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12968cf408
Right now, there's only one flag, DSM_CREATE_NULL_IF_MAXSEGMENTS, which suppresses the error that would normally be thrown when the maximum number of segments already exists, instead returning NULL. It might be useful to add more flags in the future, such as one to ignore allocation errors, but I haven't done that here.
60 lines
2.0 KiB
C
60 lines
2.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* dsm.h
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* manage dynamic shared memory segments
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*
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* Portions Copyright (c) 1996-2015, 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.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef DSM_H
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#define DSM_H
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#include "storage/dsm_impl.h"
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typedef struct dsm_segment dsm_segment;
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#define DSM_CREATE_NULL_IF_MAXSEGMENTS 0x0001
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/* Startup and shutdown functions. */
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struct PGShmemHeader; /* avoid including pg_shmem.h */
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extern void dsm_cleanup_using_control_segment(dsm_handle old_control_handle);
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extern void dsm_postmaster_startup(struct PGShmemHeader *);
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extern void dsm_backend_shutdown(void);
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extern void dsm_detach_all(void);
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#ifdef EXEC_BACKEND
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extern void dsm_set_control_handle(dsm_handle h);
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#endif
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/* Functions that create, update, or remove mappings. */
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extern dsm_segment *dsm_create(Size size, int flags);
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extern dsm_segment *dsm_attach(dsm_handle h);
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extern void *dsm_resize(dsm_segment *seg, Size size);
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extern void *dsm_remap(dsm_segment *seg);
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extern void dsm_detach(dsm_segment *seg);
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/* Resource management functions. */
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extern void dsm_pin_mapping(dsm_segment *seg);
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extern void dsm_unpin_mapping(dsm_segment *seg);
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extern void dsm_pin_segment(dsm_segment *seg);
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extern dsm_segment *dsm_find_mapping(dsm_handle h);
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/* Informational functions. */
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extern void *dsm_segment_address(dsm_segment *seg);
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extern Size dsm_segment_map_length(dsm_segment *seg);
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extern dsm_handle dsm_segment_handle(dsm_segment *seg);
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/* Cleanup hooks. */
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typedef void (*on_dsm_detach_callback) (dsm_segment *, Datum arg);
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extern void on_dsm_detach(dsm_segment *seg,
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on_dsm_detach_callback function, Datum arg);
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extern void cancel_on_dsm_detach(dsm_segment *seg,
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on_dsm_detach_callback function, Datum arg);
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extern void reset_on_dsm_detach(void);
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#endif /* DSM_H */
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