mirror of
https://git.postgresql.org/git/postgresql.git
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1156 lines
28 KiB
C
1156 lines
28 KiB
C
/*-------------------------------------------------------------------------
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*
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* fd.c
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* Virtual file descriptor code.
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.65 2000/10/28 16:20:56 vadim Exp $
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*
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* NOTES:
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*
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* This code manages a cache of 'virtual' file descriptors (VFDs).
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* The server opens many file descriptors for a variety of reasons,
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* including base tables, scratch files (e.g., sort and hash spool
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* files), and random calls to C library routines like system(3); it
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* is quite easy to exceed system limits on the number of open files a
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* single process can have. (This is around 256 on many modern
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* operating systems, but can be as low as 32 on others.)
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*
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* VFDs are managed as an LRU pool, with actual OS file descriptors
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* being opened and closed as needed. Obviously, if a routine is
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* opened using these interfaces, all subsequent operations must also
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* be through these interfaces (the File type is not a real file
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* descriptor).
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*
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* For this scheme to work, most (if not all) routines throughout the
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* server should use these interfaces instead of calling the C library
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* routines (e.g., open(2) and fopen(3)) themselves. Otherwise, we
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* may find ourselves short of real file descriptors anyway.
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*
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* This file used to contain a bunch of stuff to support RAID levels 0
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* (jbod), 1 (duplex) and 5 (xor parity). That stuff is all gone
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* because the parallel query processing code that called it is all
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* gone. If you really need it you could get it from the original
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* POSTGRES source.
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <sys/types.h>
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#include <sys/file.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "miscadmin.h"
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#include "storage/fd.h"
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/*
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* Problem: Postgres does a system(ld...) to do dynamic loading.
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* This will open several extra files in addition to those used by
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* Postgres. We need to guarantee that there are file descriptors free
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* for ld to use.
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*
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* The current solution is to limit the number of file descriptors
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* that this code will allocate at one time: it leaves RESERVE_FOR_LD free.
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*
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* (Even though most dynamic loaders now use dlopen(3) or the
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* equivalent, the OS must still open several files to perform the
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* dynamic loading. Keep this here.)
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*/
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#ifndef RESERVE_FOR_LD
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#define RESERVE_FOR_LD 10
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#endif
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/*
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* We need to ensure that we have at least some file descriptors
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* available to postgreSQL after we've reserved the ones for LD,
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* so we set that value here.
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*
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* I think 10 is an appropriate value so that's what it'll be
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* for now.
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*/
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#ifndef FD_MINFREE
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#define FD_MINFREE 10
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#endif
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/* Debugging.... */
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#ifdef FDDEBUG
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#define DO_DB(A) A
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#else
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#define DO_DB(A) /* A */
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#endif
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#define VFD_CLOSED (-1)
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#define FileIsValid(file) \
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((file) > 0 && (file) < (int) SizeVfdCache && VfdCache[file].fileName != NULL)
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#define FileIsNotOpen(file) (VfdCache[file].fd == VFD_CLOSED)
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#define FileUnknownPos (-1)
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typedef struct vfd
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{
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signed short fd; /* current FD, or VFD_CLOSED if none */
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unsigned short fdstate; /* bitflags for VFD's state */
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/* these are the assigned bits in fdstate: */
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#define FD_DIRTY (1 << 0)/* written to, but not yet fsync'd */
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#define FD_TEMPORARY (1 << 1)/* should be unlinked when closed */
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File nextFree; /* link to next free VFD, if in freelist */
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File lruMoreRecently;/* doubly linked recency-of-use list */
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File lruLessRecently;
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long seekPos; /* current logical file position */
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char *fileName; /* name of file, or NULL for unused VFD */
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/* NB: fileName is malloc'd, and must be free'd when closing the VFD */
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int fileFlags; /* open(2) flags for opening the file */
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int fileMode; /* mode to pass to open(2) */
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} Vfd;
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/*
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* Virtual File Descriptor array pointer and size. This grows as
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* needed. 'File' values are indexes into this array.
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* Note that VfdCache[0] is not a usable VFD, just a list header.
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*/
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static Vfd *VfdCache;
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static Size SizeVfdCache = 0;
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/*
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* Number of file descriptors known to be in use by VFD entries.
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*/
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static int nfile = 0;
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/*
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* List of stdio FILEs opened with AllocateFile.
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*
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* Since we don't want to encourage heavy use of AllocateFile, it seems
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* OK to put a pretty small maximum limit on the number of simultaneously
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* allocated files.
