213 lines
7.1 KiB
Python
213 lines
7.1 KiB
Python
import uuid
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import io
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import os
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import datetime
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import copy
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import logging
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class StreamObject(object):
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def __init__(self, write_to_file: bool=None, filename: str=None, folder: str=None, fmt: str='file') -> None:
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# Store a nice ID
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self.id = uuid.uuid4().hex
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logging.info("Created {}".format(self.id))
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# Create file name
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iterator = 0
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f_name = self.build_file_path(filename, folder, fmt)
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while os.path.isfile(f_name): # While file already exists
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iterator += 1 # Add a file name iterator
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f_name = self.build_file_path(filename, folder, fmt, iterator=iterator) # Rebuild file name
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self.file = f_name
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# Byte stream properties
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self.stream = io.BytesIO() # Byte stream that data will be written to
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# Set default write target
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self.write_to_file = write_to_file
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if self.write_to_file is False:
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logging.debug("Default target for {} set to 'stream'".format(self.id))
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self.target = self.stream
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else:
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logging.debug("Default target for {} set to 'file'".format(self.id))
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self.target = self.file
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# Keep on disk after close by default
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self.keep_on_disk = True
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# Log if created by context manager
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self.context_manager = False
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# Object lock
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self.locked = False # Is the StreamObject locked for writing? (Handled by StreamingCamera)
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def __enter__(self):
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logging.debug("Entering context for {}.\
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Stored files will be cleaned up automatically.".format(self.id))
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self.keep_on_disk = False # Flag file to be removed on close.
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self.context_manager = True # Used in metadata
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return self
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def __exit__(self, *args):
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logging.info("Cleaning up {}".format(self.id))
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self.close()
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def build_file_path(self, filename: str, folder: str, fmt: str, iterator: int=0) -> str:
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"""
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Construct a full file path, based on filename, folder, and file format.
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Defaults to datestamp. Iterator adds a numeric increment to the file name.
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"""
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if filename:
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file_name = "{}.{}".format(filename, fmt)
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else:
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file_name_base = datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
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if iterator:
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file_name_base = "{}_{}".format(file_name_base, iterator)
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file_name = "{}.{}".format(file_name_base, fmt)
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# Create folder and file
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if folder:
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if not os.path.exists(folder):
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os.mkdir(folder)
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file_path = os.path.join(folder, file_name)
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else:
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file_path = file_name
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return file_path
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def lock(self):
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"""Set locked flag to True."""
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self.locked = True
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def unlock(self):
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"""Set locked flag to False."""
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self.locked = False
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@property
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def stream_exists(self, auto_rewind=True) -> bool:
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"""Check if BytesIO stream is empty"""
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if auto_rewind:
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self.stream.seek(0) # Rewind the data bytes for reading
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if self.stream.getvalue(): # If data stream contains data
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self.stream.seek(0) # Rewind the data bytes for reading
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return True
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else:
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self.stream.seek(0) # Rewind the data bytes for reading
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return False
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@property
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def file_exists(self) -> bool:
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"""Check if corresponding file exists"""
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if os.path.isfile(self.file):
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return True
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else:
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return False
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@property
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def metadata(self) -> dict:
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d = {
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'id': self.id,
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'locked': self.locked,
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'keep_on_disk': self.keep_on_disk,
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'path': self.file,
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'context_manager': self.context_manager,
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}
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# Get file path
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if self.file_exists:
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d['file'] = self.file
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else:
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d['file'] = None
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# Check stream
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if self.stream_exists:
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d['stream'] = True
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else:
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d['stream'] = False
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# Check if file was manually deleted
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if self.keep_on_disk and not self.file_exists:
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d['path'] = "{} (Deleted)".format(d['path'])
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return d
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@property
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def data(self) -> io.BytesIO:
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"""Return a byte string of the capture data."""
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self.stream.seek(0) # Rewind the data bytes for reading
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if self.stream_exists: # If data stream contains data
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data = io.BytesIO(self.stream.getbuffer()) # Create a copy of the stream bytes
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else: # If data stream is empty
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if self.file_exists: # If data file exists
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# TODO: Streamline this bit
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logging.info("No stream data. Opening from file {}".format(self.file))
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with open(self.file, 'rb') as f:
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d = io.BytesIO(f.read()) # Load bytes from file in disk
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d.seek(0) # Rewind loaded stream
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data = io.BytesIO(d.getbuffer()) # Create a copy of the stream bytes
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else:
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data = None
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return data # Read and return bytes data
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@property
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def binary(self) -> bytes:
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"""Return a byte string of the capture data."""
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return self.data.getvalue()
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def load_file(self) -> bool:
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"""Load data stored on disk to the in-memory stream."""
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if self.file_exists: # If data file exists
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# TODO: Streamline this bit
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with open(self.file, 'rb') as f:
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self.stream = io.BytesIO(f.read()) # Load bytes from file in disk
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self.stream.seek(0) # Rewind data bytes again
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return True
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else:
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return False
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def save_file(self) -> bool:
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"""
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Write the StreamObjects stream to a file.
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"""
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if self.stream_exists: # If there's a stream to save
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with open(self.file, 'ab') as f: # Load file as bytes
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logging.debug("Writing stream to file {}".format(self.file))
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f.seek(0, 0) # Seek to the start of the file
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f.write(self.binary) # Write data bytes to file
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return True
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else:
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return False
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def delete_stream(self):
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"""Clears the BytesIO stream of the StreamObject."""
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self.stream = io.BytesIO()
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def delete_file(self) -> bool:
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"""
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If the StreamObject has been saved to disk, deletes the file and returns True.
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"""
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if os.path.isfile(self.file):
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logging.info("Deleting file {}".format(self.file))
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os.remove(self.file)
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return True
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else:
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return False
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def shunt(self):
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"""Demote the StreamObject from being stored in memory."""
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if not self.file_exists: # If file doesn't already exist
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self.save_file() # Save stream to disk, if it exists
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self.delete_stream() # Delete the stream from memory
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def close(self):
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"""Both clear the stream, and delete any associated on-disk data"""
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logging.info("Closing {}".format(self.id))
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self.delete_stream()
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if not self.keep_on_disk:
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self.delete_file()
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