Change service working_directory to not slurp file into memory

[billdueber]

Fixes #1128

Method #copy_stream_to_working_directory previously used ruby's
copy_stream, which reads the whole source stream into memory.

New #copy_stream_to_file uses IO#readpartial to ferry it around in
4k chunks.

IO#readpartial is preferred to #read because it doesn't assume the stream
is complete when first referenced. 4k is a common heap page size and
should be fairly efficient.

@samvera/hyrax-code-reviewers

[mjgiarlo]

@atz mind reviewing?

[jcoyne]

My understanding was that the problem was on this line

hyrax/app/services/hyrax/working_directory.rb

Line 35 in 4e8b1b0

copy_stream_to_working_directory(id, file.original_name, StringIO.new(file.content))

specifically: StringIO.new(file.content) I wonder if we could stop using Hydra::PCDM::File#content and instead create a Hydra::PCDM::File#content_as_stream

[jcoyne]

@billdueber Could we do something like:

fs.original_file.stream.each { |chunk| f.write(chunk) }

[atz]

@jcoyne: cannot assume original_file is what matters.

My first reaction is that I don't care, I plan on removing Hyrax::WorkingDirectory anyway as it becomes unnecessary with carrierwave. But secondly, why is the exception catching inside the loop? Don't you keep looping after the rescue?

[billdueber]

The exception should not be inside the loop. The code doesn't do what I set out to address. I feel like I'm in one of those "wanna get away" SouthWest commercials.

Sooo....closing.