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lock.h
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1 /*-------------------------------------------------------------------------
2  *
3  * lock.h
4  * POSTGRES low-level lock mechanism
5  *
6  *
7  * Portions Copyright (c) 1996-2023, 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 "lib/ilist.h"
22 #include "storage/backendid.h"
23 #include "storage/lockdefs.h"
24 #include "storage/lwlock.h"
25 #include "storage/shmem.h"
26 #include "utils/timestamp.h"
27 
28 /* struct PGPROC is declared in proc.h, but must forward-reference it */
29 typedef struct PGPROC PGPROC;
30 
31 /* GUC variables */
33 
34 #ifdef LOCK_DEBUG
35 extern PGDLLIMPORT int Trace_lock_oidmin;
36 extern PGDLLIMPORT bool Trace_locks;
37 extern PGDLLIMPORT bool Trace_userlocks;
38 extern PGDLLIMPORT int Trace_lock_table;
39 extern PGDLLIMPORT bool Debug_deadlocks;
40 #endif /* LOCK_DEBUG */
41 
42 
43 /*
44  * Top-level transactions are identified by VirtualTransactionIDs comprising
45  * PGPROC fields backendId and lxid. For recovered prepared transactions, the
46  * LocalTransactionId is an ordinary XID; LOCKTAG_VIRTUALTRANSACTION never
47  * refers to that kind. These are guaranteed unique over the short term, but
48  * will be reused after a database restart or XID wraparound; hence they
49  * should never be stored on disk.
50  *
51  * Note that struct VirtualTransactionId can not be assumed to be atomically
52  * assignable as a whole. However, type LocalTransactionId is assumed to
53  * be atomically assignable, and the backend ID doesn't change often enough
54  * to be a problem, so we can fetch or assign the two fields separately.
55  * We deliberately refrain from using the struct within PGPROC, to prevent
56  * coding errors from trying to use struct assignment with it; instead use
57  * GET_VXID_FROM_PGPROC().
58  */
59 typedef struct
60 {
61  BackendId backendId; /* backendId from PGPROC */
62  LocalTransactionId localTransactionId; /* lxid from PGPROC */
64 
65 #define InvalidLocalTransactionId 0
66 #define LocalTransactionIdIsValid(lxid) ((lxid) != InvalidLocalTransactionId)
67 #define VirtualTransactionIdIsValid(vxid) \
68  (LocalTransactionIdIsValid((vxid).localTransactionId))
69 #define VirtualTransactionIdIsRecoveredPreparedXact(vxid) \
70  ((vxid).backendId == InvalidBackendId)
71 #define VirtualTransactionIdEquals(vxid1, vxid2) \
72  ((vxid1).backendId == (vxid2).backendId && \
73  (vxid1).localTransactionId == (vxid2).localTransactionId)
74 #define SetInvalidVirtualTransactionId(vxid) \
75  ((vxid).backendId = InvalidBackendId, \
76  (vxid).localTransactionId = InvalidLocalTransactionId)
77 #define GET_VXID_FROM_PGPROC(vxid, proc) \
78  ((vxid).backendId = (proc).backendId, \
79  (vxid).localTransactionId = (proc).lxid)
80 
81 /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
82 #define MAX_LOCKMODES 10
83 
84 #define LOCKBIT_ON(lockmode) (1 << (lockmode))
85 #define LOCKBIT_OFF(lockmode) (~(1 << (lockmode)))
86 
87 
88 /*
89  * This data structure defines the locking semantics associated with a
90  * "lock method". The semantics specify the meaning of each lock mode
91  * (by defining which lock modes it conflicts with).
92  * All of this data is constant and is kept in const tables.
93  *
94  * numLockModes -- number of lock modes (READ,WRITE,etc) that
95  * are defined in this lock method. Must be less than MAX_LOCKMODES.
96  *
97  * conflictTab -- this is an array of bitmasks showing lock
98  * mode conflicts. conflictTab[i] is a mask with the j-th bit
99  * turned on if lock modes i and j conflict. Lock modes are
100  * numbered 1..numLockModes; conflictTab[0] is unused.
101  *
102  * lockModeNames -- ID strings for debug printouts.
103  *
104  * trace_flag -- pointer to GUC trace flag for this lock method. (The
105  * GUC variable is not constant, but we use "const" here to denote that
106  * it can't be changed through this reference.)
107  */
108 typedef struct LockMethodData
109 {
112  const char *const *lockModeNames;
113  const bool *trace_flag;
115 
116 typedef const LockMethodData *LockMethod;
117 
118 /*
119  * Lock methods are identified by LOCKMETHODID. (Despite the declaration as
120  * uint16, we are constrained to 256 lockmethods by the layout of LOCKTAG.)
