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Simplify client and server init (#1735)
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Motivation:

When configuring a client and server must users will specify only the
transport and services (for a server) and potentially interceptors too.
This should be the "easy" path. Moreover these are all reference types
so it makes sense to separate them from "raw" configuration.

Creating a client also diverged somewhat from the server. Having both
follow a similar pattern simplifies things for users.

Modifications:

- Move interceptors from the client config to the init.
- Modify the server to follow a similar pattern to the server.

Results:

Server and client are configured similarly.
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@glbrntt
glbrntt authored Dec 8, 2023
1 parent 39c567a commit 7986535
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Showing 6 changed files with 186 additions and 389 deletions.
6 changes: 0 additions & 6 deletions Sources/GRPCCore/ClientError.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,6 @@ extension ClientError {
public struct Code: Hashable, Sendable {
private enum Value {
case clientIsAlreadyRunning
case clientIsNotRunning
case clientIsStopped
case transportError
}
Expand All @@ -124,11 +123,6 @@ extension ClientError {
Self(.clientIsAlreadyRunning)
}

/// An attempt to start an RPC was made but the client is not running.
public static var clientIsNotRunning: Self {
Self(.clientIsNotRunning)
}

/// At attempt to start the client was made but it has already stopped.
public static var clientIsStopped: Self {
Self(.clientIsStopped)
Expand Down
101 changes: 34 additions & 67 deletions Sources/GRPCCore/GRPCClient.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -40,9 +40,6 @@ import Atomics
/// // Create a configuration object for the client.
/// var configuration = GRPCClient.Configuration()
///
/// // Create and add an interceptor.
/// configuration.interceptors.add(StatsRecordingClientInterceptor())
///
/// // Override the timeout for the 'Get' method on the 'echo.Echo' service. This configuration
/// // takes precedence over any set by the transport.
/// let echoGet = MethodDescriptor(service: "echo.Echo", method: "Get")
Expand All @@ -56,10 +53,15 @@ import Atomics
/// let defaultMethodConfiguration = MethodConfiguration(executionPolicy: nil, timeout: seconds(10))
/// configuration.method.defaults.setDefaultConfiguration(defaultMethodConfiguration)
///
/// // Finally create a transport and instantiate the client.
/// // Finally create a transport and instantiate the client, adding an interceptor.
/// let inProcessServerTransport = InProcessServerTransport()
/// let inProcessClientTransport = InProcessClientTransport(serverTransport: inProcessServerTransport)
/// let client = GRPCClient(transport: inProcessClientTransport, configuration: configuration)
///
/// let client = GRPCClient(
/// transport: inProcessClientTransport,
/// interceptors: [StatsRecordingClientInterceptor()],
/// configuration: configuration
/// )
/// ```
///
/// ## Starting and stopping the client
Expand Down Expand Up @@ -101,6 +103,14 @@ public struct GRPCClient: Sendable {
/// The transport which provides a bidirectional communication channel with the server.
private let transport: any ClientTransport

/// A collection of interceptors providing cross-cutting functionality to each accepted RPC.
///
/// The order in which interceptors are added reflects the order in which they are called. The
/// first interceptor added will be the first interceptor to intercept each request. The last
/// interceptor added will be the final interceptor to intercept each request before calling
/// the appropriate handler.
private let interceptors: [any ClientInterceptor]

/// The configuration used by the client.
public let configuration: Configuration

Expand All @@ -121,13 +131,23 @@ public struct GRPCClient: Sendable {
case stopped
}

