mindspore2022/mindspore/mindrecord/shardreader.py

109 lines
3.3 KiB
Python

# Copyright 2019 Huawei Technologies Co., Ltd
#
# Licensed 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.
# ==============================================================================
"""
This module is to read data from mindrecord.
"""
import mindspore._c_mindrecord as ms
from mindspore import log as logger
from .common.exceptions import MRMOpenError, MRMLaunchError
__all__ = ['ShardReader']
class ShardReader:
"""
Wrapper class which is represent ShardReader class in c++ module.
The class would read a batch of data from MindRecord File series.
"""
def __init__(self):
self._reader = ms.ShardReader()
def open(self, file_name, num_consumer=4, columns=None, operator=None):
"""
Open file and prepare to read MindRecord File.
Args:
file_name (str, list[str]): File names of MindRecord File.
num_consumer (int): Number of worker threads which load data in parallel. Default: 4.
columns (list[str]): List of fields which correspond data would be read.
operator(int): Reserved parameter for operators. Default: None.
Returns:
MSRStatus, SUCCESS or FAILED.
Raises:
MRMOpenError: If failed to open MindRecord File.
"""
columns = columns if columns else []
operator = operator if operator else []
if isinstance(file_name, list):
load_dataset = False
else:
load_dataset = True
file_name = [file_name]
ret = self._reader.open(file_name, load_dataset, num_consumer, columns, operator)
if ret != ms.MSRStatus.SUCCESS:
logger.error("Failed to open {}.".format(file_name))
self.close()
raise MRMOpenError
return ret
def launch(self):
"""
Launch the worker threads to load data.
Returns:
MSRStatus, SUCCESS or FAILED.
Raises:
MRMLaunchError: If failed to launch worker threads.
"""
ret = self._reader.launch()
if ret != ms.MSRStatus.SUCCESS:
logger.error("Failed to launch worker threads.")
raise MRMLaunchError
return ret
def get_next(self):
"""
Return a batch of data including blob data and raw data.
Returns:
list of dict.
"""
return self._reader.get_next()
def get_blob_fields(self):
"""
Return blob fields of MindRecord.
Returns:
list of str.
"""
return self._reader.get_blob_fields()
def get_header(self):
"""
Return header of MindRecord.
Returns:
pointer object refer to header.
"""
return self._reader.get_header()
def close(self):
"""close MindRecord File."""
self._reader.close()