[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/coreos/etcd/raft/read_only.go b/vendor/github.com/coreos/etcd/raft/read_only.go
new file mode 100644
index 0000000..ae746fa
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/raft/read_only.go
@@ -0,0 +1,118 @@
+// Copyright 2016 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package raft
+
+import pb "github.com/coreos/etcd/raft/raftpb"
+
+// ReadState provides state for read only query.
+// It's caller's responsibility to call ReadIndex first before getting
+// this state from ready, it's also caller's duty to differentiate if this
+// state is what it requests through RequestCtx, eg. given a unique id as
+// RequestCtx
+type ReadState struct {
+ Index uint64
+ RequestCtx []byte
+}
+
+type readIndexStatus struct {
+ req pb.Message
+ index uint64
+ acks map[uint64]struct{}
+}
+
+type readOnly struct {
+ option ReadOnlyOption
+ pendingReadIndex map[string]*readIndexStatus
+ readIndexQueue []string
+}
+
+func newReadOnly(option ReadOnlyOption) *readOnly {
+ return &readOnly{
+ option: option,
+ pendingReadIndex: make(map[string]*readIndexStatus),
+ }
+}
+
+// addRequest adds a read only reuqest into readonly struct.
+// `index` is the commit index of the raft state machine when it received
+// the read only request.
+// `m` is the original read only request message from the local or remote node.
+func (ro *readOnly) addRequest(index uint64, m pb.Message) {
+ ctx := string(m.Entries[0].Data)
+ if _, ok := ro.pendingReadIndex[ctx]; ok {
+ return
+ }
+ ro.pendingReadIndex[ctx] = &readIndexStatus{index: index, req: m, acks: make(map[uint64]struct{})}
+ ro.readIndexQueue = append(ro.readIndexQueue, ctx)
+}
+
+// recvAck notifies the readonly struct that the raft state machine received
+// an acknowledgment of the heartbeat that attached with the read only request
+// context.
+func (ro *readOnly) recvAck(m pb.Message) int {
+ rs, ok := ro.pendingReadIndex[string(m.Context)]
+ if !ok {
+ return 0
+ }
+
+ rs.acks[m.From] = struct{}{}
+ // add one to include an ack from local node
+ return len(rs.acks) + 1
+}
+
+// advance advances the read only request queue kept by the readonly struct.
+// It dequeues the requests until it finds the read only request that has
+// the same context as the given `m`.
+func (ro *readOnly) advance(m pb.Message) []*readIndexStatus {
+ var (
+ i int
+ found bool
+ )
+
+ ctx := string(m.Context)
+ rss := []*readIndexStatus{}
+
+ for _, okctx := range ro.readIndexQueue {
+ i++
+ rs, ok := ro.pendingReadIndex[okctx]
+ if !ok {
+ panic("cannot find corresponding read state from pending map")
+ }
+ rss = append(rss, rs)
+ if okctx == ctx {
+ found = true
+ break
+ }
+ }
+
+ if found {
+ ro.readIndexQueue = ro.readIndexQueue[i:]
+ for _, rs := range rss {
+ delete(ro.pendingReadIndex, string(rs.req.Entries[0].Data))
+ }
+ return rss
+ }
+
+ return nil
+}
+
+// lastPendingRequestCtx returns the context of the last pending read only
+// request in readonly struct.
+func (ro *readOnly) lastPendingRequestCtx() string {
+ if len(ro.readIndexQueue) == 0 {
+ return ""
+ }
+ return ro.readIndexQueue[len(ro.readIndexQueue)-1]
+}