adds OTelTraceIdRatioBasedSampler

Benchmarks/OTelTraceIdRatioBasedSamplerBenchmark/OTelTraceIdRatioBasedSamplerBenchmark.swift

@@ -0,0 +1,21 @@
+// Benchmark boilerplate generated by Benchmark
+
+import Benchmark
+import OTel
+
+let benchmarks = {
+    Benchmark("OTelTraceIdRatioBasedSampler") { benchmark in
+
+        let sampler = OTelTraceIdRatioBasedSampler(ratio: 0.5)
+        for _ in benchmark.scaledIterations {
+            _ = sampler.samplingResult(
+                operationName: "some-op",
+                kind: .internal,
+                traceID: .random(),
+                attributes: [:],
+                links: [],
+                parentContext: .topLevel)
+        }
+    }
+    // Add additional benchmarks here
+}

Package.swift

@@ -19,7 +19,9 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-nio.git", from: "2.0.0"),
         .package(url: "https://github.com/apple/swift-atomics.git", from: "1.0.2"),
         .package(url: "https://github.com/apple/swift-metrics.git", from: "2.4.1"),
-        .package(url: "https://github.com/slashmo/swift-w3c-trace-context.git", from: "1.0.0-beta.1"),
+        //.package(url: "https://github.com/slashmo/swift-w3c-trace-context.git", from: "1.0.0-beta.1"),
+        //.package(name: "swift-w3c-trace-context", path: "../swift-w3c-trace-context"),
+        .package(url: "https://github.com/t089/swift-w3c-trace-context.git", branch: "trace-id-bytes"),
 
         // MARK: - OTLP
 
@@ -30,6 +32,9 @@ let package = Package(
         // MARK: - Plugins
 
         .package(url: "https://github.com/apple/swift-docc-plugin.git", from: "1.0.0"),
+
+        // MARK: - Benchmarks
+        .package(url: "https://github.com/ordo-one/package-benchmark", .upToNextMajor(from: "1.4.0")),
     ],
     targets: [
         .target(
@@ -110,3 +115,18 @@ let package = Package(
     ],
     swiftLanguageVersions: [.version("6"), .v5]
 )
+
+// Benchmark of OTelTraceIdRatioBasedSamplerBenchmark
+package.targets += [
+    .executableTarget(
+        name: "OTelTraceIdRatioBasedSamplerBenchmark",
+        dependencies: [
+            .product(name: "Benchmark", package: "package-benchmark"),
+            "OTel",
+        ],
+        path: "Benchmarks/OTelTraceIdRatioBasedSamplerBenchmark",
+        plugins: [
+            .plugin(name: "BenchmarkPlugin", package: "package-benchmark")
+        ]
+    ),
+]

Sources/OTLPCore/Tracing/OTelFinishedSpan+Proto.swift

@@ -14,21 +14,22 @@
 import struct Foundation.Data
 import OTel
 import Tracing
+import W3CTraceContext
 
 extension Opentelemetry_Proto_Trace_V1_Span {
     /// Create a span from an `OTelFinishedSpan`.
     ///
     /// - Parameter finishedSpan: The `OTelFinishedSpan` to cast.
     public init(_ finishedSpan: OTelFinishedSpan) {
-        traceID = Data(finishedSpan.spanContext.traceID.bytes)
-        spanID = Data(finishedSpan.spanContext.spanID.bytes)
+        traceID = finishedSpan.spanContext.traceID.data
+        spanID = finishedSpan.spanContext.spanID.data
 
         if let traceStateHeaderValue = finishedSpan.spanContext.traceStateHeaderValue {
             self.traceState = traceStateHeaderValue
         }
 
         if let parentSpanID = finishedSpan.spanContext.parentSpanID {
-            self.parentSpanID = Data(parentSpanID.bytes)
+            self.parentSpanID = parentSpanID.data
         }
 
         name = finishedSpan.operationName
@@ -46,3 +47,19 @@ extension Opentelemetry_Proto_Trace_V1_Span {
         links = finishedSpan.links.compactMap(Opentelemetry_Proto_Trace_V1_Span.Link.init)
     }
 }
+
+extension TraceID {
+    var data: Data {
+        self.withUnsafeBytes {
+            Data($0)
+        }
+    }
+}
+
+extension SpanID {
+    var data: Data {
+        self.withUnsafeBytes {
+            Data($0)
+        }
+    }
+}

