100 lines
3.6 KiB
C#
100 lines
3.6 KiB
C#
// <copyright file="PropertyFetcher.cs" company="OpenTelemetry Authors">
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// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// </copyright>
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using System;
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using System.Linq;
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using System.Reflection;
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namespace OpenTelemetry.Instrumentation.GrpcNetClient.Implementation
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{
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internal class PropertyFetcher
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{
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private readonly string propertyName;
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private PropertyFetch innerFetcher;
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public PropertyFetcher(string propertyName)
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{
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this.propertyName = propertyName;
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}
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public object Fetch(object obj)
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{
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if (this.innerFetcher == null)
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{
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var type = obj.GetType().GetTypeInfo();
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var property = type.DeclaredProperties.FirstOrDefault(p => string.Equals(p.Name, this.propertyName, StringComparison.InvariantCultureIgnoreCase));
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if (property == null)
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{
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property = type.GetProperty(this.propertyName);
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}
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this.innerFetcher = PropertyFetch.FetcherForProperty(property);
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}
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return this.innerFetcher?.Fetch(obj);
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}
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// see https://github.com/dotnet/corefx/blob/master/src/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/DiagnosticSourceEventSource.cs
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private class PropertyFetch
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{
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/// <summary>
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/// Create a property fetcher from a .NET Reflection PropertyInfo class that
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/// represents a property of a particular type.
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/// </summary>
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public static PropertyFetch FetcherForProperty(PropertyInfo propertyInfo)
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{
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if (propertyInfo == null)
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{
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// returns null on any fetch.
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return new PropertyFetch();
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}
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var typedPropertyFetcher = typeof(TypedFetchProperty<,>);
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var instantiatedTypedPropertyFetcher = typedPropertyFetcher.GetTypeInfo().MakeGenericType(
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propertyInfo.DeclaringType, propertyInfo.PropertyType);
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return (PropertyFetch)Activator.CreateInstance(instantiatedTypedPropertyFetcher, propertyInfo);
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}
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/// <summary>
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/// Given an object, fetch the property that this propertyFetch represents.
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/// </summary>
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public virtual object Fetch(object obj)
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{
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return null;
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}
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private class TypedFetchProperty<TObject, TProperty> : PropertyFetch
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{
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private readonly Func<TObject, TProperty> propertyFetch;
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public TypedFetchProperty(PropertyInfo property)
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{
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this.propertyFetch = (Func<TObject, TProperty>)property.GetMethod.CreateDelegate(typeof(Func<TObject, TProperty>));
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}
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public override object Fetch(object obj)
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{
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if (obj is TObject o)
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{
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return this.propertyFetch(o);
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}
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return null;
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}
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}
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}
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}
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}
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