mock adapter: Group all replies for one request under one call to MockReply

Sequence numbers are now used to match requests with replies.
Mock adapter thus has to be able to tell how many messages
from the head of the queue with mock replies belong to the currently
processed request. Then they can be given the right context and
the rest of the queued replies are postponed to be delivered later
(when context of their request is known).

All replies for one request are now therefore queued together.
This affects just multipart requests for which replies have to
be pushed all at once. The trailling control ping reply is still
queued separately, however, because that is actualy another request,
e.g.:

    mockVpp.MockReply(  // push multipart messages all at once
                      &interfaces.SwInterfaceDetails{SwIfIndex:1},
                      &interfaces.SwInterfaceDetails{SwIfIndex:2},
                      &interfaces.SwInterfaceDetails{SwIfIndex:3},
    )
    mockVpp.MockReply(&vpe.ControlPingReply{})

Even if the multipart request has no replies, MockReply has to be
called exactly twice:

    mockVpp.MockReply()  // zero multipart messages
    mockVpp.MockReply(&vpe.ControlPingReply{})

Change-Id: I28c15d2f52d14dca0b7fb06033d7270a7da2bde6
Signed-off-by: Milan Lenco <milan.lenco@pantheon.tech>

1 files changed, 78 insertions, 43 deletions

diff --git a/adapter/mock/mock_adapter.go b/adapter/mock/mock_adapter.go
index ae4caf0..959fd86 100644
--- a/adapter/mock/mock_adapter.go
+++ b/adapter/mock/mock_adapter.go
@@ -67,11 +67,19 @@ type MessageDTO struct {
 	Data     []byte
 }
 
+// reply for one request (can be multipart, contain replies to previously timeouted requests, etc.)
 type reply struct {
-	msg       api.Message
-	multipart bool
-	hasSeqNum bool
-	seqNum    uint16
+	msgs []MsgWithContext
+}
+
+// MsgWithContext encapsulates reply message with possibly sequence number and is-multipart flag.
+type MsgWithContext struct {
+	Msg       api.Message
+	SeqNum    uint16
+	Multipart bool
+
+	/* set by mock adapter */
+	hasCtx    bool
 }
 
 // ReplyHandler is a type that allows to extend the behaviour of VPP mock.
@@ -253,37 +261,32 @@ func (a *VppAdapter) SendMsg(clientID uint32, data []byte) error {
 		a.repliesLock.Lock()
 		defer a.repliesLock.Unlock()
 
-		// pop all replies from queue
-		withSeqNums := false
-		for i, reply := range a.replies {
-			if i > 0 && reply.msg.GetMessageName() == "control_ping_reply" && !withSeqNums {
-				// hack - do not send control_ping_reply immediately, leave it for the the next callback
-				a.replies = a.replies[i:]
-				return nil
-			}
-			msgID, _ := a.GetMsgID(reply.msg.GetMessageName(), reply.msg.GetCrcString())
-			buf := new(bytes.Buffer)
-			context := clientID
-			context = setMultipart(context, reply.multipart)
-			if reply.hasSeqNum {
-				withSeqNums = true
-				context = setSeqNum(context, reply.seqNum)
-			}
-			if reply.msg.GetMessageType() == api.ReplyMessage {
-				struc.Pack(buf, &core.VppReplyHeader{VlMsgID: msgID, Context: context})
-			} else if reply.msg.GetMessageType() == api.EventMessage {
-				struc.Pack(buf, &core.VppEventHeader{VlMsgID: msgID, Context: context})
-			} else if reply.msg.GetMessageType() == api.RequestMessage {
-				struc.Pack(buf, &core.VppRequestHeader{VlMsgID: msgID, Context: context})
-			} else {
-				struc.Pack(buf, &core.VppOtherHeader{VlMsgID: msgID})
-			}
-			struc.Pack(buf, reply.msg)
-			a.callback(context, msgID, buf.Bytes())
-		}
+		// pop the first reply
 		if len(a.replies) > 0 {
-			a.replies = []reply{}
-			if len(a.replyHandlers) > 0 {
+			reply := a.replies[0]
+			for _, msg := range reply.msgs {
+				msgID, _ := a.GetMsgID(msg.Msg.GetMessageName(), msg.Msg.GetCrcString())
+				buf := new(bytes.Buffer)
+				context := clientID
+				if msg.hasCtx {
+					context = setMultipart(context, msg.Multipart)
+					context = setSeqNum(context, msg.SeqNum)
+				}
+				if msg.Msg.GetMessageType() == api.ReplyMessage {
+					struc.Pack(buf, &core.VppReplyHeader{VlMsgID: msgID, Context: context})
+				} else if msg.Msg.GetMessageType() == api.EventMessage {
+					struc.Pack(buf, &core.VppEventHeader{VlMsgID: msgID, Context: context})
+				} else if msg.Msg.GetMessageType() == api.RequestMessage {
+					struc.Pack(buf, &core.VppRequestHeader{VlMsgID: msgID, Context: context})
+				} else {
+					struc.Pack(buf, &core.VppOtherHeader{VlMsgID: msgID})
+				}
+				struc.Pack(buf, msg.Msg)
+				a.callback(context, msgID, buf.Bytes())
+			}
+
+			a.replies = a.replies[1:]
+			if len(a.replies) == 0 && len(a.replyHandlers) > 0 {
 				// Switch back to handlers once the queue is empty to revert back
 				// the fallthrough effect.
 				a.mode = useReplyHandlers
@@ -313,24 +316,56 @@ func (a *VppAdapter) WaitReady() error {
 	return nil
 }
 
