Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * buffile.c
4 : * Management of large buffered temporary files.
5 : *
6 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : * IDENTIFICATION
10 : * src/backend/storage/file/buffile.c
11 : *
12 : * NOTES:
13 : *
14 : * BufFiles provide a very incomplete emulation of stdio atop virtual Files
15 : * (as managed by fd.c). Currently, we only support the buffered-I/O
16 : * aspect of stdio: a read or write of the low-level File occurs only
17 : * when the buffer is filled or emptied. This is an even bigger win
18 : * for virtual Files than for ordinary kernel files, since reducing the
19 : * frequency with which a virtual File is touched reduces "thrashing"
20 : * of opening/closing file descriptors.
21 : *
22 : * Note that BufFile structs are allocated with palloc(), and therefore
23 : * will go away automatically at query/transaction end. Since the underlying
24 : * virtual Files are made with OpenTemporaryFile, all resources for
25 : * the file are certain to be cleaned up even if processing is aborted
26 : * by ereport(ERROR). The data structures required are made in the
27 : * palloc context that was current when the BufFile was created, and
28 : * any external resources such as temp files are owned by the ResourceOwner
29 : * that was current at that time.
30 : *
31 : * BufFile also supports temporary files that exceed the OS file size limit
32 : * (by opening multiple fd.c temporary files). This is an essential feature
33 : * for sorts and hashjoins on large amounts of data.
34 : *
35 : * BufFile supports temporary files that can be shared with other backends, as
36 : * infrastructure for parallel execution. Such files need to be created as a
37 : * member of a SharedFileSet that all participants are attached to.
38 : *
39 : * BufFile also supports temporary files that can be used by the single backend
40 : * when the corresponding files need to be survived across the transaction and
41 : * need to be opened and closed multiple times. Such files need to be created
42 : * as a member of a FileSet.
43 : *-------------------------------------------------------------------------
44 : */
45 :
46 : #include "postgres.h"
47 :
48 : #include "commands/tablespace.h"
49 : #include "executor/instrument.h"
50 : #include "miscadmin.h"
51 : #include "pgstat.h"
52 : #include "storage/buffile.h"
53 : #include "storage/bufmgr.h"
54 : #include "storage/fd.h"
55 : #include "utils/resowner.h"
56 :
57 : /*
58 : * We break BufFiles into gigabyte-sized segments, regardless of RELSEG_SIZE.
59 : * The reason is that we'd like large BufFiles to be spread across multiple
60 : * tablespaces when available.
61 : */
62 : #define MAX_PHYSICAL_FILESIZE 0x40000000
63 : #define BUFFILE_SEG_SIZE (MAX_PHYSICAL_FILESIZE / BLCKSZ)
64 :
65 : /*
66 : * This data structure represents a buffered file that consists of one or
67 : * more physical files (each accessed through a virtual file descriptor
68 : * managed by fd.c).
69 : */
70 : struct BufFile
71 : {
72 : int numFiles; /* number of physical files in set */
73 : /* all files except the last have length exactly MAX_PHYSICAL_FILESIZE */
74 : File *files; /* palloc'd array with numFiles entries */
75 :
76 : bool isInterXact; /* keep open over transactions? */
77 : bool dirty; /* does buffer need to be written? */
78 : bool readOnly; /* has the file been set to read only? */
79 :
80 : FileSet *fileset; /* space for fileset based segment files */
81 : const char *name; /* name of fileset based BufFile */
82 :
83 : /*
84 : * resowner is the ResourceOwner to use for underlying temp files. (We
85 : * don't need to remember the memory context we're using explicitly,
86 : * because after creation we only repalloc our arrays larger.)
87 : */
88 : ResourceOwner resowner;
89 :
90 : /*
91 : * "current pos" is position of start of buffer within the logical file.
92 : * Position as seen by user of BufFile is (curFile, curOffset + pos).
93 : */
94 : int curFile; /* file index (0..n) part of current pos */
95 : pgoff_t curOffset; /* offset part of current pos */
96 : int64 pos; /* next read/write position in buffer */
97 : int64 nbytes; /* total # of valid bytes in buffer */
98 :
99 : /*
100 : * XXX Should ideally use PGIOAlignedBlock, but might need a way to avoid
101 : * wasting per-file alignment padding when some users create many files.
102 : */
103 : PGAlignedBlock buffer;
104 : };
105 :
106 : static BufFile *makeBufFileCommon(int nfiles);
107 : static BufFile *makeBufFile(File firstfile);
108 : static void extendBufFile(BufFile *file);
109 : static void BufFileLoadBuffer(BufFile *file);
110 : static void BufFileDumpBuffer(BufFile *file);
111 : static void BufFileFlush(BufFile *file);
112 : static File MakeNewFileSetSegment(BufFile *buffile, int segment);
113 :
114 : /*
115 : * Create BufFile and perform the common initialization.
