Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * buf_internals.h
4 : * Internal definitions for buffer manager and the buffer replacement
5 : * strategy.
6 : *
7 : *
8 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
9 : * Portions Copyright (c) 1994, Regents of the University of California
10 : *
11 : * src/include/storage/buf_internals.h
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #ifndef BUFMGR_INTERNALS_H
16 : #define BUFMGR_INTERNALS_H
17 :
18 : #include "pgstat.h"
19 : #include "port/atomics.h"
20 : #include "storage/aio_types.h"
21 : #include "storage/buf.h"
22 : #include "storage/bufmgr.h"
23 : #include "storage/condition_variable.h"
24 : #include "storage/lwlock.h"
25 : #include "storage/procnumber.h"
26 : #include "storage/proclist_types.h"
27 : #include "storage/shmem.h"
28 : #include "storage/smgr.h"
29 : #include "storage/spin.h"
30 : #include "utils/relcache.h"
31 : #include "utils/resowner.h"
32 :
33 : /*
34 : * Buffer state is a single 64-bit variable where following data is combined.
35 : *
36 : * State of the buffer itself (in order):
37 : * - 18 bits refcount
38 : * - 4 bits usage count
39 : * - 12 bits of flags
40 : * - 18 bits share-lock count
41 : * - 1 bit share-exclusive locked
42 : * - 1 bit exclusive locked
43 : *
44 : * Combining these values allows to perform some operations without locking
45 : * the buffer header, by modifying them together with a CAS loop.
46 : *
47 : * The definition of buffer state components is below.
48 : */
49 : #define BUF_REFCOUNT_BITS 18
50 : #define BUF_USAGECOUNT_BITS 4
51 : #define BUF_FLAG_BITS 12
52 : #define BUF_LOCK_BITS (18+2)
53 :
54 : StaticAssertDecl(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + BUF_FLAG_BITS + BUF_LOCK_BITS <= 64,
55 : "parts of buffer state space need to be <= 64");
56 :
57 : /* refcount related definitions */
58 : #define BUF_REFCOUNT_ONE 1
59 : #define BUF_REFCOUNT_MASK \
60 : ((UINT64CONST(1) << BUF_REFCOUNT_BITS) - 1)
61 :
62 : /* usage count related definitions */
63 : #define BUF_USAGECOUNT_SHIFT \
64 : BUF_REFCOUNT_BITS
65 : #define BUF_USAGECOUNT_MASK \
66 : (((UINT64CONST(1) << BUF_USAGECOUNT_BITS) - 1) << (BUF_USAGECOUNT_SHIFT))
67 : #define BUF_USAGECOUNT_ONE \
68 : (UINT64CONST(1) << BUF_REFCOUNT_BITS)
69 :
70 : /* flags related definitions */
71 : #define BUF_FLAG_SHIFT \
72 : (BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS)
73 : #define BUF_FLAG_MASK \
74 : (((UINT64CONST(1) << BUF_FLAG_BITS) - 1) << BUF_FLAG_SHIFT)
75 :
76 : /* lock state related definitions */
77 : #define BM_LOCK_SHIFT \
78 : (BUF_FLAG_SHIFT + BUF_FLAG_BITS)
79 : #define BM_LOCK_VAL_SHARED \
80 : (UINT64CONST(1) << (BM_LOCK_SHIFT))
81 : #define BM_LOCK_VAL_SHARE_EXCLUSIVE \
82 : (UINT64CONST(1) << (BM_LOCK_SHIFT + MAX_BACKENDS_BITS))
83 : #define BM_LOCK_VAL_EXCLUSIVE \
84 : (UINT64CONST(1) << (BM_LOCK_SHIFT + MAX_BACKENDS_BITS + 1))
85 : #define BM_LOCK_MASK \
86 : ((((uint64) MAX_BACKENDS) << BM_LOCK_SHIFT) | BM_LOCK_VAL_SHARE_EXCLUSIVE | BM_LOCK_VAL_EXCLUSIVE)
87 :
88 :
89 : /* Get refcount and usagecount from buffer state */
90 : #define BUF_STATE_GET_REFCOUNT(state) \
91 : ((uint32)((state) & BUF_REFCOUNT_MASK))
92 : #define BUF_STATE_GET_USAGECOUNT(state) \
93 : ((uint32)(((state) & BUF_USAGECOUNT_MASK) >> BUF_USAGECOUNT_SHIFT))
94 :
95 : /*
96 : * Flags for buffer descriptors
97 : *
98 : * Note: BM_TAG_VALID essentially means that there is a buffer hashtable
99 : * entry associated with the buffer's tag.