121  */
123 
124 /* These identify the known lock methods */
125 #define DEFAULT_LOCKMETHOD 1
126 #define USER_LOCKMETHOD 2
127 
128 /*
129  * LOCKTAG is the key information needed to look up a LOCK item in the
130  * lock hashtable. A LOCKTAG value uniquely identifies a lockable object.
131  *
132  * The LockTagType enum defines the different kinds of objects we can lock.
133  * We can handle up to 256 different LockTagTypes.
134  */
135 typedef enum LockTagType
136 {
137  LOCKTAG_RELATION, /* whole relation */
138  LOCKTAG_RELATION_EXTEND, /* the right to extend a relation */
139  LOCKTAG_DATABASE_FROZEN_IDS, /* pg_database.datfrozenxid */
140  LOCKTAG_PAGE, /* one page of a relation */
141  LOCKTAG_TUPLE, /* one physical tuple */
142  LOCKTAG_TRANSACTION, /* transaction (for waiting for xact done) */
143  LOCKTAG_VIRTUALTRANSACTION, /* virtual transaction (ditto) */
144  LOCKTAG_SPECULATIVE_TOKEN, /* speculative insertion Xid and token */
145  LOCKTAG_OBJECT, /* non-relation database object */
146  LOCKTAG_USERLOCK, /* reserved for old contrib/userlock code */
147  LOCKTAG_ADVISORY, /* advisory user locks */
148  LOCKTAG_APPLY_TRANSACTION /* transaction being applied on a logical
149  * replication subscriber */
151 
152 #define LOCKTAG_LAST_TYPE LOCKTAG_APPLY_TRANSACTION
153 
154 extern PGDLLIMPORT const char *const LockTagTypeNames[];
155 
156 /*
157  * The LOCKTAG struct is defined with malice aforethought to fit into 16
158  * bytes with no padding. Note that this would need adjustment if we were
159  * to widen Oid, BlockNumber, or TransactionId to more than 32 bits.
160  *
161  * We include lockmethodid in the locktag so that a single hash table in
162  * shared memory can store locks of different lockmethods.
163  */
164 typedef struct LOCKTAG
165 {
166  uint32 locktag_field1; /* a 32-bit ID field */
167  uint32 locktag_field2; /* a 32-bit ID field */
168  uint32 locktag_field3; /* a 32-bit ID field */
169  uint16 locktag_field4; /* a 16-bit ID field */
170  uint8 locktag_type; /* see enum LockTagType */
171  uint8 locktag_lockmethodid; /* lockmethod indicator */
173 
174 /*
175  * These macros define how we map logical IDs of lockable objects into
176  * the physical fields of LOCKTAG. Use these to set up LOCKTAG values,
177  * rather than accessing the fields directly. Note multiple eval of target!
178  */
179 
180 /* ID info for a relation is DB OID + REL OID; DB OID = 0 if shared */
181 #define SET_LOCKTAG_RELATION(locktag,dboid,reloid) \
182  ((locktag).locktag_field1 = (dboid), \
183  (locktag).locktag_field2 = (reloid), \
184  (locktag).locktag_field3 = 0, \
185  (locktag).locktag_field4 = 0, \
186  (locktag).locktag_type = LOCKTAG_RELATION, \
187  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
188 
189 /* same ID info as RELATION */
190 #define SET_LOCKTAG_RELATION_EXTEND(locktag,dboid,reloid) \
191  ((locktag).locktag_field1 = (dboid), \
192  (locktag).locktag_field2 = (reloid), \
193  (locktag).locktag_field3 = 0, \
194  (locktag).locktag_field4 = 0, \
195  (locktag).locktag_type = LOCKTAG_RELATION_EXTEND, \
196  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
197 
198 /* ID info for frozen IDs is DB OID */
199 #define SET_LOCKTAG_DATABASE_FROZEN_IDS(locktag,dboid) \
200  ((locktag).locktag_field1 = (dboid), \
201  (locktag).locktag_field2 = 0, \
202  (locktag).locktag_field3 = 0, \
203  (locktag).locktag_field4 = 0, \
204  (locktag).locktag_type = LOCKTAG_DATABASE_FROZEN_IDS, \
205  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
206 
207 /* ID info for a page is RELATION info + BlockNumber */
208 #define SET_LOCKTAG_PAGE(locktag,dboid,reloid,blocknum) \
209  ((locktag).locktag_field1 = (dboid), \
210  (locktag).locktag_field2 = (reloid), \
211  (locktag).locktag_field3 = (blocknum), \
212  (locktag).locktag_field4 = 0, \
213  (locktag).locktag_type = LOCKTAG_PAGE, \
214  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
215 
216 /* ID info for a tuple is PAGE info + OffsetNumber */
217 #define SET_LOCKTAG_TUPLE(locktag,dboid,reloid,blocknum,offnum) \
218  ((locktag).locktag_field1 = (dboid), \
219  (locktag).locktag_field2 = (reloid), \
220  (locktag).locktag_field3 = (blocknum), \
221  (locktag).locktag_field4 = (offnum), \
222  (locktag).locktag_type = LOCKTAG_TUPLE, \
223  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
224 
225 /* ID info for a transaction is its TransactionId */
226 #define SET_LOCKTAG_TRANSACTION(locktag,xid) \
227  ((locktag).locktag_field1 = (xid), \
228  (locktag).locktag_field2 = 0, \
229  (locktag).locktag_field3 = 0, \
230  (locktag).locktag_field4 = 0, \
231  (locktag).locktag_type = LOCKTAG_TRANSACTION, \
232  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
233 
234 /* ID info for a virtual transaction is its VirtualTransactionId */
235 #define SET_LOCKTAG_VIRTUALTRANSACTION(locktag,vxid) \
236  ((locktag).locktag_field1 = (vxid).backendId, \
237  (locktag).locktag_field2 = (vxid).localTransactionId, \
238  (locktag).locktag_field3 = 0, \
239  (locktag).locktag_field4 = 0, \
240  (locktag).locktag_type = LOCKTAG_VIRTUALTRANSACTION, \
241  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
242 
243 /*
244  * ID info for a speculative insert is TRANSACTION info +
245  * its speculative insert counter.
