From 37294a2de465b100fe3e8c40eb4fc46316ed5bd5 Mon Sep 17 00:00:00 2001
From: Alexey Palazhchenko <alexey.palazhchenko@ferretdb.io>
Date: Wed, 17 Jul 2024 12:14:14 +0400
Subject: [PATCH] Simplify

---
 wireclient/wiredriver.go | 52 +++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 28 deletions(-)

diff --git a/wireclient/wiredriver.go b/wireclient/wiredriver.go
index 051c74d..d346fd9 100644
--- a/wireclient/wiredriver.go
+++ b/wireclient/wiredriver.go
@@ -28,8 +28,8 @@ import (
 	"github.com/FerretDB/wire/internal/util/lazyerrors"
 )
 
-// lastRequestID stores last generated request ID.
-var lastRequestID atomic.Int32
+// nextRequestID stores the last generated request ID.
+var nextRequestID atomic.Int32
 
 // Conn represents a single client connection.
 //
@@ -38,12 +38,12 @@ type Conn struct {
 	c net.Conn
 	r *bufio.Reader
 	w *bufio.Writer
-	l *slog.Logger // debug level only
+	l *slog.Logger // debug-level only
 }
 
 // New wraps the given connection.
 //
-// The passed logger will be used only for debug level messages.
+// The passed logger will be used only for debug-level messages.
 func New(c net.Conn, l *slog.Logger) *Conn {
 	return &Conn{
 		c: c,
@@ -57,6 +57,8 @@ func New(c net.Conn, l *slog.Logger) *Conn {
 //
 // Context can be used to cancel the connection attempt.
 // Canceling the context after the connection is established has no effect.
+//
+// The passed logger will be used only for debug-level messages.
 func Connect(ctx context.Context, uri string, l *slog.Logger) (*Conn, error) {
 	u, err := url.Parse(uri)
 	if err != nil {
@@ -181,41 +183,41 @@ func (c *Conn) WriteRaw(ctx context.Context, b []byte) error {
 }
 
 // Request sends the given request to the connection and returns the response.
-// If header MessageLength or RequestID is not specified, it assigns the proper values.
-// For header.OpCode the wire.OpCodeMsg is used as default.
+// If header's MessageLength or RequestID are not specified, it assigns the proper values.
+// For header's OpCode the [wire.OpCodeMsg] is used as default.
+//
+// Passed context's deadline is honored if set.
 //
-// It returns errors only for request/response parsing issues, or connection issues.
-// All of the driver level errors are stored inside response.
+// It returns errors only for request/response parsing or connection issues.
+// All protocol-level errors are stored inside response.
 func (c *Conn) Request(ctx context.Context, header *wire.MsgHeader, body wire.MsgBody) (*wire.MsgHeader, wire.MsgBody, error) {
 	if header == nil {
 		header = new(wire.MsgHeader)
 	}
 
 	if header.MessageLength == 0 {
-		msgBin, err := body.MarshalBinary()
+		b, err := body.MarshalBinary()
 		if err != nil {
 			return nil, nil, lazyerrors.Error(err)
 		}
 
-		header.MessageLength = int32(len(msgBin) + wire.MsgHeaderLen)
-	}
-
-	if header.OpCode == 0 {
-		header.OpCode = wire.OpCodeMsg
+		header.MessageLength = int32(len(b) + wire.MsgHeaderLen)
 	}
 
 	if header.RequestID == 0 {
-		header.RequestID = lastRequestID.Add(1)
+		header.RequestID = nextRequestID.Add(1)
 	}
 
 	if header.ResponseTo != 0 {
 		return nil, nil, lazyerrors.Errorf("setting response_to is not allowed")
 	}
 
-	if m, ok := body.(*wire.OpMsg); ok {
-		if m.Flags != 0 {
-			return nil, nil, lazyerrors.Errorf("unsupported request flags %s", m.Flags)
-		}
+	if header.OpCode == 0 {
+		header.OpCode = wire.OpCodeMsg
+	}
+
+	if body == nil {
+		return nil, nil, lazyerrors.Errorf("body can't be nil")
 	}
 
 	if err := c.Write(ctx, header, body); err != nil {
@@ -228,18 +230,12 @@ func (c *Conn) Request(ctx context.Context, header *wire.MsgHeader, body wire.Ms
 	}
 
 	if resHeader.ResponseTo != header.RequestID {
-		return nil, nil, lazyerrors.Errorf(
-			"response_to is not equal to request_id (response_to=%d; expected=%d)",
+		err = fmt.Errorf(
+			"response's response_to=%d is not equal to request's request_id=%d",
 			resHeader.ResponseTo,
 			header.RequestID,
 		)
 	}
 
-	if m, ok := resBody.(*wire.OpMsg); ok {
-		if m.Flags != 0 {
-			return nil, nil, lazyerrors.Errorf("unsupported response flags %s", m.Flags)
-		}
-	}
-
-	return resHeader, resBody, nil
+	return resHeader, resBody, err
 }