Class: OsCtl::Repo::Downloader::Cached

Inherits:
Base
  • Object
show all
Defined in:
lib/osctl/repo/downloader/cached.rb

Overview

Download image in a specified format and cache it locally

Constant Summary

Constants inherited from Base

Base::DEFAULT_ATTEMPTS, Base::DEFAULT_WAIT, Base::NETWORK_EXCEPTIONS

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#connect, #index_uri, #initialize, #request_get, #retryable_http_code?, #with_retries

Constructor Details

This class inherits a constructor from OsCtl::Repo::Downloader::Base

Instance Attribute Details

#repo ⇒ Object (readonly, protected)

Returns the value of attribute repo.



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# File 'lib/osctl/repo/downloader/cached.rb', line 92

def repo
  @repo
end

Instance Method Details

#cached_image_path(vendor, variant, arch, dist, vtag, format) ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 141

def cached_image_path(vendor, variant, arch, dist, vtag, format)
  path = nil

  with_cached_image(vendor, variant, arch, dist, vtag, format) do |t|
    unless t.cached?(format)
      raise CacheMiss, "Image #{t} not found in cache"
    end

    path = t.abs_cache_path(format)
  end

  path
end

#download(vendor, variant, arch, dist, vtag, format, open) ⇒ Array(String, [IO, nil]) (protected)

Returns ‘[image_path, io|nil]`.

Returns:

  • (Array(String, [IO, nil])) —

    ‘[image_path, io|nil]`



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# File 'lib/osctl/repo/downloader/cached.rb', line 95

def download(vendor, variant, arch, dist, vtag, format, open)
  path = fh = nil

  ensure_cache_dir

  with_retries do
    connect do |http|
      index = nil

      repo.lock_index do
        update_index(http)
        index = Remote::Index.from_file(repo, repo.index_path)
      end

      t = index.lookup(vendor, variant, arch, dist, vtag)

      raise ImageNotFound, t unless t
      raise FormatNotFound.new(t, format) unless t.has_image?(format)

      FileUtils.mkdir_p(t.abs_dir_path)

      t.lock(format) do
        path = fetch_image(http, t, format)
        fh = File.open(path, 'r') if open
      end
    end
  end

  [path, fh]
end

#ensure_cache_dir ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 260

def ensure_cache_dir
  FileUtils.mkpath(repo.path)
end

#fetch_image(http, t, format) ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 205

def fetch_image(http, t, format)
  uri = URI(t.abs_image_url(format))
  t_path = t.abs_cache_path(format)
  t_tmp_path = "#{t_path}.new"

  if t.cached?(format)
    headers = { 'If-Modified-Since' => File.stat(t_path).mtime.httpdate }

    request_get(http, uri, headers) do |res|
      case res.code
      when '200'
        File.open(t_tmp_path, 'w') do |f|
          res.read_body do |fragment|
            f.write(fragment)
          end
        end

        if res['last-modified']
          # Save the modtime for later requests
          FileUtils.touch(t_tmp_path, mtime: Time.httpdate(res['last-modified']))
        end

        File.rename(t_tmp_path, t_path)
        return t_path

      when '304'
        # image unchanged

      else
        raise BadHttpResponse, res.code
      end
    end

  else # download it
    request_get(http, uri) do |res|
      File.open(t_tmp_path, 'w') do |f|
        raise BadHttpResponse, res.code if res.code != '200'

        res.read_body do |fragment|
          f.write(fragment)
        end
      end

      if res['last-modified']
        # Save the modtime for later requests
        FileUtils.touch(t_tmp_path, mtime: Time.httpdate(res['last-modified']))
      end

      File.rename(t_tmp_path, t_path)
    end
  end

  t_path
end

#get(vendor, variant, arch, dist, vtag, format, opts = {}) {|downloaded| ... } ⇒ String

param opts [Hash]

Parameters:

  • opts (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (opts):

