Use an empty string instead on None in the copy work queue

The test for copy end is just "if not item", so the empty string is
actually never used as a piece of data. This simplifies the type of the
queue.

diff --git a/psycopg/psycopg/copy.py b/psycopg/psycopg/copy.py
index 572b9699d61850d52db9937ac2ad415892a888e7..189f70d75c31ef434191c4e241b59347ff5e2d93 100644 (file)
--- a/psycopg/psycopg/copy.py
+++ b/psycopg/psycopg/copy.py
@@ -168,9 +168,7 @@ class Copy(BaseCopy["Connection[Any]"]):
 
     def __init__(self, cursor: "Cursor[Any]"):
         super().__init__(cursor)
-        self._queue: queue.Queue[Optional[bytes]] = queue.Queue(
-            maxsize=self.QUEUE_SIZE
-        )
+        self._queue: queue.Queue[bytes] = queue.Queue(maxsize=self.QUEUE_SIZE)
         self._worker: Optional[threading.Thread] = None
 
     def __enter__(self) -> "Copy":
@@ -286,7 +284,7 @@ class Copy(BaseCopy["Connection[Any]"]):
     def _write_end(self) -> None:
         data = self.formatter.end()
         self._write(data)
-        self._queue.put(None)
+        self._queue.put(b"")
 
         if self._worker:
             self._worker.join()
@@ -300,7 +298,7 @@ class AsyncCopy(BaseCopy["AsyncConnection[Any]"]):
 
     def __init__(self, cursor: "AsyncCursor[Any]"):
         super().__init__(cursor)
-        self._queue: asyncio.Queue[Optional[bytes]] = asyncio.Queue(
+        self._queue: asyncio.Queue[bytes] = asyncio.Queue(
             maxsize=self.QUEUE_SIZE
         )
         self._worker: Optional[asyncio.Future[None]] = None
@@ -380,7 +378,7 @@ class AsyncCopy(BaseCopy["AsyncConnection[Any]"]):
     async def _write_end(self) -> None:
         data = self.formatter.end()
         await self._write(data)
-        await self._queue.put(None)
+        await self._queue.put(b"")
 
         if self._worker:
             await asyncio.gather(self._worker)