* Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Id: fd.c,v 1.38 1999/03/17 22:53:06 momjian Exp $
+ * $Id: fd.c,v 1.39 1999/05/09 00:52:07 tgl Exp $
*
* NOTES:
*
*-------------------------------------------------------------------------
*/
-#include
#include
+#include
#include
#include
-#include
#include
+#include
#include
#include
#include
#include "miscadmin.h" /* for DataDir */
#include "utils/palloc.h"
#include "storage/fd.h"
+#include "utils/elog.h"
/*
- * Problem: Postgres does a system(ld...) to do dynamic loading. This
- * will open several extra files in addition to those used by
- * Postgres. We need to do this hack to guarentee that there are file
- * descriptors free for ld to use.
+ * Problem: Postgres does a system(ld...) to do dynamic loading.
+ * This will open several extra files in addition to those used by
+ * Postgres. We need to guarantee that there are file descriptors free
+ * for ld to use.
*
- * The current solution is to limit the number of files descriptors
- * that this code will allocated at one time. (it leaves
- * RESERVE_FOR_LD free).
+ * The current solution is to limit the number of file descriptors
+ * that this code will allocate at one time: it leaves RESERVE_FOR_LD free.
*
* (Even though most dynamic loaders now use dlopen(3) or the
* equivalent, the OS must still open several files to perform the
* available to postgreSQL after we've reserved the ones for LD,
* so we set that value here.
*
- * I think 10 is an apropriate value so that's what it'll be
+ * I think 10 is an appropriate value so that's what it'll be
* for now.
*/
#ifndef FD_MINFREE
#define DO_DB(A) /* A */
#endif
-#define VFD_CLOSED -1
+#define VFD_CLOSED (-1)
-#include "storage/fd.h"
-#include "utils/elog.h"
+#define FileIsValid(file) \
+ ((file) > 0 && (file) < SizeVfdCache && VfdCache[file].fileName != NULL)
#define FileIsNotOpen(file) (VfdCache[file].fd == VFD_CLOSED)
typedef struct vfd
{
- signed short fd;
- unsigned short fdstate;
+ signed short fd; /* current FD, or VFD_CLOSED if none */
+ unsigned short fdstate; /* bitflags for VFD's state */
-#define FD_DIRTY (1 << 0)
+/* these are the assigned bits in fdstate: */
+#define FD_DIRTY (1 << 0) /* written to, but not yet fsync'd */
+#define FD_TEMPORARY (1 << 1) /* should be unlinked when closed */
- File nextFree;
- File lruMoreRecently;
+ File nextFree; /* link to next free VFD, if in freelist */
+ File lruMoreRecently; /* doubly linked recency-of-use list */
File lruLessRecently;
- long seekPos;
- char *fileName;
- int fileFlags;
- int fileMode;
+ long seekPos; /* current logical file position */
+ char *fileName; /* name of file, or NULL for unused VFD */
+ /* NB: fileName is malloc'd, and must be free'd when closing the VFD */
+ int fileFlags; /* open(2) flags for opening the file */
+ int fileMode; /* mode to pass to open(2) */
} Vfd;
/*
* Virtual File Descriptor array pointer and size. This grows as
- * needed.
+ * needed. 'File' values are indexes into this array.
+ * Note that VfdCache[0] is not a usable VFD, just a list header.
*/
static Vfd *VfdCache;
static Size SizeVfdCache = 0;
/*
- * Number of file descriptors known to be open.
+ * Number of file descriptors known to be in use by VFD entries.
*/
static int nfile = 0;
/*
+ * List of stdio FILEs opened with AllocateFile.
+ *
+ * Since we don't want to encourage heavy use of AllocateFile, it seems
+ * OK to put a pretty small maximum limit on the number of simultaneously
+ * allocated files.
+ */
+#define MAX_ALLOCATED_FILES 32
+
+static int numAllocatedFiles = 0;
+static FILE * allocatedFiles[MAX_ALLOCATED_FILES];
+
+/*
+ * Number of temporary files opened during the current transaction;
+ * this is used in generation of tempfile names.
