Skip to content

v3.0.0
Compare
Choose a tag to compare
@lewislabs lewislabs released this 25 Oct 13:23
· 51 commits to master since this release
3.0.0
428b870

This release contains breaking changes.

Summary

Major themes:

  • Remove obsolete/deprecated functionality.
  • Focus on CommandInvoker as the library entry point
  • Remove external library dependencies (logging, config, thread pools, common)
  • Make all functionality injectable through ICommandInvoker instead of static assignments
  • .NET Core support

CommandInvoker becomes the sole entry point for the library. See its constructor overloads for DI options. CommandInvoker was introduced in 2.6.0, which is documented here.

Major changes

  • 0e36dd6 Removed old Command. SyncCommand and AsyncCommand, introduced in 2.6.0, are the preferred replacement.
  • 0e36dd6 Removed thread pools and SmartThreadPool dependency. The thread pool behavior (which was used to limit concurrency) uses semaphore-backed bulkheads introduced in 2.6.0. The removal of SmartThreadPool makes converting to .NET Core more manageable (see #16).
  • f83b511 Removed IStats and implementations. The preferred replacement is IMetricEvents.
  • 13320cc Made configuration injectable and removed dependency on Hudl.Config. There is currently no internal replacement for the actual config implementation. Would recommend using ASP.NET Core's Configuration API. See further details on configuration below and in the wiki.
  • 0edaaf2 871ab1c Removed dependency on Hudl.Common. Copied over the few classes (e.g. IClock, UtcSystemClock) that Mjolnir needs.
  • 5dd8295 Make logging injectable and remove dependency on log4net. There is currently no internal replacement for the actual logging implementation.
  • Removed CommandInvoker.Instance, it's an anti-pattern. Prefer to use DI to create and manage a singleton ICommandInvoker throughout your application.
  • e787e52 Moved the circuit breaker "ignored exceptions" (originally set statically on CommandContext) functionality to IBreakerExceptionHandler, which can be injected into CommandInvoker's constructor.
  • Removed ability to configure gauge intervals for metric events. Gauges now fire at a fixed 1000 ms interval; if a client is implementing IMetricEvents and handling gauge calls, the client should handle debouncing or otherwise aggregating the gauges at a less frequent resolution if desired.
  • 88642e9 Internally, CommandContext has been replaced with factory classes; there's no longer a static, central repository for state. Instead, the assumption is that the caller will only create a single CommandInvoker instance (via DI) and reuse it. Callers who need static access should consider creating a static singleton wrapper around a single instance of CommandInvoker. Docs will be updated to make it clear that only a single CommandInvoker should be used throughout an application.
  • 3fb1215 db6ae03 Removed Hudl.Mjolnir.Attributes and the reflective proxying helper classes. Clients can re-implement these if desired, but this 1) removes a dependency on Castle.Core, and 2) though convenient, fosters a pattern (using attributes) that makes code hard to unit test. We may bring this back in the future if it's needed, but if we do it'll be as a separate library instead of built into Mjolnir proper.
  • Convert project format to VS2017 csproj, and reorganize source into src/ and test/unit directories.
  • Mjolnir configuration re-write. It is based on strongly-typed classes now. IMjolnirConfig has been removed.
    To provide configuration into Mjolnir, it is required to instantiate MjolnirConfiguration class and pass it into Mjolnir objects. You should create one instance of this class only. Dependency injection pattern may be used in order to achieve this.
    If reading config from a file is required, an example implementation for JSON file has been provided in test project. See https://github.com/hudl/Mjolnir/pull/63/files#diff-1db9d5dd67e3c39c783fd9759d414387
    In order to update configuration, it is required to call NotifyAfterConfigUpdate on MjolnirConfiguration after any change to MjolnirConfiguration
  • IMjolnirLog interface modification, making it a generic type and adding the Debug(string) method. The IMjolnirLogFactory interface is updated too, making the CreateLog() method typed. The main reason being that it's easier to inject generic types with a DI system and since we we're always creating loggers with typeof(....), it made more sense to make the type generic and reduce the overhead of creating a Type object. See more details below on how to implement these interfaces below.
  • In Mjolnir 3.0.0 we're removing the hard dependency on log4net, and instead using logging interfaces, giving users of the library the chance to wire up the logging to their preferred implementation. The default implementation in the Mjolnir library is a no-op logger (see DefaultMjolnirLog and DefaultMjolnirLogFactory). Since the primary entry point to the Mjolnir library will be the CommandInvoker, you can pass in your own implementation of the IMjolnirLogFactory here.
  • Wiki documentation updated (right now it lives in Version3 branch in wiki project).

Removed / changed public APIs

Removed

  • Hudl.Mjolnir.Attributes CommandAttribute
  • Hudl.Mjolnir.Attributes CommandTimeoutAttribute
  • Hudl.Mjolnir.Attributes FireAndForgetAttribute
  • Hudl.Mjolnir.Command.Attribute CommandAttribute
  • Hudl.Mjolnir.Command.Attribute CommandTimeoutAttribute
  • Hudl.Mjolnir.Command.Attribute FireAndForgetAttribute
  • Hudl.Mjolnir.Command.Attribute CommandInterceptor
  • Hudl.Mjolnir ICommand
  • Hudl.Mjolnir Command<TResult>
  • Hudl.Mjolnir.Command Command
  • Hudl.Mjolnir.Command CommandCancelledException
  • Hudl.Mjolnir.Command CommandFailedException
  • Hudl.Mjolnir.Command CommandRejectedException
  • Hudl.Mjolnir.Command CommandTimeoutException
  • Hudl.Mjolnir.Command CommandContext
  • Hudl.Mjolnir.Command FallbackStatus
  • Hudl.Mjolnir.Command VoidResult
  • Hudl.Mjolnir.External IStats

Changed

  • Hudl.Mjolnir.Key GroupKey no longer has [Serializable] attribute
  • Hudl.Mjolnir.External IMetricEvents.BulkheadConfigGauge() is now BulkheadGauge() and has new parameters for the state of the bulkhead alongside the config values.
  • Hudl.Mjolnir.External IMetricEvents.BreakerConfigGauge() is now BreakerGauge() and has new parameters for the state of the breaker alongside the config values.
  • Breaker and Bulkhead names can no longer be named default - an exception will be thrown if they are. This is to avoid ambiguity with the default config properties.

Removed library dependencies

  • Hudl.Config
  • Hudl.Common
  • SmartThreadPool
  • log4net

Added public APIs

  • Hudl.Mjolnir.External IBreakerExceptionHandler
  • Hudl.Mjolnir.External IMjolnirLogFactory
  • Hudl.Mjolnir.External IMjolnirLog
  • Hudl.Mjolnir.Breaker IgnoredExceptionHandler
  • Hudl.Mjolnir.Config.MjolnirConfiguration MjolnirConfiguration - main class for Mjolnir configuration. Replaces IMjolnirConfig. Holds all configuration values.
  • Hudl.Mjolnir.Config.BreakerConfiguation BreakerConfiguation - configuration values for circuit breakers.
  • Hudl.Mjolnir.Config.BulkheadConfiguration BulkheadConfiguration - configuration values for bulkheads.
  • Hudl.Mjolnir.Config.CommandConfiguration CommandConfiguration - configuration values for commands.
Assets 2
Loading