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.Extensions.VNCache
* File: VNCacheExtensions.cs
*
* VNCacheExtensions.cs is part of VNLib.Plugins.Extensions.VNCache which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Extensions.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.Extensions.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.Runtime.CompilerServices;
using VNLib.Hashing;
using VNLib.Utils.Memory;
using VNLib.Utils.Extensions;
using VNLib.Data.Caching;
using VNLib.Plugins.Extensions.VNCache.DataModel;
namespace VNLib.Plugins.Extensions.VNCache
{
/// <summary>
/// Contains extension methods for aquiring a Plugin managed
/// global cache provider.
/// </summary>
public static class VNCacheExtensions
{
internal const string CACHE_CONFIG_KEY = "vncache";
internal const string MEMORY_CACHE_CONFIG_KEY = "memory_cache";
internal const string MEMORY_CACHE_ONLY_KEY = "memory_only";
/// <summary>
/// Gets a simple scoped cache based on an entity prefix. The prefix is appended
/// to the object id on each cache operation
/// </summary>
/// <param name="cache"></param>
/// <param name="prefix">The simple prefix string to append to object ids before computing hashes</param>
/// <param name="digest">The algorithm used to hash the combined object-ids</param>
/// <param name="encoding">The string encoding method used to encode the hash output</param>
/// <returns>The <see cref="ScopedCache"/> instance that will use the prefix to compute object ids</returns>
/// <exception cref="ArgumentNullException"></exception>
public static ScopedCache GetPrefixedCache(this IGlobalCacheProvider cache, string prefix, HashAlg digest = HashAlg.SHA1, HashEncodingMode encoding = HashEncodingMode.Base64)
{
_ = cache ?? throw new ArgumentNullException(nameof(cache));
_ = prefix ?? throw new ArgumentNullException(nameof(prefix));
//Create simple cache key generator
SimpleCacheKeyImpl keyProv = new(prefix, digest, encoding);
//Create the scoped cache from the simple provider
return cache.GetScopedCache(keyProv);
}
private sealed class SimpleCacheKeyImpl : ICacheKeyGenerator
{
private readonly string Prefix;
private readonly HashAlg Digest;
private readonly HashEncodingMode Encoding;
public SimpleCacheKeyImpl(string prefix, HashAlg digest, HashEncodingMode encoding)
{
Prefix = prefix;
Digest = digest;
Encoding = encoding;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private int ComputeBufferSize(string id) => id.Length + Prefix.Length;
string ICacheKeyGenerator.ComputedKey(string entityId)
{
//Compute the required character buffer size
int bufferSize = ComputeBufferSize(entityId);
if(bufferSize < 128)
{
//Stack alloc a buffer
Span<char> buffer = stackalloc char[bufferSize];
//Writer to accumulate data
ForwardOnlyWriter<char> writer = new(buffer);
//Append prefix and entity id
writer.Append(Prefix);
writer.Append(entityId);
//Compute the simple hash of the combined values
return ManagedHash.ComputeHash(writer.AsSpan(), Digest, Encoding);
}
else
{
//Alloc heap buffer for string concatination
using UnsafeMemoryHandle<char> buffer = MemoryUtil.UnsafeAlloc<char>(bufferSize, true);
//Writer to accumulate data
ForwardOnlyWriter<char> writer = new(buffer);
//Append prefix and entity id
writer.Append(Prefix);
writer.Append(entityId);
//Compute the simple hash of the combined values
return ManagedHash.ComputeHash(writer.AsSpan(), Digest, Encoding);
}
}
}
}
}
|
