Edit File: SmartIO.py
# # Smart IO class # # Copyright (c) 2002--2016 Red Hat, Inc. # # Author: Mihai Ibanescu <misa@redhat.com> """ This module implements the SmartIO class """ import os try: # python2 from cStringIO import StringIO except ImportError: # python3 from io import BytesIO as StringIO class SmartIO: """ The SmartIO class allows one to put a cap on the memory consumption. StringIO objects are very fast, because they are stored in memory, but if they are too big the memory footprint becomes noticeable. The write method of a SmartIO determines if the data that is to be added to the (initially) StrintIO object does not exceed a certain threshold; if it does, it switches the storage to a temporary disk file """ def __init__(self, max_mem_size=16384, force_mem=0): self._max_mem_size = max_mem_size self._io = StringIO() # self._fixed is a flag to show if we're supposed to consider moving # the StringIO object into a tempfile # Invariant: if self._fixed == 0, we have a StringIO (if self._fixed # is 1 and force_mem was 0, then we have a file) if force_mem: self._fixed = 1 else: self._fixed = 0 def set_max_mem_size(self, max_mem_size): self._max_mem_size = max_mem_size def get_max_mem_size(self): return self._max_mem_size def write(self, data): if not self._fixed: # let's consider moving it to a file if len(data) + self._io.tell() > self._max_mem_size: # We'll overflow, change to a tempfile tmpfile = _tempfile() tmpfile.write(self._io.getvalue()) self._fixed = 1 self._io = tmpfile self._io.write(data) def __getattr__(self, name): return getattr(self._io, name) # Creates a temporary file and passes back its file descriptor def _tempfile(): import tempfile (fd, fname) = tempfile.mkstemp(prefix="_rhn_transports-%d-" \ % os.getpid()) # tempfile, unlink it os.unlink(fname) return os.fdopen(fd, "wb+")
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