gh-76785: Add SendChannel.send_buffer() (#110246)

(This is still a test module.)

Author: ericsnowcurrently

Include/internal/pycore_ceval.h

@@ -41,12 +41,26 @@ extern void _PyEval_InitState(PyInterpreterState *, PyThread_type_lock);
 extern void _PyEval_FiniState(struct _ceval_state *ceval);
 extern void _PyEval_SignalReceived(PyInterpreterState *interp);
 
+// bitwise flags:
+#define _Py_PENDING_MAINTHREADONLY 1
+#define _Py_PENDING_RAWFREE 2
+
 // Export for '_testinternalcapi' shared extension
 PyAPI_FUNC(int) _PyEval_AddPendingCall(
     PyInterpreterState *interp,
     _Py_pending_call_func func,
     void *arg,
-    int mainthreadonly);
+    int flags);
+
+typedef int (*_Py_simple_func)(void *);
+extern int _Py_CallInInterpreter(
+    PyInterpreterState *interp,
+    _Py_simple_func func,
+    void *arg);
+extern int _Py_CallInInterpreterAndRawFree(
+    PyInterpreterState *interp,
+    _Py_simple_func func,
+    void *arg);
 
 extern void _PyEval_SignalAsyncExc(PyInterpreterState *interp);
 #ifdef HAVE_FORK

Include/internal/pycore_ceval_state.h

@@ -22,6 +22,7 @@ struct _pending_calls {
     struct _pending_call {
         _Py_pending_call_func func;
         void *arg;
+        int flags;
     } calls[NPENDINGCALLS];
     int first;
     int last;

Include/internal/pycore_interp.h

@@ -267,7 +267,8 @@ _PyInterpreterState_SetFinalizing(PyInterpreterState *interp, PyThreadState *tst
 }
 
 
-extern PyInterpreterState* _PyInterpreterState_LookUpID(int64_t);
+// Export for the _xxinterpchannels module.
+PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpID(int64_t);
 
 extern int _PyInterpreterState_IDInitref(PyInterpreterState *);
 extern int _PyInterpreterState_IDIncref(PyInterpreterState *);

Include/internal/pycore_pybuffer.h

@@ -0,0 +1,21 @@
+#ifndef Py_INTERNAL_PYBUFFER_H
+#define Py_INTERNAL_PYBUFFER_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+
+// Exported for the _xxinterpchannels module.
+PyAPI_FUNC(int) _PyBuffer_ReleaseInInterpreter(
+        PyInterpreterState *interp, Py_buffer *view);
+PyAPI_FUNC(int) _PyBuffer_ReleaseInInterpreterAndRawFree(
+        PyInterpreterState *interp, Py_buffer *view);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_INTERNAL_PYBUFFER_H */

Lib/test/support/interpreters.py

@@ -225,6 +225,21 @@ def send_nowait(self, obj):
         # See bpo-32604 and gh-19829.
         return _channels.send(self._id, obj)
 
+    def send_buffer(self, obj):
+        """Send the object's buffer to the channel's receiving end.
+
+        This blocks until the object is received.
+        """
+        _channels.send_buffer(self._id, obj)
+
+    def send_buffer_nowait(self, obj):
+        """Send the object's buffer to the channel's receiving end.
+
+        If the object is immediately received then return True
+        (else False).  Otherwise this is the same as send().
+        """
+        return _channels.send_buffer(self._id, obj)
+
     def close(self):
         _channels.close(self._id, send=True)
 

Lib/test/test__xxinterpchannels.py

@@ -703,6 +703,21 @@ def test_recv_sending_interp_destroyed(self):
                 channels.recv(cid2)
             del cid2
 
+    def test_send_buffer(self):
+        buf = bytearray(b'spamspamspam')
+        cid = channels.create()
+        channels.send_buffer(cid, buf)
+        obj = channels.recv(cid)
+
+        self.assertIsNot(obj, buf)
+        self.assertIsInstance(obj, memoryview)
+        self.assertEqual(obj, buf)
+
+        buf[4:8] = b'eggs'
+        self.assertEqual(obj, buf)
+        obj[4:8] = b'ham.'
+        self.assertEqual(obj, buf)
+
     def test_allowed_types(self):
         cid = channels.create()
         objects = [

Lib/test/test_interpreters.py

@@ -1067,3 +1067,46 @@ def test_recv_nowait_default(self):
         self.assertEqual(obj4, b'spam')
         self.assertEqual(obj5, b'eggs')
         self.assertIs(obj6, default)
+
+    def test_send_buffer(self):
+        buf = bytearray(b'spamspamspam')
+        obj = None
+        rch, sch = interpreters.create_channel()
+
+        def f():
+            nonlocal obj
+            while True:
+                try:
+                    obj = rch.recv()
+                    break
+                except interpreters.ChannelEmptyError:
+                    time.sleep(0.1)
+        t = threading.Thread(target=f)
+        t.start()
+
+        sch.send_buffer(buf)
+        t.join()
+
+        self.assertIsNot(obj, buf)
+        self.assertIsInstance(obj, memoryview)
+        self.assertEqual(obj, buf)
+
+        buf[4:8] = b'eggs'
+        self.assertEqual(obj, buf)
+        obj[4:8] = b'ham.'
+        self.assertEqual(obj, buf)
+
+    def test_send_buffer_nowait(self):
+        buf = bytearray(b'spamspamspam')
+        rch, sch = interpreters.create_channel()
+        sch.send_buffer_nowait(buf)
+        obj = rch.recv()
+
+        self.assertIsNot(obj, buf)
+        self.assertIsInstance(obj, memoryview)
+        self.assertEqual(obj, buf)
+
+        buf[4:8] = b'eggs'
+        self.assertEqual(obj, buf)
+        obj[4:8] = b'ham.'
+        self.assertEqual(obj, buf)

Makefile.pre.in

@@ -1791,6 +1791,7 @@ PYTHON_HEADERS= \
 		$(srcdir)/Include/internal/pycore_parking_lot.h \
 		$(srcdir)/Include/internal/pycore_pathconfig.h \
 		$(srcdir)/Include/internal/pycore_pyarena.h \
+		$(srcdir)/Include/internal/pycore_pybuffer.h \
 		$(srcdir)/Include/internal/pycore_pyerrors.h \
 		$(srcdir)/Include/internal/pycore_pyhash.h \
 		$(srcdir)/Include/internal/pycore_pylifecycle.h \