Class: Pincerna::Cache

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

Overview

A utility class to handle caching.

Constant Summary collapse

EXPIRATIONS =

Expiration of keys.

{short: 1800, long: 2592000}
FILE =

Location of the cache file

Pincerna::Base::CACHE_ROOT + "/cache.db"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Creates a new cache object.



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# File 'lib/pincerna/cache.rb', line 27

def initialize
  FileUtils.mkdir_p(File.dirname(FILE))
  @data = Daybreak::DB.new(FILE)
  @flusher = EM.add_periodic_timer(5) { Pincerna::Cache.instance.flush }
end

Instance Attribute Details

#data ⇒ Daybreak::DB (readonly)

Returns The cache store.

Returns:

  • (Daybreak::DB) —

    The cache store.



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# File 'lib/pincerna/cache.rb', line 12

class Cache
  # Expiration of keys.
  EXPIRATIONS = {short: 1800, long: 2592000} # 30 min, 1 month

  # Location of the cache file
  FILE = Pincerna::Base::CACHE_ROOT + "/cache.db"

  attr_reader :data

  # Returns the instance of the cache.
  def self.instance
    @instance ||= Pincerna::Cache.new
  end

  # Creates a new cache object.
  def initialize
    FileUtils.mkdir_p(File.dirname(FILE))
    @data = Daybreak::DB.new(FILE)
    @flusher = EM.add_periodic_timer(5) { Pincerna::Cache.instance.flush }
  end

  # Closes the cache data.
  def destroy
    @flusher.cancel
    @data.close rescue nil
  end

  # Flush data into disk.
  def flush
    @data.flush
    @data.compact
  end

  # Use data from cache or fetches new data.
  #
  # @param key [String] The key of the data.
  # @param expiration [Fixnum] Expiration of new data, in seconds.
  def use(key, expiration)
    value = @data[key]

    if !value || Time.now.to_f > value[:expiration] then
      data = yield
      @data[key] = {data: data, expiration: Time.now.to_f + expiration}
      data
    else
      value[:data]
    end
  end
end

Class Method Details

.instance ⇒ Object

Returns the instance of the cache.



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# File 'lib/pincerna/cache.rb', line 22

def self.instance
  @instance ||= Pincerna::Cache.new
end

Instance Method Details

#destroy ⇒ Object

Closes the cache data.



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# File 'lib/pincerna/cache.rb', line 34

def destroy
  @flusher.cancel
  @data.close rescue nil
end

#flush ⇒ Object

Flush data into disk.



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# File 'lib/pincerna/cache.rb', line 40

def flush
  @data.flush
  @data.compact
end

#use(key, expiration) ⇒ Object

Use data from cache or fetches new data.

Parameters:

  • key (String) —

    The key of the data.

  • expiration (Fixnum) —

    Expiration of new data, in seconds.



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# File 'lib/pincerna/cache.rb', line 49

def use(key, expiration)
  value = @data[key]

  if !value || Time.now.to_f > value[:expiration] then
    data = yield
    @data[key] = {data: data, expiration: Time.now.to_f + expiration}
    data
  else
    value[:data]
  end
end