Girish Gowdra | 6450343 | 2020-01-07 10:59:10 +0530 | [diff] [blame] | 1 | // Copyright 2019 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package quorum |
| 16 | |
| 17 | // JointConfig is a configuration of two groups of (possibly overlapping) |
| 18 | // majority configurations. Decisions require the support of both majorities. |
| 19 | type JointConfig [2]MajorityConfig |
| 20 | |
| 21 | func (c JointConfig) String() string { |
| 22 | if len(c[1]) > 0 { |
| 23 | return c[0].String() + "&&" + c[1].String() |
| 24 | } |
| 25 | return c[0].String() |
| 26 | } |
| 27 | |
| 28 | // IDs returns a newly initialized map representing the set of voters present |
| 29 | // in the joint configuration. |
| 30 | func (c JointConfig) IDs() map[uint64]struct{} { |
| 31 | m := map[uint64]struct{}{} |
| 32 | for _, cc := range c { |
| 33 | for id := range cc { |
| 34 | m[id] = struct{}{} |
| 35 | } |
| 36 | } |
| 37 | return m |
| 38 | } |
| 39 | |
| 40 | // Describe returns a (multi-line) representation of the commit indexes for the |
| 41 | // given lookuper. |
| 42 | func (c JointConfig) Describe(l AckedIndexer) string { |
| 43 | return MajorityConfig(c.IDs()).Describe(l) |
| 44 | } |
| 45 | |
| 46 | // CommittedIndex returns the largest committed index for the given joint |
| 47 | // quorum. An index is jointly committed if it is committed in both constituent |
| 48 | // majorities. |
| 49 | func (c JointConfig) CommittedIndex(l AckedIndexer) Index { |
| 50 | idx0 := c[0].CommittedIndex(l) |
| 51 | idx1 := c[1].CommittedIndex(l) |
| 52 | if idx0 < idx1 { |
| 53 | return idx0 |
| 54 | } |
| 55 | return idx1 |
| 56 | } |
| 57 | |
| 58 | // VoteResult takes a mapping of voters to yes/no (true/false) votes and returns |
| 59 | // a result indicating whether the vote is pending, lost, or won. A joint quorum |
| 60 | // requires both majority quorums to vote in favor. |
| 61 | func (c JointConfig) VoteResult(votes map[uint64]bool) VoteResult { |
| 62 | r1 := c[0].VoteResult(votes) |
| 63 | r2 := c[1].VoteResult(votes) |
| 64 | |
| 65 | if r1 == r2 { |
| 66 | // If they agree, return the agreed state. |
| 67 | return r1 |
| 68 | } |
| 69 | if r1 == VoteLost || r2 == VoteLost { |
| 70 | // If either config has lost, loss is the only possible outcome. |
| 71 | return VoteLost |
| 72 | } |
| 73 | // One side won, the other one is pending, so the whole outcome is. |
| 74 | return VotePending |
| 75 | } |