source: vendor/current/lib/tdb/common/summary.c

 /*
   Trivial Database: human-readable summary code
   Copyright (C) Rusty Russell 2010

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "tdb_private.h"

#define SUMMARY_FORMAT \
        "Size of file/data: %llu/%zu\n" \
        "Header offset/logical size: %zu/%zu\n" \
        "Number of records: %zu\n" \
        "Incompatible hash: %s\n" \
        "Active/supported feature flags: 0x%08x/0x%08x\n" \
        "Robust mutexes locking: %s\n" \
        "Smallest/average/largest keys: %zu/%zu/%zu\n" \
        "Smallest/average/largest data: %zu/%zu/%zu\n" \
        "Smallest/average/largest padding: %zu/%zu/%zu\n" \
        "Number of dead records: %zu\n" \
        "Smallest/average/largest dead records: %zu/%zu/%zu\n" \
        "Number of free records: %zu\n" \
        "Smallest/average/largest free records: %zu/%zu/%zu\n" \
        "Number of hash chains: %zu\n" \
        "Smallest/average/largest hash chains: %zu/%zu/%zu\n" \
        "Number of uncoalesced records: %zu\n" \
        "Smallest/average/largest uncoalesced runs: %zu/%zu/%zu\n" \
        "Percentage keys/data/padding/free/dead/rechdrs&tailers/hashes: %.0f/%.0f/%.0f/%.0f/%.0f/%.0f/%.0f\n"

/* We don't use tally module, to keep upstream happy. */
struct tally {
        size_t min, max, total;
        size_t num;
};

static void tally_init(struct tally *tally)
{
        tally->total = 0;
        tally->num = 0;
        tally->min = tally->max = 0;
}

static void tally_add(struct tally *tally, size_t len)
{
        if (tally->num == 0)
                tally->max = tally->min = len;
        else if (len > tally->max)
                tally->max = len;
        else if (len < tally->min)
                tally->min = len;
        tally->num++;
        tally->total += len;
}

static size_t tally_mean(const struct tally *tally)
{
        if (!tally->num)
                return 0;
        return tally->total / tally->num;
}

static size_t get_hash_length(struct tdb_context *tdb, unsigned int i)
{
        tdb_off_t rec_ptr;
        size_t count = 0;

        if (tdb_ofs_read(tdb, TDB_HASH_TOP(i), &rec_ptr) == -1)
                return 0;

        /* keep looking until we find the right record */
        while (rec_ptr) {
                struct tdb_record r;
                ++count;
                if (tdb_rec_read(tdb, rec_ptr, &r) == -1)
                        return 0;
                rec_ptr = r.next;
        }
        return count;
}

_PUBLIC_ char *tdb_summary(struct tdb_context *tdb)
{
        off_t file_size;
        tdb_off_t off, rec_off;
        struct tally freet, keys, data, dead, extra, hashval, uncoal;
        struct tdb_record rec;
        char *ret = NULL;
        bool locked;
        size_t unc = 0;
        int len;
        struct tdb_record recovery;

        /* Read-only databases use no locking at all: it's best-effort.
         * We may have a write lock already, so skip that case too. */
        if (tdb->read_only || tdb->allrecord_lock.count != 0) {
                locked = false;
        } else {
                if (tdb_lockall_read(tdb) == -1)
                        return NULL;
                locked = true;
        }

        if (tdb_recovery_area(tdb, tdb->methods, &rec_off, &recovery) != 0) {
                goto unlock;
        }

        tally_init(&freet);
        tally_init(&keys);
        tally_init(&data);
        tally_init(&dead);
        tally_init(&extra);
        tally_init(&hashval);
        tally_init(&uncoal);

        for (off = TDB_DATA_START(tdb->hash_size);
             off < tdb->map_size - 1;
             off += sizeof(rec) + rec.rec_len) {
                if (tdb->methods->tdb_read(tdb, off, &rec, sizeof(rec),
                                           DOCONV()) == -1)
                        goto unlock;
                switch (rec.magic) {
                case TDB_MAGIC:
                        tally_add(&keys, rec.key_len);
                        tally_add(&data, rec.data_len);
                        tally_add(&extra, rec.rec_len - (rec.key_len
                                                         + rec.data_len));
                        if (unc > 1)
                                tally_add(&uncoal, unc - 1);
                        unc = 0;
                        break;
                case TDB_FREE_MAGIC:
                        tally_add(&freet, rec.rec_len);
                        unc++;
                        break;
                /* If we crash after ftruncate, we can get zeroes or fill. */
                case TDB_RECOVERY_INVALID_MAGIC:
                case 0x42424242:
                        unc++;
                        /* If it's a valid recovery, we can trust rec_len. */
                        if (off != rec_off) {
                                rec.rec_len = tdb_dead_space(tdb, off)
                                        - sizeof(rec);
                        }
                        /* Fall through */
                case TDB_DEAD_MAGIC:
                        tally_add(&dead, rec.rec_len);
                        break;
                default:
                        TDB_LOG((tdb, TDB_DEBUG_ERROR,
                                 "Unexpected record magic 0x%x at offset %u\n",
                                 rec.magic, off));
                        goto unlock;
                }
        }
        if (unc > 1)
                tally_add(&uncoal, unc - 1);

        for (off = 0; off < tdb->hash_size; off++)
                tally_add(&hashval, get_hash_length(tdb, off));

        file_size = tdb->hdr_ofs + tdb->map_size;

        len = asprintf(&ret, SUMMARY_FORMAT,
                 (unsigned long long)file_size, keys.total+data.total,
                 (size_t)tdb->hdr_ofs, (size_t)tdb->map_size,
                 keys.num,
                 (tdb->hash_fn == tdb_jenkins_hash)?"yes":"no",
                 (unsigned)tdb->feature_flags, TDB_SUPPORTED_FEATURE_FLAGS,
                 (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX)?"yes":"no",
                 keys.min, tally_mean(&keys), keys.max,
                 data.min, tally_mean(&data), data.max,
                 extra.min, tally_mean(&extra), extra.max,
                 dead.num,
                 dead.min, tally_mean(&dead), dead.max,
                 freet.num,
                 freet.min, tally_mean(&freet), freet.max,
                 hashval.num,
                 hashval.min, tally_mean(&hashval), hashval.max,
                 uncoal.total,
                 uncoal.min, tally_mean(&uncoal), uncoal.max,
                 keys.total * 100.0 / file_size,
                 data.total * 100.0 / file_size,
                 extra.total * 100.0 / file_size,
                 freet.total * 100.0 / file_size,
                 dead.total * 100.0 / file_size,
                 (keys.num + freet.num + dead.num)
                 * (sizeof(struct tdb_record) + sizeof(uint32_t))
                 * 100.0 / file_size,
                 tdb->hash_size * sizeof(tdb_off_t)
                 * 100.0 / file_size);
        if (len == -1) {
                goto unlock;
        }

unlock:
        if (locked) {
                tdb_unlockall_read(tdb);
        }
        return ret;
}