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Reduce memory allocation in HttpMessageSanitizer (Azure#43818)
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2 files changed

+201
-91
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2 files changed

+201
-91
lines changed

‎sdk/core/Azure.Core/perf/HttpMessageSanitizerBenchmark.cs‎

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// Copyright (c) Microsoft Corporation. All rights reserved.
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// Licensed under the MIT License.
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using System;
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using BenchmarkDotNet.Attributes;
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namespace Azure.Core.Perf;
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[MemoryDiagnoser]
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public class HttpMessageSanitizerBenchmark
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{
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private HttpMessageSanitizer _sanitizer;
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[GlobalSetup]
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public void Setup()
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{
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_sanitizer = new HttpMessageSanitizer(
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allowedQueryParameters: new[] { "api-version" },
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allowedHeaders: Array.Empty<string>()
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);
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}
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[Benchmark]
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public string SanitizeHeader()
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{
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return _sanitizer.SanitizeHeader("header", "value");
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}
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[Benchmark]
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public string SanitizeUrl()
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{
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return _sanitizer.SanitizeUrl("https://www.example.com");
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}
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[Benchmark]
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public string SanitizeUrlWithQueryNoValue()
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{
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return _sanitizer.SanitizeUrl("https://www.example.com?param1");
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}
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[Benchmark]
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public string SanitizeUrlWithAllowedQuery()
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{
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return _sanitizer.SanitizeUrl("https://www.example.com?api-version=2024-05-01");
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}
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[Benchmark]
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public string SanitizeUrlWithDisallowedQuery()
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{
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return _sanitizer.SanitizeUrl("https://www.example.com?param1=value1");
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}
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}

‎sdk/core/Azure.Core/src/Shared/HttpMessageSanitizer.cs‎

Lines changed: 149 additions & 91 deletions
Original file line numberDiff line numberDiff line change
@@ -1,140 +1,198 @@
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// Licensed under the MIT License.
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#nullable enable
34

45
using System;
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using System.Collections.Generic;
67
using System.Text;
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using System.Linq;
89

9-
namespace Azure.Core
10+
namespace Azure.Core;
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internal class HttpMessageSanitizer
1013
{
11-
internal class HttpMessageSanitizer
12-
{
13-
private const string LogAllValue = "*";
14-
private readonly bool _logAllHeaders;
15-
private readonly bool _logFullQueries;
16-
private readonly string[] _allowedQueryParameters;
17-
private readonly string _redactedPlaceholder;
18-
private readonly HashSet<string> _allowedHeaders;
14+
private const string LogAllValue = "*";
15+
private readonly bool _logAllHeaders;
16+
private readonly bool _logFullQueries;
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private readonly string[] _allowedQueryParameters;
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private readonly string _redactedPlaceholder;
19+
private readonly HashSet<string> _allowedHeaders;
1920

20-
internal static HttpMessageSanitizer Default = new HttpMessageSanitizer(Array.Empty<string>(), Array.Empty<string>());
21+
[ThreadStatic]
22+
private static StringBuilder? s_cachedStringBuilder;
23+
private const int MaxCachedStringBuilderCapacity = 1024;
2124

22-
public HttpMessageSanitizer(string[] allowedQueryParameters, string[] allowedHeaders, string redactedPlaceholder = "REDACTED")
23-
{
24-
_logAllHeaders = allowedHeaders.Contains(LogAllValue);
25-
_logFullQueries = allowedQueryParameters.Contains(LogAllValue);
25+
internal static HttpMessageSanitizer Default = new HttpMessageSanitizer(Array.Empty<string>(), Array.Empty<string>());
2626

27-
_allowedQueryParameters = allowedQueryParameters;
28-
_redactedPlaceholder = redactedPlaceholder;
29-
_allowedHeaders = new HashSet<string>(allowedHeaders, StringComparer.InvariantCultureIgnoreCase);
30-
}
27+
public HttpMessageSanitizer(string[] allowedQueryParameters, string[] allowedHeaders, string redactedPlaceholder = "REDACTED")
28+
{
29+
_logAllHeaders = allowedHeaders.Contains(LogAllValue);
30+
_logFullQueries = allowedQueryParameters.Contains(LogAllValue);
3131

