80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* dsm_impl.h
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* low-level dynamic shared memory primitives
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/dsm_impl.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef DSM_IMPL_H
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#define DSM_IMPL_H
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/* Dynamic shared memory implementations. */
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#define DSM_IMPL_POSIX 1
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#define DSM_IMPL_SYSV 2
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#define DSM_IMPL_WINDOWS 3
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#define DSM_IMPL_MMAP 4
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/*
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* Determine which dynamic shared memory implementations will be supported
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* on this platform, and which one will be the default.
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*/
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#ifdef WIN32
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#define USE_DSM_WINDOWS
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#define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_WINDOWS
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#else
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#ifdef HAVE_SHM_OPEN
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#define USE_DSM_POSIX
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#define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_POSIX
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#endif
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#define USE_DSM_SYSV
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#ifndef DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE
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#define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_SYSV
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#endif
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#define USE_DSM_MMAP
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#endif
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/* GUC. */
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extern PGDLLIMPORT int dynamic_shared_memory_type;
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extern PGDLLIMPORT int min_dynamic_shared_memory;
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/*
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* Directory for on-disk state.
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*
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* This is used by all implementations for crash recovery and by the mmap
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* implementation for storage.
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*/
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#define PG_DYNSHMEM_DIR "pg_dynshmem"
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#define PG_DYNSHMEM_MMAP_FILE_PREFIX "mmap."
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/* A "name" for a dynamic shared memory segment. */
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typedef uint32 dsm_handle;
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/* Sentinel value to use for invalid DSM handles. */
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#define DSM_HANDLE_INVALID ((dsm_handle) 0)
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/* All the shared-memory operations we know about. */
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typedef enum
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{
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DSM_OP_CREATE,
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DSM_OP_ATTACH,
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DSM_OP_DETACH,
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DSM_OP_DESTROY,
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} dsm_op;
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/* Create, attach to, detach from, resize, or destroy a segment. */
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extern bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size,
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void **impl_private, void **mapped_address, Size *mapped_size,
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int elevel);
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/* Implementation-dependent actions required to keep segment until shutdown. */
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extern void dsm_impl_pin_segment(dsm_handle handle, void *impl_private,
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void **impl_private_pm_handle);
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extern void dsm_impl_unpin_segment(dsm_handle handle, void **impl_private);
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#endif /* DSM_IMPL_H */
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