# Changelog
All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
## [Unreleased] - ReleaseDate
## [0.16.3] - 2024-03-16
### Added
- New set of methods on `Registry` for getting a metric handle if it exists. ([#457](https://github.com/metrics-rs/metrics/pull/457))
- New set of methods on `Registry` for retaining metric handles that match a given predicate. ([#461](https://github.com/metrics-rs/metrics/pull/461))
### Fixed
- Bump `ahash` back to `0.8.8` to remove range constraint after an upstream fix was provided to
remove the unnecessary MSRV bump.
## [0.16.2] - 2024-02-11
### Fixed
- Lock down the version of `ahash` to avoid unnecessary MSRV bumping.
## [0.16.1] - 2024-02-11
### Changed
- Bumped the `indexmap` and `hashbrown` dependencies to their latest versions. ([#438](https://github.com/metrics-rs/metrics/pull/438), [#439](https://github.com/metrics-rs/metrics/pull/439))
## [0.16.0] - 2023-12-24
### Fixed
- Fixed the `Debug` implementation for `bucket::Block<T>` which represented both an unsafe and
logically incorrect usage of `crossbeam-epoch.`
### Changed
- Bump MSRV to 1.65.0.
- `RecoverableRecorder` no longer functions as a drop guard itself, and instead returns a new
type, `RecoveryHandle<R>`, which provides that functionality. ([#414](https://github.com/metrics-rs/metrics/pull/414))
### Removed
- Support for per-thread mode in `DebuggingRecorder`. Users should now use
`metrics::with_local_recorder` instead, which is inherently per-thread.
## [0.15.1] - 2023-07-02
### Added
- Added a new helper type, `RecoverableRecorder`, that allows installing a recorder and then
recovering it later.
### Changed
- Update `aho-corasick` to `1.0`.
- Pinned `hashbrown` to `0.13.1` to avoid MSRV bump.
## [0.15.0] - 2023-04-16
### Changed
- Bump MSRV to 1.61.0.
- Switch to `metrics`-exposed version of `AtomicU64`.
## [0.14.0] - 2022-07-20
### Changed
- Updated `sketches-ddsketch` to `0.2.0`.
- Switched to using `portable_atomic` for 64-bit atomics on more architectures. (#313)
## [0.13.0] - 2022-05-30
### Fixed
- In `Summary`, some quantiles were previously mapped to an incorrect rank at low sample counts, leading to large swings
in estimated values. ([#304](https://github.com/metrics-rs/metrics/pull/304))
### Changed
- Bumped the dependency on `metrics` to deal with a public API change.
## [0.12.1] - 2022-05-02
### Added
- A new per-thread mode for `DebuggingRecorder` that allows recording metrics on a per-thread basis to better supporting
the testing of metrics in user applications where many tests are concurrently emitting metrics.
## [0.12.0] - 2022-03-10
### Added
- New storage type, `GenerationalStorage`, that provides the generational behavior of
`GenerationalAtomicStorage`, nee `GenerationalPrimitives`, without being inherently coupled to
using atomic storage.
### Changed
- Renamed `Primitives` to `Storage`, and publicly exposed it so that users can implement their own
storage strategies.
- Renamed `StandardPrimitives` and `GenerationalPrimitives` to `AtomicStorage` and
`GenerationalAtomicStorage`, respectively.
- Created a new top-level module, `registry`, that encompasses `Registry` and all `Registry`-related
and dependent types.
- Exposed `DefaultHashable` publicly.
- Debugging utilities have been moved to a new `debugging` module, and `Snapshot` is now public.
## [0.11.1] - 2022-02-20
### Fixed
- `Recency` incorrectly failed to keep track of the latest generation when a previously-observed
metric had changed generations since the first time it was observed.
## [0.11.0] - 2022-01-14
### Changed
- Updated various dependencies in order to properly scope dependencies to only the necessary feature
flags, and thus optimize build times and reduce transitive dependencies.