32-
public string SanitizeHeader(string name, string value)
33-
{
34-
if (_logAllHeaders || _allowedHeaders.Contains(name))
35-
{
36-
return value;
37-
}
32+
_allowedQueryParameters = allowedQueryParameters;
33+
_redactedPlaceholder = redactedPlaceholder;
34+
_allowedHeaders = new HashSet<string>(allowedHeaders, StringComparer.InvariantCultureIgnoreCase);
35+
}
3836

39-
return _redactedPlaceholder;
37+
public string SanitizeHeader(string name, string value)
38+
{
39+
if (_logAllHeaders || _allowedHeaders.Contains(name))
40+
{
41+
return value;
4042
}
4143

42-
public string SanitizeUrl(string url)
44+
return _redactedPlaceholder;
45+
}
46+
47+
public string SanitizeUrl(string url)
48+
{
49+
if (_logFullQueries)
4350
{
44-
if (_logFullQueries)
45-
{
46-
return url;
47-
}
51+
return url;
52+
}
4853

4954
#if NET5_0_OR_GREATER
50-
int indexOfQuerySeparator = url.IndexOf('?', StringComparison.Ordinal);
55+
int indexOfQuerySeparator = url.IndexOf('?', StringComparison.Ordinal);
5156
#else
52-
int indexOfQuerySeparator = url.IndexOf('?');
57+
int indexOfQuerySeparator = url.IndexOf('?');
5358
#endif
5459

55-
if (indexOfQuerySeparator == -1)
60+
if (indexOfQuerySeparator == -1)
61+
{
62+
return url;
63+
}
64+
65+
// PERF: Avoid allocations in this heavily-used method:
66+
// 1. Use ReadOnlySpan<char> to avoid creating substrings.
67+
// 2. Defer creating a StringBuilder until absolutely necessary.
68+
// 3. Use a rented StringBuilder to avoid allocating a new one
69+
// each time.
70+
71+
// Create the StringBuilder only when necessary (when we encounter
72+
// a query parameter that needs to be redacted)
73+
StringBuilder? stringBuilder = null;
74+
75+
// Keeps track of the number of characters we've processed so far
76+
// so that, if we need to create a StringBuilder, we know how many
77+
// characters to copy over from the original URL.
78+
int lengthSoFar = indexOfQuerySeparator + 1;
79+
80+
ReadOnlySpan<char> query = url.AsSpan(indexOfQuerySeparator + 1); // +1 to skip the '?'
81+
82+
while (query.Length > 0)
83+
{
84+
int endOfParameterValue = query.IndexOf('&');
85+
int endOfParameterName = query.IndexOf('=');
86+
bool noValue = false;
87+
88+
// Check if we have parameter without value
89+
if ((endOfParameterValue == -1 && endOfParameterName == -1) ||
90+
(endOfParameterValue != -1 && (endOfParameterName == -1 || endOfParameterName > endOfParameterValue)))
5691
{
57-
return url;
92+
endOfParameterName = endOfParameterValue;
93+
noValue = true;
5894
}
5995

60-
StringBuilder stringBuilder = new StringBuilder(url.Length);
61-
stringBuilder.Append(url, 0, indexOfQuerySeparator);
96+
if (endOfParameterName == -1)
97+
{
98+
endOfParameterName = query.Length;
99+
}
62100

63-
string query = url.Substring(indexOfQuerySeparator);
101+
if (endOfParameterValue == -1)
102+
{
103+
endOfParameterValue = query.Length;
104+
}
105+
else
106+
{
107+
// include the separator
108+
endOfParameterValue++;
109+
}
64110

65-
int queryIndex = 1;
66-
stringBuilder.Append('?');
111+
ReadOnlySpan<char> parameterName = query.Slice(0, endOfParameterName);
67112

68-
do
113+
bool isAllowed = false;
114+
foreach (string name in _allowedQueryParameters)
69115
{
70-
int endOfParameterValue = query.IndexOf('&', queryIndex);
71-
int endOfParameterName = query.IndexOf('=', queryIndex);
72-
bool noValue = false;
73-
74-
// Check if we have parameter without value
75-
if ((endOfParameterValue == -1 && endOfParameterName == -1) ||
76-
(endOfParameterValue != -1 && (endOfParameterName == -1 || endOfParameterName > endOfParameterValue)))
116+
if (parameterName.Equals(name.AsSpan(), StringComparison.OrdinalIgnoreCase))
77117
{
78-
endOfParameterName = endOfParameterValue;
79-
noValue = true;
118+
isAllowed = true;
119+
break;
80120
}
121+
}
81122

