Add async implementation of EventLoopGroup.shutdownGracefully to _NIO…

…Concurrency (#1879) * Add async implementation of EventLoopGroup.shutdownGracefully to _NIOConcurrency Signed-off-by: Si Beaumont <[email protected]> * fixup: Move elg lifecycle into async function in async demo * fixup: Ensure continuation is run exactly once * fixup: Shutdown event loop group in catch in async demo
apple · Jun 14, 2021 · 7f3a2f5 · 7f3a2f5
1 parent a1f4052
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Showing 2 changed files with 30 additions and 7 deletions.
diff --git a/Sources/NIOAsyncAwaitDemo/main.swift b/Sources/NIOAsyncAwaitDemo/main.swift
@@ -22,13 +22,8 @@ import Dispatch
 
 import _Concurrency
 
-let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
-defer {
-    try! group.syncShutdownGracefully()
-}
-
 @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
-func makeHTTPChannel(host: String, port: Int) async throws -> AsyncChannelIO<HTTPRequestHead, NIOHTTPClientResponseFull> {
+func makeHTTPChannel(host: String, port: Int, group: EventLoopGroup) async throws -> AsyncChannelIO<HTTPRequestHead, NIOHTTPClientResponseFull> {
     let channel = try await ClientBootstrap(group: group).connect(host: host, port: port).get()
     try await channel.pipeline.addHTTPClientHandlers().get()
     try await channel.pipeline.addHandler(NIOHTTPClientResponseAggregator(maxContentLength: 1_000_000))
@@ -38,8 +33,9 @@ func makeHTTPChannel(host: String, port: Int) async throws -> AsyncChannelIO<HTT
 
 @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
 func main() async {
+    let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
     do {
-        let channel = try await makeHTTPChannel(host: "httpbin.org", port: 80)
+        let channel = try await makeHTTPChannel(host: "httpbin.org", port: 80, group: group)
         print("OK, connected to \(channel)")
 
         print("Sending request 1", terminator: "")
@@ -57,9 +53,19 @@ func main() async {
         print(", response:", String(buffer: response2.body ?? ByteBuffer()))
 
         try await channel.close()
+
+        print("Shutting down event loop group...")
+        try await group.shutdownGracefully()
+
         print("all, done")
     } catch {
         print("ERROR: \(error)")
+        print("Shutting down event loop group (possibly for a second time)...")
+        do {
+            try await group.shutdownGracefully()
+        } catch {
+            print("Error shutting down event loop group: \(error)")
+        }
     }
 }
 

diff --git a/Sources/_NIOConcurrency/AsyncAwaitSupport.swift b/Sources/_NIOConcurrency/AsyncAwaitSupport.swift
@@ -38,6 +38,23 @@ extension EventLoopFuture {
     }
 }
 
+extension EventLoopGroup {
+    /// Shuts down the event loop gracefully.
+    @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+    @inlinable
+    public func shutdownGracefully() async throws {
+        return try await withCheckedThrowingContinuation { cont in
+            self.shutdownGracefully { error in
+                if let error = error {
+                    cont.resume(throwing: error)
+                } else {
+                    cont.resume()
+                }
+            }
+        }
+    }
+}
+
 extension EventLoopPromise {
     /// Complete a future with the result (or error) of the `async` function `body`.
     ///