Cache tags from DbCommand (#774)
* Cache the tags extracted from connection strings * Disable the cache if too many different connection strings are used
This commit is contained in:
Kevin Gosse
GitHub
parent
6a1abe0a45
commit
382ea15cb0
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@ -1,6 +1,7 @@
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using System;
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using System.Data;
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using System.Data.Common;
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using Datadog.Trace.Util;
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namespace Datadog.Trace.ExtensionMethods
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{
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@ -34,17 +35,12 @@ namespace Datadog.Trace.ExtensionMethods
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span.ResourceName = command.CommandText;
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span.Type = SpanTypes.Sql;
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// parse the connection string
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var builder = new DbConnectionStringBuilder { ConnectionString = command.Connection.ConnectionString };
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var tags = DbCommandCache.GetTagsFromDbCommand(command);
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string database = GetConnectionStringValue(builder, "Database", "Initial Catalog", "InitialCatalog");
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span.SetTag(Tags.DbName, database);
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string user = GetConnectionStringValue(builder, "User ID", "UserID");
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span.SetTag(Tags.DbUser, user);
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string server = GetConnectionStringValue(builder, "Server", "Data Source", "DataSource", "Network Address", "NetworkAddress", "Address", "Addr", "Host");
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span.SetTag(Tags.OutHost, server);
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foreach (var pair in tags)
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{
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span.SetTag(pair.Key, pair.Value);
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}
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}
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internal static void DecorateWebServerSpan(
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@ -62,19 +58,5 @@ namespace Datadog.Trace.ExtensionMethods
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span.SetTag(Tags.HttpUrl, httpUrl);
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span.SetTag(Tags.Language, TracerConstants.Language);
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}
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private static string GetConnectionStringValue(DbConnectionStringBuilder builder, params string[] names)
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{
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foreach (string name in names)
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{
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if (builder.TryGetValue(name, out object valueObj) &&
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valueObj is string value)
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{
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return value;
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}
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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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@ -0,0 +1,104 @@
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using System.Collections.Concurrent;
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using System.Collections.Generic;
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using System.Data;
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using System.Data.Common;
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using System.Threading;
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using Datadog.Trace.Logging;
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using Datadog.Trace.Vendors.Serilog;
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namespace Datadog.Trace.Util
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{
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internal static class DbCommandCache
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{
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internal const int MaxConnectionStrings = 100;
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private static readonly ILogger Log = DatadogLogging.GetLogger(typeof(DbCommandCache));
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private static ConcurrentDictionary<string, KeyValuePair<string, string>[]> _cache
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= new ConcurrentDictionary<string, KeyValuePair<string, string>[]>();
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/// <summary>
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/// Gets or sets the underlying cache, to be used for unit tests
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/// </summary>
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internal static ConcurrentDictionary<string, KeyValuePair<string, string>[]> Cache
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{
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get
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{
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return _cache;
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}
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set
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{
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_cache = value;
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}
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}
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public static KeyValuePair<string, string>[] GetTagsFromDbCommand(IDbCommand command)
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{
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var connectionString = command.Connection.ConnectionString;
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var cache = _cache;
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if (cache != null)
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{
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if (cache.TryGetValue(connectionString, out var tags))
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{
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// Fast path: it's expected that most calls will end up in this branch
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return tags;
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}
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if (cache.Count <= MaxConnectionStrings)
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{
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// Populating the cache. This path should be hit only during application warmup
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// ReSharper disable once ConvertClosureToMethodGroup -- Lambdas are cached by the compiler
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return cache.GetOrAdd(connectionString, cs => ExtractTagsFromConnectionString(cs));
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}
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// The assumption "connection strings are a finite set" was wrong, disabling the cache
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// Use atomic operation to log only once
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if (Interlocked.Exchange(ref _cache, null) != null)
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{
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Log.Information($"More than {MaxConnectionStrings} different connection strings were used, disabling cache");
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}
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}
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// Fallback: too many different connection string, there might be a random part in them
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// Stop using the cache to prevent memory leaks
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return ExtractTagsFromConnectionString(connectionString);
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}
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private static KeyValuePair<string, string>[] ExtractTagsFromConnectionString(string connectionString)
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{
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// Parse the connection string
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var builder = new DbConnectionStringBuilder { ConnectionString = connectionString };
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return new[]
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{
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new KeyValuePair<string, string>(
