2aa18cafc6
With CoreDNS now supporting etcdv3 as the DNS backend, we can update our federation target to etcdv3. Users will now be able to use etcdv3 server as the federation backbone. Minio will update bucket data to etcdv3 and CoreDNS can pick that data up and serve it as bucket style DNS path.
118 lines
3.3 KiB
Go
118 lines
3.3 KiB
Go
// Copyright 2016 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package raft
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import pb "github.com/coreos/etcd/raft/raftpb"
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// ReadState provides state for read only query.
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// It's caller's responsibility to call ReadIndex first before getting
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// this state from ready, it's also caller's duty to differentiate if this
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// state is what it requests through RequestCtx, eg. given a unique id as
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// RequestCtx
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type ReadState struct {
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Index uint64
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RequestCtx []byte
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}
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type readIndexStatus struct {
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req pb.Message
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index uint64
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acks map[uint64]struct{}
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}
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type readOnly struct {
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option ReadOnlyOption
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pendingReadIndex map[string]*readIndexStatus
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readIndexQueue []string
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}
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func newReadOnly(option ReadOnlyOption) *readOnly {
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return &readOnly{
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option: option,
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pendingReadIndex: make(map[string]*readIndexStatus),
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}
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}
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// addRequest adds a read only reuqest into readonly struct.
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// `index` is the commit index of the raft state machine when it received
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// the read only request.
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// `m` is the original read only request message from the local or remote node.
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func (ro *readOnly) addRequest(index uint64, m pb.Message) {
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ctx := string(m.Entries[0].Data)
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if _, ok := ro.pendingReadIndex[ctx]; ok {
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return
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}
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ro.pendingReadIndex[ctx] = &readIndexStatus{index: index, req: m, acks: make(map[uint64]struct{})}
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ro.readIndexQueue = append(ro.readIndexQueue, ctx)
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}
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// recvAck notifies the readonly struct that the raft state machine received
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// an acknowledgment of the heartbeat that attached with the read only request
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// context.
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func (ro *readOnly) recvAck(m pb.Message) int {
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rs, ok := ro.pendingReadIndex[string(m.Context)]
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if !ok {
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return 0
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}
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rs.acks[m.From] = struct{}{}
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// add one to include an ack from local node
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return len(rs.acks) + 1
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}
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// advance advances the read only request queue kept by the readonly struct.
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// It dequeues the requests until it finds the read only request that has
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// the same context as the given `m`.
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func (ro *readOnly) advance(m pb.Message) []*readIndexStatus {
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var (
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i int
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found bool
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)
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ctx := string(m.Context)
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rss := []*readIndexStatus{}
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for _, okctx := range ro.readIndexQueue {
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i++
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rs, ok := ro.pendingReadIndex[okctx]
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if !ok {
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panic("cannot find corresponding read state from pending map")
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}
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rss = append(rss, rs)
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if okctx == ctx {
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found = true
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break
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}
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}
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if found {
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ro.readIndexQueue = ro.readIndexQueue[i:]
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for _, rs := range rss {
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delete(ro.pendingReadIndex, string(rs.req.Entries[0].Data))
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}
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return rss
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}
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return nil
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}
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// lastPendingRequestCtx returns the context of the last pending read only
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// request in readonly struct.
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func (ro *readOnly) lastPendingRequestCtx() string {
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if len(ro.readIndexQueue) == 0 {
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return ""
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}
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return ro.readIndexQueue[len(ro.readIndexQueue)-1]
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}
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