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      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 
     29 import cStringIO as StringIO
     30 try:
     31   import ujson as json
     32 except ImportError:
     33   import json
     34 import os
     35 import struct
     36 import zlib
     37 
     38 from . import constants
     39 
     40 def 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 
     51 class 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