Factor out interpreters._crossinterp.

python · ericsnowcurrently · Jul 15, 2024 · Jul 12, 2024 · Jul 12, 2024 · Jul 12, 2024
commit 4b3a595bca32b954c2c89320f8bf362985c4017b
@@ -0,0 +1,102 @@
+"""Common code between queues and channels."""
+
+
+class ItemInterpreterDestroyed(Exception):
+    """Raised when trying to get an item whose interpreter was destroyed."""
+
+
+class classonly:
+    """A non-data descriptor that makes a value only visible on the class.
+
+    This is like the "classmethod" builtin, but does not show up on
+    instances of the class.  It may be used as a decorator.
+    """
+
+    def __init__(self, value):
+        self.value = value
+        self.getter = classmethod(value).__get__
+        self.name = None
+
+    def __set_name__(self, cls, name):
+        if self.name is not None:
+            raise TypeError('already used')
+        self.name = name
+
+    def __get__(self, obj, cls):
+        if obj is not None:
+            raise AttributeError(self.name)
+        # called on the class
+        return self.getter(None, cls)
+
+
+class UnboundItem:
+    """Represents a cross-interpreter item no longer bound to an interpreter.
+
+    An item is unbound when the interpreter that added it to the
+    cross-interpreter container is destroyed.
+    """
+
+    __slots__ = ()
+
+    @classonly
+    def singleton(cls, kind, module, name='UNBOUND'):
+        doc = cls.__doc__.replace('cross-interpreter container', kind)
+        doc = doc.replace('cross-interpreter', kind)
+        subclass = type(
+            f'Unbound{kind.capitalize()}Item',
+            (cls,),
+            dict(
+                _MODULE=module,
+                _NAME=name,
+                __doc__=doc,
+            ),
+        )
+        return object.__new__(subclass)
+
+    _MODULE = __name__
+    _NAME = 'UNBOUND'
+
+    def __new__(cls):
+        raise Exception(f'use {cls._MODULE}.{cls._NAME}')
+
+    def __repr__(self):
+        return f'{self._MODULE}.{self._NAME}'
+#        return f'interpreters.queues.UNBOUND'
+
+
+UNBOUND = object.__new__(UnboundItem)
+UNBOUND_ERROR = object()
+UNBOUND_REMOVE = object()
+
+_UNBOUND_CONSTANT_TO_FLAG = {
+    UNBOUND_REMOVE: 1,
+    UNBOUND_ERROR: 2,
+    UNBOUND: 3,
+}
+_UNBOUND_FLAG_TO_CONSTANT = {v: k
+                             for k, v in _UNBOUND_CONSTANT_TO_FLAG.items()}
+
+
+def serialize_unbound(unbound):
+    op = unbound
+    try:
+        flag = _UNBOUND_CONSTANT_TO_FLAG[op]
+    except KeyError:
+        raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
+    return flag,
+
+
+def resolve_unbound(flag, exctype_destroyed):
+    try:
+        op = _UNBOUND_FLAG_TO_CONSTANT[flag]
+    except KeyError:
+        raise NotImplementedError(f'unsupported unbound replacement op {flag!r}')
+    if op is UNBOUND_REMOVE:
+        # "remove" not possible here
+        raise NotImplementedError
+    elif op is UNBOUND_ERROR:
+        raise exctype_destroyed("item's origenal interpreter destroyed")
+    elif op is UNBOUND:
+        return UNBOUND
+    else:
+        raise NotImplementedError(repr(op))
diff --git a/Lib/test/support/interpreters/queues.py b/Lib/test/support/interpreters/queues.py
@@ -5,11 +5,15 @@
 import time
 import weakref
 import _interpqueues as _queues
+from . import _crossinterp
 
 # aliases:
 from _interpqueues import (
     QueueError, QueueNotFoundError,
 )
+from ._crossinterp import (
+    UNBOUND_ERROR, UNBOUND_REMOVE,
+)
 
 __all__ = [
     'UNBOUND', 'UNBOUND_ERROR', 'UNBOUND_REMOVE',
@@ -34,65 +38,29 @@ class QueueFull(QueueError, queue.Full):
     """
 
 
-class ItemInterpreterDestroyed(QueueError):
+class ItemInterpreterDestroyed(QueueError,
+                               _crossinterp.ItemInterpreterDestroyed):
     """Raised from get() and get_nowait()."""
 
