src/data/scratch-writer.c

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 2006, 2009 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 #include <config.h>
  18
  19 #include "scratch-writer.h"
  20
  21 #include <stdlib.h>
  22
  23 #include <data/case.h>
  24 #include <data/case-map.h>
  25 #include <data/casereader.h>
  26 #include <data/casewriter-provider.h>
  27 #include <data/casewriter.h>
  28 #include <data/dictionary.h>
  29 #include <data/file-handle-def.h>
  30 #include <data/scratch-handle.h>
  31 #include <data/variable.h>
  32 #include <libpspp/compiler.h>
  33 #include <libpspp/taint.h>
  34
  35 #include "xalloc.h"
  36
  37 #define N_(msgid) (msgid)
  38
  39 /* A scratch file writer. */
  40 struct scratch_writer
  41   {
  42     struct file_handle *fh;             /* Underlying file handle. */
  43     struct fh_lock *lock;               /* Exclusive access to file handle. */
  44     struct dictionary *dict;            /* Dictionary for subwriter. */
  45     struct case_map *compactor;         /* Compacts into dictionary. */
  46     struct casewriter *subwriter;       /* Data output. */
  47   };
  48
  49 static const struct casewriter_class scratch_writer_casewriter_class;
  50
  51 /* Opens FH, which must have referent type FH_REF_SCRATCH, and
  52    returns a scratch_writer for it, or a null pointer on
  53    failure.  Cases stored in the scratch_writer will be expected
  54    to be drawn from DICTIONARY. */
  55 struct casewriter *
  56 scratch_writer_open (struct file_handle *fh,
  57                      const struct dictionary *dictionary)
  58 {
  59   struct scratch_writer *writer;
  60   struct casewriter *casewriter;
  61   struct fh_lock *lock;
  62   size_t dict_value_cnt;
  63
  64   /* Get exclusive write access to handle. */
  65   /* TRANSLATORS: this fragment will be interpolated into
  66      messages in fh_lock() that identify types of files. */
  67   lock = fh_lock (fh, FH_REF_SCRATCH, N_("scratch file"), FH_ACC_WRITE, true);
  68   if (lock == NULL)
  69     return NULL;
  70
  71   /* Create writer. */
  72   writer = xmalloc (sizeof *writer);
  73   writer->lock = lock;
  74   writer->fh = fh_ref (fh);
  75
  76   writer->dict = dict_clone (dictionary);
  77   dict_delete_scratch_vars (writer->dict);
  78   if (dict_count_values (writer->dict, 0)
  79       < dict_get_next_value_idx (writer->dict))
  80     {
  81       writer->compactor = case_map_to_compact_dict (writer->dict, 0);
  82       dict_compact_values (writer->dict);
  83     }
  84   else
  85     writer->compactor = NULL;
  86   dict_value_cnt = dict_get_next_value_idx (writer->dict);
  87   writer->subwriter = autopaging_writer_create (dict_value_cnt);
  88
  89   casewriter = casewriter_create (dict_value_cnt,
  90                                   &scratch_writer_casewriter_class, writer);
  91   taint_propagate (casewriter_get_taint (writer->subwriter),
  92                    casewriter_get_taint (casewriter));
  93   return casewriter;
  94 }
  95
  96 /* Writes case C to WRITER. */
  97 static void
  98 scratch_writer_casewriter_write (struct casewriter *w UNUSED, void *writer_,
  99                                  struct ccase *c)
 100 {
 101   struct scratch_writer *writer = writer_;
 102   casewriter_write (writer->subwriter,
 103                     case_map_execute (writer->compactor, c));
 104 }
 105
 106 /* Closes WRITER. */
 107 static void
 108 scratch_writer_casewriter_destroy (struct casewriter *w UNUSED, void *writer_)
 109 {
 110   static unsigned int next_unique_id = 0x12345678;
 111
 112   struct scratch_writer *writer = writer_;
 113   struct casereader *reader = casewriter_make_reader (writer->subwriter);
 114   if (!casereader_error (reader))
 115     {
 116       /* Destroy previous contents of handle. */
 117       struct scratch_handle *sh = fh_get_scratch_handle (writer->fh);
 118       if (sh != NULL)
 119         scratch_handle_destroy (sh);
 120
 121       /* Create new contents. */
 122       sh = xmalloc (sizeof *sh);
 123       sh->unique_id = ++next_unique_id;
 124       sh->dictionary = writer->dict;
 125       sh->casereader = reader;
 126       fh_set_scratch_handle (writer->fh, sh);
 127     }
 128   else
 129     {
 130       casereader_destroy (reader);
 131       dict_destroy (writer->dict);
 132     }
 133
 134   fh_unlock (writer->lock);
 135   fh_unref (writer->fh);
 136   free (writer);
 137 }
 138
 139 static const struct casewriter_class scratch_writer_casewriter_class =
 140   {
 141     scratch_writer_casewriter_write,
 142     scratch_writer_casewriter_destroy,
 143     NULL,
 144   };