Zabbix

/*

** Zabbix

** Copyright (C) 2001-2022 Zabbix SIA

**

** This program is free software; you can redistribute it and/or modify

** it under the terms of the GNU General Public License as published by

** the Free Software Foundation; either version 2 of the License, or

** (at your option) any later version.

**

** This program 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 this program; if not, write to the Free Software

** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

**/

​

package postgres

​

import (

    "context"

    "errors"

​

    "git.zabbix.com/ap/plugin-support/zbxerr"

    "github.com/jackc/pgx/v4"

)

​

// walHandler executes select from directory which contains wal files and returns JSON if all is OK or nil otherwise.

func walHandler(ctx context.Context, conn PostgresClient,

    _ string, _ map[string]string, _ ...string) (interface{}, error) {

    var walJSON string

​

    query := `SELECT row_to_json(T)

                FROM (

                    SELECT

                        CASE

                            WHEN pg_is_in_recovery() THEN 0

                            ELSE pg_wal_lsn_diff(pg_current_wal_lsn(),'0/00000000')

                        END AS WRITE,

                        CASE 

                            WHEN NOT pg_is_in_recovery() THEN 0

                            ELSE pg_wal_lsn_diff(pg_last_wal_receive_lsn(),'0/00000000')

                        END AS RECEIVE,

                        count(*)

                        FROM pg_ls_waldir() AS COUNT

                    ) T;`

​

    row, err := conn.QueryRow(ctx, query)

    if err != nil {

        return nil, zbxerr.ErrorCannotFetchData.Wrap(err)

    }

​

    err = row.Scan(&walJSON)

    if err != nil {

        if errors.Is(err, pgx.ErrNoRows) {

            return nil, zbxerr.ErrorEmptyResult.Wrap(err)

        }

​

        return nil, zbxerr.ErrorCannotFetchData.Wrap(err)

    }

​

    return walJSON, nil

}