116 : */
117 : static BufFile *
118 5065 : makeBufFileCommon(int nfiles)
119 : {
120 5065 : BufFile *file = palloc_object(BufFile);
121 :
122 5065 : file->numFiles = nfiles;
123 5065 : file->isInterXact = false;
124 5065 : file->dirty = false;
125 5065 : file->resowner = CurrentResourceOwner;
126 5065 : file->curFile = 0;
127 5065 : file->curOffset = 0;
128 5065 : file->pos = 0;
129 5065 : file->nbytes = 0;
130 :
131 5065 : return file;
132 : }
133 :
134 : /*
135 : * Create a BufFile given the first underlying physical file.
136 : * NOTE: caller must set isInterXact if appropriate.
137 : */
138 : static BufFile *
139 1563 : makeBufFile(File firstfile)
140 : {
141 1563 : BufFile *file = makeBufFileCommon(1);
142 :
143 1563 : file->files = palloc_object(File);
144 1563 : file->files[0] = firstfile;
145 1563 : file->readOnly = false;
146 1563 : file->fileset = NULL;
147 1563 : file->name = NULL;
148 :
149 1563 : return file;
150 : }
151 :
152 : /*
153 : * Add another component temp file.
154 : */
155 : static void
156 0 : extendBufFile(BufFile *file)
157 : {
158 : File pfile;
159 : ResourceOwner oldowner;
160 :
161 : /* Be sure to associate the file with the BufFile's resource owner */
162 0 : oldowner = CurrentResourceOwner;
163 0 : CurrentResourceOwner = file->resowner;
164 :
165 0 : if (file->fileset == NULL)
166 0 : pfile = OpenTemporaryFile(file->isInterXact);
167 : else
168 0 : pfile = MakeNewFileSetSegment(file, file->numFiles);
169 :
170 : Assert(pfile >= 0);
171 :
172 0 : CurrentResourceOwner = oldowner;
173 :
174 0 : file->files = (File *) repalloc(file->files,
175 0 : (file->numFiles + 1) * sizeof(File));
176 0 : file->files[file->numFiles] = pfile;
177 0 : file->numFiles++;
178 0 : }
179 :
180 : /*
181 : * Create a BufFile for a new temporary file (which will expand to become
182 : * multiple temporary files if more than MAX_PHYSICAL_FILESIZE bytes are
183 : * written to it).
184 : *
185 : * If interXact is true, the temp file will not be automatically deleted
186 : * at end of transaction.
187 : *
188 : * Note: if interXact is true, the caller had better be calling us in a
189 : * memory context, and with a resource owner, that will survive across
190 : * transaction boundaries.
191 : */
192 : BufFile *
193 1563 : BufFileCreateTemp(bool interXact)
194 : {
195 : BufFile *file;
196 : File pfile;
197 :
198 : /*
199 : * Ensure that temp tablespaces are set up for OpenTemporaryFile to use.
200 : * Possibly the caller will have done this already, but it seems useful to
201 : * double-check here. Failure to do this at all would result in the temp
202 : * files always getting placed in the default tablespace, which is a
203 : * pretty hard-to-detect bug. Callers may prefer to do it earlier if they
204 : * want to be sure that any required catalog access is done in some other
205 : * resource context.
206 : */
207 1563 : PrepareTempTablespaces();
208 :
209 1563 : pfile = OpenTemporaryFile(interXact);
210 : Assert(pfile >= 0);
211 :
212 1563 : file = makeBufFile(pfile);
213 1563 : file->isInterXact = interXact;
214 :
215 1563 : return file;
216 : }
217 :
218 : /*
219 : * Build the name for a given segment of a given BufFile.
220 : */
221 : static void
222 7668 : FileSetSegmentName(char *name, const char *buffile_name, int segment)
223 : {
224 7668 : snprintf(name, MAXPGPATH, "%s.%d", buffile_name, segment);
225 7668 : }
226 :
227 : /*
228 : * Create a new segment file backing a fileset based BufFile.
229 : */
230 : static File
231 1524 : MakeNewFileSetSegment(BufFile *buffile, int segment)
232 : {
233 : char name[MAXPGPATH];
234 : File file;
235 :
236 : /*
237 : * It is possible that there are files left over from before a crash
238 : * restart with the same name. In order for BufFileOpenFileSet() not to
239 : * get confused about how many segments there are, we'll unlink the next
240 : * segment number if it already exists.
