{{ message }}
-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathjsonrpc.py
More file actions
664 lines (512 loc) · 19.2 KB
/
Copy pathjsonrpc.py
File metadata and controls
664 lines (512 loc) · 19.2 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
# coding: utf-8
"""
Minimal python RPC implementation in a single file based on the JSON-RPC 2.0 specs from
http://www.jsonrpc.org/specification.
"""
__author__ = "Marcel Rieger"
__email__ = "python-jsonrpyc@googlegroups.com"
__copyright__ = "Copyright 2016-2021, Marcel Rieger"
__credits__ = ["Marcel Rieger"]
__contact__ = "https://github.com/riga/jsonrpyc"
__license__ = "BSD-3-Clause"
__status__ = "Development"
__version__ = "1.1.1"
__all__ = ["RPC"]
import io
import json
import logging
import sys
import threading
import time
from queue import Queue
class Spec(object):
"""
This class wraps methods that create JSON-RPC 2.0 compatible string representations of
request, response and error objects. All methods are class members, so you might never want to
create an instance of this class, but rather use the methods directly:
.. code-block:: python
Spec.request("my_method", 18) # the id is optional
# => '{"jsonrpc":"2.0","method":"my_method","id": 18}'
Spec.response(18, "some_result")
# => '{"jsonrpc":"2.0","id":18,"result":"some_result"}'
Spec.error(18, -32603)
# => '{"jsonrpc":"2.0","id":18,"error":{"code":-32603,"message":"Internal error"}}'
"""
@classmethod
def check_id(cls, id, allow_empty=False):
"""
Value check for *id* entries. When *allow_empty* is *True*, *id* is allowed to be *None*.
Raises a *TypeError* when *id* is neither an integer nor a string.
"""
if (id is not None or not allow_empty) and not isinstance(id, (int, str)):
raise TypeError(
"id must be an integer or string, got {} ({})".format(id, type(id))
)
@classmethod
def check_method(cls, method):
"""
Value check for *method* entries. Raises a *TypeError* when *method* is not a string.
"""
if not isinstance(method, str):
raise TypeError(
"method must be a string, got {} ({})".format(method, type(method))
)
@classmethod
def check_code(cls, code):
"""
Value check for *code* entries. Raises a *TypeError* when *code* is not an integer, or a
*KeyError* when there is no :py:class:`RPCError` subclass registered for that *code*.
"""
if not isinstance(code, int):
raise TypeError("code must be an integer, got {} ({})".format(id, type(id)))
if not get_error(code):
raise ValueError("unknown code, got {} ({})".format(code, type(code)))
@classmethod
def request(cls, method, id=None, params=None):
"""
Creates the string representation of a request that calls *method* with optional *params*
which are encoded by ``json.dumps``. When *id* is *None*, the request is considered a
notification.
"""
try:
cls.check_method(method)
cls.check_id(id, allow_empty=True)
except Exception as e:
raise RPCInvalidRequest(str(e))
# start building the request string
req = '{{"jsonrpc":"2.0","method":"{}"'.format(method)
# add the id when given
if id is not None:
# encode string ids
if isinstance(id, str):
id = json.dumps(id)
req += ',"id":{}'.format(id)
# add parameters when given
if params is not None:
try:
req += ',"params":{}'.format(json.dumps(params))
except Exception as e:
raise RPCParseError(str(e))
# end the request string
req += "}"
return req
@classmethod
def response(cls, id, result):
"""
Creates the string representation of a respone that was triggered by a request with *id*.
A *result* is required, even if it is *None*.
"""
try:
cls.check_id(id)
except Exception as e:
raise RPCInvalidRequest(str(e))
# encode string ids
if isinstance(id, str):
id = json.dumps(id)
# build the response string
try:
res = '{{"jsonrpc":"2.0","id":{},"result":{}}}'.format(
id, json.dumps(result)
)
except Exception as e:
raise RPCParseError(str(e))
return res
@classmethod
def error(cls, id, code, data=None):
"""
Creates the string representation of an error that occured while processing a request with
*id*. *code* must lead to a registered :py:class:`RPCError`. *data* might contain
additional, detailed error information and is encoded by ``json.dumps`` when set.
