firehol/netdata

// SPDX-License-Identifier: GPL-3.0-or-later

package postgres

import (
    "context"
    "database/sql"
)

func (p *Postgres) doQueryRow(query string, v any) error {
    ctx, cancel := context.WithTimeout(context.Background(), p.Timeout.Duration())
    defer cancel()

    return p.db.QueryRowContext(ctx, query).Scan(v)
}

func (p *Postgres) doDBQueryRow(db *sql.DB, query string, v any) error {
    ctx, cancel := context.WithTimeout(context.Background(), p.Timeout.Duration())
    defer cancel()

    return db.QueryRowContext(ctx, query).Scan(v)
}

func (p *Postgres) doQuery(query string, assign func(column, value string, rowEnd bool)) error {
    return p.doDBQuery(p.db, query, assign)
}

func (p *Postgres) doDBQuery(db *sql.DB, query string, assign func(column, value string, rowEnd bool)) error {
    ctx, cancel := context.WithTimeout(context.Background(), p.Timeout.Duration())
    defer cancel()

    rows, err := db.QueryContext(ctx, query)
    if err != nil {
        return err
    }
    defer func() { _ = rows.Close() }()

    return readRows(rows, assign)
}

func readRows(rows *sql.Rows, assign func(column, value string, rowEnd bool)) error {
    if assign == nil {
        return nil
    }

    columns, err := rows.Columns()
    if err != nil {
        return err
    }

    values := makeValues(len(columns))

    for rows.Next() {
        if err := rows.Scan(values...); err != nil {
            return err
        }
        for i, l := 0, len(values); i < l; i++ {
            assign(columns[i], valueToString(values[i]), i == l-1)
        }
    }
    return rows.Err()
}

func valueToString(value any) string {
    v, ok := value.(*sql.NullString)
    if !ok || !v.Valid {
        return ""
    }
    return v.String
}

func makeValues(size int) []any {
    vs := make([]any, size)
    for i := range vs {
        vs[i] = &sql.NullString{}
    }
    return vs
}