python-oxlib/oxlib/cache.py

137 lines
4.5 KiB
Python

# -*- coding: utf-8 -*-
# vi:si:et:sw=4:sts=4:ts=4
# GPL 2008
import gzip
import hashlib
import os
import StringIO
import time
import urlparse
import urllib2
import chardet
import simplejson
import net
from net import DEFAULT_HEADERS, getEncoding
cache_timeout = 30*24*60*60 # default is 30 days
def status(url, data=None, headers=DEFAULT_HEADERS, timeout=cache_timeout):
'''
>>> status('http://google.com')
200
>>> status('http://google.com/mysearch')
404
'''
headers = getHeaders(url, data, headers)
return int(headers['status'])
def exists(url, data=None, headers=DEFAULT_HEADERS, timeout=cache_timeout):
'''
>>> exists('http://google.com')
True
>>> exists('http://google.com/mysearch')
False
'''
s = status(url, data, headers, timeout)
if s >= 200 and s < 400:
return True
return False
def getHeaders(url, data=None, headers=DEFAULT_HEADERS, timeout=cache_timeout):
url_cache_file = "%s.headers" % _getUrlCacheFile(url, data, headers)
url_headers = _loadUrlCache(url_cache_file, timeout)
if url_headers:
url_headers = simplejson.loads(url_headers)
else:
url_headers = net.getHeaders(url, data, headers)
_saveUrlHeaders(url_cache_file, url_headers)
return url_headers
class InvalidResult(Exception):
"""Base class for exceptions in this module."""
def __init__(self, result, headers):
self.result = result
self.headers = headers
def getUrl(url, data=None, headers=DEFAULT_HEADERS, timeout=cache_timeout, valid=None):
'''
url - url to load
data - possible post data
headers - headers to send with request
timeout - get from cache if cache not older than given seconds, -1 to get from cache
valid - function to check if result is ok, its passed result and headers
if this function fails, InvalidResult will be raised deal with it in your code
'''
#FIXME: send last-modified / etag from cache and only update if needed
if isinstance(url, unicode):
url = url.encode('utf-8')
url_cache_file = _getUrlCacheFile(url, data, headers)
result = _loadUrlCache(url_cache_file, timeout)
if not result:
try:
url_headers, result = net.getUrl(url, data, headers, returnHeaders=True)
except urllib2.HTTPError, e:
e.headers['Status'] = "%s" % e.code
url_headers = dict(e.headers)
result = e.read()
if url_headers.get('content-encoding', None) == 'gzip':
result = gzip.GzipFile(fileobj=StringIO.StringIO(result)).read()
if not valid or valid(result, url_headers):
_saveUrlCache(url_cache_file, result, url_headers)
else:
raise InvalidResult(result, url_headers)
return result
def getUrlUnicode(url, data=None, headers=DEFAULT_HEADERS, timeout=cache_timeout, _getUrl=getUrl, valid=None):
data = _getUrl(url, data, headers, timeout, valid)
encoding = getEncoding(data)
if not encoding:
encoding = 'latin-1'
return unicode(data, encoding)
def _getCacheBase():
'cache base is eather ~/.ox/cache or can set via env variable oxCACHE'
return os.environ.get('oxCACHE', os.path.expanduser('~/.ox/cache'))
def _getUrlCacheFile(url, data=None, headers=DEFAULT_HEADERS):
if data:
url_hash = hashlib.sha1(url + '?' + data).hexdigest()
else:
url_hash = hashlib.sha1(url).hexdigest()
domain = ".".join(urlparse.urlparse(url)[1].split('.')[-2:])
return os.path.join(_getCacheBase(), domain, url_hash[:2], url_hash[2:4], url_hash[4:6], url_hash)
def _loadUrlCache(url_cache_file, timeout=cache_timeout):
if timeout == 0:
return None
if os.path.exists(url_cache_file):
ctime = os.stat(url_cache_file).st_ctime
now = time.mktime(time.localtime())
file_age = now-ctime
if timeout < 0 or file_age < timeout:
f = open(url_cache_file)
data = f.read()
f.close()
return data
return None
def _saveUrlCache(url_cache_file, data, headers):
folder = os.path.dirname(url_cache_file)
if not os.path.exists(folder):
os.makedirs(folder)
f = open(url_cache_file, 'w')
f.write(data)
f.close()
_saveUrlHeaders("%s.headers" % url_cache_file, headers)
def _saveUrlHeaders(url_cache_file, headers):
folder = os.path.dirname(url_cache_file)
if not os.path.exists(folder):
os.makedirs(folder)
f = open(url_cache_file, 'w')
f.write(simplejson.dumps(headers))
f.close()