Clean up code and rename PipeRequest to PipeUpstream

Author: Jacob Wirth

CHANGELOG.md

@@ -1,6 +1,6 @@
 # 2.2.0 (unreleased)
 
-* Add bidirectional toxics #132
+* Add support for bidirectional toxics (for protocol-aware toxics) #132
 
 # 2.1.3
 

CREATING_TOXICS.md

@@ -152,7 +152,7 @@ Bidirectional toxics allow state to be shared for the `upstream` and `downstream
 toxic implementation. They also ensure direction-specific code is always run on the correct pipe
 (a toxic that only works on the `upstream` can't be added to the `downstream`).
 
-Creating a bidirectional toxic is done by implementing a second `Pipe()` function called `PipeRequest()`.
+Creating a bidirectional toxic is done by implementing a second `Pipe()` function called `PipeUpstream()`.
 The implementation is same as a regular toxic, and can be paired with other types such as a stateful toxic.
 
 One use case of a bidirectional toxic is to mock out the backend server entirely, which is shown below:
@@ -164,8 +164,8 @@ type EchoToxicState struct {
     Request          chan *stream.StreamChunk
 }
 
-// PipeRequest handles the upstream direction
-func (t *EchoToxic) PipeRequest(stub *toxics.ToxicStub) {
+// PipeUpstream handles the upstream direction
+func (t *EchoToxic) PipeUpstream(stub *toxics.ToxicStub) {
     state := stub.State.(*EchoToxicState)
 
     for {

link.go

@@ -67,14 +67,7 @@ func (link *ToxicLink) Start(name string, source io.Reader, dest io.WriteCloser)
 		link.input.Close()
 	}()
 	for i, toxic := range link.toxics.chain[link.direction] {
-		if stateful, ok := toxic.Toxic.(toxics.StatefulToxic); ok {
-			if toxic.PairedToxic == nil || link.pairedLink.stubs[toxic.PairedToxic.Index].State == nil {
-				link.stubs[i].State = stateful.NewState()
-			} else {
-				link.stubs[i].State = link.pairedLink.stubs[toxic.PairedToxic.Index].State
-				link.stubs[i].Toxicity = link.pairedLink.stubs[toxic.PairedToxic.Index].Toxicity
-			}
-		}
+		link.InitPairState(toxic)
 
 		go link.stubs[i].Run(toxic)
 	}
@@ -93,6 +86,22 @@ func (link *ToxicLink) Start(name string, source io.Reader, dest io.WriteCloser)
 	}()
 }
 
+func (link *ToxicLink) InitPairState(toxic *toxics.ToxicWrapper) {
+	// If the toxic is stateful, create a state object or copy it from the paired link.
+	if stateful, ok := toxic.Toxic.(toxics.StatefulToxic); ok {
+		if toxic.PairedToxic == nil || link.pairedLink.stubs[toxic.PairedToxic.Index].State == nil {
+			link.stubs[toxic.Index].State = stateful.NewState()
+		} else {
+			link.stubs[toxic.Index].State = link.pairedLink.stubs[toxic.PairedToxic.Index].State
+		}
+	}
+
+	// If the toxic is paired, synchronize the toxicity so they are always in the same state.
+	if toxic.PairedToxic != nil {
+		link.stubs[toxic.Index].Toxicity = link.pairedLink.stubs[toxic.PairedToxic.Index].Toxicity
+	}
+}
+
 // Add a toxic to the end of the chain.
 func (link *ToxicLink) AddToxic(toxic *toxics.ToxicWrapper) {
 	i := len(link.stubs)
@@ -104,14 +113,7 @@ func (link *ToxicLink) AddToxic(toxic *toxics.ToxicWrapper) {
 	if link.stubs[i-1].InterruptToxic() {
 		link.stubs[i-1].Output = newin
 
-		if stateful, ok := toxic.Toxic.(toxics.StatefulToxic); ok {
-			if toxic.PairedToxic == nil || link.pairedLink.stubs[toxic.PairedToxic.Index].State == nil {
-				link.stubs[i].State = stateful.NewState()
-			} else {
-				link.stubs[i].State = link.pairedLink.stubs[toxic.PairedToxic.Index].State
-				link.stubs[i].Toxicity = link.pairedLink.stubs[toxic.PairedToxic.Index].Toxicity
-			}
-		}
+		link.InitPairState(toxic)
 
 		go link.stubs[i].Run(toxic)
 		go link.stubs[i-1].Run(link.toxics.chain[link.direction][i-1])

toxics/bidirectional_test.go

@@ -23,7 +23,7 @@ type EchoToxicState struct {
 	UpstreamToxicity float32
 }
 
-func (t *EchoToxic) PipeRequest(stub *toxics.ToxicStub) {
+func (t *EchoToxic) PipeUpstream(stub *toxics.ToxicStub) {
 	state := stub.State.(*EchoToxicState)
 	state.UpstreamToxicity = stub.Toxicity
 

toxics/toxic.go

@@ -46,10 +46,10 @@ type StatefulToxic interface {
 }
 
 // Bidirectional toxics operate on both TCP streams and allow state to be shared.
-// PipeRequest() will oparate on the upstream, while Pipe() will operate on the downstream.
+// PipeUpstream() will oparate on the upstream, while Pipe() will operate on the downstream.
 type BidirectionalToxic interface {
 	// Defines the packet flow through an upstream ToxicStub. Operates the same as Pipe().
-	PipeRequest(*ToxicStub)
+	PipeUpstream(*ToxicStub)
 }
 
 type ToxicWrapper struct {
@@ -95,7 +95,7 @@ func (s *ToxicStub) Run(toxic *ToxicWrapper) {
 			toxic.Pipe(s)
 		} else {
 			bidirectional := toxic.Toxic.(BidirectionalToxic)
-			bidirectional.PipeRequest(s)
+			bidirectional.PipeUpstream(s)
 		}
 	} else {
 		new(NoopToxic).Pipe(s)