Upgrade Cython to version 3

While looking at #333, I hypothesized that upgrading Cython might solve the
issue. It didn't. But upgrading should still happen at some point. This is my
work in progress on that. The tests pass, but there are two main things missing:

Problem (1):
Starting with Cython 3, you can only do `except+` or `except
+reraise_kj_exception` on `extern` functions coming from C++. (This makes sense,
and the way things were declared in Pycapnp wasn't too good.) As a result, I had
to remove a lot of these declaration. This results in some segmentation faults,
because Cython no longer detects C++ exceptions and converts them to Python
exceptions in some places.

To solve this, all `extern` declarations in `.pxd` files have to be examined and
`except +reraise_kj_exception` clauses need to be added to anything that might
throw. Previously, this was done really inconsistently. The lazy solution would
be to just add the clause everywhere, but I'm not sure what the performance
implications are.

Problem (2):
The compilation output of `python setup.py build_ext --inplace` is now full of messages like these:
```
capnp/lib/capnp.cpp: In function ‘PyObject* __pyx_f_5capnp_3lib_5capnp_18_DynamicListReader__get(__pyx_obj_5capnp_3lib_5capnp__DynamicListReader*, int64_t, int)’:
capnp/lib/capnp.cpp:4871:51: warning: moving a temporary object prevents copy elision [-Wpessimizing-move]
 4871 |   #define __PYX_STD_MOVE_IF_SUPPORTED(x) std::move(x)
      |                                          ~~~~~~~~~^~~
capnp/lib/capnp.cpp:20944:59: note: in expansion of macro ‘__PYX_STD_MOVE_IF_SUPPORTED’
20944 |   __pyx_t_2 = __pyx_f_5capnp_3lib_5capnp_to_python_reader(__PYX_STD_MOVE_IF_SUPPORTED((( ::capnp::DynamicValue::Reader)__pyx_t_7)), __pyx_t_1); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 419, __pyx_L1_error)
      |                                                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~
capnp/lib/capnp.cpp:4871:51: note: remove ‘std::move’ call
 4871 |   #define __PYX_STD_MOVE_IF_SUPPORTED(x) std::move(x)
      |                                          ~~~~~~~~~^~~
capnp/lib/capnp.cpp:20944:59: note: in expansion of macro ‘__PYX_STD_MOVE_IF_SUPPORTED’
20944 |   __pyx_t_2 = __pyx_f_5capnp_3lib_5capnp_to_python_reader(__PYX_STD_MOVE_IF_SUPPORTED((( ::capnp::DynamicValue::Reader)__pyx_t_7)), __pyx_t_1); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 419, __pyx_L1_error)
      |                                                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```
There are to many `move` calls inserted. I'm not sure if this is a Cython issue,
or if we are somehow annotating things wrong. Might be worth asking the Cython
people.

I'm not planning on working on this further in the short term. If someone wants
to take over on this, feel free.

capnp/helpers/helpers.pxd

@@ -16,9 +16,6 @@ cdef extern from "capnp/helpers/fixMaybe.h":
 
 cdef extern from "capnp/helpers/capabilityHelper.h":
     PyPromise then(PyPromise promise, Own[PyRefCounter] func, Own[PyRefCounter] error_func)
-    DynamicCapability.Client new_client(InterfaceSchema&, PyObject *)
-    DynamicValue.Reader new_server(InterfaceSchema&, PyObject *)
-    Capability.Client server_to_client(InterfaceSchema&, PyObject *)
     PyPromise convert_to_pypromise(RemotePromise)
     PyPromise convert_to_pypromise(VoidPromise)
     VoidPromise taskToPromise(Own[PyRefCounter] coroutine, PyObject* callback)
@@ -26,11 +23,11 @@ cdef extern from "capnp/helpers/capabilityHelper.h":
     void init_capnp_api()
 
 cdef extern from "capnp/helpers/rpcHelper.h":
-    Capability.Client bootstrapHelper(RpcSystem&)
+    Own[Capability.Client] bootstrapHelper(RpcSystem&) except +reraise_kj_exception
-    Capability.Client bootstrapHelperServer(RpcSystem&)