241 : */
242 1524 : FileSetSegmentName(name, buffile->name, segment + 1);
243 1524 : FileSetDelete(buffile->fileset, name, true);
244 :
245 : /* Create the new segment. */
246 1524 : FileSetSegmentName(name, buffile->name, segment);
247 1524 : file = FileSetCreate(buffile->fileset, name);
248 :
249 : /* FileSetCreate would've errored out */
250 : Assert(file > 0);
251 :
252 1524 : return file;
253 : }
254 :
255 : /*
256 : * Create a BufFile that can be discovered and opened read-only by other
257 : * backends that are attached to the same SharedFileSet using the same name.
258 : *
259 : * The naming scheme for fileset based BufFiles is left up to the calling code.
260 : * The name will appear as part of one or more filenames on disk, and might
261 : * provide clues to administrators about which subsystem is generating
262 : * temporary file data. Since each SharedFileSet object is backed by one or
263 : * more uniquely named temporary directory, names don't conflict with
264 : * unrelated SharedFileSet objects.
265 : */
266 : BufFile *
267 1524 : BufFileCreateFileSet(FileSet *fileset, const char *name)
268 : {
269 : BufFile *file;
270 :
271 1524 : file = makeBufFileCommon(1);
272 1524 : file->fileset = fileset;
273 1524 : file->name = pstrdup(name);
274 1524 : file->files = palloc_object(File);
275 1524 : file->files[0] = MakeNewFileSetSegment(file, 0);
276 1524 : file->readOnly = false;
277 :
278 1524 : return file;
279 : }
280 :
281 : /*
282 : * Open a file that was previously created in another backend (or this one)
283 : * with BufFileCreateFileSet in the same FileSet using the same name.
284 : * The backend that created the file must have called BufFileClose() or
285 : * BufFileExportFileSet() to make sure that it is ready to be opened by other
286 : * backends and render it read-only. If missing_ok is true, which indicates
287 : * that missing files can be safely ignored, then return NULL if the BufFile
288 : * with the given name is not found, otherwise, throw an error.
289 : */
290 : BufFile *
291 2251 : BufFileOpenFileSet(FileSet *fileset, const char *name, int mode,
292 : bool missing_ok)
293 : {
294 : BufFile *file;
295 : char segment_name[MAXPGPATH];
296 2251 : Size capacity = 16;
297 : File *files;
298 2251 : int nfiles = 0;
299 :
300 2251 : files = palloc_array(File, capacity);
301 :
302 : /*
303 : * We don't know how many segments there are, so we'll probe the
304 : * filesystem to find out.
305 : */
306 : for (;;)
307 : {
308 : /* See if we need to expand our file segment array. */
309 4229 : if (nfiles + 1 > capacity)
310 : {
311 0 : capacity *= 2;
312 0 : files = repalloc_array(files, File, capacity);
313 : }
314 : /* Try to load a segment. */
315 4229 : FileSetSegmentName(segment_name, name, nfiles);
316 4229 : files[nfiles] = FileSetOpen(fileset, segment_name, mode);
317 4229 : if (files[nfiles] <= 0)
318 2251 : break;
319 1978 : ++nfiles;
320 :
321 1978 : CHECK_FOR_INTERRUPTS();
322 : }
323 :
324 : /*
325 : * If we didn't find any files at all, then no BufFile exists with this
326 : * name.
327 : */
328 2251 : if (nfiles == 0)
329 : {
330 : /* free the memory */
331 273 : pfree(files);
332 :
333 273 : if (missing_ok)
334 273 : return NULL;
335 :
336 0 : ereport(ERROR,
337 : (errcode_for_file_access(),
338 : errmsg("could not open temporary file \"%s\" from BufFile \"%s\": %m",
339 : segment_name, name)));
340 : }
341 :
342 1978 : file = makeBufFileCommon(nfiles);
343 1978 : file->files = files;
344 1978 : file->readOnly = (mode == O_RDONLY);
345 1978 : file->fileset = fileset;
346 1978 : file->name = pstrdup(name);
347 :
348 1978 : return file;
349 : }
350 :
351 : /*
352 : * Delete a BufFile that was created by BufFileCreateFileSet in the given
353 : * FileSet using the given name.
354 : *
355 : * It is not necessary to delete files explicitly with this function. It is
356 : * provided only as a way to delete files proactively, rather than waiting for
357 : * the FileSet to be cleaned up.
358 : *
359 : * Only one backend should attempt to delete a given name, and should know
360 : * that it exists and has been exported or closed otherwise missing_ok should
361 : * be passed true.
362 : */
363 : void
364 352 : BufFileDeleteFileSet(FileSet *fileset, const char *name, bool missing_ok)
365 : {
366 : char segment_name[MAXPGPATH];
367 352 : int segment = 0;
368 352 : bool found = false;
369 :
370 : /*
371 : * We don't know how many segments the file has. We'll keep deleting
372 : * until we run out. If we don't manage to find even an initial segment,
373 : * raise an error.