Sources/OTLPCore/Tracing/SpanLink+Proto.swift

@@ -21,8 +21,8 @@ extension Opentelemetry_Proto_Trace_V1_Span.Link {
     /// - Returns: `nil` if the `SpanLink`s context does not contain a span context.
     public init?(_ link: SpanLink) {
         guard let spanContext = link.context.spanContext else { return nil }
-        self.traceID = Data(spanContext.traceID.bytes)
-        self.spanID = Data(spanContext.spanID.bytes)
+        self.traceID = spanContext.traceID.data
+        self.spanID = spanContext.spanID.data
         if let traceStateHeaderValue = spanContext.traceStateHeaderValue {
             self.traceState = traceStateHeaderValue
         }

Sources/OTel/Tracing/Sampling/OTelTraceIdRatioBasedSampler.swift

@@ -0,0 +1,53 @@
+import Tracing
+import W3CTraceContext
+
+/// An `OTelSampler` based on a given `TraceID` and `ratio`.
+/// [Spec](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#traceidratiobased)
+public struct OTelTraceIdRatioBasedSampler: OTelSampler, Equatable, Hashable, CustomStringConvertible {
+
+    let idUpperBound : UInt64
+    public let ratio: Double
+
+    public init(ratio: Double) {
+        precondition(ratio >= 0.0 && ratio <= 1.0, "ratio must be between 0.0 and 1.0")
+
+        self.ratio = ratio
+        if ratio == 0.0 {
+            self.idUpperBound = .min
+        } else if ratio == 1.0 {
+            self.idUpperBound = .max
+        } else {
+            self.idUpperBound = UInt64(ratio * Double(UInt64.max))
+        }
+    }
+
+    public func samplingResult(
+        operationName: String,
+        kind: SpanKind,
+        traceID: TraceID,
+        attributes: SpanAttributes,
+        links: [SpanLink],
+        parentContext: ServiceContext
+    ) -> OTelSamplingResult {
+
+        let value = traceID.withUnsafeBytes { $0[8...].load(as: UInt64.self) }
+
+        if value < idUpperBound {
+            return .init(decision: .recordAndSample)
+        } else {
+            return .init(decision: .drop)
+        }
+    }
+
+    public static func ==(lhs: Self, rhs: Self) -> Bool {
+        lhs.idUpperBound == rhs.idUpperBound
+    }
+
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(self.idUpperBound)
+    }
+
+    public var description: String {
+        "TraceIdRatioBased{\(ratio)}"
+    }
+}

Tests/OTelTests/Tracing/Sampling/OTelTraceIdRatioBasedSamplerTests.swift

@@ -0,0 +1,70 @@
+@testable import OTel
+import XCTest
+import Tracing
+
+final class OTelTraceIdRatioBasedSamplerTests: XCTestCase {
+    func test_zero_ratio_does_not_sample() {
+        let sampler = OTelTraceIdRatioBasedSampler(ratio: 0.0)
+
+        let result = sampler.samplingResult(
+            operationName: "does-not-matter",
+            kind: .internal,
+            traceID: .allZeroes,
+            attributes: [:],
+            links: [],
+            parentContext: .topLevel
+        )
+
+        XCTAssertEqual(result, OTelSamplingResult(decision: .drop, attributes: [:]))
+    }
+
+    func test_one_ratio_does_sample() {
+        let sampler = OTelTraceIdRatioBasedSampler(ratio: 1.0)
+
+        let result = sampler.samplingResult(
+            operationName: "does-not-matter",
+            kind: .internal,
+            traceID: .allZeroes,
+            attributes: [:],
+            links: [],
+            parentContext: .topLevel
+        )
+
+        XCTAssertEqual(result, OTelSamplingResult(decision: .recordAndSample, attributes: [:]))
+    }
+
+
+    func test_different_ratios() {
+
+        let ratios = [0.0, 0.1, 0.25, 0.5, 0.75, 1.0]
+
+        for ratio in ratios {
+
+            let sampler = OTelTraceIdRatioBasedSampler(ratio: ratio)
+
+            let N = 100_000
+            var sampled = 0
+
+            for _ in 0 ..< N {
+                let result = sampler.samplingResult(
+                    operationName: "does-not-matter",
+                    kind: .internal,
+                    traceID: .random(),
+                    attributes: [:],
+                    links: [],
+                    parentContext: .topLevel
+                )
+
+                switch result.decision {
+                    case .recordAndSample:
+                        sampled += 1
+                    default: break
+                }
+            }
+
+            let observedRatio = Double(sampled) / Double(N)
+
+            XCTAssertEqual(ratio, observedRatio, accuracy: 0.05, "Expected ratio \(ratio) but observed \(observedRatio)")
+        }
+    }
+}