greenplumn dsm 源码
greenplumn dsm 代码
文件路径：/src/include/storage/dsm.h
/*-------------------------------------------------------------------------
*
* dsm.h
* manage dynamic shared memory segments
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/dsm.h
*
*-------------------------------------------------------------------------
*/
#ifndef DSM_H
#define DSM_H
#include "storage/dsm_impl.h"
typedef struct dsm_segment dsm_segment;
#define DSM_CREATE_NULL_IF_MAXSEGMENTS 0x0001
/* A sentinel value for an invalid DSM handle. */
#define DSM_HANDLE_INVALID 0
/* Startup and shutdown functions. */
struct PGShmemHeader; /* avoid including pg_shmem.h */
extern void dsm_cleanup_using_control_segment(dsm_handle old_control_handle);
extern void dsm_postmaster_startup(struct PGShmemHeader *);
extern void dsm_backend_shutdown(void);
extern void dsm_detach_all(void);
#ifdef EXEC_BACKEND
extern void dsm_set_control_handle(dsm_handle h);
#endif
/* Functions that create or remove mappings. */
extern dsm_segment *dsm_create(Size size, int flags);
extern dsm_segment *dsm_attach(dsm_handle h);
extern void dsm_detach(dsm_segment *seg);
/* Resource management functions. */
extern void dsm_pin_mapping(dsm_segment *seg);
extern void dsm_unpin_mapping(dsm_segment *seg);
extern void dsm_pin_segment(dsm_segment *seg);
extern void dsm_unpin_segment(dsm_handle h);
extern dsm_segment *dsm_find_mapping(dsm_handle h);
/* Informational functions. */
extern void *dsm_segment_address(dsm_segment *seg);
extern Size dsm_segment_map_length(dsm_segment *seg);
extern dsm_handle dsm_segment_handle(dsm_segment *seg);
/* Cleanup hooks. */
typedef void (*on_dsm_detach_callback) (dsm_segment *, Datum arg);
extern void on_dsm_detach(dsm_segment *seg,
on_dsm_detach_callback function, Datum arg);
extern void cancel_on_dsm_detach(dsm_segment *seg,
on_dsm_detach_callback function, Datum arg);
extern void reset_on_dsm_detach(void);
#endif /* DSM_H */
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