Files
ray-project--ray/python/ray/serve/_private/utils.py
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2026-07-13 13:17:40 +08:00

893 lines
28 KiB
Python

import asyncio
import collections
import copy
import errno
import importlib
import inspect
import logging
import random
import re
import time
import uuid
import zlib
from decimal import ROUND_HALF_UP, Decimal
from enum import Enum
from functools import wraps
from typing import Any, Callable, Dict, List, Optional, Set, TypeVar, Union
import requests
import ray
import ray.util.serialization_addons
from ray import cloudpickle
from ray._common.constants import HEAD_NODE_RESOURCE_NAME
from ray._common.utils import get_random_alphanumeric_string, import_attr
from ray._raylet import MessagePackSerializer
from ray.actor import ActorHandle
from ray.serve._private.common import DeploymentID, RequestMetadata, ServeComponentType
from ray.serve._private.constants import (
HTTP_PROXY_TIMEOUT,
SERVE_DEPLOYMENT_ACTOR_PREFIX,
SERVE_LOGGER_NAME,
SERVE_NAMESPACE,
)
from ray.types import ObjectRef
from ray.util.serialization import StandaloneSerializationContext
try:
import pandas as pd
except ImportError:
pd = None
try:
import numpy as np
except ImportError:
np = None
FILE_NAME_REGEX = r"[^\x20-\x7E]|[<>:\"/\\|?*]"
MESSAGE_PACK_OFFSET = 9
# Attribute set on functions/methods decorated with `@serve.multiplexed`. The
# `__serve_multiplex_wrapper` is only created lazily on the first call, so this
# marker is used to detect multiplexing statically (e.g. at replica startup)
# without invoking user code.
MULTIPLEXED_FUNCTION_MARKER_ATTR = "_serve_multiplexed_function"
def _callable_uses_multiplexing(callable_obj: Any) -> bool:
"""Whether `callable_obj` is or defines an `@serve.multiplexed` function.
Accepts a standalone function, a class, or a class instance, so it can be used
both at build time (where the deployment's `func_or_class` is available) and at
runtime (where an initialized instance is available).
For an instance it also inspects instance attributes, so multiplexing that is
wired up dynamically at init time (e.g. ``self._load_model =
serve.multiplexed(...)(fn)``) is detected. This case can only be caught at
runtime, since it is not visible on the class statically.
"""
# NOTE: the marker is checked with `is True` rather than truthiness because some
# objects (e.g. `DeploymentHandle`, whose `__getattr__` returns a handle for any
# name) return a truthy value for an arbitrary attribute. The decorator always
# sets the marker to the literal `True`, so this stays exact without false
# positives.
def _has_marker(obj: Any) -> bool:
return getattr(obj, MULTIPLEXED_FUNCTION_MARKER_ATTR, False) is True
# Standalone function deployment decorated with `@serve.multiplexed`.
if _has_marker(callable_obj):
return True
# A class (or instance of one) with a method decorated with `@serve.multiplexed`.
klass = callable_obj if isinstance(callable_obj, type) else type(callable_obj)
for base in klass.__mro__:
for attr in base.__dict__.values():
if _has_marker(attr):
return True
# An instance that stored a multiplexed wrapper as an instance attribute.
if not isinstance(callable_obj, type):
for attr in getattr(callable_obj, "__dict__", {}).values():
if _has_marker(attr):
return True
return False
def asyncio_grpc_exception_handler(loop, context):
"""Exception handler to filter out false positive BlockingIOErrors from gRPC."""
exc = context.get("exception")
msg = context.get("message")
if (
exc
and isinstance(exc, BlockingIOError)
and exc.errno == errno.EAGAIN
and "PollerCompletionQueue._handle_events" in msg
):
return
loop.default_exception_handler(context)
def validate_ssl_config(
ssl_certfile: Optional[str], ssl_keyfile: Optional[str]
) -> None:
"""Validate SSL configuration for HTTPS support.
Args:
ssl_certfile: Path to SSL certificate file
ssl_keyfile: Path to SSL private key file
Raises:
ValueError: If only one of ssl_certfile or ssl_keyfile is provided
"""
if (ssl_certfile and not ssl_keyfile) or (ssl_keyfile and not ssl_certfile):
raise ValueError(
"Both ssl_keyfile and ssl_certfile must be provided together "
"to enable HTTPS."