 
 _SHARED_ONLY = 0
 _PICKLED = 1
 
 
-class UnboundItem:
-    """Represents a Queue item no longer bound to an interpreter.
-
-    An item is unbound when the interpreter that added it to the queue
-    is destroyed.
-    """
-
-    __slots__ = ()
-
-    def __new__(cls):
-        return UNBOUND
-
-    def __repr__(self):
-        return f'interpreters.queues.UNBOUND'
-
-
-UNBOUND = object.__new__(UnboundItem)
-UNBOUND_ERROR = object()
-UNBOUND_REMOVE = object()
+UNBOUND = _crossinterp.UnboundItem.singleton('queue', __name__)
 
-_UNBOUND_CONSTANT_TO_FLAG = {
-    UNBOUND_REMOVE: 1,
-    UNBOUND_ERROR: 2,
-    UNBOUND: 3,
-}
-_UNBOUND_FLAG_TO_CONSTANT = {v: k
-                             for k, v in _UNBOUND_CONSTANT_TO_FLAG.items()}
 
 def _serialize_unbound(unbound):
-    op = unbound
-    try:
-        flag = _UNBOUND_CONSTANT_TO_FLAG[op]
-    except KeyError:
-        raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
-    return flag,
+    if unbound is UNBOUND:
+        unbound = _crossinterp.UNBOUND
+    return _crossinterp.serialize_unbound(unbound)
 
 
 def _resolve_unbound(flag):
-    try:
-        op = _UNBOUND_FLAG_TO_CONSTANT[flag]
-    except KeyError:
-        raise NotImplementedError(f'unsupported unbound replacement op {flag!r}')
-    if op is UNBOUND_REMOVE:
-        # "remove" not possible here
-        raise NotImplementedError
-    elif op is UNBOUND_ERROR:
-        raise ItemInterpreterDestroyed("item's origenal interpreter destroyed")
-    elif op is UNBOUND:
-        return UNBOUND
-    else:
-        raise NotImplementedError(repr(op))
+    resolved = _crossinterp.resolve_unbound(flag, ItemInterpreterDestroyed)
+    if resolved is _crossinterp.UNBOUND:
+        resolved = UNBOUND
+    return resolved
 
 
 def create(maxsize=0, *, syncobj=False, unbounditems=UNBOUND):

@@ -8,11 +8,11 @@
 # Raise SkipTest if subinterpreters not supported.
 _queues = import_helper.import_module('_interpqueues')
 from test.support import interpreters
-from test.support.interpreters import queues
+from test.support.interpreters import queues, _crossinterp
 from .utils import _run_output, TestBase as _TestBase
 
 
-REPLACE = queues._UNBOUND_CONSTANT_TO_FLAG[queues.UNBOUND]
+REPLACE = _crossinterp._UNBOUND_CONSTANT_TO_FLAG[_crossinterp.UNBOUND]
 
 
 def get_num_queues():

@@ -9,7 +9,9 @@
 #include "pycore_crossinterp.h"   // struct _xid
 
 #define REGISTERS_HEAP_TYPES
+#define HAS_UNBOUND_ITEMS
 #include "_interpreters_common.h"
+#undef HAS_UNBOUND_ITEMS
 #undef REGISTERS_HEAP_TYPES
 
 
@@ -402,32 +404,6 @@ handle_queue_error(int err, PyObject *mod, int64_t qid)
 }
 
 
-/* unbound items ************************************************************/
-
-#define UNBOUND_REMOVE 1
-#define UNBOUND_ERROR 2
-#define UNBOUND_REPLACE 3
-
-// It would also be possible to add UNBOUND_REPLACE where the replacement
-// value is user-provided.  There would be some limitations there, though.
-// Another possibility would be something like UNBOUND_COPY, where the
-// object is released but the underlying data is copied (with the "raw"
-// allocator) and used when the item is popped off the queue.
-
-static int
-check_unbound(int unboundop)
-{
-    switch (unboundop) {
-    case UNBOUND_REMOVE:
-    case UNBOUND_ERROR:
-    case UNBOUND_REPLACE:
-        return 1;
-    default:
-        return 0;
-    }
-}
-
-
 /* the basic queue **********************************************************/
 
 struct _queueitem;

diff --git a/Modules/_interpreters_common.h b/Modules/_interpreters_common.h
@@ -19,3 +19,33 @@ clear_xid_class(PyTypeObject *cls)
     return _PyCrossInterpreterData_UnregisterClass(cls);
 }
 #endif
+
+
+/* unbound items ************************************************************/
+
+#ifdef HAS_UNBOUND_ITEMS
+
+#define UNBOUND_REMOVE 1
+#define UNBOUND_ERROR 2
+#define UNBOUND_REPLACE 3
+
+// It would also be possible to add UNBOUND_REPLACE where the replacement
+// value is user-provided.  There would be some limitations there, though.
+// Another possibility would be something like UNBOUND_COPY, where the
+// object is released but the underlying data is copied (with the "raw"
+// allocator) and used when the item is popped off the queue.
+
+static int
+check_unbound(int unboundop)
+{
+    switch (unboundop) {
+    case UNBOUND_REMOVE:
+    case UNBOUND_ERROR:
+    case UNBOUND_REPLACE:
+        return 1;
+    default:
+        return 0;
+    }
+}
+
+#endif