+    Own[Capability.Client] bootstrapHelperServer(RpcSystem&) except +reraise_kj_exception
 
 cdef extern from "capnp/helpers/serialize.h":
-    ByteArray messageToPackedBytes(MessageBuilder &, size_t wordCount)
+    ByteArray messageToPackedBytes(MessageBuilder &, size_t wordCount) except +reraise_kj_exception
 
 cdef extern from "capnp/helpers/deserialize.h":
     Node.Reader toReader(DynamicStruct.Reader reader) except +reraise_kj_exception

capnp/helpers/rpcHelper.h

@@ -6,16 +6,16 @@
 #include "Python.h"
 #include "capabilityHelper.h"
 
-capnp::Capability::Client bootstrapHelper(capnp::RpcSystem<capnp::rpc::twoparty::SturdyRefHostId>& client) {
+kj::Own<capnp::Capability::Client> bootstrapHelper(capnp::RpcSystem<capnp::rpc::twoparty::SturdyRefHostId>& client) {
     capnp::MallocMessageBuilder hostIdMessage(8);
     auto hostId = hostIdMessage.initRoot<capnp::rpc::twoparty::SturdyRefHostId>();
     hostId.setSide(capnp::rpc::twoparty::Side::SERVER);
-    return client.bootstrap(hostId);
+    return kj::heap<capnp::Capability::Client>(client.bootstrap(hostId));
 }
 
-capnp::Capability::Client bootstrapHelperServer(capnp::RpcSystem<capnp::rpc::twoparty::SturdyRefHostId>& client) {
+kj::Own<capnp::Capability::Client> bootstrapHelperServer(capnp::RpcSystem<capnp::rpc::twoparty::SturdyRefHostId>& client) {
     capnp::MallocMessageBuilder hostIdMessage(8);
     auto hostId = hostIdMessage.initRoot<capnp::rpc::twoparty::SturdyRefHostId>();
     hostId.setSide(capnp::rpc::twoparty::Side::CLIENT);
-    return client.bootstrap(hostId);
+    return kj::heap<capnp::Capability::Client>(client.bootstrap(hostId));
 }

capnp/includes/capnp_cpp.pxd

@@ -57,26 +57,12 @@ cdef extern from "kj/async.h" namespace " ::kj":
     cdef cppclass Promise[T] nogil:
         Promise(Promise)
         Promise(T)
-        T wait(WaitScope) except +reraise_kj_exception
-        bool poll(WaitScope) except +reraise_kj_exception
-        # ForkedPromise<T> fork()
-        # Promise<T> exclusiveJoin(Promise<T>&& other)
-        # Promise[T] eagerlyEvaluate()
-        # void detach(ErrorFunc)
         String trace()
         Promise[T] attach(Own[PyRefCounter] &)
         Promise[T] attach(Own[PyRefCounter] &, Own[PyRefCounter] &)
         Promise[T] attach(Own[PyRefCounter] &, Own[PyRefCounter] &, Own[PyRefCounter] &)
         Promise[T] attach(Own[PyRefCounter] &, Own[PyRefCounter] &, Own[PyRefCounter] &, Own[PyRefCounter] &)
 
-    cdef cppclass Canceler nogil:
-        Canceler()
-        Promise[T] wrap[T](Promise[T] promise)
-        void cancel(StringPtr cancelReason)
-        void cancel(Exception& exception)
-        void release()
-        bool isEmpty()
-
 ctypedef Promise[Own[PyRefCounter]] PyPromise
 ctypedef Promise[void] VoidPromise
 
@@ -109,8 +95,8 @@ cdef extern from "kj/array.h" namespace " ::kj":
 
 cdef extern from "kj/async-io.h" namespace " ::kj":
     cdef cppclass AsyncIoStream nogil:
-        Promise[size_t] read(void*, size_t, size_t)
+        Promise[size_t] read(void*, size_t, size_t) except +reraise_kj_exception
-        Promise[void] write(const void*, size_t)
+        Promise[void] write(const void*, size_t) except +reraise_kj_exception
 
 cdef extern from "capnp/schema.capnp.h" namespace " ::capnp":
     enum TypeWhich" ::capnp::schema::Type::Which":
@@ -297,7 +283,7 @@ cdef extern from "capnp/dynamic.h" namespace " ::capnp":
             Client()
             Client(Client&)
             Client(Own[PythonInterfaceDynamicImpl])
-            Client upcast(InterfaceSchema requestedSchema)
+            Client upcast(InterfaceSchema requestedSchema) except +reraise_kj_exception
             DynamicCapability.Client castAs"castAs< ::capnp::DynamicCapability>"(InterfaceSchema)
             InterfaceSchema getSchema()
             Request newRequest(char * methodName)