100 : */
101 :
102 : #define BUF_DEFINE_FLAG(flagno) \
103 : (UINT64CONST(1) << (BUF_FLAG_SHIFT + (flagno)))
104 :
105 : /* buffer header is locked */
106 : #define BM_LOCKED BUF_DEFINE_FLAG( 0)
107 : /* data needs writing */
108 : #define BM_DIRTY BUF_DEFINE_FLAG( 1)
109 : /* data is valid */
110 : #define BM_VALID BUF_DEFINE_FLAG( 2)
111 : /* tag is assigned */
112 : #define BM_TAG_VALID BUF_DEFINE_FLAG( 3)
113 : /* read or write in progress */
114 : #define BM_IO_IN_PROGRESS BUF_DEFINE_FLAG( 4)
115 : /* previous I/O failed */
116 : #define BM_IO_ERROR BUF_DEFINE_FLAG( 5)
117 : /* dirtied since write started */
118 : #define BM_JUST_DIRTIED BUF_DEFINE_FLAG( 6)
119 : /* have waiter for sole pin */
120 : #define BM_PIN_COUNT_WAITER BUF_DEFINE_FLAG( 7)
121 : /* must write for checkpoint */
122 : #define BM_CHECKPOINT_NEEDED BUF_DEFINE_FLAG( 8)
123 : /* permanent buffer (not unlogged, or init fork) */
124 : #define BM_PERMANENT BUF_DEFINE_FLAG( 9)
125 : /* content lock has waiters */
126 : #define BM_LOCK_HAS_WAITERS BUF_DEFINE_FLAG(10)
127 : /* waiter for content lock has been signalled but not yet run */
128 : #define BM_LOCK_WAKE_IN_PROGRESS BUF_DEFINE_FLAG(11)
129 :
130 :
131 : StaticAssertDecl(MAX_BACKENDS_BITS <= BUF_REFCOUNT_BITS,
132 : "MAX_BACKENDS_BITS needs to be <= BUF_REFCOUNT_BITS");
133 : StaticAssertDecl(MAX_BACKENDS_BITS <= (BUF_LOCK_BITS - 2),
134 : "MAX_BACKENDS_BITS needs to be <= BUF_LOCK_BITS - 2");
135 :
136 :
137 : /*
138 : * The maximum allowed value of usage_count represents a tradeoff between
139 : * accuracy and speed of the clock-sweep buffer management algorithm. A
140 : * large value (comparable to NBuffers) would approximate LRU semantics.
141 : * But it can take as many as BM_MAX_USAGE_COUNT+1 complete cycles of the
142 : * clock-sweep hand to find a free buffer, so in practice we don't want the
143 : * value to be very large.
144 : */
145 : #define BM_MAX_USAGE_COUNT 5
146 :
147 : StaticAssertDecl(BM_MAX_USAGE_COUNT < (UINT64CONST(1) << BUF_USAGECOUNT_BITS),
148 : "BM_MAX_USAGE_COUNT doesn't fit in BUF_USAGECOUNT_BITS bits");
149 :
150 : /*
151 : * Buffer tag identifies which disk block the buffer contains.
152 : *
153 : * Note: the BufferTag data must be sufficient to determine where to write the
154 : * block, without reference to pg_class or pg_tablespace entries. It's
155 : * possible that the backend flushing the buffer doesn't even believe the
156 : * relation is visible yet (its xact may have started before the xact that
157 : * created the rel). The storage manager must be able to cope anyway.
158 : *
159 : * Note: if there's any pad bytes in the struct, InitBufferTag will have
160 : * to be fixed to zero them, since this struct is used as a hash key.
