Class: SiteDiff::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/sitediff/cache.rb

Overview

SiteDiff Cache Handler.

Constant Summary collapse

TIMESTAMP_FILE = 
'timestamp'

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Cache

Creates a Cache object.



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# File 'lib/sitediff/cache.rb', line 15

def initialize(opts = {})
  @create = opts[:create]

  # Read and Write tags are sets that can contain :before and :after.
  # They indicate whether we should use the cache for reading or writing.
  @read_tags = Set.new
  @write_tags = Set.new
  @timestamp_flag = { before: false, after: false }

  # The directory used by the cache for storage.
  @dir = opts[:directory] || '.'
end

Instance Attribute Details

#read_tags ⇒ Object

Returns the value of attribute read_tags.



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# File 'lib/sitediff/cache.rb', line 11

def read_tags
  @read_tags
end

#write_tags ⇒ Object

Returns the value of attribute write_tags.



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# File 'lib/sitediff/cache.rb', line 11

def write_tags
  @write_tags
end

Instance Method Details

#get(tag, path) ⇒ Object

Get data from cache.



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# File 'lib/sitediff/cache.rb', line 37

def get(tag, path)
  return nil unless @read_tags.include? tag

  filename = File.join(
    @dir,
    'snapshot',
    tag.to_s,
    *path.split(File::SEPARATOR)
  )

  filename = File.join(filename, 'index.html') if File.directory?(filename)
  return nil unless File.file? filename

  Marshal.load(File.read(filename))
end

#get_dir(directory) ⇒ Object

Ensures that a directory exists.



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# File 'lib/sitediff/cache.rb', line 105

def get_dir(directory)
  # Create the dir. Must go before cache initialization!
  @dir = Pathname.new(directory || '.')
  @dir.mkpath unless @dir.directory?
  @dir.to_s
end

#key(tag, path) ⇒ Object

TODO: Document this or remove it if unused.



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# File 'lib/sitediff/cache.rb', line 98

def key(tag, path)
  # Ensure encoding stays the same!
  Marshal.dump([tag, path.encode('UTF-8')])
end

#set(tag, path, result) ⇒ Object

Set data to cache.



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# File 'lib/sitediff/cache.rb', line 55

def set(tag, path, result)
  return unless @write_tags.include? tag

  save_timestamp(tag)
  filename = File.join(
    @dir,
    'snapshot',
    tag.to_s,
    *path.split(File::SEPARATOR)
  )

  filename = File.join(filename, 'index.html') if File.directory?(filename)
  filepath = Pathname.new(filename)
  unless filepath.dirname.directory?
    begin
      filepath.dirname.mkpath
    rescue Errno::EEXIST
      curdir = filepath
      curdir = curdir.parent until curdir.exist?
      tempname = "#{curdir.dirname}/#{curdir.basename}.temporary"
      # tempname = curdir.dirname + (curdir.basename.to_s + '.temporary')
      # May cause problems if action is not atomic!
      # Move existing file to dir/index.html first
      # Not robust! Should generate an UUID or something.
      if File.exist?(tempname)
        SiteDiff.log "Overwriting file #{tempname}", :warning
      end
      curdir.rename(tempname)
      filepath.dirname.mkpath
      # Should only happen in strange situations such as when the path
      # is foo/index.html/bar (i.e., index.html is a directory)
      if File.exist?("#{curdir}/index.html")
        SiteDiff.log "Overwriting file #{tempname}", :warning
      end
      File.rename(tempname, "#{curdir}/index.html")
      # tempname.rename(curdir + 'index.html')
    end
  end
  File.open(filename, 'w') { |file| file.write(Marshal.dump(result)) }
end

#tag?(tag) ⇒ Boolean

Is a tag cached? TODO: Rename it to is_cached? as it makes more sense.

Returns:

  • (Boolean) 


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# File 'lib/sitediff/cache.rb', line 31

def tag?(tag)
  File.directory?(File.join(@dir, 'snapshot', tag.to_s))
end