@@ -448,7 +434,7 @@ cdef extern from "capnp/dynamic.h" namespace " ::capnp":
             Type getType()
 
 cdef extern from "capnp/schema-loader.h" namespace " ::capnp":
-    cdef cppclass SchemaLoader:
+    cdef cppclass SchemaLoader nogil:
         SchemaLoader()
         Schema load(Node.Reader reader) except +reraise_kj_exception
         Schema get(uint64_t id_) except +reraise_kj_exception

capnp/includes/schema_cpp.pxd

@@ -673,7 +673,7 @@ cdef extern from "capnp/message.h" namespace " ::capnp":
         Annotation.Builder getRootAnnotation'getRoot< ::capnp::schema::Annotation>'()
         Annotation.Builder initRootAnnotation'initRoot< ::capnp::schema::Annotation>'()
 
-        DynamicStruct_Builder getRootDynamicStruct'getRoot< ::capnp::DynamicStruct>'(StructSchema)
+        DynamicStruct_Builder getRootDynamicStruct'getRoot< ::capnp::DynamicStruct>'(StructSchema) except +reraise_kj_exception
         DynamicStruct_Builder initRootDynamicStruct'initRoot< ::capnp::DynamicStruct>'(StructSchema)
         void setRootDynamicStruct'setRoot< ::capnp::DynamicStruct::Reader>'(DynamicStruct.Reader)
 
@@ -696,7 +696,7 @@ cdef extern from "capnp/message.h" namespace " ::capnp":
         StructNode.Reader getRootStructNode'getRoot< ::capnp::schema::StructNode>'()
         Annotation.Reader getRootAnnotation'getRoot< ::capnp::schema::Annotation>'()
 
-        DynamicStruct.Reader getRootDynamicStruct'getRoot< ::capnp::DynamicStruct>'(StructSchema)
+        DynamicStruct.Reader getRootDynamicStruct'getRoot< ::capnp::DynamicStruct>'(StructSchema) except +reraise_kj_exception
         AnyPointer.Reader getRootAnyPointer'getRoot< ::capnp::AnyPointer>'()
 
     cdef cppclass MallocMessageBuilder(MessageBuilder) nogil:
@@ -798,7 +798,7 @@ cdef extern from "capnp/serialize.h" namespace " ::capnp":
         FlatArrayMessageReader(WordArrayPtr array, ReaderOptions) except +reraise_kj_exception
         const word* getEnd() const
 
-    void writeMessageToFd(int, MessageBuilder&) nogil except +reraise_kj_exception
+    void writeMessageToFd(int, MessageBuilder&) except +reraise_kj_exception nogil
 
     WordArray messageToFlatArray(MessageBuilder &) nogil
 
@@ -816,6 +816,6 @@ cdef extern from "capnp/serialize-packed.h" namespace " ::capnp":
         PackedFdMessageReader(int) except +reraise_kj_exception
         PackedFdMessageReader(int, ReaderOptions) except +reraise_kj_exception
 
-    void writePackedMessage(BufferedOutputStream&, MessageBuilder&) nogil except +reraise_kj_exception
+    void writePackedMessage(BufferedOutputStream&, MessageBuilder&) except +reraise_kj_exception nogil
-    void writePackedMessage(OutputStream&, MessageBuilder&) nogil except +reraise_kj_exception
+    void writePackedMessage(OutputStream&, MessageBuilder&) except +reraise_kj_exception nogil
-    void writePackedMessageToFd(int, MessageBuilder&) nogil except +reraise_kj_exception
+    void writePackedMessageToFd(int, MessageBuilder&) except +reraise_kj_exception nogil

capnp/lib/capnp.pxd

@@ -28,7 +28,7 @@ cdef class _StringArrayPtr:
     cdef StringPtr * thisptr
     cdef object parent
     cdef size_t size
-    cdef ArrayPtr[StringPtr] asArrayPtr(self) except +reraise_kj_exception
+    cdef ArrayPtr[StringPtr] asArrayPtr(self)
 
 cdef class SchemaLoader:
     cdef C_SchemaLoader * thisptr
@@ -38,7 +38,7 @@ cdef class SchemaParser:
     cdef public dict modules_by_id
     cdef list _all_imports
     cdef _StringArrayPtr _last_import_array
-    cpdef _parse_disk_file(self, displayName, diskPath, imports) except +reraise_kj_exception
+    cpdef _parse_disk_file(self, displayName, diskPath, imports)
 
 cdef class _DynamicOrphan:
     cdef C_DynamicOrphan thisptr
@@ -79,10 +79,10 @@ cdef class _DynamicStructBuilder:
     cdef _init(self, DynamicStruct_Builder other, object parent, bint isRoot=?, bint tryRegistry=?)
