[FAB-8261] Introduce Multi Errors type

This type is used to represent multiple errors,
typically from multiple server targets invoked
by the SDK in the same operation.

Change-Id: I718478751c93e5b430b929dfd82f1d263bf864f7
Signed-off-by: Divyank Katira <Divyank.Katira@securekey.com>

api/apifabclient/proposer.go

@@ -12,7 +12,7 @@ import (
 
 // ProposalProcessor simulates transaction proposal, so that a client can submit the result for ordering.
 type ProposalProcessor interface {
-	ProcessTransactionProposal(proposal TransactionProposal) (TransactionProposalResult, error)
+	ProcessTransactionProposal(proposal TransactionProposal) (TransactionProposalResponse, error)
 }
 
 // ProposalSender provides the ability for a transaction proposal to be created and sent.
@@ -43,19 +43,11 @@ type TransactionProposal struct {
 	Proposal       *pb.Proposal
 }
 
-// TransactionProposalResponse encapsulates both the result of transaction proposal processing and errors.
+// TransactionProposalResponse respresents the result of transaction proposal processing.
 type TransactionProposalResponse struct {
-	TransactionProposalResult
-	Err error // TODO: consider refactoring
-}
-
-// TransactionProposalResult respresents the result of transaction proposal processing.
-type TransactionProposalResult struct {
 	Endorser string
 	Status   int32
 
 	Proposal         TransactionProposal
 	ProposalResponse *pb.ProposalResponse
 }
-
-// TODO: TransactionProposalResponse and TransactionProposalResult may need better names.

api/apitxn/resmgmtclient/resmgmt.go

@@ -32,7 +32,6 @@ type InstallCCResponse struct {
 	Target string
 	Status int32
 	Info   string
-	Err    error
 }
 
 // InstantiateCCRequest contains instantiate chaincode request parameters

pkg/errors/multi/multi.go

@@ -0,0 +1,72 @@
+/*
+Copyright SecureKey Technologies Inc. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package multi
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Errors is used to represent multiple errors
+type Errors []error
+
+// New Errors object with the given errors. Only non-nil errors are added.
+func New(errs ...error) error {
+	errors := Errors{}
+	for _, err := range errs {
+		if err != nil {
+			errors = append(errors, err)
+		}
+	}
+
+	if len(errors) == 0 {
+		return nil
+	}
+
+	if len(errors) == 1 {
+		return errors[0]
+	}
+
+	return errors
+}
+
+// Append error to Errors. If the first arg is not an Errors object, one will be created
+func Append(errs error, err error) error {
+	m, ok := errs.(Errors)
+	if !ok {
+		return New(errs, err)
+	}
+	return append(m, err)
+}
+
+// ToError converts Errors to the error interface
+// returns nil if no errors are present, a single error object if only one is present
+func (errs Errors) ToError() error {
+	if len(errs) == 0 {
+		return nil
+	}
+	if len(errs) == 1 {
+		return errs[0]
+	}
+	return errs
+}
+
+// Error implements the error interface to return a string representation of Errors
+func (errs Errors) Error() string {
+	if len(errs) == 0 {
+		return ""
+	}
+	if len(errs) == 1 {
+		return errs[0].Error()
+	}
+
+	errors := []string{fmt.Sprint("Multiple errors occurred: ")}
+	for _, err := range errs {
+		errors = append(errors, err.Error())
+	}
+	return strings.Join(errors, "\n")
+}

pkg/errors/multi/multi_test.go

@@ -0,0 +1,63 @@
+/*
+Copyright SecureKey Technologies Inc. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package multi
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorString(t *testing.T) {
+	testErr := fmt.Errorf("test")
+	var errs Errors
+
+	assert.Equal(t, "", errs.Error())
+
+	errs = append(errs, testErr)
+	assert.Equal(t, testErr.Error(), errs.Error())
+
+	errs = append(errs, testErr)
+	assert.Equal(t, "Multiple errors occurred: \ntest\ntest", errs.Error())
+}
+
+func TestAppend(t *testing.T) {
+	testErr := fmt.Errorf("test")
+	testErr2 := fmt.Errorf("test2")
+
+	m := Append(nil, nil)
+	assert.Nil(t, m)
+
+	m = Append(nil, testErr)
+	assert.Equal(t, testErr, m)
+
+	m = Append(testErr, testErr2)
+	m1, ok := m.(Errors)
+	assert.True(t, ok)
+	assert.Equal(t, testErr, m1[0])
+	assert.Equal(t, testErr2, m1[1])
+
+	m = Append(Errors{testErr}, testErr2)
+	m1, ok = m.(Errors)
+	assert.True(t, ok)
+	assert.Equal(t, testErr, m1[0])
+	assert.Equal(t, testErr2, m1[1])
+}
+
+func TestToError(t *testing.T) {
+	testErr := fmt.Errorf("test")
+	var errs Errors
+
+	assert.Equal(t, nil, errs.ToError())
+
+	errs = append(errs, testErr)
+	assert.Equal(t, testErr, errs.ToError())
+
+	errs = append(errs, testErr)
+	assert.Equal(t, errs, errs.ToError())
+}

