Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * buffile.c
4 : * Management of large buffered temporary files.
5 : *
6 : * Portions Copyright (c) 1996-2024, 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 : off_t curOffset; /* offset part of current pos */
96 : int pos; /* next read/write position in buffer */
97 : int nbytes; /* total # of valid bytes in buffer */
98 :
99 : /*
100 : * XXX Should ideally us 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 8500 : makeBufFileCommon(int nfiles)
119 : {
120 8500 : BufFile *file = (BufFile *) palloc(sizeof(BufFile));
121 :
122 8500 : file->numFiles = nfiles;
123 8500 : file->isInterXact = false;
124 8500 : file->dirty = false;
125 8500 : file->resowner = CurrentResourceOwner;
126 8500 : file->curFile = 0;
127 8500 : file->curOffset = 0;
128 8500 : file->pos = 0;
129 8500 : file->nbytes = 0;
130 :
131 8500 : 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 3064 : makeBufFile(File firstfile)
140 : {
141 3064 : BufFile *file = makeBufFileCommon(1);
142 :
143 3064 : file->files = (File *) palloc(sizeof(File));
144 3064 : file->files[0] = firstfile;
145 3064 : file->readOnly = false;
146 3064 : file->fileset = NULL;
147 3064 : file->name = NULL;
148 :
149 3064 : 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 3064 : 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 3064 : PrepareTempTablespaces();
208 :
209 3064 : pfile = OpenTemporaryFile(interXact);
210 : Assert(pfile >= 0);
211 :
212 3064 : file = makeBufFile(pfile);
213 3064 : file->isInterXact = interXact;
214 :
215 3064 : return file;
216 : }
217 :
218 : /*
219 : * Build the name for a given segment of a given BufFile.
220 : */
221 : static void
222 12200 : FileSetSegmentName(char *name, const char *buffile_name, int segment)
223 : {
224 12200 : snprintf(name, MAXPGPATH, "%s.%d", buffile_name, segment);
225 12200 : }
226 :
227 : /*
228 : * Create a new segment file backing a fileset based BufFile.
229 : */
230 : static File
231 2270 : 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 2270 : FileSetSegmentName(name, buffile->name, segment + 1);
243 2270 : FileSetDelete(buffile->fileset, name, true);
244 :
245 : /* Create the new segment. */
246 2270 : FileSetSegmentName(name, buffile->name, segment);
247 2270 : file = FileSetCreate(buffile->fileset, name);
248 :
249 : /* FileSetCreate would've errored out */
250 : Assert(file > 0);
251 :
252 2270 : 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 2270 : BufFileCreateFileSet(FileSet *fileset, const char *name)
268 : {
269 : BufFile *file;
270 :
271 2270 : file = makeBufFileCommon(1);
272 2270 : file->fileset = fileset;
273 2270 : file->name = pstrdup(name);
274 2270 : file->files = (File *) palloc(sizeof(File));
275 2270 : file->files[0] = MakeNewFileSetSegment(file, 0);
276 2270 : file->readOnly = false;
277 :
278 2270 : 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 3712 : BufFileOpenFileSet(FileSet *fileset, const char *name, int mode,
292 : bool missing_ok)
293 : {
294 : BufFile *file;
295 : char segment_name[MAXPGPATH];
296 3712 : Size capacity = 16;
297 : File *files;
298 3712 : int nfiles = 0;
299 :
300 3712 : files = palloc(sizeof(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 6878 : if (nfiles + 1 > capacity)
310 : {
311 0 : capacity *= 2;
312 0 : files = repalloc(files, sizeof(File) * capacity);
313 : }
314 : /* Try to load a segment. */
315 6878 : FileSetSegmentName(segment_name, name, nfiles);
316 6878 : files[nfiles] = FileSetOpen(fileset, segment_name, mode);
317 6878 : if (files[nfiles] <= 0)
318 3712 : break;
319 3166 : ++nfiles;
320 :
321 3166 : 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 3712 : if (nfiles == 0)
329 : {
330 : /* free the memory */
331 546 : pfree(files);
332 :
333 546 : if (missing_ok)
334 546 : 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 3166 : file = makeBufFileCommon(nfiles);
343 3166 : file->files = files;
344 3166 : file->readOnly = (mode == O_RDONLY);
345 3166 : file->fileset = fileset;
346 3166 : file->name = pstrdup(name);
347 :
348 3166 : 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
364 704 : BufFileDeleteFileSet(FileSet *fileset, const char *name, bool missing_ok)
365 : {
366 : char segment_name[MAXPGPATH];
367 704 : int segment = 0;
368 704 : 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 : {
377 782 : FileSetSegmentName(segment_name, name, segment);
378 782 : if (!FileSetDelete(fileset, segment_name, true))
379 704 : break;
380 78 : found = true;
381 78 : ++segment;
382 :
383 78 : CHECK_FOR_INTERRUPTS();
384 : }
385 :
386 704 : if (!found && !missing_ok)
387 0 : elog(ERROR, "could not delete unknown BufFile \"%s\"", name);
388 704 : }
389 :
390 : /*
391 : * BufFileExportFileSet --- flush and make read-only, in preparation for sharing.