374 : */
375 : for (;;)
376 : {
377 391 : FileSetSegmentName(segment_name, name, segment);
378 391 : if (!FileSetDelete(fileset, segment_name, true))
379 352 : break;
380 39 : found = true;
381 39 : ++segment;
382 :
383 39 : CHECK_FOR_INTERRUPTS();
384 : }
385 :
386 352 : if (!found && !missing_ok)
387 0 : elog(ERROR, "could not delete unknown BufFile \"%s\"", name);
388 352 : }
389 :
390 : /*
391 : * BufFileExportFileSet --- flush and make read-only, in preparation for sharing.
392 : */
393 : void
394 282 : BufFileExportFileSet(BufFile *file)
395 : {
396 : /* Must be a file belonging to a FileSet. */
397 : Assert(file->fileset != NULL);
398 :
399 : /* It's probably a bug if someone calls this twice. */
400 : Assert(!file->readOnly);
401 :
402 282 : BufFileFlush(file);
403 282 : file->readOnly = true;
404 282 : }
405 :
406 : /*
407 : * Close a BufFile
408 : *
409 : * Like fclose(), this also implicitly FileCloses the underlying File.
410 : */
411 : void
412 4942 : BufFileClose(BufFile *file)
413 : {
414 : int i;
415 :
416 : /* flush any unwritten data */
417 4942 : BufFileFlush(file);
418 : /* close and delete the underlying file(s) */
419 9999 : for (i = 0; i < file->numFiles; i++)
420 5057 : FileClose(file->files[i]);
421 : /* release the buffer space */
422 4942 : pfree(file->files);
423 4942 : pfree(file);
424 4942 : }
425 :
426 : /*
427 : * BufFileLoadBuffer
428 : *
429 : * Load some data into buffer, if possible, starting from curOffset.
430 : * At call, must have dirty = false, pos and nbytes = 0.
431 : * On exit, nbytes is number of bytes loaded.
432 : */
433 : static void
434 50259 : BufFileLoadBuffer(BufFile *file)
435 : {
436 : File thisfile;
437 : instr_time io_start;
438 : instr_time io_time;
439 :
440 : /*
441 : * Advance to next component file if necessary and possible.
442 : */
443 50259 : if (file->curOffset >= MAX_PHYSICAL_FILESIZE &&
444 0 : file->curFile + 1 < file->numFiles)
445 : {
446 0 : file->curFile++;
447 0 : file->curOffset = 0;
448 : }
449 :
450 50259 : thisfile = file->files[file->curFile];
451 :
452 50259 : if (track_io_timing)
453 0 : INSTR_TIME_SET_CURRENT(io_start);
454 : else
455 50259 : INSTR_TIME_SET_ZERO(io_start);
456 :
457 : /*
458 : * Read whatever we can get, up to a full bufferload.
459 : */
460 100518 : file->nbytes = FileRead(thisfile,
461 50259 : file->buffer.data,
462 : sizeof(file->buffer.data),
463 : file->curOffset,
464 : WAIT_EVENT_BUFFILE_READ);
465 50259 : if (file->nbytes < 0)
466 : {
467 0 : file->nbytes = 0;
468 0 : ereport(ERROR,
469 : (errcode_for_file_access(),
470 : errmsg("could not read file \"%s\": %m",
471 : FilePathName(thisfile))));
472 : }
473 :
474 50259 : if (track_io_timing)
475 : {
476 0 : INSTR_TIME_SET_CURRENT(io_time);
477 0 : INSTR_TIME_ACCUM_DIFF(pgBufferUsage.temp_blk_read_time, io_time, io_start);
478 : }
479 :
480 : /* we choose not to advance curOffset here */
481 :
482 50259 : if (file->nbytes > 0)
483 48952 : pgBufferUsage.temp_blks_read++;
484 50259 : }
485 :
486 : /*
487 : * BufFileDumpBuffer
488 : *
489 : * Dump buffer contents starting at curOffset.
490 : * At call, should have dirty = true, nbytes > 0.
491 : * On exit, dirty is cleared if successful write, and curOffset is advanced.
492 : */
493 : static void
494 56772 : BufFileDumpBuffer(BufFile *file)
495 : {
496 56772 : int64 wpos = 0;
497 : int64 bytestowrite;
498 : File thisfile;
499 :
500 : /*
501 : * Unlike BufFileLoadBuffer, we must dump the whole buffer even if it
502 : * crosses a component-file boundary; so we need a loop.
503 : */
504 113544 : while (wpos < file->nbytes)
505 : {
506 : int64 availbytes;
507 : instr_time io_start;
508 : instr_time io_time;
509 :
510 : /*
511 : * Advance to next component file if necessary and possible.
