Resolver Caching Classes — dnspython 2.8.0 documentation (original) (raw)
The dnspython resolver does not cache by default, but caching can be enabled by creating a cache and assigning it to the resolver’s _cache_attribute. If a cache has been configured, the resolver caches both positive and negative responses. The cache respects the DNS TTL of the data, and will not return expired entries.
Two thread-safe cache implementations are provided, a simple dictionary-based Cache, and an LRUCache which provides cache size control suitable for use in web crawlers. Both are subclasses of a common base class which provides basic statistics. The LRUCache can also provide a hits count per cache entry.
class dns.resolver.CacheBase[source]
get_statistics_snapshot() → CacheStatistics[source]
Return a consistent snapshot of all the statistics.
If running with multiple threads, it’s better to take a snapshot than to call statistics methods such as hits() and misses() individually.
How many hits has the cache had?
How many misses has the cache had?
reset_statistics() → None[source]
Reset all statistics to zero.
class dns.resolver.Cache(cleaning_interval: float = 300.0)[source]
Simple thread-safe DNS answer cache.
cleaning_interval, a float is the number of seconds between periodic cleanings.
flush(key: Tuple[Name, RdataType, RdataClass] | None = None) → None[source]
Flush the cache.
If key is not None, only that item is flushed. Otherwise the entire cache is flushed.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
get(key: Tuple[Name, RdataType, RdataClass]) → Answer | None[source]
Get the answer associated with key.
Returns None if no answer is cached for the key.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
Returns a dns.resolver.Answer or None.
put(key: Tuple[Name, RdataType, RdataClass], value: Answer) → None[source]
Associate key and value in the cache.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
value, a dns.resolver.Answer, the answer.
class dns.resolver.LRUCache(max_size: int = 100000)[source]
Thread-safe, bounded, least-recently-used DNS answer cache.
This cache is better than the simple cache (above) if you’re running a web crawler or other process that does a lot of resolutions. The LRUCache has a maximum number of nodes, and when it is full, the least-recently used node is removed to make space for a new one.
max_size, an int, is the maximum number of nodes to cache; it must be greater than 0.
flush(key: Tuple[Name, RdataType, RdataClass] | None = None) → None[source]
Flush the cache.
If key is not None, only that item is flushed. Otherwise the entire cache is flushed.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
get(key: Tuple[Name, RdataType, RdataClass]) → Answer | None[source]
Get the answer associated with key.
Returns None if no answer is cached for the key.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
Returns a dns.resolver.Answer or None.
get_hits_for_key(key: Tuple[Name, RdataType, RdataClass]) → int[source]
Return the number of cache hits associated with the specified key.
put(key: Tuple[Name, RdataType, RdataClass], value: Answer) → None[source]
Associate key and value in the cache.
key, a (dns.name.Name, dns.rdatatype.RdataType, dns.rdataclass.RdataClass)tuple whose values are the query name, rdtype, and rdclass respectively.
value, a dns.resolver.Answer, the answer.
class dns.resolver.CacheStatistics(hits: int = 0, misses: int = 0)[source]
Cache Statistics