/
strategy.go
283 lines (236 loc) · 6.87 KB
/
strategy.go
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package strategy
import (
"bytes"
"hash/fnv"
"io"
"net"
"sort"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/nadoo/glider/common/log"
"github.com/nadoo/glider/proxy"
)
// Checker is an interface of forwarder checker.
type Checker interface {
Check()
}
// Config is strategy config struct.
type Config struct {
Strategy string
CheckWebSite string
CheckInterval int
CheckTimeout int
MaxFailures int
IntFace string
}
// forwarder slice orderd by priority
type priSlice []*proxy.Forwarder
func (p priSlice) Len() int { return len(p) }
func (p priSlice) Less(i, j int) bool { return p[i].Priority() > p[j].Priority() }
func (p priSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
// Dialer is base dialer struct.
type Dialer struct {
config *Config
fwdrs priSlice
available []*proxy.Forwarder
mu sync.RWMutex
index uint32
priority uint32
nextForwarder func(addr string) *proxy.Forwarder
}
// NewDialer returns a new strategy dialer.
func NewDialer(s []string, c *Config) proxy.Dialer {
var fwdrs []*proxy.Forwarder
for _, chain := range s {
fwdr, err := proxy.ForwarderFromURL(chain, c.IntFace)
if err != nil {
log.Fatal(err)
}
fwdr.SetMaxFailures(uint32(c.MaxFailures))
fwdrs = append(fwdrs, fwdr)
}
if len(fwdrs) == 0 {
d, err := proxy.NewDirect(c.IntFace)
if err != nil {
log.Fatal(err)
}
return d
}
if len(fwdrs) == 1 {
return fwdrs[0]
}
return newDialer(fwdrs, c)
}
// newDialer returns a new rrDialer
func newDialer(fwdrs []*proxy.Forwarder, c *Config) *Dialer {
d := &Dialer{fwdrs: fwdrs, config: c}
sort.Sort(d.fwdrs)
d.initAvailable()
if strings.IndexByte(d.config.CheckWebSite, ':') == -1 {
d.config.CheckWebSite += ":80"
}
switch c.Strategy {
case "rr":
d.nextForwarder = d.scheduleRR
log.F("forward to remote servers in round robin mode.")
case "ha":
d.nextForwarder = d.scheduleHA
log.F("forward to remote servers in high availability mode.")
case "lha":
d.nextForwarder = d.scheduleLHA
log.F("forward to remote servers in latency based high availability mode.")
case "dh":
d.nextForwarder = d.scheduleDH
log.F("forward to remote servers in destination hashing mode.")
default:
d.nextForwarder = d.scheduleRR
log.F("not supported forward mode '%s', use round robin mode.", c.Strategy)
}
for _, f := range fwdrs {
f.AddHandler(d.onStatusChanged)
}
return d
}
// Addr returns forwarder's address.
func (d *Dialer) Addr() string { return "STRATEGY" }
// Dial connects to the address addr on the network net.
func (d *Dialer) Dial(network, addr string) (net.Conn, error) {
return d.NextDialer(addr).Dial(network, addr)
}
// DialUDP connects to the given address.
func (d *Dialer) DialUDP(network, addr string) (pc net.PacketConn, writeTo net.Addr, err error) {
return d.NextDialer(addr).DialUDP(network, addr)
}
// NextDialer returns the next dialer.
func (d *Dialer) NextDialer(dstAddr string) proxy.Dialer {
d.mu.RLock()
defer d.mu.RUnlock()
return d.nextForwarder(dstAddr)
}
// Priority returns the active priority of dialer.
func (d *Dialer) Priority() uint32 { return atomic.LoadUint32(&d.priority) }
// SetPriority sets the active priority of daler.
func (d *Dialer) SetPriority(p uint32) { atomic.StoreUint32(&d.priority, p) }
// initAvailable traverse d.fwdrs and init the available forwarder slice.
