73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* fsm_internals.h
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* internal functions for free space map
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*
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/fsm_internals.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FSM_INTERNALS_H
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#define FSM_INTERNALS_H
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#include "storage/buf.h"
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#include "storage/bufpage.h"
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/*
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* Structure of a FSM page. See src/backend/storage/freespace/README for
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* details.
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*/
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typedef struct
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{
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/*
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* fsm_search_avail() tries to spread the load of multiple backends by
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* returning different pages to different backends in a round-robin
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* fashion. fp_next_slot points to the next slot to be returned (assuming
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* there's enough space on it for the request). It's defined as an int,
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* because it's updated without an exclusive lock. uint16 would be more
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* appropriate, but int is more likely to be atomically
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* fetchable/storable.
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*/
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int fp_next_slot;
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/*
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* fp_nodes contains the binary tree, stored in array. The first
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* NonLeafNodesPerPage elements are upper nodes, and the following
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* LeafNodesPerPage elements are leaf nodes. Unused nodes are zero.
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*/
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uint8 fp_nodes[FLEXIBLE_ARRAY_MEMBER];
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} FSMPageData;
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typedef FSMPageData *FSMPage;
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/*
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* Number of non-leaf and leaf nodes, and nodes in total, on an FSM page.
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* These definitions are internal to fsmpage.c.
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*/
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#define NodesPerPage (BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - \
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offsetof(FSMPageData, fp_nodes))
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#define NonLeafNodesPerPage (BLCKSZ / 2 - 1)
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#define LeafNodesPerPage (NodesPerPage - NonLeafNodesPerPage)
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/*
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* Number of FSM "slots" on a FSM page. This is what should be used
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* outside fsmpage.c.
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*/
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#define SlotsPerFSMPage LeafNodesPerPage
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/* Prototypes for functions in fsmpage.c */
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extern int fsm_search_avail(Buffer buf, uint8 minvalue, bool advancenext,
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bool exclusive_lock_held);
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extern uint8 fsm_get_avail(Page page, int slot);
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extern uint8 fsm_get_max_avail(Page page);
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extern bool fsm_set_avail(Page page, int slot, uint8 value);
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extern bool fsm_truncate_avail(Page page, int nslots);
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extern bool fsm_rebuild_page(Page page);
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#endif /* FSM_INTERNALS_H */
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