Branch data 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 : 1366 : makeBufFileCommon(int nfiles)
119 : : {
120 : 1366 : BufFile *file = palloc_object(BufFile);
121 : :
122 : 1366 : file->numFiles = nfiles;
123 : 1366 : file->isInterXact = false;
124 : 1366 : file->dirty = false;
125 : 1366 : file->resowner = CurrentResourceOwner;
126 : 1366 : file->curFile = 0;
127 : 1366 : file->curOffset = 0;
128 : 1366 : file->pos = 0;
129 : 1366 : file->nbytes = 0;
130 : :
131 : 2732 : return file;
132 : 1366 : }
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 : 485 : makeBufFile(File firstfile)
140 : : {
141 : 485 : BufFile *file = makeBufFileCommon(1);
142 : :
143 : 485 : file->files = palloc_object(File);
144 : 485 : file->files[0] = firstfile;
145 : 485 : file->readOnly = false;
146 : 485 : file->fileset = NULL;
147 : 485 : file->name = NULL;
148 : :
149 : 970 : return file;
150 : 485 : }
151 : :
152 : : /*
153 : : * Add another component temp file.
154 : : */
155 : : static void
156 : 0 : extendBufFile(BufFile *file)
157 : : {
158 : 0 : File pfile;
159 : 0 : 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 [ # # ]: 0 : 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 : 485 : BufFileCreateTemp(bool interXact)
194 : : {
195 : 485 : BufFile *file;
196 : 485 : 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 : 485 : PrepareTempTablespaces();
208 : :
209 : 485 : pfile = OpenTemporaryFile(interXact);
210 [ + - ]: 485 : Assert(pfile >= 0);
211 : :
212 : 485 : file = makeBufFile(pfile);
213 : 485 : file->isInterXact = interXact;
214 : :
215 : 970 : return file;
216 : 485 : }
217 : :
218 : : /*
219 : : * Build the name for a given segment of a given BufFile.
220 : : */
221 : : static void
222 : 1762 : FileSetSegmentName(char *name, const char *buffile_name, int segment)
223 : : {
224 : 1762 : snprintf(name, MAXPGPATH, "%s.%d", buffile_name, segment);
225 : 1762 : }
226 : :
227 : : /*
228 : : * Create a new segment file backing a fileset based BufFile.
229 : : */
230 : : static File
231 : 448 : MakeNewFileSetSegment(BufFile *buffile, int segment)
232 : : {
233 : 448 : char name[MAXPGPATH];
234 : 448 : 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 : 448 : FileSetSegmentName(name, buffile->name, segment + 1);
243 : 448 : FileSetDelete(buffile->fileset, name, true);
244 : :
245 : : /* Create the new segment. */
246 : 448 : FileSetSegmentName(name, buffile->name, segment);
247 : 448 : file = FileSetCreate(buffile->fileset, name);
248 : :
249 : : /* FileSetCreate would've errored out */
250 [ + - ]: 448 : Assert(file > 0);
251 : :
252 : 896 : return file;
253 : 448 : }
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 : 448 : BufFileCreateFileSet(FileSet *fileset, const char *name)
268 : : {
269 : 448 : BufFile *file;
270 : :
271 : 448 : file = makeBufFileCommon(1);
272 : 448 : file->fileset = fileset;
273 : 448 : file->name = pstrdup(name);
274 : 448 : file->files = palloc_object(File);
275 : 448 : file->files[0] = MakeNewFileSetSegment(file, 0);
276 : 448 : file->readOnly = false;
277 : :
278 : 896 : return file;
279 : 448 : }
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 : 433 : BufFileOpenFileSet(FileSet *fileset, const char *name, int mode,
292 : : bool missing_ok)
293 : : {
294 : 433 : BufFile *file;
295 : 433 : char segment_name[MAXPGPATH];
296 : 433 : Size capacity = 16;
297 : 433 : File *files;
298 : 433 : int nfiles = 0;
299 : :
300 : 433 : 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 : 866 : for (;;)
307 : : {
308 : : /* See if we need to expand our file segment array. */
