git.ozlabs.org Git - ccan/blob - ccan/tdb/summary.c

   1  /*
   2    Trivial Database: human-readable summary code
   3    Copyright (C) Rusty Russell 2010
   4
   5    This library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 3 of the License, or (at your option) any later version.
   9
  10    This library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17 */
  18 #include "tdb_private.h"
  19 #include <ccan/tally/tally.h>
  20
  21 #define SUMMARY_FORMAT \
  22         "Size of file: %zu\n" \
  23         "Number of records: %zu\n" \
  24         "Smallest/average/largest records: %zu/%zu/%zu\n%s" \
  25         "Smallest/average/largest padding: %zu/%zu/%zu\n%s" \
  26         "Number of dead records: %zu\n" \
  27         "Smallest/average/largest dead records: %zu/%zu/%zu\n%s" \
  28         "Number of free records: %zu\n" \
  29         "Smallest/average/largest free records: %zu/%zu/%zu\n%s" \
  30         "Number of hash chains: %zu\n" \
  31         "Smallest/average/largest hash chains: %zu/%zu/%zu\n%s" \
  32         "Total data = %zu (%.0f%%)\n"
  33
  34 #define HISTO_WIDTH 70
  35 #define HISTO_HEIGHT 20
  36
  37 /* Slow, but should be very rare. */
  38 static size_t dead_space(struct tdb_context *tdb, tdb_off_t off)
  39 {
  40         size_t len;
  41
  42         for (len = 0; off + len < tdb->map_size; len++) {
  43                 char c;
  44                 if (tdb->methods->tdb_read(tdb, off, &c, 1, 0))
  45                         return 0;
  46                 if (c != 0 && c != 0x42)
  47                         break;
  48         }
  49         return len;
  50 }
  51
  52 static size_t get_hash_length(struct tdb_context *tdb, unsigned int i)
  53 {
  54         tdb_off_t rec_ptr;
  55         size_t count = 0;
  56
  57         if (tdb_ofs_read(tdb, TDB_HASH_TOP(i), &rec_ptr) == -1)
  58                 return 0;
  59
  60         /* keep looking until we find the right record */
  61         while (rec_ptr) {
  62                 struct tdb_record r;
  63                 ++count;
  64                 if (tdb_rec_read(tdb, rec_ptr, &r) == -1)
  65                         return 0;
  66                 rec_ptr = r.next;
  67         }
  68         return count;
  69 }
  70
  71 char *tdb_summary(struct tdb_context *tdb, enum tdb_summary_flags flags)
  72 {
  73         tdb_off_t off;
  74         struct tally *freet, *used, *dead, *extra, *hash;
  75         char *freeg, *usedg, *deadg, *extrag, *hashg;
  76         struct tdb_record rec;
  77         char *ret = NULL;
  78         bool locked;
  79         size_t len;
  80
  81         /* Read-only databases use no locking at all: it's best-effort.
