Index the QPACK static table by name

Benchmarks/Package.swift

@@ -0,0 +1,44 @@
+// swift-tools-version:6.3
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftNIO open source project
+//
+// Copyright (c) 2026 Apple Inc. and the SwiftNIO project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import PackageDescription
+
+let package = Package(
+    name: "swift-nio-http3-benchmarks",
+    platforms: [
+        .macOS(.v13)
+    ],
+    dependencies: [
+        .package(path: "../"),
+        .package(url: "https://github.com/apple/swift-http-types.git", from: "1.3.0"),
+        .package(url: "https://github.com/apple/swift-nio-quic-helpers.git", branch: "main"),
+        .package(url: "https://github.com/ordo-one/benchmark.git", from: "1.35.0"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "QPACKBenchmarks",
+            dependencies: [
+                .product(name: "NIOHTTP3", package: "swift-nio-http3"),
+                .product(name: "HTTPTypes", package: "swift-http-types"),
+                .product(name: "NIOQUICHelpers", package: "swift-nio-quic-helpers"),
+                .product(name: "Benchmark", package: "benchmark"),
+            ],
+            path: "QPACKBenchmarks",
+            plugins: [
+                .plugin(name: "BenchmarkPlugin", package: "benchmark")
+            ]
+        )
+    ]
+)

Benchmarks/QPACKBenchmarks/QPACKBenchmarks.swift

@@ -0,0 +1,73 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftNIO open source project
+//
+// Copyright (c) 2026 Apple Inc. and the SwiftNIO project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Benchmark
+import HTTPTypes
+@_spi(Benchmarks) import NIOHTTP3
+import NIOQUICHelpers
+
+/// A realistic request header set for a browser GET, exercising a mix of exact
+/// static-table matches (`:method GET`), name-only matches (`:authority`) and
+/// headers absent from the table (`x-custom-header`).
+private let requestHeaders: [HTTPField] = [
+    HTTPField(name: .init(parsed: ":method")!, value: "GET"),
+    HTTPField(name: .init(parsed: ":scheme")!, value: "https"),
+    HTTPField(name: .init(parsed: ":authority")!, value: "www.example.com"),
+    HTTPField(name: .init(parsed: ":path")!, value: "/index.html"),
+    HTTPField(name: .init(parsed: "user-agent")!, value: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)"),
+    HTTPField(name: .init(parsed: "accept")!, value: "*/*"),
+    HTTPField(name: .init(parsed: "accept-encoding")!, value: "gzip, deflate, br"),
+    HTTPField(name: .init(parsed: "accept-language")!, value: "en-US,en;q=0.9"),
+    HTTPField(name: .init(parsed: "cache-control")!, value: "no-cache"),
+    HTTPField(name: .init(parsed: "cookie")!, value: "session=abc123def456; theme=dark"),
+    HTTPField(name: .init(parsed: "referer")!, value: "https://www.example.com/"),
+    HTTPField(name: .init(parsed: "x-custom-header")!, value: "some-custom-value"),
+]
+
+let benchmarks: @Sendable () -> Void = {
+    // Exercises StaticHeaderTable.find on every header, with no dynamic table.
+    Benchmark(
+        "QPACKStaticEncode_BrowserGET",
+        configuration: .init(
+            metrics: [.mallocCountTotal, .instructions, .wallClock],
+            scalingFactor: .kilo
+        )
+    ) { benchmark in
+        for _ in benchmark.scaledIterations {
+            blackHole(QPACKBenchmarks.staticEncode(headers: requestHeaders))
+        }
+    }
+
+    // Exercises the static-table lookup plus the dynamic table on every header.
+    Benchmark(
+        "QPACKDynamicEncode_BrowserGET",
+        configuration: .init(
+            metrics: [.mallocCountTotal, .instructions, .wallClock],
+            scalingFactor: .kilo
+        )
+    ) { benchmark in
+        for _ in benchmark.scaledIterations {
+            blackHole(
+                QPACKBenchmarks.dynamicEncode(
+                    headers: requestHeaders,
+                    streamID: QUICStreamID(rawValue: 0),
+                    dynamicTableMaxCapacity: 4096,
+                    dynamicTableInitialCapacity: 4096,
+                    maxBlockedStreams: 100,
+                    targetEvictableFraction: 0.5
+                )
+            )
+        }
+    }
+}

