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# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with 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 the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
"""
Functions to interact with Arrow memory allocated by Arrow Java.
These functions convert the objects holding the metadata, the actual
data is not copied at all.
This will only work with a JVM running in the same process such as provided
through jpype. Modules that talk to a remote JVM like py4j will not work as the
memory addresses reported by them are not reachable in the python process.
"""
from __future__ import absolute_import
import pyarrow as pa
def jvm_buffer(arrowbuf):
"""
Construct an Arrow buffer from io.netty.buffer.ArrowBuf
Parameters
----------
arrowbuf: io.netty.buffer.ArrowBuf
Arrow Buffer representation on the JVM
Returns
-------
pyarrow.Buffer
Python Buffer that references the JVM memory
"""
address = arrowbuf.memoryAddress()
size = arrowbuf.capacity()
return pa.foreign_buffer(address, size, arrowbuf.asNettyBuffer())
def _from_jvm_int_type(jvm_type):
"""
Convert a JVM int type to its Python equivalent.
Parameters
----------
jvm_type: org.apache.arrow.vector.types.pojo.ArrowType$Int
Returns
-------
typ: pyarrow.DataType
"""
if jvm_type.isSigned:
if jvm_type.bitWidth == 8:
return pa.int8()
elif jvm_type.bitWidth == 16:
return pa.int16()
elif jvm_type.bitWidth == 32:
return pa.int32()
elif jvm_type.bitWidth == 64:
return pa.int64()
else:
if jvm_type.bitWidth == 8:
return pa.uint8()
elif jvm_type.bitWidth == 16:
return pa.uint16()
elif jvm_type.bitWidth == 32:
return pa.uint32()
elif jvm_type.bitWidth == 64:
return pa.uint64()
def _from_jvm_float_type(jvm_type):
"""
Convert a JVM float type to its Python equivalent.
Parameters
----------
jvm_type: org.apache.arrow.vector.types.pojo.ArrowType$FloatingPoint
Returns
-------
typ: pyarrow.DataType
"""
precision = jvm_type.getPrecision().toString()
if precision == 'HALF':
return pa.float16()
elif precision == 'SINGLE':
return pa.float32()
elif precision == 'DOUBLE':
return pa.float64()
def _from_jvm_time_type(jvm_type):
"""
Convert a JVM time type to its Python equivalent.
Parameters
----------
jvm_type: org.apache.arrow.vector.types.pojo.ArrowType$Time
Returns
-------
typ: pyarrow.DataType
"""
time_unit = jvm_type.getUnit().toString()
if time_unit == 'SECOND':
assert jvm_type.bitWidth == 32
return pa.time32('s')
elif time_unit == 'MILLISECOND':
assert jvm_type.bitWidth == 32
return pa.time32('ms')
elif time_unit == 'MICROSECOND':
assert jvm_type.bitWidth == 64
return pa.time64('us')
elif time_unit == 'NANOSECOND':
assert jvm_type.bitWidth == 64
return pa.time64('ns')
def _from_jvm_timestamp_type(jvm_type):
"""
Convert a JVM timestamp type to its Python equivalent.
Parameters
----------
jvm_type: org.apache.arrow.vector.types.pojo.ArrowType$Timestamp
Returns
-------
typ: pyarrow.DataType
"""
time_unit = jvm_type.getUnit().toString()
timezone = jvm_type.getTimezone()
if time_unit == 'SECOND':
return pa.timestamp('s', tz=timezone)
elif time_unit == 'MILLISECOND':
return pa.timestamp('ms', tz=timezone)
elif time_unit == 'MICROSECOND':
return pa.timestamp('us', tz=timezone)
elif time_unit == 'NANOSECOND':
return pa.timestamp('ns', tz=timezone)
def _from_jvm_date_type(jvm_type):
"""
Convert a JVM date type to its Python equivalent
Parameters
----------
jvm_type: org.apache.arrow.vector.types.pojo.ArrowType$Date
Returns
-------
typ: pyarrow.DataType
"""
day_unit = jvm_type.getUnit().toString()
if day_unit == 'DAY':
return pa.date32()
elif day_unit == 'MILLISECOND':
return pa.date64()
def field(jvm_field):
"""
Construct a Field from a org.apache.arrow.vector.types.pojo.Field
instance.
