Add option to force sending text or binary frames.

This adds the same functionality to the threading implemetation
as bc4b8f2 did to the asyncio implementation. Refs #1515.

src/websockets/asyncio/connection.py

@@ -409,19 +409,17 @@ async def send(
         # strings and bytes-like objects are iterable.
 
         if isinstance(message, str):
-            if text is False:
-                async with self.send_context():
+            async with self.send_context():
+                if text is False:
                     self.protocol.send_binary(message.encode())
-            else:
-                async with self.send_context():
+                else:
                     self.protocol.send_text(message.encode())
 
         elif isinstance(message, BytesLike):
-            if text is True:
-                async with self.send_context():
+            async with self.send_context():
+                if text is True:
                     self.protocol.send_text(message)
-            else:
-                async with self.send_context():
+                else:
                     self.protocol.send_binary(message)
 
         # Catch a common mistake -- passing a dict to send().
@@ -443,19 +441,17 @@ async def send(
             try:
                 # First fragment.
                 if isinstance(chunk, str):
-                    if text is False:
-                        async with self.send_context():
+                    async with self.send_context():
+                        if text is False:
                             self.protocol.send_binary(chunk.encode(), fin=False)
-                    else:
-                        async with self.send_context():
+                        else:
                             self.protocol.send_text(chunk.encode(), fin=False)
                     encode = True
                 elif isinstance(chunk, BytesLike):
-                    if text is True:
-                        async with self.send_context():
+                    async with self.send_context():
+                        if text is True:
                             self.protocol.send_text(chunk, fin=False)
-                    else:
-                        async with self.send_context():
+                        else:
                             self.protocol.send_binary(chunk, fin=False)
                     encode = False
                 else:
@@ -480,7 +476,10 @@ async def send(
                 # We're half-way through a fragmented message and we can't
                 # complete it. This makes the connection unusable.
                 async with self.send_context():
-                    self.protocol.fail(1011, "error in fragmented message")
+                    self.protocol.fail(
+                        CloseCode.INTERNAL_ERROR,
+                        "error in fragmented message",
+                    )
                 raise
 
             finally:
@@ -538,7 +537,10 @@ async def send(
                 # We're half-way through a fragmented message and we can't
                 # complete it. This makes the connection unusable.
                 async with self.send_context():
-                    self.protocol.fail(1011, "error in fragmented message")
+                    self.protocol.fail(
+                        CloseCode.INTERNAL_ERROR,
+                        "error in fragmented message",
+                    )
                 raise
 
             finally:
@@ -568,7 +570,10 @@ async def close(self, code: int = 1000, reason: str = "") -> None:
             # to terminate after calling a method that sends a close frame.
             async with self.send_context():
                 if self.fragmented_send_waiter is not None:
-                    self.protocol.fail(1011, "close during fragmented message")
+                    self.protocol.fail(
+                        CloseCode.INTERNAL_ERROR,
+                        "close during fragmented message",
+                    )
                 else:
                     self.protocol.send_close(code, reason)
         except ConnectionClosed:

src/websockets/sync/connection.py

@@ -251,7 +251,11 @@ def recv_streaming(self) -> Iterator[Data]:
                 "is already running recv or recv_streaming"
             ) from None
 
-    def send(self, message: Data | Iterable[Data]) -> None:
+    def send(
+        self,
+        message: Data | Iterable[Data],
+        text: bool | None = None,
+    ) -> None:
         """
         Send a message.
 
@@ -262,6 +266,17 @@ def send(self, message: Data | Iterable[Data]) -> None:
         .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
         .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6
 
+        You may override this behavior with the ``text`` argument:
+
+        * Set ``text=True`` to send a bytestring or bytes-like object
+          (:class:`bytes`, :class:`bytearray`, or :class:`memoryview`) as a
+          Text_ frame. This improves performance when the message is already
+          UTF-8 encoded, for example if the message contains JSON and you're
+          using a JSON library that produces a bytestring.
+        * Set ``text=False`` to send a string (:class:`str`) in a Binary_
+          frame. This may be useful for servers that expect binary frames
+          instead of text frames.
+
         :meth:`send` also accepts an iterable of strings, bytestrings, or
         bytes-like objects to enable fragmentation_. Each item is treated as a
         message fragment and sent in its own frame. All items must be of the
@@ -300,7 +315,10 @@ def send(self, message: Data | Iterable[Data]) -> None:
                         "cannot call send while another thread "
                         "is already running send"
                     )
-                self.protocol.send_text(message.encode())
+                if text is False:
+                    self.protocol.send_binary(message.encode())
+                else:
+                    self.protocol.send_text(message.encode())
 
         elif isinstance(message, BytesLike):
             with self.send_context():
@@ -309,7 +327,10 @@ def send(self, message: Data | Iterable[Data]) -> None:
                         "cannot call send while another thread "
                         "is already running send"
                     )
-                self.protocol.send_binary(message)
+                if text is True:
+                    self.protocol.send_text(message)
+                else:
+                    self.protocol.send_binary(message)
 
