[ruby-core:84586] [Ruby trunk Feature#14268] [PATCH] net/protocol: optimize large read case

Issue #14268 has been reported by normalperson (Eric Wong).

----------------------------------------
Feature #14268: [PATCH] net/protocol: optimize large read case
https://bugs.ruby-lang.org/issues/14268

* Author: normalperson (Eric Wong)
* Status: Open
* Priority: Normal
* Assignee: naruse (Yui NARUSE)
* Target version: 
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```
Any comment?  Will commit in a few days if none.

net/protocol: optimize large read case

There are several places where rbuf_consume is called with
@rbuf.size as its length arg; simplify that case by avoiding
the slow String#slice! operation in favor of a lightweight
replacement.

The following script exhibits reduced memory usage and
runtimes using the time(1) command:

	2.9s =>  2.6s
	70MB => 12 MB

---------
require 'net/http'
require 'digest/md5'
Thread.abort_on_exception = true
s = TCPServer.new('127.0.0.1', 0)
len = 1024 * 1024 * 1024
th = Thread.new do
  c = s.accept
  c.readpartial(16384)
  c.write("HTTP/1.0 200 OK\r\nContent-Length: #{len}\r\n\r\n")
  IO.copy_stream('/dev/zero', c, len)
  c.close
end

addr = s.addr
Net::HTTP.start(addr[3], addr[1]) do |http|
  http.request_get('/') do |res|
    dig = Digest::MD5.new
    res.read_body { |buf|
      dig.update(buf)
      # String#clear is important to reduce malloc overhead,
      # but most Ruby programmers don't do this :<
      buf.clear
    }
    puts dig.hexdigest
  end
end
----------

* lib/net/protocol (rbuf_consume): optimize for @rbuf.size == len
```


---Files--------------------------------
0001-net-protocol-optimize-large-read-case.patch (1.74 KB)


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