392 : */
393 : void
394 444 : 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 :
402 444 : BufFileFlush(file);
403 444 : file->readOnly = true;
404 444 : }
405 :
406 : /*
407 : * Close a BufFile
408 : *
409 : * Like fclose(), this also implicitly FileCloses the underlying File.
410 : */
411 : void
412 8322 : BufFileClose(BufFile *file)
413 : {
414 : int i;
415 :
416 : /* flush any unwritten data */
417 8322 : BufFileFlush(file);
418 : /* close and delete the underlying file(s) */
419 16804 : for (i = 0; i < file->numFiles; i++)
420 8482 : FileClose(file->files[i]);
421 : /* release the buffer space */
422 8322 : pfree(file->files);
423 8322 : pfree(file);
424 8322 : }
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 93888 : 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 93888 : 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 93888 : thisfile = file->files[file->curFile];
451 :
452 93888 : if (track_io_timing)
453 0 : INSTR_TIME_SET_CURRENT(io_start);
454 : else
455 93888 : INSTR_TIME_SET_ZERO(io_start);
456 :
457 : /*
458 : * Read whatever we can get, up to a full bufferload.
459 : */
460 187776 : file->nbytes = FileRead(thisfile,
461 93888 : file->buffer.data,
462 : sizeof(file->buffer),
463 : file->curOffset,
464 : WAIT_EVENT_BUFFILE_READ);
465 93888 : 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 93888 : 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 93888 : if (file->nbytes > 0)
483 91280 : pgBufferUsage.temp_blks_read++;
484 93888 : }
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 105230 : BufFileDumpBuffer(BufFile *file)
495 : {
496 105230 : int wpos = 0;
497 : int 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 210460 : while (wpos < file->nbytes)
505 : {
506 : off_t 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 105230 : 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 105230 : bytestowrite = file->nbytes - wpos;
525 105230 : availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset;
526 :
527 105230 : if ((off_t) bytestowrite > availbytes)
528 0 : bytestowrite = (int) availbytes;
529 :
530 105230 : thisfile = file->files[file->curFile];
531 :
532 105230 : if (track_io_timing)
533 0 : INSTR_TIME_SET_CURRENT(io_start);
534 : else
535 105230 : INSTR_TIME_SET_ZERO(io_start);
536 :
537 210460 : bytestowrite = FileWrite(thisfile,
538 105230 : file->buffer.data + wpos,
539 : bytestowrite,
540 : file->curOffset,
541 : WAIT_EVENT_BUFFILE_WRITE);
542 105230 : 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 105230 : 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 105230 : file->curOffset += bytestowrite;
555 105230 : wpos += bytestowrite;
556 :
557 105230 : pgBufferUsage.temp_blks_written++;
558 : }
559 105230 : 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 105230 : file->curOffset -= (file->nbytes - file->pos);
568 105230 : 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 105230 : file->pos = 0;
579 105230 : file->nbytes = 0;
580 105230 : }
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 23305184 : BufFileReadCommon(BufFile *file, void *ptr, size_t size, bool exact, bool eofOK)
594 : {
595 23305184 : size_t start_size = size;
596 23305184 : size_t nread = 0;
597 : size_t nthistime;
598 :
599 23305184 : BufFileFlush(file);
600 :
601 46633590 : while (size > 0)
602 : {
603 23331014 : if (file->pos >= file->nbytes)
604 : {
605 : /* Try to load more data into buffer. */
606 93888 : file->curOffset += file->pos;
607 93888 : file->pos = 0;
608 93888 : file->nbytes = 0;
609 93888 : BufFileLoadBuffer(file);
610 93888 : if (file->nbytes <= 0)
611 2608 : break; /* no more data available */
612 : }
613 :
614 23328406 : nthistime = file->nbytes - file->pos;
615 23328406 : if (nthistime > size)
616 23239646 : nthistime = size;
617 : Assert(nthistime > 0);
618 :
619 23328406 : memcpy(ptr, file->buffer.data + file->pos, nthistime);
620 :
621 23328406 : file->pos += nthistime;
