1 /* PSPP - computes sample statistics.
2 Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
3 Written by Ben Pfaff <blp@gnu.org>.
5 This program is free software; you can redistribute it and/or
6 modify it under the terms of the GNU General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 This program is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
30 #include <data/case-source.h>
31 #include <data/case.h>
32 #include <data/casefile.h>
33 #include <data/fastfile.h>
34 #include <data/procedure.h>
35 #include <data/settings.h>
36 #include <data/variable.h>
37 #include <data/storage-stream.h>
38 #include <language/expressions/public.h>
39 #include <libpspp/alloc.h>
40 #include <libpspp/array.h>
41 #include <libpspp/assertion.h>
42 #include <libpspp/message.h>
43 #include <libpspp/message.h>
44 #include <libpspp/misc.h>
45 #include <libpspp/str.h>
48 #define _(msgid) gettext (msgid)
50 /* These should only be changed for testing purposes. */
52 int max_buffers = INT_MAX;
53 bool allow_internal_sort = true;
55 static int compare_record (const struct ccase *, const struct ccase *,
56 const struct sort_criteria *);
57 static struct casefile *do_internal_sort (struct casereader *,
58 const struct sort_criteria *);
59 static struct casefile *do_external_sort (struct casereader *,
60 const struct sort_criteria *);
63 /* Sorts the active file in-place according to CRITERIA.
64 Returns true if successful. */
66 sort_active_file_in_place (struct dataset *ds,
67 const struct sort_criteria *criteria)
69 struct casefile *in, *out;
71 proc_cancel_temporary_transformations (ds);
72 if (!procedure (ds, NULL, NULL))
75 in = proc_capture_output (ds);
76 out = sort_execute (casefile_get_destructive_reader (in), criteria);
80 proc_set_source (ds, storage_source_create (out));
84 /* Data passed to sort_to_casefile_callback(). */
85 struct sort_to_casefile_cb_data
87 const struct sort_criteria *criteria;
88 struct casefile *output;
91 /* Sorts casefile CF according to the criteria in CB_DATA. */
93 sort_to_casefile_callback (const struct casefile *cf, void *cb_data_)
95 struct sort_to_casefile_cb_data *cb_data = cb_data_;
96 cb_data->output = sort_execute (casefile_get_reader (cf), cb_data->criteria);
97 return cb_data->output != NULL;
100 /* Sorts the active file to a separate casefile. If successful,
101 returns the sorted casefile. Returns a null pointer on
104 sort_active_file_to_casefile (struct dataset *ds,
105 const struct sort_criteria *criteria)
107 struct sort_to_casefile_cb_data cb_data;
109 proc_cancel_temporary_transformations (ds);
111 cb_data.criteria = criteria;
112 cb_data.output = NULL;
113 if (!multipass_procedure (ds, sort_to_casefile_callback, &cb_data))
115 casefile_destroy (cb_data.output);
118 return cb_data.output;
122 /* Reads all the cases from READER, which is destroyed. Sorts
123 the cases according to CRITERIA. Returns the sorted cases in
124 a newly created casefile. */
126 sort_execute (struct casereader *reader, const struct sort_criteria *criteria)
128 struct casefile *output = do_internal_sort (reader, criteria);
130 output = do_external_sort (reader, criteria);
131 casereader_destroy (reader);
135 /* A case and its index. */
138 struct ccase c; /* Case. */
139 unsigned long idx; /* Index to allow for stable sorting. */
142 static int compare_indexed_cases (const void *, const void *, const void *);
144 /* If the data is in memory, do an internal sort and return a new
145 casefile for the data. Otherwise, return a null pointer. */
146 static struct casefile *
147 do_internal_sort (struct casereader *reader,
148 const struct sort_criteria *criteria)
150 const struct casefile *src;
151 struct casefile *dst;
152 unsigned long case_cnt;
154 if (!allow_internal_sort)
157 src = casereader_get_casefile (reader);
158 if (casefile_get_case_cnt (src) > 1 && !casefile_in_core (src))
161 case_cnt = casefile_get_case_cnt (src);
162 dst = fastfile_create (casefile_get_value_cnt (src));
165 struct indexed_case *cases = nmalloc (sizeof *cases, case_cnt);
170 for (i = 0; i < case_cnt; i++)
172 bool ok = casereader_read_xfer (reader, &cases[i].c);
178 sort (cases, case_cnt, sizeof *cases, compare_indexed_cases,
181 for (i = 0; i < case_cnt; i++)
182 casefile_append_xfer (dst, &cases[i].c);
183 if (casefile_error (dst))
191 casefile_destroy (dst);
199 /* Compares the variables specified by CRITERIA between the cases
200 at A and B, with a "last resort" comparison for stability, and
201 returns a strcmp()-type result. */
203 compare_indexed_cases (const void *a_, const void *b_, const void *criteria_)
205 const struct sort_criteria *criteria = criteria_;
