Skip to content

Commit bb69e66

Browse files
laixintaolaixintao
committed
finish ch4.4 asyncio.coroutines
1 parent 8ac22e2 commit bb69e66

File tree

1 file changed

+165
-2
lines changed

1 file changed

+165
-2
lines changed

‎chapter4/04_Handing_corotines_with_Asyncio.rst

Lines changed: 165 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,169 @@ yield表示协程在此暂停，并且将执行权交给其他协程。因为协
2828

2929
在这个例子中，我们将看到如何使用Asyncio的协程来模拟有限状态机。有限状态机(finite state machine or automaton, FSA)是一个数据血腥，不仅在工程领域应用广泛，在科学领域也很著名，例如数学和计算机科学等。我们要模拟的状态机如下图所示：
3030

31-
.. images:: ../images/finite-state-machine.png
31+
.. image:: ../images/finite-state-machine.png
3232

33-
在上图中，可以看到我们的系统有 **S1**, **S2****, **S3**, **S4** 四个状态, **0** 和 **1** 是状态机可以从一个状态到另一个状态的值（这个过程叫做转换）。例如在本实验中，只有当只为1的时候， **S0** 可以转换到 **S1** ，当只为0的时候， **S0** 可以转换到 **S2** .Python代码如下，状态模拟从 **S0** 开始，叫做 **初始状态** ，最后到 **S4** ，叫做 **结束状态** 。
33+
在上图中，可以看到我们的系统有 **S1**, **S2****, **S3**, **S4** 四个状态, **0** 和 **1** 是状态机可以从一个状态到另一个状态的值（这个过程叫做转换）。例如在本实验中，只有当只为1的时候， **S0** 可以转换到 **S1** ，当只为0的时候， **S0** 可以转换到 **S2** .Python代码如下，状态模拟从 **S0** 开始，叫做 **初始状态** ，最后到 **S4** ，叫做 **结束状态** 。 ::
34+
35+
# Asyncio Finite State Machine
36+
import asyncio
37+
import time
38+
from random import randint
39+
40+
41+
@asyncio.coroutine
42+
def StartState():
43+
print("Start State called \n")
44+
input_value = randint(0, 1)
45+
time.sleep(1)
46+
if (input_value == 0):
47+
result = yield from State2(input_value)
48+
else:
49+
result = yield from State1(input_value)
50+
print("Resume of the Transition : \nStart State calling " + result)
51+
52+
@asyncio.coroutine
53+
def State1(transition_value):
54+
outputValue = str("State 1 with transition value = %s \n" % transition_value)
55+
input_value = randint(0, 1)
56+
time.sleep(1)
57+
print("...Evaluating...")
58+
if input_value == 0:
59+
result = yield from State3(input_value)
60+
else :
61+
result = yield from State2(input_value)
62+
result = "State 1 calling " + result
63+
return outputValue + str(result)
64+
65+
@asyncio.coroutine
66+
def State2(transition_value):
67+
outputValue = str("State 2 with transition value = %s \n" % transition_value)
68+
input_value = randint(0, 1)
69+
time.sleep(1)
70+
print("...Evaluating...")
71+
if (input_value == 0):
72+
result = yield from State1(input_value)
73+
else :
74+
result = yield from State3(input_value)
75+
result = "State 2 calling " + result
76+
return outputValue + str(result)
77+
78+
@asyncio.coroutine
79+
def State3(transition_value):
80+
outputValue = str("State 3 with transition value = %s \n" % transition_value)
81+
input_value = randint(0, 1)
82+
time.sleep(1)
83+
print("...Evaluating...")
84+
if (input_value == 0):
85+
result = yield from State1(input_value)
86+
else :
87+
result = yield from EndState(input_value)
88+
result = "State 3 calling " + result
89+
return outputValue + str(result)
90+
91+
@asyncio.coroutine
92+
def EndState(transition_value):
93+
outputValue = str("End State with transition value = %s \n" % transition_value)
94+
print("...Stop Computation...")
95+
return outputValue
96+
97+
if __name__ == "__main__":
98+
print("Finite State Machine simulation with Asyncio Coroutine")
