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Viewing changes to vendor/Twisted-10.0.0/twisted/names/cache.py

  • Committer: Jesse Andrews
  • Date: 2010-05-28 06:05:26 UTC
  • Revision ID: git-v1:bf6e6e718cdc7488e2da87b21e258ccc065fe499
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vendor/Twisted-10.0.0/twisted/names/cache.py
 
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# -*- test-case-name: twisted.names.test -*-
 
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# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
 
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# See LICENSE for details.
 
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import time
 
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from zope.interface import implements
 
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from twisted.names import dns
 
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from twisted.python import failure, log
 
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from twisted.internet import interfaces, defer
 
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import common
 
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class CacheResolver(common.ResolverBase):
 
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    """A resolver that serves records from a local, memory cache."""
 
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    implements(interfaces.IResolver)
 
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    cache = None
 
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    def __init__(self, cache = None, verbose = 0):
 
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        common.ResolverBase.__init__(self)
 
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        if cache is None:
 
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            cache = {}
 
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        self.cache = cache
 
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        self.verbose = verbose
 
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        self.cancel = {}
 
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    def __setstate__(self, state):
 
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        self.__dict__ = state
 
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        now = time.time()
 
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        for (k, (when, (ans, add, ns))) in self.cache.items():
 
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            diff = now - when
 
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            for rec in ans + add + ns:
 
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                if rec.ttl < diff:
 
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                    del self.cache[k]
 
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                    break
 
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    def __getstate__(self):
 
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        for c in self.cancel.values():
 
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            c.cancel()
 
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        self.cancel.clear()
 
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        return self.__dict__
 
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    def _lookup(self, name, cls, type, timeout):
 
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        now = time.time()
 
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        q = dns.Query(name, type, cls)
 
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        try:
 
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            when, (ans, auth, add) = self.cache[q]
 
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        except KeyError:
 
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            if self.verbose > 1:
 
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                log.msg('Cache miss for ' + repr(name))
 
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            return defer.fail(failure.Failure(dns.DomainError(name)))
 
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        else:
 
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            if self.verbose:
 
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                log.msg('Cache hit for ' + repr(name))
 
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            diff = now - when
 
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            return defer.succeed((
 
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                [dns.RRHeader(str(r.name), r.type, r.cls, r.ttl - diff, r.payload) for r in ans],
 
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                [dns.RRHeader(str(r.name), r.type, r.cls, r.ttl - diff, r.payload) for r in auth],
 
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                [dns.RRHeader(str(r.name), r.type, r.cls, r.ttl - diff, r.payload) for r in add]
 
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            ))
 
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    def lookupAllRecords(self, name, timeout = None):
 
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        return defer.fail(failure.Failure(dns.DomainError(name)))
 
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    def cacheResult(self, query, payload):
 
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        if self.verbose > 1:
 
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            log.msg('Adding %r to cache' % query)
 
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        self.cache[query] = (time.time(), payload)
 
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        if self.cancel.has_key(query):
 
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            self.cancel[query].cancel()
 
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        s = list(payload[0]) + list(payload[1]) + list(payload[2])
 
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        m = s[0].ttl
 
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        for r in s:
 
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            m = min(m, r.ttl)
 
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        from twisted.internet import reactor
 
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        self.cancel[query] = reactor.callLater(m, self.clearEntry, query)
 
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    def clearEntry(self, query):
 
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        del self.cache[query]
 
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        del self.cancel[query]