-// MockReply stores a message to be returned when the next request comes. It is a FIFO queue - multiple replies
-// can be pushed into it, the first one will be popped when some request comes.
-// Using of this method automatically switches the mock into th useRepliesQueue mode.
-func (a *VppAdapter) MockReply(replyMsg api.Message, isMultipart bool) {
+// MockReply stores a message or a list of multipart messages to be returned when
+// the next request comes. It is a FIFO queue - multiple replies can be pushed into it,
+// the first message or the first set of multi-part messages will be popped when
+// some request comes.
+// Using of this method automatically switches the mock into the useRepliesQueue mode.
+//
+// Note: multipart requests are implemented using two requests actually - the multipart
+// request itself followed by control ping used to tell which multipart message
+// is the last one. A mock reply to a multipart request has to thus consist of
+// exactly two calls of this method.
+// For example:
+//
+//    mockVpp.MockReply(  // push multipart messages all at once
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:1},
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:2},
+// 			&interfaces.SwInterfaceDetails{SwIfIndex:3},
+//    )
+//    mockVpp.MockReply(&vpe.ControlPingReply{})
+//
+// Even if the multipart request has no replies, MockReply has to be called twice:
+//
+//    mockVpp.MockReply()  // zero multipart messages
+//    mockVpp.MockReply(&vpe.ControlPingReply{})
+func (a *VppAdapter) MockReply(msgs ...api.Message) {
 	a.repliesLock.Lock()
 	defer a.repliesLock.Unlock()
 
-	a.replies = append(a.replies, reply{msg: replyMsg, multipart: isMultipart, hasSeqNum: false})
+	r := reply{}
+	for _, msg := range msgs {
+		r.msgs = append(r.msgs, MsgWithContext{Msg: msg, hasCtx: false})
+	}
+	a.replies = append(a.replies, r)
 	a.mode = useRepliesQueue
 }
 
-// MockReplyWithSeqNum queues next reply like MockReply() does, except that the
-// sequence number can be customized and not necessarily match with the request.
-func (a *VppAdapter) MockReplyWithSeqNum(replyMsg api.Message, isMultipart bool, sequenceNum uint16) {
+// MockReplyWithContext queues next reply like MockReply() does, except that the
+// sequence number and multipart flag (= context minus channel ID) can be customized
+// and not necessarily match with the request.
+// The purpose of this function is to test handling of sequence numbers and as such
+// it is not really meant to be used outside the govpp UTs.
+func (a *VppAdapter) MockReplyWithContext(msgs ...MsgWithContext) {
 	a.repliesLock.Lock()
 	defer a.repliesLock.Unlock()
 
-	a.replies = append(a.replies, reply{msg: replyMsg, multipart: isMultipart, hasSeqNum: true, seqNum: sequenceNum})
+	r := reply{}
+	for _, msg := range msgs {
+		r.msgs = append(r.msgs,
+			MsgWithContext{Msg: msg.Msg, SeqNum: msg.SeqNum, Multipart: msg.Multipart, hasCtx: true})
+	}
+	a.replies = append(a.replies, r)
 	a.mode = useRepliesQueue
 }