garbage collector for limits, add readme

README.md

@@ -1 +1,47 @@
-wip
+# Architeuthis ?
+
+[![CodeFactor](https://www.codefactor.io/repository/github/simon987/architeuthis/badge)](https://www.codefactor.io/repository/github/simon987/architeuthis)
+
+*NOTE: this is very WIP* 
+
+HTTP(S) proxy with integrated load-balancing, rate-limiting
+and error handling. Built for automated web scraping.
+
+* Strictly obeys configured rate-limiting for each IP & Host
+* Seamless exponential backoff retries on timeout or error HTTP codes
+* Requires no additional configuration for integration into existing programs
+
+### Typical use case
+![user_case](use_case.png)
+
+### Sample configuration
+
+```json
+{
+  "addr": "localhost:5050",
+  "proxies": [
+    {
+      "name": "squid_P0",
+      "url": "http://p0.exemple.com:8080"
+    },
+    {
+      "name": "privoxy_P1",
+      "url": "http://p1.exemple.com:8080"
+    }
+  ],
+  "hosts": {
+    "*": {
+      "every": "750ms",
+      "burst": 5,
+      "headers": {}
+    },
+    "reddit.com": {
+      "every": "2s",
+      "burst": 1,
+      "headers": {"User-Agent":  "mybot_v0.1"}
+    },
+    ...
+  }
+}
+```
+

config.go

@@ -42,7 +42,10 @@ func applyConfig(proxy *Proxy) {
 	for host, conf := range config.Hosts {
 		duration, err := time.ParseDuration(conf.Every)
 		handleErr(err)
-		proxy.Limiters.Store(host, rate.NewLimiter(rate.Every(duration), conf.Burst))
+		proxy.Limiters[host] = &ExpiringLimiter{
+			rate.NewLimiter(rate.Every(duration), conf.Burst),
+			time.Now(),
+		}
 	}
 }
 

config.json

@@ -7,7 +7,7 @@
     },
     {
       "name": "p1",
-      "url": "http://localhost:3128"
+      "url": ""
     }
   ],
   "hosts": {

gc.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"github.com/robfig/cron"
+	"github.com/sirupsen/logrus"
+	"time"
+)
+
+func (b *Balancer) setupGarbageCollector() {
+
+	const gcInterval = time.Minute * 5
+
+	gcCron := cron.New()
+	gcSchedule := cron.Every(gcInterval)
+	gcCron.Schedule(gcSchedule, cron.FuncJob(b.cleanAllExpiredLimits))
+
+	go gcCron.Run()
+
+	logrus.WithFields(logrus.Fields{
+		"every": gcInterval,
+	}).Info("Started task cleanup cron")
+}
+
+func (b *Balancer) cleanAllExpiredLimits() {
+	before := 0
+	after := 0
+	for _, p := range b.proxies {
+		before += len(p.Limiters)
+		cleanExpiredLimits(p)
+		after += len(p.Limiters)
+	}
+
+	logrus.WithFields(logrus.Fields{
+		"removed": before - after,
+	}).Info("Did limiters cleanup")
+}
+
+func cleanExpiredLimits(proxy *Proxy) {
+
+	const ttl = time.Second
+
+	limits := make(map[string]*ExpiringLimiter, 0)
+	now := time.Now()
+
+	for host, limiter := range proxy.Limiters {
+		if now.Sub(limiter.LastRead) > ttl && shouldPruneLimiter(host) {
+			logrus.WithFields(logrus.Fields{
+				"proxy":     proxy.Name,
+				"limiter":   host,
+				"last_read": now.Sub(limiter.LastRead),
+			}).Trace("Pruning limiter")
+		} else {
+			limits[host] = limiter
+		}
+	}
+
+	proxy.Limiters = limits
+}
+
+func shouldPruneLimiter(host string) bool {
+
+	// Don't remove hosts that are coming from the config
+	_, ok := config.Hosts[host]
+	return !ok
+}

main.go

@@ -10,7 +10,6 @@ import (
 	"net/url"
 	"sort"
 	"strings"
-	"sync"
 	"time"
 )
 
