[FAB-2142] Make new config comparable

https://jira.hyperledger.org/browse/FAB-2142

The new configuration structure needs to be comparable in order to
validate which portions of the incoming configuration have changed.
This CR adds a set of utilities to do just that.

Change-Id: I061288145e7d4ae257568043d152c087f1796957
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/configtx/compare.go

@@ -0,0 +1,171 @@
+/*
+Copyright IBM Corp. 2017 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+                 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package configtx
+
+import (
+	"bytes"
+
+	cb "github.com/hyperledger/fabric/protos/common"
+)
+
+type comparable struct {
+	*cb.ConfigGroup
+	*cb.ConfigValue
+	*cb.ConfigPolicy
+}
+
+func (cg comparable) equals(other comparable) bool {
+	switch {
+	case cg.ConfigGroup != nil:
+		if other.ConfigGroup == nil {
+			return false
+		}
+		return equalConfigGroup(cg.ConfigGroup, other.ConfigGroup)
+	case cg.ConfigValue != nil:
+		if other.ConfigValue == nil {
+			return false
+		}
+		return equalConfigValues(cg.ConfigValue, other.ConfigValue)
+	case cg.ConfigPolicy != nil:
+		if other.ConfigPolicy == nil {
+			return false
+		}
+		return equalConfigPolicies(cg.ConfigPolicy, other.ConfigPolicy)
+	}
+
+	// Unreachable
+	return false
+}
+
+func equalConfigValues(lhs, rhs *cb.ConfigValue) bool {
+	return lhs.Version == rhs.Version &&
+		lhs.ModPolicy == rhs.ModPolicy &&
+		bytes.Equal(lhs.Value, rhs.Value)
+}
+
+func equalConfigPolicies(lhs, rhs *cb.ConfigPolicy) bool {
+	if lhs.Version != rhs.Version ||
+		lhs.ModPolicy != rhs.ModPolicy {
+		return false
+	}
+
+	if lhs.Policy == nil || rhs.Policy == nil {
+		return lhs.Policy == rhs.Policy
+	}
+
+	return lhs.Policy.Type == rhs.Policy.Type &&
+		bytes.Equal(lhs.Policy.Policy, rhs.Policy.Policy)
+}
+
+// The subset functions check if inner is a subset of outer
+// TODO, try to consolidate these three methods into one, as the code
+// contents are the same, but the function signatures need to be different
+func subsetOfGroups(inner, outer map[string]*cb.ConfigGroup) bool {
+	// The empty set is a subset of all sets
+	if len(inner) == 0 {
+		return true
+	}
+
+	// If inner is not the empty set, then the outer empty set cannot be a superset of inner
+	if len(outer) == 0 {
+		return false
+	}
+
+	// If any element in inner is not in outer, it is not a subset
+	for key := range inner {
+		if _, ok := outer[key]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
+func subsetOfPolicies(inner, outer map[string]*cb.ConfigPolicy) bool {
+	// The empty set is a subset of all sets
+	if len(inner) == 0 {
+		return true
+	}
+
+	// If inner is not the empty set, then the outer empty set cannot be a superset of inner
+	if len(outer) == 0 {
+		return false
+	}
+
+	// If any element in inner is not in outer, it is not a subset
+	for key := range inner {
+		if _, ok := outer[key]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
+func subsetOfValues(inner, outer map[string]*cb.ConfigValue) bool {
+	// The empty set is a subset of all sets
+	if len(inner) == 0 {
+		return true
+	}
+
+	// If inner is not the empty set, then the outer empty set cannot be a superset of inner
+	if len(outer) == 0 {
+		return false
+	}
+
+	// If any element in inner is not in outer, it is not a subset
+	for key := range inner {
+		if _, ok := outer[key]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
+func equalConfigGroup(lhs, rhs *cb.ConfigGroup) bool {
+	if lhs.Version != rhs.Version ||
+		lhs.ModPolicy != rhs.ModPolicy {
+		return false
+	}
+
+	if !subsetOfGroups(lhs.Groups, rhs.Groups) {
+		return false
+	}
+
+	if !subsetOfGroups(rhs.Groups, lhs.Groups) {
+		return false
+	}
+
+	if !subsetOfPolicies(lhs.Policies, rhs.Policies) {
+		return false
+	}
+
+	if !subsetOfPolicies(rhs.Policies, lhs.Policies) {
+		return false
+	}
+
+	if !subsetOfValues(lhs.Values, rhs.Values) {
+		return false
+	}
+
+	if !subsetOfValues(rhs.Values, lhs.Values) {
+		return false
+	}
+
+	return true
+}