"errors"
"fmt"
"time"
+
+ "github.com/sirupsen/logrus"
)
// MessageType represents the type of a VPP message.
RequestMessage MessageType = iota
// ReplyMessage represents a VPP reply message
ReplyMessage
+ // EventMessage represents a VPP notification event message
+ EventMessage
// OtherMessage represents other VPP message (e.g. counters)
OtherMessage
)
-// Message is an interface that is implemented by all VPP Binary API messages generated by the binapi_generator.
+// Message is an interface that is implemented by all VPP Binary API messages generated by the binapigenerator.
type Message interface {
// GetMessageName returns the original VPP name of the message, as defined in the VPP API.
GetMessageName() string
// It uses default buffer sizes for the request and reply Go channels.
NewAPIChannel() (*Channel, error)
- // NewAPIChannel returns a new channel for communication with VPP via govpp core.
+ // NewAPIChannelBuffered returns a new channel for communication with VPP via govpp core.
// It allows to specify custom buffer sizes for the request and reply Go channels.
NewAPIChannelBuffered() (*Channel, error)
}
type MessageIdentifier interface {
// GetMessageID returns message identifier of given API message.
GetMessageID(msg Message) (uint16, error)
+ // LookupByID looks up message name and crc by ID
+ LookupByID(ID uint16) (string, error)
}
// Channel is the main communication interface with govpp core. It contains two Go channels, one for sending the requests
// to VPP and one for receiving the replies from it. The user can access the Go channels directly, or use the helper
-// methods provided inside of this package.
+// methods provided inside of this package. Do not use the same channel from multiple goroutines concurrently,
+// otherwise the responses could mix! Use multiple channels instead.
type Channel struct {
+ ID uint16 // channel ID
+
ReqChan chan *VppRequest // channel for sending the requests to VPP, closing this channel releases all resources in the ChannelProvider
ReplyChan chan *VppReply // channel where VPP replies are delivered to
MsgDecoder MessageDecoder // used to decode binary data to generated API messages
MsgIdentifier MessageIdentifier // used to retrieve message ID of a message
+ lastSeqNum uint16 // sequence number of the last sent request
+
+ delayedReply *VppReply // reply already taken from ReplyChan, buffered for later delivery
replyTimeout time.Duration // maximum time that the API waits for a reply from VPP before returning an error, can be set with SetReplyTimeout
- metadata interface{} // opaque metadata of the API channel
}
// VppRequest is a request that will be sent to VPP.
type VppRequest struct {
+ SeqNum uint16 // sequence number
Message Message // binary API message to be send to VPP
Multipart bool // true if multipart response is expected, false otherwise
}
// VppReply is a reply received from VPP.
type VppReply struct {
MessageID uint16 // ID of the message
+ SeqNum uint16 // sequence number
Data []byte // encoded data with the message - MessageDecoder can be used for decoding
LastReplyReceived bool // in case of multipart replies, true if the last reply has been already received and this one should be ignored
Error error // in case of error, data is nil and this member contains error description
// RequestCtx is a context of a ongoing request (simple one - only one response is expected).
type RequestCtx struct {
ch *Channel
+ seqNum uint16
}
// MultiRequestCtx is a context of a ongoing multipart request (multiple responses are expected).
type MultiRequestCtx struct {
ch *Channel
+ seqNum uint16
}
const defaultReplyTimeout = time.Second * 1 // default timeout for replies from VPP, can be changed with SetReplyTimeout
-// NewChannelInternal returns a new channel structure with metadata field filled in with the provided argument.
+// NewChannelInternal returns a new channel structure.
// Note that this is just a raw channel not yet connected to VPP, it is not intended to be used directly.
// Use ChannelProvider to get an API channel ready for communication with VPP.