 
     cdef _check_write(self)
-    cpdef to_bytes(_DynamicStructBuilder self) except +reraise_kj_exception
+    cpdef to_bytes(_DynamicStructBuilder self)
-    cpdef to_segments(_DynamicStructBuilder self) except +reraise_kj_exception
+    cpdef to_segments(_DynamicStructBuilder self)
-    cpdef _to_bytes_packed_helper(_DynamicStructBuilder self, word_count) except +reraise_kj_exception
+    cpdef _to_bytes_packed_helper(_DynamicStructBuilder self, word_count)
-    cpdef to_bytes_packed(_DynamicStructBuilder self) except +reraise_kj_exception
+    cpdef to_bytes_packed(_DynamicStructBuilder self)
 
     cpdef _get(self, field)
     cpdef _set(self, field, value)
@@ -128,7 +128,7 @@ cdef class _DynamicEnum:
     cdef public object _parent
 
     cdef _init(self, capnp.DynamicEnum other, object parent)
-    cpdef _as_str(self) except +reraise_kj_exception
+    cpdef _as_str(self)
 
 cdef class _DynamicListBuilder:
     cdef C_DynamicList.Builder thisptr
@@ -146,11 +146,11 @@ cdef class _DynamicListBuilder:
 cdef class _MessageBuilder:
     cdef schema_cpp.MessageBuilder * thisptr
     cpdef init_root(self, schema)
-    cpdef get_root(self, schema) except +reraise_kj_exception
+    cpdef get_root(self, schema)
-    cpdef get_root_as_any(self) except +reraise_kj_exception
+    cpdef get_root_as_any(self)
-    cpdef set_root(self, value) except +reraise_kj_exception
+    cpdef set_root(self, value)
-    cpdef get_segments_for_output(self) except +reraise_kj_exception
+    cpdef get_segments_for_output(self)
-    cpdef new_orphan(self, schema) except +reraise_kj_exception
+    cpdef new_orphan(self, schema)
 
 cdef to_python_reader(C_DynamicValue.Reader self, object parent)
 cdef to_python_builder(C_DynamicValue.Builder self, object parent)

capnp/lib/capnp.pyx

@@ -10,11 +10,12 @@
 cimport cython  # noqa: E402
 
 from capnp.helpers.helpers cimport init_capnp_api
-from capnp.includes.capnp_cpp cimport AsyncIoStream, WaitScope, PyPromise, VoidPromise, EventPort, EventLoop, Canceler, PyAsyncIoStream, PromiseFulfiller, VoidPromiseFulfiller, tryReadMessage, writeMessage, makeException, PythonInterfaceDynamicImpl
+from capnp.includes.capnp_cpp cimport AsyncIoStream, WaitScope, PyPromise, VoidPromise, EventPort, EventLoop, PyAsyncIoStream, PromiseFulfiller, VoidPromiseFulfiller, tryReadMessage, writeMessage, makeException, PythonInterfaceDynamicImpl
 from capnp.includes.schema_cpp cimport (MessageReader,)
 
-from cpython cimport array, Py_buffer, PyObject_CheckBuffer, memoryview, buffer
+from cpython cimport array, Py_buffer, PyObject_CheckBuffer
-from cpython.buffer cimport PyBUF_SIMPLE, PyBUF_WRITABLE
+from cpython.buffer cimport PyBUF_SIMPLE, PyBUF_WRITABLE, PyBUF_WRITE, PyBUF_READ
+from cpython.memoryview cimport PyMemoryView_FromMemory
 from cpython.exc cimport PyErr_Clear
 from cython.operator cimport dereference as deref
 from libc.stdlib cimport malloc, free
@@ -129,10 +130,10 @@ def fill_context(method_name, context, returned_data):
     for arg_name, arg_val in zip(names, returned_data):
         setattr(results, arg_name, arg_val)
 
-cdef api VoidPromise * call_server_method(object server,
+cdef api Promise[void]* call_server_method(object server,
                                           char * _method_name,
                                           CallContext & _context,
-                                          object _kj_loop) except * with gil:
+                                          object _kj_loop) except* with gil:
     method_name = <object>_method_name
     kj_loop = <_EventLoop>_kj_loop
     kj_loop.check()
@@ -303,7 +304,7 @@ cdef api object get_exception_info(object exc_type, object exc_obj, object exc_t
         return (b'', 0, b"Couldn't determine python exception")
 
 
-cdef schema_cpp.ReaderOptions make_reader_opts(traversal_limit_in_words, nesting_limit) with gil:
+cdef schema_cpp.ReaderOptions make_reader_opts(traversal_limit_in_words, nesting_limit):
     cdef schema_cpp.ReaderOptions opts
     if traversal_limit_in_words is not None:
         opts.traversalLimitInWords = traversal_limit_in_words
@@ -1029,7 +1030,7 @@ cdef class _DynamicEnum:
         self._parent = parent
         return self
 
-    cpdef _as_str(self) except +reraise_kj_exception:
+    cpdef _as_str(self):
         return <char*>helpers.fixMaybe(self.thisptr.getEnumerant()).getProto().getName().cStr()
 
     property raw:
@@ -1339,7 +1340,7 @@ cdef class _DynamicStructBuilder:
         _write_packed_message_to_fd(file.fileno(), self._parent)
         self._is_written = True
 
-    cpdef to_bytes(_DynamicStructBuilder self) except +reraise_kj_exception:
+    cpdef to_bytes(_DynamicStructBuilder self):
         """Returns the struct's containing message as a Python bytes object in the unpacked binary format.
