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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/base/status.h"
#include "mongo/stdx/functional.h"
#include "mongo/transport/session.h"
#include "mongo/transport/ticket.h"
#include "mongo/util/net/message.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace transport {
class TicketImpl;
/**
* The TransportLayer moves Messages between transport::Endpoints and the database.
* This class owns an Acceptor that generates new endpoints from which it can
* source Messages.
*
* The TransportLayer creates Session objects and maps them internally to
* endpoints. New Sessions are passed to the database (via a ServiceEntryPoint)
* to be run. The database must then call additional methods on the TransportLayer
* to manage the Session in a get-Message, handle-Message, return-Message cycle.
* It must do this on its own thread(s).
*
* References to the TransportLayer should be stored on service context objects.
*/
class TransportLayer {
MONGO_DISALLOW_COPYING(TransportLayer);
public:
static const Status SessionUnknownStatus;
static const Status ShutdownStatus;
static const Status TicketSessionUnknownStatus;
static const Status TicketSessionClosedStatus;
friend class Session;
/**
* Stats for sessions open in the Transport Layer.
*/
struct Stats {
/**
* Returns the number of sessions currently open in the transport layer.
*/
size_t numOpenSessions = 0;
/**
* Returns the total number of sessions that have ever been created by this TransportLayer.
*/
size_t numCreatedSessions = 0;
/**
* Returns the number of available sessions we could still open. Only relevant
* when we are operating under a transport::Session limit (for example, in the
* legacy implementation, we respect a maximum number of connections). If there
* is no session limit, returns std::numeric_limits<int>::max().
*/
size_t numAvailableSessions = 0;
};
virtual ~TransportLayer() = default;
/**
* Source (receive) a new Message for this Session.
*
* This method returns a work Ticket. The caller must complete the Ticket by
* passing it to either TransportLayer::wait() or TransportLayer::asyncWait().
*
* If an expiration date is given, the returned Ticket will expire at that time.
*
* When run, the returned Ticket will be exchanged for a Status. If the
* TransportLayer is unable to source a Message, this will be a failed status,
* and the passed-in Message buffer may be left in an invalid state.
*/
virtual Ticket sourceMessage(Session& session,
Message* message,
Date_t expiration = Ticket::kNoExpirationDate) = 0;
/**
* Sink (send) a new Message for this Session. This method should be used
* to send replies to a given host.
*
* This method returns a work Ticket. The caller must complete the Ticket by
* passing it to either TransportLayer::wait() or TransportLayer::asyncWait().
*
* If an expiration date is given, the returned Ticket will expire at that time.
*
* When run, the returned Ticket will be exchanged for a Status. If the
* TransportLayer is unable to sink the Message, this will be a failed status.
*
* This method does NOT take ownership of the sunk Message, which must be cleaned
* up by the caller.
*/
virtual Ticket sinkMessage(Session& session,
const Message& message,
Date_t expiration = Ticket::kNoExpirationDate) = 0;
/**
* Perform a synchronous wait on the given work Ticket. When this call returns,
* the Ticket will have been completed. A call to wait() consumes the Ticket.
*
* This thread may be used by the TransportLayer to run other Tickets that were
* enqueued prior to this call.
*/
virtual Status wait(Ticket&& ticket) = 0;
/**
* Callback for Tickets that are run via asyncWait().
*/
using TicketCallback = stdx::function<void(Status)>;
/**
* Perform an asynchronous wait on the given work Ticket. Once the Ticket has been
* completed, the passed-in callback will be invoked.
*
* This thread will not be used by the TransportLayer to perform work. The callback
* passed to asyncWait() may be run on any thread.
*/
virtual void asyncWait(Ticket&& ticket, TicketCallback callback) = 0;
/**
* Tag this Session within the TransportLayer with the tags currently assigned to the
* Session. If endAllSessions() is called with a matching
* Session::TagMask, this Session will not be ended.
*
* Before calling this method, use Session::replaceTags() to set the desired TagMask.
*/
virtual void registerTags(const Session& session) = 0;
/**
* Return the stored X509 peer information for this session. If the session does not
* exist in this TransportLayer, returns a default constructed object.
*/
virtual SSLPeerInfo getX509PeerInfo(const Session& session) const = 0;
/**
* Returns the number of sessions currently open in the transport layer.
*/
virtual Stats sessionStats() = 0;
/**
* End the given Session. Tickets for this Session that have already been
* started via wait() or asyncWait() will complete, but may return a failed Status.
* Future calls to wait() or asyncWait() for this Session will fail. If this
* TransportLayer implementation is networked, any connections for this Session will
* be closed.
*
* ~Session() will automatically call end() with itself.
*
* This method is idempotent and synchronous.
*/
virtual void end(Session& session) = 0;
/**
* End all active sessions in the TransportLayer. Tickets that have already been started via
* wait() or asyncWait() will complete, but may return a failed Status. This method is
* asynchronous and will return after all sessions have been notified to end.
*
* If a non-empty TagMask is provided, endAllSessions() will skip over sessions with matching
* tags and leave them open.
*/
virtual void endAllSessions(Session::TagMask tags) = 0;
/**
* Start the TransportLayer. After this point, the TransportLayer will begin accepting active
* sessions from new transport::Endpoints.
*/
virtual Status start() = 0;
/**
* Shut the TransportLayer down. After this point, the TransportLayer will
* end all active sessions and won't accept new transport::Endpoints. Any
* future calls to wait() or asyncWait() will fail. This method is synchronous and
* will not return until all sessions have ended and any network connections have been
* closed.
*/
virtual void shutdown() = 0;
protected:
TransportLayer() = default;
/**
* Return the implementation of this Ticket.
*/
TicketImpl* getTicketImpl(const Ticket& ticket) {
return ticket.impl();
}
/**
* Return the transport layer of this Ticket.
*/
TransportLayer* getTicketTransportLayer(const Ticket& ticket) {
return ticket._tl;
}
private:
/**
* Destroys any information linked to this Session in the TransportLayer.
* This should only be called from within Session's destructor.
*/
virtual void _destroy(Session& session) = 0;
};
} // namespace transport
} // namespace mongo
|
