Class: EOAT::Cache::FileCache

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

Overview

Store cache to files on disk. Default use ~/.eoat/cache as destination directory.

Examples:

Set FileCache as a cache storage, with default destination directory

EOAT.cache = EOAT::Cache::FileCache.new

Set FileCache as a cache storage, with custom destination directory

EOAT.cache = EOAT::Cache::FileCache.new('path/to/cache/dir')

Author:

Instance Method Summary collapse

Constructor Details

#initialize(path = "#{ENV['HOME']}/.eoat/cache") ⇒ FileCache

Returns a new instance of FileCache.

Parameters:

  • path (String) (defaults to: "#{ENV['HOME']}/.eoat/cache") —

    destination path



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# File 'lib/eoat/cache/file_cache.rb', line 15

def initialize(path = "#{ENV['HOME']}/.eoat/cache")
  @path = path.chomp('/')
  FileUtils.mkpath(@path) unless File.exists?(@path)
  perform_cache_dir
end

Instance Method Details

#get(host, uri) ⇒ Object, NilClass

Get object from cache

Parameters:

  • host (String) —

    the request host string

  • uri (String) —

    the query string

Returns:

  • (Object, NilClass) —

    the instance of result class or nil if key not does not exist



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# File 'lib/eoat/cache/file_cache.rb', line 26

def get(host, uri)
  perform_cache_dir
  # Perform host string to md5 string
  host = EOAT::Cache.md5hash(host)
  # Perform uri string to md5 string
  uri = EOAT::Cache.md5hash(uri)
  # Combine parameters to path
  request_path = "#{@path}/#{host}/#{uri}"
  if File.exists?(request_path)
    # Set now in UTC timezone to timestamp
    now = Time.now.utc.to_i
    # Get all directories in request_path
    Dir["#{request_path}/*"].each do |dir|
      # Check timestamp
      if dir.split('/').last.to_i > now
        yaml = File.read("#{dir}/result.yml")
        yaml_hash = File.read("#{dir}/result.md5")
        if EOAT::Cache.md5hash(yaml) == yaml_hash
          return YAML::load(yaml)
        else
          FileUtils.rmtree("#{dir}")
        end
      else
        FileUtils.rmtree("#{dir}")
      end
    end
  end
  # Return false if data not found
  false
end

#save(host, uri, content) ⇒ Object

Save instance of result class.

Parameters:

  • host (String) —

    the request host string

  • uri (String) —

    the query string

  • content (Object) —

    the result class instance



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# File 'lib/eoat/cache/file_cache.rb', line 61

def save(host, uri, content)
  # Check expired
  perform_cache_dir
  # Calculate TTL in seconds
  expire = (content.cached_until - content.request_time).to_i
  # If TTL > EOAT.max_ttl set EOAT.max_tt as expire
  expire = expire > EOAT.max_ttl ? EOAT.max_ttl : expire
  # If 0 or a negative value, it does not save
  if expire > 0
    # Set expired as timestamp of date
    expired = (content.request_time + expire).to_i
    # Perform host string to md5 string
    host = EOAT::Cache.md5hash(host)
    # Perform uri string to md5 string
    uri = EOAT::Cache.md5hash(uri)
    # Combine parameters to path
    save_path = "#{@path}/#{host}/#{uri}/#{expired}"
    # This principle is not possible, but should be checked
    if File.exists?(save_path)
      raise EOAT::Exception::CacheSaveError.new("Save path: #{save_path} already exists!")
    end
    # Create directory
    FileUtils.mkpath(save_path)
    # Save instance to result.yml
    content_yaml = content.to_yaml
    File.write("#{save_path}/result.md5", EOAT::Cache.md5hash(content_yaml))
    File.write("#{save_path}/result.yml", content_yaml)
  end
end