Commits on Jul 4, 2024

1. Fix race condition in EnhancedHttpRetryHelper …

   When multiple threads try to access the `RetryCount` property we sometimes hit a case where `RetryCount` returned 0 (*).
   This caused the loop in `ProcessHttpSourceResultAsync()` to be skipped completely because `retry <= maxRetries`: https://github.com/NuGet/NuGet.Client/blob/6c642c2d63717acd4bf92050a42691928020eb89/src/NuGet.Core/NuGet.Protocol/Utility/FindPackagesByIdNupkgDownloader.cs#L258-L328
   
   Fix this by using `Lazy<T>` for initializing the fields which is thread-safe.
   
   Fixes NuGet/Home#13545
   
   (*) The reason is that code like `int RetryCount => _retryCount ??= 6;` gets turned into:
   
   ```csharp
   int valueOrDefault = _retryCount.GetValueOrDefault();
   if (!_retryCount.HasValue)
   {
       valueOrDefault = 6;
       _retryCount = valueOrDefault;
       return valueOrDefault;
   }
   return valueOrDefault;
   ```
   
   Suppose Thread A arrives first and calls `GetValueOrDefault()` (which is 0 for int) but then Thread B interjects and sets the value, now when Thread A resumes `_retryCount.HasValue` is true so we skip the if block and return valueOrDefault i.e. 0.

   

   akoeplinger committed Jul 4, 2024
   Configuration menu

   • View commit details
   • Copy full SHA for 41d7bfc
   • Browse repository at this point

   Copy the full SHA

   41d7bfc View commit details

   Browse the repository at this point in the history