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# Copyright (c) OpenMMLab. All rights reserved.
import os
import os.path as osp
import shutil
import warnings
import mmcv
from mmocr import digit_version
from mmocr.utils import list_from_file
class LmdbAnnFileBackend:
"""Lmdb storage backend for annotation file.
Args:
lmdb_path (str): Lmdb file path.
"""
def __init__(self, lmdb_path, encoding='utf8'):
self.lmdb_path = lmdb_path
self.encoding = encoding
env = self._get_env()
with env.begin(write=False) as txn:
self.total_number = int(
txn.get('total_number'.encode('utf-8')).decode(self.encoding))
def __getitem__(self, index):
"""Retrieve one line from lmdb file by index."""
# only attach env to self when __getitem__ is called
# because env object cannot be pickle
if not hasattr(self, 'env'):
self.env = self._get_env()
with self.env.begin(write=False) as txn:
line = txn.get(str(index).encode('utf-8')).decode(self.encoding)
return line
def __len__(self):
return self.total_number
def _get_env(self):
try:
import lmdb
except ImportError:
raise ImportError(
'Please install lmdb to enable LmdbAnnFileBackend.')
return lmdb.open(
self.lmdb_path,
max_readers=1,
readonly=True,
lock=False,
readahead=False,
meminit=False,
)
def close(self):
self.env.close()
class HardDiskAnnFileBackend:
"""Load annotation file with raw hard disks storage backend."""
def __init__(self, file_format='txt'):
assert file_format in ['txt', 'lmdb']
self.file_format = file_format
def __call__(self, ann_file):
if self.file_format == 'lmdb':
return LmdbAnnFileBackend(ann_file)
return list_from_file(ann_file)
class PetrelAnnFileBackend:
"""Load annotation file with petrel storage backend."""
def __init__(self, file_format='txt', save_dir='tmp_dir'):
assert file_format in ['txt', 'lmdb']
self.file_format = file_format
self.save_dir = save_dir
def __call__(self, ann_file):
file_client = mmcv.FileClient(backend='petrel')
if self.file_format == 'lmdb':
mmcv_version = digit_version(mmcv.__version__)
if mmcv_version < digit_version('1.3.16'):
raise Exception('Please update mmcv to 1.3.16 or higher '
'to enable "get_local_path" of "FileClient".')
assert file_client.isdir(ann_file)
files = file_client.list_dir_or_file(ann_file)
ann_file_rel_path = ann_file.split('s3://')[-1]
ann_file_dir = osp.dirname(ann_file_rel_path)
ann_file_name = osp.basename(ann_file_rel_path)
local_dir = osp.join(self.save_dir, ann_file_dir, ann_file_name)
if osp.exists(local_dir):
warnings.warn(
f'local_ann_file: {local_dir} is already existed and '
'will be used. If it is not the correct ann_file '
'corresponding to {ann_file}, please remove it or '
'change "save_dir" first then try again.')
else:
os.makedirs(local_dir, exist_ok=True)
print(f'Fetching {ann_file} to {local_dir}...')
for each_file in files:
tmp_file_path = file_client.join_path(ann_file, each_file)
with file_client.get_local_path(
tmp_file_path) as local_path:
shutil.copy(local_path, osp.join(local_dir, each_file))
return LmdbAnnFileBackend(local_dir)
lines = str(file_client.get(ann_file), encoding='utf-8').split('\n')
return [x for x in lines if x.strip() != '']
class HTTPAnnFileBackend:
"""Load annotation file with http storage backend."""
def __init__(self, file_format='txt'):
assert file_format in ['txt', 'lmdb']
self.file_format = file_format
def __call__(self, ann_file):
file_client = mmcv.FileClient(backend='http')
if self.file_format == 'lmdb':
raise NotImplementedError(
'Loading lmdb file on http is not supported yet.')
lines = str(file_client.get(ann_file), encoding='utf-8').split('\n')
return [x for x in lines if x.strip() != '']