309 [ + - ]: 866 : if (nfiles + 1 > capacity)
310 : : {
311 : 0 : capacity *= 2;
312 : 0 : files = repalloc_array(files, File, capacity);
313 : 0 : }
314 : : /* Try to load a segment. */
315 : 866 : FileSetSegmentName(segment_name, name, nfiles);
316 : 866 : files[nfiles] = FileSetOpen(fileset, segment_name, mode);
317 [ + + ]: 866 : if (files[nfiles] <= 0)
318 : 433 : break;
319 : 433 : ++nfiles;
320 : :
321 [ + + ]: 433 : 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 [ + - ]: 433 : if (nfiles == 0)
329 : : {
330 : : /* free the memory */
331 : 0 : pfree(files);
332 : :
333 [ # # ]: 0 : if (missing_ok)
334 : 0 : 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 : 0 : }
341 : :
342 : 433 : file = makeBufFileCommon(nfiles);
343 : 433 : file->files = files;
344 : 433 : file->readOnly = (mode == O_RDONLY);
345 : 433 : file->fileset = fileset;
346 : 433 : file->name = pstrdup(name);
347 : :
348 : 433 : return file;
349 : 433 : }
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 : 0 : BufFileDeleteFileSet(FileSet *fileset, const char *name, bool missing_ok)
365 : : {
366 : 0 : char segment_name[MAXPGPATH];
367 : 0 : int segment = 0;
368 : 0 : 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 : 0 : for (;;)
376 : : {
377 : 0 : FileSetSegmentName(segment_name, name, segment);
378 [ # # ]: 0 : if (!FileSetDelete(fileset, segment_name, true))
379 : 0 : break;
380 : 0 : found = true;
381 : 0 : ++segment;
382 : :
383 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
384 : : }
385 : :
386 [ # # # # ]: 0 : if (!found && !missing_ok)
387 [ # # # # ]: 0 : elog(ERROR, "could not delete unknown BufFile \"%s\"", name);
388 : 0 : }
389 : :
390 : : /*
391 : : * BufFileExportFileSet --- flush and make read-only, in preparation for sharing.
392 : : */
393 : : void
394 : 82 : BufFileExportFileSet(BufFile *file)
395 : : {
396 : : /* Must be a file belonging to a FileSet. */
397 [ + - ]: 82 : Assert(file->fileset != NULL);
398 : :
399 : : /* It's probably a bug if someone calls this twice. */
400 [ + - ]: 82 : Assert(!file->readOnly);
401 : :
402 : 82 : BufFileFlush(file);
403 : 82 : file->readOnly = true;
404 : 82 : }
405 : :
406 : : /*
407 : : * Close a BufFile
408 : : *
409 : : * Like fclose(), this also implicitly FileCloses the underlying File.
410 : : */
411 : : void
412 : 1338 : BufFileClose(BufFile *file)
413 : : {
414 : 1338 : int i;
415 : :
416 : : /* flush any unwritten data */
417 : 1338 : BufFileFlush(file);
418 : : /* close and delete the underlying file(s) */
419 [ + + ]: 2704 : for (i = 0; i < file->numFiles; i++)
420 : 1366 : FileClose(file->files[i]);
421 : : /* release the buffer space */
422 : 1338 : pfree(file->files);
423 : 1338 : pfree(file);
424 : 1338 : }
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 : 34558 : BufFileLoadBuffer(BufFile *file)
435 : : {
436 : 34558 : File thisfile;
437 : 34558 : instr_time io_start;
438 : 34558 : instr_time io_time;
439 : :
440 : : /*
441 : : * Advance to next component file if necessary and possible.
442 : : */
443 [ - + # # ]: 34558 : if (file->curOffset >= MAX_PHYSICAL_FILESIZE &&
444 : 0 : file->curFile + 1 < file->numFiles)
445 : : {
446 : 0 : file->curFile++;
447 : 0 : file->curOffset = 0;
448 : 0 : }
449 : :
450 : 34558 : thisfile = file->files[file->curFile];
451 : :
452 [ - + ]: 34558 : if (track_io_timing)
453 : 0 : INSTR_TIME_SET_CURRENT(io_start);
454 : : else
455 : 34558 : INSTR_TIME_SET_ZERO(io_start);
456 : :
457 : : /*
458 : : * Read whatever we can get, up to a full bufferload.