/// Creates a new client with the given transport and configuration.
/// Creates a new client with the given transport, interceptors and configuration.
///
/// - Parameters:
/// - transport: The transport used to establish a communication channel with a server.
/// - interceptors: A collection of interceptors providing cross-cutting functionality to each
/// accepted RPC. The order in which interceptors are added reflects the order in which they
/// are called. The first interceptor added will be the first interceptor to intercept each
/// request. The last interceptor added will be the final interceptor to intercept each
/// request before calling the appropriate handler.
/// - configuration: Configuration for the client.
public init(transport: some ClientTransport, configuration: Configuration = Configuration()) {
public init(
transport: some ClientTransport,
interceptors: [any ClientInterceptor] = [],
configuration: Configuration = Configuration()
) {
self.transport = transport
self.interceptors = interceptors
self.configuration = configuration
self.state = ManagedAtomic(.notStarted)
}
Expand Down Expand Up @@ -250,7 +270,7 @@ public struct GRPCClient: Sendable {
deserializer: some MessageDeserializer<Response>,
handler: @Sendable @escaping (ClientResponse.Single<Response>) async throws -> ReturnValue
) async throws -> ReturnValue {
try await bidirectionalStreaming(
try await self.bidirectionalStreaming(
request: ClientRequest.Stream(single: request),
descriptor: descriptor,
serializer: serializer,
Expand Down Expand Up @@ -278,7 +298,7 @@ public struct GRPCClient: Sendable {
deserializer: some MessageDeserializer<Response>,
handler: @Sendable @escaping (ClientResponse.Single<Response>) async throws -> ReturnValue
) async throws -> ReturnValue {
try await bidirectionalStreaming(
try await self.bidirectionalStreaming(
request: request,
descriptor: descriptor,
serializer: serializer,
Expand Down Expand Up @@ -306,7 +326,7 @@ public struct GRPCClient: Sendable {
deserializer: some MessageDeserializer<Response>,
handler: @Sendable @escaping (ClientResponse.Stream<Response>) async throws -> ReturnValue
) async throws -> ReturnValue {
try await bidirectionalStreaming(
try await self.bidirectionalStreaming(
request: ClientRequest.Stream(single: request),
descriptor: descriptor,
serializer: serializer,
Expand Down Expand Up @@ -336,13 +356,10 @@ public struct GRPCClient: Sendable {
handler: @Sendable @escaping (ClientResponse.Stream<Response>) async throws -> ReturnValue
) async throws -> ReturnValue {
switch self.state.load(ordering: .sequentiallyConsistent) {
case .running:
case .notStarted, .running:
// Allow .notStarted as making a request can race with 'run()'. Transports should tolerate
// queuing the request if not yet started.
()
case .notStarted:
throw ClientError(
code: .clientIsNotRunning,
message: "Client must be running to make an RPC: call run() first."
)
case .stopping, .stopped:
throw ClientError(
code: .clientIsStopped,
Expand All @@ -357,7 +374,7 @@ public struct GRPCClient: Sendable {
serializer: serializer,
deserializer: deserializer,
transport: self.transport,
interceptors: self.configuration.interceptors.values,
interceptors: self.interceptors,
handler: handler
)
}
Expand All @@ -383,14 +400,6 @@ public struct GRPCClient: Sendable {
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
extension GRPCClient {
public struct Configuration: Sendable {
/// A collection of interceptors providing cross-cutting functionality to each accepted RPC.
///
/// The order in which interceptors are added reflects the order in which they are called. The
/// first interceptor added will be the first interceptor to intercept each request. The last
/// interceptor added will be the final interceptor to intercept each request before calling
/// the appropriate handler.
public var interceptors: Interceptors

/// Configuration for how methods are executed.
///
/// Method configuration determines how each RPC is executed by the client. Some services and
Expand All @@ -401,48 +410,13 @@ extension GRPCClient {

/// Creates a new default configuration.
public init() {
self.interceptors = Interceptors()
self.method = Method()
}
}
}

@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
extension GRPCClient.Configuration {
/// A collection of ``ClientInterceptor`` implementations which are applied to all accepted
/// RPCs.
///
/// RPCs are intercepted in the order that interceptors are added. That is, a request sent from the client to
/// the server will first be intercepted by the first added interceptor followed by the second, and so on.
/// For responses from the server, they'll be applied in the opposite order.
public struct Interceptors: Sendable {
private(set) var values: [any ClientInterceptor] = []

/// Add an interceptor to the client.
///
/// The order in which interceptors are added reflects the order in which they are called. The
/// first interceptor added will be the first interceptor to intercept each request. The last
/// interceptor added will be the final interceptor to intercept each request before calling
/// the appropriate handler.
///
/// - Parameter interceptor: The interceptor to add.
public mutating func add(_ interceptor: some ClientInterceptor) {
self.values.append(interceptor)
}

/// Adds a sequence of interceptor to the client.
///
/// The order in which interceptors are added reflects the order in which they are called. The
/// first interceptor added will be the first interceptor to intercept each request. The last
/// interceptor added will be the final interceptor to intercept each request before calling
/// the appropriate handler.
///
/// - Parameter interceptors: The interceptors to add.
public mutating func add(contentsOf interceptors: some Sequence<ClientInterceptor>) {
self.values.append(contentsOf: interceptors)
}
}

/// Configuration for how methods should be executed.
///
/// In most cases the client should defer to the configuration provided by the transport as this
Expand All @@ -464,10 +438,3 @@ extension GRPCClient.Configuration {
}
}
}

@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
extension GRPCClient.Configuration.Interceptors: CustomStringConvertible {
public var description: String {
return String(describing: self.values.map { String(describing: type(of: $0)) })
}
}
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