246  */
247 #define SET_LOCKTAG_SPECULATIVE_INSERTION(locktag,xid,token) \
248  ((locktag).locktag_field1 = (xid), \
249  (locktag).locktag_field2 = (token), \
250  (locktag).locktag_field3 = 0, \
251  (locktag).locktag_field4 = 0, \
252  (locktag).locktag_type = LOCKTAG_SPECULATIVE_TOKEN, \
253  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
254 
255 /*
256  * ID info for an object is DB OID + CLASS OID + OBJECT OID + SUBID
257  *
258  * Note: object ID has same representation as in pg_depend and
259  * pg_description, but notice that we are constraining SUBID to 16 bits.
260  * Also, we use DB OID = 0 for shared objects such as tablespaces.
261  */
262 #define SET_LOCKTAG_OBJECT(locktag,dboid,classoid,objoid,objsubid) \
263  ((locktag).locktag_field1 = (dboid), \
264  (locktag).locktag_field2 = (classoid), \
265  (locktag).locktag_field3 = (objoid), \
266  (locktag).locktag_field4 = (objsubid), \
267  (locktag).locktag_type = LOCKTAG_OBJECT, \
268  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
269 
270 #define SET_LOCKTAG_ADVISORY(locktag,id1,id2,id3,id4) \
271  ((locktag).locktag_field1 = (id1), \
272  (locktag).locktag_field2 = (id2), \
273  (locktag).locktag_field3 = (id3), \
274  (locktag).locktag_field4 = (id4), \
275  (locktag).locktag_type = LOCKTAG_ADVISORY, \
276  (locktag).locktag_lockmethodid = USER_LOCKMETHOD)
277 
278 /*
279  * ID info for a remote transaction on a logical replication subscriber is: DB
280  * OID + SUBSCRIPTION OID + TRANSACTION ID + OBJID
281  */
282 #define SET_LOCKTAG_APPLY_TRANSACTION(locktag,dboid,suboid,xid,objid) \
283  ((locktag).locktag_field1 = (dboid), \
284  (locktag).locktag_field2 = (suboid), \
285  (locktag).locktag_field3 = (xid), \
286  (locktag).locktag_field4 = (objid), \
287  (locktag).locktag_type = LOCKTAG_APPLY_TRANSACTION, \
288  (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
289 
290 /*
291  * Per-locked-object lock information:
292  *
293  * tag -- uniquely identifies the object being locked
294  * grantMask -- bitmask for all lock types currently granted on this object.
295  * waitMask -- bitmask for all lock types currently awaited on this object.
296  * procLocks -- list of PROCLOCK objects for this lock.
297  * waitProcs -- queue of processes waiting for this lock.
298  * requested -- count of each lock type currently requested on the lock
299  * (includes requests already granted!!).
300  * nRequested -- total requested locks of all types.
301  * granted -- count of each lock type currently granted on the lock.
302  * nGranted -- total granted locks of all types.
303  *
304  * Note: these counts count 1 for each backend. Internally to a backend,
305  * there may be multiple grabs on a particular lock, but this is not reflected
306  * into shared memory.
