graphite.go

package graphite

import (
	"bytes"
	"fmt"
	"log"
	"net"
	"time"
)

// Graphite is a struct that defines the relevant properties of a graphite
// connection
type Graphite struct {
	Address string
	Timeout time.Duration
	Prefix  string
	conn    net.Conn
	nop     bool
}

// defaultTimeout is the default number of seconds that we're willing to wait
// before forcing the connection establishment to fail
const defaultTimeout = 5

// IsNop is a getter for *graphite.Graphite.nop
func (graphite *Graphite) IsNop() bool {
	if graphite.nop {
		return true
	}
	return false
}

// Given a Graphite struct, Connect populates the Graphite.conn field with an
// appropriate TCP connection
func (graphite *Graphite) Connect() error {
	if !graphite.IsNop() {
		if graphite.conn != nil {
			graphite.conn.Close()
		}

		if graphite.Timeout == 0 {
			graphite.Timeout = defaultTimeout * time.Second
		}

		conn, err := net.DialTimeout("tcp", graphite.Address, graphite.Timeout)
		if err != nil {
			return err
		}

		graphite.conn = conn
	}

	return nil
}

// Given a Graphite struct, Disconnect closes the Graphite.conn field
func (graphite *Graphite) Disconnect() error {
	err := graphite.conn.Close()
	graphite.conn = nil
	return err
}

// Given a Metric struct, the SendMetric method sends the supplied metric to the
// Graphite connection that the method is called upon
func (graphite *Graphite) SendMetric(metric Metric) error {
	metrics := make([]Metric, 1)
	metrics[0] = metric

	return graphite.sendMetrics(metrics)
}

// Given a slice of Metrics, the SendMetrics method sends the metrics, as a
// batch, to the Graphite connection that the method is called upon
func (graphite *Graphite) SendMetrics(metrics []Metric) error {
	return graphite.sendMetrics(metrics)
}

// sendMetrics is an internal function that is used to write to the TCP
// connection in order to communicate metrics to the remote Graphite host
func (graphite *Graphite) sendMetrics(metrics []Metric) error {
	zeroed_metric := Metric{} // ignore unintialized metrics
	if !graphite.IsNop() {
		buf := bytes.NewBufferString("")
		for _, metric := range metrics {
			if metric == zeroed_metric {
				continue // ignore unintialized metrics
			}
			if metric.Timestamp == 0 {
				metric.Timestamp = time.Now().Unix()
			}
			metric_name := ""
			if graphite.Prefix != "" {
				metric_name = fmt.Sprintf("%s.%s", graphite.Prefix, metric.Name)
			} else {
				metric_name = metric.Name
			}
			buf.WriteString(fmt.Sprintf("%s %s %d\n", metric_name, metric.Value, metric.Timestamp))
		}
		_, err := graphite.conn.Write(buf.Bytes())
		//fmt.Print("Sent msg:", buf.String(), "'")
		if err != nil {
			return err
		}
	} else {
		for _, metric := range metrics {
			log.Printf("Graphite: %s\n", metric)
		}
	}
	return nil
}

// The SimpleSend method can be used to just pass a metric name and value and
// have it be sent to the Graphite host with the current timestamp
func (graphite *Graphite) SimpleSend(stat string, value string) error {
	metrics := make([]Metric, 1)
	metrics[0] = NewMetric(stat, value, time.Now().Unix())
	err := graphite.sendMetrics(metrics)
	if err != nil {
		return err
	}
	return nil
}

// NewGraphiteHost is a factory method that's used to create a new Graphite
// connection given a hostname and a port number
func NewGraphite(host string, port int) (*Graphite, error) {
	address := fmt.Sprintf("%s:%d", host, port)

	Graphite := &Graphite{Address: address}
	err := Graphite.Connect()
	if err != nil {
		return nil, err
	}

	return Graphite, nil
}

// NewGraphiteHost is a factory method that's used to create a new Graphite
// connection given an address string understood by net.Dial
func NewGraphiteFromAddress(address string) (*Graphite, error) {
	Graphite := &Graphite{Address: address}
	err := Graphite.Connect()
	if err != nil {
		return nil, err
	}

	return Graphite, nil
}

// NewGraphiteNop is a factory method that returns a Graphite struct but will
// not actually try to send any packets to a remote host and, instead, will just
// log. This is useful if you want to use Graphite in a project but don't want
// to make Graphite a requirement for the project.
func NewGraphiteNop(host string, port int) *Graphite {
	address := fmt.Sprintf("%s:%d", host, port)

	graphiteNop := &Graphite{Address: address, nop: true}
	return graphiteNop
}

// NewGraphiteNop is a factory method that returns a Graphite struct but will
// not actually try to send any packets to a remote host and, instead, will just
// log. This is useful if you want to use Graphite in a project but don't want
// to make Graphite a requirement for the project.
func NewGraphiteNopFromAdress(address string) *Graphite {
	graphiteNop := &Graphite{Address: address, nop: true}
	return graphiteNop
}