512 : */
513 56772 : if (file->curOffset >= MAX_PHYSICAL_FILESIZE)
514 : {
515 0 : while (file->curFile + 1 >= file->numFiles)
516 0 : extendBufFile(file);
517 0 : file->curFile++;
518 0 : file->curOffset = 0;
519 : }
520 :
521 : /*
522 : * Determine how much we need to write into this file.
523 : */
524 56772 : bytestowrite = file->nbytes - wpos;
525 56772 : availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset;
526 :
527 56772 : if (bytestowrite > availbytes)
528 0 : bytestowrite = availbytes;
529 :
530 56772 : thisfile = file->files[file->curFile];
531 :
532 56772 : if (track_io_timing)
533 0 : INSTR_TIME_SET_CURRENT(io_start);
534 : else
535 56772 : INSTR_TIME_SET_ZERO(io_start);
536 :
537 56772 : bytestowrite = FileWrite(thisfile,
538 56772 : file->buffer.data + wpos,
539 : bytestowrite,
540 : file->curOffset,
541 : WAIT_EVENT_BUFFILE_WRITE);
542 56772 : if (bytestowrite <= 0)
543 0 : ereport(ERROR,
544 : (errcode_for_file_access(),
545 : errmsg("could not write to file \"%s\": %m",
546 : FilePathName(thisfile))));
547 :
548 56772 : if (track_io_timing)
549 : {
550 0 : INSTR_TIME_SET_CURRENT(io_time);
551 0 : INSTR_TIME_ACCUM_DIFF(pgBufferUsage.temp_blk_write_time, io_time, io_start);
552 : }
553 :
554 56772 : file->curOffset += bytestowrite;
555 56772 : wpos += bytestowrite;
556 :
557 56772 : pgBufferUsage.temp_blks_written++;
558 : }
559 56772 : file->dirty = false;
560 :
561 : /*
562 : * At this point, curOffset has been advanced to the end of the buffer,
563 : * ie, its original value + nbytes. We need to make it point to the
564 : * logical file position, ie, original value + pos, in case that is less
565 : * (as could happen due to a small backwards seek in a dirty buffer!)
566 : */
567 56772 : file->curOffset -= (file->nbytes - file->pos);
568 56772 : if (file->curOffset < 0) /* handle possible segment crossing */
569 : {
570 0 : file->curFile--;
571 : Assert(file->curFile >= 0);
572 0 : file->curOffset += MAX_PHYSICAL_FILESIZE;
573 : }
574 :
575 : /*
576 : * Now we can set the buffer empty without changing the logical position
577 : */
578 56772 : file->pos = 0;
579 56772 : file->nbytes = 0;
580 56772 : }
581 :
582 : /*
583 : * BufFileRead variants
584 : *
585 : * Like fread() except we assume 1-byte element size and report I/O errors via
586 : * ereport().
587 : *
588 : * If 'exact' is true, then an error is also raised if the number of bytes
589 : * read is not exactly 'size' (no short reads). If 'exact' and 'eofOK' are
590 : * true, then reading zero bytes is ok.
591 : */
592 : static size_t
593 12657397 : BufFileReadCommon(BufFile *file, void *ptr, size_t size, bool exact, bool eofOK)
594 : {
595 12657397 : size_t start_size = size;
596 12657397 : size_t nread = 0;
597 : size_t nthistime;
598 :
599 12657397 : BufFileFlush(file);
600 :
601 25326890 : while (size > 0)
602 : {
603 12670800 : if (file->pos >= file->nbytes)
604 : {
605 : /* Try to load more data into buffer. */
606 50259 : file->curOffset += file->pos;
607 50259 : file->pos = 0;
608 50259 : file->nbytes = 0;
609 50259 : BufFileLoadBuffer(file);
610 50259 : if (file->nbytes <= 0)
611 1307 : break; /* no more data available */
612 : }
613 :
614 12669493 : nthistime = file->nbytes - file->pos;
615 12669493 : if (nthistime > size)
616 12622121 : nthistime = size;
617 : Assert(nthistime > 0);
618 :
619 12669493 : memcpy(ptr, file->buffer.data + file->pos, nthistime);
620 :
621 12669493 : file->pos += nthistime;
622 12669493 : ptr = (char *) ptr + nthistime;
623 12669493 : size -= nthistime;
624 12669493 : nread += nthistime;
625 : }
626 :
627 12657397 : if (exact &&
628 1307 : (nread != start_size && !(nread == 0 && eofOK)))
629 0 : ereport(ERROR,
630 : errcode_for_file_access(),
631 : file->name ?
