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SharedFileSet allows temporary files to be created by one backend and
then exported for read-only access by other backends, with clean-up
managed by reference counting associated with a DSM segment. This
includes changes to fd.c and buffile.c to support the new kind of
temporary file.
This will be used by an upcoming patch adding support for parallel
hash joins.
Author: Thomas Munro
Reviewed-By: Peter Geoghegan, Andres Freund, Robert Haas, Rushabh Lathia
Discussion:
https://postgr.es/m/CAEepm=2W=cOkiZxcg6qiFQP-dHUe09aqTrEMM7yJDrHMhDv_RA@mail.gmail.com
https://postgr.es/m/CAH2-WznJ_UgLux=_jTgCQ4yFz0iBntudsNKa1we3kN1BAG=88w@mail.gmail.com
46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* sharedfileset.h
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* Shared temporary file management.
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*
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*
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* Portions Copyright (c) 1996-2017, 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/sharedfilespace.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SHAREDFILESET_H
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#define SHAREDFILESET_H
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#include "storage/dsm.h"
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#include "storage/fd.h"
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#include "storage/spin.h"
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/*
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* A set of temporary files that can be shared by multiple backends.
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*/
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typedef struct SharedFileSet
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{
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pid_t creator_pid; /* PID of the creating process */
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uint32 number; /* per-PID identifier */
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slock_t mutex; /* mutex protecting the reference count */
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int refcnt; /* number of attached backends */
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int ntablespaces; /* number of tablespaces to use */
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Oid tablespaces[8]; /* OIDs of tablespaces to use. Assumes that
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* it's rare that there more than temp
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* tablespaces. */
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} SharedFileSet;
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extern void SharedFileSetInit(SharedFileSet *fileset, dsm_segment *seg);
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extern void SharedFileSetAttach(SharedFileSet *fileset, dsm_segment *seg);
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extern File SharedFileSetCreate(SharedFileSet *fileset, const char *name);
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extern File SharedFileSetOpen(SharedFileSet *fileset, const char *name);
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extern bool SharedFileSetDelete(SharedFileSet *fileset, const char *name,
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bool error_on_failure);
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extern void SharedFileSetDeleteAll(SharedFileSet *fileset);
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#endif
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