README.md 7.5KB
cacheable-lookup
A cacheable
dns.lookup(…)that respects TTL :tada:
Making lots of HTTP requests? You can save some time by caching DNS lookups :zap:
Usage
Using the lookup option
const http = require('http');
const CacheableLookup = require('cacheable-lookup');
const cacheable = new CacheableLookup();
http.get('http://example.com', {lookup: cacheable.lookup}, response => {
// Handle the response here
});
Attaching CacheableLookup to an Agent
const http = require('http');
const CacheableLookup = require('cacheable-lookup');
const cacheable = new CacheableLookup();
cacheable.install(http.globalAgent);
http.get('http://example.com', response => {
// Handle the response here
});
API
new CacheableLookup(options)
Returns a new instance of CacheableLookup.
options
Type: object
Default: {}
Options used to cache the DNS lookups.
cache
Type: Map | Keyv
Default: new Map()
Custom cache instance. If undefined, it will create a new one.
Note: If you decide to use Keyv instead of the native implementation, the performance will drop by 10x. Memory leaks may occur as it doesn’t provide any way to remove all the deprecated values at once.
Tip: QuickLRU is fully compatible with the Map API, you can use it to limit the amount of cached entries. Example:
const http = require('http');
const CacheableLookup = require('cacheable-lookup');
const QuickLRU = require('quick-lru');
const cacheable = new CacheableLookup({
cache: new QuickLRU({maxSize: 1000})
});
http.get('http://example.com', {lookup: cacheable.lookup}, response => {
// Handle the response here
});
options.maxTtl
Type: number
Default: Infinity
The maximum lifetime of the entries received from the specifed DNS server (TTL in seconds).
If set to 0, it will make a new DNS query each time.
Pro Tip: This shouldn’t be lower than your DNS server response time in order to prevent bottlenecks. For example, if you use Cloudflare, this value should be greater than 0.01.
options.fallbackDuration
Type: number
Default: 3600 (1 hour)
When the DNS server responds with ENOTFOUND or ENODATA and the OS reports that the entry is available, it will use dns.lookup(...) directly for the requested hostnames for the specified amount of time (in seconds).
If you don’t query internal hostnames (such as localhost, database.local etc.), it is strongly recommended to set this value to 0.
options.errorTtl
Type: number
Default: 0.15
The time how long it needs to remember queries that threw ENOTFOUND or ENODATA (TTL in seconds).
Note: This option is independent, options.maxTtl does not affect this.
Pro Tip: This shouldn’t be lower than your DNS server response time in order to prevent bottlenecks. For example, if you use Cloudflare, this value should be greater than 0.01.
options.resolver
Type: dns.Resolver | dns.promises.Resolver
Default: new dns.promises.Resolver()
An instance of DNS Resolver used to make DNS queries.
options.lookup
Type: Function
Default: dns.lookup
The fallback function to use when the DNS server responds with ENOTFOUND or ENODATA.
Note: This has no effect if the fallbackDuration option is less than 1.
Entry object
Type: object
address
Type: string
The IP address (can be an IPv4 or IPv6 address).
family
Type: number
The IP family (4 or 6).
expires
Type: number
Note: This is not present when falling back to dns.lookup(...)!
The timestamp (Date.now() + ttl * 1000) when the entry expires.
ttl
Note: This is not present when falling back to dns.lookup(...)!
The time in seconds for its lifetime.
Entry object (callback-style)
When options.all is false, then callback(error, address, family, expires, ttl) is called.
When options.all is true, then callback(error, entries) is called.
CacheableLookup instance
servers
Type: Array
The DNS servers used to make queries. Can be overridden - doing so will clear the cache.
lookup(hostname, options, callback)
lookupAsync(hostname, options)
The asynchronous version of dns.lookup(…).
Returns an entry object.
If options.all is true, returns an array of entry objects.
hostname
Type: string
options
Type: object
The same as the dns.lookup(…) options.
query(hostname)
An asynchronous function which returns cached DNS lookup entries.
This is the base for lookupAsync(hostname, options) and lookup(hostname, options, callback).
Note: This function has no options.
Returns an array of objects with address, family, ttl and expires properties.
queryAndCache(hostname)
An asynchronous function which makes two DNS queries: A and AAAA. The result is cached.
This is used by query(hostname) if no entry in the database is present.
Returns an array of objects with address, family, ttl and expires properties.
updateInterfaceInfo()
Updates interface info. For example, you need to run this when you plug or unplug your WiFi driver.
Note: Running updateInterfaceInfo() will trigger clear() only on network interface removal.
clear(hostname?)
Clears the cache for the given hostname. If the hostname argument is not present, the entire cache will be emptied.
High performance
Performed on:
- Query:
example.com - CPU: i7-7700k
- CPU governor: performance
CacheableLookup#lookupAsync x 2,896,251 ops/sec ±1.07% (85 runs sampled)
CacheableLookup#lookupAsync.all x 2,842,664 ops/sec ±1.11% (88 runs sampled)
CacheableLookup#lookupAsync.all.ADDRCONFIG x 2,598,283 ops/sec ±1.21% (88 runs sampled)
CacheableLookup#lookup x 2,565,913 ops/sec ±1.56% (85 runs sampled)
CacheableLookup#lookup.all x 2,609,039 ops/sec ±1.01% (86 runs sampled)
CacheableLookup#lookup.all.ADDRCONFIG x 2,416,242 ops/sec ±0.89% (85 runs sampled)
dns#lookup x 7,272 ops/sec ±0.36% (86 runs sampled)
dns#lookup.all x 7,249 ops/sec ±0.40% (86 runs sampled)
dns#lookup.all.ADDRCONFIG x 5,693 ops/sec ±0.28% (85 runs sampled)
Fastest is CacheableLookup#lookupAsync.all
Related
- cacheable-request - Wrap native HTTP requests with RFC compliant cache support
License
MIT