Python 3.8 support

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.9', '3.10', '3.11', '3.12']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12']
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python }}

pyproject.toml

@@ -7,7 +7,7 @@ name = "dispatch-py"
 description = "Develop reliable distributed systems on the Dispatch platform."
 readme = "README.md"
 dynamic = ["version"]
-requires-python = ">= 3.9"
+requires-python = ">= 3.8"
 dependencies = [
     "grpcio >= 1.60.0",
     "protobuf >= 4.24.0",

src/dispatch/coroutine.py

@@ -1,6 +1,6 @@
 from dataclasses import dataclass
 from types import coroutine
-from typing import Any, Awaitable
+from typing import Any, Awaitable, List, Tuple
 
 from dispatch.experimental.durable import durable
 from dispatch.proto import Call
@@ -16,14 +16,14 @@ def call(call: Call) -> Any:
 
 @coroutine
 @durable
-def gather(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
+def gather(*awaitables: Awaitable[Any]) -> List[Any]:  # type: ignore[misc]
     """Alias for all."""
     return all(*awaitables)
 
 
 @coroutine
 @durable
-def all(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
+def all(*awaitables: Awaitable[Any]) -> List[Any]:  # type: ignore[misc]
     """Concurrently run a set of coroutines, blocking until all coroutines
     return or any coroutine raises an error. If any coroutine fails with an
     uncaught exception, the exception will be re-raised here."""
@@ -32,7 +32,7 @@ def all(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
 
 @coroutine
 @durable
-def any(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
+def any(*awaitables: Awaitable[Any]) -> List[Any]:  # type: ignore[misc]
     """Concurrently run a set of coroutines, blocking until any coroutine
     returns or all coroutines raises an error. If all coroutines fail with
     uncaught exceptions, the exception(s) will be re-raised here."""
@@ -41,7 +41,7 @@ def any(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
 
 @coroutine
 @durable
-def race(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
+def race(*awaitables: Awaitable[Any]) -> List[Any]:  # type: ignore[misc]
     """Concurrently run a set of coroutines, blocking until any coroutine
     returns or raises an error. If any coroutine fails with an uncaught
     exception, the exception will be re-raised here."""
@@ -50,17 +50,17 @@ def race(*awaitables: Awaitable[Any]) -> list[Any]:  # type: ignore[misc]
 
 @dataclass
 class AllDirective:
-    awaitables: tuple[Awaitable[Any], ...]
+    awaitables: Tuple[Awaitable[Any], ...]
 
 
 @dataclass
 class AnyDirective:
-    awaitables: tuple[Awaitable[Any], ...]
+    awaitables: Tuple[Awaitable[Any], ...]
 
 
 @dataclass
 class RaceDirective:
-    awaitables: tuple[Awaitable[Any], ...]
+    awaitables: Tuple[Awaitable[Any], ...]
 
 
 class AnyException(RuntimeError):
@@ -69,7 +69,7 @@ class AnyException(RuntimeError):
 
     __slots__ = ("exceptions",)
 
-    def __init__(self, exceptions: list[Exception]):
+    def __init__(self, exceptions: List[Exception]):
         self.exceptions = exceptions
 
     def __str__(self):

src/dispatch/experimental/durable/frame.c

@@ -6,11 +6,12 @@
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
 
-#if PY_MAJOR_VERSION != 3 || (PY_MINOR_VERSION < 9 || PY_MINOR_VERSION > 13)
-# error Python 3.9-3.13 is required
+#if PY_MAJOR_VERSION != 3 || (PY_MINOR_VERSION < 8 || PY_MINOR_VERSION > 13)
+# error Python 3.8-3.13 is required
 #endif
 
 // This is a redefinition of the private PyTryBlock from <= 3.10.
+// https://github.com/python/cpython/blob/3.8/Include/frameobject.h#L10
 // https://github.com/python/cpython/blob/3.9/Include/cpython/frameobject.h#L11
 // https://github.com/python/cpython/blob/3.10/Include/cpython/frameobject.h#L22
 typedef struct {
@@ -19,7 +20,8 @@ typedef struct {
     int b_level;
 } PyTryBlock;
 
-// This is a redefinition of the private PyCoroWrapper from 3.9-3.13.
+// This is a redefinition of the private PyCoroWrapper from 3.8-3.13.
+// https://github.com/python/cpython/blob/3.8/Objects/genobject.c#L840
 // https://github.com/python/cpython/blob/3.9/Objects/genobject.c#L830
 // https://github.com/python/cpython/blob/3.10/Objects/genobject.c#L884
 // https://github.com/python/cpython/blob/3.11/Objects/genobject.c#L1016
@@ -53,7 +55,9 @@ static int get_frame_iblock(Frame *frame);
 static void set_frame_iblock(Frame *frame, int iblock);
 static PyTryBlock *get_frame_blockstack(Frame *frame);
 
