Generated handlers: Reduce is ReduceOutput

README.md

@@ -64,7 +64,7 @@ message ProvisionMachine {
 
 `protoc-gen-durable` turns that into one interface, `ProvisionMachineHandlers`:
 a method per step, `Unwind<Step>` for each step that unwinds, and
-`Reduce` for the output. One type implements the pipeline, so its
+`ReduceOutput` for the output. One type implements the pipeline, so its
 dependencies are declared once, and a step it lacks — a step added to
 the proto included — is a compile error naming the method:
 
@@ -106,7 +106,7 @@ func (h *handlers) CreateMachine(ctx context.Context, inv machinespb.ProvisionMa
     return &machinespb.ProvisionMachine_CreateMachine{MachineId: id}, nil
 }
 
-func (h *handlers) Reduce(p *machinespb.ProvisionMachine) *machinespb.ProvisionMachineOutput {
+func (h *handlers) ReduceOutput(p *machinespb.ProvisionMachine) *machinespb.ProvisionMachineOutput {
     m, _ := p.State(machinespb.ProvisionMachine_CreateMachineStep)
     return &machinespb.ProvisionMachineOutput{MachineId: m.GetMachineId()}
 }

cmd/protoc-gen-durable/internal/gen/gen.go

@@ -162,7 +162,7 @@ func Generate(p *protogen.Plugin) error {
 			methods[method] = by
 		}
 		if pl.output != nil {
-			claim("Reduce", "the output reducer")
+			claim("ReduceOutput", "the output reducer")
 		}
 		if pl.failureOutput != nil {
 			claim("ReduceFailure", "the failure reducer")
@@ -278,7 +278,7 @@ func emitPipeline(g *protogen.GeneratedFile, pl *pipelineDecl) {
 	emitInvocationAlias(g, pl)
 	emitHandlers(g, pl)
 	if pl.output != nil {
-		emitReduceHelper(g, pl, "", pl.output)
+		emitReduceHelper(g, pl, "Output", pl.output)
 	}
 	if pl.failureOutput != nil {
 		emitReduceHelper(g, pl, "Failure", pl.failureOutput)
@@ -387,10 +387,10 @@ func emitHandlers(g *protogen.GeneratedFile, pl *pipelineDecl) {
 		}
 	}
 	if pl.output != nil {
-		g.P("// Reduce produces the pipeline output from the immutable input and")
+		g.P("// ReduceOutput produces the pipeline output from the immutable input and")
 		g.P("// committed step states on success. It must be pure: deterministic,")
 		g.P("// side-effect free, synchronous, and non-failing.")
-		g.P("Reduce(*", g.QualifiedGoIdent(pl.msg.GoIdent), ") *", g.QualifiedGoIdent(pl.output.GoIdent))
+		g.P("ReduceOutput(*", g.QualifiedGoIdent(pl.msg.GoIdent), ") *", g.QualifiedGoIdent(pl.output.GoIdent))
 	}
 	if pl.failureOutput != nil {
 		g.P("// ReduceFailure produces the pipeline failure output from the immutable")
@@ -403,7 +403,7 @@ func emitHandlers(g *protogen.GeneratedFile, pl *pipelineDecl) {
 	_ = name
 }
 
-// emitReduceHelper emits Reduce<Pipeline>[Failure](h, view): the fold the
+// emitReduceHelper emits Reduce<Pipeline>Output/Failure(h, view): the fold the
 // engine reduces through and a reducer unit test calls with a
 // durabletest.NewInvocation (which is also a durable.ReduceView).
 func emitReduceHelper(g *protogen.GeneratedFile, pl *pipelineDecl, kind string, out *protogen.Message) {
@@ -500,7 +500,7 @@ func emitDefinition(g *protogen.GeneratedFile, pl *pipelineDecl) {
 	}
 	if pl.output != nil {
 		g.P("Reduce: func(view ", g.QualifiedGoIdent(durablePkg.Ident("ReduceView")), ") ", protoMsg, " {")
-		g.P("return Reduce", name, "(h, view)")
+		g.P("return Reduce", name, "Output(h, view)")
 		g.P("},")
 	}
 	if pl.failureOutput != nil {