161 : */
162 : typedef struct buftag
163 : {
164 : Oid spcOid; /* tablespace oid */
165 : Oid dbOid; /* database oid */
166 : RelFileNumber relNumber; /* relation file number */
167 : ForkNumber forkNum; /* fork number */
168 : BlockNumber blockNum; /* blknum relative to begin of reln */
169 : } BufferTag;
170 :
171 : static inline RelFileNumber
172 162613226 : BufTagGetRelNumber(const BufferTag *tag)
173 : {
174 162613226 : return tag->relNumber;
175 : }
176 :
177 : static inline ForkNumber
178 22958738 : BufTagGetForkNum(const BufferTag *tag)
179 : {
180 22958738 : return tag->forkNum;
181 : }
182 :
183 : static inline void
184 76388259 : BufTagSetRelForkDetails(BufferTag *tag, RelFileNumber relnumber,
185 : ForkNumber forknum)
186 : {
187 76388259 : tag->relNumber = relnumber;
188 76388259 : tag->forkNum = forknum;
189 76388259 : }
190 :
191 : static inline RelFileLocator
192 18463432 : BufTagGetRelFileLocator(const BufferTag *tag)
193 : {
194 : RelFileLocator rlocator;
195 :
196 18463432 : rlocator.spcOid = tag->spcOid;
197 18463432 : rlocator.dbOid = tag->dbOid;
198 18463432 : rlocator.relNumber = BufTagGetRelNumber(tag);
199 :
200 18463432 : return rlocator;
201 : }
202 :
203 : static inline void
204 12175347 : ClearBufferTag(BufferTag *tag)
205 : {
206 12175347 : tag->spcOid = InvalidOid;
207 12175347 : tag->dbOid = InvalidOid;
208 12175347 : BufTagSetRelForkDetails(tag, InvalidRelFileNumber, InvalidForkNumber);
209 12175347 : tag->blockNum = InvalidBlockNumber;
210 12175347 : }
211 :
212 : static inline void
213 64212912 : InitBufferTag(BufferTag *tag, const RelFileLocator *rlocator,
214 : ForkNumber forkNum, BlockNumber blockNum)
215 : {
216 64212912 : tag->spcOid = rlocator->spcOid;
217 64212912 : tag->dbOid = rlocator->dbOid;
218 64212912 : BufTagSetRelForkDetails(tag, rlocator->relNumber, forkNum);
219 64212912 : tag->blockNum = blockNum;
220 64212912 : }
221 :
222 : static inline bool
223 115462 : BufferTagsEqual(const BufferTag *tag1, const BufferTag *tag2)
224 : {
225 230922 : return (tag1->spcOid == tag2->spcOid) &&
226 115460 : (tag1->dbOid == tag2->dbOid) &&
227 115460 : (tag1->relNumber == tag2->relNumber) &&
228 346340 : (tag1->blockNum == tag2->blockNum) &&
229 115418 : (tag1->forkNum == tag2->forkNum);
230 : }
231 :
232 : static inline bool
233 430752474 : BufTagMatchesRelFileLocator(const BufferTag *tag,
234 : const RelFileLocator *rlocator)
235 : {
236 608567192 : return (tag->spcOid == rlocator->spcOid) &&
237 574566064 : (tag->dbOid == rlocator->dbOid) &&
238 143813590 : (BufTagGetRelNumber(tag) == rlocator->relNumber);
239 : }
240 :
241 :
242 : /*
243 : * The shared buffer mapping table is partitioned to reduce contention.
244 : * To determine which partition lock a given tag requires, compute the tag's
245 : * hash code with BufTableHashCode(), then apply BufMappingPartitionLock().
246 : * NB: NUM_BUFFER_PARTITIONS must be a power of 2!