+ */
+static long tempFileCounter = 0;
+
+
+/*--------------------
+ *
* Private Routines
*
* Delete - delete a file from the Lru ring
- * LruDelete - remove a file from the Lru ring and close
+ * LruDelete - remove a file from the Lru ring and close its FD
* Insert - put a file at the front of the Lru ring
- * LruInsert - put a file at the front of the Lru ring and open
- * AssertLruRoom - make sure that there is a free fd.
+ * LruInsert - put a file at the front of the Lru ring and open it
+ * ReleaseLruFile - Release an fd by closing the last entry in the Lru ring
+ * AllocateVfd - grab a free (or new) file record (from VfdArray)
+ * FreeVfd - free a file record
*
- * the Last Recently Used ring is a doubly linked list that begins and
+ * The Least Recently Used ring is a doubly linked list that begins and
* ends on element zero. Element zero is special -- it doesn't represent
* a file and its "fd" field always == VFD_CLOSED. Element zero is just an
* anchor that shows us the beginning/end of the ring.
+ * Only VFD elements that are currently really open (have an FD assigned) are
+ * in the Lru ring. Elements that are "virtually" open can be recognized
+ * by having a non-null fileName field.
*
* example:
*
* \\less--> MostRecentlyUsedFile <---/ |
* \more---/ \--less--/
*
- * AllocateVfd - grab a free (or new) file record (from VfdArray)
- * FreeVfd - free a file record
- *
+ *--------------------
*/
static void Delete(File file);
static void LruDelete(File file);
static void Insert(File file);
static int LruInsert(File file);
-static void AssertLruRoom(void);
+static void ReleaseLruFile(void);
static File AllocateVfd(void);
static void FreeVfd(File file);
static char *filepath(char *filename);
static long pg_nofile(void);
+/*
+ * pg_fsync --- same as fsync except does nothing if -F switch was given
+ */
int
pg_fsync(int fd)
{
return disableFsync ? 0 : fsync(fd);
}
-#define fsync pg_fsync
-
+/*
+ * pg_nofile: determine number of filedescriptors that fd.c is allowed to use
+ */
static long
pg_nofile(void)
{
if (no_files == 0)
{
+ /* need do this calculation only once */
#ifndef HAVE_SYSCONF
no_files = (long) NOFILE;
#else
no_files = sysconf(_SC_OPEN_MAX);
if (no_files == -1)
{
- elog(DEBUG, "pg_nofile: Unable to get _SC_OPEN_MAX using sysconf() using (%d)", NOFILE);
+ elog(DEBUG, "pg_nofile: Unable to get _SC_OPEN_MAX using sysconf(); using %d", NOFILE);
no_files = (long) NOFILE;
}
#endif
+
+ if ((no_files - RESERVE_FOR_LD) < FD_MINFREE)
+ elog(FATAL, "pg_nofile: insufficient File Descriptors in postmaster to start backend (%ld).\n"
+ " O/S allows %ld, Postmaster reserves %d, We need %d (MIN) after that.",
+ no_files - RESERVE_FOR_LD, no_files, RESERVE_FOR_LD, FD_MINFREE);
+
+ no_files -= RESERVE_FOR_LD;
}
- if ((no_files - RESERVE_FOR_LD) < FD_MINFREE)