307  */
308 typedef struct LOCK
309 {
310  /* hash key */
311  LOCKTAG tag; /* unique identifier of lockable object */
312 
313  /* data */
314  LOCKMASK grantMask; /* bitmask for lock types already granted */
315  LOCKMASK waitMask; /* bitmask for lock types awaited */
316  dlist_head procLocks; /* list of PROCLOCK objects assoc. with lock */
317  dclist_head waitProcs; /* list of PGPROC objects waiting on lock */
318  int requested[MAX_LOCKMODES]; /* counts of requested locks */
319  int nRequested; /* total of requested[] array */
320  int granted[MAX_LOCKMODES]; /* counts of granted locks */
321  int nGranted; /* total of granted[] array */
323 
324 #define LOCK_LOCKMETHOD(lock) ((LOCKMETHODID) (lock).tag.locktag_lockmethodid)
325 #define LOCK_LOCKTAG(lock) ((LockTagType) (lock).tag.locktag_type)
326 
327 
328 /*
329  * We may have several different backends holding or awaiting locks
330  * on the same lockable object. We need to store some per-holder/waiter
331  * information for each such holder (or would-be holder). This is kept in
332  * a PROCLOCK struct.
333  *
334  * PROCLOCKTAG is the key information needed to look up a PROCLOCK item in the
335  * proclock hashtable. A PROCLOCKTAG value uniquely identifies the combination
336  * of a lockable object and a holder/waiter for that object. (We can use
337  * pointers here because the PROCLOCKTAG need only be unique for the lifespan
338  * of the PROCLOCK, and it will never outlive the lock or the proc.)
339  *
340  * Internally to a backend, it is possible for the same lock to be held
341  * for different purposes: the backend tracks transaction locks separately
342  * from session locks. However, this is not reflected in the shared-memory
343  * state: we only track which backend(s) hold the lock. This is OK since a
344  * backend can never block itself.
345  *
346  * The holdMask field shows the already-granted locks represented by this
347  * proclock. Note that there will be a proclock object, possibly with
348  * zero holdMask, for any lock that the process is currently waiting on.
349  * Otherwise, proclock objects whose holdMasks are zero are recycled
350  * as soon as convenient.
351  *
352  * releaseMask is workspace for LockReleaseAll(): it shows the locks due
353  * to be released during the current call. This must only be examined or
354  * set by the backend owning the PROCLOCK.
355  *
356  * Each PROCLOCK object is linked into lists for both the associated LOCK
357  * object and the owning PGPROC object. Note that the PROCLOCK is entered
358  * into these lists as soon as it is created, even if no lock has yet been
359  * granted. A PGPROC that is waiting for a lock to be granted will also be
360  * linked into the lock's waitProcs queue.
361  */
362 typedef struct PROCLOCKTAG
363 {
364  /* NB: we assume this struct contains no padding! */
365  LOCK *myLock; /* link to per-lockable-object information */
366  PGPROC *myProc; /* link to PGPROC of owning backend */
368 
369 typedef struct PROCLOCK
370 {
371  /* tag */
372  PROCLOCKTAG tag; /* unique identifier of proclock object */
373 
374  /* data */
375  PGPROC *groupLeader; /* proc's lock group leader, or proc itself */
376  LOCKMASK holdMask; /* bitmask for lock types currently held */
377  LOCKMASK releaseMask; /* bitmask for lock types to be released */
378  dlist_node lockLink; /* list link in LOCK's list of proclocks */
379  dlist_node procLink; /* list link in PGPROC's list of proclocks */
381 
382 #define PROCLOCK_LOCKMETHOD(proclock) \
383  LOCK_LOCKMETHOD(*((proclock).tag.myLock))
384 
385 /*
386  * Each backend also maintains a local hash table with information about each
387  * lock it is currently interested in. In particular the local table counts
388  * the number of times that lock has been acquired. This allows multiple
389  * requests for the same lock to be executed without additional accesses to
390  * shared memory. We also track the number of lock acquisitions per
391  * ResourceOwner, so that we can release just those locks belonging to a
392  * particular ResourceOwner.
393  *
394  * When holding a lock taken "normally", the lock and proclock fields always
395  * point to the associated objects in shared memory. However, if we acquired
396  * the lock via the fast-path mechanism, the lock and proclock fields are set
397  * to NULL, since there probably aren't any such objects in shared memory.
398  * (If the lock later gets promoted to normal representation, we may eventually
399  * update our locallock's lock/proclock fields after finding the shared
400  * objects.)
401  *
402  * Caution: a locallock object can be left over from a failed lock acquisition
403  * attempt. In this case its lock/proclock fields are untrustworthy, since
404  * the shared lock object is neither held nor awaited, and hence is available
405  * to be reclaimed. If nLocks > 0 then these pointers must either be valid or
406  * NULL, but when nLocks == 0 they should be considered garbage.
407  */
408 typedef struct LOCALLOCKTAG
409 {
410  LOCKTAG lock; /* identifies the lockable object */
411  LOCKMODE mode; /* lock mode for this table entry */
413 
414 typedef struct LOCALLOCKOWNER
415 {
416  /*
417  * Note: if owner is NULL then the lock is held on behalf of the session;
418  * otherwise it is held on behalf of my current transaction.
419  *
420  * Must use a forward struct reference to avoid circularity.