  • :force_check (Boolean)

Yield Parameters:

  • downloaded (String) —

    data

Returns:

  • (String) —

    path to image



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# File 'lib/osctl/repo/downloader/cached.rb', line 31

def get(vendor, variant, arch, dist, vtag, format, opts = {}, &block)
  force_check = if opts.has_key?(:force_check)
                  opts[:force_check]
                else
                  false
                end

  begin
    image_path, fh = download(
      vendor,
      variant,
      arch,
      dist,
      vtag,
      format,
      block ? true : false
    )
  rescue NetworkError, BadHttpResponse => e
    if force_check
      raise

    elsif block
      begin
        image_path, fh = read_from_cache(
          vendor,
          variant,
          arch,
          dist,
          vtag,
          format
        )
      rescue CacheMiss
        raise e
      end

    else
      begin
        image_path = cached_image_path(
          vendor,
          variant,
          arch,
          dist,
          vtag,
          format
        )
      rescue CacheMiss
        raise e
      end
    end
  end

  if block
    block.call(fh.read(32 * 1024)) until fh.eof?
    fh.close
  end

  File.absolute_path(image_path)
end

#list ⇒ Array<Remote::Image>

Returns:



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# File 'lib/osctl/repo/downloader/cached.rb', line 10

def list
  ensure_cache_dir

  with_retries do
    connect do |http|
      index = nil

      repo.lock_index do
        update_index(http)
        index = Remote::Index.from_file(repo, repo.index_path)
      end

      index.images
    end
  end
end

#read_from_cache(vendor, variant, arch, dist, vtag, format) ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 126

def read_from_cache(vendor, variant, arch, dist, vtag, format)
  path = fh = nil

  with_cached_image(vendor, variant, arch, dist, vtag, format) do |t|
    unless t.cached?(format)
      raise CacheMiss, "Image #{t} not found in cache"
    end

    path = t.abs_cache_path(format)
    fh = File.open(path, 'r')
  end

  [path, fh]
end

#update_index(http) ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 174

def update_index(http)
  uri = index_uri
  tmp_path = "#{repo.index_path}.new"

  if repo.has_index?
    headers = { 'If-Modified-Since' => File.stat(repo.index_path).mtime.httpdate }

    request_get(http, uri, headers) do |res|
      case res.code
      when '200'
        write_index(tmp_path, res)
        File.rename(tmp_path, repo.index_path)

      when '304'
        # index unchanged

      else
        raise BadHttpResponse, res.code
      end
    end

  else
    request_get(http, uri) do |res|
      raise BadHttpResponse, res.code if res.code != '200'

      write_index(tmp_path, res)
      File.rename(tmp_path, repo.index_path)
    end
  end
end

#with_cached_image(vendor, variant, arch, dist, vtag, format) ⇒ Object (protected)

Raises:



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# File 'lib/osctl/repo/downloader/cached.rb', line 155

def with_cached_image(vendor, variant, arch, dist, vtag, format)
  index = nil

  repo.lock_index do
    index = Remote::Index.from_file(repo, repo.index_path)
  rescue Errno::ENOENT
    raise CacheMiss, 'Repository index not found in cache'
  end

  t = index.lookup(vendor, variant, arch, dist, vtag)

  raise ImageNotFound, t unless t
  raise FormatNotFound.new(t, format) unless t.has_image?(format)

  t.lock(format) do
    yield(t)
  end
end

#write_index(path, res) ⇒ Object (protected) 



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# File 'lib/osctl/repo/downloader/cached.rb', line 264

def write_index(path, res)
  File.open(path, 'w') do |f|
    res.read_body do |fragment|
      f.write(fragment)
    end
  end

  return unless res['last-modified']

  # Save the modtime for later requests
  FileUtils.touch(
    path,
    mtime: Time.httpdate(res['last-modified'])
  )
rescue StandardError
  FileUtils.rm_f(path)
  raise
end