622 23328406 : ptr = (char *) ptr + nthistime;
623 23328406 : size -= nthistime;
624 23328406 : nread += nthistime;
625 : }
626 :
627 23305184 : if (exact &&
628 2608 : (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 23305184 : 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 15343902 : BufFileReadExact(BufFile *file, void *ptr, size_t size)
655 : {
656 15343902 : BufFileReadCommon(file, ptr, size, true, false);
657 15343902 : }
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 7961282 : BufFileReadMaybeEOF(BufFile *file, void *ptr, size_t size, bool eofOK)
665 : {
666 7961282 : 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 22578518 : BufFileWrite(BufFile *file, const void *ptr, size_t size)
677 : {
678 : size_t nthistime;
679 :
680 : Assert(!file->readOnly);
681 :
682 45197644 : while (size > 0)
683 : {
684 22619126 : if (file->pos >= BLCKSZ)
685 : {
686 : /* Buffer full, dump it out */
687 66832 : if (file->dirty)
688 66364 : BufFileDumpBuffer(file);
689 : else
690 : {
691 : /* Hmm, went directly from reading to writing? */
692 468 : file->curOffset += file->pos;
693 468 : file->pos = 0;
694 468 : file->nbytes = 0;
695 : }
696 : }
697 :
698 22619126 : nthistime = BLCKSZ - file->pos;
699 22619126 : if (nthistime > size)
700 22517650 : nthistime = size;
701 : Assert(nthistime > 0);
702 :
703 22619126 : memcpy(file->buffer.data + file->pos, ptr, nthistime);
704 :
705 22619126 : file->dirty = true;
706 22619126 : file->pos += nthistime;
707 22619126 : if (file->nbytes < file->pos)
708 22615262 : file->nbytes = file->pos;
709 22619126 : ptr = (const char *) ptr + nthistime;
710 22619126 : size -= nthistime;
711 : }
712 22578518 : }
713 :
714 : /*
715 : * BufFileFlush
716 : *
717 : * Like fflush(), except that I/O errors are reported with ereport().
718 : */
719 : static void
720 23365474 : BufFileFlush(BufFile *file)
721 : {
722 23365474 : if (file->dirty)
723 38866 : BufFileDumpBuffer(file);
724 :
725 : Assert(!file->dirty);
726 23365474 : }
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 off_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 104732 : BufFileSeek(BufFile *file, int fileno, off_t offset, int whence)
741 : {
742 : int newFile;
743 : off_t newOffset;
744 :
745 104732 : switch (whence)
746 : {
747 104062 : case SEEK_SET:
748 104062 : if (fileno < 0)
749 0 : return EOF;
750 104062 : newFile = fileno;
751 104062 : newOffset = offset;
752 104062 : break;
753 0 : case SEEK_CUR:
754 :
755 : /*
756 : * Relative seek considers only the signed offset, ignoring
757 : * fileno. Note that large offsets (> 1 GB) risk overflow in this
758 : * add, unless we have 64-bit off_t.
759 : */
760 0 : newFile = file->curFile;
761 0 : newOffset = (file->curOffset + file->pos) + offset;
762 0 : break;
763 670 : case SEEK_END:
764 :
765 : /*
766 : * The file size of the last file gives us the end offset of that
767 : * file.
768 : */
769 670 : newFile = file->numFiles - 1;
770 670 : newOffset = FileSize(file->files[file->numFiles - 1]);
771 670 : if (newOffset < 0)
772 0 : ereport(ERROR,
773 : (errcode_for_file_access(),
774 : errmsg("could not determine size of temporary file \"%s\" from BufFile \"%s\": %m",
775 : FilePathName(file->files[file->numFiles - 1]),
776 : file->name)));
777 670 : break;
778 0 : default:
779 0 : elog(ERROR, "invalid whence: %d", whence);
780 : return EOF;
781 : }
782 104732 : while (newOffset < 0)
783 : {
784 0 : if (--newFile < 0)
785 0 : return EOF;
786 0 : newOffset += MAX_PHYSICAL_FILESIZE;
787 : }
788 104732 : if (newFile == file->curFile &&
789 104572 : newOffset >= file->curOffset &&
790 76422 : newOffset <= file->curOffset + file->nbytes)
791 : {
792 : /*
793 : * Seek is to a point within existing buffer; we can just adjust
794 : * pos-within-buffer, without flushing buffer. Note this is OK
795 : * whether reading or writing, but buffer remains dirty if we were
796 : * writing.
