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fsm_internals.h
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1/*-------------------------------------------------------------------------
2 *
3 * fsm_internals.h
4 * internal functions for free space map
5 *
6 *
7 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 * src/include/storage/fsm_internals.h
11 *
12 *-------------------------------------------------------------------------
13 */
14#ifndef FSM_INTERNALS_H
15#define FSM_INTERNALS_H
16
17#include "storage/buf.h"
18#include "storage/bufpage.h"
19
20/*
21 * Structure of a FSM page. See src/backend/storage/freespace/README for
22 * details.
23 */
24typedef struct
25{
26 /*
27 * fsm_search_avail() tries to spread the load of multiple backends by
28 * returning different pages to different backends in a round-robin
29 * fashion. fp_next_slot points to the next slot to be returned (assuming
30 * there's enough space on it for the request). It's defined as an int,
31 * because it's updated without an exclusive lock. uint16 would be more
32 * appropriate, but int is more likely to be atomically
33 * fetchable/storable.
34 */
36
37 /*
38 * fp_nodes contains the binary tree, stored in array. The first
39 * NonLeafNodesPerPage elements are upper nodes, and the following
40 * LeafNodesPerPage elements are leaf nodes. Unused nodes are zero.
41 */
44
46
47/*
48 * Number of non-leaf and leaf nodes, and nodes in total, on an FSM page.
49 * These definitions are internal to fsmpage.c.
50 */
51#define NodesPerPage (BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - \
52 offsetof(FSMPageData, fp_nodes))
53
54#define NonLeafNodesPerPage (BLCKSZ / 2 - 1)
55#define LeafNodesPerPage (NodesPerPage - NonLeafNodesPerPage)
56
57/*
58 * Number of FSM "slots" on a FSM page. This is what should be used
59 * outside fsmpage.c.
60 */
61#define SlotsPerFSMPage LeafNodesPerPage
62
63/* Prototypes for functions in fsmpage.c */
64extern int fsm_search_avail(Buffer buf, uint8 minvalue, bool advancenext,
65 bool exclusive_lock_held);
66extern uint8 fsm_get_avail(Page page, int slot);
67extern uint8 fsm_get_max_avail(Page page);
68extern bool fsm_set_avail(Page page, int slot, uint8 value);
69extern bool fsm_truncate_avail(Page page, int nslots);
70extern bool fsm_rebuild_page(Page page);
71
72#endif /* FSM_INTERNALS_H */
int Buffer
Definition: buf.h:23
PageData * Page
Definition: bufpage.h:82
uint8_t uint8
Definition: c.h:486
#define FLEXIBLE_ARRAY_MEMBER
Definition: c.h:420
FSMPageData * FSMPage
Definition: fsm_internals.h:45
uint8 fsm_get_avail(Page page, int slot)
Definition: fsmpage.c:122
bool fsm_rebuild_page(Page page)
Definition: fsmpage.c:342
uint8 fsm_get_max_avail(Page page)
Definition: fsmpage.c:138
bool fsm_set_avail(Page page, int slot, uint8 value)
Definition: fsmpage.c:63
bool fsm_truncate_avail(Page page, int nslots)
Definition: fsmpage.c:313
int fsm_search_avail(Buffer buf, uint8 minvalue, bool advancenext, bool exclusive_lock_held)
Definition: fsmpage.c:158
static struct @162 value
static char * buf
Definition: pg_test_fsync.c:72