-#if PY_MINOR_VERSION == 9
+#if PY_MINOR_VERSION == 8
+#include "frame308.h"
+#elif PY_MINOR_VERSION == 9
 #include "frame309.h"
 #elif PY_MINOR_VERSION == 10
 #include "frame310.h"

src/dispatch/experimental/durable/frame308.h

@@ -0,0 +1,145 @@
+// This is a redefinition of the private/opaque frame object.
+//
+// https://github.com/python/cpython/blob/3.8/Include/frameobject.h#L16
+//
+// In Python <= 3.10, `struct _frame` is both the PyFrameObject and
+// PyInterpreterFrame. From Python 3.11 onwards, the two were split with the
+// PyFrameObject (struct _frame) pointing to struct _PyInterpreterFrame.
+struct Frame {
+    PyObject_VAR_HEAD
+    struct Frame *f_back; // struct _frame
+    PyCodeObject *f_code;
+    PyObject *f_builtins;
+    PyObject *f_globals;
+    PyObject *f_locals;
+    PyObject **f_valuestack;
+    PyObject **f_stacktop;
+    PyObject *f_trace;
+    char f_trace_lines;
+    char f_trace_opcodes;
+    PyObject *f_gen;
+    int f_lasti;
+    int f_lineno;
+    int f_iblock;
+    char f_executing;
+    PyTryBlock f_blockstack[CO_MAXBLOCKS];
+    PyObject *f_localsplus[1];
+};
+
+// Python 3.9 and prior didn't have an explicit enum of frame states,
+// but we can derive them based on the presence of a frame, and other
+// information found on the frame, for compatibility with later versions.
+typedef enum _framestate {
+    FRAME_CREATED = -2,
+    FRAME_EXECUTING = 0,
+    FRAME_CLEARED = 4
+} FrameState;
+
+/*
+// This is the definition of PyGenObject for reference to developers
+// working on the extension.
+//
+// Note that PyCoroObject and PyAsyncGenObject have the same layout as
+// PyGenObject, however the struct fields have a cr_ and ag_ prefix
+// (respectively) rather than a gi_ prefix. In Python <= 3.10, PyCoroObject
+// and PyAsyncGenObject have extra fields compared to PyGenObject. In Python
+// 3.11 onwards, the three objects are identical (except for field name
+// prefixes). The extra fields in Python <= 3.10 are not applicable to the
+// extension at this time.
+//
+// https://github.com/python/cpython/blob/3.8/Include/genobject.h#L17
+typedef struct {
+    PyObject_HEAD
+    PyFrameObject *gi_frame;
+    char gi_running;
+    PyObject *gi_code;
+    PyObject *gi_weakreflist;
+    PyObject *gi_name;
+    PyObject *gi_qualname;
+    _PyErr_StackItem gi_exc_state;
+} PyGenObject;
+*/
+
+static Frame *get_frame(PyGenObject *gen_like) {
+    Frame *frame = (Frame *)(gen_like->gi_frame);
+    assert(frame);
+    return frame;
+}
+
+static PyCodeObject *get_frame_code(Frame *frame) {
+    PyCodeObject *code = frame->f_code;
+    assert(code);
+    return code;
+}
+
+static int get_frame_lasti(Frame *frame) {
+    return frame->f_lasti;
+}
+
+static void set_frame_lasti(Frame *frame, int lasti) {
+    frame->f_lasti = lasti;
+}
+
+static int get_frame_state(PyGenObject *gen_like) {
+    // Python 3.8 doesn't have frame states, but we can derive
+    // some for compatibility with later versions and to simplify
+    // the extension.
+    Frame *frame = (Frame *)(gen_like->gi_frame);
+    if (!frame) {
+        return FRAME_CLEARED;
+    }
+    return frame->f_executing ? FRAME_EXECUTING : FRAME_CREATED;
+}
+
+static void set_frame_state(PyGenObject *gen_like, int fs) {
+    Frame *frame = get_frame(gen_like);
+    frame->f_executing = (fs == FRAME_EXECUTING);
+}
+
+static int valid_frame_state(int fs) {
+    return fs == FRAME_CREATED || fs == FRAME_EXECUTING || fs == FRAME_CLEARED;
+}
+
+static int get_frame_stacktop_limit(Frame *frame) {
+    PyCodeObject *code = get_frame_code(frame);
+    return code->co_stacksize + code->co_nlocals;
+}
+
+static int get_frame_stacktop(Frame *frame) {
+    assert(frame->f_localsplus);
+    int stacktop = (int)(frame->f_stacktop - frame->f_localsplus);
+    assert(stacktop >= 0 && stacktop < get_frame_stacktop_limit(frame));
+    return stacktop;
+}
+
+static void set_frame_stacktop(Frame *frame, int stacktop) {
+    assert(stacktop >= 0 && stacktop < get_frame_stacktop_limit(frame));
+    assert(frame->f_localsplus);
+    frame->f_stacktop = frame->f_localsplus + stacktop;
+}
+
+static PyObject **get_frame_localsplus(Frame *frame) {
+    PyObject **localsplus = frame->f_localsplus;
+    assert(localsplus);
+    return localsplus;
+}
+
+static int get_frame_iblock_limit(Frame *frame) {
+    return CO_MAXBLOCKS;
+}
+
+static int get_frame_iblock(Frame *frame) {
+    return frame->f_iblock;
+}
+
+static void set_frame_iblock(Frame *frame, int iblock) {
+    assert(iblock >= 0 && iblock < get_frame_iblock_limit(frame));
+    frame->f_iblock = iblock;
+}
+
+static PyTryBlock *get_frame_blockstack(Frame *frame) {
+    PyTryBlock *blockstack = frame->f_blockstack;
+    assert(blockstack);
+    return blockstack;
+}
+

