/
cbp.go
184 lines (160 loc) · 4.2 KB
/
cbp.go
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package main
import (
"expvar"
"flag"
"io"
"log"
"net"
"net/http"
"time"
"github.com/peterbourgon/g2s"
circuit "github.com/rubyist/circuitbreaker"
)
var localAddr = flag.String("l", "localhost:9999", "local address")
var remoteAddr = flag.String("r", "localhost:80", "remote address")
var threshold = flag.Float64("t", 0.5, "error threshold for tripping")
var minSamples = flag.Int64("ms", 5, "minimum samples")
var windowTime = flag.Int64("window-time", 10000, "window time (ms)")
var windowBuckets = flag.Int64("window-buckets", 10, "window Buckets")
var expvarAddr = flag.String("e", "localhost:9998", "expvar address")
var verbose = flag.Bool("v", false, "verbose")
var statsdHost = flag.String("statsd", "", "statsd host. eg: localhost8125")
var metricBase = flag.String("metric-base", "", "statsd metric base")
var metricName = flag.String("metric-name", "", "statsd metric name")
func proxy(cliConn *net.TCPConn, rAddr *net.TCPAddr) error {
srvConn, err := net.DialTCP("tcp", nil, rAddr)
if err != nil {
cliConn.Close()
return err
}
defer srvConn.Close()
// channels to wait on the close event for each connection
serverClosed := make(chan struct{}, 1)
clientClosed := make(chan struct{}, 1)
go broker(srvConn, cliConn, clientClosed)
go broker(cliConn, srvConn, serverClosed)
var waitFor chan struct{}
select {
case <-clientClosed:
// the client closed first
srvConn.SetLinger(0)
srvConn.CloseRead()
waitFor = serverClosed
case <-serverClosed:
cliConn.CloseRead()
waitFor = clientClosed
}
<-waitFor
return nil
}
func broker(dst, src net.Conn, srcClosed chan struct{}) {
_, err := io.Copy(dst, src)
if err != nil {
if *verbose {
log.Printf("Copy error: %s", err)
}
}
if err := src.Close(); err != nil {
if *verbose {
log.Printf("Close error: %s", err)
}
}
srcClosed <- struct{}{}
}
func handleConn(in <-chan *net.TCPConn, out chan<- *net.TCPConn, rAddr *net.TCPAddr, cb *circuit.Breaker) {
for conn := range in {
cb.Call(func() error {
return proxy(conn, rAddr)
}, 0)
}
}
func closeConn(in <-chan *net.TCPConn) {
for conn := range in {
conn.Close()
}
}
var state = expvar.NewString("state")
var eventsCount = expvar.NewInt("events")
var connectionsCount = expvar.NewInt("connections")
func main() {
flag.Parse()
if *verbose {
log.Printf("%v -> %v\n", *localAddr, *remoteAddr)
}
addr, err := net.ResolveTCPAddr("tcp", *localAddr)
if err != nil {
log.Fatal("cannot resolve local address: ", err)
}
rAddr, err := net.ResolveTCPAddr("tcp", *remoteAddr)
if err != nil {
log.Fatal("cannot resolve remote address: ", err)
}
options := circuit.Options{
ShouldTrip: circuit.RateTripFunc(*threshold, *minSamples),
WindowTime: time.Duration(*windowTime) * time.Millisecond,
WindowBuckets: int(*windowBuckets),
}
cb := circuit.NewBreakerWithOptions(&options)
events := cb.Subscribe()
state.Set("ready")
if *statsdHost != "" && *metricBase != "" && *metricName != "" {
log.Println("logging to statsd")
s, err := g2s.Dial("udp", *statsdHost)
if err != nil {
log.Fatal(err)
}
panel := circuit.NewPanel()
panel.StatsPrefixf = *metricBase + ".%s"
panel.Statter = s
panel.Add(*metricName, cb)
}
go func() {
for {
e := <-events
eventsCount.Add(1)
switch e {
case circuit.BreakerTripped:
state.Set("tripped")
if *verbose {
log.Println("breaker tripped")
}
case circuit.BreakerReset:
state.Set("reset")
if *verbose {
log.Println("breaker reset")
}
case circuit.BreakerFail:
state.Set("fail")
if *verbose {
log.Println("breaker fail")
}
case circuit.BreakerReady:
state.Set("ready")
if *verbose {
log.Println("breaker ready")
}
}
}
}()
listener, err := net.ListenTCP("tcp", addr)
if err != nil {
log.Fatal("cannot bind to local port: ", err)
}
pending, complete := make(chan *net.TCPConn), make(chan *net.TCPConn)
for i := 0; i < 5; i++ {
go handleConn(pending, complete, rAddr, cb)
}
go closeConn(complete)
go func() {
// serve the expvars endpoint
http.ListenAndServe(*expvarAddr, nil)
}()
for {
conn, err := listener.AcceptTCP()
if err != nil {
log.Fatal("error starting listener: ", err)
}
connectionsCount.Add(1)
pending <- conn
}
}