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Diffstat (limited to 'src/include/storage/fsm_internals.h')
| -rw-r--r-- | src/include/storage/fsm_internals.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/src/include/storage/fsm_internals.h b/src/include/storage/fsm_internals.h new file mode 100644 index 0000000..0974976 --- /dev/null +++ b/src/include/storage/fsm_internals.h @@ -0,0 +1,72 @@ +/*------------------------------------------------------------------------- + * + * fsm_internals.h + * internal functions for free space map + * + * + * Portions Copyright (c) 1996-2021, 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[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. + */ +#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 */ |