65 lines
2.8 KiB
Python
65 lines
2.8 KiB
Python
from django.core.cache import cache
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from django.utils.httpwrappers import HttpResponseNotModified
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import cStringIO, datetime, gzip, md5
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# From http://www.xhaus.com/alan/python/httpcomp.html#gzip
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# Used with permission.
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def compress_string(s):
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zbuf = cStringIO.StringIO()
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zfile = gzip.GzipFile(mode='wb', compresslevel=6, fileobj=zbuf)
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zfile.write(s)
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zfile.close()
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return zbuf.getvalue()
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def cache_page(view_func, cache_timeout, key_prefix=''):
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"""
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Decorator for views that tries getting the page from the cache and
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populates the cache if the page isn't in the cache yet. Also takes care
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of ETags and gzips the page if the client supports it.
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The cache is keyed off of the page's URL plus the optional key_prefix
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variable. Use key_prefix if your Django setup has multiple sites that
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use cache; otherwise the cache for one site would affect the other. A good
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example of key_prefix is to use sites.get_current().domain, because that's
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unique across all CMS instances on a particular server.
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"""
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def _check_cache(request, *args, **kwargs):
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try:
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accept_encoding = request.META['HTTP_ACCEPT_ENCODING']
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except KeyError:
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accept_encoding = ''
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accepts_gzip = 'gzip' in accept_encoding
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cache_key = 'views.decorators.cache.cache_page.%s.%s.%s' % (key_prefix, request.path, accepts_gzip)
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response = cache.get(cache_key, None)
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if response is None:
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response = view_func(request, *args, **kwargs)
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content = response.get_content_as_string('utf-8')
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if accepts_gzip:
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content = compress_string(content)
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response.content = content
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response['Content-Encoding'] = 'gzip'
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response['ETag'] = md5.new(content).hexdigest()
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response['Content-Length'] = '%d' % len(content)
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response['Last-Modified'] = datetime.datetime.utcnow().strftime('%a, %d %b %Y %H:%M:%S GMT')
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cache.set(cache_key, response, cache_timeout)
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else:
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# Logic is from http://simon.incutio.com/archive/2003/04/23/conditionalGet
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try:
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if_none_match = request.META['HTTP_IF_NONE_MATCH']
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except KeyError:
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if_none_match = None
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try:
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if_modified_since = request.META['HTTP_IF_MODIFIED_SINCE']
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except KeyError:
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if_modified_since = None
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if if_none_match is None and if_modified_since is None:
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pass
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elif if_none_match is not None and response['ETag'] != if_none_match:
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pass
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elif if_modified_since is not None and response['Last-Modified'] != if_modified_since:
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pass
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else:
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return HttpResponseNotModified()
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return response
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return _check_cache
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