# Circuitbox 2.0 Upgrade Guide

## Requirements

Circuitbox 2.0 is tested against Ruby 2.6 through 3.2.
Since ruby 2.6 and 2.7 are EOL it's likely we'll drop support for those versions in future releases.

## Changes

* The `timeout_seconds` option when initializing a circuit has been removed.
  * Circuitbox does not wrap the block to run with Ruby's `Timeout` anymore.
    * If you would like to use Ruby's `Timeout` you would need to do this yourself.
* A `CircuitBreaker`'s `run` method has been changed and the `run!` method has been removed.
  * Calling `run` is now like calling `run!` in circuitbox 1.x.
  * If you were using `run` in circuitbox 1.x you can call `run(exception: false)` to have the same behavior.
* The `logger` option when initializing a circuit has been removed.
  * If you would like to use a logger you can either
    * If using the `ActiveSupport` notifier subscribe to it's notifications to add your own logger
    * Implement your own notifier using the same interface, see the `ActiveSupport` or `Null` notifier.
* The `exceptions` option when initializing a circuit must be an array.
* The `exceptions` option when initializing a circuit does not default to `[Timeout::Error]` when the array is empty.
* The `cache` option when initializing a circuit as been renamed to `circuit_store`.
* A circuits defaults sleep_window has changed from 300 seconds to 90 seconds.
* The `partition` option when running a circuit has been removed.
* attr_accessor's on `CircuitBreaker` have been changed to attr_reader, or in some cases removed.
  * `partition` has been removed
  * `logger` has been removed (see above about logger option)
  * `time_class` has been added
* The class level `reset` method on `Circuitbox` has been removed.
  * If you need to reset circuits before/after running a test you can reconfigure circuitbox
    ```ruby
        Circuitbox.configure do |config|
          # Reset persisted state in the memory store so it doesn't leak between tests
          # if using a store through moneta and want to reset it between tests you may need to do something else
          config.default_circuit_store = Circuitbox::MemoryStore.new
        end
    ```
* The class level `reset` method on `Circuitbox::CircuitBreaker` has been removed.
  * This method would call `reset` on `Circuitbox`, see above about `Circuitbox.reset`.
* `Circuitbox.circuit` does not parse a host name out of a uri and use that as the circuit's service_name.
  * If you rely on this functionality parse the host from the uri before calling `Circuitbox.circuit`
* Accessing/creating a circuit through `Circuitbox[:circuit_identifier]` has been removed.
* Circuitbox's notifications sent through `ActiveSupport::Notifications` have had their names changed.
  * `circuit_open` changes to `open.circuitbox`
  * `circuit_close` changes to `close.circuitbox`
  * `circuit_success` changes to `success.circuitbox`
  * `circuit_failure` changes to `failure.circuitbox`
  * `circuit_skipped` changes to `skipped.circuitbox`
  * `circuit_gauge` removed
  * `circuit_warning` changes to `warning.circuitbox`
  * add `run.circuitbox` to track runtime of the block the circuit is running
* Circuit's don't emit their error rate, success counts, failure counts through `ActiveSupport::Notifications` anymore.
  * The methods `error_rate`, `success_count`, `failure_count` on a circuit instance can be used to obtain this information.
* During circuit initialization if `sleep_window` is less than `time_window` it is not set to `time_window`.
  * Circuitbox warns about, and only checks this during circuit initialization
* Circuitbox's default circuit store has changed from `Moneta`'s memory store to `Circuitbox::MemoryStore`.
  * `Circuitbox::MemoryStore` periodically removes expired keys from the store, allowing Ruby to reclaim memory
  * When `Circuitbox::MemoryStore` is used a circuits time class is `Circuitbox::TimeHelper::Monotonic`
* If using `Moneta` as a circuit store, only adapters that support bulk read functionality are supported.