Merge pull request #4 from MrLotU/MetricsLib

Implement swift-metrics

Author: MrLotU

.gitignore

@@ -2,4 +2,5 @@
 /.build
 /Packages
 /*.xcodeproj
-build/
+build/
+.swiftpm/

.travis.yml

@@ -9,15 +9,22 @@ let package = Package(
             name: "SwiftPrometheus",
             targets: ["Prometheus"]),
     ],
+    dependencies: [
+        .package(url: "https://github.com/apple/swift-metrics.git", from: "1.0.0"),
+        .package(url: "https://github.com/apple/swift-nio.git", Version("1.0.0") ..< Version("3.0.0")),
+    ],
     targets: [
         .target(
             name: "Prometheus",
-            dependencies: []),
+            dependencies: ["NIOConcurrencyHelpers"]),
+        .target(
+            name: "PrometheusMetrics",
+            dependencies: ["Prometheus", "CoreMetrics"]),
         .target(
             name: "PrometheusExample",
-            dependencies: ["Prometheus"]),
+            dependencies: ["PrometheusMetrics", "Metrics"]),
         .testTarget(
             name: "SwiftPrometheusTests",
-            dependencies: ["Prometheus"]),
+            dependencies: ["Prometheus", "PrometheusMetrics"]),
     ]
 )

Package.resolved

@@ -1,4 +1,4 @@
-[![Build Status](https://travis-ci.com/MrLotU/SwiftPrometheus.svg?branch=master)](https://travis-ci.com/MrLotU/SwiftPrometheus) [![Swift 5.0](https://img.shields.io/badge/swift-5.0-orange.svg?style=flat)](http://swift.org)
+[![CircleCI](https://circleci.com/gh/MrLotU/SwiftPrometheus.svg?style=svg)](https://circleci.com/gh/MrLotU/SwiftPrometheus)[![Swift 5.0](https://img.shields.io/badge/swift-5.0-orange.svg?style=flat)](http://swift.org)
 
 # SwiftPrometheus, Prometheus client for Swift
 
@@ -8,14 +8,35 @@ A prometheus client for Swift supporting counters, gauges, histograms, summaries
 
 For examples, see [main.swift](./Sources/PrometheusExample/main.swift)
 
+First, we have to create an instance of our `PrometheusClient`:
+```swift
+import Prometheus
+let myProm = PrometheusClient()
+```
+
+## Usage with Swift-Metrics
+_For more details about swift-metrics, check the GitHub repo [here](https://github.com/apple/swift-metrics)_
+
+To use SwiftPrometheus with swift-metrics, all the setup required is this:
+```swift
+import PrometheusMetrics // Auto imports Prometheus too, but adds the swift-metrics compatibility
+let myProm = PrometheusClient()
+MetricsSystem.bootstrap(myProm)
+```
+
+To use prometheus specific features in a later stage of your program, or to get your metrics out of the system, there is a convenience method added to `MetricsSystem`:
+```swift
+// This is the same instance was used in `.bootstrap()` earlier.
+let promInstance = try MetricsSystem.prometheus()
+```
+You can than use the same APIs that are layed out in the rest of this README
+
 ## Counter
 
 Counters go up, and reset when the process restarts.
 
 ```swift
-let prom = PrometheusClient()
-
-let counter = prom.createCounter(forType: Int.self, named: "my_counter")
+let counter = myProm.createCounter(forType: Int.self, named: "my_counter")
 counter.inc() // Increment by 1
 counter.inc(12) // Increment by given value 
 ```
@@ -25,9 +46,7 @@ counter.inc(12) // Increment by given value
 Gauges can go up and down
 
 ```swift
-let prom = PrometheusClient()
-
-let gauge = prom.createGauge(forType: Int.self, named: "my_gauge")
+let gauge = myProm.createGauge(forType: Int.self, named: "my_gauge")
 gauge.inc() // Increment by 1
 gauge.dec(19) // Decrement by given value
 gauge.set(12) // Set to a given value
@@ -38,9 +57,7 @@ gauge.set(12) // Set to a given value
 Histograms track the size and number of events in buckets. This allows for aggregatable calculation of quantiles.
 
 ```swift
-let prom = PrometheusClient()
-
-let histogram = prom.createHistogram(forType: Double.self, named: "my_histogram")
+let histogram = myProm.createHistogram(forType: Double.self, named: "my_histogram")
 histogram.observe(4.7) // Observe the given value
 ```
 
@@ -49,9 +66,7 @@ histogram.observe(4.7) // Observe the given value
 Summaries track the size and number of events
 