797 : */
798 53208 : file->pos = (int) (newOffset - file->curOffset);
799 53208 : return 0;
800 : }
801 : /* Otherwise, must reposition buffer, so flush any dirty data */
802 51524 : BufFileFlush(file);
803 :
804 : /*
805 : * At this point and no sooner, check for seek past last segment. The
806 : * above flush could have created a new segment, so checking sooner would
807 : * not work (at least not with this code).
808 : */
809 :
810 : /* convert seek to "start of next seg" to "end of last seg" */
811 51524 : if (newFile == file->numFiles && newOffset == 0)
812 : {
813 0 : newFile--;
814 0 : newOffset = MAX_PHYSICAL_FILESIZE;
815 : }
816 51524 : while (newOffset > MAX_PHYSICAL_FILESIZE)
817 : {
818 0 : if (++newFile >= file->numFiles)
819 0 : return EOF;
820 0 : newOffset -= MAX_PHYSICAL_FILESIZE;
821 : }
822 51524 : if (newFile >= file->numFiles)
823 0 : return EOF;
824 : /* Seek is OK! */
825 51524 : file->curFile = newFile;
826 51524 : file->curOffset = newOffset;
827 51524 : file->pos = 0;
828 51524 : file->nbytes = 0;
829 51524 : return 0;
830 : }
831 :
832 : void
833 177232 : BufFileTell(BufFile *file, int *fileno, off_t *offset)
834 : {
835 177232 : *fileno = file->curFile;
836 177232 : *offset = file->curOffset + file->pos;
837 177232 : }
838 :
839 : /*
840 : * BufFileSeekBlock --- block-oriented seek
841 : *
842 : * Performs absolute seek to the start of the n'th BLCKSZ-sized block of
843 : * the file. Note that users of this interface will fail if their files
844 : * exceed BLCKSZ * PG_INT64_MAX bytes, but that is quite a lot; we don't
845 : * work with tables bigger than that, either...
846 : *
847 : * Result is 0 if OK, EOF if not. Logical position is not moved if an
848 : * impossible seek is attempted.
849 : */
850 : int
851 101156 : BufFileSeekBlock(BufFile *file, int64 blknum)
852 : {
853 202312 : return BufFileSeek(file,
854 101156 : (int) (blknum / BUFFILE_SEG_SIZE),
855 101156 : (off_t) (blknum % BUFFILE_SEG_SIZE) * BLCKSZ,
856 : SEEK_SET);
857 : }
858 :
859 : /*
860 : * Returns the amount of data in the given BufFile, in bytes.
861 : *
862 : * Returned value includes the size of any holes left behind by BufFileAppend.
863 : * ereport()s on failure.
864 : */
865 : int64
866 328 : BufFileSize(BufFile *file)
867 : {
868 : int64 lastFileSize;
869 :
870 : /* Get the size of the last physical file. */
871 328 : lastFileSize = FileSize(file->files[file->numFiles - 1]);
872 328 : if (lastFileSize < 0)
873 0 : ereport(ERROR,
874 : (errcode_for_file_access(),
875 : errmsg("could not determine size of temporary file \"%s\" from BufFile \"%s\": %m",
876 : FilePathName(file->files[file->numFiles - 1]),
877 : file->name)));
878 :
879 328 : return ((file->numFiles - 1) * (int64) MAX_PHYSICAL_FILESIZE) +
880 : lastFileSize;
881 : }
882 :
883 : /*
884 : * Append the contents of the source file to the end of the target file.
885 : *
886 : * Note that operation subsumes ownership of underlying resources from
887 : * "source". Caller should never call BufFileClose against source having
888 : * called here first. Resource owners for source and target must match,
889 : * too.
890 : *
891 : * This operation works by manipulating lists of segment files, so the
892 : * file content is always appended at a MAX_PHYSICAL_FILESIZE-aligned
893 : * boundary, typically creating empty holes before the boundary. These
894 : * areas do not contain any interesting data, and cannot be read from by
895 : * caller.
896 : *
897 : * Returns the block number within target where the contents of source
898 : * begins. Caller should apply this as an offset when working off block
899 : * positions that are in terms of the original BufFile space.
