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
|
#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""Base class for implementing RPC of API proxy stubs."""
import sys
class RPC(object):
"""Base class for implementing RPC of API proxy stubs.
To implement a RPC to make real asynchronous API call:
- Extend this class.
- Override _MakeCallImpl and/or _WaitImpl to do a real asynchronous call.
"""
IDLE = 0
RUNNING = 1
FINISHING = 2
def __init__(self, package=None, call=None, request=None, response=None,
callback=None, deadline=None, stub=None):
"""Constructor for the RPC object.
All arguments are optional, and simply set members on the class.
These data members will be overriden by values passed to MakeCall.
Args:
package: string, the package for the call
call: string, the call within the package
request: ProtocolMessage instance, appropriate for the arguments
response: ProtocolMessage instance, appropriate for the response
callback: callable, called when call is complete
deadline: A double specifying the deadline for this call as the number of
seconds from the current time. Ignored if non-positive.
stub: APIProxyStub instance, used in default _WaitImpl to do real call
"""
self.__exception = None
self.__state = RPC.IDLE
self.__traceback = None
self.package = package
self.call = call
self.request = request
self.response = response
self.callback = callback
self.deadline = deadline
self.stub = stub
self.cpu_usage_mcycles = 0
def MakeCall(self, package=None, call=None, request=None, response=None,
callback=None, deadline=None):
"""Makes an asynchronous (i.e. non-blocking) API call within the
specified package for the specified call method.
It will call the _MakeRealCall to do the real job.
Args:
Same as constructor; see __init__.
Raises:
TypeError or AssertionError if an argument is of an invalid type.
AssertionError or RuntimeError is an RPC is already in use.
"""
self.callback = callback or self.callback
self.package = package or self.package
self.call = call or self.call
self.request = request or self.request
self.response = response or self.response
self.deadline = deadline or self.deadline
assert self.__state is RPC.IDLE, ('RPC for %s.%s has already been started' %
(self.package, self.call))
assert self.callback is None or callable(self.callback)
self._MakeCallImpl()
def Wait(self):
"""Waits on the API call associated with this RPC."""
rpc_completed = self._WaitImpl()
assert rpc_completed, ('RPC for %s.%s was not completed, and no other ' +
'exception was raised ' % (self.package, self.call))
def CheckSuccess(self):
"""If there was an exception, raise it now.
Raises:
Exception of the API call or the callback, if any.
"""
if self.exception and self.__traceback:
raise self.exception.__class__, self.exception, self.__traceback
elif self.exception:
raise self.exception
@property
def exception(self):
return self.__exception
@property
def state(self):
return self.__state
def _MakeCallImpl(self):
"""Override this method to implement a real asynchronous call rpc."""
self.__state = RPC.RUNNING
def _WaitImpl(self):
"""Override this method to implement a real asynchronous call rpc.
Returns:
True if the async call was completed successfully.
"""
try:
try:
self.stub.MakeSyncCall(self.package, self.call,
self.request, self.response)
except Exception, e:
self.__exception = e
finally:
self.__state = RPC.FINISHING
self.__Callback()
return True
def __Callback(self):
if self.callback:
try:
self.callback()
except:
exc_class, self.__exception, self.__traceback = sys.exc_info()
self.__exception._appengine_apiproxy_rpc = self
raise
|