206 const struct indexed_case *a = a_;
207 const struct indexed_case *b = b_;
208 int result = compare_record (&a->c, &b->c, criteria);
210 result = a->idx < b->idx ? -1 : a->idx > b->idx;
216 /* Maximum order of merge (external sort only). The maximum
217 reasonable value is about 7. Above that, it would be a good
218 idea to use a heap in merge_once() to select the minimum. */
219 #define MAX_MERGE_ORDER 7
221 /* Results of an external sort. */
224 const struct sort_criteria *criteria; /* Sort criteria. */
225 size_t value_cnt; /* Size of data in `union value's. */
226 struct casefile **runs; /* Array of initial runs. */
227 size_t run_cnt, run_cap; /* Number of runs, allocated capacity. */
230 /* Prototypes for helper functions. */
231 static int write_runs (struct external_sort *, struct casereader *);
232 static struct casefile *merge (struct external_sort *);
233 static void destroy_external_sort (struct external_sort *);
235 /* Performs a stable external sort of the active file according
236 to the specification in SCP. Forms initial runs using a heap
237 as a reservoir. Merges the initial runs according to a
238 pattern that assures stability. */
239 static struct casefile *
240 do_external_sort (struct casereader *reader,
241 const struct sort_criteria *criteria)
243 struct external_sort *xsrt;
245 if (!casefile_to_disk (casereader_get_casefile (reader)))
248 xsrt = xmalloc (sizeof *xsrt);
249 xsrt->criteria = criteria;
250 xsrt->value_cnt = casefile_get_value_cnt (casereader_get_casefile (reader));
253 xsrt->runs = xnmalloc (xsrt->run_cap, sizeof *xsrt->runs);
254 if (write_runs (xsrt, reader))
256 struct casefile *output = merge (xsrt);
257 destroy_external_sort (xsrt);
262 destroy_external_sort (xsrt);
269 destroy_external_sort (struct external_sort *xsrt)
275 for (i = 0; i < xsrt->run_cnt; i++)
276 casefile_destroy (xsrt->runs[i]);
282 /* Replacement selection. */
284 /* Pairs a record with a run number. */
287 int run; /* Run number of case. */
288 struct ccase record; /* Case data. */
289 size_t idx; /* Case number (for stability). */
292 /* Represents a set of initial runs during an external sort. */
293 struct initial_run_state
295 struct external_sort *xsrt;
298 struct record_run *records; /* Records arranged as a heap. */
299 size_t record_cnt; /* Current number of records. */
300 size_t record_cap; /* Capacity for records. */
302 /* Run currently being output. */
303 int run; /* Run number. */
304 size_t case_cnt; /* Number of cases so far. */
305 struct casefile *casefile; /* Output file. */
306 struct ccase last_output; /* Record last output. */
308 int okay; /* Zero if an error has been encountered. */
311 static bool destroy_initial_run_state (struct initial_run_state *);
312 static void process_case (struct initial_run_state *,
313 const struct ccase *, size_t);
314 static int allocate_cases (struct initial_run_state *);
315 static void output_record (struct initial_run_state *);
316 static void start_run (struct initial_run_state *);
317 static void end_run (struct initial_run_state *);
318 static int compare_record_run (const struct record_run *,
319 const struct record_run *,
320 const struct initial_run_state *);
321 static int compare_record_run_minheap (const void *, const void *,
324 /* Reads cases from READER and composes initial runs in XSRT. */
326 write_runs (struct external_sort *xsrt, struct casereader *reader)
328 struct initial_run_state *irs;
333 /* Allocate memory for cases. */
334 irs = xmalloc (sizeof *irs);
337 irs->record_cnt = irs->record_cap = 0;
340 irs->casefile = NULL;
341 case_nullify (&irs->last_output);
343 if (!allocate_cases (irs))
346 /* Create initial runs. */
348 for (; irs->okay && casereader_read (reader, &c); case_destroy (&c))
349 process_case (irs, &c, idx++);
350 while (irs->okay && irs->record_cnt > 0)
357 if (!destroy_initial_run_state (irs))
363 /* Add a single case to an initial run. */
365 process_case (struct initial_run_state *irs, const struct ccase *c,
368 struct record_run *rr;
370 /* Compose record_run for this run and add to heap. */
371 assert (irs->record_cnt < irs->record_cap - 1);
372 rr = irs->records + irs->record_cnt++;
373 case_copy (&rr->record, 0, c, 0, irs->xsrt->value_cnt);
376 if (!case_is_null (&irs->last_output)
377 && compare_record (c, &irs->last_output, irs->xsrt->criteria) < 0)
378 rr->run = irs->run + 1;
379 push_heap (irs->records, irs->record_cnt, sizeof *irs->records,
380 compare_record_run_minheap, irs);
382 /* Output a record if the reservoir is full. */
383 if (irs->record_cnt == irs->record_cap - 1 && irs->okay)
387 /* Destroys the initial run state represented by IRS.
