mruby-io-copy_stream

The implementation of IO.copy_stream method for mruby.

Feature

• Support pread(2)
• Support sendfile(2) if linux
• It doesn't have dependency to IO library.

Special spec of this library

• Use fd for system call if respond to fileno method.
• Use read and write method if doesn't have fd.
• Use seek method if doesn't have fd for src_offset option.

Performance

# bigfile is 440MB text file

t = Time.now
IO.copy_stream("bigfile", "bigfile-copy")
puts Time.now - t

t = Time.now
File.open("bigfile") do |src|
  IO.copy_stream(src, "bigfile-copy")
end
puts Time.now - t

t = Time.now
File.open("bigfile-copy", "w") do |dst|
  IO.copy_stream("bigfile", dst)
end
puts Time.now - t

t = Time.now
File.open("bigfile") do |src|
  File.open("bigfile-copy", "w") do |dst|
    IO.copy_stream(src, dst)
  end
end
puts Time.now - t

CRuby

$ ruby t.rb
0.407673
0.400015
0.395681
0.401305

mruby use this library with mruby-io

$ mruby t.rb
0.452422
0.419008
0.403466
0.412026

How to development with docker

$ docker-compose -f docker/docker-compose.yml build
$ docker-compose -f docker/docker-compose.yml run test

$ make test

See also

https://ruby-doc.org/core-2.4.1/IO.html#method-c-copy_stream