- elog(FATAL, "pg_nofile: insufficient File Descriptors in postmaster to start backend (%ld).\n"
- " O/S allows %ld, Postmaster reserves %d, We need %d (MIN) after that.",
- no_files - RESERVE_FOR_LD, no_files, RESERVE_FOR_LD, FD_MINFREE);
- return no_files - RESERVE_FOR_LD;
+ return no_files;
}
#if defined(FDDEBUG)
+
static void
_dump_lru()
{
static void
Delete(File file)
{
- Vfd *fileP;
+ Vfd *vfdP;
+
+ Assert(file != 0);
DO_DB(elog(DEBUG, "Delete %d (%s)",
file, VfdCache[file].fileName));
DO_DB(_dump_lru());
- Assert(file != 0);
-
- fileP = &VfdCache[file];
+ vfdP = &VfdCache[file];
- VfdCache[fileP->lruLessRecently].lruMoreRecently = VfdCache[file].lruMoreRecently;
- VfdCache[fileP->lruMoreRecently].lruLessRecently = VfdCache[file].lruLessRecently;
+ VfdCache[vfdP->lruLessRecently].lruMoreRecently = vfdP->lruMoreRecently;
+ VfdCache[vfdP->lruMoreRecently].lruLessRecently = vfdP->lruLessRecently;
DO_DB(_dump_lru());
}
static void
LruDelete(File file)
{
- Vfd *fileP;
+ Vfd *vfdP;
int returnValue;
+ Assert(file != 0);
+
DO_DB(elog(DEBUG, "LruDelete %d (%s)",
file, VfdCache[file].fileName));
- Assert(file != 0);
-
- fileP = &VfdCache[file];
+ vfdP = &VfdCache[file];
/* delete the vfd record from the LRU ring */
Delete(file);
/* save the seek position */
- fileP->seekPos = (long) lseek(fileP->fd, 0L, SEEK_CUR);
- Assert(fileP->seekPos != -1);
+ vfdP->seekPos = (long) lseek(vfdP->fd, 0L, SEEK_CUR);
+ Assert(vfdP->seekPos != -1);
/* if we have written to the file, sync it */
- if (fileP->fdstate & FD_DIRTY)
+ if (vfdP->fdstate & FD_DIRTY)
{
- returnValue = fsync(fileP->fd);
+ returnValue = pg_fsync(vfdP->fd);
Assert(returnValue != -1);
- fileP->fdstate &= ~FD_DIRTY;
+ vfdP->fdstate &= ~FD_DIRTY;
}
/* close the file */
- returnValue = close(fileP->fd);
+ returnValue = close(vfdP->fd);
Assert(returnValue != -1);
--nfile;
- fileP->fd = VFD_CLOSED;
-
+ vfdP->fd = VFD_CLOSED;
}
static void
{
Vfd *vfdP;
+ Assert(file != 0);
+
DO_DB(elog(DEBUG, "Insert %d (%s)",
file, VfdCache[file].fileName));
DO_DB(_dump_lru());
Vfd *vfdP;
int returnValue;
+ Assert(file != 0);
+
DO_DB(elog(DEBUG, "LruInsert %d (%s)",
file, VfdCache[file].fileName));
if (FileIsNotOpen(file))
{
- if (nfile >= pg_nofile())
- AssertLruRoom();
+ while (nfile+numAllocatedFiles >= pg_nofile())
+ ReleaseLruFile();
/*
- * Note, we check to see if there's a free file descriptor before
- * attempting to open a file. One general way to do this is to try
- * to open the null device which everybody should be able to open
- * all the time. If this fails, we assume this is because there's
- * no free file descriptors.
+ * The open could still fail for lack of file descriptors, eg due
+ * to overall system file table being full. So, be prepared to
+ * release another FD if necessary...