247 : */
248 : static inline uint32
249 64277203 : BufTableHashPartition(uint32 hashcode)
250 : {
251 64277203 : return hashcode % NUM_BUFFER_PARTITIONS;
252 : }
253 :
254 : static inline LWLock *
255 64277203 : BufMappingPartitionLock(uint32 hashcode)
256 : {
257 64277203 : return &MainLWLockArray[BUFFER_MAPPING_LWLOCK_OFFSET +
258 64277203 : BufTableHashPartition(hashcode)].lock;
259 : }
260 :
261 : static inline LWLock *
262 : BufMappingPartitionLockByIndex(uint32 index)
263 : {
264 : return &MainLWLockArray[BUFFER_MAPPING_LWLOCK_OFFSET + index].lock;
265 : }
266 :
267 : /*
268 : * BufferDesc -- shared descriptor/state data for a single shared buffer.
269 : *
270 : * The state of the buffer is controlled by the, drumroll, state variable. It
271 : * only may be modified using atomic operations. The state variable combines
272 : * various flags, the buffer's refcount and usage count. See comment above
273 : * BUF_REFCOUNT_BITS for details about the division. This layout allow us to
274 : * do some operations in a single atomic operation, without actually acquiring
275 : * and releasing the spinlock; for instance, increasing or decreasing the
276 : * refcount.
277 : *
278 : * One of the aforementioned flags is BM_LOCKED, used to implement the buffer
279 : * header lock. See the following paragraphs, as well as the documentation for
280 : * individual fields, for more details.
281 : *
282 : * The identity of the buffer (BufferDesc.tag) can only be changed by the
283 : * backend holding the buffer header lock.
284 : *
285 : * If the lock is held by another backend, neither additional buffer pins may
286 : * be established (we would like to relax this eventually), nor can flags be
287 : * set/cleared. These operations either need to acquire the buffer header
288 : * spinlock, or need to use a CAS loop, waiting for the lock to be released if
289 : * it is held. However, existing buffer pins may be released while the buffer
290 : * header spinlock is held, using an atomic subtraction.
291 : *
292 : * If we have the buffer pinned, its tag can't change underneath us, so we can
293 : * examine the tag without locking the buffer header. Also, in places we do
294 : * one-time reads of the flags without bothering to lock the buffer header;
295 : * this is generally for situations where we don't expect the flag bit being
296 : * tested to be changing.
297 : *
298 : * We can't physically remove items from a disk page if another backend has
299 : * the buffer pinned. Hence, a backend may need to wait for all other pins
300 : * to go away. This is signaled by storing its own pgprocno into
301 : * wait_backend_pgprocno and setting flag bit BM_PIN_COUNT_WAITER. At present,
302 : * there can be only one such waiter per buffer.
303 : *
304 : * The content of buffers is protected via the buffer content lock,
305 : * implemented as part of the buffer state. Note that the buffer header lock
306 : * is *not* used to control access to the data in the buffer! We used to use
307 : * an LWLock to implement the content lock, but having a dedicated
308 : * implementation of content locks allows us to implement some otherwise hard
309 : * things (e.g. race-freely checking if AIO is in progress before locking a
310 : * buffer exclusively) and enables otherwise impossible optimizations
311 : * (e.g. unlocking and unpinning a buffer in one atomic operation).
312 : *
313 : * We use this same struct for local buffer headers, but the locks are not
314 : * used and not all of the flag bits are useful either. To avoid unnecessary
315 : * overhead, manipulations of the state field should be done without actual
316 : * atomic operations (i.e. only pg_atomic_read_u64() and
317 : * pg_atomic_unlocked_write_u64()).
318 : *
319 : * Be careful to avoid increasing the size of the struct when adding or
320 : * reordering members. Keeping it below 64 bytes (the most common CPU
321 : * cache line size) is fairly important for performance.
322 : *
323 : * Per-buffer I/O condition variables are currently kept outside this struct in
324 : * a separate array. They could be moved in here and still fit within that
325 : * limit on common systems, but for now that is not done.
326 : */
327 : typedef struct BufferDesc
328 : {
329 : /*
330 : * ID of page contained in buffer. The buffer header spinlock needs to be
331 : * held to modify this field.
332 : */
333 : BufferTag tag;
334 :
335 : /*
336 : * Buffer's index number (from 0). The field never changes after
337 : * initialization, so does not need locking.
338 : */
339 : int buf_id;
340 :
341 : /*
342 : * State of the buffer, containing flags, refcount and usagecount. See
343 : * BUF_* and BM_* defines at the top of this file.