Sources/NIOHTTP3/QPACK+SPI.swift

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftNIO open source project
+//
+// Copyright (c) 2026 Apple Inc. and the SwiftNIO project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+public import HTTPTypes
+public import NIOQUICHelpers
+private import QPACK
+
+// QPACK isn't a library product, so add entry points for benchmarks here under SPI.
+@_spi(Benchmarks)
+public enum QPACKBenchmarks {
+    /// Encode `headers` with the static-only encoder. Returns the number of field lines
+    /// produced.
+    ///
+    /// The return value doesn't matter, but needs to be there so the calling benchmark
+    /// can stop the function call from being optimised away.
+    @_spi(Benchmarks)
+    public static func staticEncode(headers: [HTTPField]) -> Int {
+        let encoder = StaticQPACKEncoder()
+        return encoder.encode(headers: headers).lines.count
+    }
+
+    /// Create a dynamic encoder and encode `headers` on `streamID`. Returns the number
+    /// of field lines produced.
+    ///
+    /// The return value doesn't matter, but needs to be there so the calling benchmark
+    /// can stop the function call from being optimised away.
+    @_spi(Benchmarks)
+    public static func dynamicEncode(
+        headers: [HTTPField],
+        streamID: QUICStreamID,
+        dynamicTableMaxCapacity: Int,
+        dynamicTableInitialCapacity: Int,
+        maxBlockedStreams: Int,
+        targetEvictableFraction: Double
+    ) -> Int {
+        var (encoder, _) = DynamicQPACKEncoder.create(
+            dynamicTableMaxCapacity: dynamicTableMaxCapacity,
+            dynamicTableInitialCapacity: dynamicTableInitialCapacity,
+            maxBlockedStreams: maxBlockedStreams,
+            targetEvictableFraction: targetEvictableFraction
+        )
+        return encoder.encode(headers: headers, forStream: streamID).fieldSection.lines.count
+    }
+}

Sources/QPACK/Headers/StaticHeaderTable.swift

@@ -121,6 +121,16 @@ package enum StaticHeaderTable {
         (.init(parsed: "x-frame-options")!, "sameorigin"),  // 98
     ]
 
+    /// A mapping of header name to the array of static table indices carrying that name.
+    /// Array are guaranteed to be non-empty, and their values are in ascending index order.
+    private static let indicesByName: [HTTPField.Name: [Int]] = {
+        var result = [HTTPField.Name: [Int]](minimumCapacity: Self.shared.count)
+        for index in Self.shared.indices {
+            result[Self.shared[index].0, default: []].append(index)
+        }
+        return result
+    }()
+
     /// Get the element of the static table at the specific index if it exists
     package static func get(at index: Int) -> (HTTPField.Name, String)? {
         if self.shared.indices.contains(index) {
@@ -143,21 +153,19 @@ package enum StaticHeaderTable {
     ///            parameter, an indication whether that value was also found. Returns `nil`
     ///            if no matching header name could be located.
     static func find(name: HTTPField.Name, value: String?) -> (index: Int, containsValue: Bool)? {
-        var nameOnlyMatchIndex: Int?
-        for index in Self.shared.indices {
-            let header = Self.shared[index]
-            if header.0 == name {
-                if header.1 == value {
+        guard let indices = Self.indicesByName[name] else {
+            return nil
+        }
+
+        if let value = value {
+            for index in indices {
+                if Self.shared[index].1 == value {
                     return (index: index, containsValue: true)
-                } else if nameOnlyMatchIndex == nil {
-                    nameOnlyMatchIndex = index
                 }
             }
         }
-        if let nameOnlyMatchIndex {
-            return (index: nameOnlyMatchIndex, containsValue: false)
-        } else {
-            return nil
-        }
+
+        // No value (or no matching value), return the first index.
+        return (index: indices[0], containsValue: false)
     }
 }