GOCBC-1008: Convert exists error to cas mismatch for subdoc

Motivation
----------
When applicable we covert full doc DocAlreadyExists errors to
CasMismatch. We need to do the same for subdoc mutations i.e. do
the conversion when the doc level flags are not set to Add.

Changes
-------
Update the translateMemdError to convert exists error to cas mismatch
for mutatein when the operation is not a doc level Add.

Change-Id: I143b91065cc3f968675134f64eff407e8c22fe2f
Reviewed-on: http://review.couchbase.org/c/gocbcore/+/140327
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Charles Dixon <chvckd@gmail.com>

crudcomponent_subdoc_test.go

@@ -2,7 +2,7 @@ package gocbcore
 
 import (
 	"bytes"
-
+	"errors"
 	"github.com/couchbase/gocbcore/v9/memd"
 )
 
@@ -335,3 +335,66 @@ func (suite *StandardTestSuite) TestTombstones() {
 	}))
 	s.Wait(0)
 }
+
+func (suite *StandardTestSuite) TestSubdocCasMismatch() {
+	agent, s := suite.GetAgentAndHarness()
+
+	s.PushOp(agent.Set(SetOptions{
+		Key:            []byte("testSubdocCasMismatch"),
+		Value:          []byte("{\"x\":\"xattrs\", \"y\":\"yattrs\" }"),
+		CollectionName: suite.CollectionName,
+		ScopeName:      suite.ScopeName,
+	}, func(res *StoreResult, err error) {
+		s.Wrap(func() {
+			if err != nil {
+				s.Fatalf("Set operation failed: %v", err)
+			}
+		})
+	}))
+	s.Wait(0)
+
+	s.PushOp(agent.MutateIn(MutateInOptions{
+		Key: []byte("testSubdocCasMismatch"),
+		Ops: []SubDocOp{
+			{
+				Op:    memd.SubDocOpDictSet,
+				Flags: memd.SubdocFlagNone,
+				Path:  "x",
+				Value: []byte("\"x value\""),
+			},
+		},
+		CollectionName: suite.CollectionName,
+		ScopeName:      suite.ScopeName,
+		Cas:            1234,
+	}, func(res *MutateInResult, err error) {
+		s.Wrap(func() {
+			if !errors.Is(err, ErrCasMismatch) {
+				s.Fatalf("Mutate operation should have failed with Cas Mismatch but was: %v", err)
+			}
+		})
+	}))
+	s.Wait(0)
+
+	// With Add flag
+	s.PushOp(agent.MutateIn(MutateInOptions{
+		Key: []byte("testSubdocCasMismatch"),
+		Ops: []SubDocOp{
+			{
+				Op:    memd.SubDocOpDictSet,
+				Flags: memd.SubdocFlagNone,
+				Path:  "x",
+				Value: []byte("\"x value\""),
+			},
+		},
+		CollectionName: suite.CollectionName,
+		ScopeName:      suite.ScopeName,
+		Flags:          memd.SubdocDocFlagAddDoc,
+	}, func(res *MutateInResult, err error) {
+		s.Wrap(func() {
+			if !errors.Is(err, ErrDocumentExists) {
+				s.Fatalf("Mutate operation should have failed with Exists but was: %v", err)
+			}
+		})
+	}))
+	s.Wait(0)
+}

errmapcomponent.go

@@ -127,7 +127,8 @@ func translateMemdError(err error, req *memdQRequest) error {
 	case ErrMemdBusy:
 		return errTemporaryFailure
 	case ErrMemdKeyExists:
-		if req.Command == memd.CmdReplace || (req.Command == memd.CmdDelete && req.Cas != 0) {
+		if req.Command == memd.CmdReplace || (req.Command == memd.CmdDelete && req.Cas != 0) ||
+			(req.Command == memd.CmdSubDocMultiMutation && req.Cas != 0) {
 			return errCasMismatch
 		}
 		return errDocumentExists