Ruby » Ruby master

Bug #19621

Updated by felix.wolfsteller@betterplace.org (Felix Wolfsteller) over 1 year ago

By default on unixoid systems, default, `Resolv` will read `/etc/hosts` once. Privacy- and security aware people might use the file to prevent unwanted traffic, developers use it to quickly manipulate address resolution. 

 `Resolv::Hosts` uses [`IO.read`](https://github.com/betterplace/ruby/blob/9b07d30df8c6bf65c2558c023fd6452405915610/lib/resolv.rb#LL195C4-L195C4), which seems to be inefficient when dealing with large amounts of data that should be consumed by line. 

 E.g. if you install the `/etc/hosts` additions by [hblock](https://hblock.molinero.dev/hosts) (https://github.com/hectorm/hblock), the first call to resolve an address will likely take **minutes**. 

 We believe the solution is easy: Use streaming `IO.foreach` (see patch and PR attached). 

 Benchmarking with examplary /etc/host from xyz done like this 

 ``` 
 require 'resolv' 
 require 'benchmark' 

 Benchmark.measure do 
   Resolv::Hosts.new.lazy_initialize 
 end 
 ``` 

 With `read`: 
 ... 

 With `foreach`: 
 ... 

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