[FAB-4106] Config update computation library

As part of FAB-1678, the configtx translator helper tool needs to be
able to take in an original config, a modified config, and compute the
config update transaction which would transition between the two.

This CR adds a small package for performing this computation, to be
leveraged by the actual tool code in FAB-1678.

Change-Id: I931d316e464dfb95589293d84ad499693ba11d4c
Signed-off-by: Jason Yellick <[email protected]>

Author: Jason Yellick

common/tools/configtxlator/update/update.go

@@ -0,0 +1,234 @@
+/*
+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 update
+
+import (
+	"fmt"
+	"reflect"
+
+	cb "github.com/hyperledger/fabric/protos/common"
+)
+
+func computePoliciesMapUpdate(original, updated map[string]*cb.ConfigPolicy) (readSet, writeSet, sameSet map[string]*cb.ConfigPolicy, updatedMembers bool) {
+	readSet = make(map[string]*cb.ConfigPolicy)
+	writeSet = make(map[string]*cb.ConfigPolicy)
+
+	// All modified config goes into the read/write sets, but in case the map membership changes, we retain the
+	// config which was the same to add to the read/write sets
+	sameSet = make(map[string]*cb.ConfigPolicy)
+
+	for policyName, originalPolicy := range original {
+		updatedPolicy, ok := updated[policyName]
+		if !ok {
+			updatedMembers = true
+			continue
+		}
+
+		if originalPolicy.ModPolicy == updatedPolicy.ModPolicy && reflect.DeepEqual(originalPolicy.Policy, updatedPolicy.Policy) {
+			sameSet[policyName] = &cb.ConfigPolicy{
+				Version: originalPolicy.Version,
+			}
+			continue
+		}
+
+		writeSet[policyName] = &cb.ConfigPolicy{
+			Version:   originalPolicy.Version + 1,
+			ModPolicy: updatedPolicy.ModPolicy,
+			Policy:    updatedPolicy.Policy,
+		}
+	}
+
+	for policyName, updatedPolicy := range updated {
+		if _, ok := original[policyName]; ok {
+			// If the updatedPolicy is in the original set of policies, it was already handled
+			continue
+		}
+		updatedMembers = true
+		writeSet[policyName] = &cb.ConfigPolicy{
+			Version:   0,
+			ModPolicy: updatedPolicy.ModPolicy,
+			Policy:    updatedPolicy.Policy,
+		}
+	}
+
+	return
+}
+
+func computeValuesMapUpdate(original, updated map[string]*cb.ConfigValue) (readSet, writeSet, sameSet map[string]*cb.ConfigValue, updatedMembers bool) {
+	readSet = make(map[string]*cb.ConfigValue)
+	writeSet = make(map[string]*cb.ConfigValue)
+
+	// All modified config goes into the read/write sets, but in case the map membership changes, we retain the
+	// config which was the same to add to the read/write sets
+	sameSet = make(map[string]*cb.ConfigValue)
+
+	for valueName, originalValue := range original {
+		updatedValue, ok := updated[valueName]
+		if !ok {
+			updatedMembers = true
+			continue
+		}
+
+		if originalValue.ModPolicy == updatedValue.ModPolicy && reflect.DeepEqual(originalValue.Value, updatedValue.Value) {
+			sameSet[valueName] = &cb.ConfigValue{
+				Version: originalValue.Version,
+			}
+			continue
+		}
+
+		writeSet[valueName] = &cb.ConfigValue{
+			Version:   originalValue.Version + 1,
+			ModPolicy: updatedValue.ModPolicy,
+			Value:     updatedValue.Value,
+		}
+	}
+
+	for valueName, updatedValue := range updated {
+		if _, ok := original[valueName]; ok {
+			// If the updatedValue is in the original set of values, it was already handled
+			continue
+		}
+		updatedMembers = true
+		writeSet[valueName] = &cb.ConfigValue{
+			Version:   0,
+			ModPolicy: updatedValue.ModPolicy,
+			Value:     updatedValue.Value,
+		}
+	}
+
+	return
+}
+
+func computeGroupsMapUpdate(original, updated map[string]*cb.ConfigGroup) (readSet, writeSet, sameSet map[string]*cb.ConfigGroup, updatedMembers bool) {
+	readSet = make(map[string]*cb.ConfigGroup)
+	writeSet = make(map[string]*cb.ConfigGroup)
