firehol/netdata

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

package oracledb

import (
    "context"
    "database/sql"
    "fmt"
    "time"
)

const precision = 1000

func (o *OracleDB) collect() (map[string]int64, error) {
    if o.db == nil {
        if err := o.openConnection(); err != nil {
            return nil, fmt.Errorf("failed to open connection: %v", err)
        }
    }

    mx := make(map[string]int64)

    // TODO: https://www.oracle.com/technical-resources/articles/schumacher-analysis.html

    if err := o.collectSysMetrics(mx); err != nil {
        return nil, fmt.Errorf("failed to collect system metrics: %v", err)
    }
    if err := o.collectSysStat(mx); err != nil {
        return nil, fmt.Errorf("failed to collect activities: %v", err)
    }
    if err := o.collectWaitClass(mx); err != nil {
        return nil, fmt.Errorf("failed to collect wait time: %v", err)
    }
    if err := o.collectTablespace(mx); err != nil {
        return nil, fmt.Errorf("failed to collect tablespace: %v", err)
    }

    return mx, nil
}

func (o *OracleDB) doQuery(query string, assign func(column, value string, lineEnd bool) error) error {
    ctx, cancel := context.WithTimeout(context.Background(), o.Timeout.Duration())
    defer cancel()

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

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

    vs := makeValues(len(columns))

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

    return rows.Err()
}

func (o *OracleDB) openConnection() error {
    db, err := sql.Open("oracle", o.DSN)
    if err != nil {
        return fmt.Errorf("error on sql open: %v", err)
    }

    db.SetConnMaxLifetime(10 * time.Minute)

    ctx, cancel := context.WithTimeout(context.Background(), o.Timeout.Duration())
    defer cancel()

    if err := db.PingContext(ctx); err != nil {
        _ = db.Close()
        return fmt.Errorf("error on pinging: %v", err)
    }

    o.db = db

    return nil
}

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

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