query.go

package main

import (
	"database/sql"
	"time"
)

// Request takes a query and returns the results
type Request struct {
	query  Query
	result chan Result
}

// Query defines the model for building the queries
type Query struct {
	Hostname  string
	Starttime time.Time
	Endtime   time.Time
}

type Result struct {
	count    int
	duration time.Duration
}

const (
	baseQuery = `SELECT time_bucket('1 minute', ts) as minute,
	MAX(usage) as max_usage,
	MIN(usage) as min_usage
	FROM cpu_usage
	WHERE host = $1 AND ts BETWEEN $2 AND $3 
	GROUP BY minute`
)

func (r *Request) runQuery(db *sql.DB) Result {

	parsed, err := db.Prepare(baseQuery)
	checkError(err)

	query := r.query
	resultCount := 0

	var duration time.Duration

	start := time.Now()

	rows, err := parsed.Query(query.Hostname, query.Starttime, query.Endtime)

	if err == nil {
		duration = time.Now().Sub(start)
		for rows.Next() {
			resultCount++
		}
	}

	return Result{resultCount, duration}
}