mariadb/storage/tokudb/tokudb_status.h

#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