82-
if (endOfParameterName == -1)
83-
{
84-
endOfParameterName = query.Length;
85-
}
123+
int valueLength = endOfParameterValue;
124+
int nameLength = endOfParameterName;
86125

87-
if (endOfParameterValue == -1)
126+
if (isAllowed || noValue)
127+
{
128+
if (stringBuilder is null)
88129
{
89-
endOfParameterValue = query.Length;
130+
lengthSoFar += valueLength;
90131
}
91132
else
92133
{
93-
// include the separator
94-
endOfParameterValue++;
134+
AppendReadOnlySpan(stringBuilder, query.Slice(0, valueLength));
95135
}
136+
}
137+
else
138+
{
139+
// Encountered a query value that needs to be redacted.
140+
// Create the StringBuilder if we haven't already.
141+
stringBuilder ??= RentStringBuilder(url.Length).Append(url, 0, lengthSoFar);
96142

97-
ReadOnlySpan<char> parameterName = query.AsSpan(queryIndex, endOfParameterName - queryIndex);
143+
AppendReadOnlySpan(stringBuilder, query.Slice(0, nameLength))
144+
.Append('=')
145+
.Append(_redactedPlaceholder);
98146

99-
bool isAllowed = false;
100-
foreach (string name in _allowedQueryParameters)
147+
if (query[endOfParameterValue - 1] == '&')
101148
{
102-
if (parameterName.Equals(name.AsSpan(), StringComparison.OrdinalIgnoreCase))
103-
{
104-
isAllowed = true;
105-
break;
106-
}
149+
stringBuilder.Append('&');
107150
}
151+
}
152+
153+
query = query.Slice(valueLength);
154+
}
108155

109-
int valueLength = endOfParameterValue - queryIndex;
110-
int nameLength = endOfParameterName - queryIndex;
156+
return stringBuilder is null ? url : ToStringAndReturnStringBuilder(stringBuilder);
111157

112-
if (isAllowed)
113-
{
114-
stringBuilder.Append(query, queryIndex, valueLength);
115-
}
116-
else
117-
{
118-
if (noValue)
119-
{
120-
stringBuilder.Append(query, queryIndex, valueLength);
121-
}
122-
else
123-
{
124-
stringBuilder.Append(query, queryIndex, nameLength);
125-
stringBuilder.Append('=');
126-
stringBuilder.Append(_redactedPlaceholder);
127-
if (query[endOfParameterValue - 1] == '&')
128-
{
129-
stringBuilder.Append('&');
130-
}
131-
}
132-
}
158+
static StringBuilder AppendReadOnlySpan(StringBuilder builder, ReadOnlySpan<char> span)
159+
{
160+
#if NET6_0_OR_GREATER
161+
return builder.Append(span);
162+
#else
163+
foreach (char c in span)
164+
{
165+
builder.Append(c);
166+
}
167+
168+
return builder;
169+
#endif
170+
}
171+
}
172+
173+
private static StringBuilder RentStringBuilder(int capacity)
174+
{
175+
if (capacity <= MaxCachedStringBuilderCapacity)
176+
{
177+
StringBuilder? builder = s_cachedStringBuilder;
178+
if (builder is not null && builder.Capacity >= capacity)
179+
{
180+
s_cachedStringBuilder = null;
181+
return builder;
182+
}
183+
}
133184

134-
queryIndex += valueLength;
135-
} while (queryIndex < query.Length);
185+
return new StringBuilder(capacity);
186+
}
136187

137-
return stringBuilder.ToString();
188+
private static string ToStringAndReturnStringBuilder(StringBuilder builder)
189+
{
190+
string result = builder.ToString();
191+
if (builder.Capacity <= MaxCachedStringBuilderCapacity)
192+
{
193+
s_cachedStringBuilder = builder.Clear();
138194
}
195+
196+
return result;
139197
}
140198
}

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