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adopt sendable (#109)
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motivation: adjust to swift 5.6

changes:
* define sendable shims for protocols and structs that may be used in async context
* refactor Gauge to include rather than inherit Recorder
* adjust tests
* add a test to make sure no warning are emitted
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@tomerd
tomerd authored Jul 1, 2022
1 parent fd0ee69 commit d885a4f
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Showing 8 changed files with 214 additions and 59 deletions.
83 changes: 59 additions & 24 deletions Sources/CoreMetrics/Metrics.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,9 @@
//
//===----------------------------------------------------------------------===//

// MARK: User API
// MARK: - User API

// MARK: - Counter

extension Counter {
/// Create a new `Counter`.
Expand All @@ -39,9 +41,9 @@ extension Counter {
/// This is the user-facing Counter API.
///
/// Its behavior depends on the `CounterHandler` implementation.
public class Counter {
public final class Counter {
@usableFromInline
var handler: CounterHandler
let handler: CounterHandler
public let label: String
public let dimensions: [(String, String)]

Expand Down Expand Up @@ -90,6 +92,8 @@ extension Counter: CustomStringConvertible {
}
}

// MARK: - FloatingPointCounter

extension FloatingPointCounter {
/// Create a new `FloatingPointCounter`.
///
Expand All @@ -116,9 +120,9 @@ extension FloatingPointCounter {
/// This is the user-facing FloatingPointCounter API.
///
/// Its behavior depends on the `FloatingCounterHandler` implementation.
public class FloatingPointCounter {
public final class FloatingPointCounter {
@usableFromInline
var handler: FloatingPointCounterHandler
let handler: FloatingPointCounterHandler
public let label: String
public let dimensions: [(String, String)]

Expand Down Expand Up @@ -167,21 +171,23 @@ extension FloatingPointCounter: CustomStringConvertible {
}
}

public extension Recorder {
// MARK: - Recorder

extension Recorder {
/// Create a new `Recorder`.
///
/// - parameters:
/// - label: The label for the `Recorder`.
/// - dimensions: The dimensions for the `Recorder`.
convenience init(label: String, dimensions: [(String, String)] = [], aggregate: Bool = true) {
public convenience init(label: String, dimensions: [(String, String)] = [], aggregate: Bool = true) {
let handler = MetricsSystem.factory.makeRecorder(label: label, dimensions: dimensions, aggregate: aggregate)
self.init(label: label, dimensions: dimensions, aggregate: aggregate, handler: handler)
}

/// Signal the underlying metrics library that this recorder will never be updated again.
/// In response the library MAY decide to eagerly release any resources held by this `Recorder`.
@inlinable
func destroy() {
public func destroy() {
MetricsSystem.factory.destroyRecorder(self.handler)
}
}
Expand All @@ -193,7 +199,7 @@ public extension Recorder {
/// Its behavior depends on the `RecorderHandler` implementation.
public class Recorder {
@usableFromInline
var handler: RecorderHandler
let handler: RecorderHandler
public let label: String
public let dimensions: [(String, String)]
public let aggregate: Bool
Expand Down Expand Up @@ -247,10 +253,12 @@ extension Recorder: CustomStringConvertible {
}
}

// MARK: - Gauge

/// A gauge is a metric that represents a single numerical value that can arbitrarily go up and down.
/// Gauges are typically used for measured values like temperatures or current memory usage, but also "counts" that can go up and down, like the number of active threads.
/// Gauges are modeled as `Recorder` with a sample size of 1 and that does not perform any aggregation.
public class Gauge: Recorder {
public final class Gauge: Recorder {
/// Create a new `Gauge`.
///
/// - parameters:
Expand All @@ -261,6 +269,8 @@ public class Gauge: Recorder {
}
}

// MARK: - Timer

public struct TimeUnit: Equatable {
private enum Code: Equatable {
case nanoseconds
Expand Down Expand Up @@ -328,9 +338,9 @@ public extension Timer {
/// This is the user-facing Timer API.
///
/// Its behavior depends on the `TimerHandler` implementation.
public class Timer {
public final class Timer {
@usableFromInline
var handler: TimerHandler
let handler: TimerHandler
public let label: String
public let dimensions: [(String, String)]

Expand Down Expand Up @@ -451,6 +461,8 @@ extension Timer: CustomStringConvertible {
}
}

