BaseStreamSocketChannel half-close allows outstanding writes to complete

Sources/NIOPosix/BaseStreamSocketChannel.swift

@@ -194,11 +194,19 @@ class BaseStreamSocketChannel<Socket: SocketProtocol>: BaseSocketChannel<Socket>
                     self.close0(error: error, mode: .all, promise: promise)
                     return
                 }
-                try self.shutdownSocket(mode: mode)
-                // Fail all pending writes and so ensure all pending promises are notified
-                self.pendingWrites.failAll(error: error, close: false)
                 self.unregisterForWritable()
-                promise?.succeed(())
+
+                // Shutdown the socket only when the pending writes are dealt with
+                let closePromise = self.eventLoop.makePromise(of: Void.self)
+                closePromise.futureResult.whenComplete { _ in
+                    do {
+                        try self.shutdownSocket(mode: mode)
+                        promise?.succeed(())
+                    } catch let err {
+                        promise?.fail(err)
+                    }
+                }
+                self.pendingWrites.close(closePromise)
 
                 self.pipeline.fireUserInboundEventTriggered(ChannelEvent.outputClosed)
             case .input:

Sources/NIOPosix/PendingDatagramWritesManager.swift

@@ -268,7 +268,8 @@ private struct PendingDatagramWritesState {
         // When we've hit an error we treat it like fully writing the first datagram. We aren't going to try to
         // send it again.
         let promiseFiller = self.wroteFirst(error: error)
-        let result: OneWriteOperationResult = self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely
+        let result: OneWriteOperationResult =
+            self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely(closePromise: nil)
 
         return (promiseFiller, result)
     }
@@ -305,7 +306,8 @@ private struct PendingDatagramWritesState {
         }
 
         // If we no longer have a mark, we wrote everything.
-        let result: OneWriteOperationResult = self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely
+        let result: OneWriteOperationResult =
+            self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely(closePromise: nil)
         return (promiseFiller, result)
     }
 
@@ -322,7 +324,8 @@ private struct PendingDatagramWritesState {
         )
         let writeFiller = self.wroteFirst()
         // If we no longer have a mark, we wrote everything.
-        let result: OneWriteOperationResult = self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely
+        let result: OneWriteOperationResult =
+            self.pendingWrites.hasMark ? .writtenPartially : .writtenCompletely(closePromise: nil)
         return (writeFiller, result)
     }
 
@@ -565,7 +568,7 @@ final class PendingDatagramWritesManager: PendingWritesManager {
                 preconditionFailure("PendingDatagramWritesManager was handed a file write")
             case .nothingToBeWritten:
                 assertionFailure("called \(#function) with nothing available to be written")
-                return OneWriteOperationResult.writtenCompletely
+                return OneWriteOperationResult.writtenCompletely(closePromise: nil)
             }
         }
     }