344 : */
345 : pg_atomic_uint64 state;
346 :
347 : /*
348 : * Backend of pin-count waiter. The buffer header spinlock needs to be
349 : * held to modify this field.
350 : */
351 : int wait_backend_pgprocno;
352 :
353 : PgAioWaitRef io_wref; /* set iff AIO is in progress */
354 :
355 : /*
356 : * List of PGPROCs waiting for the buffer content lock. Protected by the
357 : * buffer header spinlock.
358 : */
359 : proclist_head lock_waiters;
360 : } BufferDesc;
361 :
362 : /*
363 : * Concurrent access to buffer headers has proven to be more efficient if
364 : * they're cache line aligned. So we force the start of the BufferDescriptors
365 : * array to be on a cache line boundary and force the elements to be cache
366 : * line sized.
367 : *
368 : * XXX: As this is primarily matters in highly concurrent workloads which
369 : * probably all are 64bit these days, and the space wastage would be a bit
370 : * more noticeable on 32bit systems, we don't force the stride to be cache
371 : * line sized on those. If somebody does actual performance testing, we can
372 : * reevaluate.
373 : *
374 : * Note that local buffer descriptors aren't forced to be aligned - as there's
375 : * no concurrent access to those it's unlikely to be beneficial.
376 : *
377 : * We use a 64-byte cache line size here, because that's the most common
378 : * size. Making it bigger would be a waste of memory. Even if running on a
379 : * platform with either 32 or 128 byte line sizes, it's good to align to
380 : * boundaries and avoid false sharing.
381 : */
382 : #define BUFFERDESC_PAD_TO_SIZE (SIZEOF_VOID_P == 8 ? 64 : 1)
383 :
384 : typedef union BufferDescPadded
385 : {
386 : BufferDesc bufferdesc;
387 : char pad[BUFFERDESC_PAD_TO_SIZE];
388 : } BufferDescPadded;
389 :
390 : /*
391 : * The PendingWriteback & WritebackContext structure are used to keep
392 : * information about pending flush requests to be issued to the OS.
393 : */
394 : typedef struct PendingWriteback
395 : {
396 : /* could store different types of pending flushes here */
397 : BufferTag tag;
398 : } PendingWriteback;
399 :
400 : /* struct forward declared in bufmgr.h */
401 : typedef struct WritebackContext
402 : {
403 : /* pointer to the max number of writeback requests to coalesce */
404 : int *max_pending;
405 :
406 : /* current number of pending writeback requests */
407 : int nr_pending;
408 :
409 : /* pending requests */
410 : PendingWriteback pending_writebacks[WRITEBACK_MAX_PENDING_FLUSHES];
411 : } WritebackContext;
412 :
413 : /* in buf_init.c */
414 : extern PGDLLIMPORT BufferDescPadded *BufferDescriptors;
415 : extern PGDLLIMPORT ConditionVariableMinimallyPadded *BufferIOCVArray;
416 : extern PGDLLIMPORT WritebackContext BackendWritebackContext;
417 :
418 : /* in localbuf.c */
419 : extern PGDLLIMPORT BufferDesc *LocalBufferDescriptors;
420 :
421 :
422 : static inline BufferDesc *
423 605546129 : GetBufferDescriptor(uint32 id)
424 : {
425 605546129 : return &(BufferDescriptors[id]).bufferdesc;
426 : }
427 :
428 : static inline BufferDesc *
429 10101769 : GetLocalBufferDescriptor(uint32 id)
430 : {
431 10101769 : return &LocalBufferDescriptors[id];
432 : }
433 :
434 : static inline Buffer
435 286402024 : BufferDescriptorGetBuffer(const BufferDesc *bdesc)
436 : {
437 286402024 : return (Buffer) (bdesc->buf_id + 1);
438 : }
439 :
440 : static inline ConditionVariable *
441 13235007 : BufferDescriptorGetIOCV(const BufferDesc *bdesc)
442 : {
443 13235007 : return &(BufferIOCVArray[bdesc->buf_id]).cv;
444 : }
445 :
446 : /*
447 : * Functions for acquiring/releasing a shared buffer header's spinlock. Do
448 : * not apply these to local buffers!