pkg/errors/status/codes.go

@@ -38,6 +38,9 @@ const (
 
 	// NoPeersFound No peers were discovered/configured
 	NoPeersFound Code = 6
+
+	// MultipleErrors multiple errors occurred
+	MultipleErrors Code = 7
 )
 
 // CodeName maps the codes in this packages to human-readable strings
@@ -49,6 +52,7 @@ var CodeName = map[int32]string{
 	4: "EMPTY_CERT",
 	5: "TIMEOUT",
 	6: "NO_PEERS_FOUND",
+	7: "MULTIPLE_ERRORS",
 }
 
 // ToInt32 cast to int32

pkg/errors/status/status.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/pkg/errors"
 
+	"github.com/hyperledger/fabric-sdk-go/pkg/errors/multi"
 	pb "github.com/hyperledger/fabric-sdk-go/third_party/github.com/hyperledger/fabric/protos/peer"
 	grpcstatus "google.golang.org/grpc/status"
 )
@@ -94,8 +95,8 @@ func (g Group) String() string {
 	return UnknownStatus.String()
 }
 
-// FromError returns a Status representing err if it was produced from this
-// package, otherwise it returns nil, false.
+// FromError returns a Status representing err if available,
+// otherwise it returns nil, false.
 func FromError(err error) (s *Status, ok bool) {
 	if err == nil {
 		return &Status{Code: int32(OK)}, true
@@ -107,6 +108,9 @@ func FromError(err error) (s *Status, ok bool) {
 	if s, ok := unwrappedErr.(*Status); ok {
 		return s, true
 	}
+	if m, ok := unwrappedErr.(multi.Errors); ok {
+		return New(ClientStatus, MultipleErrors.ToInt32(), m.Error(), nil), true
+	}
 
 	return nil, false
 }

pkg/errors/status/status_test.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"testing"
 
+	"github.com/hyperledger/fabric-sdk-go/pkg/errors/multi"
 	"github.com/hyperledger/fabric-sdk-go/third_party/github.com/hyperledger/fabric/protos/common"
 	pb "github.com/hyperledger/fabric-sdk-go/third_party/github.com/hyperledger/fabric/protos/peer"
 	"github.com/pkg/errors"
@@ -65,6 +66,14 @@ func TestFromError(t *testing.T) {
 
 	s, ok = FromError(fmt.Errorf("Test"))
 	assert.False(t, ok)
+
+	errs := multi.Errors{}
+	errs = append(errs, fmt.Errorf("Test"))
+	s, ok = FromError(errs)
+	assert.True(t, ok)
+	assert.Equal(t, ClientStatus, s.Group)
+	assert.EqualValues(t, MultipleErrors.ToInt32(), s.Code)
+	assert.Equal(t, errs.Error(), s.Message)
 }
 
 func TestStatusToError(t *testing.T) {

pkg/fabric-client/channel/channel.go

@@ -431,7 +431,7 @@ func (c *Channel) QueryByChaincode(request fab.ChaincodeInvokeRequest) ([][]byte
 		return nil, err
 	}
 	resps, err := queryChaincode(c.clientContext, c.name, request, targets)
-	return filterProposalResponses(resps, err)
+	return collectProposalResponses(resps), err
 }
 
 // QueryBySystemChaincode invokes a chaincode that isn't part of a channel.
@@ -443,5 +443,5 @@ func (c *Channel) QueryBySystemChaincode(request fab.ChaincodeInvokeRequest) ([]
 		return nil, err
 	}
 	resps, err := queryChaincode(c.clientContext, systemChannel, request, targets)
-	return filterProposalResponses(resps, err)
+	return collectProposalResponses(resps), err
 }