acceptor wrapper and rate limiting implementation (#102)

Makefile

@@ -49,6 +49,9 @@ run-cluster-worker-example-worker:
 run-custom-metrics-example:
 	@cd examples/demo/custom_metrics && go run main.go --port 3250
 
+run-rate-limiting-example:
+	@go run examples/demo/rate_limiting/main.go
+
 protos-compile:
 	@cd benchmark/testdata && ./gen_proto.sh
 	@protoc -I pitaya-protos/ pitaya-protos/*.proto --go_out=plugins=grpc:protos
@@ -139,3 +142,6 @@ test-coverage-func coverage-func: test-coverage merge-profiles
 
 serializer-mock:
 	@mockgen github.com/topfreegames/pitaya/serialize Serializer | sed 's/mock_serialize/mocks/' > serialize/mocks/serializer.go
+
+acceptor-mock:
+	@mockgen github.com/topfreegames/pitaya/acceptor Acceptor | sed 's/mock_acceptor/mocks/' > mocks/acceptor.go

acceptorwrapper/base.go

@@ -0,0 +1,69 @@
+// Copyright (c) TFG Co. All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package acceptorwrapper
+
+import (
+	"net"
+
+	"github.com/topfreegames/pitaya/acceptor"
+)
+
+// BaseWrapper implements Wrapper by saving the acceptor as an attribute.
+// Conns from acceptor.GetConnChan are processed by wrapConn and
+// forwarded to its own connChan.
+// Any new wrapper can inherit from BaseWrapper and just implement wrapConn.
+type BaseWrapper struct {
+	acceptor.Acceptor
+	connChan chan net.Conn
+	wrapConn func(net.Conn) net.Conn
+}
+
+// NewBaseWrapper returns an instance of BaseWrapper.
+func NewBaseWrapper(wrapConn func(net.Conn) net.Conn) BaseWrapper {
+	return BaseWrapper{
+		connChan: make(chan net.Conn),
+		wrapConn: wrapConn,
+	}
+}
+
+// Wrap saves acceptor as an attribute
+func (b *BaseWrapper) Wrap(a acceptor.Acceptor) acceptor.Acceptor {
+	b.Acceptor = a
+	return b
+}
+
+// ListenAndServe starts a goroutine that wraps acceptor's conn
+// and calls acceptor's listenAndServe
+func (b *BaseWrapper) ListenAndServe() {
+	go b.pipe()
+	b.Acceptor.ListenAndServe()
+}
+
+// GetConnChan returns the wrapper conn chan
+func (b *BaseWrapper) GetConnChan() chan net.Conn {
+	return b.connChan
+}
+
+func (b *BaseWrapper) pipe() {
+	for conn := range b.Acceptor.GetConnChan() {
+		b.connChan <- b.wrapConn(conn)
+	}
+}

acceptorwrapper/base_test.go

@@ -0,0 +1,74 @@
+// Copyright (c) TFG Co. All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package acceptorwrapper
+
+import (
+	"net"
+	"testing"
+
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/assert"
+	"github.com/topfreegames/pitaya/mocks"
+)
+
+func TestListenAndServe(t *testing.T) {
+	t.Parallel()
+
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	mockAcceptor := mocks.NewMockAcceptor(ctrl)
+	mockConn := mocks.NewMockConn(ctrl)
+
+	conns := make(chan net.Conn)
+	exit := make(chan struct{})
+	reads := 3
+	go func() {
+		for i := 0; i < reads; i++ {
+			mockConn.EXPECT().Read([]byte{})
+			conns <- mockConn
+		}
+	}()
+
+	mockAcceptor.EXPECT().GetConnChan().Return(conns)
+	wrapper := &BaseWrapper{
+		Acceptor: mockAcceptor,
+		connChan: make(chan net.Conn),
+		wrapConn: func(c net.Conn) net.Conn {
+			_, err := c.Read([]byte{})
+			assert.NoError(t, err)
+			return c
+		},
+	}
+
+	go func() {
+		i := 0
+		for range wrapper.GetConnChan() {
+			i++
+			if i == reads {
+				close(exit)
+			}
+		}
+	}()
+
+	mockAcceptor.EXPECT().ListenAndServe().Do(func() { <-exit })
+	wrapper.ListenAndServe()
+}

acceptorwrapper/rate_limiter.go

@@ -0,0 +1,108 @@
+// Copyright (c) TFG Co. All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package acceptorwrapper
+
+import (
+	"container/list"
+	"net"
+	"time"
+
+	"github.com/topfreegames/pitaya"
+	"github.com/topfreegames/pitaya/constants"
+	"github.com/topfreegames/pitaya/logger"
+	"github.com/topfreegames/pitaya/metrics"
+)
+
+// RateLimiter wraps net.Conn by applying rate limiting and return empty
+// if exceeded. It uses the leaky bucket
+// algorithm (https://en.wikipedia.org/wiki/Leaky_bucket).
+// Here, "limit" is the number of requests it accepts during an "interval" duration.
+// After making a request, a slot is occupied and only freed after "interval"
+// duration. If a new request comes when no slots are available, the buffer from
+// Read is droped and ignored by pitaya.
+// On the client side, this will yield a timeout error and the client must
+// be prepared to handle it.
+type RateLimiter struct {
+	net.Conn
+	limit        int
+	interval     time.Duration
+	times        list.List
+	forceDisable bool
+}
+
+// NewRateLimiter returns an initialized *RateLimiting
+func NewRateLimiter(
+	conn net.Conn,
+	limit int,
+	interval time.Duration,
+	forceDisable bool,
+) *RateLimiter {
+	r := &RateLimiter{
+		Conn:         conn,
+		limit:        limit,
+		interval:     interval,
+		forceDisable: forceDisable,
+	}
+
+	r.times.Init()
+
+	return r
+}
+
+func (r *RateLimiter) Read(b []byte) (n int, err error) {
+	if r.forceDisable {
+		return r.Conn.Read(b)
+	}
+
+	for {
+		n, err = r.Conn.Read(b)
+		if err != nil {
+			return n, err
+		}
+
+		now := time.Now()
+		if r.shouldRateLimit(now) {
+			logger.Log.Errorf("Data=%s, Error=%s", b, constants.ErrRateLimitExceeded)
+			metrics.ReportExceededRateLimiting(pitaya.GetMetricsReporters())
+			continue
+		}
+
+		return n, err
+	}
+}
+
+// shouldRateLimit saves the now as time taken or returns an error if
+// in the limit of rate limiting
+func (r *RateLimiter) shouldRateLimit(now time.Time) bool {
+	if r.times.Len() < r.limit {
+		r.times.PushBack(now)
+		return false
+	}
+
+	front := r.times.Front()
+	if diff := now.Sub(front.Value.(time.Time)); diff < r.interval {
+		return true
+	}
+
+	front.Value = now
+	r.times.MoveToBack(front)
+	return false
+}