codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * shm_toc.h4 *	  shared memory segment table of contents5 *6 * This is intended to provide a simple way to divide a chunk of shared7 * memory (probably dynamic shared memory allocated via dsm_create) into8 * a number of regions and keep track of the addresses of those regions or9 * key data structures within those regions.  This is not intended to10 * scale to a large number of keys and will perform poorly if used that11 * way; if you need a large number of pointers, store them within some12 * other data structure within the segment and only put the pointer to13 * the data structure itself in the table of contents.14 *15 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group16 * Portions Copyright (c) 1994, Regents of the University of California17 *18 * src/include/storage/shm_toc.h19 *20 *-------------------------------------------------------------------------21 */22#ifndef SHM_TOC_H23#define SHM_TOC_H24 25#include "storage/shmem.h"		/* for add_size() */26 27/* shm_toc is an opaque type known only within shm_toc.c */28typedef struct shm_toc shm_toc;29 30extern shm_toc *shm_toc_create(uint64 magic, void *address, Size nbytes);31extern shm_toc *shm_toc_attach(uint64 magic, void *address);32extern void *shm_toc_allocate(shm_toc *toc, Size nbytes);33extern Size shm_toc_freespace(shm_toc *toc);34extern void shm_toc_insert(shm_toc *toc, uint64 key, void *address);35extern void *shm_toc_lookup(shm_toc *toc, uint64 key, bool noError);36 37/*38 * Tools for estimating how large a chunk of shared memory will be needed39 * to store a TOC and its dependent objects.  Note: we don't really support40 * large numbers of keys, but it's convenient to declare number_of_keys41 * as a Size anyway.42 */43typedef struct44{45	Size		space_for_chunks;46	Size		number_of_keys;47} shm_toc_estimator;48 49#define shm_toc_initialize_estimator(e) \50	((e)->space_for_chunks = 0, (e)->number_of_keys = 0)51#define shm_toc_estimate_chunk(e, sz) \52	((e)->space_for_chunks = add_size((e)->space_for_chunks, BUFFERALIGN(sz)))53#define shm_toc_estimate_keys(e, cnt) \54	((e)->number_of_keys = add_size((e)->number_of_keys, cnt))55 56extern Size shm_toc_estimate(shm_toc_estimator *e);57 58#endif							/* SHM_TOC_H */59