docs/tour.md

@@ -91,7 +91,7 @@ eng := engine.New(st)
 deploy, err := deploypb.NewDeployService(&deployer{db: db, lb: lb}).Bind(eng)
 // deployer has a method per step — ProvisionEnv, RunMigrations,
 // ShiftTraffic — plus UnwindProvisionEnv, UnwindRunMigrations, and
-// Reduce; a step it lacks is a compile error.
+// ReduceOutput; a step it lacks is a compile error.
 // bind every pipeline, then:
 eng.Start(ctx)
 

durabletest/doc.go

@@ -2,6 +2,6 @@
 // fake Clock for the engine's time, and a fake Invocation (NewInvocation)
 // for unit-testing handlers without an engine or a store. Generated code
 // accepts the fake through its NewXxxInvocation constructors and folds it
-// as a reducer view through XxxReducer.Reduce. The in-memory store lives
+// as a reducer view through the generated ReduceXxxOutput. The in-memory store lives
 // in store/mem: it is a real driver, not a test double.
 package durabletest

examples/machines/handlers.go

@@ -110,7 +110,7 @@ func (h *handlers) CreateMachine(ctx context.Context, inv machinespb.ProvisionMa
 	return &machinespb.ProvisionMachine_CreateMachine{MachineId: h.cloud.id("machine")}, nil
 }
 
-func (h *handlers) Reduce(p *machinespb.ProvisionMachine) *machinespb.ProvisionMachineOutput {
+func (h *handlers) ReduceOutput(p *machinespb.ProvisionMachine) *machinespb.ProvisionMachineOutput {
 	machine, ok := p.State(machinespb.ProvisionMachine_CreateMachineStep)
 	if !ok {
 		panic("successful pipeline missing create-machine state")

examples/release-train/deploy.go

@@ -57,6 +57,6 @@ func (h *deploy) ShiftTraffic(ctx context.Context, inv releasepb.DeployServiceIn
 	return &releasepb.DeployService_ShiftTraffic{LbGeneration: inv.Input().GetImage()}, nil
 }
 
-func (h *deploy) Reduce(d *releasepb.DeployService) *releasepb.DeployServiceOutput {
+func (h *deploy) ReduceOutput(d *releasepb.DeployService) *releasepb.DeployServiceOutput {
 	return &releasepb.DeployServiceOutput{Url: "https://" + d.Input().GetService() + ".example.com"}
 }

examples/release-train/legacy.go

@@ -46,6 +46,6 @@ func (h *legacyDeploy) ShiftTraffic(ctx context.Context, inv legacypb.DeployServ
 	return &legacypb.DeployService_ShiftTraffic{LbGeneration: inv.Input().GetImage()}, nil
 }
 
-func (h *legacyDeploy) Reduce(d *legacypb.DeployService) *legacypb.DeployServiceOutput {
+func (h *legacyDeploy) ReduceOutput(d *legacypb.DeployService) *legacypb.DeployServiceOutput {
 	return &legacypb.DeployServiceOutput{Url: "https://" + d.Input().GetService() + ".example.com"}
 }

examples/snapshots/main.go

@@ -167,7 +167,7 @@ func (h *snapshotter) RegisterSnapshot(ctx context.Context, inv snapshotspb.Crea
 	return &snapshotspb.CreateSnapshot_RegisterSnapshot{SnapshotId: id}, nil
 }
 
-func (h *snapshotter) Reduce(p *snapshotspb.CreateSnapshot) *snapshotspb.CreateSnapshotOutput {
+func (h *snapshotter) ReduceOutput(p *snapshotspb.CreateSnapshot) *snapshotspb.CreateSnapshotOutput {
 	reg, _ := p.State(snapshotspb.CreateSnapshot_RegisterSnapshotStep)
 	up, _ := p.State(snapshotspb.CreateSnapshot_UploadSnapshotStep)
 	return &snapshotspb.CreateSnapshotOutput{SnapshotId: reg.GetSnapshotId(), ObjectKey: up.GetObjectKey()}

examples/snapshots/main_test.go

@@ -96,7 +96,7 @@ func TestSnapshotUnwindsOnCatalogFull(t *testing.T) {
 }
 
 // The closures are unit-testable without an engine: the generated
-// NewXxxInvocation wraps the durabletest fake, and XxxReducer.Reduce
+// NewXxxInvocation wraps the durabletest fake, and ReduceXxxOutput
 // folds it as a reducer view.
 
