gh-81536: Avoids repeated GIL acquisition when reading/writing to SSL sockets

Include/cpython/pyerrors.h

@@ -134,6 +134,7 @@ PyAPI_FUNC(PyObject *) _PyErr_TrySetFromCause(
 
 int PySignal_SetWakeupFd(int fd);
 PyAPI_FUNC(int) _PyErr_CheckSignals(void);
+PyAPI_FUNC(int) _PyErr_CheckSignalsTrippedNoGil(void);
 
 /* Support for adding program text to SyntaxErrors */
 

Lib/test/test_ssl.py

@@ -2120,6 +2120,49 @@ def test_bio_read_write_data(self):
         self.assertEqual(buf, b'foo\n')
         self.ssl_io_loop(sock, incoming, outgoing, sslobj.unwrap)
 
+    def test_bulk_nonblocking_read(self):
+        # 65536 bytes divide up into 4 TLS records (16 KB each)
+        # In nonblocking mode, we should be able to read all four in a single
+        # drop of the GIL.
+        size = 65536
+        trips = []
+
+        client_context, server_context, hostname = testing_context()
+        server = ThreadedEchoServer(context=server_context, chatty=False,
+                                    buffer_size=size)
+        with server:
+            sock = socket.create_connection((HOST, server.port))
+            sock.settimeout(0.0)
+            s = client_context.wrap_socket(sock, server_hostname=hostname,
+                                           do_handshake_on_connect=False)
+
+            with s:
+                while True:
+                    try:
+                        s.do_handshake()
+                        break
+                    except ssl.SSLWantReadError:
+                        select.select([s], [], [])
+                    except ssl.SSLWantWriteError:
+                        select.select([], [s], [])
+
+                s.send(b'\x00' * size)
+
+                select.select([s], [], [])
+
+                while size > 0:
+                    try:
+                        count = len(s.recv(size))
+                    except ssl.SSLWantReadError:
+                        select.select([s], [], [])
+                        # Give the sender some more time to complete sending.
+                        time.sleep(0.01)
+                    else:
+                        if count > 16384:
+                            return
+                        size -= count
+
+            self.fail("All TLS reads were smaller than 16KB")
 
 @support.requires_resource('network')
 class NetworkedTests(unittest.TestCase):
@@ -2179,7 +2222,7 @@ class ConnectionHandler(threading.Thread):
         with and without the SSL wrapper around the socket connection, so
         that we can test the STARTTLS functionality."""
 
-        def __init__(self, server, connsock, addr):
+        def __init__(self, server, connsock, addr, buffer_size):
             self.server = server
             self.running = False
             self.sock = connsock
@@ -2188,6 +2231,7 @@ def __init__(self, server, connsock, addr):
             self.sslconn = None
             threading.Thread.__init__(self)
             self.daemon = True
+            self.buffer_size = buffer_size
 
         def wrap_conn(self):
             try:
@@ -2253,9 +2297,9 @@ def wrap_conn(self):
 
         def read(self):
             if self.sslconn:
-                return self.sslconn.read()
+                return self.sslconn.read(self.buffer_size)
             else:
-                return self.sock.recv(1024)
+                return self.sock.recv(self.buffer_size)
 
         def write(self, bytes):
             if self.sslconn:
@@ -2374,7 +2418,8 @@ def __init__(self, certificate=None, ssl_version=None,
                  certreqs=None, cacerts=None,
                  chatty=True, connectionchatty=False, starttls_server=False,
                  alpn_protocols=None,
-                 ciphers=None, context=None):
+                 ciphers=None, context=None,
+                 buffer_size=1024):
         if context:
             self.context = context
         else:
@@ -2403,6 +2448,7 @@ def __init__(self, certificate=None, ssl_version=None,
         self.conn_errors = []
         threading.Thread.__init__(self)
         self.daemon = True
+        self.buffer_size = buffer_size
 
     def __enter__(self):
         self.start(threading.Event())
@@ -2430,7 +2476,8 @@ def run(self):
                 if support.verbose and self.chatty:
                     sys.stdout.write(' server:  new connection from '
                                      + repr(connaddr) + '\n')
-                handler = self.ConnectionHandler(self, newconn, connaddr)
+                handler = self.ConnectionHandler(self, newconn, connaddr,
+                                                 self.buffer_size)
                 handler.start()
                 handler.join()
             except TimeoutError as e: