GetOrCreate / GetOrCreateAsync on IMemoryCache creates cache entry even when factory throws

[rmja]

It seems wrong that a cache entry is added with the value null when the factory method throws:

            try
            {
                memoryCache.GetOrCreate("key", entry =>
                {
                    throw new Exception();
                    return 123;
                });
            } catch (Exception e)
            {
                // memoryCache now has an entry for "key" with the value null. This seems odd.
            }

The expected behaviour should be that the value is not added to the cache if the factory throws.

[Tratcher]

Agreed. There should not be a using statement on this line:

Caching/src/Microsoft.Extensions.Caching.Abstractions/MemoryCacheExtensions.cs

Line 103 in c432e58

using (var entry = cache.CreateEntry(key))

[BrennanConroy]

18f2259

[gdoron]

When will preview 1 be released?
We just got hit hard by this bug, we'll might have to use the nightly builds on production 😢 until it's being released.