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*/
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#define MAX_ALLOCATED_FILES 32
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static int numAllocatedFiles = 0;
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static FILE *allocatedFiles[MAX_ALLOCATED_FILES];
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/*
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* Number of temporary files opened during the current transaction;
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* this is used in generation of tempfile names.
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*/
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static long tempFileCounter = 0;
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/*--------------------
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*
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* Private Routines
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*
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* Delete - delete a file from the Lru ring
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* LruDelete - remove a file from the Lru ring and close its FD
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* Insert - put a file at the front of the Lru ring
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* LruInsert - put a file at the front of the Lru ring and open it
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* ReleaseLruFile - Release an fd by closing the last entry in the Lru ring
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* AllocateVfd - grab a free (or new) file record (from VfdArray)
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* FreeVfd - free a file record
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*
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* The Least Recently Used ring is a doubly linked list that begins and
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* ends on element zero. Element zero is special -- it doesn't represent
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* a file and its "fd" field always == VFD_CLOSED. Element zero is just an
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* anchor that shows us the beginning/end of the ring.
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* Only VFD elements that are currently really open (have an FD assigned) are
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* in the Lru ring. Elements that are "virtually" open can be recognized
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* by having a non-null fileName field.
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*
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* example:
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*
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* /--less----\ /---------\
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* v \ v \
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* #0 --more---> LeastRecentlyUsed --more-\ \
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* ^\ | |
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* \\less--> MostRecentlyUsedFile <---/ |
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* \more---/ \--less--/
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*
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*--------------------
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*/
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static void Delete(File file);
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static void LruDelete(File file);
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static void Insert(File file);
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static int LruInsert(File file);
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static bool ReleaseLruFile(void);
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static File AllocateVfd(void);
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static void FreeVfd(File file);
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static int FileAccess(File file);
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static File fileNameOpenFile(FileName fileName, int fileFlags, int fileMode);
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static char *filepath(char *filename);
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static long pg_nofile(void);
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/*
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* pg_fsync --- same as fsync except does nothing if -F switch was given
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*/
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int
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pg_fsync(int fd)
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{
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if (enableFsync)
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return fsync(fd);
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else
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return 0;
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}
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/*
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* BasicOpenFile --- same as open(2) except can free other FDs if needed
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*
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* This is exported for use by places that really want a plain kernel FD,
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* but need to be proof against running out of FDs. Once an FD has been
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* successfully returned, it is the caller's responsibility to ensure that
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* it will not be leaked on elog()! Most users should *not* call this
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* routine directly, but instead use the VFD abstraction level, which
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* provides protection against descriptor leaks as well as management of
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* files that need to be open for more than a short period of time.
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*
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* Ideally this should be the *only* direct call of open() in the backend.
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* In practice, the postmaster calls open() directly, and there are some
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* direct open() calls done early in backend startup. Those are OK since
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* this module wouldn't have any open files to close at that point anyway.
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*/
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int
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BasicOpenFile(FileName fileName, int fileFlags, int fileMode)
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{
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int fd;
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tryAgain:
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fd = open(fileName, fileFlags, fileMode);
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if (fd >= 0)
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return fd; /* success! */
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if (errno == EMFILE || errno == ENFILE)
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{
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int save_errno = errno;
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DO_DB(elog(DEBUG, "BasicOpenFile: not enough descs, retry, er= %d",
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errno));
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errno = 0;
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if (ReleaseLruFile())
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goto tryAgain;
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errno = save_errno;
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}
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return -1; /* failure */
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}
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/*
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* pg_nofile: determine number of filedescriptors that fd.c is allowed to use
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*/
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static long
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pg_nofile(void)
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{
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static long no_files = 0;
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if (no_files == 0)
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{
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/* need do this calculation only once */
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#ifndef HAVE_SYSCONF
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no_files = (long) NOFILE;
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#else
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no_files = sysconf(_SC_OPEN_MAX);
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if (no_files == -1)
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{
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elog(DEBUG, "pg_nofile: Unable to get _SC_OPEN_MAX using sysconf(); using %d", NOFILE);
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no_files = (long) NOFILE;
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}
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#endif
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if ((no_files - RESERVE_FOR_LD) < FD_MINFREE)
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elog(FATAL, "pg_nofile: insufficient File Descriptors in postmaster to start backend (%ld).\n"
