/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*======
This file is part of TokuDB


Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.

    TokuDBis is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation.

    TokuDB 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with TokuDB.  If not, see <http://www.gnu.org/licenses/>.

======= */

#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."

#ifndef _TOKUDB_STATUS_H
#define _TOKUDB_STATUS_H

// These are keys that will be used for retrieving metadata in status.tokudb
// To get the version, one looks up the value associated with key hatoku_version
// in status.tokudb
typedef ulonglong HA_METADATA_KEY;
#define hatoku_old_version 0
#define hatoku_capabilities 1
#define hatoku_max_ai 2 //maximum auto increment value found so far
#define hatoku_ai_create_value 3
#define hatoku_key_name 4
#define hatoku_frm_data 5
#define hatoku_new_version 6
#define hatoku_cardinality 7

// use a very small pagesize for the status dictionary
#define status_dict_pagesize 1024

namespace tokudb {

    // get the value for a given key in the status dictionary. copy the value to the supplied buffer.
    // returns 0 if successful.
    int get_status(DB *status_db, DB_TXN *txn, HA_METADATA_KEY k, void *p, size_t s, size_t *sp) {
        DBT key = {}; key.data = &k; key.size = sizeof k;
        DBT val = {}; val.data = p; val.ulen = (uint32_t) s; val.flags = DB_DBT_USERMEM;
        int error = status_db->get(status_db, txn, &key, &val, 0);
        if (error == 0) {
            *sp = val.size;
        }
        return error;
    }

    // get the value for a given key in the status dictionary. put the value in a realloced buffer.
    // returns 0 if successful.
    int get_status_realloc(DB *status_db, DB_TXN *txn, HA_METADATA_KEY k, void **pp, size_t *sp) {
        DBT key = {}; key.data = &k; key.size = sizeof k;
        DBT val = {}; val.data = *pp; val.size = (uint32_t) *sp; val.flags = DB_DBT_REALLOC;
        int error = status_db->get(status_db, txn, &key, &val, 0);
        if (error == 0) {
            *pp = val.data;
            *sp = val.size;
        }
        return error;
    }

    // write a key value pair into the status dictionary, overwriting the previous value if any.
    // auto create a txn if necessary.
    // returns 0 if successful.
    int write_metadata(DB *status_db, void *key_data, uint key_size, void* val_data, uint val_size, DB_TXN *txn) {
        DBT key = {}; key.data = key_data; key.size = key_size;
        DBT value = {}; value.data = val_data; value.size = val_size;
        int error = status_db->put(status_db, txn, &key, &value, 0);
        return error;
    }

    // write a key value pair into the status dictionary, overwriting the previous value if any.
    // the key must be a HA_METADATA_KEY.
    // returns 0 if successful.
    int write_to_status(DB *status_db, HA_METADATA_KEY curr_key_data, void *val, size_t val_size, DB_TXN *txn) {
        return write_metadata(status_db, &curr_key_data, sizeof curr_key_data, val, val_size, txn);
    }

    // remove a key from the status dictionary.
    // auto create a txn if necessary.
    // returns 0 if successful.
    int remove_metadata(DB *status_db, void *key_data, uint key_size, DB_TXN *txn) {
        DBT key = {}; key.data = key_data; key.size = key_size;
        int error = status_db->del(status_db, txn, &key, DB_DELETE_ANY);
        return error;
    }

    // remove a key from the status dictionary.
    // the key must be a HA_METADATA_KEY
    // returns 0 if successful.
    int remove_from_status(DB *status_db, HA_METADATA_KEY curr_key_data, DB_TXN *txn) {
        return remove_metadata(status_db, &curr_key_data, sizeof curr_key_data, txn);
    }

    int close_status(DB **status_db_ptr) {
        int error = 0;
        DB *status_db = *status_db_ptr;
        if (status_db) {
            error = status_db->close(status_db, 0);
            if (error == 0)
                *status_db_ptr = NULL;
        }
        return error;
    }

    int create_status(DB_ENV *env, DB **status_db_ptr, const char *name, DB_TXN *txn) {
        int error;
        DB *status_db = NULL;

        error = db_create(&status_db, env, 0);
        if (error == 0) {
            error = status_db->set_pagesize(status_db, status_dict_pagesize);
        }
        if (error == 0) {
            error = status_db->open(status_db, txn, name, NULL, DB_BTREE, DB_CREATE | DB_EXCL, 0);
        }
        if (error == 0) {
            *status_db_ptr = status_db;
        } else {
            int r = close_status(&status_db);
            assert(r == 0);
        }
        return error;
    }

    int open_status(DB_ENV *env, DB **status_db_ptr, const char *name, DB_TXN *txn) {
        int error = 0;
        DB *status_db = NULL;
        error = db_create(&status_db, env, 0);
        if (error == 0) {
            error = status_db->open(status_db, txn, name, NULL, DB_BTREE, DB_THREAD, 0);
        }
        if (error == 0) {
            uint32_t pagesize = 0;
            error = status_db->get_pagesize(status_db, &pagesize);                
            if (error == 0 && pagesize > status_dict_pagesize) {
                error = status_db->change_pagesize(status_db, status_dict_pagesize);
            }
        }
        if (error == 0) {
            *status_db_ptr = status_db;
        } else {
            int r = close_status(&status_db);
            assert(r == 0);
        }
        return error;
    }
}

#endif