459 : : */
460 : 69116 : file->nbytes = FileRead(thisfile,
461 : 34558 : file->buffer.data,
462 : : sizeof(file->buffer.data),
463 : 34558 : file->curOffset,
464 : : WAIT_EVENT_BUFFILE_READ);
465 [ + - ]: 34558 : 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 : 0 : }
473 : :
474 [ + - ]: 34558 : 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 : 0 : }
479 : :
480 : : /* we choose not to advance curOffset here */
481 : :
482 [ + + ]: 34558 : if (file->nbytes > 0)
483 : 34106 : pgBufferUsage.temp_blks_read++;
484 : 34558 : }
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 : 35453 : BufFileDumpBuffer(BufFile *file)
495 : : {
496 : 35453 : int64 wpos = 0;
497 : 35453 : int64 bytestowrite;
498 : 35453 : 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 [ + + ]: 70906 : while (wpos < file->nbytes)
505 : : {
506 : 35453 : int64 availbytes;
507 : 35453 : instr_time io_start;
508 : 35453 : instr_time io_time;
509 : :
510 : : /*
511 : : * Advance to next component file if necessary and possible.
512 : : */
513 [ + - ]: 35453 : 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 : 0 : }
520 : :
521 : : /*
522 : : * Determine how much we need to write into this file.
523 : : */
524 : 35453 : bytestowrite = file->nbytes - wpos;
525 : 35453 : availbytes = MAX_PHYSICAL_FILESIZE - file->curOffset;
526 : :
527 [ + - ]: 35453 : if (bytestowrite > availbytes)
528 : 0 : bytestowrite = availbytes;
529 : :
530 : 35453 : thisfile = file->files[file->curFile];
531 : :
532 [ - + ]: 35453 : if (track_io_timing)
533 : 0 : INSTR_TIME_SET_CURRENT(io_start);
534 : : else
535 : 35453 : INSTR_TIME_SET_ZERO(io_start);
536 : :
537 : 70906 : bytestowrite = FileWrite(thisfile,
538 : 35453 : file->buffer.data + wpos,
539 : 35453 : bytestowrite,
540 : 35453 : file->curOffset,
541 : : WAIT_EVENT_BUFFILE_WRITE);
542 [ + - ]: 35453 : 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 [ - + ]: 35453 : 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 : 0 : }
553 : :
554 : 35453 : file->curOffset += bytestowrite;
555 : 35453 : wpos += bytestowrite;
556 : :
557 : 35453 : pgBufferUsage.temp_blks_written++;
558 : 35453 : }
559 : 35453 : 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 : 35453 : file->curOffset -= (file->nbytes - file->pos);
568 [ + - ]: 35453 : if (file->curOffset < 0) /* handle possible segment crossing */
569 : : {
570 : 0 : file->curFile--;
571 [ # # ]: 0 : Assert(file->curFile >= 0);
572 : 0 : file->curOffset += MAX_PHYSICAL_FILESIZE;
573 : 0 : }
574 : :
575 : : /*
576 : : * Now we can set the buffer empty without changing the logical position
577 : : */
578 : 35453 : file->pos = 0;
579 : 35453 : file->nbytes = 0;
580 : 35453 : }
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 : 5404465 : BufFileReadCommon(BufFile *file, void *ptr, size_t size, bool exact, bool eofOK)
594 : : {
595 : 5404465 : size_t start_size = size;
596 : 5404465 : size_t nread = 0;
597 : 5404465 : size_t nthistime;
598 : :
599 : 5404465 : BufFileFlush(file);
600 : :
601 [ + + ]: 10832062 : while (size > 0)
602 : : {
603 [ + + ]: 5428049 : if (file->pos >= file->nbytes)
604 : : {
605 : : /* Try to load more data into buffer. */
606 : 34558 : file->curOffset += file->pos;
607 : 34558 : file->pos = 0;
608 : 34558 : file->nbytes = 0;
609 : 34558 : BufFileLoadBuffer(file);
