Move diff to helper/diff, helper/resource knows about it

builtin/providers/aws/diff.go

@@ -1,32 +0,0 @@
-package aws
-
-import (
-	"github.com/hashicorp/terraform/diff"
-)
-
-var diffMap *diff.LazyResourceMap
-
-func init() {
-	diffMap = &diff.LazyResourceMap{
-		Resources: map[string]diff.ResourceBuilderFactory{
-			"aws_instance": diffBuilder_aws_instance,
-		},
-	}
-}
-
-func diffBuilder_aws_instance() *diff.ResourceBuilder {
-	return &diff.ResourceBuilder{
-		CreateComputedAttrs: []string{
-			"public_dns",
-			"public_ip",
-			"private_dns",
-			"private_ip",
-		},
-
-		RequiresNewAttrs: []string{
-			"ami",
-			"availability_zone",
-			"instance_type",
-		},
-	}
-}

builtin/providers/aws/resource_provider.go

@@ -1,7 +1,6 @@
 package aws
 
 import (
-	"fmt"
 	"log"
 
 	"github.com/hashicorp/terraform/helper/config"
@@ -60,12 +59,7 @@ func (p *ResourceProvider) Apply(
 func (p *ResourceProvider) Diff(
 	s *terraform.ResourceState,
 	c *terraform.ResourceConfig) (*terraform.ResourceDiff, error) {
-	b := diffMap.Get(s.Type)
-	if b == nil {
-		return nil, fmt.Errorf("Unknown type: %s", s.Type)
-	}
-
-	return b.Diff(s, c)
+	return resourceMap.Diff(s, c, p)
 }
 
 func (p *ResourceProvider) Refresh(

builtin/providers/aws/resources.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 
+	"github.com/hashicorp/terraform/helper/diff"
 	"github.com/hashicorp/terraform/helper/resource"
 	"github.com/hashicorp/terraform/terraform"
 	"github.com/mitchellh/goamz/ec2"
@@ -19,6 +20,7 @@ func init() {
 			"aws_instance": resource.Resource{
 				Create:  resource_aws_instance_create,
 				Destroy: resource_aws_instance_destroy,
+				Diff:    resource_aws_instance_diff,
 				Refresh: resource_aws_instance_refresh,
 			},
 		},
@@ -101,6 +103,28 @@ func resource_aws_instance_destroy(
 	return nil
 }
 
+func resource_aws_instance_diff(
+	s *terraform.ResourceState,
+	c *terraform.ResourceConfig,
+	meta interface{}) (*terraform.ResourceDiff, error) {
+	b := &diff.ResourceBuilder{
+		CreateComputedAttrs: []string{
+			"public_dns",
+			"public_ip",
+			"private_dns",
+			"private_ip",
+		},
+
+		RequiresNewAttrs: []string{
+			"ami",
+			"availability_zone",
+			"instance_type",
+		},
+	}
+
+	return b.Diff(s, c)
+}
+
 func resource_aws_instance_refresh(
 	s *terraform.ResourceState,
 	meta interface{}) (*terraform.ResourceState, error) {

diff/lazy_resource_map.go

@@ -1,51 +0,0 @@
-package diff
-
-import (
-	"sync"
-)
-
-// LazyResourceMap is a way to lazy-load resource builders.
-//
-// By lazy loading resource builders, a considerable amount of compute
-// effort for building the builders can be avoided. This is especially
-// helpful in Terraform providers that support many resource types.
-type LazyResourceMap struct {
-	Resources map[string]ResourceBuilderFactory
-
-	l        sync.Mutex
-	memoized map[string]*ResourceBuilder
-}
-
-// ResourceBuilderFactory is a factory function for creating a resource
-// builder that is used for lazy loading resource builders in the Builder
-// struct.
-type ResourceBuilderFactory func() *ResourceBuilder
-
-// Get gets the ResourceBuilder for the given resource type, and returns
-// nil if the resource builder cannot be found.
-//
-// This will memoize the result, returning the same result for the same
-// type if called again.
-func (m *LazyResourceMap) Get(r string) *ResourceBuilder {
-	m.l.Lock()
-	defer m.l.Unlock()
-
-	// If we have it saved, return that
-	if rb, ok := m.memoized[r]; ok {
-		return rb
-	}
-
-	// Get the factory function
-	f, ok := m.Resources[r]
-	if !ok {
-		return nil
-	}
-
-	// Save it so that we don't rebuild
-	if m.memoized == nil {
-		m.memoized = make(map[string]*ResourceBuilder)
-	}
-	m.memoized[r] = f()
-
-	return m.memoized[r]
-}

diff/lazy_resource_map_test.go

@@ -1,45 +0,0 @@
-package diff
-
-import (
-	"testing"
-)
-
-func TestLazyResourceMap(t *testing.T) {
-	rb1 := new(ResourceBuilder)
-	rb2 := new(ResourceBuilder)
-
-	rm := &LazyResourceMap{
-		Resources: map[string]ResourceBuilderFactory{
-			"foo": testRBFactory(rb1),
-			"bar": testRBFactory(rb2),
-			"diff": func() *ResourceBuilder {
-				return new(ResourceBuilder)
-			},
-		},
-	}
-
-	actual := rm.Get("foo")
-	if actual == nil {
-		t.Fatal("should not be nil")
-	}
-	if actual != rb1 {
-		t.Fatalf("bad: %p %p", rb1, actual)
-	}
-	if actual == rm.Get("bar") {
-		t.Fatalf("bad: %p %p", actual, rm.Get("bar"))
-	}
-
-	actual = rm.Get("diff")
-	if actual == nil {
-		t.Fatal("should not be nil")
-	}
-	if actual != rm.Get("diff") {
-		t.Fatal("should memoize")
-	}
-}
-
-func testRBFactory(rb *ResourceBuilder) ResourceBuilderFactory {
-	return func() *ResourceBuilder {
-		return rb
-	}
-}

helper/resource/map.go

@@ -31,6 +31,19 @@ func (m *Map) Apply(
 	}
 }
 
+// Diff peforms a diff on the proper resource type.
+func (m *Map) Diff(
+	s *terraform.ResourceState,
+	c *terraform.ResourceConfig,
+	meta interface{}) (*terraform.ResourceDiff, error) {
+	r, ok := m.Mapping[s.Type]
+	if !ok {
+		return nil, fmt.Errorf("Unknown resource type: %s", s.Type)
+	}
+
+	return r.Diff(s, c, meta)
+}
+
 // Refresh performs a Refresh on the proper resource type.
 //
 // Refresh on the Resource won't be called if the state represents a