 func TestUploadUnwindDeletesObject(t *testing.T) {
@@ -153,7 +153,7 @@ func TestReduceCreateSnapshot(t *testing.T) {
 			snapshotspb.CreateSnapshot_RegisterSnapshotStep.ID(): &snapshotspb.CreateSnapshot_RegisterSnapshot{SnapshotId: "snap-1"},
 		},
 	})
-	out := snapshotspb.ReduceCreateSnapshot(&snapshotter{}, view)
+	out := snapshotspb.ReduceCreateSnapshotOutput(&snapshotter{}, view)
 	if out.GetSnapshotId() != "snap-1" || out.GetObjectKey() != "k" {
 		t.Fatalf("Reduce = %+v", out)
 	}

examples/tracing-otel/main.go

@@ -105,7 +105,7 @@ func (h *fulfillment) Ship(ctx context.Context, inv orderspb.FulfillOrderInvocat
 		durable.WithUserKind(), durable.WithReason("invalid-address"))
 }
 
-func (h *fulfillment) Reduce(o *orderspb.FulfillOrder) *orderspb.FulfillOrderOutput {
+func (h *fulfillment) ReduceOutput(o *orderspb.FulfillOrder) *orderspb.FulfillOrderOutput {
 	s, _ := o.State(orderspb.FulfillOrder_ShipStep)
 	return &orderspb.FulfillOrderOutput{ShipmentId: s.GetShipmentId()}
 }

spec/02-authoring.md

@@ -259,7 +259,7 @@ type ProvisionMachineHandlers interface {
     ReserveCapacity(context.Context, ProvisionMachineInvocation) (*ReserveCapacity, error)
     UnwindReserveCapacity(context.Context, ProvisionMachineInvocation) error
 
-    Reduce(*ProvisionMachine) *ProvisionMachineOutput
+    ReduceOutput(*ProvisionMachine) *ProvisionMachineOutput
 }
 
 func NewProvisionMachine(h ProvisionMachineHandlers) *ProvisionMachineDefinition
@@ -317,7 +317,7 @@ annotations, park memory) that satisfies both `durable.Invocation` and
 would invalidate the Run for. Generated code wraps it the same way it
 wraps the Engine's: `NewProvisionMachineInvocation(fake)` is what a
 `ProvisionMachineHandlers` method takes, and
-`ReduceProvisionMachine(h, fake)` folds the reducer over it.
+`ReduceProvisionMachineOutput(h, fake)` folds the reducer over it.
 
 ```go
 inv := durabletest.NewInvocation(durabletest.InvocationConfig{

spec/05-codegen.md

@@ -51,10 +51,10 @@ Published protobuf extensions MUST use globally allocated extension numbers.
   (`durable.NoInput` for an Input-less pipeline), with a
   `NewXxxInvocation(core)` constructor for engine-free handler tests,
 - one handler interface, `XxxHandlers`: a method per Step named after
-  the Step, `Unwind<Step>` for each Step that unwinds, and `Reduce` /
+  the Step, `Unwind<Step>` for each Step that unwinds, and `ReduceOutput` /
   `ReduceFailure` when the pipeline declares outputs,
 - the Pipeline constructor, `NewXxx(h XxxHandlers)`,
-- `ReduceXxx(h, view)` and `ReduceXxxFailure(h, view)`, the folds the
+- `ReduceXxxOutput(h, view)` and `ReduceXxxFailure(h, view)`, the folds the
   engine reduces through and reducer tests call,
 - runtime methods on the Pipeline marker type,
 - the bound Pipeline handle,
@@ -97,7 +97,7 @@ Generated APIs MUST make these compile-time errors where possible:
 - a missing Step method, a Step added to the pipeline included,
 - a wrong method signature,
 - a missing `Unwind<Step>`,
-- an invalid `Reduce` signature,
+- an invalid `ReduceOutput` or `ReduceFailure` signature,
 - passing a stateless `StepRef` to `State`.
 
 Generation MUST also reject a pipeline whose Step and reducer method