feat: Add fetch_metrics() for HTTP connection managers (#273)

Co-authored-by: Steven Yuan <yuasteve@amazon.com>
Co-authored-by: Dengke Tang <815825145@qq.com>

Package.swift

@@ -38,6 +38,10 @@ awsCCommonPlatformExcludes.append("source/arch/arm")
 #if !os(Windows)
 awsCCommonPlatformExcludes.append("source/windows")
 #endif
+let cSettingsCommon: [CSetting] = [
+    .headerSearchPath("source/external/libcbor"),
+    .define("DEBUG_BUILD", .when(configuration: .debug))
+]
 
 //////////////////////////////////////////////////////////////////////
 /// aws-c-cal
@@ -198,7 +202,7 @@ packageTargets.append(contentsOf: [
         dependencies: ["AwsCPlatformConfig"],
         path: "aws-common-runtime/aws-c-common",
         exclude: awsCCommonPlatformExcludes,
-        cSettings: cSettings
+        cSettings: cSettingsCommon
     ),
     .target(
         name: "AwsCSdkUtils",

Source/AwsCommonRuntimeKit/http/HTTP2StreamManager.swift

@@ -42,6 +42,17 @@ public class HTTP2StreamManager {
         })
     }
 
+    /// Fetch the current manager metrics from connection manager.
+    public func fetchMetrics() -> HTTPClientConnectionManagerMetrics {
+        var cManagerMetrics = aws_http_manager_metrics()
+        aws_http2_stream_manager_fetch_metrics(rawValue, &cManagerMetrics)
+        return HTTPClientConnectionManagerMetrics(
+            availableConcurrency: cManagerMetrics.available_concurrency,
+            pendingConcurrencyAcquires: cManagerMetrics.pending_concurrency_acquires,
+            leasedConcurrency: cManagerMetrics.leased_concurrency
+        )
+    }
+
     deinit {
         aws_http2_stream_manager_release(rawValue)
     }

Source/AwsCommonRuntimeKit/http/HTTPClientConnectionManager.swift

@@ -39,6 +39,17 @@ public class HTTPClientConnectionManager {
         }
     }
 
+    /// Fetch the current manager metrics from connection manager.
+    public func fetchMetrics() -> HTTPClientConnectionManagerMetrics {
+        var cManagerMetrics = aws_http_manager_metrics()
+        aws_http_connection_manager_fetch_metrics(rawValue, &cManagerMetrics)
+        return HTTPClientConnectionManagerMetrics(
+            availableConcurrency: cManagerMetrics.available_concurrency,
+            pendingConcurrencyAcquires: cManagerMetrics.pending_concurrency_acquires,
+            leasedConcurrency: cManagerMetrics.leased_concurrency
+        )
+    }
+
     deinit {
         aws_http_connection_manager_release(rawValue)
     }

Source/AwsCommonRuntimeKit/http/HTTPClientConnectionManagerMetrics.swift

@@ -0,0 +1,26 @@
+//  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//  SPDX-License-Identifier: Apache-2.0.
+
+public struct HTTPClientConnectionManagerMetrics {
+    /// The number of additional concurrent requests that can be supported by the HTTP manager without needing to
+    /// establish additional connections to the target server.
+    ///
+    /// For connection manager, it equals to connections that's idle.
+    /// For stream manager, it equals to the number of streams that are possible to be made without creating new
+    /// connection, although the implementation can create new connection without fully filling it.
+    public var availableConcurrency: Int
+    /// The number of requests that are awaiting concurrency to be made available from the HTTP manager.
+    public var pendingConcurrencyAcquires: Int
+    /// The number of connections (HTTP/1.1) or streams (for HTTP/2 via. stream manager) currently vended to user.
+    public var leasedConcurrency: Int
+
+    public init(
+        availableConcurrency: Int,
+        pendingConcurrencyAcquires: Int,
+        leasedConcurrency: Int
+    ) {
+        self.availableConcurrency = availableConcurrency
+        self.pendingConcurrencyAcquires = pendingConcurrencyAcquires
+        self.leasedConcurrency = leasedConcurrency
+    }
+}

Test/AwsCommonRuntimeKitTests/http/HTTP2StreamManagerTests.swift

@@ -125,6 +125,9 @@ class HTT2StreamManagerTests: HTTPClientTestFixture {
 
         let stream = try await streamManager.acquireStream(requestOptions: http2RequestOptions)
         XCTAssertFalse(onCompleteCalled)
+        let metrics = streamManager.fetchMetrics()
+        XCTAssertTrue(metrics.availableConcurrency > 0)
+        XCTAssertTrue(metrics.leasedConcurrency > 0)
         let data = TEST_DOC_LINE.data(using: .utf8)!
         for chunk in data.chunked(into: 5) {
             try await stream.writeChunk(chunk: chunk, endOfStream: false)

Test/AwsCommonRuntimeKitTests/http/HTTPTests.swift

@@ -15,7 +15,7 @@ class HTTPTests: HTTPClientTestFixture {
         _ = try await sendHTTPRequest(method: "GET", endpoint: host, path: getPath, connectionManager: connectionManager)
         _ = try await sendHTTPRequest(method: "GET", endpoint: host, path: "/delete", expectedStatus: 404, connectionManager: connectionManager)
     }
-    
+
     func testGetHTTPSRequestWithUtf8Header() async throws {
         let connectionManager = try await getHttpConnectionManager(endpoint: host, ssh: true, port: 443)
         let utf8Header = HTTPHeader(name: "TestHeader", value: "TestValueWithEmoji🤯")
@@ -64,6 +64,9 @@ class HTTPTests: HTTPClientTestFixture {
         let streamBase = try connection.makeRequest(requestOptions: httpRequestOptions)
         try streamBase.activate()
         XCTAssertFalse(onCompleteCalled)
+        let metrics = connectionManager.fetchMetrics()
+        XCTAssertTrue(metrics.leasedConcurrency > 0)
+
         let data = TEST_DOC_LINE.data(using: .utf8)!
         for chunk in data.chunked(into: 5) {
             try await streamBase.writeChunk(chunk: chunk, endOfStream: false)
@@ -118,7 +121,7 @@ class HTTPTests: HTTPClientTestFixture {
         // Sleep for 5 seconds to make sure onComplete is not triggerred
         try await Task.sleep(nanoseconds: 5_000_000_000)
         XCTAssertFalse(onCompleteCalled)
-        
+
         let lastChunkData = Data("last chunk data".utf8)
         try await streamBase.writeChunk(chunk: lastChunkData, endOfStream: true)
         semaphore.wait()
@@ -135,7 +138,7 @@ class HTTPTests: HTTPClientTestFixture {
         XCTAssertEqual(body.data, TEST_DOC_LINE + String(decoding: lastChunkData, as: UTF8.self))
     }
 
-    
+
     func testHTTPStreamIsReleasedIfNotActivated() async throws {
         do {
             let httpRequestOptions = try getHTTPRequestOptions(method: "GET", endpoint: host, path: getPath)