-func NewChannelInternal(metadata interface{}) *Channel {
+func NewChannelInternal(id uint16) *Channel {
return &Channel{
+ ID: id,
replyTimeout: defaultReplyTimeout,
- metadata: metadata,
}
}
-// Metadata returns the metadata stored within the channel structure by the NewChannelInternal call.
-func (ch *Channel) Metadata() interface{} {
- return ch.metadata
-}
-
// SetReplyTimeout sets the timeout for replies from VPP. It represents the maximum time the API waits for a reply
// from VPP before returning an error.
func (ch *Channel) SetReplyTimeout(timeout time.Duration) {
// SendRequest asynchronously sends a request to VPP. Returns a request context, that can be used to call ReceiveReply.
// In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
func (ch *Channel) SendRequest(msg Message) *RequestCtx {
+ ch.lastSeqNum++
ch.ReqChan <- &VppRequest{
Message: msg,
+ SeqNum: ch.lastSeqNum,
}
- return &RequestCtx{ch: ch}
+ return &RequestCtx{ch: ch, seqNum: ch.lastSeqNum}
}
// ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
return errors.New("invalid request context")
}
- lastReplyReceived, err := req.ch.receiveReplyInternal(msg)
+ lastReplyReceived, err := req.ch.receiveReplyInternal(msg, req.seqNum)
if lastReplyReceived {
err = errors.New("multipart reply recieved while a simple reply expected")
// Returns a multipart request context, that can be used to call ReceiveReply.
// In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
func (ch *Channel) SendMultiRequest(msg Message) *MultiRequestCtx {
+ ch.lastSeqNum++
ch.ReqChan <- &VppRequest{
Message: msg,
Multipart: true,
+ SeqNum: ch.lastSeqNum,
}
- return &MultiRequestCtx{ch: ch}
+ return &MultiRequestCtx{ch: ch, seqNum: ch.lastSeqNum}
}
// ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
-// The reply will be decoded into the msg argument. If the last reply has been already consumed, LastReplyReceived is
-// set to true. Do not use the message itself if LastReplyReceived is true - it won't be filled with actual data.
+// The reply will be decoded into the msg argument. If the last reply has been already consumed, lastReplyReceived is
+// set to true. Do not use the message itself if lastReplyReceived is true - it won't be filled with actual data.
// Error will be returned if the response cannot be received or decoded.
-func (req *MultiRequestCtx) ReceiveReply(msg Message) (LastReplyReceived bool, err error) {
+func (req *MultiRequestCtx) ReceiveReply(msg Message) (lastReplyReceived bool, err error) {
if req == nil || req.ch == nil {
return false, errors.New("invalid request context")
}
- return req.ch.receiveReplyInternal(msg)
+ return req.ch.receiveReplyInternal(msg, req.seqNum)
}
// receiveReplyInternal receives a reply from the reply channel into the provided msg structure.
-func (ch *Channel) receiveReplyInternal(msg Message) (LastReplyReceived bool, err error) {
+func (ch *Channel) receiveReplyInternal(msg Message, expSeqNum uint16) (lastReplyReceived bool, err error) {
+ var ignore bool
if msg == nil {
return false, errors.New("nil message passed in")
}
- select {
- // blocks until a reply comes to ReplyChan or until timeout expires
- case vppReply := <-ch.ReplyChan:
- if vppReply.Error != nil {
- err = vppReply.Error
- return
- }
- if vppReply.LastReplyReceived {
- LastReplyReceived = true
- return
+
+ if ch.delayedReply != nil {
+ // try the delayed reply
+ vppReply := ch.delayedReply
+ ch.delayedReply = nil
+ ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
+ if !ignore {
+ return lastReplyReceived, err
