chore: yggdrasil

[nunogois]

https://linear.app/unleash/issue/2-1545/yggdrasil-net-integrate-into-unleashclient-net-sdk

This incorporates Yggdrasil into the .NET SDK, using the new Unleash.Yggdrasil NuGet package.

The PR tries to target as small of a change surface as possible, however some things simply no longer made sense or needed to change to accommodate this change to the new Yggdrasil engine.

After this change we can consider removing a big part of what can now be considered "dead code". There are a lot of refactoring opportunities. We should also consider favoring state literal strings in tests over constructing the state with the current classes. However all of this is out of scope for this PR.

Some changes that affect the public interface and usability of the SDK include:

• Due to Unleash.Yggdrasil's target of .NET Standard 2.0, we're dropping support for:
  • .NET Framework 4.7;
  • .NET Framework 4.6.1;
  • .NET Framework 4.6;
  • .NET Framework 4.5.1;
  • .NET Framework 4.5;
• In the Unleash client, we no longer expose:
  • FeatureToggles;
  • GetVariants;
• IStrategy -> Yggdrasil.IStrategy at Unleash client creation, for custom strategies;
• IToggleBootstrapProvider.Read() should now return a state string instead of a ToggleCollection;
• UnleashServices now logs an error and emits a FileCache error whenever YggdrasilEngine fails to load initial state;

Some changes that are internal to the SDK include:

• FetchTogglesResult drops ToggleCollection in favor of State;
• SendMetrics now takes in an Yggdrasil.MetricsBucket instead of a ThreadSafeMetricsBucket;
• CachedFilesLoader no longer needs a serializer, since it uses the file string content as is;
• CachedFilesLoader drops InitialToggleCollection in favor of InitialState;
• UnleashServices now holds a list of DefaultStrategyNames in order to register them as part of metrics;
• UnleashServices no longer initializes a ToggleCollection and MetricsBucket. Instead, it initializes an YggdrasilEngine;
• Variant now inherits from Yggdrasil.Variant;
• Payload now inherits from Yggdrasil.Payload;
• UnleashContext now inherits from Yggdrasil.Context;
• ClientMetricsBackgroundTask drops ThreadSafeMetricsBucket in favor of YggdrasilEngine;
• FetchFeatureTogglesTask drops ThreadSafeToggleCollection and IJsonSerializer in favor of YggdrasilEngine;
• Due to the simplification of some processes, like (de)serialization of state, some tests were simplified, adapted or removed. They can probably be simplified further on a later PR;

We also fixed some SDK behaviors that followed wrong assumptions.

For more details, feel free to ask or check the diff directly.

[nunogois]

Rebased this and cleaned it up a bit. @sighphyre let me know when you think it's a good time to merge this. I suggest taking another look just in case 😄

[rcollette]

What architectures are going to be supported in docker containers? I've been getting burned by rust/go .NET integrations lately where the producing teams do not have access to ARM64 platforms on which to build and code that runs on my local machine, fails to build in a docker on ARM64 Macs.

[sighphyre]

What architectures are going to be supported in docker containers? I've been getting burned by rust/go .NET integrations lately where the producing teams do not have access to ARM64 platforms on which to build and code that runs on my local machine, fails to build in a docker on ARM64 Macs.

Out the box, likely x86 Windows/MacOS/Linux + ARM MacOS. Right now there's no Github runners for ARM Windows/Linux, not a blocker but we likely won't go through the dance of setting up a custom runner unless someone asks

Edit: Okay Linux ARM builds will be in by default too, probably