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" O/S allows %ld, Postmaster reserves %d, We need %d (MIN) after that.",
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no_files - RESERVE_FOR_LD, no_files, RESERVE_FOR_LD, FD_MINFREE);
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no_files -= RESERVE_FOR_LD;
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}
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return no_files;
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}
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#if defined(FDDEBUG)
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static void
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_dump_lru(void)
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{
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int mru = VfdCache[0].lruLessRecently;
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Vfd *vfdP = &VfdCache[mru];
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char buf[2048];
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sprintf(buf, "LRU: MOST %d ", mru);
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while (mru != 0)
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{
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mru = vfdP->lruLessRecently;
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vfdP = &VfdCache[mru];
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sprintf(buf + strlen(buf), "%d ", mru);
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}
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sprintf(buf + strlen(buf), "LEAST");
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elog(DEBUG, buf);
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}
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#endif /* FDDEBUG */
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static void
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Delete(File file)
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{
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Vfd *vfdP;
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Assert(file != 0);
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DO_DB(elog(DEBUG, "Delete %d (%s)",
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file, VfdCache[file].fileName));
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DO_DB(_dump_lru());
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vfdP = &VfdCache[file];
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VfdCache[vfdP->lruLessRecently].lruMoreRecently = vfdP->lruMoreRecently;
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VfdCache[vfdP->lruMoreRecently].lruLessRecently = vfdP->lruLessRecently;
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DO_DB(_dump_lru());
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}
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static void
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LruDelete(File file)
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{
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Vfd *vfdP;
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int returnValue;
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Assert(file != 0);
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DO_DB(elog(DEBUG, "LruDelete %d (%s)",
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file, VfdCache[file].fileName));
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vfdP = &VfdCache[file];
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/* delete the vfd record from the LRU ring */
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Delete(file);
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/* save the seek position */
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vfdP->seekPos = (long) lseek(vfdP->fd, 0L, SEEK_CUR);
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Assert(vfdP->seekPos != -1);
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/* if we have written to the file, sync it before closing */
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if (vfdP->fdstate & FD_DIRTY)
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{
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returnValue = pg_fsync(vfdP->fd);
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Assert(returnValue != -1);
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vfdP->fdstate &= ~FD_DIRTY;
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}
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/* close the file */
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returnValue = close(vfdP->fd);
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Assert(returnValue != -1);
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--nfile;
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vfdP->fd = VFD_CLOSED;
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}
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static void
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Insert(File file)
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{
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Vfd *vfdP;
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Assert(file != 0);
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DO_DB(elog(DEBUG, "Insert %d (%s)",
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file, VfdCache[file].fileName));
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DO_DB(_dump_lru());
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vfdP = &VfdCache[file];
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vfdP->lruMoreRecently = 0;
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vfdP->lruLessRecently = VfdCache[0].lruLessRecently;
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VfdCache[0].lruLessRecently = file;
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VfdCache[vfdP->lruLessRecently].lruMoreRecently = file;
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DO_DB(_dump_lru());
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}
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static int
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LruInsert(File file)
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{
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Vfd *vfdP;
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int returnValue;
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Assert(file != 0);
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DO_DB(elog(DEBUG, "LruInsert %d (%s)",
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file, VfdCache[file].fileName));
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vfdP = &VfdCache[file];
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if (FileIsNotOpen(file))
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{
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while (nfile + numAllocatedFiles >= pg_nofile())
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{
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if (! ReleaseLruFile())
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break;
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}
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/*
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* The open could still fail for lack of file descriptors, eg due
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* to overall system file table being full. So, be prepared to
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* release another FD if necessary...
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*/
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vfdP->fd = BasicOpenFile(vfdP->fileName, vfdP->fileFlags,
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vfdP->fileMode);
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if (vfdP->fd < 0)
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{
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DO_DB(elog(DEBUG, "RE_OPEN FAILED: %d", errno));
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return vfdP->fd;
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}
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else
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{
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DO_DB(elog(DEBUG, "RE_OPEN SUCCESS"));
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++nfile;
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}
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/* seek to the right position */
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if (vfdP->seekPos != 0L)
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{
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returnValue = lseek(vfdP->fd, vfdP->seekPos, SEEK_SET);
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Assert(returnValue != -1);
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}
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}
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/*
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* put it at the head of the Lru ring
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*/
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Insert(file);
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return 0;
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}
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static bool
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ReleaseLruFile(void)
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{
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DO_DB(elog(DEBUG, "ReleaseLruFile. Opened %d", nfile));
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if (nfile > 0)
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{
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/*
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* There are opened files and so there should be at least one used
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* vfd in the ring.