// MARK: - MetricsSystem

/// The `MetricsSystem` is a global facility where the default metrics backend implementation (`MetricsFactory`) can be
/// configured. `MetricsSystem` is set up just once in a given program to set up the desired metrics backend
/// implementation.
Expand All @@ -459,7 +471,7 @@ public enum MetricsSystem {

/// `bootstrap` is an one-time configuration function which globally selects the desired metrics backend
/// implementation. `bootstrap` can be called at maximum once in any given program, calling it more than once will
/// lead to undefined behaviour, most likely a crash.
/// lead to undefined behavior, most likely a crash.
///
/// - parameters:
/// - factory: A factory that given an identifier produces instances of metrics handlers such as `CounterHandler`, `RecorderHandler` and `TimerHandler`.
Expand Down Expand Up @@ -514,7 +526,9 @@ public enum MetricsSystem {
}
}

// MARK: Library SPI, intended to be implemented by backend libraries
// MARK: - Library SPI, intended to be implemented by backend libraries

// MARK: - MetricsFactory

/// The `MetricsFactory` is the bridge between the `MetricsSystem` and the metrics backend implementation.
/// `MetricsFactory`'s role is to initialize concrete implementations of the various metric types:
Expand Down Expand Up @@ -601,7 +615,7 @@ public protocol MetricsFactory {
}

/// Wraps a CounterHandler, adding support for incrementing by floating point values by storing an accumulated floating point value and recording increments to the underlying CounterHandler after crossing integer boundaries.
internal class AccumulatingRoundingFloatingPointCounter: FloatingPointCounterHandler {
internal final class AccumulatingRoundingFloatingPointCounter: FloatingPointCounterHandler {
private let lock = Lock()
private let counterHandler: CounterHandler
internal var fraction: Double = 0
Expand Down Expand Up @@ -689,6 +703,8 @@ extension MetricsFactory {
}
}

// MARK: - Backend Handlers

/// A `CounterHandler` represents a backend implementation of a `Counter`.
///
/// This type is an implementation detail and should not be used directly, unless implementing your own metrics backend.
Expand All @@ -700,7 +716,7 @@ extension MetricsFactory {
/// as expected regardless of the selected `CounterHandler` implementation.
///
/// - The `CounterHandler` must be a `class`.
public protocol CounterHandler: AnyObject {
public protocol CounterHandler: AnyObject, _SwiftMetricsSendableProtocol {
/// Increment the counter.
///
/// - parameters:
Expand All @@ -722,7 +738,7 @@ public protocol CounterHandler: AnyObject {
/// as expected regardless of the selected `FloatingPointCounterHandler` implementation.
///
/// - The `FloatingPointCounterHandler` must be a `class`.
public protocol FloatingPointCounterHandler: AnyObject {
public protocol FloatingPointCounterHandler: AnyObject, _SwiftMetricsSendableProtocol {
/// Increment the counter.
///
/// - parameters:
Expand All @@ -744,7 +760,7 @@ public protocol FloatingPointCounterHandler: AnyObject {
/// as expected regardless of the selected `RecorderHandler` implementation.
///
/// - The `RecorderHandler` must be a `class`.
public protocol RecorderHandler: AnyObject {
public protocol RecorderHandler: AnyObject, _SwiftMetricsSendableProtocol {
/// Record a value.
///
/// - parameters:
Expand All @@ -768,7 +784,7 @@ public protocol RecorderHandler: AnyObject {
/// as expected regardless of the selected `TimerHandler` implementation.
///
/// - The `TimerHandler` must be a `class`.
public protocol TimerHandler: AnyObject {
public protocol TimerHandler: AnyObject, _SwiftMetricsSendableProtocol {
/// Record a duration in nanoseconds.
///
/// - parameters:
Expand All @@ -788,7 +804,7 @@ extension TimerHandler {
}
}