449 : */
450 : extern uint64 LockBufHdr(BufferDesc *desc);
451 :
452 : /*
453 : * Unlock the buffer header.
454 : *
455 : * This can only be used if the caller did not modify BufferDesc.state. To
456 : * set/unset flag bits or change the refcount use UnlockBufHdrExt().
457 : */
458 : static inline void
459 9972505 : UnlockBufHdr(BufferDesc *desc)
460 : {
461 : Assert(pg_atomic_read_u64(&desc->state) & BM_LOCKED);
462 :
463 9972505 : pg_atomic_fetch_sub_u64(&desc->state, BM_LOCKED);
464 9972505 : }
465 :
466 : /*
467 : * Unlock the buffer header, while atomically adding the flags in set_bits,
468 : * unsetting the ones in unset_bits and changing the refcount by
469 : * refcount_change.
470 : *
471 : * Note that this approach would not work for usagecount, since we need to cap
472 : * the usagecount at BM_MAX_USAGE_COUNT.
473 : */
474 : static inline uint64
475 23362355 : UnlockBufHdrExt(BufferDesc *desc, uint64 old_buf_state,
476 : uint64 set_bits, uint64 unset_bits,
477 : int refcount_change)
478 : {
479 : for (;;)
480 13 : {
481 23362368 : uint64 buf_state = old_buf_state;
482 :
483 : Assert(buf_state & BM_LOCKED);
484 :
485 23362368 : buf_state |= set_bits;
486 23362368 : buf_state &= ~unset_bits;
487 23362368 : buf_state &= ~BM_LOCKED;
488 :
489 23362368 : if (refcount_change != 0)
490 3147931 : buf_state += BUF_REFCOUNT_ONE * refcount_change;
491 :
492 23362368 : if (pg_atomic_compare_exchange_u64(&desc->state, &old_buf_state,
493 : buf_state))
494 : {
495 23362355 : return old_buf_state;
496 : }
497 : }
498 : }
499 :
500 : extern uint64 WaitBufHdrUnlocked(BufferDesc *buf);
501 :
502 : /* in bufmgr.c */
503 :
504 : /*
505 : * Structure to sort buffers per file on checkpoints.
506 : *
507 : * This structure is allocated per buffer in shared memory, so it should be
508 : * kept as small as possible.
509 : */
510 : typedef struct CkptSortItem
511 : {
512 : Oid tsId;
513 : RelFileNumber relNumber;
514 : ForkNumber forkNum;
515 : BlockNumber blockNum;
516 : int buf_id;
517 : } CkptSortItem;
518 :
519 : extern PGDLLIMPORT CkptSortItem *CkptBufferIds;
520 :
521 : /* ResourceOwner callbacks to hold buffer I/Os and pins */
522 : extern PGDLLIMPORT const ResourceOwnerDesc buffer_io_resowner_desc;
523 : extern PGDLLIMPORT const ResourceOwnerDesc buffer_resowner_desc;
524 :
525 : /* Convenience wrappers over ResourceOwnerRemember/Forget */
526 : static inline void
527 76676934 : ResourceOwnerRememberBuffer(ResourceOwner owner, Buffer buffer)
528 : {
529 76676934 : ResourceOwnerRemember(owner, Int32GetDatum(buffer), &buffer_resowner_desc);
530 76676934 : }
531 : static inline void
532 76669224 : ResourceOwnerForgetBuffer(ResourceOwner owner, Buffer buffer)
533 : {
534 76669224 : ResourceOwnerForget(owner, Int32GetDatum(buffer), &buffer_resowner_desc);
535 76669224 : }
536 : static inline void
537 2581615 : ResourceOwnerRememberBufferIO(ResourceOwner owner, Buffer buffer)
538 : {
539 2581615 : ResourceOwnerRemember(owner, Int32GetDatum(buffer), &buffer_io_resowner_desc);
540 2581615 : }
541 : static inline void
542 2581600 : ResourceOwnerForgetBufferIO(ResourceOwner owner, Buffer buffer)
543 : {
544 2581600 : ResourceOwnerForget(owner, Int32GetDatum(buffer), &buffer_io_resowner_desc);
