blob: 83c69b7d25d9c42380dad3f029aa9c6c52ee954a (
plain)
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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*
*/
using System;
using System.Threading;
using log4net;
using Apache.Qpid.Client.Protocol;
using Apache.Qpid.Client.State;
namespace Apache.Qpid.Client.Failover
{
public class FailoverHandler
{
private static readonly ILog _log = LogManager.GetLogger(typeof(FailoverHandler));
private AMQConnection _connection;
/**
* Used where forcing the failover host
*/
private String _host;
/**
* Used where forcing the failover port
*/
private int _port;
public FailoverHandler(AMQConnection connection)
{
_connection = connection;
}
public void Run()
{
if (Thread.CurrentThread.IsBackground)
{
throw new InvalidOperationException("FailoverHandler must Run on a non-background thread.");
}
AMQProtocolListener pl = _connection.ProtocolListener;
pl.FailoverLatch = new ManualResetEvent(false);
// We wake up listeners. If they can handle failover, they will extend the
// FailoverSupport class and will in turn block on the latch until failover
// has completed before retrying the operation
_connection.ProtocolListener.PropagateExceptionToWaiters(new FailoverException("Failing over about to start"));
// Since failover impacts several structures we protect them all with a single mutex. These structures
// are also in child objects of the connection. This allows us to manipulate them without affecting
// client code which runs in a separate thread.
lock (_connection.FailoverMutex)
{
_log.Info("Starting failover process");
// We switch in a new state manager temporarily so that the interaction to get to the "connection open"
// state works, without us having to terminate any existing "state waiters". We could theoretically
// have a state waiter waiting until the connection is closed for some reason. Or in future we may have
// a slightly more complex state model therefore I felt it was worthwhile doing this.
AMQStateManager existingStateManager = _connection.ProtocolListener.StateManager;
_connection.ProtocolListener.StateManager = new AMQStateManager();
if (!_connection.FirePreFailover(_host != null))
{
_connection.ProtocolListener.StateManager = existingStateManager;
if (_host != null)
{
_connection.ExceptionReceived(new AMQDisconnectedException("Redirect was vetoed by client"));
}
else
{
_connection.ExceptionReceived(new AMQDisconnectedException("Failover was vetoed by client"));
}
pl.FailoverLatch.Set();
pl.FailoverLatch = null;
return;
}
bool failoverSucceeded;
// when host is non null we have a specified failover host otherwise we all the client to cycle through
// all specified hosts
// if _host has value then we are performing a redirect.
if (_host != null)
{
// todo: fix SSL support!
failoverSucceeded = _connection.AttemptReconnection(_host, _port, null);
}
else
{
failoverSucceeded = _connection.AttemptReconnection();
}
// XXX: at this point it appears that we are going to set StateManager to existingStateManager in
// XXX: both paths of control.
if (!failoverSucceeded)
{
_connection.ProtocolListener.StateManager = existingStateManager;
_connection.ExceptionReceived(
new AMQDisconnectedException("Server closed connection and no failover " +
"was successful"));
}
else
{
_connection.ProtocolListener.StateManager = existingStateManager;
try
{
if (_connection.FirePreResubscribe())
{
_log.Info("Resubscribing on new connection");
_connection.ResubscribeChannels();
}
else
{
_log.Info("Client vetoed automatic resubscription");
}
_connection.FireFailoverComplete();
_connection.ProtocolListener.FailoverState = FailoverState.NOT_STARTED;
_log.Info("Connection failover completed successfully");
}
catch (Exception e)
{
_log.Info("Failover process failed - exception being propagated by protocol handler");
_connection.ProtocolListener.FailoverState = FailoverState.FAILED;
try
{
_connection.ProtocolListener.OnException(e);
}
catch (Exception ex)
{
_log.Error("Error notifying protocol session of error: " + ex, ex);
}
}
}
}
pl.FailoverLatch.Set();
}
public String getHost()
{
return _host;
}
public void setHost(String host)
{
_host = host;
}
public int getPort()
{
return _port;
}
public void setPort(int port)
{
_port = port;
}
}
}
|