)
def get_deployment_actor_name(
deployment_id: DeploymentID,
actor_name: str,
code_version: str,
) -> str:
"""Return the deterministic Ray actor name for a deployment-scoped actor.
The name is versioned by code_version to allow old and new replicas to
coexist during rollout (each uses its version's actors). Actors serve as
central state for replicas, so we version by code_version to ensure fresh
actors when a new code version is deployed.
"""
base = (
f"{SERVE_DEPLOYMENT_ACTOR_PREFIX}{deployment_id.app_name}"
f"::{deployment_id.name}"
)
return f"{base}::{code_version}::{actor_name}"
GENERATOR_COMPOSITION_NOT_SUPPORTED_ERROR = RuntimeError(
"Streaming deployment handle results cannot be passed to "
"downstream handle calls. If you have a use case requiring "
"this feature, please file a feature request on GitHub."
)
# Use a global singleton enum to emulate default options. We cannot use None
# for those option because None is a valid new value.
class DEFAULT(Enum):
VALUE = 1
class DeploymentOptionUpdateType(str, Enum):
# Nothing needs to be done other than setting the target state.
LightWeight = "LightWeight"
# Each DeploymentReplica instance (tracked in DeploymentState) uses certain options
# from the deployment config. These values need to be updated in DeploymentReplica.
NeedsReconfigure = "NeedsReconfigure"
# Options that are sent to the replica actor. If changed, reconfigure() on the actor
# needs to be called to update these values.
NeedsActorReconfigure = "NeedsActorReconfigure"
# If changed, restart all replicas.
HeavyWeight = "HeavyWeight"
# Type alias: objects that can be DEFAULT.VALUE have type Default[T]
T = TypeVar("T")
Default = Union[DEFAULT, T]
logger = logging.getLogger(SERVE_LOGGER_NAME)
# Format for component files
FILE_FMT = "{component_name}_{component_id}{suffix}"
class _ServeCustomEncoders:
"""Group of custom encoders for common types that's not handled by FastAPI."""
@staticmethod
def encode_np_array(obj):
assert isinstance(obj, np.ndarray)
if obj.dtype.kind == "f": # floats
obj = obj.astype(float)
if obj.dtype.kind in {"i", "u"}: # signed and unsigned integers.
obj = obj.astype(int)
return obj.tolist()
@staticmethod
def encode_np_scaler(obj):
assert isinstance(obj, np.generic)
return obj.item()
@staticmethod
def encode_exception(obj):
assert isinstance(obj, Exception)
return str(obj)
@staticmethod
def encode_pandas_dataframe(obj):
assert isinstance(obj, pd.DataFrame)
return obj.to_dict(orient="records")
serve_encoders = {Exception: _ServeCustomEncoders.encode_exception}
if np is not None:
serve_encoders[np.ndarray] = _ServeCustomEncoders.encode_np_array
serve_encoders[np.generic] = _ServeCustomEncoders.encode_np_scaler
if pd is not None:
serve_encoders[pd.DataFrame] = _ServeCustomEncoders.encode_pandas_dataframe
@ray.remote(num_cpus=0)
def block_until_http_ready(
http_endpoint,
backoff_time_s=1,
check_ready=None,
timeout=HTTP_PROXY_TIMEOUT,
):
http_is_ready = False
start_time = time.time()
while not http_is_ready:
try:
resp = requests.get(http_endpoint)
assert resp.status_code == 200
if check_ready is None:
http_is_ready = True
else:
http_is_ready = check_ready(resp)
except Exception:
pass
if 0 < timeout < time.time() - start_time:
raise TimeoutError("HTTP proxy not ready after {} seconds.".format(timeout))
time.sleep(backoff_time_s)
def get_random_string(length: int = 8):
return get_random_alphanumeric_string(length)
def format_actor_name(actor_name, *modifiers):
name = actor_name
for modifier in modifiers:
name += "-{}".format(modifier)
return name
CLASS_WRAPPER_METADATA_ATTRS = (
"__name__",
"__qualname__",
"__module__",
"__doc__",
"__annotations__",
)
def copy_class_metadata(wrapper_cls, target_cls) -> None:
"""Copy common class-level metadata onto a wrapper class."""
