fix promise leak (vapor#57)

* fix promise leak

* remove comment

* fix channel write promise

Author: tanner0101

Sources/PostgresNIO/Connection/PostgresRequest.swift

@@ -83,16 +83,6 @@ final class PostgresRequestHandler: ChannelDuplexHandler {
         }
     }
 
-    private func _write(context: ChannelHandlerContext, data: NIOAny, promise: EventLoopPromise<Void>?) throws {
-        let request = self.unwrapOutboundIn(data)
-        self.queue.append(request)
-        let messages = try request.delegate.start()
-        for message in messages {
-            context.write(self.wrapOutboundOut(message), promise: nil)
-        }
-        context.flush()
-    }
-    
     func channelRead(context: ChannelHandlerContext, data: NIOAny) {
         do {
             try self._channelRead(context: context, data: data)
@@ -102,9 +92,14 @@ final class PostgresRequestHandler: ChannelDuplexHandler {
     }
 
     func write(context: ChannelHandlerContext, data: NIOAny, promise: EventLoopPromise<Void>?) {
+        let request = self.unwrapOutboundIn(data)
+        self.queue.append(request)
         do {
-            try self._write(context: context, data: data, promise: promise)
+            let messages = try request.delegate.start()
+            self.write(context: context, items: messages, promise: promise)
+            context.flush()
         } catch {
+            promise?.fail(error)
             self.errorCaught(context: context, error: error)
         }
     }
@@ -117,3 +112,18 @@ final class PostgresRequestHandler: ChannelDuplexHandler {
         context.close(mode: mode, promise: promise)
     }
 }
+
+
+extension ChannelInboundHandler {
+    func write(context: ChannelHandlerContext, items: [OutboundOut], promise: EventLoopPromise<Void>?) {
+        var items = items
+        if let last = items.popLast() {
+            for item in items {
+                context.write(self.wrapOutboundOut(item), promise: nil)
+            }
+            context.write(self.wrapOutboundOut(last), promise: promise)
+        } else {
+            promise?.succeed(())
+        }
+    }
+}

Sources/PostgresNIO/Data/PostgresData+Double.swift

@@ -31,3 +31,20 @@ extension PostgresData {
         }
     }
 }
+
+extension Double: PostgresDataConvertible {
+    public static var postgresDataType: PostgresDataType {
+        return .float8
+    }
+
+    public init?(postgresData: PostgresData) {
+        guard let double = postgresData.double else {
+            return nil
+        }
+        self = double
+    }
+
+    public var postgresData: PostgresData? {
+        return .init(double: self)
+    }
+}

Sources/PostgresNIO/Data/PostgresData+Float.swift

@@ -27,3 +27,20 @@ extension PostgresData {
         }
     }
 }
+
+extension Float: PostgresDataConvertible {
+    public static var postgresDataType: PostgresDataType {
+        return .float4
+    }
+
+    public init?(postgresData: PostgresData) {
+        guard let float = postgresData.float else {
+            return nil
+        }
+        self = float
+    }
+
+    public var postgresData: PostgresData? {
+        return .init(float: self)
+    }
+}