Limit cached format values size

aspnet · Mar 16, 2017 · cc503aa · cc503aa
1 parent 5c3239f
commit cc503aa
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Showing 3 changed files with 44 additions and 1 deletion.
diff --git a/src/Microsoft.Extensions.Logging.Abstractions/Internal/FormattedLogValues.cs b/src/Microsoft.Extensions.Logging.Abstractions/Internal/FormattedLogValues.cs
@@ -5,6 +5,7 @@
 using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Threading;
 
 namespace Microsoft.Extensions.Logging.Internal
 {
@@ -14,17 +15,36 @@ namespace Microsoft.Extensions.Logging.Internal
     /// </summary>
     public class FormattedLogValues : IReadOnlyList<KeyValuePair<string, object>>
     {
+        internal const int MaxCachedFormatters = 1024;
         private const string NullFormat = "[null]";
+        private static int _count;
         private static ConcurrentDictionary<string, LogValuesFormatter> _formatters = new ConcurrentDictionary<string, LogValuesFormatter>();
         private readonly LogValuesFormatter _formatter;
         private readonly object[] _values;
         private readonly string _originalMessage;
 
+        // for testing purposes
+        internal LogValuesFormatter Formatter => _formatter;
+
         public FormattedLogValues(string format, params object[] values)
         {
             if (values?.Length != 0 && format != null)
             {
-                _formatter = _formatters.GetOrAdd(format, f => new LogValuesFormatter(f));
+                if (_count >= MaxCachedFormatters)
+                {
+                    if (!_formatters.TryGetValue(format, out _formatter))
+                    {
+                        _formatter = new LogValuesFormatter(format);
+                    }
+                }
+                else
+                {
+                    _formatter = _formatters.GetOrAdd(format, f =>
+                    {
+                        Interlocked.Increment(ref _count);
+                        return new LogValuesFormatter(f);
+                    });
+                }
             }
 
             _originalMessage = format ?? NullFormat;

diff --git a/src/Microsoft.Extensions.Logging.Abstractions/Properties/AssemblyInfo.cs b/src/Microsoft.Extensions.Logging.Abstractions/Properties/AssemblyInfo.cs
@@ -0,0 +1,6 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Microsoft.Extensions.Logging.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
diff --git a/test/Microsoft.Extensions.Logging.Test/FormattedLogValuesTest.cs b/test/Microsoft.Extensions.Logging.Test/FormattedLogValuesTest.cs
@@ -93,6 +93,23 @@ public void LogValues_With_UnbalancedBraces(string format)
             });
         }
 
+        [Fact]
+        public void CachedFormattersAreCapped()
+        {
+            for (var i = 0; i < FormattedLogValues.MaxCachedFormatters; ++i)
+            {
+                var ignore = new FormattedLogValues($"{i}{{i}}", i);
+            }
+
+            // check cached formatter
+            var formatter = new FormattedLogValues("0{i}", 0).Formatter;
+            Assert.Same(formatter, new FormattedLogValues("0{i}", 0).Formatter);
+
+            // check non-cached formatter
+            formatter = new FormattedLogValues("test {}", 0).Formatter;
+            Assert.NotSame(formatter, new FormattedLogValues("test {}", 0).Formatter);
+        }
+
         // message format, format arguments, expected message
         public static TheoryData<string, object[], string> FormatsEnumerableValuesData
         {