for attr in CLASS_WRAPPER_METADATA_ATTRS:
if attr == "__annotations__":
target_annotations = getattr(target_cls, "__annotations__", None)
if target_annotations:
merged_annotations = dict(
wrapper_cls.__dict__.get("__annotations__", {})
)
for key, value in target_annotations.items():
merged_annotations.setdefault(key, value)
wrapper_cls.__annotations__ = merged_annotations
continue
if hasattr(target_cls, attr):
setattr(wrapper_cls, attr, getattr(target_cls, attr))
wrapper_cls.__wrapped__ = target_cls
def ensure_serialization_context():
"""Ensure the serialization addons on registered, even when Ray has not
been started."""
ctx = StandaloneSerializationContext()
ray.util.serialization_addons.apply(ctx)
def msgpack_serialize(obj):
ctx = ray._private.worker.global_worker.get_serialization_context()
buffer = ctx.serialize(obj)
serialized = buffer.to_bytes()
return serialized
def msgpack_deserialize(data):
# todo: Ray does not provide a msgpack deserialization api.
try:
obj = MessagePackSerializer.loads(data[MESSAGE_PACK_OFFSET:], None)
except Exception:
raise
return obj
def merge_dict(dict1, dict2):
if dict1 is None and dict2 is None:
return None
if dict1 is None:
dict1 = dict()
if dict2 is None:
dict2 = dict()
result = dict()
for key in dict1.keys() | dict2.keys():
result[key] = sum([e.get(key, 0) for e in (dict1, dict2)])
return result
def parse_import_path(import_path: str):
"""
Takes in an import_path of form:
[subdirectory 1].[subdir 2]...[subdir n].[file name].[attribute name]
Parses this path and returns the module name (everything before the last
dot) and attribute name (everything after the last dot), such that the
attribute can be imported using "from module_name import attr_name".
"""
nodes = import_path.split(".")
if len(nodes) < 2:
raise ValueError(
f"Got {import_path} as import path. The import path "
f"should at least specify the file name and "
f"attribute name connected by a dot."
)
return ".".join(nodes[:-1]), nodes[-1]
def override_runtime_envs_except_env_vars(parent_env: Dict, child_env: Dict) -> Dict:
"""Creates a runtime_env dict by merging a parent and child environment.
This method is not destructive. It leaves the parent and child envs
the same.
The merge is a shallow update where the child environment inherits the
parent environment's settings. If the child environment specifies any
env settings, those settings take precdence over the parent.
- Note: env_vars are a special case. The child's env_vars are combined
with the parent.
Args:
parent_env: The environment to inherit settings from.
child_env: The environment with override settings.
Returns:
A new dictionary containing the merged runtime_env settings.
Raises:
TypeError: If a dictionary is not passed in for parent_env or child_env.
"""
if not isinstance(parent_env, Dict):
raise TypeError(
f'Got unexpected type "{type(parent_env)}" for parent_env. '
"parent_env must be a dictionary."
)
if not isinstance(child_env, Dict):
raise TypeError(
f'Got unexpected type "{type(child_env)}" for child_env. '
"child_env must be a dictionary."
)
defaults = copy.deepcopy(parent_env)
overrides = copy.deepcopy(child_env)
default_env_vars = defaults.get("env_vars", {})
override_env_vars = overrides.get("env_vars", {})
defaults.update(overrides)
default_env_vars.update(override_env_vars)
defaults["env_vars"] = default_env_vars
return defaults
class JavaActorHandleProxy:
"""Wraps actor handle and translate snake_case to camelCase."""
def __init__(self, handle: ActorHandle):
self.handle = handle
self._available_attrs = set(dir(self.handle))
def __getattr__(self, key: str):
if key in self._available_attrs:
camel_case_key = key
else:
components = key.split("_")
camel_case_key = components[0] + "".join(x.title() for x in components[1:])
return getattr(self.handle, camel_case_key)
def require_packages(packages: List[str]):
"""Decorator making sure function run in specified environments
Examples:
>>> from ray.serve._private.utils import require_packages
>>> @require_packages(["numpy", "package_a"]) # doctest: +SKIP
... def func(): # doctest: +SKIP
... import numpy as np # doctest: +SKIP
... ... # doctest: +SKIP
>>> func() # doctest: +SKIP
ImportError: func requires ["numpy", "package_a"] but
["package_a"] are not available, please pip install them.
Args:
packages: The list of package names that must be importable when the
decorated function is invoked.