388 Returns true if successful, false if an I/O error occurred. */
390 destroy_initial_run_state (struct initial_run_state *irs)
398 for (i = 0; i < irs->record_cap; i++)
399 case_destroy (&irs->records[i].record);
402 if (irs->casefile != NULL)
403 ok = casefile_sleep (irs->casefile);
409 /* Allocates room for lots of cases as a buffer. */
411 allocate_cases (struct initial_run_state *irs)
413 int approx_case_cost; /* Approximate memory cost of one case in bytes. */
414 int max_cases; /* Maximum number of cases to allocate. */
417 /* Allocate as many cases as we can within the workspace
419 approx_case_cost = (sizeof *irs->records
420 + irs->xsrt->value_cnt * sizeof (union value)
421 + 4 * sizeof (void *));
422 max_cases = get_workspace() / approx_case_cost;
423 if (max_cases > max_buffers)
424 max_cases = max_buffers;
425 irs->records = nmalloc (sizeof *irs->records, max_cases);
426 if (irs->records != NULL)
427 for (i = 0; i < max_cases; i++)
428 if (!case_try_create (&irs->records[i].record, irs->xsrt->value_cnt))
433 irs->record_cap = max_cases;
435 /* Fail if we didn't allocate an acceptable number of cases. */
436 if (irs->records == NULL || max_cases < min_buffers)
438 msg (SE, _("Out of memory. Could not allocate room for minimum of %d "
439 "cases of %d bytes each. (PSPP workspace is currently "
440 "restricted to a maximum of %d KB.)"),
441 min_buffers, approx_case_cost, get_workspace() / 1024);
447 /* Compares the VAR_CNT variables in VARS[] between the `value's at
448 A and B, and returns a strcmp()-type result. */
450 compare_record (const struct ccase *a, const struct ccase *b,
451 const struct sort_criteria *criteria)
458 for (i = 0; i < criteria->crit_cnt; i++)
460 const struct sort_criterion *c = &criteria->crits[i];
465 double af = case_num (a, c->fv);
466 double bf = case_num (b, c->fv);
468 result = af < bf ? -1 : af > bf;
471 result = memcmp (case_str (a, c->fv), case_str (b, c->fv), c->width);
474 return c->dir == SRT_ASCEND ? result : -result;
480 /* Compares record-run tuples A and B on run number first, then
481 on record, then on case index. */
483 compare_record_run (const struct record_run *a,
484 const struct record_run *b,
485 const struct initial_run_state *irs)
487 int result = a->run < b->run ? -1 : a->run > b->run;
489 result = compare_record (&a->record, &b->record, irs->xsrt->criteria);
491 result = a->idx < b->idx ? -1 : a->idx > b->idx;
495 /* Compares record-run tuples A and B on run number first, then
496 on the current record according to SCP, but in descending
499 compare_record_run_minheap (const void *a, const void *b, const void *irs)
501 return -compare_record_run (a, b, irs);
504 /* Begins a new initial run, specifically its output file. */
506 start_run (struct initial_run_state *irs)
510 irs->casefile = fastfile_create (irs->xsrt->value_cnt);
511 casefile_to_disk (irs->casefile);
512 case_nullify (&irs->last_output);
515 /* Ends the current initial run. */
517 end_run (struct initial_run_state *irs)
519 struct external_sort *xsrt = irs->xsrt;
521 /* Record initial run. */
522 if (irs->casefile != NULL)
524 casefile_sleep (irs->casefile);
525 if (xsrt->run_cnt >= xsrt->run_cap)
528 xsrt->runs = xnrealloc (xsrt->runs,
529 xsrt->run_cap, sizeof *xsrt->runs);
531 xsrt->runs[xsrt->run_cnt++] = irs->casefile;
532 if (casefile_error (irs->casefile))
534 irs->casefile = NULL;
538 /* Writes a record to the current initial run. */
540 output_record (struct initial_run_state *irs)
542 struct record_run *record_run;
543 struct ccase case_tmp;
545 /* Extract minimum case from heap. */
546 assert (irs->record_cnt > 0);
547 pop_heap (irs->records, irs->record_cnt--, sizeof *irs->records,
548 compare_record_run_minheap, irs);
549 record_run = irs->records + irs->record_cnt;
551 /* Bail if an error has occurred. */
555 /* Start new run if necessary. */
556 assert (record_run->run == irs->run
557 || record_run->run == irs->run + 1);
558 if (record_run->run != irs->run)
563 assert (record_run->run == irs->run);
567 if (irs->casefile != NULL)
568 casefile_append (irs->casefile, &record_run->record);
570 /* This record becomes last_output. */
571 irs->last_output = case_tmp = record_run->record;
572 record_run->record = irs->records[irs->record_cap - 1].record;
573 irs->records[irs->record_cap - 1].record = case_tmp;
578 static int choose_merge (struct casefile *runs[], int run_cnt, int order);
579 static struct casefile *merge_once (struct external_sort *,
580 struct casefile *[], size_t);
582 /* Repeatedly merges run until only one is left,
583 and returns the final casefile.
