Source code for pymmails.helpers.buffer_files_writing

"""
Buffer files writing


:githublink:`%|py|5`
"""
import io
import os
from pyquickhelper.loghelper import noLOG
from .helpers_exceptions import FileAlreadyExistingException, FileNotFlushedException


[docs]class BufferFilesWriting: """ this class aims at delaying writing files, method *open* returns a buffer, method *flush* actually writes the file :githublink:`%|py|16` """
[docs] def __init__(self, flush_every=20, fLOG=noLOG): """ constructor :param flush_every: flush every 20 created files :githublink:`%|py|23` """ self._nb = 0 self._buffer = {} self._done = set() self.fLOG = fLOG self._flush_every = flush_every
[docs] def exists(self, name, local=True): """ tells if a file was already written :param name: name :param local: check local existence too :return: boolean :githublink:`%|py|37` """ return name in self._done or \ name in self._buffer or \ (local and os.path.exists(name))
[docs] def listfiles(self): """ returns the list of flushed and opened files, does not preserved order :return: list of files :githublink:`%|py|48` """ return list(self._done) + list(self._buffer.keys())
[docs] def __len__(self): """ return the number of buffered files :githublink:`%|py|54` """ return len(self._buffer)
[docs] def open(self, name, text=True, encoding="utf8"): """ open a file and returns a buffer :param name: filename :param text: text or binary file :param encoding: encoding :return: a buffer :githublink:`%|py|65` """ if name is None or name == '': raise ValueError("name cannot be empty.") if len(self._buffer) > self._flush_every: self.flush(None) if name in self._buffer: raise FileAlreadyExistingException(name) if text: buf = io.StringIO() else: buf = io.BytesIO() self._buffer[name] = (buf, encoding, self._nb) self._nb += 1 return buf
[docs] def read_binary_content(self, name, local=True): """ return the content of file (binary format) :param name: name :param local: check local existence too and read the content from it :return: boolean :githublink:`%|py|88` """ if name is None or name == '': raise ValueError("name cannot be empty.") if name in self._buffer: content = self._buffer[name][0].getvalue() if isinstance(content, str): content = bytes(content, self._buffer[name][1]) else: with open(name, "rb") as f: content = f.read() return content
[docs] def flush(self, name, upto=False): """ flush a file (actually write it) and make it disappear from the list of buffered files, if the folder does not exists, the method creates it :param name: file name (or None for all) :param upto: flush all files up to this one :return: number of written bytes :githublink:`%|py|108` """ if name is None: size = 0 keys = list(self._buffer.keys()) for name_ in keys: size += self.flush(name_) return size else: if name not in self._buffer: raise FileNotFoundError( name + "\nEXISTING\n" + "\n".join(self.listfiles())) if upto: n = self._buffer[name][2] names = [name for name, v in self._buffer.items() if v[2] <= n] size = 0 for name_ in names: size += self.flush(name_) return size else: fold = os.path.dirname(name) if fold is None or fold == '': raise RuntimeError( "Folder cannot be empty for file '{0}'".format(name)) if not os.path.exists(fold): os.makedirs(fold) buf = self._buffer[name][0] if isinstance(buf, io.StringIO): b = buf.getvalue() with open(name, "w", encoding=self._buffer[name][1]) as f: f.write(b) else: b = buf.getvalue() with open(name, "wb") as f: f.write(b) self.fLOG( "[BufferFilesWriting.flush] write '{0}'".format(name)) del self._buffer[name] self._done.add(name) return len(b)
[docs] def __del__(self): """ destructor, check everything was flushed :githublink:`%|py|151` """ if len(self._buffer) > 0: raise FileNotFlushedException( "\n".join(sorted(self._buffer.keys())))