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*/
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Assert(VfdCache[0].lruMoreRecently != 0);
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LruDelete(VfdCache[0].lruMoreRecently);
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return true; /* freed a file */
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}
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return false; /* no files available to free */
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}
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static File
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AllocateVfd(void)
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{
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Index i;
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File file;
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DO_DB(elog(DEBUG, "AllocateVfd. Size %d", SizeVfdCache));
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if (SizeVfdCache == 0)
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{
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/* initialize header entry first time through */
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VfdCache = (Vfd *) malloc(sizeof(Vfd));
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Assert(VfdCache != NULL);
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MemSet((char *) &(VfdCache[0]), 0, sizeof(Vfd));
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VfdCache->fd = VFD_CLOSED;
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SizeVfdCache = 1;
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|
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/*
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* register proc-exit call to ensure temp files are dropped at
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* exit
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*/
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on_proc_exit(AtEOXact_Files, 0);
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}
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if (VfdCache[0].nextFree == 0)
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{
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/*
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* The free list is empty so it is time to increase the size of
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* the array. We choose to double it each time this happens.
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* However, there's not much point in starting *real* small.
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*/
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Size newCacheSize = SizeVfdCache * 2;
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if (newCacheSize < 32)
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newCacheSize = 32;
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VfdCache = (Vfd *) realloc(VfdCache, sizeof(Vfd) * newCacheSize);
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Assert(VfdCache != NULL);
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/*
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* Initialize the new entries and link them into the free list.
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*/
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for (i = SizeVfdCache; i < newCacheSize; i++)
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{
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MemSet((char *) &(VfdCache[i]), 0, sizeof(Vfd));
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VfdCache[i].nextFree = i + 1;
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VfdCache[i].fd = VFD_CLOSED;
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}
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VfdCache[newCacheSize - 1].nextFree = 0;
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VfdCache[0].nextFree = SizeVfdCache;
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/*
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* Record the new size
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*/
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SizeVfdCache = newCacheSize;
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}
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file = VfdCache[0].nextFree;
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VfdCache[0].nextFree = VfdCache[file].nextFree;
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return file;
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}
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|
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static void
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FreeVfd(File file)
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{
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Vfd *vfdP = &VfdCache[file];
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DO_DB(elog(DEBUG, "FreeVfd: %d (%s)",
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file, vfdP->fileName ? vfdP->fileName : ""));
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|
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if (vfdP->fileName != NULL)
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{
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free(vfdP->fileName);
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vfdP->fileName = NULL;
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}
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|
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vfdP->nextFree = VfdCache[0].nextFree;
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VfdCache[0].nextFree = file;
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}
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|
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/* filepath()
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|
* Convert given pathname to absolute.
|
|
*
|
|
* (Generally, this isn't actually necessary, considering that we
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|
* should be cd'd into the database directory. Presently it is only
|
|
* necessary to do it in "bootstrap" mode. Maybe we should change
|
|
* bootstrap mode to do the cd, and save a few cycles/bytes here.)
|
|
*/
|
|
static char *
|
|
filepath(char *filename)
|
|
{
|
|
char *buf;
|
|
int len;
|
|
|
|
/* Not an absolute path name? Then fill in with database path... */
|
|
if (*filename != SEP_CHAR)
|
|
{
|
|
len = strlen(DatabasePath) + strlen(filename) + 2;
|
|
buf = (char *) palloc(len);
|
|
sprintf(buf, "%s%c%s", DatabasePath, SEP_CHAR, filename);
|
|
}
|
|
else
|
|
{
|
|
buf = (char *) palloc(strlen(filename) + 1);
|
|
strcpy(buf, filename);
|
|
}
|
|
|
|
#ifdef FILEDEBUG
|
|
printf("filepath: path is %s\n", buf);
|
|
#endif
|
|
|
|
return buf;
|
|
}
|
|
|
|
static int
|
|
FileAccess(File file)
|
|
{
|
|
int returnValue;
|
|
|
|
DO_DB(elog(DEBUG, "FileAccess %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
|
|
/*
|
|
* Is the file open? If not, open it and put it at the head of the
|
|
* LRU ring (possibly closing the least recently used file to get an
|
|
* FD).
|
|
*/
|
|
|
|
if (FileIsNotOpen(file))
|
|
{
|
|
returnValue = LruInsert(file);
|
|
if (returnValue != 0)
|
|
return returnValue;
|
|
}
|
|
else if (VfdCache[0].lruLessRecently != file)
|
|
{
|
|
|
|
/*
|
|
* We now know that the file is open and that it is not the last
|
|
* one accessed, so we need to move it to the head of the Lru
|
|
* ring.
|
|
*/
|
|
|
|
Delete(file);
|
|
Insert(file);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Called when we get a shared invalidation message on some relation.