func (d *Dialer) initAvailable() {
for _, f := range d.fwdrs {
if f.Enabled() {
d.SetPriority(f.Priority())
break
}
}
d.available = nil
for _, f := range d.fwdrs {
if f.Enabled() && f.Priority() >= d.Priority() {
d.available = append(d.available, f)
}
}
if len(d.available) == 0 {
// no available forwarders, set priority to 0 to check all forwarders in check func
d.SetPriority(0)
log.F("[strategy] no available forwarders, just use: %s, please check your settings or network", d.fwdrs[0].Addr())
d.available = append(d.available, d.fwdrs[0])
}
}
// onStatusChanged will be called when fwdr's status changed.
func (d *Dialer) onStatusChanged(fwdr *proxy.Forwarder) {
d.mu.Lock()
defer d.mu.Unlock()
if fwdr.Enabled() {
log.F("[strategy] %s changed status from Disabled to Enabled ", fwdr.Addr())
if fwdr.Priority() == d.Priority() {
d.available = append(d.available, fwdr)
} else if fwdr.Priority() > d.Priority() {
d.initAvailable()
}
} else {
log.F("[strategy] %s changed status from Enabled to Disabled", fwdr.Addr())
for i, f := range d.available {
if f == fwdr {
d.available[i], d.available = d.available[len(d.available)-1], d.available[:len(d.available)-1]
break
}
}
}
if len(d.available) == 0 {
d.initAvailable()
}
}
// Check implements the Checker interface.
func (d *Dialer) Check() {
for i := 0; i < len(d.fwdrs); i++ {
go d.check(i)
}
}
func (d *Dialer) check(i int) {
f := d.fwdrs[i]
retry := 1
buf := make([]byte, 4)
for {
time.Sleep(time.Duration(d.config.CheckInterval) * time.Second * time.Duration(retry>>1))
// check all forwarders at least one time
if retry > 1 && f.Priority() < d.Priority() {
continue
}
retry <<= 1
if retry > 16 {
retry = 16
}
startTime := time.Now()
rc, err := f.Dial("tcp", d.config.CheckWebSite)
if err != nil {
f.Disable()
log.F("[check] %s(%d) -> %s, DISABLED. error in dial: %s", f.Addr(), f.Priority(), d.config.CheckWebSite, err)
continue
}
rc.Write([]byte("GET / HTTP/1.0\r\n\r\n"))
_, err = io.ReadFull(rc, buf)
if err != nil {
f.Disable()
log.F("[check] %s(%d) -> %s, DISABLED. error in read: %s", f.Addr(), f.Priority(), d.config.CheckWebSite, err)
} else if bytes.Equal([]byte("HTTP"), buf) {
readTime := time.Since(startTime)
f.SetLatency(int64(readTime))
if readTime > time.Duration(d.config.CheckTimeout)*time.Second {
f.Disable()
log.F("[check] %s(%d) -> %s, DISABLED. check timeout: %s", f.Addr(), f.Priority(), d.config.CheckWebSite, readTime)
} else {
retry = 2
f.Enable()
log.F("[check] %s(%d) -> %s, ENABLED. connect time: %s", f.Addr(), f.Priority(), d.config.CheckWebSite, readTime)
}
} else {
f.Disable()
log.F("[check] %s(%d) -> %s, DISABLED. server response: %s", f.Addr(), f.Priority(), d.config.CheckWebSite, buf)
}
rc.Close()
}
}
// Round Robin
func (d *Dialer) scheduleRR(dstAddr string) *proxy.Forwarder {
return d.available[atomic.AddUint32(&d.index, 1)%uint32(len(d.available))]
}
// High Availability
func (d *Dialer) scheduleHA(dstAddr string) *proxy.Forwarder {
return d.available[0]
}
// Latency based High Availability
func (d *Dialer) scheduleLHA(dstAddr string) *proxy.Forwarder {
fwdr := d.available[0]
lowest := fwdr.Latency()
for _, f := range d.available {
if f.Latency() < lowest {
lowest = f.Latency()
fwdr = f
}
}
return fwdr
}
// Destination Hashing
func (d *Dialer) scheduleDH(dstAddr string) *proxy.Forwarder {
fnv1a := fnv.New32a()
fnv1a.Write([]byte(dstAddr))
return d.available[fnv1a.Sum32()%uint32(len(d.available))]
}