421  */
423  int64 nLocks; /* # of times held by this owner */
425 
426 typedef struct LOCALLOCK
427 {
428  /* tag */
429  LOCALLOCKTAG tag; /* unique identifier of locallock entry */
430 
431  /* data */
432  uint32 hashcode; /* copy of LOCKTAG's hash value */
433  LOCK *lock; /* associated LOCK object, if any */
434  PROCLOCK *proclock; /* associated PROCLOCK object, if any */
435  int64 nLocks; /* total number of times lock is held */
436  int numLockOwners; /* # of relevant ResourceOwners */
437  int maxLockOwners; /* allocated size of array */
438  LOCALLOCKOWNER *lockOwners; /* dynamically resizable array */
439  bool holdsStrongLockCount; /* bumped FastPathStrongRelationLocks */
440  bool lockCleared; /* we read all sinval msgs for lock */
442 
443 #define LOCALLOCK_LOCKMETHOD(llock) ((llock).tag.lock.locktag_lockmethodid)
444 #define LOCALLOCK_LOCKTAG(llock) ((LockTagType) (llock).tag.lock.locktag_type)
445 
446 
447 /*
448  * These structures hold information passed from lmgr internals to the lock
449  * listing user-level functions (in lockfuncs.c).
450  */
451 
452 typedef struct LockInstanceData
453 {
454  LOCKTAG locktag; /* tag for locked object */
455  LOCKMASK holdMask; /* locks held by this PGPROC */
456  LOCKMODE waitLockMode; /* lock awaited by this PGPROC, if any */
457  BackendId backend; /* backend ID of this PGPROC */
458  LocalTransactionId lxid; /* local transaction ID of this PGPROC */
459  TimestampTz waitStart; /* time at which this PGPROC started waiting
460  * for lock */
461  int pid; /* pid of this PGPROC */
462  int leaderPid; /* pid of group leader; = pid if no group */
463  bool fastpath; /* taken via fastpath? */
465 
466 typedef struct LockData
467 {
468  int nelements; /* The length of the array */
469  LockInstanceData *locks; /* Array of per-PROCLOCK information */
471 
472 typedef struct BlockedProcData
473 {
474  int pid; /* pid of a blocked PGPROC */
475  /* Per-PROCLOCK information about PROCLOCKs of the lock the pid awaits */
476  /* (these fields refer to indexes in BlockedProcsData.locks[]) */
477  int first_lock; /* index of first relevant LockInstanceData */
478  int num_locks; /* number of relevant LockInstanceDatas */
479  /* PIDs of PGPROCs that are ahead of "pid" in the lock's wait queue */
480  /* (these fields refer to indexes in BlockedProcsData.waiter_pids[]) */
481  int first_waiter; /* index of first preceding waiter */
482  int num_waiters; /* number of preceding waiters */
484 
485 typedef struct BlockedProcsData
486 {
487  BlockedProcData *procs; /* Array of per-blocked-proc information */
488  LockInstanceData *locks; /* Array of per-PROCLOCK information */
489  int *waiter_pids; /* Array of PIDs of other blocked PGPROCs */
490  int nprocs; /* # of valid entries in procs[] array */
491  int maxprocs; /* Allocated length of procs[] array */
492  int nlocks; /* # of valid entries in locks[] array */
493  int maxlocks; /* Allocated length of locks[] array */
494  int npids; /* # of valid entries in waiter_pids[] array */
495  int maxpids; /* Allocated length of waiter_pids[] array */
497 
498 
499 /* Result codes for LockAcquire() */
500 typedef enum
501 {
502  LOCKACQUIRE_NOT_AVAIL, /* lock not available, and dontWait=true */
503  LOCKACQUIRE_OK, /* lock successfully acquired */
504  LOCKACQUIRE_ALREADY_HELD, /* incremented count for lock already held */
505  LOCKACQUIRE_ALREADY_CLEAR /* incremented count for lock already clear */
507 
508 /* Deadlock states identified by DeadLockCheck() */
509 typedef enum
510 {
511  DS_NOT_YET_CHECKED, /* no deadlock check has run yet */
512  DS_NO_DEADLOCK, /* no deadlock detected */
513  DS_SOFT_DEADLOCK, /* deadlock avoided by queue rearrangement */
514  DS_HARD_DEADLOCK, /* deadlock, no way out but ERROR */
515  DS_BLOCKED_BY_AUTOVACUUM /* no deadlock; queue blocked by autovacuum
516  * worker */
518 
519 /*
520  * The lockmgr's shared hash tables are partitioned to reduce contention.
521  * To determine which partition a given locktag belongs to, compute the tag's
522  * hash code with LockTagHashCode(), then apply one of these macros.
523  * NB: NUM_LOCK_PARTITIONS must be a power of 2!
