small close fixes and asymetric stream fix

Author: tanner0101

Sources/PostgreSQL/Connection/PostgreSQLConnection.swift

@@ -144,14 +144,14 @@ public final class AsymmetricQueueStream<I, O>: Stream, ConnectionContext {
 
             do {
                 if try context.onInput(input) {
-                    context.promise.complete()
                     currentInput = nil
+                    context.promise.complete()
                 } else {
                     upstream!.request(count: 1)
                 }
             } catch {
-                context.promise.fail(error)
                 currentInput = nil
+                context.promise.fail(error)
             }
         }
     }

Sources/PostgreSQL/Message/PostgreSQLClose.swift

@@ -0,0 +1,35 @@
+import Bits
+
+/// Identifies the message as a Close command.
+struct PostgreSQLClose: Decodable {
+    /// 'S' to close a prepared statement; or 'P' to close a portal.
+    var type: PostgreSQLCloseType
+
+    /// See `Decodable.init(from:)`
+    init(from decoder: Decoder) throws {
+        let single = try decoder.singleValueContainer()
+        let string = try single.decode(String.self)
+        /// This message format is overloaded with `C` byte identifier.
+        /// We need to do some checking to see what type it actually is.
+        switch string.first {
+        case .some(let c):
+            switch c {
+            case "S": type = .statement(name: String(string[string.index(after: string.startIndex)...]))
+            case "P": type = .portal(name: String(string[string.index(after: string.startIndex)...]))
+            default: type = .command(string)
+            }
+        default: type = .command(string)
+        }
+    }
+}
+
+
+enum PostgreSQLCloseType {
+    /// The name of the prepared statement or portal to close (an empty string selects the unnamed prepared statement or portal).
+    case statement(name: String)
+    /// The name of the prepared statement or portal to close (an empty string selects the unnamed prepared statement or portal).
+    case portal(name: String)
+    /// The command tag. This is usually a single word that identifies which SQL command was completed.
+    case command(String)
+}
+

Sources/PostgreSQL/Message/PostgreSQLCloseCommand.swift

@@ -14,7 +14,8 @@ enum PostgreSQLMessage {
     case query(PostgreSQLQuery)
     case rowDescription(PostgreSQLRowDescription)
     case dataRow(PostgreSQLDataRow)
-    case close(PostgreSQLCloseCommand)
+    /// Identifies the message as a command-completed response.
+    case close(PostgreSQLClose)
     case parse(PostgreSQLParseRequest)
     /// Identifies the message as a parameter description.
     case parameterDescription(PostgreSQLParameterDescription)