python/src/datasketches_spark/common.py

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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
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from pyspark import SparkContext
from pyspark.sql.column import Column, _to_java_column, _to_seq, _create_column_from_literal
from pyspark.sql.utils import try_remote_functions
from py4j.java_gateway import JavaClass
from typing import Any, TypeVar, Union, Callable
from functools import lru_cache
from ._version import __version__


import os
from importlib.resources import files, as_file

ColumnOrName = Union[Column, str]
ColumnOrName_ = TypeVar("ColumnOrName_", bound=ColumnOrName)

def get_dependency_path(filename: str) -> str:
    """
    Returns a list of absolute paths to the specified file,\n
    it is included in the package's /deps subdir.
    :param filename: Name of file to retrieve
    :return: Absolute paths to filename
    :exception FileNotFoundError: If a file is not found in the package
    """
    try:
        with as_file(files("datasketches_spark.deps") / filename) as file_path:
            return str(file_path)
    except FileNotFoundError:
        raise FileNotFoundError(f"File {filename} not found in datasketches_spark.deps")

def get_dependency_classpath() -> list[str]:
    """
    Returns a list of absolute paths to the jar files included in the package.\n
    Assumes that the jar files are located in the package's /deps subdir.
    """

    # we need whatever is listed in dependencies.txt as well as
    # datasketches-spark_<scala_veersion>-<ds-spark_version>.jar
    jar_files = []
    with (files("datasketches_spark.deps") / "dependencies.txt").open('r') as dependencies:
        for dep in dependencies:
            jar_files.append(dep.strip())
    ds_spark_version = __version__
    jar_files.append(f"datasketches-spark_{os.environ.get('SCALA_VERSION', '2.12')}-{ds_spark_version}.jar")

    return ":".join([get_dependency_path(jar) for jar in jar_files])


# Since we have functions from different packages, rather than the
# single 16k+ line functions class in core Spark, we'll have each
# sketch family grab its own functions class from the JVM and cache it

def _get_jvm_class(name: str) -> JavaClass:
    """
    Retrieves JVM class identified by name from
    Java gateway associated with the current active Spark context.
    """
    assert SparkContext._active_spark_context is not None
    return getattr(SparkContext._active_spark_context._jvm, name)

@lru_cache
def _get_jvm_function(cls: JavaClass, name: str) -> Callable:
    """
    Retrieves JVM function identified by name from
    Java gateway associated with sc.
    """
    assert cls is not None
    return getattr(cls, name)

def _invoke_function(cls: JavaClass, name: str, *args: Any) -> Column:
    """
    Invokes JVM function identified by name with args
    and wraps the result with :class:`~pyspark.sql.Column`.
    """
    #assert SparkContext._active_spark_context is not None
    assert cls is not None
    jf = _get_jvm_function(cls, name)
    return Column(jf(*args))


def _invoke_function_over_columns(cls: JavaClass, name: str, *cols: "ColumnOrName") -> Column:
    """
    Invokes n-ary JVM function identified by name
    and wraps the result with :class:`~pyspark.sql.Column`.
    """
    return _invoke_function(cls, name, *(_to_java_column(col) for col in cols))


# lazy init so we know the SparkContext exists first
_spark_functions_class: JavaClass = None

def _get_spark_functions_class() -> JavaClass:
    global _spark_functions_class
    if _spark_functions_class is None:
        _spark_functions_class = _get_jvm_class("org.apache.spark.sql.functions")
    return _spark_functions_class

# borrowed from PySpark
def _array_as_java_column(data: Union[list, tuple]) -> Column:
    """
    Converts a Python list or tuple to a Spark DataFrame column.
    """
    sc = SparkContext._active_spark_context
    col = _to_seq(sc, [_create_column_from_literal(x) for x in data])
    return _invoke_function(_get_spark_functions_class(), "array", col)._jc
    #return _invoke_function(_get_spark_functions_class(), "array", _to_seq(sc, [_create_column_from_literal(x) for x in data]))._jc


_common_functions_class: JavaClass = None

def _get_common_functions_class() -> JavaClass:
    global _common_functions_class
    if _common_functions_class is None:
        _common_functions_class = _get_jvm_class("org.apache.spark.sql.datasketches.common.functions")
    return _common_functions_class


@try_remote_functions
def cast_to_binary(col: "ColumnOrName") -> Column:
    return _invoke_function_over_columns(_get_common_functions_class(), "cast_to_binary", col)