"""
try:
cls.check_id(id)
cls.check_code(code)
except Exception as e:
raise RPCInvalidRequest(str(e))
# build the inner error data
message = get_error(code).title
err_data = '{{"code":{},"message":"{}"'.format(code, message)
# insert data when given
if data is not None:
try:
err_data += ',"data":{}}}'.format(json.dumps(data))
except Exception as e:
raise RPCParseError(str(e))
else:
err_data += "}"
# encode string ids
if isinstance(id, str):
id = json.dumps(id)
# start building the error string
err = '{{"jsonrpc":"2.0","id":{},"error":{}}}'.format(id, err_data)
return err
class RPC(object):
"""
The main class of *jsonrpyc*. Instances of this class wrap an input stream *stdin* and an output
stream *stdout* in order to communicate with other services. A service is not even forced to be
written in Python as long as it strictly implements the JSON-RPC 2.0 specification. RPC
instances may wrap a *target* object. By means of a :py:class:`Watchdog` instance, incoming
requests are routed to methods of this object whose result might be sent back as a response.
The watchdog instance is created but not started yet, when *watch* is not *True*.
Example implementation:
*server.py*
.. code-block:: python
import jsonrpyc
class MyTarget(object):
def greet(self, name):
return f"Hi, {name}!"
jsonrpc.RPC(MyTarget())
*client.py*
.. code-block:: python
import jsonrpyc
from subprocess import Popen, PIPE
p = Popen(["python", "server.py"], stdin=PIPE, stdout=PIPE)
rpc = jsonrpyc.RPC(stdout=p.stdin, stdin=p.stdout)
# non-blocking remote procedure call with callback and js-like signature
def cb(err, res=None):
if err:
throw err
print(f"callback got: {res}")
rpc("greet", args=("John",), callback=cb)
# cb is called asynchronously which prints
# => "callback got: Hi, John!"
# blocking remote procedure call with 0.1s polling
print(rpc("greet", args=("John",), block=0.1))
# => "Hi, John!"
# shutdown the process
p.stdin.close()
p.stdout.close()
p.terminate()
p.wait()
.. py:attribute:: target
The wrapped target object. Might be *None* when no object is wrapped, e.g. for the *client*
RPC instance.
.. py:attribute:: stdin
The input stream, re-opened with ``"rb"``.
.. py:attribute:: stdout
The output stream, re-opened with ``"wb"``.
.. py:attribute:: watch
The :py:class:`Watchdog` instance that optionally watches *stdin* and dispatches incoming
requests.
"""
EMPTY_RESULT = object()
def __init__(self, handlers=None, stdin=None, stdout=None, watch=True, **kwargs):
super(RPC, self).__init__()
self.handlers = handlers
# open streams
stdin = sys.stdin if stdin is None else stdin
stdout = sys.stdout if stdout is None else stdout
self.stdin = io.open(stdin.fileno(), "rb")
self.stdout = io.open(stdout.fileno(), "wb")
# other attributes
self._i = 0
self._callbacks = {}
self._results = {}
# create and optional start the watchdog
kwargs["start"] = watch
# kwargs.setdefault("daemon", handlers is None)
self.watchdog = Watchdog(self, **kwargs)
def __del__(self):
watchdog = getattr(self, "watchdog", None)
if watchdog:
watchdog.stop()
def __call__(self, *args, **kwargs):
"""
Shorthand for :py:meth:`call`.
"""
return self.call(*args, **kwargs)
def request(
self,
cmd,
args=(),
):
"""
Sends a request to the remote service and waits for the response
"""
q = Queue()
def cb(err, resp):
q.put((err, resp))
self.call(cmd, args=args, callback=cb)
return q.get()
def call(self, method, args=(), kwargs=None, callback=None, block=0):
"""
Performs an actual remote procedure call by writing a request representation (a string) to
the output stream. The remote RPC instance uses *method* to route to the actual method to
call with *args* and *kwargs*. When *callback* is set, it will be called with the result of
the remote call. When *block* is larger than *0*, the calling thread is blocked until the
result is received. In this case, *block* will be the poll interval, emulating synchronuous
return value behavior. When both *callback* is *None* and *block* is *0* or smaller, the
request is considered a notification and the remote RPC instance will not send a response.