632 : errmsg("could not read from file set \"%s\": read only %zu of %zu bytes",
633 : file->name, nread, start_size) :
634 : errmsg("could not read from temporary file: read only %zu of %zu bytes",
635 : nread, start_size));
636 :
637 12657397 : return nread;
638 : }
639 :
640 : /*
641 : * Legacy interface where the caller needs to check for end of file or short
642 : * reads.
643 : */
644 : size_t
645 0 : BufFileRead(BufFile *file, void *ptr, size_t size)
646 : {
647 0 : return BufFileReadCommon(file, ptr, size, false, false);
648 : }
649 :
650 : /*
651 : * Require read of exactly the specified size.
652 : */
653 : void
654 8171176 : BufFileReadExact(BufFile *file, void *ptr, size_t size)
655 : {
656 8171176 : BufFileReadCommon(file, ptr, size, true, false);
657 8171176 : }
658 :
659 : /*
660 : * Require read of exactly the specified size, but optionally allow end of
661 : * file (in which case 0 is returned).
662 : */
663 : size_t
664 4486221 : BufFileReadMaybeEOF(BufFile *file, void *ptr, size_t size, bool eofOK)
665 : {
666 4486221 : return BufFileReadCommon(file, ptr, size, true, eofOK);
667 : }
668 :
669 : /*
670 : * BufFileWrite
671 : *
672 : * Like fwrite() except we assume 1-byte element size and report errors via
673 : * ereport().
674 : */
675 : void
676 11413225 : BufFileWrite(BufFile *file, const void *ptr, size_t size)
677 : {
678 : size_t nthistime;
679 :
680 : Assert(!file->readOnly);
681 :
682 22848359 : while (size > 0)
683 : {
684 11435134 : if (file->pos >= BLCKSZ)
685 : {
686 : /* Buffer full, dump it out */
687 36339 : if (file->dirty)
688 36102 : BufFileDumpBuffer(file);
689 : else
690 : {
691 : /* Hmm, went directly from reading to writing? */
692 237 : file->curOffset += file->pos;
693 237 : file->pos = 0;
694 237 : file->nbytes = 0;
695 : }
696 : }
697 :
698 11435134 : nthistime = BLCKSZ - file->pos;
699 11435134 : if (nthistime > size)
700 11380257 : nthistime = size;
701 : Assert(nthistime > 0);
702 :
703 11435134 : memcpy(file->buffer.data + file->pos, ptr, nthistime);
704 :
705 11435134 : file->dirty = true;
706 11435134 : file->pos += nthistime;
707 11435134 : if (file->nbytes < file->pos)
708 11433202 : file->nbytes = file->pos;
709 11435134 : ptr = (const char *) ptr + nthistime;
710 11435134 : size -= nthistime;
711 : }
712 11413225 : }
713 :
714 : /*
715 : * BufFileFlush
716 : *
717 : * Like fflush(), except that I/O errors are reported with ereport().
718 : */
719 : static void
720 12689405 : BufFileFlush(BufFile *file)
721 : {
722 12689405 : if (file->dirty)
723 20670 : BufFileDumpBuffer(file);
724 :
725 : Assert(!file->dirty);
726 12689405 : }
727 :
728 : /*
729 : * BufFileSeek
730 : *
731 : * Like fseek(), except that target position needs two values in order to
732 : * work when logical filesize exceeds maximum value representable by pgoff_t.
733 : * We do not support relative seeks across more than that, however.
734 : * I/O errors are reported by ereport().
735 : *
736 : * Result is 0 if OK, EOF if not. Logical position is not moved if an
737 : * impossible seek is attempted.
738 : */
739 : int
740 56017 : BufFileSeek(BufFile *file, int fileno, pgoff_t offset, int whence)
741 : {
742 : int newFile;
743 : pgoff_t newOffset;
744 :
745 56017 : switch (whence)
746 : {
747 55682 : case SEEK_SET:
748 55682 : if (fileno < 0)
749 0 : return EOF;
750 55682 : newFile = fileno;
751 55682 : newOffset = offset;
752 55682 : break;
753 0 : case SEEK_CUR:
754 :
755 : /*
756 : * Relative seek considers only the signed offset, ignoring
757 : * fileno.
758 : */
759 0 : newFile = file->curFile;
760 0 : newOffset = (file->curOffset + file->pos) + offset;
761 0 : break;
762 335 : case SEEK_END:
763 :
764 : /*
765 : * The file size of the last file gives us the end offset of that
766 : * file.
