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Connection limits: Fixes .NET core to honor gateway connection limit (#…
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…1740)

* Initial fix

* Gateway connection limits: Fix .NET core to honor connection limit

* Added more tests and blocks
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@j82w
j82w authored Jul 30, 2020
1 parent 88f3f43 commit b45c9da
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Showing 4 changed files with 144 additions and 17 deletions.
15 changes: 12 additions & 3 deletions Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ namespace Microsoft.Azure.Cosmos
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Security.AccessControl;
using Microsoft.Azure.Cosmos.Fluent;
using Microsoft.Azure.Documents;
using Microsoft.Azure.Documents.Client;
Expand Down Expand Up @@ -136,9 +137,9 @@ public int GatewayModeMaxConnectionLimit
throw new ArgumentOutOfRangeException(nameof(value));
}

if (this.ConnectionMode != ConnectionMode.Gateway)
if (this.HttpClientFactory != null && value != ConnectionPolicy.Default.MaxConnectionLimit )
{
throw new ArgumentException("Max connection limit is only valid for ConnectionMode.Gateway.");
throw new ArgumentException($"{nameof(this.httpClientFactory)} can not be set along with {nameof(this.GatewayModeMaxConnectionLimit)}. This must be set on the HttpClientHandler.MaxConnectionsPerServer property.");
}

this.gatewayModeMaxConnectionLimit = value;
Expand Down Expand Up @@ -468,6 +469,9 @@ public CosmosSerializer Serializer
/// <para>
/// Useful in scenarios where the application is using a pool of HttpClient instances to be shared, like ASP.NET Core applications with IHttpClientFactory or Blazor WebAssembly applications.
/// </para>
/// <para>
/// For .NET core applications the default GatewayConnectionLimit will be ignored. It must be set on the HttpClientHandler.MaxConnectionsPerServer to limit the number of connections
/// </para>
/// </remarks>
[JsonIgnore]
public Func<HttpClient> HttpClientFactory
Expand All @@ -480,6 +484,11 @@ public Func<HttpClient> HttpClientFactory
throw new ArgumentException($"{nameof(this.HttpClientFactory)} cannot be set along {nameof(this.WebProxy)}");
}

if (this.GatewayModeMaxConnectionLimit != ConnectionPolicy.Default.MaxConnectionLimit)
{
throw new ArgumentException($"{nameof(this.httpClientFactory)} can not be set along with {nameof(this.GatewayModeMaxConnectionLimit)}. This must be set on the HttpClientHandler.MaxConnectionsPerServer property.");
}

this.httpClientFactory = value;
}
}
Expand Down Expand Up @@ -623,7 +632,7 @@ internal ConnectionPolicy GetConnectionPolicy()
EnableEndpointDiscovery = !this.LimitToEndpoint,
PortReuseMode = this.portReuseMode,
EnableTcpConnectionEndpointRediscovery = this.EnableTcpConnectionEndpointRediscovery,
HttpClientFactory = this.httpClientFactory
HttpClientFactory = this.httpClientFactory,
};

if (this.ApplicationRegion != null)
Expand Down
10 changes: 6 additions & 4 deletions Microsoft.Azure.Cosmos/src/Resource/ClientContextCore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -464,14 +464,16 @@ private bool IsBulkOperationSupported(

private static HttpClientHandler CreateHttpClientHandler(CosmosClientOptions clientOptions)
{
if (clientOptions == null || clientOptions.WebProxy == null)
if (clientOptions == null)
{
return null;
throw new ArgumentNullException(nameof(clientOptions));
}


// https://docs.microsoft.com/en-us/archive/blogs/timomta/controlling-the-number-of-outgoing-connections-from-httpclient-net-core-or-full-framework
HttpClientHandler httpClientHandler = new HttpClientHandler
{
Proxy = clientOptions.WebProxy
Proxy = clientOptions.WebProxy,
MaxConnectionsPerServer = clientOptions.GatewayModeMaxConnectionLimit
};

return httpClientHandler;
Expand Down
112 changes: 102 additions & 10 deletions Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.EmulatorTests/ClientTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,14 @@
namespace Microsoft.Azure.Cosmos.SDK.EmulatorTests
{
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.NetworkInformation;
using System.Reflection;
using System.Threading.Tasks;
using Microsoft.Azure.Cosmos.Query.Core;
using Microsoft.Azure.Cosmos.Services.Management.Tests.LinqProviderTests;
Expand All @@ -30,13 +35,13 @@ public async Task ResourceResponseStreamingTest()

Database db = (await client.CreateDatabaseAsync(new Database() { Id = Guid.NewGuid().ToString() })).Resource;
DocumentCollection coll = await TestCommon.CreateCollectionAsync(client, db, new DocumentCollection()
{
Id = Guid.NewGuid().ToString(),
PartitionKey = new PartitionKeyDefinition()
{
Paths = new System.Collections.ObjectModel.Collection<string>() { "/id" }
}
});
{
Id = Guid.NewGuid().ToString(),
PartitionKey = new PartitionKeyDefinition()
{
Paths = new System.Collections.ObjectModel.Collection<string>() { "/id" }
}
});
ResourceResponse<Document> doc = await client.CreateDocumentAsync(coll.SelfLink, new Document() { Id = Guid.NewGuid().ToString() });