*/
tryAgain:
vfdP->fd = open(vfdP->fileName, vfdP->fileFlags, vfdP->fileMode);
if (vfdP->fd < 0 && (errno == EMFILE || errno == ENFILE))
{
errno = 0;
- AssertLruRoom();
+ ReleaseLruFile();
goto tryAgain;
}
Assert(returnValue != -1);
}
- /* init state on open */
- vfdP->fdstate = 0x0;
-
+ /* Update state as appropriate for re-open (needed?) */
+ vfdP->fdstate &= ~FD_DIRTY;
}
/*
}
static void
-AssertLruRoom()
+ReleaseLruFile()
{
- DO_DB(elog(DEBUG, "AssertLruRoom. Opened %d", nfile));
+ DO_DB(elog(DEBUG, "ReleaseLruFile. Opened %d", nfile));
if (nfile <= 0)
- elog(FATAL, "AssertLruRoom: No opened files - no one can be closed");
+ elog(FATAL, "ReleaseLruFile: No opened files - no one can be closed");
/*
* There are opened files and so there should be at least one used vfd
if (SizeVfdCache == 0)
{
-
- /* initialize */
+ /* initialize header entry first time through */
VfdCache = (Vfd *) malloc(sizeof(Vfd));
- VfdCache->nextFree = 0;
- VfdCache->lruMoreRecently = 0;
- VfdCache->lruLessRecently = 0;
+ Assert(VfdCache != NULL);
+ MemSet((char *) &(VfdCache[0]), 0, sizeof(Vfd));
VfdCache->fd = VFD_CLOSED;
- VfdCache->fdstate = 0x0;
SizeVfdCache = 1;
}
if (VfdCache[0].nextFree == 0)
{
-
/*
* The free list is empty so it is time to increase the size of
- * the array
+ * the array. We choose to double it each time this happens.
+ * However, there's not much point in starting *real* small.
*/
+ Size newCacheSize = SizeVfdCache * 2;
+
+ if (newCacheSize < 32)
+ newCacheSize = 32;
- VfdCache = (Vfd *) realloc(VfdCache, sizeof(Vfd) * SizeVfdCache * 2);
+ VfdCache = (Vfd *) realloc(VfdCache, sizeof(Vfd) * newCacheSize);
Assert(VfdCache != NULL);
/*
- * Set up the free list for the new entries
+ * Initialize the new entries and link them into the free list.
*/
- for (i = SizeVfdCache; i < 2 * SizeVfdCache; i++)
+ for (i = SizeVfdCache; i < newCacheSize; i++)
{
- MemSet((char *) &(VfdCache[i]), 0, sizeof(VfdCache[0]));
+ MemSet((char *) &(VfdCache[i]), 0, sizeof(Vfd));
VfdCache[i].nextFree = i + 1;
VfdCache[i].fd = VFD_CLOSED;
}
-
- /*
- * Element 0 is the first and last element of the free list
- */
-
+ VfdCache[newCacheSize - 1].nextFree = 0;
VfdCache[0].nextFree = SizeVfdCache;
- VfdCache[2 * SizeVfdCache - 1].nextFree = 0;
/*
* Record the new size
*/
- SizeVfdCache *= 2;
+ SizeVfdCache = newCacheSize;
}
+
file = VfdCache[0].nextFree;
VfdCache[0].nextFree = VfdCache[file].nextFree;
static void
FreeVfd(File file)
{
+ Vfd *vfdP = &VfdCache[file];
+
DO_DB(elog(DEBUG, "FreeVfd: %d (%s)",
- file, VfdCache[file].fileName));
+ file, vfdP->fileName ? vfdP->fileName : ""));
- VfdCache[file].nextFree = VfdCache[0].nextFree;
+ if (vfdP->fileName != NULL)
+ {
+ free(vfdP->fileName);
+ vfdP->fileName = NULL;
+ }
+
+ vfdP->nextFree = VfdCache[0].nextFree;
VfdCache[0].nextFree = file;
}
/* filepath()
- * Open specified file name.
- * Fill in absolute path fields if necessary.
- *
+ * Convert given pathname to absolute.
+ * (Is this actually necessary, considering that we should be cd'd
+ * into the database directory??)
*/
static char *
filepath(char *filename)
file, VfdCache[file].fileName));
/*
- * Is the file open? If not, close the least recently used, then open
- * it and stick it at the head of the used ring
+ * 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
+ 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 more it to the head of the Lru
+ * one accessed, so we need to move it to the head of the Lru
* ring.