Parameters
----------
jvm_field: org.apache.arrow.vector.types.pojo.Field
Returns
-------
pyarrow.Field
"""
name = jvm_field.getName()
jvm_type = jvm_field.getType()
typ = None
if not jvm_type.isComplex():
type_str = jvm_type.getTypeID().toString()
if type_str == 'Null':
typ = pa.null()
elif type_str == 'Int':
typ = _from_jvm_int_type(jvm_type)
elif type_str == 'FloatingPoint':
typ = _from_jvm_float_type(jvm_type)
elif type_str == 'Utf8':
typ = pa.string()
elif type_str == 'Binary':
typ = pa.binary()
elif type_str == 'FixedSizeBinary':
typ = pa.binary(jvm_type.getByteWidth())
elif type_str == 'Bool':
typ = pa.bool_()
elif type_str == 'Time':
typ = _from_jvm_time_type(jvm_type)
elif type_str == 'Timestamp':
typ = _from_jvm_timestamp_type(jvm_type)
elif type_str == 'Date':
typ = _from_jvm_date_type(jvm_type)
elif type_str == 'Decimal':
typ = pa.decimal128(jvm_type.getPrecision(), jvm_type.getScale())
else:
raise NotImplementedError(
"Unsupported JVM type: {}".format(type_str))
else:
# TODO: The following JVM types are not implemented:
# Struct, List, FixedSizeList, Union, Dictionary
raise NotImplementedError(
"JVM field conversion only implemented for primitive types.")
nullable = jvm_field.isNullable()
if jvm_field.getMetadata().isEmpty():
metadata = None
else:
metadata = dict(jvm_field.getMetadata())
return pa.field(name, typ, nullable, metadata)
def schema(jvm_schema):
"""
Construct a Schema from a org.apache.arrow.vector.types.pojo.Schema
instance.
Parameters
----------
jvm_schema: org.apache.arrow.vector.types.pojo.Schema
Returns
-------
pyarrow.Schema
"""
fields = jvm_schema.getFields()
fields = [field(f) for f in fields]
metadata = jvm_schema.getCustomMetadata()
if metadata.isEmpty():
meta = None
else:
meta = {k: metadata[k] for k in metadata.keySet()}
return pa.schema(fields, meta)
def array(jvm_array):
"""
Construct an (Python) Array from its JVM equivalent.
Parameters
----------
jvm_array : org.apache.arrow.vector.ValueVector
Returns
-------
array : Array
"""
if jvm_array.getField().getType().isComplex():
minor_type_str = jvm_array.getMinorType().toString()
raise NotImplementedError(
"Cannot convert JVM Arrow array of type {},"
" complex types not yet implemented.".format(minor_type_str))
dtype = field(jvm_array.getField()).type
length = jvm_array.getValueCount()
buffers = [jvm_buffer(buf)
for buf in list(jvm_array.getBuffers(False))]
null_count = jvm_array.getNullCount()
return pa.Array.from_buffers(dtype, length, buffers, null_count)
def record_batch(jvm_vector_schema_root):
"""
Construct a (Python) RecordBatch from a JVM VectorSchemaRoot
Parameters
----------
jvm_vector_schema_root : org.apache.arrow.vector.VectorSchemaRoot
Returns
-------
record_batch: pyarrow.RecordBatch
"""
pa_schema = schema(jvm_vector_schema_root.getSchema())
arrays = []
for name in pa_schema.names:
arrays.append(array(jvm_vector_schema_root.getVector(name)))
return pa.RecordBatch.from_arrays(
arrays,
pa_schema.names,
metadata=pa_schema.metadata
)