Assert.AreEqual(doc.ResponseStream.Position, 0);
Expand Down Expand Up @@ -281,7 +286,8 @@ public async Task VerifyNegativeWebProxySettings()
}
);

await Assert.ThrowsExceptionAsync<HttpRequestException>(async () => {
await Assert.ThrowsExceptionAsync<HttpRequestException>(async () =>
{
DatabaseResponse databaseResponse = await cosmosClient.CreateDatabaseAsync(Guid.NewGuid().ToString());
});

Expand All @@ -298,7 +304,8 @@ await Assert.ThrowsExceptionAsync<HttpRequestException>(async () => {
}
);

await Assert.ThrowsExceptionAsync<HttpRequestException>(async () => {
await Assert.ThrowsExceptionAsync<HttpRequestException>(async () =>
{
DatabaseResponse databaseResponse = await cosmosClient.CreateDatabaseAsync(Guid.NewGuid().ToString());
});
}
Expand Down Expand Up @@ -335,12 +342,97 @@ public async Task HttpClientFactorySmokeTest()
}
finally
{
if (database!= null)
if (database != null)
{
await database.DeleteAsync();
}
}
}

[TestMethod]
public async Task HttpClientConnectionLimitTest()
{
int gatewayConnectionLimit = 1;

IReadOnlyList<string> excludeConnections = GetActiveConnections();
CosmosClient cosmosClient = new CosmosClient(
ConfigurationManager.AppSettings["GatewayEndpoint"],
ConfigurationManager.AppSettings["MasterKey"],
new CosmosClientOptions
{
ApplicationName = "test",
GatewayModeMaxConnectionLimit = gatewayConnectionLimit,
ConnectionMode = ConnectionMode.Gateway,
ConnectionProtocol = Protocol.Https
}
);

DelegatingHandler handler = (DelegatingHandler)cosmosClient.DocumentClient.httpMessageHandler;
HttpClientHandler httpClientHandler = (HttpClientHandler)handler.InnerHandler;
Assert.AreEqual(gatewayConnectionLimit, httpClientHandler.MaxConnectionsPerServer);

Cosmos.Database database = await cosmosClient.CreateDatabaseAsync(Guid.NewGuid().ToString());
Container container = await database.CreateContainerAsync(
"TestConnections",
"/pk",
throughput: 20000);

List<Task> creates = new List<Task>();
for (int i = 0; i < 100; i++)
{
creates.Add(container.CreateItemAsync<dynamic>(new { id = Guid.NewGuid().ToString(), pk = Guid.NewGuid().ToString() }));
}

await Task.WhenAll(creates);

// Verify the handler still exists after client warm up
//Assert.AreEqual(gatewayConnectionLimit, httpClientHandler.MaxConnectionsPerServer);
IReadOnlyList<string> afterConnections = GetActiveConnections();

// Clean up the database and container
await database.DeleteAsync();

int connectionDiff = afterConnections.Count - excludeConnections.Count;
Assert.IsTrue(connectionDiff <= gatewayConnectionLimit, $"Connection before : {excludeConnections.Count}, after {afterConnections.Count}");
}

public static IReadOnlyList<string> GetActiveConnections()
{
string testPid = Process.GetCurrentProcess().Id.ToString();
using (Process p = new Process())
{
ProcessStartInfo ps = new ProcessStartInfo();
ps.Arguments = "-a -n -o";
ps.FileName = "netstat.exe";
ps.UseShellExecute = false;
ps.WindowStyle = ProcessWindowStyle.Hidden;
ps.RedirectStandardInput = true;
ps.RedirectStandardOutput = true;
ps.RedirectStandardError = true;

p.StartInfo = ps;
p.Start();

StreamReader stdOutput = p.StandardOutput;
StreamReader stdError = p.StandardError;

string content = stdOutput.ReadToEnd() + stdError.ReadToEnd();
string exitStatus = p.ExitCode.ToString();

if (exitStatus != "0")
{
// Command Errored. Handle Here If Need Be
}

List<string> connections = content.Split(Environment.NewLine, StringSplitOptions.RemoveEmptyEntries)
.Select(x => x.Trim())
.Where(x => x.EndsWith(testPid)).ToList();

Assert.IsTrue(connections.Count > 0);

return connections;
}
}
}

internal static class StringHelper
Expand Down
24 changes: 24 additions & 0 deletions Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosClientOptionsUnitTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,30 @@ public void VerifyHttpClientHandlerSettingsThrowIfNotUsedInGatewayMode()
Assert.ThrowsException<ArgumentException>(() => { cosmosClientOptions.WebProxy = new TestWebProxy(); });
}

[TestMethod]
public void VerifyHttpClientFactoryBlockedWithConnectionLimit()
{
CosmosClientOptions cosmosClientOptions = new CosmosClientOptions()
{
GatewayModeMaxConnectionLimit = 42
};

Assert.ThrowsException<ArgumentException>(() =>
{
cosmosClientOptions.HttpClientFactory = () => new HttpClient();
});

cosmosClientOptions = new CosmosClientOptions()
{
HttpClientFactory = () => new HttpClient()
};

Assert.ThrowsException<ArgumentException>(() =>
{
cosmosClientOptions.GatewayModeMaxConnectionLimit = 42;
});
}

[TestMethod]
public void VerifyHttpClientHandlerIsSet()
{
Expand Down

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