*/
void
FileInvalidate(File file)
{
- Assert(file > 0);
+ Assert(FileIsValid(file));
if (!FileIsNotOpen(file))
LruDelete(file);
}
#endif
-/* VARARGS2 */
static File
fileNameOpenFile(FileName fileName,
int fileFlags,
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];
- if (nfile >= pg_nofile())
- AssertLruRoom();
+ while (nfile+numAllocatedFiles >= pg_nofile())
+ ReleaseLruFile();
tryAgain:
vfdP->fd = open(fileName, fileFlags, fileMode);
DO_DB(elog(DEBUG, "fileNameOpenFile: not enough descs, retry, er= %d",
errno));
errno = 0;
- AssertLruRoom();
+ ReleaseLruFile();
goto tryAgain;
}
- vfdP->fdstate = 0x0;
-
if (vfdP->fd < 0)
{
FreeVfd(file);
Insert(file);
- if (fileName == NULL)
- elog(ERROR, "fileNameOpenFile: NULL fname");
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;
}
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_temp%d.%ld", (int) getpid(), tempFileCounter++);
+
+ /* Open the file */
+#ifndef __CYGWIN32__
+ file = FileNameOpenFile(tempfilename,
+ O_RDWR | O_CREAT | O_TRUNC, 0600);
+#else
+ file = FileNameOpenFile(tempfilename,
+ O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0600);
+#endif
+
+ 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 we did any writes, sync the file before closing */
if (VfdCache[file].fdstate & FD_DIRTY)
{
- returnValue = fsync(VfdCache[file].fd);
+ returnValue = pg_fsync(VfdCache[file].fd);
Assert(returnValue != -1);
VfdCache[file].fdstate &= ~FD_DIRTY;
}
}
/*
- * Add the Vfd slot to the free list
+ * Delete the file if it was temporary
*/
- FreeVfd(file);
+ if (VfdCache[file].fdstate & FD_TEMPORARY)
+ {
+ unlink(VfdCache[file].fileName);
+ }
/*
- * Free the filename string
+ * Return the Vfd slot to the free list
*/
- free(VfdCache[file].fileName);
+ FreeVfd(file);
}
+/*
+ * close a file and forcibly delete the underlying Unix file
+ */
void
FileUnlink(File file)
{
- int returnValue;
+ Assert(FileIsValid(file));
DO_DB(elog(DEBUG, "FileUnlink: %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 = 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;
- }
- /* add the Vfd slot to the free list */
- FreeVfd(file);
+ /* force FileClose to delete it */
+ VfdCache[file].fdstate |= FD_TEMPORARY;
- /* free the filename string */
- unlink(VfdCache[file].fileName);
- free(VfdCache[file].fileName);
+ FileClose(file);
}
int
{
int returnCode;
+ Assert(FileIsValid(file));
+
DO_DB(elog(DEBUG, "FileRead: %d (%s) %d %p",
file, VfdCache[file].fileName, amount, buffer));
{
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)
- { /* changed by Boris with Mao's advice */
VfdCache[file].seekPos += returnCode;
- }
/* record the write */
VfdCache[file].fdstate |= FD_DIRTY;
long
FileSeek(File file, long offset, int whence)
{
- int returnCode;
+ Assert(FileIsValid(file));
DO_DB(elog(DEBUG, "FileSeek: %d (%s) %ld %d",
file, VfdCache[file].fileName, offset, whence));
{
case SEEK_SET:
VfdCache[file].seekPos = offset;
- return offset;
+ break;
case SEEK_CUR:
- VfdCache[file].seekPos = VfdCache[file].seekPos + offset;
- return VfdCache[file].seekPos;
+ VfdCache[file].seekPos += offset;
+ break;
case SEEK_END:
FileAccess(file);
- returnCode = VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
- return returnCode;
+ VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
+ break;
default:
elog(ERROR, "FileSeek: invalid whence: %d", whence);
break;
}
else
{
- returnCode = VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
- return returnCode;
+ VfdCache[file].seekPos = lseek(VfdCache[file].fd, offset, whence);
}
- /* NOTREACHED */
- return -1L;
+ return VfdCache[file].seekPos;
}
/*
long
FileTell(File file)
{
+ Assert(FileIsValid(file));
DO_DB(elog(DEBUG, "FileTell %d (%s)",
file, VfdCache[file].fileName));
return VfdCache[file].seekPos;
{
int returnCode;
+ Assert(FileIsValid(file));
+
DO_DB(elog(DEBUG, "FileTruncate %d (%s)",
file, VfdCache[file].fileName));
{
int returnCode;
+ Assert(FileIsValid(file));
+
/*
* If the file isn't open, then we don't need to sync it; we always
* sync files when we close them. Also, if we haven't done any writes
returnCode = 0;
else
{
- returnCode = fsync(VfdCache[file].fd);
+ returnCode = pg_fsync(VfdCache[file].fd);
VfdCache[file].fdstate &= ~FD_DIRTY;
}
}
/*
- * if we want to be sure that we have a real file descriptor available
- * (e.g., we want to know this in psort) we call AllocateFile to force
- * availability. when we are done we call FreeFile to deallocate the
- * descriptor.