 
         This is inefficient; it makes several copies.
@@ -1356,7 +1357,7 @@ cdef class _DynamicStructBuilder:
         self._is_written = True
         return ret
 
-    cpdef to_segments(_DynamicStructBuilder self) except +reraise_kj_exception:
+    cpdef to_segments(_DynamicStructBuilder self):
         """Returns the struct's containing message as a Python list of Python bytes objects.
 
         This avoids making copies.
@@ -1370,14 +1371,14 @@ cdef class _DynamicStructBuilder:
         segments = builder.get_segments_for_output()
         return segments
 
-    cpdef _to_bytes_packed_helper(_DynamicStructBuilder self, word_count) except +reraise_kj_exception:
+    cpdef _to_bytes_packed_helper(_DynamicStructBuilder self, word_count):
         cdef _MessageBuilder builder = self._parent
         array = helpers.messageToPackedBytes(deref(builder.thisptr), word_count)
         cdef const char* ptr = <const char *>array.begin()
         cdef bytes ret = ptr[:array.size()]
         return ret
 
-    cpdef to_bytes_packed(_DynamicStructBuilder self) except +reraise_kj_exception:
+    cpdef to_bytes_packed(_DynamicStructBuilder self):
         self._check_write()
         word_count = self.total_size.word_count + 2
 
@@ -1649,7 +1650,7 @@ cdef class _DynamicStructPipeline:
     def __dealloc__(self):
         del self.thisptr
 
-    cpdef _get(self, field) except +reraise_kj_exception:
+    cpdef _get(self, field):
         cdef int type = (<C_DynamicValue.Pipeline>self.thisptr.get(field)).getType()
         if type == capnp.TYPE_CAPABILITY:
             return _DynamicCapabilityClient()._init(
@@ -1719,7 +1720,7 @@ cdef class _DynamicObjectReader:
         self._parent = parent
         return self
 
-    cpdef as_struct(self, schema) except +reraise_kj_exception:
+    cpdef as_struct(self, schema):
         cdef _StructSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1728,7 +1729,7 @@ cdef class _DynamicObjectReader:
 
         return _DynamicStructReader()._init(self.thisptr.getAs(s._thisptr()), self._parent)
 
-    cpdef as_interface(self, schema) except +reraise_kj_exception:
+    cpdef as_interface(self, schema):
         cdef _InterfaceSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1737,7 +1738,7 @@ cdef class _DynamicObjectReader:
 
         return _DynamicCapabilityClient()._init(self.thisptr.getAsCapability(s.thisptr), self._parent)
 
-    cpdef as_list(self, schema) except +reraise_kj_exception:
+    cpdef as_list(self, schema):
         cdef _ListSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1746,7 +1747,7 @@ cdef class _DynamicObjectReader:
 
         return _DynamicListReader()._init(self.thisptr.getAsList(s.thisptr), self._parent)
 
-    cpdef as_text(self) except +reraise_kj_exception:
+    cpdef as_text(self):
         return (<char*>self.thisptr.getAsText().cStr())[:]
 
 
@@ -1762,7 +1763,7 @@ cdef class _DynamicObjectBuilder:
     def __dealloc__(self):
         del self.thisptr
 
-    cpdef as_struct(self, schema) except +reraise_kj_exception:
+    cpdef as_struct(self, schema):
         cdef _StructSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1771,7 +1772,7 @@ cdef class _DynamicObjectBuilder:
 
         return _DynamicStructBuilder()._init(self.thisptr.getAs(s._thisptr()), self._parent)
 
-    cpdef as_interface(self, schema) except +reraise_kj_exception:
+    cpdef as_interface(self, schema):
         cdef _InterfaceSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1780,7 +1781,7 @@ cdef class _DynamicObjectBuilder:
 
         return _DynamicCapabilityClient()._init(self.thisptr.getAsCapability(s.thisptr), self._parent)
 
-    cpdef as_list(self, schema) except +reraise_kj_exception:
+    cpdef as_list(self, schema):
         cdef _ListSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -1806,13 +1807,13 @@ cdef class _DynamicObjectBuilder:
 