|
|
*/
|
|
#ifdef NOT_USED
|
|
void
|
|
FileInvalidate(File file)
|
|
{
|
|
Assert(FileIsValid(file));
|
|
if (!FileIsNotOpen(file))
|
|
LruDelete(file);
|
|
}
|
|
|
|
#endif
|
|
|
|
static File
|
|
fileNameOpenFile(FileName fileName,
|
|
int fileFlags,
|
|
int fileMode)
|
|
{
|
|
File file;
|
|
Vfd *vfdP;
|
|
|
|
if (fileName == NULL)
|
|
elog(ERROR, "fileNameOpenFile: NULL fname");
|
|
|
|
DO_DB(elog(DEBUG, "fileNameOpenFile: %s %x %o",
|
|
fileName, fileFlags, fileMode));
|
|
|
|
file = AllocateVfd();
|
|
vfdP = &VfdCache[file];
|
|
|
|
while (nfile + numAllocatedFiles >= pg_nofile())
|
|
{
|
|
if (! ReleaseLruFile())
|
|
break;
|
|
}
|
|
|
|
vfdP->fd = BasicOpenFile(fileName, fileFlags, fileMode);
|
|
|
|
if (vfdP->fd < 0)
|
|
{
|
|
FreeVfd(file);
|
|
return -1;
|
|
}
|
|
++nfile;
|
|
DO_DB(elog(DEBUG, "fileNameOpenFile: success %d",
|
|
vfdP->fd));
|
|
|
|
Insert(file);
|
|
|
|
vfdP->fileName = malloc(strlen(fileName) + 1);
|
|
strcpy(vfdP->fileName, fileName);
|
|
|
|
vfdP->fileFlags = fileFlags & ~(O_TRUNC | O_EXCL);
|
|
vfdP->fileMode = fileMode;
|
|
vfdP->seekPos = 0;
|
|
vfdP->fdstate = 0x0;
|
|
|
|
return file;
|
|
}
|
|
|
|
/*
|
|
* open a file in the database directory ($PGDATA/base/...)
|
|
*/
|
|
File
|
|
FileNameOpenFile(FileName fileName, int fileFlags, int fileMode)
|
|
{
|
|
File fd;
|
|
char *fname;
|
|
|
|
fname = filepath(fileName);
|
|
fd = fileNameOpenFile(fname, fileFlags, fileMode);
|
|
pfree(fname);
|
|
return fd;
|
|
}
|
|
|
|
/*
|
|
* open a file in an arbitrary directory
|
|
*/
|
|
File
|
|
PathNameOpenFile(FileName fileName, int fileFlags, int fileMode)
|
|
{
|
|
return fileNameOpenFile(fileName, fileFlags, fileMode);
|
|
}
|
|
|
|
/*
|
|
* Open a temporary file that will disappear when we close it.
|
|
*
|
|
* This routine takes care of generating an appropriate tempfile name.
|
|
* There's no need to pass in fileFlags or fileMode either, since only
|
|
* one setting makes any sense for a temp file.
|
|
*/
|
|
File
|
|
OpenTemporaryFile(void)
|
|
{
|
|
char tempfilename[64];
|
|
File file;
|
|
|
|
/*
|
|
* Generate a tempfile name that's unique within the current
|
|
* transaction
|
|
*/
|
|
snprintf(tempfilename, sizeof(tempfilename),
|
|
"pg_sorttemp%d.%ld", MyProcPid, tempFileCounter++);
|
|
|
|
/* Open the file */
|
|
file = FileNameOpenFile(tempfilename,
|
|
O_RDWR | O_CREAT | O_TRUNC | PG_BINARY, 0600);
|
|
if (file <= 0)
|
|
elog(ERROR, "Failed to create temporary file %s", tempfilename);
|
|
|
|
/* Mark it for deletion at close or EOXact */
|
|
VfdCache[file].fdstate |= FD_TEMPORARY;
|
|
|
|
return file;
|
|
}
|
|
|
|
/*
|
|
* close a file when done with it
|
|
*/
|
|
void
|
|
FileClose(File file)
|
|
{
|
|
int returnValue;
|
|
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileClose: %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
|
|
if (!FileIsNotOpen(file))
|
|
{
|
|
|
|
/* remove the file from the lru ring */
|
|
Delete(file);
|
|
|
|
/* if we did any writes, sync the file before closing */
|
|
if (VfdCache[file].fdstate & FD_DIRTY)
|
|
{
|
|
returnValue = pg_fsync(VfdCache[file].fd);
|
|
Assert(returnValue != -1);
|
|
VfdCache[file].fdstate &= ~FD_DIRTY;
|
|
}
|
|
|
|
/* close the file */
|
|
returnValue = close(VfdCache[file].fd);
|
|
Assert(returnValue != -1);
|
|
|
|
--nfile;
|
|
VfdCache[file].fd = VFD_CLOSED;
|
|
}
|
|
|
|
/*
|
|
* Delete the file if it was temporary
|
|
*/
|
|
if (VfdCache[file].fdstate & FD_TEMPORARY)
|
|
unlink(VfdCache[file].fileName);
|
|
|
|
/*
|
|