         # Catch a common mistake -- passing a dict to send().
 
@@ -328,50 +349,44 @@ def send(self, message: Data | Iterable[Data]) -> None:
             try:
                 # First fragment.
                 if isinstance(chunk, str):
-                    text = True
                     with self.send_context():
                         if self.send_in_progress:
                             raise ConcurrencyError(
                                 "cannot call send while another thread "
                                 "is already running send"
                             )
                         self.send_in_progress = True
-                        self.protocol.send_text(
-                            chunk.encode(),
-                            fin=False,
-                        )
+                        if text is False:
+                            self.protocol.send_binary(chunk.encode(), fin=False)
+                        else:
+                            self.protocol.send_text(chunk.encode(), fin=False)
+                    encode = True
                 elif isinstance(chunk, BytesLike):
-                    text = False
                     with self.send_context():
                         if self.send_in_progress:
                             raise ConcurrencyError(
                                 "cannot call send while another thread "
                                 "is already running send"
                             )
                         self.send_in_progress = True
-                        self.protocol.send_binary(
-                            chunk,
-                            fin=False,
-                        )
+                        if text is True:
+                            self.protocol.send_text(chunk, fin=False)
+                        else:
+                            self.protocol.send_binary(chunk, fin=False)
+                    encode = False
                 else:
                     raise TypeError("data iterable must contain bytes or str")
 
                 # Other fragments
                 for chunk in chunks:
-                    if isinstance(chunk, str) and text:
+                    if isinstance(chunk, str) and encode:
                         with self.send_context():
                             assert self.send_in_progress
-                            self.protocol.send_continuation(
-                                chunk.encode(),
-                                fin=False,
-                            )
-                    elif isinstance(chunk, BytesLike) and not text:
+                            self.protocol.send_continuation(chunk.encode(), fin=False)
+                    elif isinstance(chunk, BytesLike) and not encode:
                         with self.send_context():
                             assert self.send_in_progress
-                            self.protocol.send_continuation(
-                                chunk,
-                                fin=False,
-                            )
+                            self.protocol.send_continuation(chunk, fin=False)
                     else:
                         raise TypeError("data iterable must contain uniform types")
 

tests/sync/test_connection.py

@@ -308,6 +308,16 @@ def test_send_binary(self):
         self.connection.send(b"\x01\x02\xfe\xff")
         self.assertEqual(self.remote_connection.recv(), b"\x01\x02\xfe\xff")
 
+    def test_send_binary_from_str(self):
+        """send sends a binary message from a str."""
+        self.connection.send("😀", text=False)
+        self.assertEqual(self.remote_connection.recv(), "😀".encode())
+
+    def test_send_text_from_bytes(self):
+        """send sends a text message from bytes."""
+        self.connection.send("😀".encode(), text=True)
+        self.assertEqual(self.remote_connection.recv(), "😀")
+
     def test_send_fragmented_text(self):
         """send sends a fragmented text message."""
         self.connection.send(["😀", "😀"])
@@ -326,6 +336,24 @@ def test_send_fragmented_binary(self):
             [b"\x01\x02", b"\xfe\xff", b""],
         )
 
+    def test_send_fragmented_binary_from_str(self):
+        """send sends a fragmented binary message from a str."""
+        self.connection.send(["😀", "😀"], text=False)
+        # websockets sends an trailing empty fragment. That's an implementation detail.
+        self.assertEqual(
+            list(self.remote_connection.recv_streaming()),
+            ["😀".encode(), "😀".encode(), b""],
+        )
+
+    def test_send_fragmented_text_from_bytes(self):
+        """send sends a fragmented text message from bytes."""
+        self.connection.send(["😀".encode(), "😀".encode()], text=True)
+        # websockets sends an trailing empty fragment. That's an implementation detail.
+        self.assertEqual(
+            list(self.remote_connection.recv_streaming()),
+            ["😀", "😀", ""],
+        )
+
     def test_send_connection_closed_ok(self):
         """send raises ConnectionClosedOK after a normal closure."""
         self.remote_connection.close()