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
|
execfile("ttime.py")
import cPickle
#######################################################################
#
# iterfile - Convert an iterator to a file object and vice-versa
#
class IterFileException(Exception): pass
class UnwrapFile:
"""Contains some basic methods for parsing a file containing an iter"""
def __init__(self, file):
self.file = file
def _s2l(self, s):
"""Convert string to long int"""
assert len(s) == 7
l = 0L
for i in range(7): l = l*256 + ord(s[i])
return l
def _get(self):
"""Return pair (type, data) next in line on the file
type is a single character which is either "o" for object, "f"
for file, "c" for a continution of a file, or None if no more
data can be read. Data is either the file's data, if type is
"c" or "f", or the actual object if the type is "o".
"""
header = self.file.read(8)
if not header: return None, None
assert len(header) == 8, "Header is only %d bytes" % len(header)
type, length = header[0], self._s2l(header[1:])
buf = self.file.read(length)
if type == "o": return type, cPickle.loads(buf)
else: return type, buf
class IterWrappingFile(UnwrapFile):
"""An iterator generated from a file.
Initialize with a file type object, and then it will return the
elements of the file in order.
"""
def __init__(self, file):
UnwrapFile.__init__(self, file)
self.currently_in_file = None
def __iter__(self): return self
def next(self):
if self.currently_in_file:
self.currently_in_file.close() # no error checking by this point
type, data = self._get()
if not type: raise StopIteration
if type == "o": return data
elif type == "f":
file = IterVirtualFile(self, data)
if data: self.currently_in_file = file
else: self.currently_in_file = None
return file
else: raise IterFileException("Bad file type %s" % type)
class IterVirtualFile(UnwrapFile):
"""Another version of a pretend file
This is returned by IterWrappingFile when a file is embedded in
the main file that the IterWrappingFile is based around.
"""
def __init__(self, iwf, initial_data):
"""Initializer
initial_data is the data from the first block of the file.
iwf is the iter wrapping file that spawned this
IterVirtualFile.
"""
UnwrapFile.__init__(self, iwf.file)
self.iwf = iwf
self.bufferlist = [initial_data]
self.bufferlen = len(initial_data)
self.closed = None
def check_consistency(self):
l = len("".join(self.bufferlist))
assert l == self.bufferlen, \
"Length of IVF bufferlist doesn't match (%s, %s)" % \
(l, self.bufferlen)
def read(self, length):
assert not self.closed
if self.iwf.currently_in_file:
while length >= self.bufferlen:
if not self.addtobuffer(): break
real_len = min(length, self.bufferlen)
combined_buffer = "".join(self.bufferlist)
assert len(combined_buffer) == self.bufferlen, \
(len(combined_buffer), self.bufferlen)
self.bufferlist = [combined_buffer[real_len:]]
self.bufferlen = self.bufferlen - real_len
return combined_buffer[:real_len]
def addtobuffer(self):
"""Read a chunk from the file and add it to the buffer"""
assert self.iwf.currently_in_file
type, data = self._get()
assert type == "c", "Type is %s instead of c" % type
if data:
self.bufferlen = self.bufferlen + len(data)
self.bufferlist.append(data)
return 1
else:
self.iwf.currently_in_file = None
return None
def close(self):
"""Currently just reads whats left and discards it"""
while self.iwf.currently_in_file:
self.addtobuffer()
self.bufferlist = []
self.bufferlen = 0
self.closed = 1
class FileWrappingIter:
"""A file interface wrapping around an iterator
This is initialized with an iterator, and then converts it into a
stream of characters. The object will evaluate as little of the
iterator as is necessary to provide the requested bytes.
The actual file is a sequence of marshaled objects, each preceded
by 8 bytes which identifies the following the type of object, and
specifies its length. File objects are not marshalled, but the
data is written in chunks of Globals.blocksize, and the following
blocks can identify themselves as continuations.
"""
def __init__(self, iter):
"""Initialize with iter"""
self.iter = iter
self.bufferlist = []
self.bufferlen = 0L
self.currently_in_file = None
self.closed = None
def read(self, length):
"""Return next length bytes in file"""
assert not self.closed
while self.bufferlen < length:
if not self.addtobuffer(): break
combined_buffer = "".join(self.bufferlist)
assert len(combined_buffer) == self.bufferlen
real_len = min(self.bufferlen, length)
self.bufferlen = self.bufferlen - real_len
self.bufferlist = [combined_buffer[real_len:]]
return combined_buffer[:real_len]
def addtobuffer(self):
"""Updates self.bufferlist and self.bufferlen, adding on a chunk
Returns None if we have reached the end of the iterator,
otherwise return true.
"""
if self.currently_in_file:
buf = "c" + self.addfromfile()
else:
try: currentobj = self.iter.next()
except StopIteration: return None
if hasattr(currentobj, "read") and hasattr(currentobj, "close"):
self.currently_in_file = currentobj
buf = "f" + self.addfromfile()
else:
pickle = cPickle.dumps(currentobj, 1)
buf = "o" + self._l2s(len(pickle)) + pickle
self.bufferlist.append(buf)
self.bufferlen = self.bufferlen + len(buf)
return 1
def addfromfile(self):
"""Read a chunk from the current file and return it"""
buf = self.currently_in_file.read(Globals.blocksize)
if not buf:
assert not self.currently_in_file.close()
self.currently_in_file = None
return self._l2s(len(buf)) + buf
def _l2s(self, l):
"""Convert long int to string of 7 characters"""
s = ""
for i in range(7):
l, remainder = divmod(l, 256)
s = chr(remainder) + s
assert remainder == 0
return s
def close(self): self.closed = 1
class BufferedRead:
"""Buffer the .read() calls to the given file
This is used to lessen overhead and latency when a file is sent
over a connection.
"""
def __init__(self, file):
self.file = file
self.buffer = ""
self.bufsize = Globals.conn_bufsize
def read(self, l = -1):
if l < 0: # Read as much as possible
result = self.buffer + self.file.read()
self.buffer = ""
return result
if len(self.buffer) < l: # Try to make buffer as long as l
self.buffer += self.file.read(max(self.bufsize,
l - len(self.buffer)))
actual_size = min(l, len(self.buffer))
result = self.buffer[:actual_size]
self.buffer = self.buffer[actual_size:]
return result
def close(self): return self.file.close()
|
