/
Learner.java
120 lines (102 loc) · 4.87 KB
/
Learner.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
/**
* Copyright (c) 2011 Yahoo! Inc. All rights reserved.
*
* 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. See accompanying LICENSE file.
*/
package com.yahoo.pasc.paxos.handlers.learner;
import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.yahoo.pasc.Message;
import com.yahoo.pasc.paxos.handlers.PaxosHandler;
import com.yahoo.pasc.paxos.handlers.proposer.ProposerRequest;
import com.yahoo.pasc.paxos.messages.Accepted;
import com.yahoo.pasc.paxos.messages.Execute;
import com.yahoo.pasc.paxos.messages.PaxosDescriptor;
import com.yahoo.pasc.paxos.state.IidAcceptorsCounts;
import com.yahoo.pasc.paxos.state.PaxosState;
public class Learner extends PaxosHandler<Accepted> {
private static final Logger LOG = LoggerFactory.getLogger(Learner.class);
@Override
public List<PaxosDescriptor> processMessage(Accepted message, PaxosState state) {
long iid = message.getIid();
long firstInstanceId = state.getFirstInstanceId();
int maxInstances = state.getMaxInstances();
if (iid < firstInstanceId || firstInstanceId + maxInstances <= iid) {
// LOG.warn("Rejecting accepted. firstId: {} iid: {}", firstInstanceId, iid);
return null;
}
long currentBallot = state.getBallotAcceptor();
long ballot = message.getBallot();
if (ballot < currentBallot) {
LOG.warn("Rejecting accepted. msg ballot: {} current ballot: {}", ballot,
currentBallot);
return null;
}
List<PaxosDescriptor> descriptors = new ArrayList<PaxosDescriptor>();
int quorum = state.getQuorum();
int servers = state.getServers();
IidAcceptorsCounts instance = state.getAcceptedElement(iid);
boolean uninitialized = instance == null || instance.getIid() != iid;
boolean learned = instance != null && instance.isAccepted() && instance.getCardinality(servers) >= quorum;
boolean old = instance != null && instance.getBallot() < currentBallot;
if (uninitialized || (!learned && old)) {
instance = new IidAcceptorsCounts(iid, message.getBallot());
state.setAcceptedElement(iid, instance);
}
instance.setAcceptor(message.getSenderId());
checkExecute(iid, state, descriptors, null);
return descriptors;
}
public static void checkExecute(long checkIid, PaxosState state, List<PaxosDescriptor> descriptors) {
checkExecute(checkIid, state, descriptors, null);
}
public static void checkExecute(long checkIid, PaxosState state, List<PaxosDescriptor> descriptors, Accepted msg) {
// LOG.trace("Checking if instance {} is learned with message {}.", checkIid, msg);
long maxExecuted = state.getMaxExecuted();
long firstInstanceId = state.getFirstInstanceId();
int maxInstances = state.getMaxInstances();
int quorum = state.getQuorum();
int servers = state.getServers();
boolean isLeader = state.getIsLeader();
for (long iid = checkIid; iid < firstInstanceId + maxInstances; ++iid) {
// LOG.trace("Checking instance {}.", iid);
if (iid != maxExecuted + 1) {
// LOG.trace("Next instance to be executed is {} and we are at {}", maxExecuted + 1, iid);
return;
}
IidAcceptorsCounts instance = state.getAcceptedElement(iid);
if (instance == null || instance.getIid() != iid) {
return;
}
if (instance.isAccepted() && instance.getCardinality(servers) >= quorum) {
// LOG.trace("This instance has been accepted.");
if (isLeader) {
// LOG.trace("Decrement pending.");
ProposerRequest.decrementPending(state, descriptors);
}
// execute instance
// LOG.trace("Execute instance " + iid);
maxExecuted++;
state.setMaxExecuted(maxExecuted);
descriptors.add(new Execute.Descriptor(iid));
} else {
// if (instance.isAccepted())
// LOG.trace("This instance doesn't have a quorum of accepts yet.");
// else
// LOG.trace("This instance hasn't been accepted yet.");
}
}
}
}