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
|
# Coroutine implementation using Python threads.
#
# Combines ideas from Guido's Generator module, and from the coroutine
# features of Icon and Simula 67.
#
# To run a collection of functions as coroutines, you need to create
# a Coroutine object to control them:
# co = Coroutine()
# and then 'create' a subsidiary object for each function in the
# collection:
# cof1 = co.create(f1 [, arg1, arg2, ...]) # [] means optional,
# cof2 = co.create(f2 [, arg1, arg2, ...]) #... not list
# cof3 = co.create(f3 [, arg1, arg2, ...])
# etc. The functions need not be distinct; 'create'ing the same
# function multiple times gives you independent instances of the
# function.
#
# To start the coroutines running, use co.tran on one of the create'd
# functions; e.g., co.tran(cof2). The routine that first executes
# co.tran is called the "main coroutine". It's special in several
# respects: it existed before you created the Coroutine object; if any of
# the create'd coroutines exits (does a return, or suffers an unhandled
# exception), EarlyExit error is raised in the main coroutine; and the
# co.detach() method transfers control directly to the main coroutine
# (you can't use co.tran() for this because the main coroutine doesn't
# have a name ...).
#
# Coroutine objects support these methods:
#
# handle = .create(func [, arg1, arg2, ...])
# Creates a coroutine for an invocation of func(arg1, arg2, ...),
# and returns a handle ("name") for the coroutine so created. The
# handle can be used as the target in a subsequent .tran().
#
# .tran(target, data=None)
# Transfer control to the create'd coroutine "target", optionally
# passing it an arbitrary piece of data. To the coroutine A that does
# the .tran, .tran acts like an ordinary function call: another
# coroutine B can .tran back to it later, and if it does A's .tran
# returns the 'data' argument passed to B's tran. E.g.,
#
# in coroutine coA in coroutine coC in coroutine coB
# x = co.tran(coC) co.tran(coB) co.tran(coA,12)
# print x # 12
#
# The data-passing feature is taken from Icon, and greatly cuts
# the need to use global variables for inter-coroutine communication.
#
# .back( data=None )
# The same as .tran(invoker, data=None), where 'invoker' is the
# coroutine that most recently .tran'ed control to the coroutine
# doing the .back. This is akin to Icon's "&source".
#
# .detach( data=None )
# The same as .tran(main, data=None), where 'main' is the
# (unnameable!) coroutine that started it all. 'main' has all the
# rights of any other coroutine: upon receiving control, it can
# .tran to an arbitrary coroutine of its choosing, go .back to
# the .detach'er, or .kill the whole thing.
#
# .kill()
# Destroy all the coroutines, and return control to the main
# coroutine. None of the create'ed coroutines can be resumed after a
# .kill(). An EarlyExit exception does a .kill() automatically. It's
# a good idea to .kill() coroutines you're done with, since the
# current implementation consumes a thread for each coroutine that
# may be resumed.
import thread
import sync
class _CoEvent:
def __init__(self, func):
self.f = func
self.e = sync.event()
def __repr__(self):
if self.f is None:
return 'main coroutine'
else:
return 'coroutine for func ' + self.f.func_name
def __hash__(self):
return id(self)
def __cmp__(x,y):
return cmp(id(x), id(y))
def resume(self):
self.e.post()
def wait(self):
self.e.wait()
self.e.clear()
Killed = 'Coroutine.Killed'
EarlyExit = 'Coroutine.EarlyExit'
class Coroutine:
def __init__(self):
self.active = self.main = _CoEvent(None)
self.invokedby = {self.main: None}
self.killed = 0
self.value = None
self.terminated_by = None
def create(self, func, *args):
me = _CoEvent(func)
self.invokedby[me] = None
thread.start_new_thread(self._start, (me,) + args)
return me
def _start(self, me, *args):
me.wait()
if not self.killed:
try:
try:
me.f(*args)
except Killed:
pass
finally:
if not self.killed:
self.terminated_by = me
self.kill()
def kill(self):
if self.killed:
raise TypeError, 'kill() called on dead coroutines'
self.killed = 1
for coroutine in self.invokedby.keys():
coroutine.resume()
def back(self, data=None):
return self.tran( self.invokedby[self.active], data )
def detach(self, data=None):
return self.tran( self.main, data )
def tran(self, target, data=None):
if not self.invokedby.has_key(target):
raise TypeError, '.tran target %r is not an active coroutine' % (target,)
if self.killed:
raise TypeError, '.tran target %r is killed' % (target,)
self.value = data
me = self.active
self.invokedby[target] = me
self.active = target
target.resume()
me.wait()
if self.killed:
if self.main is not me:
raise Killed
if self.terminated_by is not None:
raise EarlyExit, '%r terminated early' % (self.terminated_by,)
return self.value
# end of module
|