524  */
525 #define LockHashPartition(hashcode) \
526  ((hashcode) % NUM_LOCK_PARTITIONS)
527 #define LockHashPartitionLock(hashcode) \
528  (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + \
529  LockHashPartition(hashcode)].lock)
530 #define LockHashPartitionLockByIndex(i) \
531  (&MainLWLockArray[LOCK_MANAGER_LWLOCK_OFFSET + (i)].lock)
532 
533 /*
534  * The deadlock detector needs to be able to access lockGroupLeader and
535  * related fields in the PGPROC, so we arrange for those fields to be protected
536  * by one of the lock hash partition locks. Since the deadlock detector
537  * acquires all such locks anyway, this makes it safe for it to access these
538  * fields without doing anything extra. To avoid contention as much as
539  * possible, we map different PGPROCs to different partition locks. The lock
540  * used for a given lock group is determined by the group leader's pgprocno.
541  */
542 #define LockHashPartitionLockByProc(leader_pgproc) \
543  LockHashPartitionLock((leader_pgproc)->pgprocno)
544 
545 /*
546  * function prototypes
547  */
548 extern void InitLocks(void);
549 extern LockMethod GetLocksMethodTable(const LOCK *lock);
550 extern LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag);
551 extern uint32 LockTagHashCode(const LOCKTAG *locktag);
552 extern bool DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2);
553 extern LockAcquireResult LockAcquire(const LOCKTAG *locktag,
554  LOCKMODE lockmode,
555  bool sessionLock,
556  bool dontWait);
557 extern LockAcquireResult LockAcquireExtended(const LOCKTAG *locktag,
558  LOCKMODE lockmode,
559  bool sessionLock,
560  bool dontWait,
561  bool reportMemoryError,
562  LOCALLOCK **locallockp);
563 extern void AbortStrongLockAcquire(void);
564 extern void MarkLockClear(LOCALLOCK *locallock);
565 extern bool LockRelease(const LOCKTAG *locktag,
566  LOCKMODE lockmode, bool sessionLock);
567 extern void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks);
568 extern void LockReleaseSession(LOCKMETHODID lockmethodid);
569 extern void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks);
570 extern void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks);
571 extern bool LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode);
572 #ifdef USE_ASSERT_CHECKING
573 extern HTAB *GetLockMethodLocalHash(void);
574 #endif
575 extern bool LockHasWaiters(const LOCKTAG *locktag,
576  LOCKMODE lockmode, bool sessionLock);
577 extern VirtualTransactionId *GetLockConflicts(const LOCKTAG *locktag,
578  LOCKMODE lockmode, int *countp);
579 extern void AtPrepare_Locks(void);
580 extern void PostPrepare_Locks(TransactionId xid);
581 extern bool LockCheckConflicts(LockMethod lockMethodTable,
582  LOCKMODE lockmode,
583  LOCK *lock, PROCLOCK *proclock);
584 extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode);
585 extern void GrantAwaitedLock(void);
586 extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode);
587 extern Size LockShmemSize(void);
588 extern LockData *GetLockStatusData(void);
589 extern BlockedProcsData *GetBlockerStatusData(int blocked_pid);
590 
591 extern xl_standby_lock *GetRunningTransactionLocks(int *nlocks);
592 extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode);
593 
594 extern void lock_twophase_recover(TransactionId xid, uint16 info,
595  void *recdata, uint32 len);
596 extern void lock_twophase_postcommit(TransactionId xid, uint16 info,
597  void *recdata, uint32 len);
598 extern void lock_twophase_postabort(TransactionId xid, uint16 info,
599  void *recdata, uint32 len);
601  void *recdata, uint32 len);
602 
603 extern DeadLockState DeadLockCheck(PGPROC *proc);
604 extern PGPROC *GetBlockingAutoVacuumPgproc(void);
605 extern void DeadLockReport(void) pg_attribute_noreturn();
606 extern void RememberSimpleDeadLock(PGPROC *proc1,
607  LOCKMODE lockmode,
608  LOCK *lock,
609  PGPROC *proc2);
610 extern void InitDeadLockChecking(void);
611 
612 extern int LockWaiterCount(const LOCKTAG *locktag);
613 
614 #ifdef LOCK_DEBUG
615 extern void DumpLocks(PGPROC *proc);
616 extern void DumpAllLocks(void);
617 #endif
618 
619 /* Lock a VXID (used to wait for a transaction to finish) */
621 extern void VirtualXactLockTableCleanup(void);