Returns:
A decorator that wraps the target function with the package check.
"""
def decorator(func):
def check_import_once():
if not hasattr(func, "_require_packages_checked"):
missing_packages = []
for package in packages:
try:
importlib.import_module(package)
except ModuleNotFoundError:
missing_packages.append(package)
if len(missing_packages) > 0:
raise ImportError(
f"{func} requires packages {packages} to run but "
f"{missing_packages} are missing. Please "
"`pip install` them or add them to "
"`runtime_env`."
)
func._require_packages_checked = True
if inspect.iscoroutinefunction(func):
@wraps(func)
async def wrapped(*args, **kwargs):
check_import_once()
return await func(*args, **kwargs)
elif inspect.isroutine(func):
@wraps(func)
def wrapped(*args, **kwargs):
check_import_once()
return func(*args, **kwargs)
else:
raise ValueError("Decorator expect callable functions.")
return wrapped
return decorator
def in_interactive_shell():
# Taken from:
# https://stackoverflow.com/questions/15411967/how-can-i-check-if-code-is-executed-in-the-ipython-notebook
import __main__ as main
return not hasattr(main, "__file__")
def snake_to_camel_case(snake_str: str) -> str:
"""Convert a snake case string to camel case."""
words = snake_str.strip("_").split("_")
return words[0] + "".join(word[:1].upper() + word[1:] for word in words[1:])
def check_obj_ref_ready_nowait(obj_ref: ObjectRef) -> bool:
"""Check if ray object reference is ready without waiting for it."""
finished, _ = ray.wait([obj_ref], timeout=0)
return len(finished) == 1
def compress_metric_report(report: Any) -> bytes:
"""Compress a metric report (HandleMetricReport or ReplicaMetricReport) for RPC.
Uses zlib level 9 (stdlib, no extra deps). ~75KB uncompressed -> ~5KB for 1000 replicas.
"""
return zlib.compress(cloudpickle.dumps(report), level=9)
def decompress_metric_report(compressed: bytes) -> Any:
"""Decompress a metric report from RPC."""
return cloudpickle.loads(zlib.decompress(compressed))
def extract_self_if_method_call(args: List[Any], func: Callable) -> Optional[object]:
"""Check if this is a method rather than a function.
Does this by checking to see if `func` is the attribute of the first
(`self`) argument under `func.__name__`. Unfortunately, this is the most
robust solution to this I was able to find. It would also be preferable
to do this check when the decorator runs, rather than when the method is.
Arguments:
args: arguments to the function/method call.
func: the unbound function that was called.
Returns:
The ``self`` object if it's a method call, else ``None``.
"""
if len(args) > 0:
method = getattr(args[0], func.__name__, False)
if method:
wrapped = getattr(method, "__wrapped__", False)
if wrapped and wrapped == func:
return args[0]
return None
def call_function_from_import_path(import_path: str) -> Any:
"""Call the function given import path.
Args:
import_path: The import path of the function to call.
Raises:
ValueError: If the import path is invalid.
TypeError: If the import path is not callable.
RuntimeError: if the function raise exeception during execution.
Returns:
The result of the function call.
"""
try:
callback_func = import_attr(import_path)
except Exception as e:
raise ValueError(f"The import path {import_path} cannot be imported: {e}")
if not callable(callback_func):
raise TypeError(f"The import path {import_path} is not callable.")
try:
return callback_func()
except Exception as e:
raise RuntimeError(f"The function {import_path} raised an exception: {e}")
def get_head_node_id() -> str:
"""Get the head node id.
Iterate through all nodes in the ray cluster and return the node id of the first
alive node with head node resource.
"""
head_node_id = None
for node in ray.nodes():
if HEAD_NODE_RESOURCE_NAME in node["Resources"] and node["Alive"]:
head_node_id = node["NodeID"]
break
assert head_node_id is not None, "Cannot find alive head node."
return head_node_id
def calculate_remaining_timeout(
*,
timeout_s: Optional[float],
start_time_s: float,
curr_time_s: float,
) -> Optional[float]:
"""Get the timeout remaining given an overall timeout, start time, and curr time.
If the timeout passed in was `None` or negative, will always return that timeout
directly.
If the timeout is >= 0, the returned remaining timeout always be >= 0.
