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import enum
import threading
import uuid
from typing import List, Dict, Any, Optional, Callable
from .DBusInterface import DBusInterface
## Wrapper around the Charon DBus service that hides the DBus details.
#
# This class encapsulates all the data and information needed for
# retrieving some data from a file supported by the Charon file service.
#
# It can be used to simplify dealing with the DBus service.
class Request:
# The request state.
class State(enum.IntEnum):
Initial = 0 # Request was created, but not started yet.
Running = 1 # Request was started.
Completed = 2 # Request completed successfully.
Error = 3 # Request encountered an error.
## Constructor.
#
# \param file_path The path to a file to get data from.
# \param virtual_paths A list of virtual paths with the data to retrieve.
def __init__(self, file_path: str, virtual_paths: List[str]) -> None:
self.__file_path = file_path
self.__virtual_paths = virtual_paths
self.__state = self.State.Initial
self.__request_id = 0
self.__data = {} # type: Dict[str, Any]
self.__error_string = ""
self.__event = threading.Event()
self.__request_data_callback = None # type: Optional[Callable[["Request", Dict[str, Any]], None]]
self.__request_completed_callback = None # type: Optional[Callable[["Request"], None]]
self.__request_error_callback = None # type: Optional[Callable[["Request", str], None]]
## Cleanup function.
def __del__(self):
if self.__state != self.State.Initial:
self.stop()
DBusInterface.disconnectSignal("requestData", self.__onRequestData)
DBusInterface.disconnectSignal("requestCompleted", self.__onRequestCompleted)
DBusInterface.disconnectSignal("requestError", self.__onRequestError)
## The file path for this request.
@property
def filePath(self) -> str:
return self.__file_path
## The virtual paths for this request.
@property
def virtualPaths(self) -> List[str]:
return self.__virtual_paths
## The state of this request.
@property
def state(self) -> State:
return self.__state
## The data associated with this request.
#
# Note that this will be an empty dictionary until the request
# completed.
@property
def data(self) -> Dict[str, Any]:
return self.__data
## A description of the error that was encountered during the request.
#
# Note that this will be an empty string if there was no error.
@property
def errorString(self) -> str:
return self.__error_string
## Set the callbacks that should be called while the request is running.
#
# Note: These parameters can only be passed as keyword arguments.
# \param data The callback to call when data is received. Will be passed the request object and a dict with data.
# \param completed The callback to call when the request has completed. Will be passed the request object.
# \param error The callback to call when the request encountered an error. Will be passed the request object and a string describing the error.
#
def setCallbacks(self, *,
data: Callable[["Request", Dict[str, Any]], None] = None,
completed: Callable[["Request"], None] = None,
error: Callable[["Request", str], None] = None) -> None:
self.__request_data_callback = data
self.__request_completed_callback = completed
self.__request_error_callback = error
## Start the request.
def start(self):
if self.__state != self.State.Initial:
return
self.__request_id = str(uuid.uuid4())
DBusInterface.connectSignal("requestData", self.__onRequestData)
DBusInterface.connectSignal("requestCompleted", self.__onRequestCompleted)
DBusInterface.connectSignal("requestError", self.__onRequestError)
self.__state = self.State.Running
DBusInterface.callAsync("startRequest", self.__startSuccess, self.__startError, "ssas", self.__request_id, self.__file_path, self.__virtual_paths)
## Stop the request.
#
# Note that this may fail if the file service was already processing the request.
def stop(self):
if self.__state != self.State.Running:
return
DBusInterface.callAsync("cancelRequest", None, None, "s", self.__request_id)
## Wait until the request is finished.
#
# Warning! This method will block the calling thread until it is finished. The DBus implementations
# require a running event loop for signal delivery to work. This means that if you block the main
# loop with this method, you will deadlock since the completed signal is never received.
def waitForFinished(self):
if self.__state == self.State.Initial:
self.start()
self.__event.clear()
self.__event.wait()
def __startSuccess(self, start_success: bool):
if not start_success:
self.__startError("Could not start the request")
return
def __startError(self, error: str):
self.__state = self.State.Error
self.__error_string = error
self.__event.set()
if self.__request_error_callback:
self.__request_error_callback(self, error)
def __onRequestData(self, request_id: str, data: Dict[str, Any]):
if self.__state != self.State.Running:
return
if self.__request_id != request_id:
return
self.__data.update(data)
if self.__request_data_callback:
self.__request_data_callback(self, data)
def __onRequestCompleted(self, request_id: str):
if self.__state != self.State.Running:
return
if self.__request_id != request_id:
return
self.__state = self.State.Completed
if self.__request_completed_callback:
self.__request_completed_callback(self)
self.__event.set()
def __onRequestError(self, request_id: str, error_string: str):
if self.__request_id != request_id:
return
self.__state = self.State.Error
self.__error_string = error_string
if self.__request_error_callback:
self.__request_error_callback(self, error_string)
self.__event.set()
def __repr__(self):
return "<Charon.Client.Request ({id}) file_path = {path} virtual_paths = {virtual} >".format(id = id(self), path = self.__file_path, virtual = self.__virtual_paths)
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