         return _DynamicListBuilder()._init(self.thisptr.initAsList(s.thisptr, size), self._parent)
 
-    cpdef as_text(self) except +reraise_kj_exception:
+    cpdef as_text(self):
         return (<char*>self.thisptr.getAsText().cStr())[:]
 
     cpdef as_reader(self):
         return _DynamicObjectReader()._init(self.thisptr.asReader(), self._parent)
 
-cdef void kjloop_runnable_callback(void* data) with gil:
+cdef kjloop_runnable_callback(void* data):
     cdef AsyncIoEventPort *port = <AsyncIoEventPort*>data
     assert port.runHandle is not None
     port.kjLoop.run()
@@ -1872,7 +1873,7 @@ cdef class _EventLoop:
     cdef object active_tasks
     cdef cbool closed
 
-    cdef _init(self, asyncio_loop) except +reraise_kj_exception:
+    cdef _init(self, asyncio_loop):
         self.event_port = capnp.heap[AsyncIoEventPort](<PyObject*>asyncio_loop)
         kj_loop = deref(self.event_port).getKjLoop()
         self.wait_scope = capnp.heap[WaitScope](deref(kj_loop))
@@ -2007,7 +2008,7 @@ cdef class _Promise:
         self.thisptr = capnp.heap[PyPromise](move(other))
         return self
 
-    cpdef cancel(self) except +reraise_kj_exception:
+    cpdef cancel(self):
         self.thisptr = Own[PyPromise]()
 
 
@@ -2022,7 +2023,7 @@ cdef class _RemotePromise:
         self._parent = parent
         return self
 
-    cdef void _check_consumed(self) except*:
+    cdef _check_consumed(self):
         if self.thisptr.get() == NULL:
             raise KjException(
                 "Promise was already used in a consuming operation. You can no longer use this Promise object")
@@ -2035,7 +2036,7 @@ cdef class _RemotePromise:
             .attach(capnp.heap[PyRefCounter](<PyObject*>self._parent))
             ).__await__()
 
-    cpdef _get(self, field) except +reraise_kj_exception:
+    cpdef _get(self, field):
         self._check_consumed()
         cdef int type = (<C_DynamicValue.Pipeline>self.thisptr.get().get(field)).getType()
         if type == capnp.TYPE_CAPABILITY:
@@ -2068,7 +2069,7 @@ cdef class _RemotePromise:
     def to_dict(self, verbose=False, ordered=False):
         return _to_dict(self, verbose, ordered)
 
-    cpdef cancel(self) except +reraise_kj_exception:
+    cpdef cancel(self):
         self.thisptr = Own[RemotePromise]()
         self._parent = None # We don't need parent anymore. Setting to none allows quicker garbage collection
 
@@ -2171,7 +2172,7 @@ cdef class _DynamicCapabilityClient:
             for key, val in kwargs.items():
                 _setDynamicField(<DynamicStruct_Builder>deref(request), key, val, self)
 
-    cpdef _send_helper(self, name, word_count, args, kwargs) except +reraise_kj_exception:
+    cpdef _send_helper(self, name, word_count, args, kwargs):
         # if word_count is None:
         #     word_count = 0
         C_DEFAULT_EVENT_LOOP_GETTER() # Make sure the event loop is running
@@ -2181,7 +2182,7 @@ cdef class _DynamicCapabilityClient:
 
         return _RemotePromise()._init(request.send(), self)
 
-    cpdef _request_helper(self, name, firstSegmentWordSize, args, kwargs) except +reraise_kj_exception:
+    cpdef _request_helper(self, name, firstSegmentWordSize, args, kwargs):
         # if word_count is None:
         #     word_count = 0
         cdef _Request req = _Request()._init_child(self.thisptr.newRequest(name), self)
@@ -2210,7 +2211,7 @@ cdef class _DynamicCapabilityClient:
         except KjException as e:
             raise e._to_python() from None
 
-    cpdef upcast(self, schema) except +reraise_kj_exception:
+    cpdef upcast(self, schema):
         cdef _InterfaceSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -2219,7 +2220,7 @@ cdef class _DynamicCapabilityClient:
 
         return _DynamicCapabilityClient()._init(self.thisptr.upcast(s.thisptr), self._parent)
 
-    cpdef cast_as(self, schema) except +reraise_kj_exception:
+    cpdef cast_as(self, schema):
         cdef _InterfaceSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
@@ -2239,24 +2240,21 @@ cdef class _DynamicCapabilityClient:
 
 
 cdef class _CapabilityClient:
-    cdef C_Capability.Client * thisptr
+    cdef Own[C_Capability.Client] thisptr
     cdef public object _parent
 
-    cdef _init(self, C_Capability.Client other, object parent):
+    cdef _init(self, Own[C_Capability.Client] other, object parent):
-        self.thisptr = new C_Capability.Client(other)
+        self.thisptr = move(other)
         self._parent = parent
         return self
 
-    def __dealloc__(self):
-        del self.thisptr
-
     cpdef cast_as(self, schema):
         cdef _InterfaceSchema s
         if hasattr(schema, 'schema'):
             s = schema.schema
         else:
             s = schema
-        return _DynamicCapabilityClient()._init(self.thisptr.castAs(s.thisptr), self._parent)
+        return _DynamicCapabilityClient()._init(deref(self.thisptr).castAs(s.thisptr), self._parent)
 
 
 cdef class _TwoPartyVatNetwork:
@@ -2271,7 +2269,7 @@ cdef class _TwoPartyVatNetwork:
         self.thisptr = capnp.heap[C_TwoPartyVatNetwork](deref(stream.thisptr), side, opts)
         return self
 
-    cpdef on_disconnect(self) except +reraise_kj_exception:
+    cpdef on_disconnect(self):
         return _voidpromise_to_asyncio(deref(self.thisptr).onDisconnect())
 
 
@@ -2310,12 +2308,12 @@ cdef class TwoPartyClient:
 
         self.thisptr = capnp.heap[RpcSystem](makeRpcClient(deref(self._network.thisptr)))
 
-    cpdef bootstrap(self) except +reraise_kj_exception:
+    cpdef bootstrap(self):
         if self.closed:
             raise RuntimeError("This client is closed")
         return _CapabilityClient()._init(helpers.bootstrapHelper(deref(self.thisptr)), self)
 
-    cpdef on_disconnect(self) except +reraise_kj_exception:
+    cpdef on_disconnect(self):
         if self.closed:
             raise RuntimeError("This client is closed")
         return self._network.on_disconnect()
@@ -2365,12 +2363,12 @@ cdef class TwoPartyServer:
                 capnp.heap[PyRefCounter](<PyObject*>bootstrap),
                 capnp.heap[PyRefCounter](<PyObject*>loop)))))
 
-    cpdef bootstrap(self) except +reraise_kj_exception:
+    cpdef bootstrap(self):
         if self.closed:
             raise RuntimeError("This server is closed")
         return _CapabilityClient()._init(helpers.bootstrapHelperServer(deref(self.thisptr)), self)
 
-    cpdef on_disconnect(self) except +reraise_kj_exception:
+    cpdef on_disconnect(self):
         if self.closed:
             raise RuntimeError("This server is closed")
         return _voidpromise_to_asyncio(deref(self._network.thisptr).onDisconnect()
@@ -2581,7 +2579,7 @@ cdef class _PyAsyncIoStreamProtocol(DummyBaseClass, asyncio.BufferedProtocol):
             self.read_overflow_buffer_current = bytearray(size)
             return self.read_overflow_buffer_current
         else:
-            return memoryview.PyMemoryView_FromMemory(self.read_buffer, self.read_max_bytes, buffer.PyBUF_WRITE)
+            return PyMemoryView_FromMemory(self.read_buffer, self.read_max_bytes, PyBUF_WRITE)
 
     def buffer_updated(self, size):
         if self.read_buffer == NULL: # Should not happen, but for SSL it does, see comment above
@@ -2613,7 +2611,7 @@ cdef class _PyAsyncIoStreamProtocol(DummyBaseClass, asyncio.BufferedProtocol):
         cdef const ArrayPtr[const uint8_t]* piece
         for i in range(self.write_index, self.write_pieces.size()):
             piece = &self.write_pieces[i]
-            view = memoryview.PyMemoryView_FromMemory(<char*>piece.begin(), piece.size(), buffer.PyBUF_READ)
+            view = PyMemoryView_FromMemory(<char*>piece.begin(), piece.size(), PyBUF_READ)
             self.transport.write(view)
             if self.write_paused:
