Add NodeOverride option (#224)

Adds NodeOverride option to override the default SWIM-based gossip-style node membership protocol used for membership management.

Author: dorianperkins

.github/workflows/test.yaml

@@ -8,14 +8,12 @@ jobs:
   test:
     name: Run tests
     runs-on: ubuntu-latest    
-
     env:
       GOPATH: ${{ github.workspace }}
       GO111MODULE: off
     defaults:
       run:
         working-directory: ${{ env.GOPATH }}/src/github.com/${{ github.repository }}
-
     steps:   
     - name: Setup Go
       uses: actions/setup-go@v2

glide.lock

@@ -9,6 +9,7 @@ import:
 - package: github.com/dgryski/go-farm
 - package: github.com/rcrowley/go-metrics
 - package: github.com/stretchr/testify
+  version: 1.7.0
   subpackages:
   - assert
   - mock

glide.yaml

@@ -368,6 +368,15 @@ func RequiresAppInPing(requiresAppInPing bool) Option {
 	}
 }
 
+// NodeOverride is used to optionally override the default SWIM-based
+// gossip-style node membership protocol used for membership management.
+func NodeOverride(node swim.NodeInterface) Option {
+	return func(r *Ringpop) error {
+		r.node = node
+		return nil
+	}
+}
+
 // Default options
 
 // defaultClock sets the ringpop clock interface to use the system clock

options.go

@@ -26,12 +26,13 @@ import (
 
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/suite"
+	"github.com/uber/ringpop-go/events"
 	"github.com/uber/ringpop-go/hashring"
 	"github.com/uber/ringpop-go/logging"
 	"github.com/uber/ringpop-go/membership"
 	"github.com/uber/ringpop-go/swim"
 	"github.com/uber/ringpop-go/test/mocks"
-	"github.com/uber/ringpop-go/test/mocks/logger"
+	mocklogger "github.com/uber/ringpop-go/test/mocks/logger"
 	"github.com/uber/tchannel-go"
 )
 
@@ -345,6 +346,25 @@ func (s *RingpopOptionsTestSuite) TestSelfEvictOptions() {
 
 }
 
+// TestNodeOverride tests that the swim.NodeInterface implementation that is
+// provided to NodeOverride is correctly set on the Ringpop instance.
+func (s *RingpopOptionsTestSuite) TestNodeOverride() {
+	type mockNode struct {
+		events.SyncEventEmitter
+		mocks.SwimNode
+	}
+
+	mockNode1 := &mockNode{}
+	mockNode2 := &mockNode{}
+
+	rp, err := New("test", Channel(s.channel), NodeOverride(mockNode1))
+	s.Require().NotNil(rp)
+	s.Require().NoError(err)
+
+	s.Same(mockNode1, rp.node)
+	s.NotSame(mockNode2, rp.node)
+}
+
 func TestRingpopOptionsTestSuite(t *testing.T) {
 	suite.Run(t, new(RingpopOptionsTestSuite))
 }

options_test.go

@@ -123,7 +123,7 @@ type state uint
 
 const (
 	// created means the Ringpop instance has been created but the swim node,
-	// stats and hasring haven't been set up. The listen address has not been
+	// stats and hashring haven't been set up. The listen address has not been
 	// resolved yet either.
 	created state = iota
 	// initialized means the listen address has been resolved and the swim
@@ -190,14 +190,16 @@ func (rp *Ringpop) init() error {
 	rp.subChannel = rp.channel.GetSubChannel("ringpop", tchannel.Isolated)
 	rp.registerHandlers()
 
-	rp.node = swim.NewNode(rp.config.App, address, rp.subChannel, &swim.Options{
-		StateTimeouts:     rp.config.StateTimeouts,
-		Clock:             rp.clock,
-		LabelLimits:       rp.config.LabelLimits,
-		InitialLabels:     rp.config.InitialLabels,
-		SelfEvict:         rp.config.SelfEvict,
-		RequiresAppInPing: rp.config.RequiresAppInPing,
-	})
+	if rp.node == nil {
+		rp.node = swim.NewNode(rp.config.App, address, rp.subChannel, &swim.Options{
+			StateTimeouts:     rp.config.StateTimeouts,
+			Clock:             rp.clock,
+			LabelLimits:       rp.config.LabelLimits,
+			InitialLabels:     rp.config.InitialLabels,
+			SelfEvict:         rp.config.SelfEvict,
+			RequiresAppInPing: rp.config.RequiresAppInPing,
+		})
+	}
 	rp.node.AddListener(rp)
 
 	rp.ring = hashring.New(farm.Fingerprint32, rp.configHashRing.ReplicaPoints)