/*

   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;

  struct tdb_chainwalk_ctx chainwalk;

  size_t count = 0;

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

    return 0;

  tdb_chainwalk_init(&chainwalk, rec_ptr);

  /* keep looking until we find the right record */

  while (rec_ptr) {

    struct tdb_record r;

    bool ok;

    ++count;

    if (tdb_rec_read(tdb, rec_ptr, &r) == -1)

      return 0;

    rec_ptr = r.next;

    ok = tdb_chainwalk_check(tdb, &chainwalk, rec_ptr);

    if (!ok) {

      return SIZE_MAX;

    }

  }

  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;

}