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
  63   /* Get exclusive write access to handle. */
  64   /* TRANSLATORS: this fragment will be interpolated into
  65      messages in fh_lock() that identify types of files. */
  66   lock = fh_lock (fh, FH_REF_SCRATCH, N_("scratch file"), FH_ACC_WRITE, true);
  67   if (lock == NULL)
  68     return NULL;
  69
  70   /* Create writer. */
  71   writer = xmalloc (sizeof *writer);
  72   writer->lock = lock;
  73   writer->fh = fh_ref (fh);
  74
  75   writer->dict = dict_clone (dictionary);
  76   dict_delete_scratch_vars (writer->dict);
  77   if (dict_count_values (writer->dict, 0)
  78       < dict_get_next_value_idx (writer->dict))
  79     {
  80       writer->compactor = case_map_to_compact_dict (writer->dict, 0);
  81       dict_compact_values (writer->dict);
  82     }
  83   else
  84     writer->compactor = NULL;
  85   writer->subwriter = autopaging_writer_create (dict_get_proto (writer->dict));
  86
  87   casewriter = casewriter_create (dict_get_proto (writer->dict),
  88                                   &scratch_writer_casewriter_class, writer);
  89   taint_propagate (casewriter_get_taint (writer->subwriter),
  90                    casewriter_get_taint (casewriter));
  91   return casewriter;
  92 }
  93
  94 /* Writes case C to WRITER. */
  95 static void
  96 scratch_writer_casewriter_write (struct casewriter *w UNUSED, void *writer_,
  97                                  struct ccase *c)
  98 {
  99   struct scratch_writer *writer = writer_;
 100   casewriter_write (writer->subwriter,
 101                     case_map_execute (writer->compactor, c));
 102 }
 103
 104 /* Closes WRITER. */
 105 static void
 106 scratch_writer_casewriter_destroy (struct casewriter *w UNUSED, void *writer_)
 107 {
 108   static unsigned int next_unique_id = 0x12345678;
 109
 110   struct scratch_writer *writer = writer_;
 111   struct casereader *reader = casewriter_make_reader (writer->subwriter);
 112   if (!casereader_error (reader))
 113     {
 114       /* Destroy previous contents of handle. */
 115       struct scratch_handle *sh = fh_get_scratch_handle (writer->fh);
 116       if (sh != NULL)
 117         scratch_handle_destroy (sh);
 118
 119       /* Create new contents. */
 120       sh = xmalloc (sizeof *sh);
 121       sh->unique_id = ++next_unique_id;
 122       sh->dictionary = writer->dict;
 123       sh->casereader = reader;
 124       fh_set_scratch_handle (writer->fh, sh);
 125     }
 126   else
 127     {
 128       casereader_destroy (reader);
 129       dict_destroy (writer->dict);
 130     }
 131
 132   fh_unlock (writer->lock);
 133   fh_unref (writer->fh);
 134   free (writer);
 135 }
 136
 137 static const struct casewriter_class scratch_writer_casewriter_class =
 138   {
 139     scratch_writer_casewriter_write,
 140     scratch_writer_casewriter_destroy,
 141     NULL,
 142   };