610 [ + + ]: 34558 : if (file->nbytes <= 0)
611 : 452 : break; /* no more data available */
612 : 34106 : }
613 : :
614 : 5427597 : nthistime = file->nbytes - file->pos;
615 [ + + ]: 5427597 : if (nthistime > size)
616 : 5393985 : nthistime = size;
617 [ - + ]: 5427597 : Assert(nthistime > 0);
618 : :
619 : 5427597 : memcpy(ptr, file->buffer.data + file->pos, nthistime);
620 : :
621 : 5427597 : file->pos += nthistime;
622 : 5427597 : ptr = (char *) ptr + nthistime;
623 : 5427597 : size -= nthistime;
624 : 5427597 : nread += nthistime;
625 : : }
626 : :
627 [ + - ]: 5404917 : if (exact &&
628 [ + + + - ]: 5404465 : (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 : 10808930 : return nread;
638 : 5404465 : }
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 : 3316558 : BufFileReadExact(BufFile *file, void *ptr, size_t size)
655 : : {
656 : 3316558 : BufFileReadCommon(file, ptr, size, true, false);
657 : 3316558 : }
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 : 2087907 : BufFileReadMaybeEOF(BufFile *file, void *ptr, size_t size, bool eofOK)
665 : : {
666 : 2087907 : 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 : 4197667 : BufFileWrite(BufFile *file, const void *ptr, size_t size)
677 : : {
678 : 4197667 : size_t nthistime;
679 : :
680 [ + - ]: 4197667 : Assert(!file->readOnly);
681 : :
682 [ + + ]: 8420888 : while (size > 0)
683 : : {
684 [ + + ]: 4223221 : if (file->pos >= BLCKSZ)
685 : : {
686 : : /* Buffer full, dump it out */
687 [ + + ]: 29135 : if (file->dirty)
688 : 29057 : BufFileDumpBuffer(file);
689 : : else
690 : : {
691 : : /* Hmm, went directly from reading to writing? */
692 : 78 : file->curOffset += file->pos;
693 : 78 : file->pos = 0;
694 : 78 : file->nbytes = 0;
695 : : }
696 : 29135 : }
697 : :
698 : 4223221 : nthistime = BLCKSZ - file->pos;
699 [ + + ]: 4223221 : if (nthistime > size)
700 : 4188225 : nthistime = size;
701 [ + - ]: 4223221 : Assert(nthistime > 0);
702 : :
703 : 4223221 : memcpy(file->buffer.data + file->pos, ptr, nthistime);
704 : :
705 : 4223221 : file->dirty = true;
706 : 4223221 : file->pos += nthistime;
707 [ + + ]: 4223221 : if (file->nbytes < file->pos)
708 : 4222577 : file->nbytes = file->pos;
709 : 4223221 : ptr = (const char *) ptr + nthistime;
710 : 4223221 : size -= nthistime;
711 : : }
712 : 4197667 : }
713 : :
714 : : /*
715 : : * BufFileFlush
716 : : *
717 : : * Like fflush(), except that I/O errors are reported with ereport().
718 : : */
719 : : static void
720 : 5414352 : BufFileFlush(BufFile *file)
721 : : {
722 [ + + ]: 5414352 : if (file->dirty)
723 : 6396 : BufFileDumpBuffer(file);
724 : :
725 [ + - ]: 5414352 : Assert(!file->dirty);
726 : 5414352 : }
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 : 15603 : BufFileSeek(BufFile *file, int fileno, pgoff_t offset, int whence)
741 : : {
742 : 15603 : int newFile;
743 : 15603 : pgoff_t newOffset;
744 : :
745 [ - + - - ]: 15603 : switch (whence)
746 : : {
747 : : case SEEK_SET:
748 [ + - ]: 15603 : if (fileno < 0)
749 : 0 : return EOF;
750 : 15603 : newFile = fileno;
751 : 15603 : newOffset = offset;
752 : 15603 : break;
753 : : 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 : : case SEEK_END:
763 : :
764 : : /*
765 : : * The file size of the last file gives us the end offset of that
766 : : * file.