src/dispatch/experimental/durable/function.py

@@ -9,7 +9,18 @@
     MethodType,
     TracebackType,
 )
-from typing import Any, Callable, Coroutine, Generator, Optional, TypeVar, Union, cast
+from typing import (
+    Any,
+    Callable,
+    Coroutine,
+    Dict,
+    Generator,
+    Optional,
+    Tuple,
+    TypeVar,
+    Union,
+    cast,
+)
 
 from . import frame as ext
 from .registry import RegisteredFunction, lookup_function, register_function
@@ -78,8 +89,8 @@ class Serializable:
     g: Union[GeneratorType, CoroutineType]
     registered_fn: RegisteredFunction
     wrapped_coroutine: Union["DurableCoroutine", None]
-    args: tuple[Any, ...]
-    kwargs: dict[str, Any]
+    args: Tuple[Any, ...]
+    kwargs: Dict[str, Any]
 
     def __init__(
         self,
@@ -274,7 +285,7 @@ def cr_await(self) -> Any:
         return self.coroutine.cr_await
 
     @property
-    def cr_origin(self) -> Optional[tuple[tuple[str, int, str], ...]]:
+    def cr_origin(self) -> Optional[Tuple[Tuple[str, int, str], ...]]:
         return self.coroutine.cr_origin
 
     def __repr__(self) -> str:

src/dispatch/experimental/durable/registry.py

@@ -1,6 +1,7 @@
 import hashlib
 from dataclasses import dataclass
 from types import FunctionType
+from typing import Dict
 
 
 @dataclass
@@ -46,7 +47,7 @@ def __setstate__(self, state):
         self.hash = code_hash
 
 
-_REGISTRY: dict[str, RegisteredFunction] = {}
+_REGISTRY: Dict[str, RegisteredFunction] = {}
 
 
 def register_function(fn: FunctionType) -> RegisteredFunction:

src/dispatch/function.py

@@ -12,6 +12,7 @@
     Dict,
     Generic,
     Iterable,
+    List,
     Optional,
     TypeVar,
     overload,
@@ -329,7 +330,7 @@ def batch(self) -> Batch:
         a set of calls to dispatch."""
         return Batch(self)
 
-    def dispatch(self, calls: Iterable[Call]) -> list[DispatchID]:
+    def dispatch(self, calls: Iterable[Call]) -> List[DispatchID]:
         """Dispatch function calls.
 
         Args:
@@ -369,7 +370,7 @@ class Batch:
 
     def __init__(self, client: Client):
         self.client = client
-        self.calls: list[Call] = []
+        self.calls: List[Call] = []
 
     def add(self, func: Function[P, T], *args: P.args, **kwargs: P.kwargs) -> Batch:
         """Add a call to the specified function to the batch."""
@@ -380,7 +381,7 @@ def add_call(self, call: Call) -> Batch:
         self.calls.append(call)
         return self
 
-    def dispatch(self) -> list[DispatchID]:
+    def dispatch(self) -> List[DispatchID]:
         """Dispatch dispatches the calls asynchronously.
 
         The batch is reset when the calls are dispatched successfully.