Add maxConnections config to HttpClientConfiguration, and have it passed to HTTP client inits. (#915)

Co-authored-by: Sichan Yoo <[email protected]>

Author: sichanyoo

Sources/ClientRuntime/Config/DefaultSDKRuntimeConfiguration.swift

@@ -97,6 +97,7 @@ public extension DefaultSDKRuntimeConfiguration {
         let connectTimeoutMs = httpClientConfiguration.connectTimeout.map { UInt32($0 * 1000) }
         let socketTimeout = UInt32(httpClientConfiguration.socketTimeout)
         let config = CRTClientEngineConfig(
+            maxConnectionsPerEndpoint: httpClientConfiguration.maxConnections,
             telemetry: httpClientConfiguration.telemetry ?? CRTClientEngine.noOpCrtClientEngineTelemetry,
             connectTimeoutMs: connectTimeoutMs,
             crtTlsOptions: httpClientConfiguration.tlsConfiguration as? CRTClientTLSOptions,

Sources/ClientRuntime/Networking/Http/HttpClientConfiguration.swift

@@ -29,6 +29,12 @@ public class HttpClientConfiguration {
     /// If none is provided, defaults to no extra headers.
     public var defaultHeaders: Headers
 
+    /// The maximum connections the HTTP client makes per host or per endpoint depending on the OS.
+    ///
+    /// For Apple platforms, it will be per host.
+    /// For Linux, it will be per endpoint (protocol + host + port).
+    public var maxConnections: Int
+
     // add any other properties here you want to give the service operations
     // control over to be mapped to the Http Client
 
@@ -56,19 +62,30 @@ public class HttpClientConfiguration {
     ///   Note that certain headers may cause your API request to fail.  Defaults to no headers.
     ///   - protocolType: The HTTP scheme (`http` or `https`) to be used for API requests.  Defaults to the operation's standard configuration.
     ///   - tlsConfiguration: Optional custom TLS configuration for HTTPS requests. If `nil`, defaults to a standard configuration.
+    ///   - maxConnections: The maximum number of connections the HTTP client makes per host (for Apple platforms) or per endpoint (for Linux). For non-mac Apple platforms, defaults to 6. For macOS and Linux, defaults to 50.
     public init(
         connectTimeout: TimeInterval? = nil,
         socketTimeout: TimeInterval = 60.0,
         protocolType: URIScheme = .https,
         defaultHeaders: Headers = Headers(),
         tlsConfiguration: (any TLSConfiguration)? = nil,
-        telemetry: HttpTelemetry? = nil
+        telemetry: HttpTelemetry? = nil,
+        maxConnections: Int? = nil
     ) {
         self.socketTimeout = socketTimeout
         self.protocolType = protocolType
         self.defaultHeaders = defaultHeaders
         self.connectTimeout = connectTimeout
         self.tlsConfiguration = tlsConfiguration
         self.telemetry = telemetry
+        if let maxConnections {
+            self.maxConnections = maxConnections
+        } else {
+            #if os(macOS) || os(Linux)
+            self.maxConnections = 50
+            #else // iOS, ipadOS, watchOS, tvOS.
+            self.maxConnections = 6 // URLSession default.
+            #endif
+        }
     }
 }

Sources/ClientRuntime/Networking/Http/URLSession/URLSessionConfiguration+HTTPClientConfiguration.swift

@@ -17,6 +17,7 @@ extension URLSessionConfiguration {
         config.httpShouldSetCookies = false
         config.httpCookieAcceptPolicy = .never
         config.httpCookieStorage = nil
+        config.httpMaximumConnectionsPerHost = httpClientConfiguration.maxConnections
         return config
     }
 }