src/data/casewindow.c

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 2007, 2009, 2011 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
  16
  17 /* This casewindow implementation in terms of an class interface
  18    is undoubtedly a form of over-abstraction.  However, it works
  19    and the extra abstraction seems to be harmless. */
  20
  21 #include <config.h>
  22
  23 #include "data/casewindow.h"
  24
  25 #include <stdlib.h>
  26
  27 #include "data/case-tmpfile.h"
  28 #include "libpspp/assertion.h"
  29 #include "libpspp/compiler.h"
  30 #include "libpspp/deque.h"
  31 #include "libpspp/taint.h"
  32
  33 #include "gl/xalloc.h"
  34
  35 /* A queue of cases. */
  36 struct casewindow
  37   {
  38     /* Common data. */
  39     struct caseproto *proto;      /* Prototype of cases in window. */
  40     casenumber max_in_core_cases; /* Max cases before dumping to disk. */
  41     struct taint *taint;          /* Taint status. */
  42
  43     /* Implementation data. */
  44     const struct casewindow_class *class;
  45     void *aux;
  46   };
  47
  48 /* Implementation of a casewindow. */
  49 struct casewindow_class
  50   {
  51     void *(*create) (struct taint *, const struct caseproto *);
  52     void (*destroy) (void *aux);
  53     void (*push_head) (void *aux, struct ccase *);
  54     void (*pop_tail) (void *aux, casenumber n);
  55     struct ccase *(*get_case) (void *aux, casenumber ofs);
  56     casenumber (*get_n_cases) (const void *aux);
  57   };
  58
  59 /* Classes. */
  60 static const struct casewindow_class casewindow_memory_class;
  61 static const struct casewindow_class casewindow_file_class;
  62
  63 /* Creates and returns a new casewindow using the given
  64    parameters. */
  65 static struct casewindow *
  66 do_casewindow_create (struct taint *taint, const struct caseproto *proto,
  67                       casenumber max_in_core_cases)
  68 {
  69   struct casewindow *cw = xmalloc (sizeof *cw);
  70   cw->class = (max_in_core_cases
  71               ? &casewindow_memory_class
  72               : &casewindow_file_class);
  73   cw->aux = cw->class->create (taint, proto);
  74   cw->proto = caseproto_ref (proto);
  75   cw->max_in_core_cases = max_in_core_cases;
  76   cw->taint = taint;
  77   return cw;
  78 }
  79
  80 /* Creates and returns a new casewindow for cases that take the
  81    form specified by PROTO.  If the casewindow holds more than
  82    MAX_IN_CORE_CASES cases at any time, its cases will be dumped
  83    to disk; otherwise, its cases will be held in memory.
  84
  85    The caller retains its reference to PROTO. */
  86 struct casewindow *
  87 casewindow_create (const struct caseproto *proto, casenumber max_in_core_cases)
  88 {
  89   return do_casewindow_create (taint_create (), proto, max_in_core_cases);
  90 }
  91
  92 /* Destroys casewindow CW.
  93    Returns true if CW was tainted, which is caused by an I/O
  94    error or by taint propagation to the casewindow. */
  95 bool
  96 casewindow_destroy (struct casewindow *cw)
  97 {
  98   bool ok = true;
  99   if (cw != NULL)
 100     {
 101       cw->class->destroy (cw->aux);
 102       ok = taint_destroy (cw->taint);
 103       caseproto_unref (cw->proto);
 104       free (cw);
 105     }
 106   return ok;
 107 }
 108
 109 /* Swaps the contents of casewindows A and B. */
 110 static void
 111 casewindow_swap (struct casewindow *a, struct casewindow *b)
 112 {
 113   struct casewindow tmp = *a;
 114   *a = *b;
 115   *b = tmp;
 116 }
 117
 118 /* Dumps the contents of casewindow OLD to disk. */
 119 static void
 120 casewindow_to_disk (struct casewindow *old)
 121 {
 122   struct casewindow *new;
 123   new = do_casewindow_create (taint_clone (old->taint), old->proto, 0);
 124   while (casewindow_get_n_cases (old) > 0 && !casewindow_error (new))
 125     {
 126       struct ccase *c = casewindow_get_case (old, 0);
 127       if (c == NULL)
 128         break;
 129       casewindow_pop_tail (old, 1);
 130       casewindow_push_head (new, c);
 131     }
 132   casewindow_swap (old, new);
 133   casewindow_destroy (new);
 134 }
 135
 136 /* Pushes case C at the head of casewindow CW.