767 : */
768 335 : newFile = file->numFiles - 1;
769 335 : newOffset = FileSize(file->files[file->numFiles - 1]);
770 335 : if (newOffset < 0)
771 0 : ereport(ERROR,
772 : (errcode_for_file_access(),
773 : errmsg("could not determine size of temporary file \"%s\" from BufFile \"%s\": %m",
774 : FilePathName(file->files[file->numFiles - 1]),
775 : file->name)));
776 335 : break;
777 0 : default:
778 0 : elog(ERROR, "invalid whence: %d", whence);
779 : return EOF;
780 : }
781 56017 : while (newOffset < 0)
782 : {
783 0 : if (--newFile < 0)
784 0 : return EOF;
785 0 : newOffset += MAX_PHYSICAL_FILESIZE;
786 : }
787 56017 : if (newFile == file->curFile &&
788 55902 : newOffset >= file->curOffset &&
789 41308 : newOffset <= file->curOffset + file->nbytes)
790 : {
791 : /*
792 : * Seek is to a point within existing buffer; we can just adjust
793 : * pos-within-buffer, without flushing buffer. Note this is OK
794 : * whether reading or writing, but buffer remains dirty if we were
795 : * writing.
796 : */
797 29233 : file->pos = (int64) (newOffset - file->curOffset);
798 29233 : return 0;
799 : }
800 : /* Otherwise, must reposition buffer, so flush any dirty data */
801 26784 : BufFileFlush(file);
802 :
803 : /*
804 : * At this point and no sooner, check for seek past last segment. The
805 : * above flush could have created a new segment, so checking sooner would
806 : * not work (at least not with this code).
807 : */
808 :
809 : /* convert seek to "start of next seg" to "end of last seg" */
810 26784 : if (newFile == file->numFiles && newOffset == 0)
811 : {
812 0 : newFile--;
813 0 : newOffset = MAX_PHYSICAL_FILESIZE;
814 : }
815 26784 : while (newOffset > MAX_PHYSICAL_FILESIZE)
816 : {
817 0 : if (++newFile >= file->numFiles)
818 0 : return EOF;
819 0 : newOffset -= MAX_PHYSICAL_FILESIZE;
820 : }
821 26784 : if (newFile >= file->numFiles)
822 0 : return EOF;
823 : /* Seek is OK! */
824 26784 : file->curFile = newFile;
825 26784 : file->curOffset = newOffset;
826 26784 : file->pos = 0;
827 26784 : file->nbytes = 0;
828 26784 : return 0;
829 : }
830 :
831 : void
832 88620 : BufFileTell(BufFile *file, int *fileno, pgoff_t *offset)
833 : {
834 88620 : *fileno = file->curFile;
835 88620 : *offset = file->curOffset + file->pos;
836 88620 : }
837 :
838 : /*
839 : * BufFileSeekBlock --- block-oriented seek
840 : *
841 : * Performs absolute seek to the start of the n'th BLCKSZ-sized block of
842 : * the file. Note that users of this interface will fail if their files
843 : * exceed BLCKSZ * PG_INT64_MAX bytes, but that is quite a lot; we don't
844 : * work with tables bigger than that, either...
845 : *
846 : * Result is 0 if OK, EOF if not. Logical position is not moved if an
847 : * impossible seek is attempted.
848 : */
849 : int
850 54211 : BufFileSeekBlock(BufFile *file, int64 blknum)
851 : {
852 108422 : return BufFileSeek(file,
853 54211 : (int) (blknum / BUFFILE_SEG_SIZE),
854 54211 : (pgoff_t) (blknum % BUFFILE_SEG_SIZE) * BLCKSZ,
855 : SEEK_SET);
856 : }
857 :
858 : /*
859 : * Returns the amount of data in the given BufFile, in bytes.
860 : *
861 : * Returned value includes the size of any holes left behind by BufFileAppend.
862 : * ereport()s on failure.
863 : */
864 : int64
865 218 : BufFileSize(BufFile *file)
866 : {
867 : int64 lastFileSize;
868 :
869 : /* Get the size of the last physical file. */
870 218 : lastFileSize = FileSize(file->files[file->numFiles - 1]);
871 218 : if (lastFileSize < 0)
872 0 : ereport(ERROR,
873 : (errcode_for_file_access(),
874 : errmsg("could not determine size of temporary file \"%s\" from BufFile \"%s\": %m",
875 : FilePathName(file->files[file->numFiles - 1]),
876 : file->name)));
877 :
878 218 : return ((file->numFiles - 1) * (int64) MAX_PHYSICAL_FILESIZE) +
879 : lastFileSize;
880 : }
881 :
882 : /*
883 : * Append the contents of the source file to the end of the target file.
884 : *
885 : * Note that operation subsumes ownership of underlying resources from
886 : * "source". Caller should never call BufFileClose against source having
887 : * called here first. Resource owners for source and target must match,
888 : * too.