  82          * We may have a write lock already, so skip that case too. */
  83         if (tdb->read_only || tdb->allrecord_lock.count != 0) {
  84                 locked = false;
  85         } else {
  86                 if (tdb_lockall_read(tdb) == -1)
  87                         return NULL;
  88                 locked = true;
  89         }
  90
  91         freet = tally_new(HISTO_HEIGHT);
  92         used = tally_new(HISTO_HEIGHT);
  93         dead = tally_new(HISTO_HEIGHT);
  94         extra = tally_new(HISTO_HEIGHT);
  95         hash = tally_new(HISTO_HEIGHT);
  96         if (!freet || !used || !dead || !extra || !hash) {
  97                 tdb->ecode = TDB_ERR_OOM;
  98                 goto unlock;
  99         }
 100
 101         for (off = TDB_DATA_START(tdb->header.hash_size);
 102              off < tdb->map_size - 1;
 103              off += sizeof(rec) + rec.rec_len) {
 104                 if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec),
 105                                            DOCONV()) == -1)
 106                         goto unlock;
 107                 switch (rec.magic) {
 108                 case TDB_MAGIC:
 109                         tally_add(used, rec.key_len + rec.data_len);
 110                         tally_add(extra, rec.rec_len - (rec.key_len
 111                                                         + rec.data_len));
 112                         break;
 113                 case TDB_FREE_MAGIC:
 114                         tally_add(freet, sizeof(rec) + rec.rec_len);
 115                         break;
 116                 /* If we crash after ftruncate, we can get zeroes or fill. */
 117                 case TDB_RECOVERY_INVALID_MAGIC:
 118                 case 0x42424242:
 119                         rec.rec_len = dead_space(tdb, off) - sizeof(rec);
 120                         /* Fall through */
 121                 case TDB_DEAD_MAGIC:
 122                         tally_add(dead, sizeof(rec) + rec.rec_len);
 123                         break;
 124                 default:
 125                         TDB_LOG((tdb, TDB_DEBUG_ERROR,
 126                                  "Unexpected record magic 0x%x at offset %d\n",
 127                                  rec.magic, off));
 128                         goto unlock;
 129                 }
 130         }
 131
 132         for (off = 0; off < tdb->header.hash_size; off++)
 133                 tally_add(hash, get_hash_length(tdb, off));
 134
 135         if (flags & TDB_SUMMARY_HISTOGRAMS) {
 136                 freeg = tally_histogram(freet, HISTO_WIDTH, HISTO_HEIGHT);
 137                 usedg = tally_histogram(used, HISTO_WIDTH, HISTO_HEIGHT);
 138                 deadg = tally_histogram(dead, HISTO_WIDTH, HISTO_HEIGHT);
 139                 extrag = tally_histogram(extra, HISTO_WIDTH, HISTO_HEIGHT);
 140                 hashg = tally_histogram(hash, HISTO_WIDTH, HISTO_HEIGHT);
 141         } else {
 142                 freeg = usedg = deadg = extrag = hashg = NULL;
 143         }
 144
 145         /* 20 is max length of a %zu. */
 146         len = strlen(SUMMARY_FORMAT) + 22*20 + 1
 147                 + (freeg ? strlen(freeg) : 0)
 148                 + (usedg ? strlen(usedg) : 0)
 149                 + (deadg ? strlen(deadg) : 0)
 150                 + (extrag ? strlen(extrag) : 0)
 151                 + (hashg ? strlen(hashg) : 0);
 152         ret = malloc(len);
 153         if (!ret)
 154                 goto unlock;
 155
 156         sprintf(ret, SUMMARY_FORMAT,
 157                 tdb->map_size,
 158                 tally_num(used),
 159                 tally_min(used), tally_mean(used), tally_max(used),
 160                 usedg ? usedg : "",
 161                 tally_min(extra), tally_mean(extra), tally_max(extra),
 162                 extrag ? extrag : "",
 163                 tally_num(dead),
 164                 tally_min(dead), tally_mean(dead), tally_max(dead),
 165                 deadg ? deadg : "",
 166                 tally_num(freet),
 167                 tally_min(freet), tally_mean(freet), tally_max(freet),
 168                 freeg ? freeg : "",
 169                 tally_num(hash),
 170                 tally_min(hash), tally_mean(hash), tally_max(hash),
 171                 hashg ? hashg : "",
 172                 tally_total(used, NULL),
 173                 tally_total(used, NULL) * 100.0 / tdb->map_size);
 174
 175 unlock:
 176         free(freeg);
 177         free(usedg);
 178         free(deadg);
 179         free(extrag);
 180         free(hashg);
 181         free(freet);
 182         free(used);
 183         free(dead);
 184         free(extra);
 185         free(hash);
 186         if (locked) {
 187                 tdb_unlockall_read(tdb);
 188         }
 189         return ret;
 190 }