622 extern bool VirtualXactLock(VirtualTransactionId vxid, bool wait);
623 
624 #endif /* LOCK_H_ */
int BackendId
Definition: backendid.h:21
unsigned short uint16
Definition: c.h:489
unsigned int uint32
Definition: c.h:490
#define PGDLLIMPORT
Definition: c.h:1303
#define pg_attribute_noreturn()
Definition: c.h:201
uint32 LocalTransactionId
Definition: c.h:638
unsigned char uint8
Definition: c.h:488
uint32 TransactionId
Definition: c.h:636
size_t Size
Definition: c.h:589
int64 TimestampTz
Definition: timestamp.h:39
LockAcquireResult LockAcquire(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
Definition: lock.c:747
LockAcquireResult LockAcquireExtended(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait, bool reportMemoryError, LOCALLOCK **locallockp)
Definition: lock.c:771
uint16 LOCKMETHODID
Definition: lock.h:122
VirtualTransactionId * GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
Definition: lock.c:2899
PGDLLIMPORT int max_locks_per_xact
Definition: lock.c:55
bool DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
Definition: lock.c:583
struct LOCALLOCK LOCALLOCK
const LockMethodData * LockMethod
Definition: lock.h:116
void VirtualXactLockTableInsert(VirtualTransactionId vxid)
Definition: lock.c:4431
PGPROC * GetBlockingAutoVacuumPgproc(void)
Definition: deadlock.c:287
struct LOCK LOCK
xl_standby_lock * GetRunningTransactionLocks(int *nlocks)
Definition: lock.c:3982
struct PROCLOCK PROCLOCK
LockTagType
Definition: lock.h:136
@ LOCKTAG_OBJECT
Definition: lock.h:145
@ LOCKTAG_RELATION_EXTEND
Definition: lock.h:138
@ LOCKTAG_RELATION
Definition: lock.h:137
@ LOCKTAG_TUPLE
Definition: lock.h:141
@ LOCKTAG_SPECULATIVE_TOKEN
Definition: lock.h:144
@ LOCKTAG_APPLY_TRANSACTION
Definition: lock.h:148
@ LOCKTAG_USERLOCK
Definition: lock.h:146
@ LOCKTAG_DATABASE_FROZEN_IDS
Definition: lock.h:139
@ LOCKTAG_VIRTUALTRANSACTION
Definition: lock.h:143
@ LOCKTAG_TRANSACTION
Definition: lock.h:142
@ LOCKTAG_PAGE
Definition: lock.h:140
@ LOCKTAG_ADVISORY
Definition: lock.h:147
void GrantAwaitedLock(void)
Definition: lock.c:1781
int LockWaiterCount(const LOCKTAG *locktag)
Definition: lock.c:4665
bool LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode)
Definition: lock.c:598
void AtPrepare_Locks(void)
Definition: lock.c:3299
bool LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:1969
void lock_twophase_postcommit(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4381
void RememberSimpleDeadLock(PGPROC *proc1, LOCKMODE lockmode, LOCK *lock, PGPROC *proc2)
Definition: deadlock.c:1145
struct LOCALLOCKOWNER LOCALLOCKOWNER
void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
Definition: lock.c:1550
void VirtualXactLockTableCleanup(void)
Definition: lock.c:4454
BlockedProcsData * GetBlockerStatusData(int blocked_pid)
Definition: lock.c:3808
bool VirtualXactLock(VirtualTransactionId vxid, bool wait)
Definition: lock.c:4554
void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
Definition: lock.c:1913
void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
Definition: lock.c:2174
struct LockMethodData LockMethodData
void InitLocks(void)
Definition: lock.c:405
void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
Definition: lock.c:2564
struct BlockedProcData BlockedProcData
struct LockData LockData
LockData * GetLockStatusData(void)
Definition: lock.c:3616
struct LOCKTAG LOCKTAG
void AbortStrongLockAcquire(void)
Definition: lock.c:1752
DeadLockState
Definition: lock.h:510
@ DS_HARD_DEADLOCK
Definition: lock.h:514
@ DS_BLOCKED_BY_AUTOVACUUM
Definition: lock.h:515
@ DS_NO_DEADLOCK
Definition: lock.h:512
@ DS_NOT_YET_CHECKED
Definition: lock.h:511
@ DS_SOFT_DEADLOCK
Definition: lock.h:513
struct LockInstanceData LockInstanceData
#define MAX_LOCKMODES
Definition: lock.h:82
void lock_twophase_postabort(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4407
bool LockHasWaiters(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
Definition: lock.c:634
struct PROCLOCKTAG PROCLOCKTAG
PGDLLIMPORT const char *const LockTagTypeNames[]
Definition: lockfuncs.c:29
void lock_twophase_standby_recover(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4349
void InitDeadLockChecking(void)
Definition: deadlock.c:143
void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