+ * 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.
*
- * allocatedFiles keeps track of how many have been allocated so we
- * can give a warning if there are too few left.
+ * 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).
*/
-static int allocatedFiles = 0;
FILE *
AllocateFile(char *name, char *mode)
{
FILE *file;
- int fdleft;
- DO_DB(elog(DEBUG, "AllocateFile: Allocated %d.", allocatedFiles));
+ 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)
DO_DB(elog(DEBUG, "AllocateFile: not enough descs, retry, er= %d",
errno));
errno = 0;
- AssertLruRoom();
+ ReleaseLruFile();
goto TryAgain;
}
}
else
{
- ++allocatedFiles;
- fdleft = pg_nofile() - allocatedFiles;
- if (fdleft < 6)
- elog(NOTICE, "warning: few usable file descriptors left (%d)", fdleft);
+ allocatedFiles[numAllocatedFiles++] = file;
}
return file;
}
-/*
- * XXX What happens if FreeFile() is called without a previous
- * AllocateFile()?
- */
void
FreeFile(FILE *file)
{
- DO_DB(elog(DEBUG, "FreeFile: Allocated %d.", allocatedFiles));
+ 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");
- Assert(allocatedFiles > 0);
fclose(file);
- --allocatedFiles;
}
+/*
+ * 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()
{
- int i;
+ 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 (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.
+ */
+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);
+ }
+ }
+
+ 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;
+}
+
+
+/*
+ * Operations on BufFiles --- a very incomplete emulation of stdio
+ * atop virtual Files. Currently, we only support the buffered-I/O
+ * aspect of stdio: a read or write of the low-level File occurs only
+ * when the buffer is filled or emptied. This is an even bigger win
+ * for virtual Files than ordinary kernel files, since reducing the
+ * frequency with which a virtual File is touched reduces "thrashing"
+ * of opening/closing file descriptors.
+ *
+ * Note that BufFile structs are allocated with palloc(), and therefore
+ * will go away automatically at transaction end. If the underlying
+ * virtual File is made with OpenTemporaryFile, then all resources for
+ * the file are certain to be cleaned up even if processing is aborted
+ * by elog(ERROR).
+ */
+
+struct BufFile {
+ File file; /* the underlying virtual File */
+ bool dirty; /* does buffer need to be written? */
+ int pos; /* next read/write position in buffer */
+ int nbytes; /* total # of valid bytes in buffer */
+ char buffer[BLCKSZ];
+};
+
+
+/*
+ * Create a BufFile and attach it to an (already opened) virtual File.
+ *
+ * This is comparable to fdopen() in stdio.
+ */
+BufFile *
+BufFileCreate(File file)
+{
+ BufFile *bfile = (BufFile *) palloc(sizeof(BufFile));
+
+ bfile->file = file;
+ bfile->dirty = false;
+ bfile->pos = 0;
+ bfile->nbytes = 0;
+
+ return bfile;
+}
+
+/*
+ * Close a BufFile
+ *
+ * Like fclose(), this also implicitly FileCloses the underlying File.