* Return the Vfd slot to the free list
|
|
*/
|
|
FreeVfd(file);
|
|
}
|
|
|
|
/*
|
|
* close a file and forcibly delete the underlying Unix file
|
|
*/
|
|
void
|
|
FileUnlink(File file)
|
|
{
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileUnlink: %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
|
|
/* force FileClose to delete it */
|
|
VfdCache[file].fdstate |= FD_TEMPORARY;
|
|
|
|
FileClose(file);
|
|
}
|
|
|
|
int
|
|
FileRead(File file, char *buffer, int amount)
|
|
{
|
|
int returnCode;
|
|
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileRead: %d (%s) %d %p",
|
|
file, VfdCache[file].fileName, amount, buffer));
|
|
|
|
FileAccess(file);
|
|
returnCode = read(VfdCache[file].fd, buffer, amount);
|
|
if (returnCode > 0)
|
|
VfdCache[file].seekPos += returnCode;
|
|
else
|
|
VfdCache[file].seekPos = FileUnknownPos;
|
|
|
|
return returnCode;
|
|
}
|
|
|
|
int
|
|
FileWrite(File file, char *buffer, int amount)
|
|
{
|
|
int returnCode;
|
|
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileWrite: %d (%s) %d %p",
|
|
file, VfdCache[file].fileName, amount, buffer));
|
|
|
|
FileAccess(file);
|
|
returnCode = write(VfdCache[file].fd, buffer, amount);
|
|
if (returnCode > 0)
|
|
{
|
|
VfdCache[file].seekPos += returnCode;
|
|
#ifndef XLOG
|
|
/* mark the file as needing fsync */
|
|
VfdCache[file].fdstate |= FD_DIRTY;
|
|
#endif
|
|
}
|
|
else
|
|
VfdCache[file].seekPos = FileUnknownPos;
|
|
|
|
return returnCode;
|
|
}
|
|
|
|
long
|
|
FileSeek(File file, long offset, int whence)
|
|
{
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileSeek: %d (%s) %ld %d",
|
|
file, VfdCache[file].fileName, offset, whence));
|
|
|
|
if (FileIsNotOpen(file))
|
|
{
|
|
switch (whence)
|
|
{
|
|
case SEEK_SET:
|
|
if (offset < 0)
|
|
elog(ERROR, "FileSeek: invalid offset: %ld", offset);
|
|
VfdCache[file].seekPos = offset;
|
|
break;
|
|
case SEEK_CUR:
|
|
VfdCache[file].seekPos += offset;
|
|
break;
|
|
case SEEK_END:
|
|
FileAccess(file);
|
|
VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
|
|
break;
|
|
default:
|
|
elog(ERROR, "FileSeek: invalid whence: %d", whence);
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
switch (whence)
|
|
{
|
|
case SEEK_SET:
|
|
if (offset < 0)
|
|
elog(ERROR, "FileSeek: invalid offset: %ld", offset);
|
|
if (VfdCache[file].seekPos != offset)
|
|
VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
|
|
break;
|
|
case SEEK_CUR:
|
|
if (offset != 0 || VfdCache[file].seekPos == FileUnknownPos)
|
|
VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
|
|
break;
|
|
case SEEK_END:
|
|
VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
|
|
break;
|
|
default:
|
|
elog(ERROR, "FileSeek: invalid whence: %d", whence);
|
|
break;
|
|
}
|
|
}
|
|
return VfdCache[file].seekPos;
|
|
}
|
|
|
|
/*
|
|
* XXX not actually used but here for completeness
|
|
*/
|
|
#ifdef NOT_USED
|
|
long
|
|
FileTell(File file)
|
|
{
|
|
Assert(FileIsValid(file));
|
|
DO_DB(elog(DEBUG, "FileTell %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
return VfdCache[file].seekPos;
|
|
}
|
|
|
|
#endif
|
|
|
|
int
|
|
FileTruncate(File file, long offset)
|
|
{
|
|
int returnCode;
|
|
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileTruncate %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
|
|
FileSync(file);
|
|
FileAccess(file);
|
|
returnCode = ftruncate(VfdCache[file].fd, (size_t) offset);
|
|
return returnCode;
|
|
}
|
|
|
|
/*
|
|
* FileSync --- if a file is marked as dirty, fsync it.
