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
|
# Copyright 2015-2016, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * 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.
# * Neither the name of Google Inc. 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 THE COPYRIGHT
# OWNER 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.
"""Helpful utilities related to the stream module."""
import logging
import threading
from grpc.framework.foundation import stream
_NO_VALUE = object()
class TransformingConsumer(stream.Consumer):
"""A stream.Consumer that passes a transformation of its input to another."""
def __init__(self, transformation, downstream):
self._transformation = transformation
self._downstream = downstream
def consume(self, value):
self._downstream.consume(self._transformation(value))
def terminate(self):
self._downstream.terminate()
def consume_and_terminate(self, value):
self._downstream.consume_and_terminate(self._transformation(value))
class IterableConsumer(stream.Consumer):
"""A Consumer that when iterated over emits the values it has consumed."""
def __init__(self):
self._condition = threading.Condition()
self._values = []
self._active = True
def consume(self, stock_reply):
with self._condition:
if self._active:
self._values.append(stock_reply)
self._condition.notify()
def terminate(self):
with self._condition:
self._active = False
self._condition.notify()
def consume_and_terminate(self, stock_reply):
with self._condition:
if self._active:
self._values.append(stock_reply)
self._active = False
self._condition.notify()
def __iter__(self):
return self
def __next__(self):
return self.next()
def next(self):
with self._condition:
while self._active and not self._values:
self._condition.wait()
if self._values:
return self._values.pop(0)
else:
raise StopIteration()
class ThreadSwitchingConsumer(stream.Consumer):
"""A Consumer decorator that affords serialization and asynchrony."""
def __init__(self, sink, pool):
self._lock = threading.Lock()
self._sink = sink
self._pool = pool
# True if self._spin has been submitted to the pool to be called once and
# that call has not yet returned, False otherwise.
self._spinning = False
self._values = []
self._active = True
def _spin(self, sink, value, terminate):
while True:
try:
if value is _NO_VALUE:
sink.terminate()
elif terminate:
sink.consume_and_terminate(value)
else:
sink.consume(value)
except Exception as e: # pylint:disable=broad-except
logging.exception(e)
with self._lock:
if terminate:
self._spinning = False
return
elif self._values:
value = self._values.pop(0)
terminate = not self._values and not self._active
elif not self._active:
value = _NO_VALUE
terminate = True
else:
self._spinning = False
return
def consume(self, value):
with self._lock:
if self._active:
if self._spinning:
self._values.append(value)
else:
self._pool.submit(self._spin, self._sink, value, False)
self._spinning = True
def terminate(self):
with self._lock:
if self._active:
self._active = False
if not self._spinning:
self._pool.submit(self._spin, self._sink, _NO_VALUE, True)
self._spinning = True
def consume_and_terminate(self, value):
with self._lock:
if self._active:
self._active = False
if self._spinning:
self._values.append(value)
else:
self._pool.submit(self._spin, self._sink, value, True)
self._spinning = True
|