99+
loop = asyncio.get_event_loop()
100+
loop.run_until_complete(StartState())
101+
102+
运行代码，我们可以看到类似以下输出（译注，运行结果随机，这里给我译者运行的三次结果）. ::
103+
104+
$ python3 coroutines.py
105+
Finite State Machine simulation with Asyncio Coroutine
106+
Start State called
107+
108+
...Evaluating...
109+
...Evaluating...
110+
...Evaluating...
111+
...Evaluating...
112+
...Evaluating...
113+
...Evaluating...
114+
...Stop Computation...
115+
Resume of the Transition :
116+
Start State calling State 2 with transition value = 0
117+
State 2 calling State 1 with transition value = 0
118+
State 1 calling State 2 with transition value = 1
119+
State 2 calling State 1 with transition value = 0
120+
State 1 calling State 2 with transition value = 1
121+
State 2 calling State 3 with transition value = 1
122+
State 3 calling End State with transition value = 1
123+
124+
$ python3 coroutines.py
125+
Finite State Machine simulation with Asyncio Coroutine
126+
Start State called
127+
128+
...Evaluating...
129+
...Evaluating...
130+
...Stop Computation...
131+
Resume of the Transition :
132+
Start State calling State 2 with transition value = 0
133+
State 2 calling State 3 with transition value = 1
134+
State 3 calling End State with transition value = 1
135+
136+
$ python3 coroutines.py
137+
Finite State Machine simulation with Asyncio Coroutine
138+
Start State called
139+
140+
...Evaluating...
141+
...Evaluating...
142+
...Evaluating...
143+
...Evaluating...
144+
...Evaluating...
145+
...Evaluating...
146+
...Evaluating...
147+
...Stop Computation...
148+
Resume of the Transition :
149+
Start State calling State 1 with transition value = 1
150+
State 1 calling State 2 with transition value = 1
151+
State 2 calling State 1 with transition value = 0
152+
State 1 calling State 3 with transition value = 0
153+
State 3 calling State 1 with transition value = 0
154+
State 1 calling State 2 with transition value = 1
155+
State 2 calling State 3 with transition value = 1
156+
State 3 calling End State with transition value = 1
157+
158+
|work|
159+
------
160+
161+
每一个状态都由装饰器装饰： ::
162+
163+
@asyncio.coroutine
164+
165+
例如， **S0** 的定义如下所示： ::
166+
167+
@asyncio.coroutine
168+
def StartState():
169+
print("Start State called \n")
170+
input_value = randint(0, 1)
171+
time.sleep(1)
172+
if (input_value == 0):
173+
result = yield from State2(input_value)
174+
else:
175+
result = yield from State1(input_value)
176+
print("Resume of the Transition : \nStart State calling " + result)
177+
178+
通过 ``random`` 模块的 ``randint(0, 1)`` 函数生成了 ``input_value`` 的值，决定了下一个转换状态。此函数随机生成1或0： ::
179+
180+
input_value = randint(0, 1)
181+
182+
得到 ``input_value`` 的值之后，通过 ``yield from`` 命令调用下一个协程。 ::
183+
184+
if (input_value == 0):
185+
result = yield from State2(input_value)
186+
else:
187+
result = yield from State1(input_value)
188+
189+
``result`` 是下一个协程返回的string，这样我们在计算的最后就可以重新构造出计算过程。
190+
191+
启动事件循环的代码如下： ::
192+
193+
if __name__ == "__main__":
194+
print("Finite State Machine simulation with Asyncio Coroutine")
195+
loop = asyncio.get_event_loop()
196+
loop.run_until_complete(StartState())

0 commit comments

Comments
 (0)