Source code for azure.core.polling._poller

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import base64
import logging
import threading
import uuid
try:
    from urlparse import urlparse # type: ignore # pylint: disable=unused-import
except ImportError:
    from urllib.parse import urlparse

from typing import TYPE_CHECKING, TypeVar, Generic
from azure.core.exceptions import AzureError
from azure.core.tracing.decorator import distributed_trace
from azure.core.tracing.common import with_current_context

if TYPE_CHECKING:
    from typing import Any, Callable, Union, List, Optional, Tuple


PollingReturnType = TypeVar("PollingReturnType")

_LOGGER = logging.getLogger(__name__)


[docs]class PollingMethod(Generic[PollingReturnType]): """ABC class for polling method. """
[docs] def initialize(self, client, initial_response, deserialization_callback): # type: (Any, Any, Any) -> None raise NotImplementedError("This method needs to be implemented")
[docs] def run(self): # type: () -> None raise NotImplementedError("This method needs to be implemented")
[docs] def status(self): # type: () -> str raise NotImplementedError("This method needs to be implemented")
[docs] def finished(self): # type: () -> bool raise NotImplementedError("This method needs to be implemented")
[docs] def resource(self): # type: () -> PollingReturnType raise NotImplementedError("This method needs to be implemented")
[docs] def get_continuation_token(self): # type() -> str raise TypeError( "Polling method '{}' doesn't support get_continuation_token".format( self.__class__.__name__ ) )
[docs] @classmethod def from_continuation_token(cls, continuation_token, **kwargs): # type(str, Any) -> Tuple[Any, Any, Callable] raise TypeError( "Polling method '{}' doesn't support from_continuation_token".format( cls.__name__ ) )
[docs]class NoPolling(PollingMethod): """An empty poller that returns the deserialized initial response. """ def __init__(self): self._initial_response = None self._deserialization_callback = None
[docs] def initialize(self, _, initial_response, deserialization_callback): # type: (Any, Any, Callable) -> None self._initial_response = initial_response self._deserialization_callback = deserialization_callback
[docs] def run(self): # type: () -> None """Empty run, no polling. """
[docs] def status(self): # type: () -> str """Return the current status as a string. :rtype: str """ return "succeeded"
[docs] def finished(self): # type: () -> bool """Is this polling finished? :rtype: bool """ return True
[docs] def resource(self): # type: () -> Any return self._deserialization_callback(self._initial_response)
[docs] def get_continuation_token(self): # type() -> str import pickle return base64.b64encode(pickle.dumps(self._initial_response)).decode('ascii')
[docs] @classmethod def from_continuation_token(cls, continuation_token, **kwargs): # type(str, Any) -> Tuple try: deserialization_callback = kwargs["deserialization_callback"] except KeyError: raise ValueError("Need kwarg 'deserialization_callback' to be recreated from continuation_token") import pickle initial_response = pickle.loads(base64.b64decode(continuation_token)) # nosec return None, initial_response, deserialization_callback
[docs]class LROPoller(Generic[PollingReturnType]): """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, initial_response, deserialization_callback, polling_method): # type: (Any, Any, Callable, PollingMethod[PollingReturnType]) -> None self._callbacks = [] # type: 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 = None self._exception = None if not self._polling_method.finished(): self._done = threading.Event() 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. :param callable update_cmd: The API request to check the status of the operation. """ 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, []
[docs] def polling_method(self): # type: () -> PollingMethod[PollingReturnType] """Return the polling method associated to this poller. """ return self._polling_method
[docs] def continuation_token(self): # type: () -> 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()
[docs] @classmethod def from_continuation_token(cls, polling_method, continuation_token, **kwargs): # type: (PollingMethod[PollingReturnType], str, Any) -> LROPoller[PollingReturnType] client, initial_response, deserialization_callback = polling_method.from_continuation_token( continuation_token, **kwargs ) return cls(client, initial_response, deserialization_callback, polling_method)
[docs] def status(self): # type: () -> str """Returns the current status string. :returns: The current status string :rtype: str """ return self._polling_method.status()
[docs] def result(self, timeout=None): # type: (Optional[int]) -> PollingReturnType """Return the result of the long running operation, or the result available after the specified timeout. :returns: The deserialized resource of the long running operation, if one is available. :raises ~azure.core.exceptions.HttpResponseError: Server problem with the query. """ self.wait(timeout) return self._polling_method.resource()
[docs] @distributed_trace def wait(self, timeout=None): # type: (Optional[float]) -> 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
[docs] def done(self): # type: () -> 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()
[docs] def add_done_callback(self, func): # type: (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 None or 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)
[docs] def remove_done_callback(self, func): # type: (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]