584 Returns a null pointer if an I/O error occurs. */
585 static struct casefile *
586 merge (struct external_sort *xsrt)
588 while (xsrt->run_cnt > 1)
590 int order = min (MAX_MERGE_ORDER, xsrt->run_cnt);
591 int idx = choose_merge (xsrt->runs, xsrt->run_cnt, order);
592 xsrt->runs[idx] = merge_once (xsrt, xsrt->runs + idx, order);
593 remove_range (xsrt->runs, xsrt->run_cnt, sizeof *xsrt->runs,
595 xsrt->run_cnt -= order - 1;
597 if (xsrt->runs[idx] == NULL)
600 assert (xsrt->run_cnt == 1);
602 return xsrt->runs[0];
605 /* Chooses ORDER runs out of the RUN_CNT runs in RUNS to merge,
606 and returns the index of the first one.
608 For stability, we must merge only consecutive runs. For
609 efficiency, we choose the shortest consecutive sequence of
612 choose_merge (struct casefile *runs[], int run_cnt, int order)
614 int min_idx, min_sum;
615 int cur_idx, cur_sum;
618 /* Sum up the length of the first ORDER runs. */
620 for (i = 0; i < order; i++)
621 cur_sum += casefile_get_case_cnt (runs[i]);
623 /* Find the shortest group of ORDER runs,
624 using a running total for efficiency. */
627 for (cur_idx = 1; cur_idx + order <= run_cnt; cur_idx++)
629 cur_sum -= casefile_get_case_cnt (runs[cur_idx - 1]);
630 cur_sum += casefile_get_case_cnt (runs[cur_idx + order - 1]);
631 if (cur_sum < min_sum)
641 /* Merges the RUN_CNT initial runs specified in INPUT_FILES into a
642 new run, and returns the new run.
643 Returns a null pointer if an I/O error occurs. */
644 static struct casefile *
645 merge_once (struct external_sort *xsrt,
646 struct casefile **const input_files,
651 struct casefile *file;
652 struct casereader *reader;
657 struct casefile *output = NULL;
660 /* Open input files. */
661 runs = xnmalloc (run_cnt, sizeof *runs);
662 for (i = 0; i < run_cnt; i++)
664 struct run *r = &runs[i];
665 r->file = input_files[i];
666 r->reader = casefile_get_destructive_reader (r->file);
667 if (!casereader_read_xfer (r->reader, &r->ccase))
674 /* Create output file. */
675 output = fastfile_create (xsrt->value_cnt);
676 casefile_to_disk (output);
681 struct run *min_run, *run;
685 for (run = runs + 1; run < runs + run_cnt; run++)
686 if (compare_record (&run->ccase, &min_run->ccase, xsrt->criteria) < 0)
689 /* Write minimum to output file. */
690 casefile_append_xfer (output, &min_run->ccase);
692 /* Read another case from minimum run. */
693 if (!casereader_read_xfer (min_run->reader, &min_run->ccase))
695 if (casefile_error (min_run->file) || casefile_error (output))
697 casereader_destroy (min_run->reader);
698 casefile_destroy (min_run->file);
700 remove_element (runs, run_cnt, sizeof *runs, min_run - runs);
705 if (!casefile_sleep (output))
712 for (i = 0; i < run_cnt; i++)
713 casefile_destroy (runs[i].file);
714 casefile_destroy (output);