// MARK: Predefined Metrics Handlers
// MARK: - Predefined Metrics Handlers

/// A pseudo-metrics handler that can be used to send messages to multiple other metrics handlers.
public final class MultiplexMetricsHandler: MetricsFactory {
Expand Down Expand Up @@ -837,7 +853,7 @@ public final class MultiplexMetricsHandler: MetricsFactory {
}
}

private class MuxCounter: CounterHandler {
private final class MuxCounter: CounterHandler {
let counters: [CounterHandler]
public init(factories: [MetricsFactory], label: String, dimensions: [(String, String)]) {
self.counters = factories.map { $0.makeCounter(label: label, dimensions: dimensions) }
Expand All @@ -852,7 +868,7 @@ public final class MultiplexMetricsHandler: MetricsFactory {
}
}

private class MuxFloatingPointCounter: FloatingPointCounterHandler {
private final class MuxFloatingPointCounter: FloatingPointCounterHandler {
let counters: [FloatingPointCounterHandler]
public init(factories: [MetricsFactory], label: String, dimensions: [(String, String)]) {
self.counters = factories.map { $0.makeFloatingPointCounter(label: label, dimensions: dimensions) }
Expand All @@ -867,7 +883,7 @@ public final class MultiplexMetricsHandler: MetricsFactory {
}
}

private class MuxRecorder: RecorderHandler {
private final class MuxRecorder: RecorderHandler {
let recorders: [RecorderHandler]
public init(factories: [MetricsFactory], label: String, dimensions: [(String, String)], aggregate: Bool) {
self.recorders = factories.map { $0.makeRecorder(label: label, dimensions: dimensions, aggregate: aggregate) }
Expand All @@ -882,7 +898,7 @@ public final class MultiplexMetricsHandler: MetricsFactory {
}
}

private class MuxTimer: TimerHandler {
private final class MuxTimer: TimerHandler {
let timers: [TimerHandler]
public init(factories: [MetricsFactory], label: String, dimensions: [(String, String)]) {
self.timers = factories.map { $0.makeTimer(label: label, dimensions: dimensions) }
Expand Down Expand Up @@ -928,3 +944,22 @@ public final class NOOPMetricsHandler: MetricsFactory, CounterHandler, FloatingP
public func record(_: Double) {}
public func recordNanoseconds(_: Int64) {}
}

// MARK: - Sendable support helpers

#if compiler(>=5.6)
extension MetricsSystem: Sendable {}
extension Counter: Sendable {}
extension FloatingPointCounter: Sendable {}
// must be @unchecked since Gauge inherits Recorder :(
extension Recorder: @unchecked Sendable {}
extension Timer: Sendable {}
// ideally we would not be using @unchecked here, but concurrency-safety checks do not recognize locks
extension AccumulatingRoundingFloatingPointCounter: @unchecked Sendable {}
#endif

#if compiler(>=5.6)
@preconcurrency public protocol _SwiftMetricsSendableProtocol: Sendable {}
#else
public protocol _SwiftMetricsSendableProtocol {}
#endif
12 changes: 6 additions & 6 deletions Sources/Metrics/Metrics.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -16,15 +16,15 @@
@_exported import class CoreMetrics.Timer
import Foundation

public extension Timer {
extension Timer {
/// Convenience for measuring duration of a closure.
///
/// - parameters:
/// - label: The label for the Timer.
/// - dimensions: The dimensions for the Timer.
/// - body: Closure to run & record.
@inlinable
static func measure<T>(label: String, dimensions: [(String, String)] = [], body: @escaping () throws -> T) rethrows -> T {
public static func measure<T>(label: String, dimensions: [(String, String)] = [], body: @escaping () throws -> T) rethrows -> T {
let timer = Timer(label: label, dimensions: dimensions)
let start = DispatchTime.now().uptimeNanoseconds
defer {
Expand All @@ -39,18 +39,18 @@ public extension Timer {
/// - parameters:
/// - since: Start of the interval as `DispatchTime`.
/// - end: End of the interval, defaulting to `.now()`.
func recordInterval(since: DispatchTime, end: DispatchTime = .now()) {
public func recordInterval(since: DispatchTime, end: DispatchTime = .now()) {
self.recordNanoseconds(end.uptimeNanoseconds - since.uptimeNanoseconds)
}
}

public extension Timer {
extension Timer {
/// Convenience for recording a duration based on TimeInterval.
///
/// - parameters:
/// - duration: The duration to record.
@inlinable
func record(_ duration: TimeInterval) {
public func record(_ duration: TimeInterval) {
self.recordSeconds(duration)
}

Expand All @@ -59,7 +59,7 @@ public extension Timer {
/// - parameters:
/// - duration: The duration to record.
@inlinable
func record(_ duration: DispatchTimeInterval) {
public func record(_ duration: DispatchTimeInterval) {
switch duration {
case .nanoseconds(let value):
self.recordNanoseconds(value)
Expand Down
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