2013-07-16 20:21:33 -04:00
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#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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2012-08-18 19:07:10 -04:00
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import struct
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2012-08-25 19:46:07 -04:00
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import cPickle
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2012-08-10 04:10:02 -04:00
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2012-12-26 20:34:24 -05:00
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class Batch(object):
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"""
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Used to store multiple RDD entries as a single Java object.
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This relieves us from having to explicitly track whether an RDD
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is stored as batches of objects and avoids problems when processing
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the union() of batched and unbatched RDDs (e.g. the union() of textFile()
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with another RDD).
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"""
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def __init__(self, items):
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self.items = items
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def batched(iterator, batchSize):
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2012-12-29 18:34:57 -05:00
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if batchSize == -1: # unlimited batch size
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yield Batch(list(iterator))
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else:
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items = []
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count = 0
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for item in iterator:
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items.append(item)
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count += 1
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if count == batchSize:
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yield Batch(items)
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items = []
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count = 0
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if items:
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2012-12-26 20:34:24 -05:00
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yield Batch(items)
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2012-08-25 19:46:07 -04:00
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def dump_pickle(obj):
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return cPickle.dumps(obj, 2)
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2012-08-10 04:10:02 -04:00
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2012-08-25 19:46:07 -04:00
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load_pickle = cPickle.loads
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2012-08-10 04:10:02 -04:00
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2012-10-19 13:24:49 -04:00
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def read_long(stream):
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length = stream.read(8)
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if length == "":
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raise EOFError
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return struct.unpack("!q", length)[0]
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2013-03-10 16:54:46 -04:00
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def write_long(value, stream):
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stream.write(struct.pack("!q", value))
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2012-10-19 13:24:49 -04:00
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def read_int(stream):
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length = stream.read(4)
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if length == "":
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raise EOFError
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return struct.unpack("!i", length)[0]
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2013-01-20 04:57:44 -05:00
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def write_int(value, stream):
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stream.write(struct.pack("!i", value))
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2012-08-25 19:46:07 -04:00
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def write_with_length(obj, stream):
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2013-01-20 04:57:44 -05:00
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write_int(len(obj), stream)
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2012-08-18 19:07:10 -04:00
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stream.write(obj)
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2012-08-10 04:10:02 -04:00
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2012-08-25 19:46:07 -04:00
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def read_with_length(stream):
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2012-10-19 13:24:49 -04:00
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length = read_int(stream)
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2012-08-18 19:07:10 -04:00
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obj = stream.read(length)
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if obj == "":
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raise EOFError
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return obj
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2012-12-24 20:20:10 -05:00
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def read_from_pickle_file(stream):
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try:
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while True:
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2012-12-26 20:34:24 -05:00
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obj = load_pickle(read_with_length(stream))
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if type(obj) == Batch: # We don't care about inheritance
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for item in obj.items:
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yield item
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else:
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yield obj
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2012-12-24 20:20:10 -05:00
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except EOFError:
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return
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