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import base64
import logging
import threading
import uuid
from typing import TypeVar, Generic, Any, Callable, Optional, Tuple, List
from azure.core.exceptions import AzureError
from azure.core.tracing.decorator import distributed_trace
from azure.core.tracing.common import with_current_context
PollingReturnType_co = TypeVar("PollingReturnType_co", covariant=True)
DeserializationCallbackType = Any
_LOGGER = logging.getLogger(__name__)
class PollingMethod(Generic[PollingReturnType_co]):
"""ABC class for polling method."""
def initialize(
self, client: Any, initial_response: Any, deserialization_callback: DeserializationCallbackType
) -> None:
raise NotImplementedError("This method needs to be implemented")
def run(self) -> None:
raise NotImplementedError("This method needs to be implemented")
def status(self) -> str:
raise NotImplementedError("This method needs to be implemented")
def finished(self) -> bool:
raise NotImplementedError("This method needs to be implemented")
def resource(self) -> PollingReturnType_co:
raise NotImplementedError("This method needs to be implemented")
def get_continuation_token(self) -> str:
raise TypeError("Polling method '{}' doesn't support get_continuation_token".format(self.__class__.__name__))
@classmethod
def from_continuation_token(
cls, continuation_token: str, **kwargs: Any
) -> Tuple[Any, Any, DeserializationCallbackType]:
raise TypeError("Polling method '{}' doesn't support from_continuation_token".format(cls.__name__))
class _SansIONoPolling(Generic[PollingReturnType_co]):
_deserialization_callback: Callable[[Any], PollingReturnType_co]
"""Deserialization callback passed during initialization"""
def __init__(self):
self._initial_response = None
def initialize(
self,
_: Any,
initial_response: Any,
deserialization_callback: Callable[[Any], PollingReturnType_co],
) -> None:
self._initial_response = initial_response
self._deserialization_callback = deserialization_callback
def status(self) -> str:
"""Return the current status.
:rtype: str
:return: The current status
"""
return "succeeded"
def finished(self) -> bool:
"""Is this polling finished?
:rtype: bool
:return: Whether this polling is finished
"""
return True
def resource(self) -> PollingReturnType_co:
return self._deserialization_callback(self._initial_response)
def get_continuation_token(self) -> str:
import pickle
return base64.b64encode(pickle.dumps(self._initial_response)).decode("ascii")
@classmethod
def from_continuation_token(
cls, continuation_token: str, **kwargs: Any
) -> Tuple[Any, Any, Callable[[Any], PollingReturnType_co]]:
try:
deserialization_callback = kwargs["deserialization_callback"]
except KeyError:
raise ValueError("Need kwarg 'deserialization_callback' to be recreated from continuation_token") from None
import pickle
initial_response = pickle.loads(base64.b64decode(continuation_token)) # nosec
return None, initial_response, deserialization_callback
class NoPolling(_SansIONoPolling[PollingReturnType_co], PollingMethod[PollingReturnType_co]):
"""An empty poller that returns the deserialized initial response."""
def run(self) -> None:
"""Empty run, no polling."""
class LROPoller(Generic[PollingReturnType_co]):
"""Poller for long running operations.
:param client: A pipeline service client
:type client: ~azure.core.PipelineClient
:param initial_response: The initial call response
:type initial_response: ~azure.core.pipeline.PipelineResponse
:param deserialization_callback: A callback that takes a Response and return a deserialized object.
If a subclass of Model is given, this passes "deserialize" as callback.
:type deserialization_callback: callable or msrest.serialization.Model
:param polling_method: The polling strategy to adopt
:type polling_method: ~azure.core.polling.PollingMethod
"""
def __init__(
self,
client: Any,
initial_response: Any,
deserialization_callback: Callable[[Any], PollingReturnType_co],
polling_method: PollingMethod[PollingReturnType_co],
) -> None:
self._callbacks: List[Callable] = []
self._polling_method = polling_method
# This implicit test avoids bringing in an explicit dependency on Model directly
try:
deserialization_callback = deserialization_callback.deserialize # type: ignore
except AttributeError:
pass
# Might raise a CloudError
self._polling_method.initialize(client, initial_response, deserialization_callback)
# Prepare thread execution
self._thread = None
self._done = threading.Event()
self._exception = None
if self._polling_method.finished():
self._done.set()
else:
self._thread = threading.Thread(
target=with_current_context(self._start),
name="LROPoller({})".format(uuid.uuid4()),
)
self._thread.daemon = True
self._thread.start()
def _start(self):
"""Start the long running operation.
