2022-04-13 09:40:22 +02:00

311 lines
10 KiB
Python

# Copyright 2020-2022 Ternaris.
# SPDX-License-Identifier: Apache-2.0
"""Rosbag2 reader."""
from __future__ import annotations
import sqlite3
from contextlib import contextmanager
from pathlib import Path
from tempfile import TemporaryDirectory
from typing import TYPE_CHECKING
import zstandard
from ruamel.yaml import YAML
from ruamel.yaml.error import YAMLError
from rosbags.interfaces import Connection, ConnectionExtRosbag2
if TYPE_CHECKING:
from types import TracebackType
from typing import Any, Generator, Iterable, Literal, Optional, Type, TypedDict, Union
class StartingTime(TypedDict):
"""Bag starting time."""
nanoseconds_since_epoch: int
class Duration(TypedDict):
"""Bag starting time."""
nanoseconds: int
class TopicMetadata(TypedDict):
"""Topic metadata."""
name: str
type: str
serialization_format: str
offered_qos_profiles: str
class TopicWithMessageCount(TypedDict):
"""Topic with message count."""
message_count: int
topic_metadata: TopicMetadata
class Metadata(TypedDict):
"""Rosbag2 metadata file."""
version: int
storage_identifier: str
relative_file_paths: list[str]
starting_time: StartingTime
duration: Duration
message_count: int
compression_format: str
compression_mode: str
topics_with_message_count: list[TopicWithMessageCount]
class ReaderError(Exception):
"""Reader Error."""
@contextmanager
def decompress(path: Path, do_decompress: bool) -> Generator[Path, None, None]:
"""Transparent rosbag2 database decompression context.
This context manager will yield a path to the decompressed file contents.
Args:
path: Potentially compressed file.
do_decompress: Flag indicating if decompression shall occur.
Yields:
Path of transparently decompressed file.
"""
if do_decompress:
decomp = zstandard.ZstdDecompressor()
with TemporaryDirectory() as tempdir:
dbfile = Path(tempdir, path.stem)
with path.open('rb') as infile, dbfile.open('wb') as outfile:
decomp.copy_stream(infile, outfile)
yield dbfile
else:
yield path
class Reader:
"""Reader for rosbag2 files.
It implements all necessary features to access metadata and message
streams.
Version history:
- Version 1: Initial format.
- Version 2: Changed field sizes in C++ implementation.
- Version 3: Added compression.
- Version 4: Added QoS metadata to topics, changed relative file paths
"""
def __init__(self, path: Union[Path, str]):
"""Open rosbag and check metadata.
Args:
path: Filesystem path to bag.
Raises:
ReaderError: Bag not readable or bag metadata.
"""
path = Path(path)
yamlpath = path / 'metadata.yaml'
self.path = path
self.bio = False
try:
yaml = YAML(typ='safe')
dct = yaml.load(yamlpath.read_text())
except OSError as err:
raise ReaderError(f'Could not read metadata at {yamlpath}: {err}.') from None
except YAMLError as exc:
raise ReaderError(f'Could not load YAML from {yamlpath}: {exc}') from None
try:
self.metadata: Metadata = dct['rosbag2_bagfile_information']
if (ver := self.metadata['version']) > 4:
raise ReaderError(f'Rosbag2 version {ver} not supported; please report issue.')
if storageid := self.metadata['storage_identifier'] != 'sqlite3':
raise ReaderError(
f'Storage plugin {storageid!r} not supported; please report issue.',
)
self.paths = [path / Path(x).name for x in self.metadata['relative_file_paths']]
if missing := [x for x in self.paths if not x.exists()]:
raise ReaderError(f'Some database files are missing: {[str(x) for x in missing]!r}')
self.connections = {
idx + 1: Connection(
id=idx + 1,
topic=x['topic_metadata']['name'],
msgtype=x['topic_metadata']['type'],
msgdef='',
md5sum='',
msgcount=x['message_count'],
ext=ConnectionExtRosbag2(
serialization_format=x['topic_metadata']['serialization_format'],
offered_qos_profiles=x['topic_metadata'].get('offered_qos_profiles', ''),
),
) for idx, x in enumerate(self.metadata['topics_with_message_count'])
}
noncdr = {
fmt for x in self.connections.values() if isinstance(x.ext, ConnectionExtRosbag2)
if (fmt := x.ext.serialization_format) != 'cdr'
}
if noncdr:
raise ReaderError(f'Serialization format {noncdr!r} is not supported.')
if self.compression_mode and (cfmt := self.compression_format) != 'zstd':
raise ReaderError(f'Compression format {cfmt!r} is not supported.')
except KeyError as exc:
raise ReaderError(f'A metadata key is missing {exc!r}.') from None
def open(self) -> None:
"""Open rosbag2."""