Definition: lock.c:2469
void lock_twophase_recover(TransactionId xid, uint16 info, void *recdata, uint32 len)
Definition: lock.c:4168
void LockReleaseSession(LOCKMETHODID lockmethodid)
Definition: lock.c:2439
Size LockShmemSize(void)
Definition: lock.c:3579
void MarkLockClear(LOCALLOCK *locallock)
Definition: lock.c:1794
const char * GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
Definition: lock.c:4064
DeadLockState DeadLockCheck(PGPROC *proc)
Definition: deadlock.c:217
void DeadLockReport(void) pg_attribute_noreturn()
Definition: deadlock.c:1073
uint32 LockTagHashCode(const LOCKTAG *locktag)
Definition: lock.c:517
bool LockCheckConflicts(LockMethod lockMethodTable, LOCKMODE lockmode, LOCK *lock, PROCLOCK *proclock)
Definition: lock.c:1419
struct LOCALLOCKTAG LOCALLOCKTAG
LockMethod GetLocksMethodTable(const LOCK *lock)
Definition: lock.c:487
void PostPrepare_Locks(TransactionId xid)
Definition: lock.c:3395
LockAcquireResult
Definition: lock.h:501
@ LOCKACQUIRE_ALREADY_CLEAR
Definition: lock.h:505
@ LOCKACQUIRE_OK
Definition: lock.h:503
@ LOCKACQUIRE_ALREADY_HELD
Definition: lock.h:504
@ LOCKACQUIRE_NOT_AVAIL
Definition: lock.h:502
struct BlockedProcsData BlockedProcsData
LockMethod GetLockTagsMethodTable(const LOCKTAG *locktag)
Definition: lock.c:499
int LOCKMODE
Definition: lockdefs.h:26
int LOCKMASK
Definition: lockdefs.h:25
static PgChecksumMode mode
Definition: pg_checksums.c:65
const void size_t len
int first_lock
Definition: lock.h:477
int first_waiter
Definition: lock.h:481
int num_waiters
Definition: lock.h:482
int num_locks
Definition: lock.h:478
int maxprocs
Definition: lock.h:491
int maxlocks
Definition: lock.h:493
LockInstanceData * locks
Definition: lock.h:488
int * waiter_pids
Definition: lock.h:489
BlockedProcData * procs
Definition: lock.h:487
Definition: dynahash.c:220
int64 nLocks
Definition: lock.h:423
struct ResourceOwnerData * owner
Definition: lock.h:422
LOCKTAG lock
Definition: lock.h:410
LOCKMODE mode
Definition: lock.h:411
LOCALLOCKOWNER * lockOwners
Definition: lock.h:438
uint32 hashcode
Definition: lock.h:432
int maxLockOwners
Definition: lock.h:437
LOCK * lock
Definition: lock.h:433
int64 nLocks
Definition: lock.h:435
int numLockOwners
Definition: lock.h:436
bool holdsStrongLockCount
Definition: lock.h:439
PROCLOCK * proclock
Definition: lock.h:434
LOCALLOCKTAG tag
Definition: lock.h:429
bool lockCleared
Definition: lock.h:440
Definition: lock.h:165
uint8 locktag_type
Definition: lock.h:170
uint32 locktag_field3
Definition: lock.h:168
uint32 locktag_field1
Definition: lock.h:166
uint8 locktag_lockmethodid
Definition: lock.h:171
uint16 locktag_field4
Definition: lock.h:169
uint32 locktag_field2
Definition: lock.h:167
Definition: lock.h:309
int nRequested
Definition: lock.h:319
LOCKTAG tag
Definition: lock.h:311
int requested[MAX_LOCKMODES]
Definition: lock.h:318
dclist_head waitProcs
Definition: lock.h:317
int granted[MAX_LOCKMODES]
Definition: lock.h:320
LOCKMASK grantMask
Definition: lock.h:314
LOCKMASK waitMask
Definition: lock.h:315
int nGranted
Definition: lock.h:321
dlist_head procLocks
Definition: lock.h:316
Definition: lock.h:467
LockInstanceData * locks
Definition: lock.h:469
int nelements
Definition: lock.h:468
LOCKMASK holdMask
Definition: lock.h:455
LOCKMODE waitLockMode
Definition: lock.h:456
bool fastpath
Definition: lock.h:463
LOCKTAG locktag
Definition: lock.h:454
TimestampTz waitStart
Definition: lock.h:459
int leaderPid
Definition: lock.h:462
BackendId backend
Definition: lock.h:457
LocalTransactionId lxid
Definition: lock.h:458
const bool * trace_flag
Definition: lock.h:113
const LOCKMASK * conflictTab
Definition: lock.h:111
const char *const * lockModeNames
Definition: lock.h:112
int numLockModes
Definition: lock.h:110
Definition: proc.h:162
LOCK * myLock
Definition: lock.h:365
PGPROC * myProc
Definition: lock.h:366
Definition: lock.h:370
LOCKMASK holdMask
Definition: lock.h:376
dlist_node lockLink
Definition: lock.h:378
PGPROC * groupLeader
Definition: lock.h:375
LOCKMASK releaseMask
Definition: lock.h:377
PROCLOCKTAG tag
Definition: lock.h:372
dlist_node procLink
Definition: lock.h:379
LocalTransactionId localTransactionId
Definition: lock.h:62
BackendId backendId
Definition: lock.h:61