900 : */
901 : int64
902 160 : BufFileAppend(BufFile *target, BufFile *source)
903 : {
904 160 : int64 startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;
905 160 : int newNumFiles = target->numFiles + source->numFiles;
906 : int i;
907 :
908 : Assert(source->readOnly);
909 : Assert(!source->dirty);
910 :
911 160 : if (target->resowner != source->resowner)
912 0 : elog(ERROR, "could not append BufFile with non-matching resource owner");
913 :
914 160 : target->files = (File *)
915 160 : repalloc(target->files, sizeof(File) * newNumFiles);
916 320 : for (i = target->numFiles; i < newNumFiles; i++)
917 160 : target->files[i] = source->files[i - target->numFiles];
918 160 : target->numFiles = newNumFiles;
919 :
920 160 : return startBlock;
921 : }
922 :
923 : /*
924 : * Truncate a BufFile created by BufFileCreateFileSet up to the given fileno
925 : * and the offset.
926 : */
927 : void
928 18 : BufFileTruncateFileSet(BufFile *file, int fileno, off_t offset)
929 : {
930 18 : int numFiles = file->numFiles;
931 18 : int newFile = fileno;
932 18 : off_t newOffset = file->curOffset;
933 : char segment_name[MAXPGPATH];
934 : int i;
935 :
936 : /*
937 : * Loop over all the files up to the given fileno and remove the files
938 : * that are greater than the fileno and truncate the given file up to the
939 : * offset. Note that we also remove the given fileno if the offset is 0
940 : * provided it is not the first file in which we truncate it.
941 : */
942 36 : for (i = file->numFiles - 1; i >= fileno; i--)
943 : {
944 18 : if ((i != fileno || offset == 0) && i != 0)
945 : {
946 0 : FileSetSegmentName(segment_name, file->name, i);
947 0 : FileClose(file->files[i]);
948 0 : if (!FileSetDelete(file->fileset, segment_name, true))
949 0 : ereport(ERROR,
950 : (errcode_for_file_access(),
951 : errmsg("could not delete fileset \"%s\": %m",
952 : segment_name)));
953 0 : numFiles--;
954 0 : newOffset = MAX_PHYSICAL_FILESIZE;
955 :
956 : /*
957 : * This is required to indicate that we have deleted the given
958 : * fileno.
959 : */
960 0 : if (i == fileno)
961 0 : newFile--;
962 : }
963 : else
964 : {
965 18 : if (FileTruncate(file->files[i], offset,
966 : WAIT_EVENT_BUFFILE_TRUNCATE) < 0)
967 0 : ereport(ERROR,
968 : (errcode_for_file_access(),
969 : errmsg("could not truncate file \"%s\": %m",
970 : FilePathName(file->files[i]))));
971 18 : newOffset = offset;
972 : }
973 : }
974 :
975 18 : file->numFiles = numFiles;
976 :
977 : /*
978 : * If the truncate point is within existing buffer then we can just adjust
979 : * pos within buffer.
980 : */
981 18 : if (newFile == file->curFile &&
982 18 : newOffset >= file->curOffset &&
983 18 : newOffset <= file->curOffset + file->nbytes)
984 : {
985 : /* No need to reset the current pos if the new pos is greater. */
986 0 : if (newOffset <= file->curOffset + file->pos)
987 0 : file->pos = (int) (newOffset - file->curOffset);
988 :
989 : /* Adjust the nbytes for the current buffer. */
990 0 : file->nbytes = (int) (newOffset - file->curOffset);
991 : }
992 18 : else if (newFile == file->curFile &&
993 18 : newOffset < file->curOffset)
994 : {
995 : /*
996 : * The truncate point is within the existing file but prior to the
997 : * current position, so we can forget the current buffer and reset the
998 : * current position.
999 : */
1000 0 : file->curOffset = newOffset;
1001 0 : file->pos = 0;
1002 0 : file->nbytes = 0;
1003 : }
1004 18 : else if (newFile < file->curFile)
1005 : {
1006 : /*
1007 : * The truncate point is prior to the current file, so need to reset
1008 : * the current position accordingly.
1009 : */
1010 0 : file->curFile = newFile;
1011 0 : file->curOffset = newOffset;
1012 0 : file->pos = 0;
1013 0 : file->nbytes = 0;
1014 : }
1015 : /* Nothing to do, if the truncate point is beyond current file. */
1016 18 : }
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