"""
if timeout_s is None or timeout_s < 0:
return timeout_s
time_since_start_s = curr_time_s - start_time_s
return max(0, timeout_s - time_since_start_s)
def get_all_live_placement_group_names() -> List[str]:
"""Fetch and parse the Ray placement group table for live placement group names.
Placement groups are filtered based on their `scheduling_state`; any placement
group not in the "REMOVED" state is considered live.
"""
placement_group_table = ray.util.placement_group_table()
live_pg_names = []
for entry in placement_group_table.values():
pg_name = entry.get("name", "")
if (
pg_name
and entry.get("stats", {}).get("scheduling_state", "UNKNOWN") != "REMOVED"
):
live_pg_names.append(pg_name)
return live_pg_names
def get_active_placement_group_ids() -> Set[str]:
"""
Retrieve the set of placement group IDs referenced by alive Serve actors.
Returns:
The set of placement group IDs referenced by alive Serve actors.
"""
# TODO (jeffreywang): Move the imports to the top of the file.
# https://github.com/ray-project/ray/issues/61330
from ray.util.state import list_actors
from ray.util.state.common import RAY_MAX_LIMIT_FROM_API_SERVER
actors = list_actors(
filters=[
("ray_namespace", "=", SERVE_NAMESPACE),
("state", "=", "ALIVE"),
],
limit=RAY_MAX_LIMIT_FROM_API_SERVER,
detail=True,
raise_on_missing_output=False,
)
return {
actor.placement_group_id
for actor in actors
if actor.placement_group_id is not None
}
def get_current_actor_id() -> str:
"""Gets the ID of the calling actor.
If this is called in a driver, returns "DRIVER."
If otherwise called outside of an actor, returns an empty string.
This function hangs when GCS is down due to the `ray.get_runtime_context()`
call.
"""
worker_mode = ray.get_runtime_context().worker.mode
if worker_mode == ray.SCRIPT_MODE:
return "DRIVER"
else:
try:
actor_id = ray.get_runtime_context().get_actor_id()
if actor_id is None:
return ""
else:
return actor_id
except Exception:
return ""
def is_running_in_asyncio_loop() -> bool:
try:
asyncio.get_running_loop()
return True
except RuntimeError:
return False
def get_capacity_adjusted_num_replicas(
num_replicas: int, target_capacity: Optional[float]
) -> int:
"""Return the `num_replicas` adjusted by the `target_capacity`.
The output will only ever be 0 if `target_capacity` is 0 or `num_replicas` is
0 (to support autoscaling deployments using scale-to-zero).
Rather than using the default `round` behavior in Python, which rounds half to
even, uses the `decimal` module to round half up (standard rounding behavior).
"""
if target_capacity is None or target_capacity == 100:
return num_replicas
if target_capacity == 0 or num_replicas == 0:
return 0
adjusted_num_replicas = Decimal(num_replicas * target_capacity) / Decimal(100.0)
rounded_adjusted_num_replicas = adjusted_num_replicas.to_integral_value(
rounding=ROUND_HALF_UP
)
return max(1, int(rounded_adjusted_num_replicas))
def generate_request_id() -> str:
# NOTE(edoakes): we use random.getrandbits because it reduces CPU overhead
# significantly. This is less cryptographically secure but should be ok for
# request ID generation.
# See https://bugs.python.org/issue45556 for discussion.
return str(uuid.UUID(int=random.getrandbits(128), version=4))
def inside_ray_client_context() -> bool:
return ray.util.client.ray.is_connected()
def get_component_file_name(
component_name: str,
component_id: str,
component_type: Optional[ServeComponentType],
suffix: str = "",
) -> str:
"""Get the component's file name. Replaces special characters with underscores."""
component_name = re.sub(FILE_NAME_REGEX, "_", component_name)
# For DEPLOYMENT component type, we want to log the deployment name
# instead of adding the component type to the component name.
component_log_file_name = component_name
if component_type is not None:
component_log_file_name = f"{component_type.value}_{component_name}"
if component_type != ServeComponentType.REPLICA:
component_name = f"{component_type}_{component_name}"
file_name = FILE_FMT.format(
component_name=component_log_file_name,
component_id=component_id,
suffix=suffix,
)
return file_name
def validate_route_prefix(route_prefix: Union[DEFAULT, None, str]):
if route_prefix is DEFAULT.VALUE or route_prefix is None:
return
if not route_prefix.startswith("/"):
raise ValueError(
f"Invalid route_prefix '{route_prefix}', "
"must start with a forward slash ('/')."
