func()

in plugins/inputs/mysql/mysql.go [1301:1427]

• 115 lines of code
• 6 McCabe index (conditional complexity)

func (m *Mysql) gatherPerfTableLockWaits(db *sql.DB, serv string, acc telegraf.Accumulator) error {
	// check if table exists,
	// if performance_schema is not enabled, tables do not exist
	// then there is no need to scan them
	var tableName string
	err := db.QueryRow(perfSchemaTablesQuery, "table_lock_waits_summary_by_table").Scan(&tableName)
	switch {
	case err == sql.ErrNoRows:
		return nil
	case err != nil:
		return err
	}

	rows, err := db.Query(perfTableLockWaitsQuery)
	if err != nil {
		return err
	}
	defer rows.Close()

	servtag := getDSNTag(serv)

	var (
		objectSchema               string
		objectName                 string
		countReadNormal            float64
		countReadWithSharedLocks   float64
		countReadHighPriority      float64
		countReadNoInsert          float64
		countReadExternal          float64
		countWriteAllowWrite       float64
		countWriteConcurrentInsert float64
		countWriteLowPriority      float64
		countWriteNormal           float64
		countWriteExternal         float64
		timeReadNormal             float64
		timeReadWithSharedLocks    float64
		timeReadHighPriority       float64
		timeReadNoInsert           float64
		timeReadExternal           float64
		timeWriteAllowWrite        float64
		timeWriteConcurrentInsert  float64
		timeWriteLowPriority       float64
		timeWriteNormal            float64
		timeWriteExternal          float64
	)

	for rows.Next() {
		err = rows.Scan(
			&objectSchema,
			&objectName,
			&countReadNormal,
			&countReadWithSharedLocks,
			&countReadHighPriority,
			&countReadNoInsert,
			&countReadExternal,
			&countWriteAllowWrite,
			&countWriteConcurrentInsert,
			&countWriteLowPriority,
			&countWriteNormal,
			&countWriteExternal,
			&timeReadNormal,
			&timeReadWithSharedLocks,
			&timeReadHighPriority,
			&timeReadNoInsert,
			&timeReadExternal,
			&timeWriteAllowWrite,
			&timeWriteConcurrentInsert,
			&timeWriteLowPriority,
			&timeWriteNormal,
			&timeWriteExternal,
		)

		if err != nil {
			return err
		}
		tags := map[string]string{
			"server": servtag,
			"schema": objectSchema,
			"table":  objectName,
		}

		sqlLWTags := copyTags(tags)
		sqlLWTags["perf_query"] = "sql_lock_waits_total"
		sqlLWFields := map[string]interface{}{
			"read_normal":             countReadNormal,
			"read_with_shared_locks":  countReadWithSharedLocks,
			"read_high_priority":      countReadHighPriority,
			"read_no_insert":          countReadNoInsert,
			"write_normal":            countWriteNormal,
			"write_allow_write":       countWriteAllowWrite,
			"write_concurrent_insert": countWriteConcurrentInsert,
			"write_low_priority":      countWriteLowPriority,
		}
		acc.AddFields("mysql_perf_schema", sqlLWFields, sqlLWTags)

		externalLWTags := copyTags(tags)
		externalLWTags["perf_query"] = "external_lock_waits_total"
		externalLWFields := map[string]interface{}{
			"read":  countReadExternal,
			"write": countWriteExternal,
		}
		acc.AddFields("mysql_perf_schema", externalLWFields, externalLWTags)

		sqlLWSecTotalTags := copyTags(tags)
		sqlLWSecTotalTags["perf_query"] = "sql_lock_waits_seconds_total"
		sqlLWSecTotalFields := map[string]interface{}{
			"read_normal":             timeReadNormal / picoSeconds,
			"read_with_shared_locks":  timeReadWithSharedLocks / picoSeconds,
			"read_high_priority":      timeReadHighPriority / picoSeconds,
			"read_no_insert":          timeReadNoInsert / picoSeconds,
			"write_normal":            timeWriteNormal / picoSeconds,
			"write_allow_write":       timeWriteAllowWrite / picoSeconds,
			"write_concurrent_insert": timeWriteConcurrentInsert / picoSeconds,
			"write_low_priority":      timeWriteLowPriority / picoSeconds,
		}
		acc.AddFields("mysql_perf_schema", sqlLWSecTotalFields, sqlLWSecTotalTags)

		externalLWSecTotalTags := copyTags(tags)
		externalLWSecTotalTags["perf_query"] = "external_lock_waits_seconds_total"
		externalLWSecTotalFields := map[string]interface{}{
			"read":  timeReadExternal / picoSeconds,
			"write": timeWriteExternal / picoSeconds,
		}
		acc.AddFields("mysql_perf_schema", externalLWSecTotalFields, externalLWSecTotalTags)
	}
	return nil
}