[3] | 1 | ''' |
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| 2 | Provides several CacheStore backends for Cheetah's caching framework. The |
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| 3 | methods provided by these classes have the same semantics as those in the |
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| 4 | python-memcached API, except for their return values: |
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| 5 | |
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| 6 | set(key, val, time=0) |
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| 7 | set the value unconditionally |
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| 8 | add(key, val, time=0) |
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| 9 | set only if the server doesn't already have this key |
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| 10 | replace(key, val, time=0) |
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| 11 | set only if the server already have this key |
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| 12 | get(key, val) |
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| 13 | returns val or raises a KeyError |
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| 14 | delete(key) |
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| 15 | deletes or raises a KeyError |
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| 16 | ''' |
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| 17 | import time |
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| 18 | |
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| 19 | from Cheetah.Utils.memcache import Client as MemcachedClient |
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| 20 | |
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| 21 | class Error(Exception): |
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| 22 | pass |
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| 23 | |
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| 24 | class AbstractCacheStore(object): |
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| 25 | |
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| 26 | def set(self, key, val, time=None): |
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| 27 | raise NotImplementedError |
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| 28 | |
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| 29 | def add(self, key, val, time=None): |
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| 30 | raise NotImplementedError |
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| 31 | |
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| 32 | def replace(self, key, val, time=None): |
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| 33 | raise NotImplementedError |
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| 34 | |
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| 35 | def delete(self, key): |
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| 36 | raise NotImplementedError |
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| 37 | |
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| 38 | def get(self, key): |
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| 39 | raise NotImplementedError |
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| 40 | |
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| 41 | class MemoryCacheStore(AbstractCacheStore): |
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| 42 | def __init__(self): |
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| 43 | self._data = {} |
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| 44 | |
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| 45 | def set(self, key, val, time=0): |
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| 46 | self._data[key] = (val, time) |
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| 47 | |
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| 48 | def add(self, key, val, time=0): |
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| 49 | if self._data.has_key(key): |
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| 50 | raise Error('a value for key %r is already in the cache'%key) |
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| 51 | self._data[key] = (val, time) |
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| 52 | |
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| 53 | def replace(self, key, val, time=0): |
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| 54 | if self._data.has_key(key): |
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| 55 | raise Error('a value for key %r is already in the cache'%key) |
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| 56 | self._data[key] = (val, time) |
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| 57 | |
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| 58 | def delete(self, key): |
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| 59 | del self._data[key] |
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| 60 | |
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| 61 | def get(self, key): |
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| 62 | (val, exptime) = self._data[key] |
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| 63 | if exptime and time.time() > exptime: |
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| 64 | del self._data[key] |
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| 65 | raise KeyError(key) |
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| 66 | else: |
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| 67 | return val |
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| 68 | |
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| 69 | def clear(self): |
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| 70 | self._data.clear() |
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| 71 | |
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| 72 | class MemcachedCacheStore(AbstractCacheStore): |
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| 73 | servers = ('127.0.0.1:11211') |
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| 74 | def __init__(self, servers=None, debug=False): |
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| 75 | if servers is None: |
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| 76 | servers = self.servers |
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| 77 | |
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| 78 | self._client = MemcachedClient(servers, debug) |
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| 79 | |
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| 80 | def set(self, key, val, time=0): |
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| 81 | self._client.set(key, val, time) |
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| 82 | |
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| 83 | def add(self, key, val, time=0): |
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| 84 | res = self._client.add(key, val, time) |
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| 85 | if not res: |
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| 86 | raise Error('a value for key %r is already in the cache'%key) |
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| 87 | self._data[key] = (val, time) |
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| 88 | |
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| 89 | def replace(self, key, val, time=0): |
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| 90 | res = self._client.replace(key, val, time) |
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| 91 | if not res: |
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| 92 | raise Error('a value for key %r is already in the cache'%key) |
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| 93 | self._data[key] = (val, time) |
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| 94 | |
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| 95 | def delete(self, key): |
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| 96 | res = self._client.delete(key, time=0) |
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| 97 | if not res: |
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| 98 | raise KeyError(key) |
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| 99 | |
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| 100 | def get(self, key): |
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| 101 | val = self._client.get(key) |
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| 102 | if val is None: |
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| 103 | raise KeyError(key) |
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| 104 | else: |
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| 105 | return val |
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| 106 | |
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| 107 | def clear(self): |
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| 108 | self._client.flush_all() |
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