}
- // message checks
- expMsgID, err := ch.MsgIdentifier.GetMessageID(msg)
- if err != nil {
- err = fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
- msg.GetMessageName(), msg.GetCrcString())
+ }
+
+ timer := time.NewTimer(ch.replyTimeout)
+ for {
+ select {
+ // blocks until a reply comes to ReplyChan or until timeout expires
+ case vppReply := <-ch.ReplyChan:
+ ignore, lastReplyReceived, err = ch.processReply(vppReply, expSeqNum, msg)
+ if ignore {
+ continue
+ }
+ return lastReplyReceived, err
+
+ case <-timer.C:
+ err = fmt.Errorf("no reply received within the timeout period %s", ch.replyTimeout)
return false, err
}
- if vppReply.MessageID != expMsgID {
- err = fmt.Errorf("invalid message ID %d, expected %d", vppReply.MessageID, expMsgID)
- return false, err
+ }
+ return
+}
+
+func (ch *Channel) processReply(reply *VppReply, expSeqNum uint16, msg Message) (ignore bool, lastReplyReceived bool, err error) {
+ // check the sequence number
+ cmpSeqNums := compareSeqNumbers(reply.SeqNum, expSeqNum)
+ if cmpSeqNums == -1 {
+ // reply received too late, ignore the message
+ logrus.WithField("sequence-number", reply.SeqNum).Warn(
+ "Received reply to an already closed binary API request")
+ ignore = true
+ return
+ }
+ if cmpSeqNums == 1 {
+ ch.delayedReply = reply
+ err = fmt.Errorf("missing binary API reply with sequence number: %d", expSeqNum)
+ return
+ }
+
+ if reply.Error != nil {
+ err = reply.Error
+ return
+ }
+ if reply.LastReplyReceived {
+ lastReplyReceived = true
+ return
+ }
+
+ // message checks
+ var expMsgID uint16
+ expMsgID, err = ch.MsgIdentifier.GetMessageID(msg)
+ if err != nil {
+ err = fmt.Errorf("message %s with CRC %s is not compatible with the VPP we are connected to",
+ msg.GetMessageName(), msg.GetCrcString())
+ return
+ }
+
+ if reply.MessageID != expMsgID {
+ var msgNameCrc string
+ if nameCrc, err := ch.MsgIdentifier.LookupByID(reply.MessageID); err != nil {
+ msgNameCrc = err.Error()
+ } else {
+ msgNameCrc = nameCrc
}
- // decode the message
- err = ch.MsgDecoder.DecodeMsg(vppReply.Data, msg)
- case <-time.After(ch.replyTimeout):
- err = fmt.Errorf("no reply received within the timeout period %ds", ch.replyTimeout/time.Second)
+ err = fmt.Errorf("received invalid message ID (seq-num=%d), expected %d (%s), but got %d (%s) " +
+ "(check if multiple goroutines are not sharing single GoVPP channel)",
+ reply.SeqNum, expMsgID, msg.GetMessageName(), reply.MessageID, msgNameCrc)
+ return
}
+
+ // decode the message
+ err = ch.MsgDecoder.DecodeMsg(reply.Data, msg)
return
}
+// compareSeqNumbers returns -1, 0, 1 if sequence number <seqNum1> precedes, equals to,
+// or succeeds seq. number <seqNum2>.
+// Since sequence numbers cycle in the finite set of size 2^16, the function
+// must assume that the distance between compared sequence numbers is less than
+// (2^16)/2 to determine the order.
+func compareSeqNumbers(seqNum1, seqNum2 uint16) int {
+ // calculate distance from seqNum1 to seqNum2
+ var dist uint16
+ if seqNum1 <= seqNum2 {
+ dist = seqNum2 - seqNum1
+ } else {
+ dist = 0xffff - (seqNum1 - seqNum2 - 1)
+ }
+ if dist == 0 {
+ return 0
+ } else if dist <= 0x8000 {
+ return -1
+ }
+ return 1
+}
+
// SubscribeNotification subscribes for receiving of the specified notification messages via provided Go channel.
// Note that the caller is responsible for creating the Go channel with preferred buffer size. If the channel's
// buffer is full, the notifications will not be delivered into it.
Code Review / govpp.git / blobdiff