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Diffstat (limited to 'src/include/utils/dsa.h')
| -rw-r--r-- | src/include/utils/dsa.h | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/include/utils/dsa.h b/src/include/utils/dsa.h new file mode 100644 index 00000000000..4ef5c241c91 --- /dev/null +++ b/src/include/utils/dsa.h @@ -0,0 +1,108 @@ +/*------------------------------------------------------------------------- + * + * dsa.h + * Dynamic shared memory areas. + * + * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/include/utils/dsa.h + * + *------------------------------------------------------------------------- + */ +#ifndef DSA_H +#define DSA_H + +#include "postgres.h" + +#include "port/atomics.h" +#include "storage/dsm.h" + +/* The opaque type used for an area. */ +struct dsa_area; +typedef struct dsa_area dsa_area; + +/* + * If this system doesn't support atomic operations on 64 bit values then + * we fall back to 32 bit dsa_pointer. For testing purposes, + * USE_SMALL_DSA_POINTER can be defined to force the use of 32 bit + * dsa_pointer even on systems that support 64 bit atomics. + */ +#ifndef PG_HAVE_ATOMIC_U64_SUPPORT +#define SIZEOF_DSA_POINTER 4 +#else +#ifdef USE_SMALL_DSA_POINTER +#define SIZEOF_DSA_POINTER 4 +#else +#define SIZEOF_DSA_POINTER 8 +#endif +#endif + +/* + * The type of 'relative pointers' to memory allocated by a dynamic shared + * area. dsa_pointer values can be shared with other processes, but must be + * converted to backend-local pointers before they can be dereferenced. See + * dsa_get_address. Also, an atomic version and appropriately sized atomic + * operations. + */ +#if DSA_POINTER_SIZEOF == 4 +typedef uint32 dsa_pointer; +typedef pg_atomic_uint32 dsa_pointer_atomic; +#define dsa_pointer_atomic_init pg_atomic_init_u32 +#define dsa_pointer_atomic_read pg_atomic_read_u32 +#define dsa_pointer_atomic_write pg_atomic_write_u32 +#define dsa_pointer_atomic_fetch_add pg_atomic_fetch_add_u32 +#define dsa_pointer_atomic_compare_exchange pg_atomic_compare_exchange_u32 +#else +typedef uint64 dsa_pointer; +typedef pg_atomic_uint64 dsa_pointer_atomic; +#define dsa_pointer_atomic_init pg_atomic_init_u64 +#define dsa_pointer_atomic_read pg_atomic_read_u64 +#define dsa_pointer_atomic_write pg_atomic_write_u64 +#define dsa_pointer_atomic_fetch_add pg_atomic_fetch_add_u64 +#define dsa_pointer_atomic_compare_exchange pg_atomic_compare_exchange_u64 +#endif + +/* A sentinel value for dsa_pointer used to indicate failure to allocate. */ +#define InvalidDsaPointer ((dsa_pointer) 0) + +/* Check if a dsa_pointer value is valid. */ +#define DsaPointerIsValid(x) ((x) != InvalidDsaPointer) + +/* + * The type used for dsa_area handles. dsa_handle values can be shared with + * other processes, so that they can attach to them. This provides a way to + * share allocated storage with other processes. + * + * The handle for a dsa_area is currently implemented as the dsm_handle + * for the first DSM segment backing this dynamic storage area, but client + * code shouldn't assume that is true. + */ +typedef dsm_handle dsa_handle; + +extern void dsa_startup(void); + +extern dsa_area *dsa_create(int tranche_id, const char *tranche_name); +extern dsa_area *dsa_create_in_place(void *place, Size size, + int tranche_id, const char *tranche_name, + dsm_segment *segment); +extern dsa_area *dsa_attach(dsa_handle handle); +extern dsa_area *dsa_attach_in_place(void *place, dsm_segment *segment); +extern void dsa_release_in_place(void *place); +extern void dsa_on_dsm_detach_release_in_place(dsm_segment *, Datum); +extern void dsa_on_shmem_exit_release_in_place(int, Datum); +extern void dsa_pin_mapping(dsa_area *area); +extern void dsa_detach(dsa_area *area); +extern void dsa_pin(dsa_area *area); +extern void dsa_unpin(dsa_area *area); +extern void dsa_set_size_limit(dsa_area *area, Size limit); +extern Size dsa_minimum_size(void); +extern dsa_handle dsa_get_handle(dsa_area *area); +extern dsa_pointer dsa_allocate(dsa_area *area, Size size); +extern void dsa_free(dsa_area *area, dsa_pointer dp); +extern void *dsa_get_address(dsa_area *area, dsa_pointer dp); +extern void dsa_trim(dsa_area *area); +extern void dsa_dump(dsa_area *area); + +#endif /* DSA_H */ |