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Tags.DbName,
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GetConnectionStringValue(builder, "Database", "Initial Catalog", "InitialCatalog")),
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new KeyValuePair<string, string>(
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Tags.DbUser,
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GetConnectionStringValue(builder, "User ID", "UserID")),
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new KeyValuePair<string, string>(
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Tags.OutHost,
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GetConnectionStringValue(builder, "Server", "Data Source", "DataSource", "Network Address", "NetworkAddress", "Address", "Addr", "Host"))
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};
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}
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private static string GetConnectionStringValue(DbConnectionStringBuilder builder, params string[] names)
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{
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foreach (string name in names)
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{
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if (builder.TryGetValue(name, out object valueObj) &&
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valueObj is string value)
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{
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return value;
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}
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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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@ -0,0 +1,97 @@
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using System.Collections.Concurrent;
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using System.Collections.Generic;
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using System.Data;
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using Datadog.Trace.ExtensionMethods;
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using Datadog.Trace.Util;
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using Moq;
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using Xunit;
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namespace Datadog.Trace.Tests.ExtensionMethods
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{
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public class SpanExtensionsTests
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{
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public SpanExtensionsTests()
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{
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// Reset the cache
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DbCommandCache.Cache = new ConcurrentDictionary<string, KeyValuePair<string, string>[]>();
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}
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[Theory]
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[InlineData("Server=myServerName,myPortNumber;Database=myDataBase;User Id=myUsername;Password=myPassword;", "myDataBase", "myUsername", "myServerName,myPortNumber")]
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[InlineData(@"Server=myServerName\myInstanceName;Database=myDataBase;User Id=myUsername;Password=myPassword;", "myDataBase", "myUsername", @"myServerName\myInstanceName")]
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[InlineData(@"Server=.\SQLExpress;AttachDbFilename=|DataDirectory|mydbfile.mdf;Database=dbname;Trusted_Connection=Yes;", "dbname", null, @".\SQLExpress")]
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public void ExtractProperTagsFromConnectionString(
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string connectionString,
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string expectedDbName,
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string expectedUserId,
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string expectedHost)
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{
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var spanContext = new SpanContext(Mock.Of<ISpanContext>(), Mock.Of<ITraceContext>(), "test");
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var span = new Span(spanContext, null);
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span.AddTagsFromDbCommand(CreateDbCommand(connectionString));
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Assert.Equal(expectedDbName, span.GetTag(Tags.DbName));
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Assert.Equal(expectedUserId, span.GetTag(Tags.DbUser));
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Assert.Equal(expectedHost, span.GetTag(Tags.OutHost));
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}
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[Fact]
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public void SetSpanTypeToSql()
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{
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const string connectionString = "Server=myServerName;Database=myDataBase;User Id=myUsername;Password=myPassword;";
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const string commandText = "SELECT * FROM Table ORDER BY id";
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var spanContext = new SpanContext(Mock.Of<ISpanContext>(), Mock.Of<ITraceContext>(), "test");
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var span = new Span(spanContext, null);
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span.AddTagsFromDbCommand(CreateDbCommand(connectionString, commandText));
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Assert.Equal(SpanTypes.Sql, span.Type);
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Assert.Equal(commandText, span.ResourceName);
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}
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[Fact]
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public void ShouldDisableCacheIfTooManyConnectionStrings()
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{
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const string connectionStringTemplate = "Server=myServerName{0};Database=myDataBase;User Id=myUsername;Password=myPassword;";
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var spanContext = new SpanContext(Mock.Of<ISpanContext>(), Mock.Of<ITraceContext>(), "test");
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var span = new Span(spanContext, null);
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// Fill-up the cache and test the logic with cache enabled
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for (int i = 0; i <= DbCommandCache.MaxConnectionStrings; i++)
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{
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var connectionString = string.Format(connectionStringTemplate, i);
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span.AddTagsFromDbCommand(CreateDbCommand(connectionString));
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Assert.NotNull(DbCommandCache.Cache);
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Assert.Equal("myServerName" + i, span.GetTag(Tags.OutHost));
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}
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// Test the logic with cache disabled
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for (int i = 0; i <= 10; i++)
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{
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var connectionString = string.Format(connectionStringTemplate, "NoCache" + i);
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span.AddTagsFromDbCommand(CreateDbCommand(connectionString));
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Assert.Null(DbCommandCache.Cache);
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Assert.Equal("myServerName" + "NoCache" + i, span.GetTag(Tags.OutHost));
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}
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}
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private static IDbCommand CreateDbCommand(string connectionString, string commandText = null)
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{
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var dbConnection = new Mock<IDbConnection>();
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dbConnection.SetupGet(c => c.ConnectionString).Returns(connectionString);
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var dbCommand = new Mock<IDbCommand>();
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dbCommand.SetupGet(c => c.Connection).Returns(dbConnection.Object);
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dbCommand.SetupGet(c => c.CommandText).Returns(commandText);
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return dbCommand.Object;
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}
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}
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}
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