1# Copyright 2012 the V8 project authors. All rights reserved.
2# Redistribution and use in source and binary forms, with or without
3# modification, are permitted provided that the following conditions are
4# met:
5#
6#     * Redistributions of source code must retain the above copyright
7#       notice, this list of conditions and the following disclaimer.
8#     * Redistributions in binary form must reproduce the above
9#       copyright notice, this list of conditions and the following
10#       disclaimer in the documentation and/or other materials provided
11#       with the distribution.
12#     * Neither the name of Google Inc. nor the names of its
13#       contributors may be used to endorse or promote products derived
14#       from this software without specific prior written permission.
15#
16# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28
29import cStringIO as StringIO
30try:
31  import ujson as json
32except ImportError:
33  import json
34import os
35import struct
36import zlib
37
38from . import constants
39
40def Send(obj, sock):
41  """
42  Sends a JSON encodable object over the specified socket (zlib-compressed).
43  """
44  obj = json.dumps(obj)
45  compression_level = 2  # 1 = fastest, 9 = best compression
46  compressed = zlib.compress(obj, compression_level)
47  payload = struct.pack('>i', len(compressed)) + compressed
48  sock.sendall(payload)
49
50
51class Receiver(object):
52  def __init__(self, sock):
53    self.sock = sock
54    self.data = StringIO.StringIO()
55    self.datalength = 0
56    self._next = self._GetNext()
57
58  def IsDone(self):
59    return self._next == None
60
61  def Current(self):
62    return self._next
63
64  def Advance(self):
65    try:
66      self._next = self._GetNext()
67    except:
68      raise
69
70  def _GetNext(self):
71    try:
72      while self.datalength < constants.SIZE_T:
73        try:
74          chunk = self.sock.recv(8192)
75        except:
76          raise
77        if not chunk: return None
78        self._AppendData(chunk)
79      size = self._PopData(constants.SIZE_T)
80      size = struct.unpack(">i", size)[0]
81      while self.datalength < size:
82        try:
83          chunk = self.sock.recv(8192)
84        except:
85          raise
86        if not chunk: return None
87        self._AppendData(chunk)
88      result = self._PopData(size)
89      result = zlib.decompress(result)
90      result = json.loads(result)
91      if result == constants.END_OF_STREAM:
92        return None
93      return result
94    except:
95      raise
96
97  def _AppendData(self, new):
98    self.data.seek(0, os.SEEK_END)
99    self.data.write(new)
100    self.datalength += len(new)
101
102  def _PopData(self, length):
103    self.data.seek(0)
104    chunk = self.data.read(length)
105    remaining = self.data.read()
106    self.data.close()
107    self.data = StringIO.StringIO()
108    self.data.write(remaining)
109    assert self.datalength - length == len(remaining)
110    self.datalength = len(remaining)
111    return chunk
112