+ */
+void
+BufFileClose(BufFile *file)
+{
+ /* flush any unwritten data */
+ BufFileFlush(file);
+ /* close the underlying (with delete if it's a temp file) */
+ FileClose(file->file);
+ /* release the buffer space */
+ pfree(file);
+}
+
+/* BufFileRead
+ *
+ * Like fread() except we assume 1-byte element size.
+ */
+size_t
+BufFileRead(BufFile *file, void *ptr, size_t size)
+{
+ size_t nread = 0;
+ size_t nthistime;
+
+ if (file->dirty)
+ {
+ elog(NOTICE, "BufFileRead: should have flushed after writing");
+ BufFileFlush(file);
+ }
+
+ while (size > 0)
+ {
+ if (file->pos >= file->nbytes)
+ {
+ /* Try to load more data into buffer */
+ file->pos = 0;
+ file->nbytes = FileRead(file->file, file->buffer,
+ sizeof(file->buffer));
+ if (file->nbytes < 0)
+ file->nbytes = 0;
+ if (file->nbytes <= 0)
+ break; /* no more data available */
+ }
+
+ nthistime = file->nbytes - file->pos;
+ if (nthistime > size)
+ nthistime = size;
+ Assert(nthistime > 0);
+
+ memcpy(ptr, file->buffer + file->pos, nthistime);
+
+ file->pos += nthistime;
+ ptr = (void *) ((char *) ptr + nthistime);
+ size -= nthistime;
+ nread += nthistime;
+ }
+
+ return nread;
+}
+
+/* BufFileWrite
+ *
+ * Like fwrite() except we assume 1-byte element size.
+ */
+size_t
+BufFileWrite(BufFile *file, void *ptr, size_t size)
+{
+ size_t nwritten = 0;
+ size_t nthistime;
- Assert(FileIsNotOpen(0)); /* Make sure ring not corrupted */
- for (i = 1; i < SizeVfdCache; i++)
+ while (size > 0)
{
- if (!FileIsNotOpen(i))
- LruDelete(i);
+ if (file->pos >= BLCKSZ)
+ {
+ /* Buffer full, dump it out */
+ if (file->dirty)
+ {
+ if (FileWrite(file->file, file->buffer, file->nbytes) < 0)
+ break; /* I/O error */
+ file->dirty = false;
+ }
+ file->pos = 0;
+ file->nbytes = 0;
+ }
+
+ nthistime = BLCKSZ - file->pos;
+ if (nthistime > size)
+ nthistime = size;
+ Assert(nthistime > 0);
+
+ memcpy(file->buffer + file->pos, ptr, nthistime);
+
+ file->dirty = true;
+ file->pos += nthistime;
+ if (file->nbytes < file->pos)
+ file->nbytes = file->pos;
+ ptr = (void *) ((char *) ptr + nthistime);
+ size -= nthistime;
+ nwritten += nthistime;
}
+
+ return nwritten;
+}
+
+/* BufFileFlush
+ *
+ * Like fflush()
+ */
+int
+BufFileFlush(BufFile *file)
+{
+ if (file->dirty)
+ {
+ if (FileWrite(file->file, file->buffer, file->nbytes) < 0)
+ return EOF;
+ file->dirty = false;
+ }
+
+ return 0;
+}
+
+/* BufFileSeek
+ *
+ * Like fseek(), or really more like lseek() since the return value is
+ * the new file offset (or -1 in case of error).
+ */
+long
+BufFileSeek(BufFile *file, long offset, int whence)
+{
+ if (BufFileFlush(file) < 0)
+ return -1L;
+ file->pos = 0;
+ file->nbytes = 0;
+ return FileSeek(file->file, offset, whence);
}
projects / postgresql.git / commitdiff