 137    Case C becomes owned by the casewindow. */
 138 void
 139 casewindow_push_head (struct casewindow *cw, struct ccase *c)
 140 {
 141   if (!casewindow_error (cw))
 142     {
 143       cw->class->push_head (cw->aux, c);
 144       if (!casewindow_error (cw))
 145         {
 146           casenumber n_cases = cw->class->get_n_cases (cw->aux);
 147           if (n_cases > cw->max_in_core_cases
 148               && cw->class == &casewindow_memory_class)
 149             casewindow_to_disk (cw);
 150         }
 151     }
 152   else
 153     case_unref (c);
 154 }
 155
 156 /* Deletes N_CASES cases at the tail of casewindow CW. */
 157 void
 158 casewindow_pop_tail (struct casewindow *cw, casenumber n_cases)
 159 {
 160   if (!casewindow_error (cw))
 161     cw->class->pop_tail (cw->aux, n_cases);
 162 }
 163
 164 /* Returns the case that is CASE_IDX cases away from CW's tail
 165    into C, or a null pointer on an I/O error or if CW is
 166    otherwise tainted.  The caller must call case_unref() on the
 167    returned case when it is no longer needed. */
 168 struct ccase *
 169 casewindow_get_case (const struct casewindow *cw_, casenumber case_idx)
 170 {
 171   struct casewindow *cw = CONST_CAST (struct casewindow *, cw_);
 172
 173   assert (case_idx >= 0 && case_idx < casewindow_get_n_cases (cw));
 174   if (casewindow_error (cw))
 175     return NULL;
 176   return cw->class->get_case (cw->aux, case_idx);
 177 }
 178
 179 /* Returns the number of cases in casewindow CW. */
 180 casenumber
 181 casewindow_get_n_cases (const struct casewindow *cw)
 182 {
 183   return cw->class->get_n_cases (cw->aux);
 184 }
 185
 186 /* Returns the case prototype for the cases in casewindow CW.
 187    The caller must not unref the returned prototype. */
 188 const struct caseproto *
 189 casewindow_get_proto (const struct casewindow *cw)
 190 {
 191   return cw->proto;
 192 }
 193
 194 /* Returns true if casewindow CW is tainted.
 195    A casewindow is tainted by an I/O error or by taint
 196    propagation to the casewindow. */
 197 bool
 198 casewindow_error (const struct casewindow *cw)
 199 {
 200   return taint_is_tainted (cw->taint);
 201 }
 202
 203 /* Marks casewindow CW tainted. */
 204 void
 205 casewindow_force_error (struct casewindow *cw)
 206 {
 207   taint_set_taint (cw->taint);
 208 }
 209
 210 /* Returns casewindow CW's taint object. */
 211 const struct taint *
 212 casewindow_get_taint (const struct casewindow *cw)
 213 {
 214   return cw->taint;
 215 }
 216 \f
 217 /* In-memory casewindow data. */
 218 struct casewindow_memory
 219   {
 220     struct deque deque;
 221     struct ccase **cases;
 222   };
 223
 224 static void *
 225 casewindow_memory_create (struct taint *taint UNUSED,
 226                           const struct caseproto *proto UNUSED)
 227 {
 228   struct casewindow_memory *cwm = xmalloc (sizeof *cwm);
 229   *cwm = (struct casewindow_memory) { .deque = DEQUE_EMPTY_INITIALIZER };
 230   return cwm;
 231 }
 232
 233 static void
 234 casewindow_memory_destroy (void *cwm_)
 235 {
 236   struct casewindow_memory *cwm = cwm_;
 237   while (!deque_is_empty (&cwm->deque))
 238     case_unref (cwm->cases[deque_pop_front (&cwm->deque)]);
 239   free (cwm->cases);