- Many types are now behind their own feature flags to allow for optimizing build times and
dependency tree.
- Updated to the new handle-based design of `metrics`.
- Updated `AtomicBucket` to use `MaybeUninit` and better documented the safety invariants in the
various areas that use `unsafe`.
- `AtomicBucket` now correctly drops only initialized slots in a `Block`.
## [0.10.2] - 2021-12-12
### Changed
- Bump `atomic-shim` from 0.1 to 0.2.
## [0.10.1] - 2021-09-16
### Changed
- Simple release to bump dependencies.
## [0.10.0] - 2021-07-13
### Changed
- Bumped `metrics` dependency to correspond to the change in key hasher.
## [0.9.1] - 2021-05-24
### Changed
- Pin `crossbeam-epoch` to the correct version where `Atomic::compare_exchange` support was added.
## [0.9.0] - 2021-05-19
### Changed
- Reworked `Registry` to make generation tracking a configurable property at the type level.
## [0.8.0] - 2021-05-18
### Added
- New layer -- `Router` -- for routing specific metrics to target downstream recorders.
- `Registry::clear` allows clearing all metrics from the registry.
### Changed
- Updated all deprecated usages of `crossbeam_epoch::Atomic<T>::compare_and_set` to `compare_exchange`.
## [0.7.0] - 2021-05-03
### Changed
- Switched `Registry` over to supporting `&Key`.
- Switched from `dashmap` to `hashbrown`/`parking_lot` for `Registry`.
- Updated all layers to support the change from `Key` to `&Key` in `metrics::Recorder`.`
### Added
- Support for using the pre-hashed value of `Key` to speed up `Registry` operations.
## [0.6.2] - 2021-03-08
### Changed
- Fixed issue with ordering on `CompositeKey`. (#182)
## [0.6.1] - 2021-02-07
### Added
- Added `AbsoluteLayer` for supporting counters reported via absolute value.
## [0.6.0] - 2021-02-02
### Changed
- Bumped `metrics` dependency to `0.14`.
## [0.5.0] - 2021-01-23
### Changed
- `MetricKind` is now `MetricKindMask`, and `MetricKind` is used to define the source side i.e.
`MetricKindMask` is used to match against `MetricKind`.
## [0.4.1] - 2021-01-22
- No changes.
## [0.4.0] - 2021-01-22
### Added
- Added multiple utility layers: prefix, filter, and fanout.
- Added `CompositeKey` for defining a metric kind/key combination.
- Added `Histogram` for defining a bucket-based histogram.
- Added `Registry` for storing metric handles mapped to a given key.
- Added `Summary`, based on DDSketch, as a more lightweight alternative to `hdrhistogram`.
- Added `DebuggingRecorder` to help tet various types that depend on a `Recorder`.
- Added `Recency` for tracking idle metrics.
### Removed
- Removed `StreamingIntegers` as we no longer use it, and `compressed_vec` is a better option.
- Removed `MetricsTree` as we no longer use it.
### Changed
- `AtomicBucket` now exposes `clear` and `clear_with` for both emptying the bucket and reading the
values that were cleared, allowing behavior similiar to atomically swapping a fresh data structure
in for another.
## [0.3.1] - 2019-11-21
### Changed
- Updated to crossbeam-epoch 0.8 and switched directly to crossbeam-utils for tests.
## [0.3.0] - 2019-04-30
### Added
- `MetricTree` allows storing hierarchical metric values while being serializable by serde. (#38)
## [0.2.1] - 2019-06-12
Erroneously bumped/published. No changes.
## [0.2.0] - 2019-06-11
### Added
- `StreamingIntegers` allows holding a set of integers in a compressed format in-memory. (#13)
- `AtomicBucket` provides an append-only list of items that can be snapshot without stopping writes. (#13)
## [0.1.0] - 2019-04-23
### Added
- Effective birth of the crate.