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/*------------------------------------------------------------------------- * * fsm_internal.h * internal functions for free space map * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/storage/fsm_internals.h * *------------------------------------------------------------------------- */ #ifndef FSM_INTERNALS_H #define FSM_INTERNALS_H #include "storage/buf.h" #include "storage/bufpage.h" /* * Structure of a FSM page. See src/backend/storage/freespace/README for * details. */ typedef struct { /* * fsm_search_avail() tries to spread the load of multiple backends by * returning different pages to different backends in a round-robin * fashion. fp_next_slot points to the next slot to be returned (assuming * there's enough space on it for the request). It's defined as an int, * because it's updated without an exclusive lock. uint16 would be more * appropriate, but int is more likely to be atomically * fetchable/storable. */ int fp_next_slot; /* * fp_nodes contains the binary tree, stored in array. The first * NonLeafNodesPerPage elements are upper nodes, and the following * LeafNodesPerPage elements are leaf nodes. Unused nodes are zero. */ uint8 fp_nodes[1]; } FSMPageData; typedef FSMPageData *FSMPage; /* * Number of non-leaf and leaf nodes, and nodes in total, on an FSM page. * These definitions are internal to fsmpage.c. */ #define NodesPerPage (BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - \ offsetof(FSMPageData, fp_nodes)) #define NonLeafNodesPerPage (BLCKSZ / 2 - 1) #define LeafNodesPerPage (NodesPerPage - NonLeafNodesPerPage) /* * Number of FSM "slots" on a FSM page. This is what should be used * outside fsmpage.c. */ #define SlotsPerFSMPage LeafNodesPerPage /* Prototypes for functions in fsmpage.c */ extern int fsm_search_avail(Buffer buf, uint8 min_cat, bool advancenext, bool exclusive_lock_held); extern uint8 fsm_get_avail(Page page, int slot); extern uint8 fsm_get_max_avail(Page page); extern bool fsm_set_avail(Page page, int slot, uint8 value); extern bool fsm_truncate_avail(Page page, int nslots); extern bool fsm_rebuild_page(Page page); #endif /* FSM_INTERNALS_H */