On completion, runs any callbacks.
"""
try:
self._polling_method.run()
except AzureError as error:
if not error.continuation_token:
try:
error.continuation_token = self.continuation_token()
except Exception as err: # pylint: disable=broad-except
_LOGGER.warning("Unable to retrieve continuation token: %s", err)
error.continuation_token = None
self._exception = error
except Exception as error: # pylint: disable=broad-except
self._exception = error
finally:
self._done.set()
callbacks, self._callbacks = self._callbacks, []
while callbacks:
for call in callbacks:
call(self._polling_method)
callbacks, self._callbacks = self._callbacks, []
def polling_method(self) -> PollingMethod[PollingReturnType_co]:
"""Return the polling method associated to this poller.
:return: The polling method
:rtype: ~azure.core.polling.PollingMethod
"""
return self._polling_method
def continuation_token(self) -> str:
"""Return a continuation token that allows to restart the poller later.
:returns: An opaque continuation token
:rtype: str
"""
return self._polling_method.get_continuation_token()
@classmethod
def from_continuation_token(
cls, polling_method: PollingMethod[PollingReturnType_co], continuation_token: str, **kwargs: Any
) -> "LROPoller[PollingReturnType_co]":
(
client,
initial_response,
deserialization_callback,
) = polling_method.from_continuation_token(continuation_token, **kwargs)
return cls(client, initial_response, deserialization_callback, polling_method)
def status(self) -> str:
"""Returns the current status string.
:returns: The current status string
:rtype: str
"""
return self._polling_method.status()
def result(self, timeout: Optional[float] = None) -> PollingReturnType_co:
"""Return the result of the long running operation, or
the result available after the specified timeout.
:param float timeout: Period of time to wait before getting back control.
:returns: The deserialized resource of the long running operation, if one is available.
:rtype: any or None
:raises ~azure.core.exceptions.HttpResponseError: Server problem with the query.
"""
self.wait(timeout)
return self._polling_method.resource()
@distributed_trace
def wait(self, timeout: Optional[float] = None) -> None:
"""Wait on the long running operation for a specified length
of time. You can check if this call as ended with timeout with the
"done()" method.
:param float timeout: Period of time to wait for the long running
operation to complete (in seconds).
:raises ~azure.core.exceptions.HttpResponseError: Server problem with the query.
"""
if self._thread is None:
return
self._thread.join(timeout=timeout)
try:
# Let's handle possible None in forgiveness here
# https://github.com/python/mypy/issues/8165
raise self._exception # type: ignore
except TypeError: # Was None
pass
def done(self) -> bool:
"""Check status of the long running operation.
:returns: 'True' if the process has completed, else 'False'.
:rtype: bool
"""
return self._thread is None or not self._thread.is_alive()
def add_done_callback(self, func: Callable) -> None:
"""Add callback function to be run once the long running operation
has completed - regardless of the status of the operation.
:param callable func: Callback function that takes at least one
argument, a completed LongRunningOperation.
"""
# Still use "_done" and not "done", since CBs are executed inside the thread.
if self._done.is_set():
func(self._polling_method)
# Let's add them still, for consistency (if you wish to access to it for some reasons)
self._callbacks.append(func)
def remove_done_callback(self, func: Callable) -> None:
"""Remove a callback from the long running operation.
:param callable func: The function to be removed from the callbacks.
:raises ValueError: if the long running operation has already completed.
"""
if self._done is None or self._done.is_set():
raise ValueError("Process is complete.")
self._callbacks = [c for c in self._callbacks if c != func]