|
|
*
|
|
* The FD_DIRTY bit is slightly misnamed: it doesn't mean that we need to
|
|
* write the file, but that we *have* written it and need to execute an
|
|
* fsync() to ensure the changes are down on disk before we mark the current
|
|
* transaction committed.
|
|
*
|
|
* FD_DIRTY is set by FileWrite or by an explicit FileMarkDirty() call.
|
|
* It is cleared after successfully fsync'ing the file. FileClose() will
|
|
* fsync a dirty File that is about to be closed, since there will be no
|
|
* other place to remember the need to fsync after the VFD is gone.
|
|
*
|
|
* Note that the DIRTY bit is logically associated with the actual disk file,
|
|
* not with any particular kernel FD we might have open for it. We assume
|
|
* that fsync will force out any dirty buffers for that file, whether or not
|
|
* they were written through the FD being used for the fsync call --- they
|
|
* might even have been written by some other backend!
|
|
*
|
|
* Note also that LruDelete currently fsyncs a dirty file that it is about
|
|
* to close the kernel file descriptor for. The idea there is to avoid
|
|
* having to re-open the kernel descriptor later. But it's not real clear
|
|
* that this is a performance win; we could end up fsyncing the same file
|
|
* multiple times in a transaction, which would probably cost more time
|
|
* than is saved by avoiding an open() call. This should be studied.
|
|
*
|
|
* This routine used to think it could skip the fsync if the file is
|
|
* physically closed, but that is now WRONG; see comments for FileMarkDirty.
|
|
*/
|
|
int
|
|
FileSync(File file)
|
|
{
|
|
int returnCode;
|
|
|
|
Assert(FileIsValid(file));
|
|
|
|
if (!(VfdCache[file].fdstate & FD_DIRTY))
|
|
{
|
|
/* Need not sync if file is not dirty. */
|
|
returnCode = 0;
|
|
}
|
|
else if (!enableFsync)
|
|
{
|
|
/* Don't force the file open if pg_fsync isn't gonna sync it. */
|
|
returnCode = 0;
|
|
VfdCache[file].fdstate &= ~FD_DIRTY;
|
|
}
|
|
else
|
|
{
|
|
|
|
/*
|
|
* We don't use FileAccess() because we don't want to force the
|
|
* file to the front of the LRU ring; we aren't expecting to
|
|
* access it again soon.
|
|
*/
|
|
if (FileIsNotOpen(file))
|
|
{
|
|
returnCode = LruInsert(file);
|
|
if (returnCode != 0)
|
|
return returnCode;
|
|
}
|
|
returnCode = pg_fsync(VfdCache[file].fd);
|
|
if (returnCode == 0)
|
|
VfdCache[file].fdstate &= ~FD_DIRTY;
|
|
}
|
|
|
|
return returnCode;
|
|
}
|
|
|
|
/*
|
|
* FileMarkDirty --- mark a file as needing fsync at transaction commit.
|
|
*
|
|
* Since FileWrite marks the file dirty, this routine is not needed in
|
|
* normal use. It is called when the buffer manager detects that some other
|
|
* backend has written out a shared buffer that this backend dirtied (but
|
|
* didn't write) in the current xact. In that scenario, we need to fsync
|
|
* the file before we can commit. We cannot assume that the other backend
|
|
* has fsync'd the file yet; we need to do our own fsync to ensure that
|
|
* (a) the disk page is written and (b) this backend's commit is delayed
|
|
* until the write is complete.
|
|
*
|
|
* Note we are assuming that an fsync issued by this backend will write
|
|
* kernel disk buffers that were dirtied by another backend. Furthermore,
|
|
* it doesn't matter whether we currently have the file physically open;
|
|
* we must fsync even if we have to re-open the file to do it.
|
|
*/
|
|
void
|
|
FileMarkDirty(File file)
|
|
{
|
|
Assert(FileIsValid(file));
|
|
|
|
DO_DB(elog(DEBUG, "FileMarkDirty: %d (%s)",
|
|
file, VfdCache[file].fileName));
|
|
|
|
VfdCache[file].fdstate |= FD_DIRTY;
|
|
}
|
|
|
|
|
|
/*
|
|
* Routines that want to use stdio (ie, FILE*) should use AllocateFile
|
|
* rather than plain fopen(). This lets fd.c deal with freeing FDs if
|
|
* necessary to open the file. When done, call FreeFile rather than fclose.
