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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
commit | 6eb9c5a5657d1fe77b55cc261450f3538d35a94d (patch) | |
tree | 657d8194422a5daccecfd42d654b8a245ef7b4c8 /src/include/storage/shm_toc.h | |
parent | Initial commit. (diff) | |
download | postgresql-13-6eb9c5a5657d1fe77b55cc261450f3538d35a94d.tar.xz postgresql-13-6eb9c5a5657d1fe77b55cc261450f3538d35a94d.zip |
Adding upstream version 13.4.upstream/13.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/include/storage/shm_toc.h')
-rw-r--r-- | src/include/storage/shm_toc.h | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/src/include/storage/shm_toc.h b/src/include/storage/shm_toc.h new file mode 100644 index 0000000..c3886d5 --- /dev/null +++ b/src/include/storage/shm_toc.h @@ -0,0 +1,58 @@ +/*------------------------------------------------------------------------- + * + * shm_toc.h + * shared memory segment table of contents + * + * This is intended to provide a simple way to divide a chunk of shared + * memory (probably dynamic shared memory allocated via dsm_create) into + * a number of regions and keep track of the addresses of those regions or + * key data structures within those regions. This is not intended to + * scale to a large number of keys and will perform poorly if used that + * way; if you need a large number of pointers, store them within some + * other data structure within the segment and only put the pointer to + * the data structure itself in the table of contents. + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/shm_toc.h + * + *------------------------------------------------------------------------- + */ +#ifndef SHM_TOC_H +#define SHM_TOC_H + +#include "storage/shmem.h" /* for add_size() */ + +/* shm_toc is an opaque type known only within shm_toc.c */ +typedef struct shm_toc shm_toc; + +extern shm_toc *shm_toc_create(uint64 magic, void *address, Size nbytes); +extern shm_toc *shm_toc_attach(uint64 magic, void *address); +extern void *shm_toc_allocate(shm_toc *toc, Size nbytes); +extern Size shm_toc_freespace(shm_toc *toc); +extern void shm_toc_insert(shm_toc *toc, uint64 key, void *address); +extern void *shm_toc_lookup(shm_toc *toc, uint64 key, bool noError); + +/* + * Tools for estimating how large a chunk of shared memory will be needed + * to store a TOC and its dependent objects. Note: we don't really support + * large numbers of keys, but it's convenient to declare number_of_keys + * as a Size anyway. + */ +typedef struct +{ + Size space_for_chunks; + Size number_of_keys; +} shm_toc_estimator; + +#define shm_toc_initialize_estimator(e) \ + ((e)->space_for_chunks = 0, (e)->number_of_keys = 0) +#define shm_toc_estimate_chunk(e, sz) \ + ((e)->space_for_chunks = add_size((e)->space_for_chunks, BUFFERALIGN(sz))) +#define shm_toc_estimate_keys(e, cnt) \ + ((e)->number_of_keys = add_size((e)->number_of_keys, cnt)) + +extern Size shm_toc_estimate(shm_toc_estimator *e); + +#endif /* SHM_TOC_H */ |