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mvcc: allow clients to assign watcher IDs #8662

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5 changes: 5 additions & 0 deletions Documentation/dev-guide/apispec/swagger/rpc.swagger.json
Original file line number Diff line number Diff line change
Expand Up @@ -2283,6 +2283,11 @@
"description": "start_revision is an optional revision to watch from (inclusive). No start_revision is \"now\".",
"type": "string",
"format": "int64"
},
"watch_id": {
"description": "If watch_id is provided, it will be used to assign to this watcher. Since\ncreating a watcher in etcd is not a synchronous operation, this can be\nused ensure that ordering is correct when creating multiple watchers on\nthe same stream. Creating a watcher with an ID already in use on the\nstream will cause an error to be returned.",
"type": "string",
"format": "int64"
}
}
},
Expand Down
1 change: 1 addition & 0 deletions etcdserver/api/v3rpc/rpctypes/error.go
Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ var (
ErrGRPCAuthNotEnabled = status.New(codes.FailedPrecondition, "etcdserver: authentication is not enabled").Err()
ErrGRPCInvalidAuthToken = status.New(codes.Unauthenticated, "etcdserver: invalid auth token").Err()
ErrGRPCInvalidAuthMgmt = status.New(codes.InvalidArgument, "etcdserver: invalid auth management").Err()
ErrGRPCDuplicateWatcherID = status.New(codes.InvalidArgument, "etcdserver: duplicate watcher ID").Err()

ErrGRPCNoLeader = status.New(codes.Unavailable, "etcdserver: no leader").Err()
ErrGRPCNotLeader = status.New(codes.FailedPrecondition, "etcdserver: not leader").Err()
Expand Down
110 changes: 59 additions & 51 deletions etcdserver/api/v3rpc/watch.go
Original file line number Diff line number Diff line change
Expand Up @@ -170,6 +170,60 @@ func (sws *serverWatchStream) isWatchPermitted(wcr *pb.WatchCreateRequest) bool
return sws.ag.AuthStore().IsRangePermitted(authInfo, wcr.Key, wcr.RangeEnd) == nil
}

func (sws *serverWatchStream) recvWatchRequest(creq *pb.WatchCreateRequest) (wr *pb.WatchResponse, id mvcc.WatchID, err error) {
if len(creq.Key) == 0 {
// \x00 is the smallest key
creq.Key = []byte{0}
}
if len(creq.RangeEnd) == 0 {
// force nil since watchstream.Watch distinguishes
// between nil and []byte{} for single key / >=
creq.RangeEnd = nil
}
if len(creq.RangeEnd) == 1 && creq.RangeEnd[0] == 0 {
// support >= key queries
creq.RangeEnd = []byte{}
}

if !sws.isWatchPermitted(creq) {
return nil, mvcc.WatchID(creq.WatchId), rpctypes.ErrGRPCPermissionDenied
}

filters := FiltersFromRequest(creq)

wsrev := sws.watchStream.Rev()
rev := creq.StartRevision
if rev == 0 {
rev = wsrev + 1
}

id, err = sws.watchStream.Watch(mvcc.WatchID(creq.WatchId), creq.Key, creq.RangeEnd, rev, filters...)
wr = &pb.WatchResponse{
Header: sws.newResponseHeader(wsrev),
WatchId: int64(id),
Created: true,
Canceled: false,
}

switch {
case err == mvcc.ErrEmptyWatcherRange:
wr.Canceled = true
case err != nil:
return nil, id, err
default:
sws.mu.Lock()
if creq.ProgressNotify {
sws.progress[id] = true
}
if creq.PrevKv {
sws.prevKV[id] = true
}
sws.mu.Unlock()
}

return wr, id, nil
}

func (sws *serverWatchStream) recvLoop() error {
for {
req, err := sws.gRPCStream.Recv()
Expand All @@ -185,66 +239,20 @@ func (sws *serverWatchStream) recvLoop() error {
if uv.CreateRequest == nil {
break
}

creq := uv.CreateRequest
if len(creq.Key) == 0 {
// \x00 is the smallest key
creq.Key = []byte{0}
}
if len(creq.RangeEnd) == 0 {
// force nil since watchstream.Watch distinguishes
// between nil and []byte{} for single key / >=
creq.RangeEnd = nil
}
if len(creq.RangeEnd) == 1 && creq.RangeEnd[0] == 0 {
// support >= key queries
creq.RangeEnd = []byte{}
}

if !sws.isWatchPermitted(creq) {
wr := &pb.WatchResponse{
wr, id, err := sws.recvWatchRequest(uv.CreateRequest)
if err != nil {
wr = &pb.WatchResponse{
Header: sws.newResponseHeader(sws.watchStream.Rev()),
WatchId: -1,
WatchId: int64(id),
Canceled: true,
Created: true,
CancelReason: rpctypes.ErrGRPCPermissionDenied.Error(),
}

select {
case sws.ctrlStream <- wr:
case <-sws.closec:
CancelReason: err.Error(),
}
return nil
}

filters := FiltersFromRequest(creq)

wsrev := sws.watchStream.Rev()
rev := creq.StartRevision
if rev == 0 {
rev = wsrev + 1
}
id := sws.watchStream.Watch(creq.Key, creq.RangeEnd, rev, filters...)
if id != -1 {
sws.mu.Lock()
if creq.ProgressNotify {
sws.progress[id] = true
}
if creq.PrevKv {
sws.prevKV[id] = true
}
sws.mu.Unlock()
}
wr := &pb.WatchResponse{
Header: sws.newResponseHeader(wsrev),
WatchId: int64(id),
Created: true,
Canceled: id == -1,
}
select {
case sws.ctrlStream <- wr:
case <-sws.closec:
return nil
}
case *pb.WatchRequest_CancelRequest:
if uv.CancelRequest != nil {
Expand Down
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