| /*------------------------------------------------------------------------- | |
| * | |
| * fsm_internals.h | |
| * internal functions for free space map | |
| * | |
| * | |
| * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group | |
| * Portions Copyright (c) 1994, Regents of the University of California | |
| * | |
| * src/include/storage/fsm_internals.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[FLEXIBLE_ARRAY_MEMBER]; | |
| } 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. | |
| */ | |
| /* | |
| * Number of FSM "slots" on a FSM page. This is what should be used | |
| * outside fsmpage.c. | |
| */ | |
| /* Prototypes for functions in fsmpage.c */ | |
| extern int fsm_search_avail(Buffer buf, uint8 minvalue, 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); | |