889 : *
890 : * This operation works by manipulating lists of segment files, so the
891 : * file content is always appended at a MAX_PHYSICAL_FILESIZE-aligned
892 : * boundary, typically creating empty holes before the boundary. These
893 : * areas do not contain any interesting data, and cannot be read from by
894 : * caller.
895 : *
896 : * Returns the block number within target where the contents of source
897 : * begins. Caller should apply this as an offset when working off block
898 : * positions that are in terms of the original BufFile space.
899 : */
900 : int64
901 115 : BufFileAppend(BufFile *target, BufFile *source)
902 : {
903 115 : int64 startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;
904 115 : int newNumFiles = target->numFiles + source->numFiles;
905 : int i;
906 :
907 : Assert(source->readOnly);
908 : Assert(!source->dirty);
909 :
910 115 : if (target->resowner != source->resowner)
911 0 : elog(ERROR, "could not append BufFile with non-matching resource owner");
912 :
913 115 : target->files = (File *)
914 115 : repalloc(target->files, sizeof(File) * newNumFiles);
915 230 : for (i = target->numFiles; i < newNumFiles; i++)
916 115 : target->files[i] = source->files[i - target->numFiles];
917 115 : target->numFiles = newNumFiles;
918 :
919 115 : return startBlock;
920 : }
921 :
922 : /*
923 : * Truncate a BufFile created by BufFileCreateFileSet up to the given fileno
924 : * and the offset.
925 : */
926 : void
927 9 : BufFileTruncateFileSet(BufFile *file, int fileno, pgoff_t offset)
928 : {
929 9 : int numFiles = file->numFiles;
930 9 : int newFile = fileno;
931 9 : pgoff_t newOffset = file->curOffset;
932 : char segment_name[MAXPGPATH];
933 : int i;
934 :
935 : /*
936 : * Loop over all the files up to the given fileno and remove the files
937 : * that are greater than the fileno and truncate the given file up to the
938 : * offset. Note that we also remove the given fileno if the offset is 0
939 : * provided it is not the first file in which we truncate it.
940 : */
941 18 : for (i = file->numFiles - 1; i >= fileno; i--)
942 : {
943 9 : if ((i != fileno || offset == 0) && i != 0)
944 : {
945 0 : FileSetSegmentName(segment_name, file->name, i);
946 0 : FileClose(file->files[i]);
947 0 : if (!FileSetDelete(file->fileset, segment_name, true))
948 0 : ereport(ERROR,
949 : (errcode_for_file_access(),
950 : errmsg("could not delete fileset \"%s\": %m",
951 : segment_name)));
952 0 : numFiles--;
953 0 : newOffset = MAX_PHYSICAL_FILESIZE;
954 :
955 : /*
956 : * This is required to indicate that we have deleted the given
957 : * fileno.
958 : */
959 0 : if (i == fileno)
960 0 : newFile--;
961 : }
962 : else
963 : {
964 9 : if (FileTruncate(file->files[i], offset,
965 : WAIT_EVENT_BUFFILE_TRUNCATE) < 0)
966 0 : ereport(ERROR,
967 : (errcode_for_file_access(),
968 : errmsg("could not truncate file \"%s\": %m",
969 : FilePathName(file->files[i]))));
970 9 : newOffset = offset;
971 : }
972 : }
973 :
974 9 : file->numFiles = numFiles;
975 :
976 : /*
977 : * If the truncate point is within existing buffer then we can just adjust
978 : * pos within buffer.
979 : */
980 9 : if (newFile == file->curFile &&
981 9 : newOffset >= file->curOffset &&
982 9 : newOffset <= file->curOffset + file->nbytes)
983 : {
984 : /* No need to reset the current pos if the new pos is greater. */
985 0 : if (newOffset <= file->curOffset + file->pos)
986 0 : file->pos = (int64) newOffset - file->curOffset;
987 :
988 : /* Adjust the nbytes for the current buffer. */
989 0 : file->nbytes = (int64) newOffset - file->curOffset;
990 : }
991 9 : else if (newFile == file->curFile &&
992 9 : newOffset < file->curOffset)
993 : {
994 : /*
995 : * The truncate point is within the existing file but prior to the
996 : * current position, so we can forget the current buffer and reset the
997 : * current position.
998 : */
999 0 : file->curOffset = newOffset;
1000 0 : file->pos = 0;
1001 0 : file->nbytes = 0;
1002 : }
1003 9 : else if (newFile < file->curFile)
1004 : {
1005 : /*
1006 : * The truncate point is prior to the current file, so need to reset
1007 : * the current position accordingly.
1008 : */
1009 0 : file->curFile = newFile;
1010 0 : file->curOffset = newOffset;
1011 0 : file->pos = 0;
1012 0 : file->nbytes = 0;
1013 : }
1014 : /* Nothing to do, if the truncate point is beyond current file. */
1015 9 : }
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