545 2581600 : }
546 :
547 : /*
548 : * Internal buffer management routines
549 : */
550 : /* bufmgr.c */
551 : extern void WritebackContextInit(WritebackContext *context, int *max_pending);
552 : extern void IssuePendingWritebacks(WritebackContext *wb_context, IOContext io_context);
553 : extern void ScheduleBufferTagForWriteback(WritebackContext *wb_context,
554 : IOContext io_context, BufferTag *tag);
555 :
556 : extern void TrackNewBufferPin(Buffer buf);
557 :
558 : /* solely to make it easier to write tests */
559 : extern bool StartBufferIO(BufferDesc *buf, bool forInput, bool nowait);
560 : extern void TerminateBufferIO(BufferDesc *buf, bool clear_dirty, uint64 set_flag_bits,
561 : bool forget_owner, bool release_aio);
562 :
563 :
564 : /* freelist.c */
565 : extern IOContext IOContextForStrategy(BufferAccessStrategy strategy);
566 : extern BufferDesc *StrategyGetBuffer(BufferAccessStrategy strategy,
567 : uint64 *buf_state, bool *from_ring);
568 : extern bool StrategyRejectBuffer(BufferAccessStrategy strategy,
569 : BufferDesc *buf, bool from_ring);
570 :
571 : extern int StrategySyncStart(uint32 *complete_passes, uint32 *num_buf_alloc);
572 : extern void StrategyNotifyBgWriter(int bgwprocno);
573 :
574 : extern Size StrategyShmemSize(void);
575 : extern void StrategyInitialize(bool init);
576 :
577 : /* buf_table.c */
578 : extern Size BufTableShmemSize(int size);
579 : extern void InitBufTable(int size);
580 : extern uint32 BufTableHashCode(BufferTag *tagPtr);
581 : extern int BufTableLookup(BufferTag *tagPtr, uint32 hashcode);
582 : extern int BufTableInsert(BufferTag *tagPtr, uint32 hashcode, int buf_id);
583 : extern void BufTableDelete(BufferTag *tagPtr, uint32 hashcode);
584 :
585 : /* localbuf.c */
586 : extern bool PinLocalBuffer(BufferDesc *buf_hdr, bool adjust_usagecount);
587 : extern void UnpinLocalBuffer(Buffer buffer);
588 : extern void UnpinLocalBufferNoOwner(Buffer buffer);
589 : extern PrefetchBufferResult PrefetchLocalBuffer(SMgrRelation smgr,
590 : ForkNumber forkNum,
591 : BlockNumber blockNum);
592 : extern BufferDesc *LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum,
593 : BlockNumber blockNum, bool *foundPtr);
594 : extern BlockNumber ExtendBufferedRelLocal(BufferManagerRelation bmr,
595 : ForkNumber fork,
596 : uint32 flags,
597 : uint32 extend_by,
598 : BlockNumber extend_upto,
599 : Buffer *buffers,
600 : uint32 *extended_by);
601 : extern void MarkLocalBufferDirty(Buffer buffer);
602 : extern void TerminateLocalBufferIO(BufferDesc *bufHdr, bool clear_dirty,
603 : uint64 set_flag_bits, bool release_aio);
604 : extern bool StartLocalBufferIO(BufferDesc *bufHdr, bool forInput, bool nowait);
605 : extern void FlushLocalBuffer(BufferDesc *bufHdr, SMgrRelation reln);
606 : extern void InvalidateLocalBuffer(BufferDesc *bufHdr, bool check_unreferenced);
607 : extern void DropRelationLocalBuffers(RelFileLocator rlocator,
608 : ForkNumber *forkNum, int nforks,
609 : BlockNumber *firstDelBlock);
610 : extern void DropRelationAllLocalBuffers(RelFileLocator rlocator);
611 : extern void AtEOXact_LocalBuffers(bool isCommit);
612 :
613 : #endif /* BUFMGR_INTERNALS_H */
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