)
if route_prefix != "/" and route_prefix.endswith("/"):
raise ValueError(
f"Invalid route_prefix '{route_prefix}', "
"may not end with a trailing '/'."
)
if "{" in route_prefix or "}" in route_prefix:
raise ValueError(
f"Invalid route_prefix '{route_prefix}', may not contain wildcards."
)
async def await_deployment_response(deployment_response):
return await deployment_response
async def resolve_deployment_response(obj: Any, request_metadata: RequestMetadata):
"""Resolve `DeploymentResponse` objects to underlying object references.
This enables composition without explicitly calling `_to_object_ref`.
"""
from ray.serve.handle import DeploymentResponse, DeploymentResponseGenerator
if isinstance(obj, DeploymentResponseGenerator):
raise GENERATOR_COMPOSITION_NOT_SUPPORTED_ERROR
elif isinstance(obj, DeploymentResponse):
if request_metadata._by_reference and obj.by_reference:
# If sending requests by reference, launch async task to
# convert DeploymentResponse to an object ref
return asyncio.create_task(obj._to_object_ref())
else:
# Otherwise, resolve DeploymentResponse directly to result
return asyncio.create_task(await_deployment_response(obj))
elif not request_metadata._by_reference and isinstance(obj, ray.ObjectRef):
# If the router is sending requests by value (i.e. using gRPC),
# resolve all Ray objects to mirror Ray behavior
return asyncio.wrap_future(obj.future())
def wait_for_interrupt() -> None:
try:
while True:
# Block, letting Ray print logs to the terminal.
time.sleep(10)
except KeyboardInterrupt:
logger.warning("Got KeyboardInterrupt, exiting...")
# We need to re-raise KeyboardInterrupt, so serve components can be shutdown
# from the main script.
raise
def is_grpc_enabled(grpc_config) -> bool:
return grpc_config.port > 0 and len(grpc_config.grpc_servicer_functions) > 0
class Semaphore:
"""Based on asyncio.Semaphore.
This is a semaphore that can be used to limit the number of concurrent requests.
Its maximum value is dynamic and is determined by the `get_value_fn` function.
"""
def __init__(self, get_value_fn: Callable[[], int]):
self._waiters = None
self._value = 0
self._get_value_fn = get_value_fn
def __repr__(self):
res = super().__repr__()
extra = "locked" if self.locked() else f"unlocked, value:{self._value}"
if self._waiters:
extra = f"{extra}, waiters:{len(self._waiters)}"
return f"<{res[1:-1]} [{extra}]>"
async def __aenter__(self):
await self.acquire()
# We have no use for the "as ..." clause in the with
# statement for locks.
return None
async def __aexit__(self, exc_type, exc, tb):
self.release()
def get_max_value(self):
return self._get_value_fn()
def locked(self):
"""Returns True if semaphore cannot be acquired immediately."""
return self._value >= self.get_max_value() or (
any(not w.cancelled() for w in (self._waiters or ()))
)
async def acquire(self):
"""Acquire a semaphore.
If the internal counter is larger than zero on entry,
decrement it by one and return True immediately. If it is
zero on entry, block, waiting until some other coroutine has
called release() to make it larger than 0, and then return
True.
"""
if not self.locked():
self._value += 1
return True
if self._waiters is None:
self._waiters = collections.deque()
fut = asyncio.Future()
self._waiters.append(fut)
# Finally block should be called before the CancelledError
# handling as we don't want CancelledError to call
# _wake_up_first() and attempt to wake up itself.
try:
try:
await fut
finally:
self._waiters.remove(fut)
except asyncio.CancelledError:
if not fut.cancelled():
self._value -= 1
self._wake_up_next()
raise
if self._value < self.get_max_value():
self._wake_up_next()
return True
def release(self):
"""Release a semaphore, incrementing the internal counter by one.
When it was zero on entry and another coroutine is waiting for it to
become larger than zero again, wake up that coroutine.
"""
self._value -= 1
self._wake_up_next()
def _wake_up_next(self):
"""Wake up the first waiter that isn't done."""
if not self._waiters:
return
for fut in self._waiters:
if not fut.done():
self._value += 1
fut.set_result(True)
return