@@ -19,10 +18,15 @@ type Balancer struct {
 	proxies []*Proxy
 }
 
+type ExpiringLimiter struct {
+	Limiter  *rate.Limiter
+	LastRead time.Time
+}
+
 type Proxy struct {
 	Name        string
 	Url         *url.URL
-	Limiters    sync.Map
+	Limiters    map[string]*ExpiringLimiter
 	HttpClient  *http.Client
 	Connections int
 }
@@ -41,33 +45,33 @@ func (a ByConnectionCount) Less(i, j int) bool {
 	return a[i].Connections < a[j].Connections
 }
 
-func LogRequestMiddleware(h goproxy.FuncReqHandler) goproxy.ReqHandler {
-	return goproxy.FuncReqHandler(func(r *http.Request, ctx *goproxy.ProxyCtx) (*http.Request, *http.Response) {
-
-		logrus.WithFields(logrus.Fields{
-			"host": r.Host,
-		}).Trace(strings.ToUpper(r.URL.Scheme) + " " + r.Method)
-
-		return h(r, ctx)
-	})
-}
-
-//TODO: expiration ?
 func (p *Proxy) getLimiter(host string) *rate.Limiter {
 
-	limiter, ok := p.Limiters.Load(host)
+	expLimit, ok := p.Limiters[host]
 	if !ok {
-
-		every, _ := time.ParseDuration("1ms")
-		limiter = rate.NewLimiter(rate.Every(every), 1)
-		p.Limiters.Store(host, limiter)
-
-		logrus.WithFields(logrus.Fields{
-			"host": host,
-		}).Trace("New limiter")
+		newExpiringLimiter := p.makeNewLimiter(host)
+		return newExpiringLimiter.Limiter
 	}
 
-	return limiter.(*rate.Limiter)
+	expLimit.LastRead = time.Now()
+	return expLimit.Limiter
+}
+
+func (p *Proxy) makeNewLimiter(host string) *ExpiringLimiter {
+	every := time.Millisecond //todo load default from conf
+
+	newExpiringLimiter := &ExpiringLimiter{
+		LastRead: time.Now(),
+		Limiter:  rate.NewLimiter(rate.Every(every), 1),
+	}
+
+	p.Limiters[host] = newExpiringLimiter
+
+	logrus.WithFields(logrus.Fields{
+		"host": host,
+	}).Trace("New limiter")
+
+	return newExpiringLimiter
 }
 
 func simplifyHost(host string) string {
@@ -92,7 +96,7 @@ func New() *Balancer {
 
 	balancer.server.OnRequest().HandleConnect(goproxy.AlwaysMitm)
 
-	balancer.server.OnRequest().Do(LogRequestMiddleware(
+	balancer.server.OnRequest().DoFunc(
 		func(r *http.Request, ctx *goproxy.ProxyCtx) (*http.Request, *http.Response) {
 
 			p := balancer.chooseProxy()
@@ -110,7 +114,7 @@ func New() *Balancer {
 			}
 
 			return nil, resp
-		}))
+		})
 	return balancer
 }
 
@@ -234,6 +238,7 @@ func NewProxy(name, stringUrl string) (*Proxy, error) {
 		Name:       name,
 		Url:        parsedUrl,
 		HttpClient: httpClient,
+		Limiters:   make(map[string]*ExpiringLimiter),
 	}, nil
 }
 
@@ -256,5 +261,6 @@ func main() {
 		}).Info("Proxy")
 	}
 
+	balancer.setupGarbageCollector()
 	balancer.Run()
 }

test/web.py

@@ -17,6 +17,7 @@ def e500():
 
 @app.route("/404")
 def e404():
+    time.sleep(0.5)
     return Response(status=404)