|
|
*
|
|
* Note that files that will be open for any significant length of time
|
|
* should NOT be handled this way, since they cannot share kernel file
|
|
* descriptors with other files; there is grave risk of running out of FDs
|
|
* if anyone locks down too many FDs. Most callers of this routine are
|
|
* simply reading a config file that they will read and close immediately.
|
|
*
|
|
* fd.c will automatically close all files opened with AllocateFile at
|
|
* transaction commit or abort; this prevents FD leakage if a routine
|
|
* that calls AllocateFile is terminated prematurely by elog(ERROR).
|
|
*
|
|
* Ideally this should be the *only* direct call of fopen() in the backend.
|
|
*/
|
|
|
|
FILE *
|
|
AllocateFile(char *name, char *mode)
|
|
{
|
|
FILE *file;
|
|
|
|
DO_DB(elog(DEBUG, "AllocateFile: Allocated %d", numAllocatedFiles));
|
|
|
|
if (numAllocatedFiles >= MAX_ALLOCATED_FILES)
|
|
elog(ERROR, "AllocateFile: too many private FDs demanded");
|
|
|
|
TryAgain:
|
|
if ((file = fopen(name, mode)) != NULL)
|
|
{
|
|
allocatedFiles[numAllocatedFiles++] = file;
|
|
return file;
|
|
}
|
|
|
|
if (errno == EMFILE || errno == ENFILE)
|
|
{
|
|
int save_errno = errno;
|
|
|
|
DO_DB(elog(DEBUG, "AllocateFile: not enough descs, retry, er= %d",
|
|
errno));
|
|
errno = 0;
|
|
if (ReleaseLruFile())
|
|
goto TryAgain;
|
|
errno = save_errno;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
void
|
|
FreeFile(FILE *file)
|
|
{
|
|
int i;
|
|
|
|
DO_DB(elog(DEBUG, "FreeFile: Allocated %d", numAllocatedFiles));
|
|
|
|
/* Remove file from list of allocated files, if it's present */
|
|
for (i = numAllocatedFiles; --i >= 0;)
|
|
{
|
|
if (allocatedFiles[i] == file)
|
|
{
|
|
allocatedFiles[i] = allocatedFiles[--numAllocatedFiles];
|
|
break;
|
|
}
|
|
}
|
|
if (i < 0)
|
|
elog(NOTICE, "FreeFile: file was not obtained from AllocateFile");
|
|
|
|
fclose(file);
|
|
}
|
|
|
|
/*
|
|
* closeAllVfds
|
|
*
|
|
* Force all VFDs into the physically-closed state, so that the fewest
|
|
* possible number of kernel file descriptors are in use. There is no
|
|
* change in the logical state of the VFDs.
|
|
*/
|
|
void
|
|
closeAllVfds(void)
|
|
{
|
|
Index i;
|
|
|
|
if (SizeVfdCache > 0)
|
|
{
|
|
Assert(FileIsNotOpen(0)); /* Make sure ring not corrupted */
|
|
for (i = 1; i < SizeVfdCache; i++)
|
|
{
|
|
if (!FileIsNotOpen(i))
|
|
LruDelete(i);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* AtEOXact_Files
|
|
*
|
|
* This routine is called during transaction commit or abort or backend
|
|
* exit (it doesn't particularly care which). All still-open temporary-file
|
|
* VFDs are closed, which also causes the underlying files to be deleted.
|
|
* Furthermore, all "allocated" stdio files are closed.
|
|
*
|
|
* This routine is not involved in fsync'ing non-temporary files at xact
|
|
* commit; that is done by FileSync under control of the buffer manager.
|
|
* During a commit, that is done *before* control gets here. If we still
|
|
* have any needs-fsync bits set when we get here, we assume this is abort
|
|
* and clear them.
|
|
*/
|
|
void
|
|
AtEOXact_Files(void)
|
|
{
|
|
Index i;
|
|
|
|
if (SizeVfdCache > 0)
|
|
{
|
|
Assert(FileIsNotOpen(0)); /* Make sure ring not corrupted */
|
|
for (i = 1; i < SizeVfdCache; i++)
|
|
{
|
|
if ((VfdCache[i].fdstate & FD_TEMPORARY) &&
|
|
VfdCache[i].fileName != NULL)
|
|
FileClose(i);
|
|
else
|
|
VfdCache[i].fdstate &= ~FD_DIRTY;
|
|
}
|
|
}
|
|
|
|
while (numAllocatedFiles > 0)
|
|
FreeFile(allocatedFiles[0]);
|
|
|
|
/*
|
|
* Reset the tempfile name counter to 0; not really necessary, but
|
|
* helps keep the names from growing unreasonably long.
|
|
*/
|
|
tempFileCounter = 0;
|
|
}
|