forked from thraxil/cbp
/
cbp.go
150 lines (129 loc) · 3.33 KB
/
cbp.go
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package main
import (
"flag"
"io"
"log"
"net"
"github.com/peterbourgon/g2s"
"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 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()
}
}
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)
}
cb := circuit.NewRateBreaker(*threshold, *minSamples)
events := cb.Subscribe()
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)
}
if *verbose {
go func() {
for {
e := <-events
switch e {
case circuit.BreakerTripped:
log.Println("breaker tripped")
case circuit.BreakerReset:
log.Println("breaker reset")
case circuit.BreakerFail:
log.Println("breaker fail")
case circuit.BreakerReady:
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)
for {
conn, err := listener.AcceptTCP()
if err != nil {
log.Fatal("error starting listener: ", err)
}
pending <- conn
}
}