84 lines
1.8 KiB
Python
84 lines
1.8 KiB
Python
import struct
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import cPickle
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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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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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yield Batch(items)
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def dump_pickle(obj):
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return cPickle.dumps(obj, 2)
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load_pickle = cPickle.loads
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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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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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def write_int(value, stream):
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stream.write(struct.pack("!i", value))
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def write_with_length(obj, stream):
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write_int(len(obj), stream)
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stream.write(obj)
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def read_with_length(stream):
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length = read_int(stream)
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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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def read_from_pickle_file(stream):
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try:
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while True:
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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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except EOFError:
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return
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