 ```swift
-let prom = PrometheusClient()
-
-let summary = prom.createSummary(forType: Double.self, named: "my_summary")
+let summary = myProm.createSummary(forType: Double.self, named: "my_summary")
 summary.observe(4.7) // Observe the given value
 ```
 
@@ -72,7 +87,7 @@ struct MyInfoStruct: MetricLabels {
    }
 }
 
-let prom = PrometheusClient()
+let info = myProm.createInfo(named: "my_info", helpText: "Just some info", labelType: MyInfoStruct.self)
 
 let info = prom.createInfo(named: "my_info", helpText: "Just some info", labelType: MyInfoStruct.self)
 
@@ -88,7 +103,7 @@ struct RouteLabels: MetricLabels {
    var route: String = "*"
 }
 
-let prom = PrometheusClient()
+let counter = myProm.createCounter(forType: Int.self, named: "my_counter", helpText: "Just a counter", withLabelType: RouteLabels.self)
 
 let counter = prom.createCounter(forType: Int.self, named: "my_counter", helpText: "Just a counter", withLabelType: RouteLabels.self)
 
@@ -101,12 +116,8 @@ To keep SwiftPrometheus as clean and lightweight as possible, there is no way of
 
 This could look something like this:
 ```swift
-router.get("/metrics") { request -> Future<String> in
-    let promise = req.eventLoop.newPromise(String.self)
-    prom.getMetrics {
-        promise.succeed(result: $0)
-    }
-    return promise.futureResult
+router.get("/metrics") { request -> String in
+    return myProm.collect()
 }
 ```
 Here, I used [Vapor](https://github.com/vapor/vapor) syntax, but this will work with any web framework, since it's just returning a plain String.

Package.swift

@@ -1,27 +1,32 @@
+import NIOConcurrencyHelpers
+
 /// Prometheus Counter metric
 ///
-/// See https://prometheus.io/docs/concepts/metric_types/#counter
-public class Counter<NumType: Numeric, Labels: MetricLabels>: Metric, PrometheusHandled {
+/// See: https://prometheus.io/docs/concepts/metric_types/#counter
+public class PromCounter<NumType: Numeric, Labels: MetricLabels>: PromMetric, PrometheusHandled {
     /// Prometheus instance that created this Counter
-    internal let prometheus: PrometheusClient
+    internal weak var prometheus: PrometheusClient?
 
     /// Name of the Counter, required
     public let name: String
     /// Help text of the Counter, optional
     public let help: String?
 
     /// Type of the metric, used for formatting
-    public let _type: MetricType = .counter
+    public let _type: PromMetricType = .counter
 
     /// Current value of the counter
     internal var value: NumType
 
     /// Initial value of the counter
-    private var initialValue: NumType
+    private let initialValue: NumType
 
     /// Storage of values that have labels attached
     internal var metrics: [Labels: NumType] = [:]
 
+    /// Lock used for thread safety
+    internal let lock: Lock
+    
     /// Creates a new instance of a Counter
     ///
     /// - Parameters:
@@ -35,14 +40,15 @@ public class Counter<NumType: Numeric, Labels: MetricLabels>: Metric, Prometheus
         self.initialValue = initialValue
         self.value = initialValue
         self.prometheus = p
+        self.lock = Lock()
     }
 
     /// Gets the metric string for this counter
     ///
     /// - Returns:
     ///     Newline seperated Prometheus formatted metric string
-    public func getMetric(_ done: @escaping (String) -> Void) {
-        prometheusQueue.async(flags: .barrier) {
+    public func collect() -> String {
+        return self.lock.withLock {
             var output = [String]()
 
             if let help = self.help {
@@ -57,26 +63,28 @@ public class Counter<NumType: Numeric, Labels: MetricLabels>: Metric, Prometheus
                 output.append("\(self.name)\(labelsString) \(value)")
             }
 
-            done(output.joined(separator: "\n"))
+            return output.joined(separator: "\n")
         }
     }
 
+    
     /// Increments the Counter
     ///
     /// - Parameters:
     ///     - amount: Amount to increment the counter with
     ///     - labels: Labels to attach to the value
     ///
-    public func inc(_ amount: NumType = 1, _ labels: Labels? = nil, _ done: @escaping (NumType) -> Void = { _ in }) {
-        prometheusQueue.async(flags: .barrier) {
+    @discardableResult
+    public func inc(_ amount: NumType = 1, _ labels: Labels? = nil) -> NumType {
+        return self.lock.withLock {
             if let labels = labels {
                 var val = self.metrics[labels] ?? self.initialValue
                 val += amount
                 self.metrics[labels] = val
-                done(val)
+                return val
             } else {
                 self.value += amount
-                done(self.value)
+                return self.value
             }
         }
     }
@@ -88,10 +96,12 @@ public class Counter<NumType: Numeric, Labels: MetricLabels>: Metric, Prometheus
     ///
     /// - Returns: The value of the Counter attached to the provided labels
     public func get(_ labels: Labels? = nil) -> NumType {
-        if let labels = labels {
-            return self.metrics[labels] ?? initialValue
-        } else {
-            return self.value
+        return self.lock.withLock {
+            if let labels = labels {
+                return self.metrics[labels] ?? initialValue
+            } else {
+                return self.value
+            }
         }
     }
 }