 240   free (cwm);
 241 }
 242
 243 static void
 244 casewindow_memory_push_head (void *cwm_, struct ccase *c)
 245 {
 246   struct casewindow_memory *cwm = cwm_;
 247   if (deque_is_full (&cwm->deque))
 248     cwm->cases = deque_expand (&cwm->deque, cwm->cases, sizeof *cwm->cases);
 249   cwm->cases[deque_push_back (&cwm->deque)] = c;
 250 }
 251
 252 static void
 253 casewindow_memory_pop_tail (void *cwm_, casenumber n_cases)
 254 {
 255   struct casewindow_memory *cwm = cwm_;
 256   assert (deque_count (&cwm->deque) >= n_cases);
 257   while (n_cases-- > 0)
 258     case_unref (cwm->cases[deque_pop_front (&cwm->deque)]);
 259 }
 260
 261 static struct ccase *
 262 casewindow_memory_get_case (void *cwm_, casenumber ofs)
 263 {
 264   struct casewindow_memory *cwm = cwm_;
 265   return case_ref (cwm->cases[deque_front (&cwm->deque, ofs)]);
 266 }
 267
 268 static casenumber
 269 casewindow_memory_get_n_cases (const void *cwm_)
 270 {
 271   const struct casewindow_memory *cwm = cwm_;
 272   return deque_count (&cwm->deque);
 273 }
 274
 275 static const struct casewindow_class casewindow_memory_class =
 276   {
 277     casewindow_memory_create,
 278     casewindow_memory_destroy,
 279     casewindow_memory_push_head,
 280     casewindow_memory_pop_tail,
 281     casewindow_memory_get_case,
 282     casewindow_memory_get_n_cases,
 283   };
 284 \f
 285 /* On-disk casewindow data. */
 286 struct casewindow_file
 287   {
 288     struct case_tmpfile *file;
 289     casenumber head, tail;
 290   };
 291
 292 static void *
 293 casewindow_file_create (struct taint *taint, const struct caseproto *proto)
 294 {
 295   struct casewindow_file *cwf = xmalloc (sizeof *cwf);
 296   cwf->file = case_tmpfile_create (proto);
 297   cwf->head = cwf->tail = 0;
 298   taint_propagate (case_tmpfile_get_taint (cwf->file), taint);
 299   return cwf;
 300 }
 301
 302 static void
 303 casewindow_file_destroy (void *cwf_)
 304 {
 305   struct casewindow_file *cwf = cwf_;
 306   case_tmpfile_destroy (cwf->file);
 307   free (cwf);
 308 }
 309
 310 static void
 311 casewindow_file_push_head (void *cwf_, struct ccase *c)
 312 {
 313   struct casewindow_file *cwf = cwf_;
 314   if (case_tmpfile_put_case (cwf->file, cwf->head, c))
 315     cwf->head++;
 316 }
 317
 318 static void
 319 casewindow_file_pop_tail (void *cwf_, casenumber n)
 320 {
 321   struct casewindow_file *cwf = cwf_;
 322   assert (n <= cwf->head - cwf->tail);
 323   cwf->tail += n;
 324   if (cwf->head == cwf->tail)
 325     cwf->head = cwf->tail = 0;
 326 }
 327
 328 static struct ccase *
 329 casewindow_file_get_case (void *cwf_, casenumber ofs)
 330 {
 331   struct casewindow_file *cwf = cwf_;
 332   return case_tmpfile_get_case (cwf->file, cwf->tail + ofs);
 333 }
 334
 335 static casenumber
 336 casewindow_file_get_n_cases (const void *cwf_)
 337 {
 338   const struct casewindow_file *cwf = cwf_;
 339   return cwf->head - cwf->tail;
 340 }
 341
 342 static const struct casewindow_class casewindow_file_class =
 343   {
 344     casewindow_file_create,
 345     casewindow_file_destroy,
 346     casewindow_file_push_head,
 347     casewindow_file_pop_tail,
 348     casewindow_file_get_case,
 349     casewindow_file_get_n_cases,
 350   };