feat: add more detailed error messages to TCP client

Author: buraksezer

internal/transport/client.go

@@ -136,11 +136,12 @@ func (c *Client) conn(addr string) (net.Conn, error) {
 		// Wrap the net.Conn to implement timeout logic
 		conn = NewConnWithTimeout(conn, c.config.ReadTimeout, c.config.WriteTimeout)
 	}
-	return conn, err
+	return conn, nil
 }
 
 func (c *Client) teardownConnWithTimeout(conn *ConnWithTimeout, dead bool) {
 	if dead {
+		CurrentConnections.Decrease(1)
 		conn.MarkUnusable()
 	} else {
 		if err := conn.UnsetDeadline(); err != nil {
@@ -194,7 +195,7 @@ func (c *Client) RequestTo(addr string, req protocol.EncodeDecoder) (protocol.En
 	nr, err := req.Buffer().WriteTo(conn)
 	if err != nil {
 		dead = true
-		return nil, err
+		return nil, fmt.Errorf("failed to write message: %w", err)
 	}
 	WrittenBytesTotal.Increase(nr)
 
@@ -204,7 +205,7 @@ func (c *Client) RequestTo(addr string, req protocol.EncodeDecoder) (protocol.En
 	if err != nil {
 		// Failed to read message from the TCP socket. Close it.
 		dead = true
-		return nil, err
+		return nil, fmt.Errorf("failed to read message: %w", err)
 	}
 
 	ReadBytesTotal.Increase(protocol.HeaderLength + int64(h.MessageLength))

internal/transport/timeout_test.go

@@ -17,6 +17,7 @@ package transport
 import (
 	"bytes"
 	"context"
+	"errors"
 	"net"
 	"sync/atomic"
 	"testing"
@@ -57,6 +58,7 @@ func TestConnWithTimeout(t *testing.T) {
 			defer cancel()
 			req := protocol.NewDMapMessage(protocol.OpPut)
 			_, err := c.RequestTo(s.listener.Addr().String(), req)
+			err = errors.Unwrap(err)
 			if err.(*net.OpError).Err.Error() != "i/o timeout" {
 				t.Errorf("Expected i/o timeout. Got: %v", err)
 			}