[BUG]: Unreadable stream

[mig42]

AAS extension version used

3.42.0

Operating system and platform

Windows (x64)

Language

.NET

Language Runtime Version

.NET 10

Bug Report

After upgrading the Datadog Extension in my Azure App Service, this code started failing:

using System.Text;
using Newtonsoft.Json;

namespace Test;

public class ApiClient
{
    public async Task<T> SendAsync<T>(
        HttpMethod method,
        Uri server,
        string path,
        object content,
        CancellationToken cancellationToken = default)
    {
        var completeUri = new Uri(server, path);

        using var request = new HttpRequestMessage(method, completeUri);
        request.Content = content == null ? null : new JsonStreamContent(content);

        var response = await httpClient.SendAsync(
            request,
            HttpCompletionOption.ResponseHeadersRead,
            cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var responseContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new MyServerException((int)response.StatusCode, responseContent);
        }

        await using var stream = await response.Content.ReadAsStreamAsync(cancellationToken);
        using var streamReader = new StreamReader(stream, Encoding.UTF8);
        await using var jsonReader = new JsonTextReader(streamReader);

        var serializer = JsonSerializer.CreateDefault();
        return serializer.Deserialize<T>(jsonReader);
    }
}

This line:

        using var streamReader = new StreamReader(stream, Encoding.UTF8);

randomly fails, causing this exception:

  System.ArgumentException: Stream was not readable.                                                                                                                                                                                                                                                               
     at System.IO.StreamReader..ctor(Stream stream, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize, Boolean leaveOpen)                                                                                                                                                              
     at System.IO.StreamReader..ctor(Stream stream, Encoding encoding)                                                                                                                                                                                                                                             
     at plasticscm.com.Api.Clients.Plastic.Server.ApiClient.SendAsync[T](HttpMethod method, Uri server, String path, Object content, String plasticUserHeader, String plasticToken, CancellationToken cancellationToken) in                                                                                        
  /buildpath/ApiClient.cs:line 31

The problem is intermitent, and it disappears if I remove the extension. This started happening when I upgraded the extension from 3.36.0 to 3.42.0. The randomness might be related to sampling not being 100%.

Reproduction Code

using System.Text;
using Newtonsoft.Json;

namespace Test;

public class ApiClient
{
    public async Task<T> SendAsync<T>(
        HttpMethod method,
        Uri server,
        string path,
        object content,
        CancellationToken cancellationToken = default)
    {
        var completeUri = new Uri(server, path);

        using var request = new HttpRequestMessage(method, completeUri);
        request.Content = content == null ? null : new JsonStreamContent(content);

        var response = await httpClient.SendAsync(
            request,
            HttpCompletionOption.ResponseHeadersRead,
            cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            var responseContent = await response.Content.ReadAsStringAsync(cancellationToken);
            throw new MyServerException((int)response.StatusCode, responseContent);
        }

        await using var stream = await response.Content.ReadAsStreamAsync(cancellationToken);
        using var streamReader = new StreamReader(stream, Encoding.UTF8);
        await using var jsonReader = new JsonTextReader(streamReader);

        var serializer = JsonSerializer.CreateDefault();
        return serializer.Deserialize<T>(jsonReader);
    }
}

[andrewlock]

Hi @mig42, sorry you're seeing the issue, thanks for reporting it. I'd suggest contacting support so that we can collect any additional information so we can get to the bottom of it. Out of interest, do you have ASM enabled?

[mig42]

Thanks for the advice @andrewlock ! I'll write in a minute. And regarding ASM: yes, we have it enabled in our App Service 🙂