FAB-6099 Add support for experimental build tag

In order to support conditional compilation,
this CR adds support for an "experimental"
tag in the build system. The default is
to build with experimental features.

In order to use this, one simply adds
"// +build experimental" plus a blank line
at the top of Go source files.  This files
will only be compiled if the experimental tag
is set.

Added examples/experimental to demonstrate the
use of Go build tags

Change-Id: If9bbfc718ee1e470433c42f0447e5adb6d1c59b3
Signed-off-by: Gari Singh <gari.r.singh@gmail.com>

Author: mastersingh24

Makefile

@@ -39,6 +39,11 @@ PROJECT_NAME   = hyperledger/fabric
 BASE_VERSION = 1.1.0
 PREV_VERSION = 1.0.0
 IS_RELEASE = false
+EXPERIMENTAL ?= true
+
+ifeq ($(EXPERIMENTAL),true)
+GO_TAGS += experimental
+endif
 
 ifneq ($(IS_RELEASE),true)
 EXTRA_VERSION ?= snapshot-$(shell git rev-parse --short HEAD)
@@ -60,14 +65,15 @@ METADATA_VAR += BaseVersion=$(BASEIMAGE_RELEASE)
 METADATA_VAR += BaseDockerLabel=$(BASE_DOCKER_LABEL)
 METADATA_VAR += DockerNamespace=$(DOCKER_NS)
 METADATA_VAR += BaseDockerNamespace=$(BASE_DOCKER_NS)
+METADATA_VAR += Experimental=$(EXPERIMENTAL)
 
 GO_LDFLAGS = $(patsubst %,-X $(PKGNAME)/common/metadata.%,$(METADATA_VAR))
 
 GO_TAGS ?=
 
 CHAINTOOL_URL ?= https://nexus.hyperledger.org/content/repositories/releases/org/hyperledger/fabric/hyperledger-fabric/chaintool-$(CHAINTOOL_RELEASE)/hyperledger-fabric-chaintool-$(CHAINTOOL_RELEASE).jar
 
-export GO_LDFLAGS
+export GO_LDFLAGS GO_TAGS
 
 EXECUTABLES = go docker git curl
 K := $(foreach exec,$(EXECUTABLES),\
@@ -167,7 +173,7 @@ verify: unit-test-clean peer-docker testenv couchdb
 
 # Generates a string to the terminal suitable for manual augmentation / re-issue, useful for running tests by hand
 test-cmd:
-	@echo "go test -ldflags \"$(GO_LDFLAGS)\""
+	@echo "go test -tags \"$(GO_TAGS)\" -ldflags \"$(GO_LDFLAGS)\""
 
 docker: $(patsubst %,build/image/%/$(DUMMY), $(IMAGES))
 native: peer orderer configtxgen cryptogen configtxlator
@@ -200,7 +206,7 @@ build/docker/bin/%: $(PROJECT_FILES)
 		-v $(abspath build/docker/bin):/opt/gopath/bin \
 		-v $(abspath build/docker/$(TARGET)/pkg):/opt/gopath/pkg \
 		$(BASE_DOCKER_NS)/fabric-baseimage:$(BASE_DOCKER_TAG) \
-		go install -ldflags "$(DOCKER_GO_LDFLAGS)" $(pkgmap.$(@F))
+		go install -tags "$(GO_TAGS)" -ldflags "$(DOCKER_GO_LDFLAGS)" $(pkgmap.$(@F))
 	@touch $@
 
 build/bin:

common/metadata/metadata.go

@@ -22,3 +22,4 @@ var BaseVersion string
 var BaseDockerLabel string
 var DockerNamespace string
 var BaseDockerNamespace string
+var Experimental string

examples/experimental/experimental.go

@@ -0,0 +1,17 @@
+// +build experimental
+
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+type MyInterface interface {
+	BaseInterface
+	DoSomethingExperimental() string
+}
+
+func (m *MyType) DoSomethingExperimental() string {
+	return "did something experimental"
+}

examples/experimental/experimental_test.go

@@ -0,0 +1,24 @@
+// +build experimental
+
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExperimental(t *testing.T) {
+	m := MyType{}
+
+	something := "did something"
+	somethingExperimental := "did something experimental"
+
+	assert.Equal(t, something, m.DoSomething())
+	assert.Equal(t, somethingExperimental, m.DoSomethingExperimental())
+}

examples/experimental/interface.go

@@ -0,0 +1,10 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+type BaseInterface interface {
+	DoSomething() string
+}

examples/experimental/interface_stable.go

@@ -0,0 +1,12 @@
+// +build !experimental
+
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+type MyInterface interface {
+	BaseInterface
+}

examples/experimental/stable.go

@@ -0,0 +1,12 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+type MyType struct{}
+
+func (m *MyType) DoSomething() string {
+	return "did something"
+}

examples/experimental/stable_test.go

@@ -0,0 +1,34 @@
+// +build !experimental
+
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+package experimental
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type testIntf interface {
+	DoSomethingExperimental() string
+}
+
+func TestStable(t *testing.T) {
+	var m MyInterface
+
+	m = &MyType{}
+
+	something := "did something"
+
+	assert.Equal(t, something, m.DoSomething())
+
+	// make sure that MyType does not implement testIntf
+	_, ok := m.(testIntf)
+	if ok {
+		t.Error("MyType (stable) should not have DoSomethingExperimental method")
+	}
+}

orderer/common/metadata/metadata.go

@@ -29,7 +29,7 @@ func GetVersionInfo() string {
 		Version = "development build"
 	}
 
-	return fmt.Sprintf("%s:\n Version: %s\n Go version: %s\n OS/Arch: %s",
-		ProgramName, Version, runtime.Version(),
-		fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH))
+	return fmt.Sprintf("%s:\n Version: %s\n Go version: %s\n OS/Arch: %s\n"+
+		" Experimental features: %s\n", ProgramName, Version, runtime.Version(),
+		fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH), common.Experimental)
 }

orderer/common/metadata/metadata_test.go

@@ -24,8 +24,9 @@ func TestGetVersionInfo(t *testing.T) {
 		common.Version = "testVersion"
 	}
 
-	expected := fmt.Sprintf("%s:\n Version: %s\n Go version: %s\n OS/Arch: %s",
-		metadata.ProgramName, common.Version, runtime.Version(),
-		fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH))
+	expected := fmt.Sprintf("%s:\n Version: %s\n Go version: %s\n OS/Arch: %s\n"+
+		" Experimental features: %s\n", metadata.ProgramName, common.Version,
+		runtime.Version(), fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
+		common.Experimental)
 	assert.Equal(t, expected, metadata.GetVersionInfo())
 }