Issue #28544: Implement asyncio.Task in C.

This implementation provides additional 10-20% speed boost for
asyncio programs.

The patch also fixes _asynciomodule.c to use Arguments Clinic, and
makes '_schedule_callbacks' an overridable method (as it was in 3.5).

1 files changed, 76 insertions, 0 deletions

diff --git a/Lib/asyncio/base_tasks.py b/Lib/asyncio/base_tasks.py
new file mode 100644
index 0000000..5f34434
--- /dev/null
+++ b/Lib/asyncio/base_tasks.py
@@ -0,0 +1,76 @@
+import linecache
+import traceback
+
+from . import base_futures
+from . import coroutines
+
+
+def _task_repr_info(task):
+    info = base_futures._future_repr_info(task)
+
+    if task._must_cancel:
+        # replace status
+        info[0] = 'cancelling'
+
+    coro = coroutines._format_coroutine(task._coro)
+    info.insert(1, 'coro=<%s>' % coro)
+
+    if task._fut_waiter is not None:
+        info.insert(2, 'wait_for=%r' % task._fut_waiter)
+    return info
+
+
+def _task_get_stack(task, limit):
+    frames = []
+    try:
+        # 'async def' coroutines
+        f = task._coro.cr_frame
+    except AttributeError:
+        f = task._coro.gi_frame
+    if f is not None:
+        while f is not None:
+            if limit is not None:
+                if limit <= 0:
+                    break
+                limit -= 1
+            frames.append(f)
+            f = f.f_back
+        frames.reverse()
+    elif task._exception is not None:
+        tb = task._exception.__traceback__
+        while tb is not None:
+            if limit is not None:
+                if limit <= 0:
+                    break
+                limit -= 1
+            frames.append(tb.tb_frame)
+            tb = tb.tb_next
+    return frames
+
+
+def _task_print_stack(task, limit, file):
+    extracted_list = []
+    checked = set()
+    for f in task.get_stack(limit=limit):
+        lineno = f.f_lineno
+        co = f.f_code
+        filename = co.co_filename
+        name = co.co_name
+        if filename not in checked:
+            checked.add(filename)
+            linecache.checkcache(filename)
+        line = linecache.getline(filename, lineno, f.f_globals)
+        extracted_list.append((filename, lineno, name, line))
+    exc = task._exception
+    if not extracted_list:
+        print('No stack for %r' % task, file=file)
+    elif exc is not None:
+        print('Traceback for %r (most recent call last):' % task,
+              file=file)
+    else:
+        print('Stack for %r (most recent call last):' % task,
+              file=file)
+    traceback.print_list(extracted_list, file=file)
+    if exc is not None:
+        for line in traceback.format_exception_only(exc.__class__, exc):
+            print(line, file=file, end='')