"""
# default kwargs
if kwargs is None:
kwargs = {}
# check if the call is a notification
is_notification = callback is None and block <= 0
# create a new id for requests expecting a response
id = None
if not is_notification:
self._i += 1
id = self._i
# register the callback
if callback is not None:
self._callbacks[id] = callback
# store an empty result for the meantime
if block > 0:
self._results[id] = self.EMPTY_RESULT
# create the request
req = Spec.request(method, id=id, params=args)
self._write(req)
# blocking return value behavior
if block > 0:
while True:
if self._results[id] != self.EMPTY_RESULT:
result = self._results[id]
del self._results[id]
if isinstance(result, Exception):
raise result
else:
return result
time.sleep(block)
def _handle(self, line):
"""
Handles an incoming *line* and dispatches the parsed object to the request, response, or
error handlers.
"""
obj = json.loads(line)
# dispatch to the correct handler
if "method" in obj:
# request
self._handle_request(obj)
elif "error" not in obj:
# response
self._handle_response(obj)
else:
# error
self._handle_error(obj)
def _handle_request(self, req):
"""
Handles an incoming request *req*. When it containes an id, a response or error is sent
back.
"""
logging.debug(f"Handling request to {req['method']}")
try:
method = self._route(req["method"])
result = method(req["params"])
if "id" in req:
res = Spec.response(req["id"], result)
self._write(res)
except Exception as e:
if "id" in req:
if isinstance(e, RPCError):
err = Spec.error(req["id"], e.code, e.data)
else:
err = Spec.error(req["id"], -32603, str(e))
self._write(err)
def _handle_response(self, res):
"""
Handles an incoming successful response *res*. Blocking calls are resolved and registered
callbacks are invoked with the first error argument being set to *None*.
"""
logging.debug(f"Handling response for {res['id']}: {res}")
# set the result
if res["id"] in self._results:
self._results[res["id"]] = res["result"]
# lookup and invoke the callback
if res["id"] in self._callbacks:
callback = self._callbacks[res["id"]]
del self._callbacks[res["id"]]
callback(None, res["result"])
def _handle_error(self, res):
"""
Handles an incoming failed response *res*. Blocking calls throw an exception and
registered callbacks are invoked with an exception and the second result argument set to
*None*.
"""
logging.debug(f"Handling error {res}")
# extract the error and create an actual error instance to raise
err = res["error"]
error = get_error(err["code"])(err.get("data", err["message"]))
# set the error
if res["id"] in self._results:
self._results[res["id"]] = error
# lookup and invoke the callback
if res["id"] in self._callbacks:
callback = self._callbacks[res["id"]]
del self._callbacks[res["id"]]
callback(error, None)
def _route(self, method):
if method in self.handlers.keys():
return self.handlers[method]
else:
raise RPCMethodNotFound(data=method)
def _write(self, s):
"""
Writes a string *s* to the output stream.
"""
msg = f"Content-Length: {len(s)}\n\n{s}"
logging.debug("SENT: \n" + str(msg) + "\n\n")
self.stdout.write(bytearray(msg, "utf-8"))
self.stdout.flush()
class Watchdog(threading.Thread):
"""
This class represents a thread that watches the input stream of an :py:class:`RPC` instance for
incoming content and dispatches requests to it.
.. py:attribute:: rpc
The :py:class:`RPC` instance.
.. py:attribute:: name
The thread's name.
.. py:attribute:: interval
The polling interval of the run loop.
.. py:attribute:: daemon
The thread's daemon flag.
