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"""
bjson/request.py
Asynchronous Bidirectional JSON-RPC protocol implementation over TCP/IP
Copyright (c) 2010 David Martinez Marti
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of copyright holders nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
"""
try:
from Queue import Queue
except ImportError:
from queue import Queue
import logging
from threading import Event
import traceback
from bjsonrpc.exceptions import ServerError
import bjsonrpc.jsonlib as json
_log = logging.getLogger(__name__)
class Request(object):
"""
Represents a request to the other end which may be not be completed yet.
This class is automatically created by *method* Proxy.
Parameters:
**conn**
Connection instance which this Request belongs to.
(internally stored as Request.conn)
**request_data**
Dictionary object to serialize as JSON to send to the other end.
(internally stored as Request.data)
Attributes:
**responses**
Queue of JSON Objects of the response, each as a dictionary. If
no response has been received, this is empty.
**event_response**
A threading.Event object, which is set to true when a response has
been received. Useful to wake up threads or to wait exactly until
the response is received.
**callbacks**
List array where the developer can append functions to call when
the response is received. The function will get the Request object
as a first argument.
**request_id**
Number of ID that identifies the call. For notifications this is None.
Be careful because it may be not an integer. Strings and other objects
may be valid for other implementations.
"""
def __init__(self, conn, request_data):
self.conn = conn
self.data = request_data
self.responses = Queue()
# TODO: Now that we have a Queue, do we need an Event (and a cv)?
self.event_response = Event()
self.callbacks = []
self.thread_wait = self.event_response.wait
self.request_id = None
self.auto_close = False
if 'id' in self.data:
self.request_id = self.data['id']
if self.request_id:
self.auto_close = True
self.conn.addrequest(self)
data = json.dumps(self.data, self.conn)
self.conn.write(data)
def hasresponse(self):
"""
Method thet checks if there's a response or not.
Returns True if there it is or False if it haven't arrived yet.
"""
if not self.responses.empty(): return True
self.conn.dispatch_until_empty()
return not self.responses.empty()
def setresponse(self, value):
"""
Method used by Connection instance to tell Request that a Response
is available to this request.
Parameters:
**value**
Value (JSON decoded) received from socket.
"""
self.responses.put(value)
for callback in self.callbacks:
try:
callback(self)
except Exception as exc:
_log.error("Error on callback: %r", exc)
_log.debug(traceback.format_exc())
self.event_response.set() # helper for threads.
if self.auto_close:
self.close()
def wait(self):
"""
Block until there is a response. Will manage the socket and dispatch
messages until the response is found.
"""
#if self.response is None:
# self.conn.read_ensure_thread()
while self.responses.empty():
self.conn.read_and_dispatch(condition=lambda: self.responses.empty())
def __call__(self):
return self.value
def __iter__(self):
return self
def __next__(self):
return self.value
def next(self):
return self.__next__()
def close(self):
reqid, self.request_id, self.auto_close = self.request_id, None, False
if reqid:
self.conn.delrequest(reqid)
def __del__(self):
self.close()
@property
def value(self):
"""
Property to get value response. If the response is not available, it waits
to it (see *wait* method). If the response contains an Error, this
method raises *exceptions.ServerError* with the error text inside.
From version 0.2.0 you can also call the class itself to get the value::
req_stime = rpcconn.method.getServerTime()
print req_stime.value
print req_stime() # equivalent to the prior line.
"""
self.wait()
response = self.responses.get()
err = response.get('error', None)
if err is not None:
raise ServerError(err)
return response['result']