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
  20 #define SUMMARY_FORMAT \
  21         "Size of file/data: %u/%zu\n" \
  22         "Number of records: %zu\n" \
  23         "Smallest/average/largest keys: %zu/%zu/%zu\n" \
  24         "Smallest/average/largest data: %zu/%zu/%zu\n" \
  25         "Smallest/average/largest padding: %zu/%zu/%zu\n" \
  26         "Number of dead records: %zu\n" \
  27         "Smallest/average/largest dead records: %zu/%zu/%zu\n" \
  28         "Number of free records: %zu\n" \
  29         "Smallest/average/largest free records: %zu/%zu/%zu\n" \
  30         "Number of hash chains: %zu\n" \
  31         "Smallest/average/largest hash chains: %zu/%zu/%zu\n" \
  32         "Number of uncoalesced records: %zu\n" \
  33         "Smallest/average/largest uncoalesced runs: %zu/%zu/%zu\n" \
  34         "Percentage keys/data/padding/free/dead/rechdrs&tailers/hashes: %.0f/%.0f/%.0f/%.0f/%.0f/%.0f/%.0f\n"
  35
  36 /* We don't use tally module, to keep upstream happy. */
  37 struct tally {
  38         size_t min, max, total;
  39         size_t num;
  40 };
  41
  42 static void tally_init(struct tally *tally)
  43 {
  44         tally->total = 0;
  45         tally->num = 0;
  46         tally->min = tally->max = 0;
  47 }
  48
  49 static void tally_add(struct tally *tally, size_t len)
  50 {
  51         if (tally->num == 0)
  52                 tally->max = tally->min = len;
  53         else if (len > tally->max)
  54                 tally->max = len;
  55         else if (len < tally->min)
  56                 tally->min = len;
  57         tally->num++;
  58         tally->total += len;
  59 }
  60
  61 static size_t tally_mean(const struct tally *tally)
  62 {
  63         if (!tally->num)
  64                 return 0;
  65         return tally->total / tally->num;
  66 }
  67
  68 static size_t get_hash_length(struct tdb_context *tdb, unsigned int i)
  69 {
  70         tdb_off_t rec_ptr;
  71         size_t count = 0;
  72
  73         if (tdb_ofs_read(tdb, TDB_HASH_TOP(i), &rec_ptr) == -1)
  74                 return 0;
  75
  76         /* keep looking until we find the right record */
  77         while (rec_ptr) {
  78                 struct tdb_record r;
  79                 ++count;
  80                 if (tdb_rec_read(tdb, rec_ptr, &r) == -1)
  81                         return 0;
  82                 rec_ptr = r.next;
  83         }
  84         return count;
  85 }
  86
  87 char *tdb_summary(struct tdb_context *tdb)
  88 {
  89         tdb_off_t off;
  90         struct tally freet, keys, data, dead, extra, hash, uncoal;
  91         struct tdb_record rec;
  92         char *ret = NULL;
  93         bool locked;
  94         size_t len, unc = 0;
  95
  96         /* Read-only databases use no locking at all: it's best-effort.
  97          * We may have a write lock already, so skip that case too. */
  98         if (tdb->read_only || tdb->allrecord_lock.count != 0) {
  99                 locked = false;
 100         } else {
 101                 if (tdb_lockall_read(tdb) == -1)
 102                         return NULL;
 103                 locked = true;
 104         }
 105
 106         tally_init(&freet);
 107         tally_init(&keys);
 108         tally_init(&data);
 109         tally_init(&dead);
 110         tally_init(&extra);
 111         tally_init(&hash);
 112         tally_init(&uncoal);
 113
 114         for (off = TDB_DATA_START(tdb->header.hash_size);
 115              off < tdb->map_size - 1;
 116              off += sizeof(rec) + rec.rec_len) {
 117                 if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec),
 118                                            DOCONV()) == -1)
 119                         goto unlock;
 120                 switch (rec.magic) {
 121                 case TDB_MAGIC:
 122                         tally_add(&keys, rec.key_len);
 123                         tally_add(&data, rec.data_len);
 124                         tally_add(&extra, rec.rec_len - (rec.key_len
 125                                                          + rec.data_len));
 126                         if (unc > 1)
 127                                 tally_add(&uncoal, unc - 1);
 128                         unc = 0;
 129                         break;
 130                 case TDB_FREE_MAGIC:
 131                         tally_add(&freet, rec.rec_len);
 132                         unc++;
 133                         break;
 134                 /* If we crash after ftruncate, we can get zeroes or fill. */
 135                 case TDB_RECOVERY_INVALID_MAGIC:
 136                 case 0x42424242:
 137                         unc++;
 138                         rec.rec_len = tdb_dead_space(tdb, off) - sizeof(rec);
 139                         /* Fall through */
 140                 case TDB_DEAD_MAGIC:
 141                         tally_add(&dead, rec.rec_len);
 142                         break;
 143                 default:
 144                         TDB_LOG((tdb, TDB_DEBUG_ERROR,
 145                                  "Unexpected record magic 0x%x at offset %d\n",
 146                                  rec.magic, off));
 147                         goto unlock;
 148                 }
 149         }
 150         if (unc > 1)
 151                 tally_add(&uncoal, unc - 1);
 152
 153         for (off = 0; off < tdb->header.hash_size; off++)
 154                 tally_add(&hash, get_hash_length(tdb, off));
 155
 156         /* 20 is max length of a %zu. */
 157         len = strlen(SUMMARY_FORMAT) + 35*20 + 1;
 158         ret = malloc(len);
 159         if (!ret)
 160                 goto unlock;
 161
 162         sprintf(ret, SUMMARY_FORMAT,
 163                 tdb->map_size, keys.total+data.total,
 164                 keys.num,
 165                 keys.min, tally_mean(&keys), keys.max,
 166                 data.min, tally_mean(&data), data.max,
 167                 extra.min, tally_mean(&extra), extra.max,
 168                 dead.num,
 169                 dead.min, tally_mean(&dead), dead.max,
 170                 freet.num,
 171                 freet.min, tally_mean(&freet), freet.max,
 172                 hash.num,
 173                 hash.min, tally_mean(&hash), hash.max,
 174                 uncoal.total,
 175                 uncoal.min, tally_mean(&uncoal), uncoal.max,
 176                 keys.total * 100.0 / tdb->map_size,
 177                 data.total * 100.0 / tdb->map_size,
 178                 extra.total * 100.0 / tdb->map_size,
 179                 freet.total * 100.0 / tdb->map_size,
 180                 dead.total * 100.0 / tdb->map_size,
 181                 (keys.num + freet.num + dead.num)
 182                 * (sizeof(struct tdb_record) + sizeof(uint32_t))
 183                 * 100.0 / tdb->map_size,
 184                 tdb->header.hash_size * sizeof(tdb_off_t)
 185                 * 100.0 / tdb->map_size);
 186
 187 unlock:
 188         if (locked) {
 189                 tdb_unlockall_read(tdb);
 190         }
 191         return ret;
 192 }