EventMachine Files¶ ↑
em-files solve problem of blocking disk IO when operating with large files. Use EventMachine for multiplexing reads and writes to small blocks performed in standalone EM
ticks. They speed down the file IO operations of sure, but allow running other tasks with them simultaneously (from EM
point of view).
There is, of sure, question whethet this all has sense as EM::defer
is availiable for handing these blocking tasks. But sometimes are situations, in which it’s undesirable to do them in separate thread.
API is similar to classic Ruby file IO represented by File class. See an example:
require "em-files" EM::run do EM::File::open("some_file.txt", "r") do |io| io.read(1024) do |data| # writing works by very similar # way, of sure puts data io.close() # it's necessary to do it in block too, because reading # is evented end end end
Support of Ruby API is limited to #open
, #close
, #read
and #write
methods only, so for special operations use simply:
EM::File::open("some_file.txt", "r") do |io| io.native # returns native Ruby File class object end
Special Uses¶ ↑
It’s possible to use also another IO objects than File
object by giving appropriate IO instance instead of filename to methods:
require "em-files" require "stringio" io = StringIO::new EM::run do EM::File::open(io) do |io| # some multiplexed operations end end
By this way you can also perform for example more time consuming operations by simple way (if they can be processed in block manner) using filters:
require "em-files" require "zlib" zip = Zlib::Deflate::new filter = Proc::new { |chunk| zip.deflate(chunk, Zlib::SYNC_FLUSH) } data = "..." # some data bigger than big EM::run do EM::File::write(data, filter) # done in several ticks end
#write
supports also copying data from another IO stream because it uses StringIO
internally. Simply give it IO object instead of String
. It will read it until EOF will occur.
Copyright¶ ↑
Copyright © 2011 – 2015 Martin Poljak. See LICENSE.txt
for further details.