"""
def __init__(self, rpc, name="watchdog", interval=0.1, daemon=True, start=True):
super(Watchdog, self).__init__()
# store attributes
self.rpc = rpc
self.name = name
self.interval = interval
self.daemon = daemon
# register a stop event
self._stop = threading.Event()
if start:
self.start()
def start(self):
"""
Starts with thread's activity.
"""
super(Watchdog, self).start()
def stop(self):
"""
Stops with thread's activity.
"""
self._stop.set()
def run(self):
# reset the stop event
self._stop.clear()
# stop here when stdin is not set or closed
if not self.rpc.stdin or self.rpc.stdin.closed:
return
# read new incoming lines
last_pos = 0
while not self._stop.is_set():
lines = None
# stop when stdin is closed
if self.rpc.stdin.closed:
break
# read from stdin depending on whether it is a tty or not
if self.rpc.stdin.isatty():
cur_pos = self.rpc.stdin.tell()
if cur_pos != last_pos:
self.rpc.stdin.seek(last_pos)
lines = self.rpc.stdin.readlines()
last_pos = self.rpc.stdin.tell()
self.rpc.stdin.seek(cur_pos)
else:
try:
header = self.rpc.stdin.readline()
header = header.decode("utf-8").strip()
if header.startswith("Content-Length:"):
length = 2 + int(header[len("Content-Length:") :])
lines = [self.rpc.stdin.read(length)]
except Exception:
# prevent residual race conditions occurring when stdin is closed externally
pass
# handle new lines if any
if lines:
for line in lines:
line = line.decode("utf-8").strip()
if line:
self.rpc._handle(line)
else:
self._stop.wait(self.interval)
class RPCError(Exception):
"""
Base class for RPC errors.
.. py:attribute:: message
The message of this error, i.e., ``"<title> (<code>)[, data: <data>]"``.
.. py:attribute:: data
Additional data of this error. Setting the data attribute will also change the message
attribute.
"""
def __init__(self, data=None):
# build the error message
message = "{} ({})".format(self.title, self.code)
if data is not None:
message += ", data: {}".format(data)
self.message = message
super(RPCError, self).__init__(message)
self.data = data
def __str__(self):
return self.message
error_map_distinct = {}
error_map_range = {}
def is_range(code):
return (
isinstance(code, tuple)
and len(code) == 2
and all(isinstance(i, int) for i in code)
and code[0] < code[1]
)
def register_error(cls):
"""
Decorator that registers a new RPC error derived from :py:class:`RPCError`. The purpose of
error registration is to have a mapping of error codes/code ranges to error classes for faster
lookups during error creation.
.. code-block:: python
@register_error
class MyCustomRPCError(RPCError):
code = ...
title = "My custom error"
"""
# it would be much cleaner to add a meta class to RPCError as a registry for codes
# but in CPython 2 exceptions aren't types, so simply provide a registry mechanism here
if not issubclass(cls, RPCError):
raise TypeError("'{}' is not a subclass of RPCError".format(cls))
code = cls.code
if isinstance(code, int):
error_map = error_map_distinct
elif is_range(code):
error_map = error_map_range
else:
raise TypeError("invalid RPC error code {}".format(code))
if code in error_map:
raise AttributeError("duplicate RPC error code {}".format(code))
error_map[code] = cls
return cls
def get_error(code):
"""
Returns the RPC error class that was previously registered to *code*. *None* is returned when no
class could be found.
"""
if code in error_map_distinct:
return error_map_distinct[code]
for (lower, upper), cls in error_map_range.items():
if lower <= code <= upper:
return cls
return None
@register_error
class RPCParseError(RPCError):
code = -32700
title = "Parse error"
@register_error
class RPCInvalidRequest(RPCError):
code = -32600
title = "Invalid Request"
@register_error
class RPCMethodNotFound(RPCError):
code = -32601
title = "Method not found"
@register_error
class RPCInvalidParams(RPCError):
code = -32602
title = "Invalid params"
@register_error
class RPCInternalError(RPCError):
code = -32603
title = "Internal error"
@register_error
class RPCServerError(RPCError):
code = (-32099, -32000)
title = "Server error"
You can’t perform that action at this time.