def _fetch_from_cache(self):
"""Attempt to fetch a file from cache or return None.
Returns:
*iter of open, decompressed file pointer from cache or None.
"""
if CACHE_DIR is None:
raise Exception, "Set environ var CACHE_DIR to cache directory."
filepath = os.path.join(CACHE_DIR, self.cache_name)
if os.path.exists(filepath):
return gzip.open(filepath, "rb")
else:
return None
def __init__(self, fp, size=None, cache=None, report=True, finalize=True, ftp=False):
"""Initialize self.
Args:
fp: open file pointer like object like HTTP connection
size: int of expected bytes in download or None if unknown
cache: str of cache file name or None if cache is disabled
report: bool to report download status
finalize: bool if close() is called before self.completed, finish
downloading before closing buffer and any cache
"""
self.buffer = fp
self.cache = cache
self.size = size
if self.size:
# Convert to float to avoid integer division complications.
self.size = float(self.size)
self.report = report
self.finalize = finalize
self.bytes_read = 0
self.bytes_reported = 0
self.fp_out = None
self.completed = False
self.tmp_filepath = None
self.dest_filepath = None
self.closed = False
if cache:
# Finalized (completely downloaded) cache filename
global CACHE_DIR
if CACHE_DIR is None:
# try to get cache directory from settings in runtime
if "CACHE_DIR" in os.environ:
CACHE_DIR = os.environ["CACHE_DIR"]
if CACHE_DIR is None:
raise Exception, "Set environ variable CACHE_DIR to a system path that this program can use as a cache directory. For example: `export CACHE_DIR=/home/z/Desktop` or in Python, `os.environ['CACHE_DIR'] = '/my/path'`"
self.dest_filepath = os.path.join(CACHE_DIR, cache)
# Add ".tmp" to end of cache filename to indicate cache is incomplete.
self.tmp_filepath = self.dest_filepath + ".tmp"
# Cache files are compressed (even if the underlying data is compressed)
self.fp_out = gzip.open(self.tmp_filepath, "wb")
