storagelevel.py

#
# Licensed to the Apache Software Foundation (ASF) under one or more
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# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
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#    http://www.apache.org/licenses/LICENSE-2.0
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__all__ = ["StorageLevel"]


class StorageLevel:
    """
    Flags for controlling the storage of an RDD. Each StorageLevel records whether to use memory,
    whether to drop the RDD to disk if it falls out of memory, whether to keep the data in memory
    in a serialized format, and whether to replicate the RDD partitions on multiple nodes.
    Also contains static constants for some commonly used storage levels, such as MEMORY_ONLY.
    """

    def __init__(self, useDisk, useMemory, useOffHeap, deserialized, replication=1):
        self.useDisk = useDisk
        self.useMemory = useMemory
        self.useOffHeap = useOffHeap
        self.deserialized = deserialized
        self.replication = replication

    def __repr__(self):
        return "StorageLevel(%s, %s, %s, %s, %s)" % (
            self.useDisk, self.useMemory, self.useOffHeap, self.deserialized, self.replication)

    def __str__(self):
        result = ""
        result += "Disk " if self.useDisk else ""
        result += "Memory " if self.useMemory else ""
        result += "Tachyon " if self.useOffHeap else ""
        result += "Deserialized " if self.deserialized else "Serialized "
        result += "%sx Replicated" % self.replication
        return result

StorageLevel.DISK_ONLY = StorageLevel(True, False, False, False)
StorageLevel.DISK_ONLY_2 = StorageLevel(True, False, False, False, 2)
StorageLevel.MEMORY_ONLY = StorageLevel(False, True, False, True)
StorageLevel.MEMORY_ONLY_2 = StorageLevel(False, True, False, True, 2)
StorageLevel.MEMORY_ONLY_SER = StorageLevel(False, True, False, False)
StorageLevel.MEMORY_ONLY_SER_2 = StorageLevel(False, True, False, False, 2)
StorageLevel.MEMORY_AND_DISK = StorageLevel(True, True, False, True)
StorageLevel.MEMORY_AND_DISK_2 = StorageLevel(True, True, False, True, 2)
StorageLevel.MEMORY_AND_DISK_SER = StorageLevel(True, True, False, False)
StorageLevel.MEMORY_AND_DISK_SER_2 = StorageLevel(True, True, False, False, 2)
StorageLevel.OFF_HEAP = StorageLevel(False, False, True, False, 1)