# Future storage formats will require file handles.
self.bio = True
def close(self) -> None:
"""Close rosbag2."""
# Future storage formats will require file handles.
assert self.bio
self.bio = False
@property
def duration(self) -> int:
"""Duration in nanoseconds between earliest and latest messages."""
nsecs: int = self.metadata['duration']['nanoseconds']
return nsecs + 1
@property
def start_time(self) -> int:
"""Timestamp in nanoseconds of the earliest message."""
return self.metadata['starting_time']['nanoseconds_since_epoch']
@property
def end_time(self) -> int:
"""Timestamp in nanoseconds after the latest message."""
return self.start_time + self.duration
@property
def message_count(self) -> int:
"""Total message count."""
return self.metadata['message_count']
@property
def compression_format(self) -> Optional[str]:
"""Compression format."""
return self.metadata.get('compression_format', None) or None
@property
def compression_mode(self) -> Optional[str]:
"""Compression mode."""
mode = self.metadata.get('compression_mode', '').lower()
return mode if mode != 'none' else None
@property
def topics(self) -> dict[str, Connection]:
"""Topic information.
For the moment this a dictionary mapping topic names to connections.
"""
return {x.topic: x for x in self.connections.values()}
def messages( # pylint: disable=too-many-locals
self,
connections: Iterable[Connection] = (),
start: Optional[int] = None,
stop: Optional[int] = None,
) -> Generator[tuple[Connection, int, bytes], None, None]:
"""Read messages from bag.
Args:
connections: Iterable with connections to filter for. An empty
iterable disables filtering on connections.
start: Yield only messages at or after this timestamp (ns).
stop: Yield only messages before this timestamp (ns).
Yields:
tuples of connection, timestamp (ns), and rawdata.
Raises:
ReaderError: Bag not open.
"""
if not self.bio:
raise ReaderError('Rosbag is not open.')
query = [
'SELECT topics.id,messages.timestamp,messages.data',
'FROM messages JOIN topics ON messages.topic_id=topics.id',
]
args: list[Any] = []
clause = 'WHERE'
if connections:
topics = {x.topic for x in connections}
query.append(f'{clause} topics.name IN ({",".join("?" for _ in topics)})')
args += topics
clause = 'AND'
if start is not None:
query.append(f'{clause} messages.timestamp >= ?')
args.append(start)
clause = 'AND'
if stop is not None:
query.append(f'{clause} messages.timestamp < ?')
args.append(stop)
clause = 'AND'
query.append('ORDER BY timestamp')
querystr = ' '.join(query)
for filepath in self.paths:
with decompress(filepath, self.compression_mode == 'file') as path:
conn = sqlite3.connect(f'file:{path}?immutable=1', uri=True)
conn.row_factory = lambda _, x: x
cur = conn.cursor()
cur.execute(
'SELECT count(*) FROM sqlite_master '
'WHERE type="table" AND name IN ("messages", "topics")',
)
if cur.fetchone()[0] != 2:
raise ReaderError(f'Cannot open database {path} or database missing tables.')
cur.execute('SELECT name,id FROM topics')
connmap: dict[int, Connection] = {
row[1]: next((x for x in self.connections.values() if x.topic == row[0]),
None) # type: ignore
for row in cur
}
cur.execute(querystr, args)
if self.compression_mode == 'message':
decomp = zstandard.ZstdDecompressor().decompress
for row in cur:
cid, timestamp, data = row
yield connmap[cid], timestamp, decomp(data)
else:
for cid, timestamp, data in cur:
yield connmap[cid], timestamp, data
def __enter__(self) -> Reader:
"""Open rosbag2 when entering contextmanager."""
self.open()
return self
def __exit__(
self,
exc_type: Optional[Type[BaseException]],
exc_val: Optional[BaseException],
exc_tb: Optional[TracebackType],
) -> Literal[False]:
"""Close rosbag2 when exiting contextmanager."""
self.close()
return False