+
+	// All modified config goes into the read/write sets, but in case the map membership changes, we retain the
+	// config which was the same to add to the read/write sets
+	sameSet = make(map[string]*cb.ConfigGroup)
+
+	for groupName, originalGroup := range original {
+		updatedGroup, ok := updated[groupName]
+		if !ok {
+			updatedMembers = true
+			continue
+		}
+
+		groupReadSet, groupWriteSet, groupUpdated := computeGroupUpdate(originalGroup, updatedGroup)
+		if !groupUpdated {
+			sameSet[groupName] = groupReadSet
+			continue
+		}
+
+		readSet[groupName] = groupReadSet
+		writeSet[groupName] = groupWriteSet
+
+	}
+
+	for groupName, updatedGroup := range updated {
+		if _, ok := original[groupName]; ok {
+			// If the updatedGroup is in the original set of groups, it was already handled
+			continue
+		}
+		updatedMembers = true
+		_, groupWriteSet, _ := computeGroupUpdate(cb.NewConfigGroup(), updatedGroup)
+		writeSet[groupName] = &cb.ConfigGroup{
+			Version:   0,
+			ModPolicy: updatedGroup.ModPolicy,
+			Policies:  groupWriteSet.Policies,
+			Values:    groupWriteSet.Values,
+			Groups:    groupWriteSet.Groups,
+		}
+	}
+
+	return
+}
+
+func computeGroupUpdate(original, updated *cb.ConfigGroup) (readSet, writeSet *cb.ConfigGroup, updatedGroup bool) {
+	readSetPolicies, writeSetPolicies, sameSetPolicies, policiesMembersUpdated := computePoliciesMapUpdate(original.Policies, updated.Policies)
+	readSetValues, writeSetValues, sameSetValues, valuesMembersUpdated := computeValuesMapUpdate(original.Values, updated.Values)
+	readSetGroups, writeSetGroups, sameSetGroups, groupsMembersUpdated := computeGroupsMapUpdate(original.Groups, updated.Groups)
+
+	// If the updated group is 'Equal' to the updated group (none of the members nor the mod policy changed)
+	if !(policiesMembersUpdated || valuesMembersUpdated || groupsMembersUpdated || original.ModPolicy != updated.ModPolicy) {
+
+		// If there were no modified entries in any of the policies/values/groups maps
+		if len(readSetPolicies) == 0 &&
+			len(writeSetPolicies) == 0 &&
+			len(readSetValues) == 0 &&
+			len(writeSetValues) == 0 &&
+			len(readSetGroups) == 0 &&
+			len(writeSetGroups) == 0 {
+			return &cb.ConfigGroup{
+					Version: original.Version,
+				}, &cb.ConfigGroup{
+					Version: original.Version,
+				}, false
+		}
+
+		return &cb.ConfigGroup{
+				Version:  original.Version,
+				Policies: readSetPolicies,
+				Values:   readSetValues,
+				Groups:   readSetGroups,
+			}, &cb.ConfigGroup{
+				Version:  original.Version,
+				Policies: writeSetPolicies,
+				Values:   writeSetValues,
+				Groups:   writeSetGroups,
+			}, true
+	}
+
+	for k, samePolicy := range sameSetPolicies {
+		readSetPolicies[k] = samePolicy
+		writeSetPolicies[k] = samePolicy
+	}
+
+	for k, sameValue := range sameSetValues {
+		readSetValues[k] = sameValue
+		writeSetValues[k] = sameValue
+	}
+
+	for k, sameGroup := range sameSetGroups {
+		readSetGroups[k] = sameGroup
+		writeSetGroups[k] = sameGroup
+	}
+
+	return &cb.ConfigGroup{
+			Version:  original.Version,
+			Policies: readSetPolicies,
+			Values:   readSetValues,
+			Groups:   readSetGroups,
+		}, &cb.ConfigGroup{
+			Version:   original.Version + 1,
+			Policies:  writeSetPolicies,
+			Values:    writeSetValues,
+			Groups:    writeSetGroups,
+			ModPolicy: updated.ModPolicy,
+		}, true
+}
+
+func Compute(original, updated *cb.Config) (*cb.ConfigUpdate, error) {
+	readSet, writeSet, groupUpdated := computeGroupUpdate(original.ChannelGroup, updated.ChannelGroup)
+	if !groupUpdated {
+		return nil, fmt.Errorf("no differences detected between original and updated config")
+	}
+	return &cb.ConfigUpdate{
+		ReadSet:  readSet,
+		WriteSet: writeSet,
+	}, nil
+}