bool wait)
Definition: lock.c:4542
LOCALLOCKOWNER * lockOwners
Definition: lock.h:429
LOCK * lock
Definition: lock.h:424
int LOCKMASK
Definition: lockdefs.h:25
struct LockMethodData LockMethodData
LOCKMASK holdMask
Definition: lock.h:446
uint8 locktag_lockmethodid
Definition: lock.h:173
PGPROC * myProc
Definition: lock.h:357
LOCKMASK grantMask
Definition: lock.h:305
Definition: lock.h:360
int64 nLocks
Definition: lock.h:426
struct PROC_QUEUE PROC_QUEUE
LockAcquireResult
Definition: lock.h:491
void InitDeadLockChecking(void)
Definition: deadlock.c:143
struct LockInstanceData LockInstanceData
const bool * trace_flag
Definition: lock.h:117
LockData * GetLockStatusData(void)
Definition: lock.c:3642
int size
Definition: lock.h:33
LOCK * myLock
Definition: lock.h:356
LockTagType
Definition: lock.h:139
struct ResourceOwnerData * owner
Definition: lock.h:413
void lock_twophase_standby_recover(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4390
struct LockData LockData
VirtualTransactionId * GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
Definition: lock.c:2910
PGPROC * GetBlockingAutoVacuumPgproc(void)
Definition: deadlock.c:293
void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
Definition: lock.c:1555
uint32 locktag_field1
Definition: lock.h:168
Definition: proc.h:121
uint32 LockTagHashCode(const LOCKTAG *locktag)
Definition: lock.c:517
uint32 locktag_field3
Definition: lock.h:170
void AtPrepare_Locks(void)
Definition: lock.c:3317
bool lockCleared
Definition: lock.h:431
const char *const * lockModeNames
Definition: lock.h:116
PGPROC * groupLeader
Definition: lock.h:366
void LockReleaseSession(LOCKMETHODID lockmethodid)
Definition: lock.c:2454
int numLockModes
Definition: lock.h:114
int maxprocs
Definition: lock.h:482
LOCKMASK releaseMask
Definition: lock.h:368