767 : : */
768 : 0 : newFile = file->numFiles - 1;
769 : 0 : newOffset = FileSize(file->files[file->numFiles - 1]);
770 [ # # ]: 0 : 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 : 0 : break;
777 : : default:
778 [ # # # # ]: 0 : elog(ERROR, "invalid whence: %d", whence);
779 : 0 : return EOF;
780 : : }
781 [ - + ]: 15603 : while (newOffset < 0)
782 : : {
783 [ # # ]: 0 : if (--newFile < 0)
784 : 0 : return EOF;
785 : 0 : newOffset += MAX_PHYSICAL_FILESIZE;
786 : : }
787 [ + + ]: 15603 : if (newFile == file->curFile &&
788 [ + + + + ]: 15575 : newOffset >= file->curOffset &&
789 : 10916 : 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 : 7136 : file->pos = (int64) (newOffset - file->curOffset);
798 : 7136 : return 0;
799 : : }
800 : : /* Otherwise, must reposition buffer, so flush any dirty data */
801 : 8467 : 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 [ - + # # ]: 8467 : if (newFile == file->numFiles && newOffset == 0)
811 : : {
812 : 0 : newFile--;
813 : 0 : newOffset = MAX_PHYSICAL_FILESIZE;
814 : 0 : }
815 [ - + ]: 8467 : while (newOffset > MAX_PHYSICAL_FILESIZE)
816 : : {
817 [ # # ]: 0 : if (++newFile >= file->numFiles)
818 : 0 : return EOF;
819 : 0 : newOffset -= MAX_PHYSICAL_FILESIZE;
820 : : }
821 [ - + ]: 8467 : if (newFile >= file->numFiles)
822 : 0 : return EOF;
823 : : /* Seek is OK! */
824 : 8467 : file->curFile = newFile;
825 : 8467 : file->curOffset = newOffset;
826 : 8467 : file->pos = 0;
827 : 8467 : file->nbytes = 0;
828 : 8467 : return 0;
829 : 15603 : }
830 : :
831 : : void
832 : 90 : BufFileTell(BufFile *file, int *fileno, pgoff_t *offset)
833 : : {
834 : 90 : *fileno = file->curFile;
835 : 90 : *offset = file->curOffset + file->pos;
836 : 90 : }
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 : 15142 : BufFileSeekBlock(BufFile *file, int64 blknum)
851 : : {
852 : 30284 : return BufFileSeek(file,
853 : 15142 : (int) (blknum / BUFFILE_SEG_SIZE),
854 : 15142 : (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 : 58 : BufFileSize(BufFile *file)
866 : : {
867 : 58 : int64 lastFileSize;
868 : :
869 : : /* Get the size of the last physical file. */
870 : 58 : lastFileSize = FileSize(file->files[file->numFiles - 1]);
871 [ + - ]: 58 : 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 : 174 : return ((file->numFiles - 1) * (int64) MAX_PHYSICAL_FILESIZE) +
879 : 58 : lastFileSize;
880 : 58 : }
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 : 28 : BufFileAppend(BufFile *target, BufFile *source)
902 : : {
903 : 28 : int64 startBlock = (int64) target->numFiles * BUFFILE_SEG_SIZE;
904 : 28 : int newNumFiles = target->numFiles + source->numFiles;
905 : 28 : int i;
906 : :
907 [ + - ]: 28 : Assert(source->readOnly);
908 [ + - ]: 28 : Assert(!source->dirty);
909 : :
910 [ + - ]: 28 : if (target->resowner != source->resowner)
911 [ # # # # ]: 0 : elog(ERROR, "could not append BufFile with non-matching resource owner");
912 : :
913 : 28 : target->files = (File *)
914 : 28 : repalloc(target->files, sizeof(File) * newNumFiles);
915 [ + + ]: 56 : for (i = target->numFiles; i < newNumFiles; i++)
916 : 28 : target->files[i] = source->files[i - target->numFiles];
917 : 28 : target->numFiles = newNumFiles;
918 : :
919 : 56 : return startBlock;
920 : 28 : }
921 : :
922 : : /*
923 : : * Truncate a BufFile created by BufFileCreateFileSet up to the given fileno
924 : : * and the offset.
925 : : */
926 : : void
927 : 0 : BufFileTruncateFileSet(BufFile *file, int fileno, pgoff_t offset)
928 : : {
929 : 0 : int numFiles = file->numFiles;
930 : 0 : int newFile = fileno;
931 : 0 : pgoff_t newOffset = file->curOffset;
932 : 0 : char segment_name[MAXPGPATH];
933 : 0 : 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 [ # # ]: 0 : for (i = file->numFiles - 1; i >= fileno; i--)
942 : : {
943 [ # # # # ]: 0 : 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 : 0 : }
962 : : else
963 : : {
964 : 0 : if (FileTruncate(file->files[i], offset,
965 [ # # ]: 0 : 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 : 0 : newOffset = offset;
971 : : }
972 : 0 : }
973 : :
974 : 0 : 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 [ # # ]: 0 : if (newFile == file->curFile &&
981 [ # # # # ]: 0 : newOffset >= file->curOffset &&
982 : 0 : 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 : 0 : }
991 [ # # # # ]: 0 : else if (newFile == file->curFile &&
992 : 0 : 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 : 0 : }
1003 [ # # ]: 0 : 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 : 0 : }
1014 : : /* Nothing to do, if the truncate point is beyond current file. */
1015 : 0 : }
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