                 self.write_index = i+1
@@ -2667,7 +2665,7 @@ cdef api void _asyncio_stream_read_start(
     # Begin of draining the overflow buffer, which is created because of a bug in SSL, see comment above.
     # Can be removed once Python < 3.11 is not longer supported.
     if self.read_overflow_buffer:
-        to_copy = min(len(self.read_overflow_buffer), max_bytes)
+        to_copy = min(<size_t>len(self.read_overflow_buffer), max_bytes)
         memcpy(buffer, <char*>self.read_overflow_buffer, to_copy)
         del self.read_overflow_buffer[:to_copy]
         self.read_buffer += to_copy
@@ -3401,7 +3399,7 @@ cdef class _StringArrayPtr:
     def __dealloc__(self):
         free(self.thisptr)
 
-    cdef ArrayPtr[StringPtr] asArrayPtr(self) except +reraise_kj_exception:
+    cdef ArrayPtr[StringPtr] asArrayPtr(self):
         return ArrayPtr[StringPtr](self.thisptr, self.size)
 
 
@@ -3448,7 +3446,7 @@ cdef class SchemaParser:
     def __dealloc__(self):
         del self.thisptr
 
-    cpdef _parse_disk_file(self, displayName, diskPath, imports) except +reraise_kj_exception:
+    cpdef _parse_disk_file(self, displayName, diskPath, imports):
         cdef _StringArrayPtr importArray
 
         if self._last_import_array and self._last_import_array.parent == imports:
@@ -3616,7 +3614,7 @@ cdef class _MessageBuilder:
             s = schema
         return _DynamicStructBuilder()._init(self.thisptr.initRootDynamicStruct(s._thisptr()), self, True)
 
-    cpdef get_root(self, schema) except +reraise_kj_exception:
+    cpdef get_root(self, schema):
         """A method for instantiating Cap'n Proto structs, from an already pre-written buffer
 
         Don't use this method unless you know what you're doing. You probably
@@ -3641,7 +3639,7 @@ cdef class _MessageBuilder:
             s = schema
         return _DynamicStructBuilder()._init(self.thisptr.getRootDynamicStruct(s._thisptr()), self, True)
 
-    cpdef get_root_as_any(self) except +reraise_kj_exception:
+    cpdef get_root_as_any(self):
         """A method for getting a Cap'n Proto AnyPointer, from an already pre-written buffer
 
         Don't use this method unless you know what you're doing.
@@ -3651,7 +3649,7 @@ cdef class _MessageBuilder:
         """
         return _DynamicObjectBuilder()._init(self.thisptr.getRootAnyPointer(), self)
 
-    cpdef set_root(self, value) except +reraise_kj_exception:
+    cpdef set_root(self, value):
         """A method for instantiating Cap'n Proto structs by copying from an existing struct
 
         :type value: :class:`_DynamicStructReader`
@@ -3667,7 +3665,7 @@ cdef class _MessageBuilder:
             self.thisptr.setRootDynamicStruct((<_DynamicStructReader>value).thisptr)
             return self.get_root(value.schema)
 
-    cpdef get_segments_for_output(self) except +reraise_kj_exception:
+    cpdef get_segments_for_output(self):
         segments = self.thisptr.getSegmentsForOutput()
         res = []
         cdef const char* ptr
@@ -3679,7 +3677,7 @@ cdef class _MessageBuilder:
             res.append(segment_bytes)
         return res
 
-    cpdef new_orphan(self, schema) except +reraise_kj_exception:
+    cpdef new_orphan(self, schema):
         """A method for instantiating Cap'n Proto orphans
 
         Don't use this method unless you know what you're doing.
@@ -3737,7 +3735,7 @@ cdef class _MessageReader:
     def __init__(self):
         raise NotImplementedError("This is an abstract base class")
 
-    cpdef get_root(self, schema) except +reraise_kj_exception:
+    cpdef get_root(self, schema):
         """A method for instantiating Cap'n Proto structs
 
         You will need to pass in a schema to specify which struct to
@@ -3761,7 +3759,7 @@ cdef class _MessageReader:
             s = schema
         return _DynamicStructReader()._init(self.thisptr.getRootDynamicStruct(s._thisptr()), self)
 
-    cpdef get_root_as_any(self) except +reraise_kj_exception:
+    cpdef get_root_as_any(self):
         """A method for getting a Cap'n Proto AnyPointer, from an already pre-written buffer
 
         Don't use this method unless you know what you're doing.

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["setuptools", "wheel", "pkgconfig", "cython<3"]
+requires = ["setuptools", "wheel", "pkgconfig", "cython>=3.0"]
 build-backend = "backend"
 backend-path = ["_custom_build"]
 

requirements.txt

@@ -1,6 +1,6 @@
 jinja2
 black
-cython<3
+cython>=3
 flake8
 setuptools
 pkgconfig

tox.ini

@@ -8,7 +8,7 @@ deps=
     Jinja2
     pytest
     pytest-asyncio
-    cython<3
+    cython>=3
 
 commands =
     pip install .