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
|
/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Essentials.Sessions.VNCache
* File: WebSessionProvider.cs
*
* WebSessionProvider.cs is part of VNLib.Plugins.Essentials.Sessions.VNCache which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Essentials.Sessions.VNCache is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Plugins.Essentials.Sessions.VNCache 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 https://www.gnu.org/licenses/.
*/
using System;
using System.Threading;
using System.Threading.Tasks;
using VNLib.Net.Http;
using VNLib.Utils.Logging;
using VNLib.Plugins.Essentials;
using VNLib.Plugins.Essentials.Sessions;
using VNLib.Plugins.Extensions.Loading;
namespace VNLib.Plugins.Sessions.VNCache
{
[ServiceExport]
[ConfigurationName(WEB_SESSION_CONFIG)]
public sealed class WebSessionProvider : ISessionProvider
{
internal const string WEB_SESSION_CONFIG = "web";
internal const string LOGGER_SCOPE = "WEB-SESSIONS";
private static readonly SessionHandle _vf = new (null, FileProcessArgs.VirtualSkip, null);
private readonly WebSessionStore _sessions;
private readonly uint _maxConnections;
private uint _waitingConnections;
public WebSessionProvider(PluginBase plugin, IConfigScope config)
{
_maxConnections = config["max_waiting_connections"].GetUInt32();
//Init session provider
_sessions = plugin.GetOrCreateSingleton<WebSessionStore>();
ILogProvider logger = plugin.Log.CreateScope("WEB-SESSIONS");
logger.Information("Session provider loaded");
}
/*
* This is a dynamic method captured by the session loader to determine if the
* current session provider can process the incoming request.
*/
public bool CanProcess(IHttpEvent entity) => _sessions.IsConnected;
///<inheritdoc/>
public ValueTask<SessionHandle> GetSessionAsync(IHttpEvent entity, CancellationToken cancellationToken)
{
//Limit max number of waiting clients and make sure were connected
if (!_sessions.IsConnected || _waitingConnections > _maxConnections)
{
//Set 503 for temporary unavail
entity.CloseResponse(System.Net.HttpStatusCode.ServiceUnavailable);
return ValueTask.FromResult(_vf);
}
ValueTask<WebSession?> result = _sessions.GetSessionAsync(entity, cancellationToken);
if (result.IsCompleted)
{
WebSession? session = result.GetAwaiter().GetResult();
//Post process and get handle for session
SessionHandle handle = PostProcess(session);
return ValueTask.FromResult(handle);
}
else
{
return new(AwaitAsyncGet(result));
}
}
private SessionHandle PostProcess(WebSession? session) => session == null ? SessionHandle.Empty : new (session, OnSessionReleases);
private ValueTask OnSessionReleases(ISession session, IHttpEvent entity) => _sessions.ReleaseSessionAsync((WebSession)session, entity);
private async Task<SessionHandle> AwaitAsyncGet(ValueTask<WebSession?> async)
{
//Inct wait count while async waiting
Interlocked.Increment(ref _waitingConnections);
try
{
//await the session
WebSession? session = await async.ConfigureAwait(false);
//return empty session handle if the session could not be found
return PostProcess(session);
}
finally
{
Interlocked.Decrement(ref _waitingConnections);
}
}
}
}
|
