Class: Cache

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

Direct Known Subclasses

FileCache

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Creates a basic Cache with the UTC timezone



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# File 'lib/libcache/cache.rb', line 9

def initialize
  ENV['TZ'] = 'UTC'
  @scheduler = Rufus::Scheduler.new
  @time_tracker = Hash.new
end

Instance Attribute Details

#expiry_time ⇒ Object

Returns the value of attribute expiry_time.



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# File 'lib/libcache/cache.rb', line 6

def expiry_time
  @expiry_time
end

#max_size ⇒ Object

Returns the value of attribute max_size.



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# File 'lib/libcache/cache.rb', line 6

def max_size
  @max_size
end

#refresh ⇒ Object

Returns the value of attribute refresh.



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# File 'lib/libcache/cache.rb', line 6

def refresh
  @refresh
end

#store ⇒ Object

Returns the value of attribute store.



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# File 'lib/libcache/cache.rb', line 6

def store
  @store
end

Instance Method Details

#check_refresh(key) ⇒ Object

Refreshes an object if it has been invalidated

Parameters:

  • key (String) —

    The key value used to identify an object in the cache

Returns:

  • (Object) —

    The refreshed object that is recalled from the refresh method



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# File 'lib/libcache/cache.rb', line 59

def check_refresh(key)
  if @cache[key] == nil && !has_refresh?
    val = refresh.call(key)
    put(key, val)
    return val
  end
end

#create_store ⇒ Object

Initializes the cache store



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# File 'lib/libcache/cache.rb', line 16

def create_store
  @cache = Hash.new
end

#exists?(key) ⇒ Boolean

Checks if a key-value pair exists in the cache

Parameters:

  • key (String) —

    The key value used to identify an object in the cache

Returns:

  • (Boolean) —

    The existence of the key in the cache



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# File 'lib/libcache/cache.rb', line 52

def exists?(key)
  return @cache.key?(key)
end

#get(key) ⇒ Object

Gets the object that corresponds with the key

Parameters:

  • key (String) —

    The key value used to identify an object in the cache

Returns:

  • (Object) —

    The object that corresponds with the key



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# File 'lib/libcache/cache.rb', line 44

def get(key)
  check_refresh(key)
  return @cache[key]
end

#get_size ⇒ Object 



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# File 'lib/libcache/cache.rb', line 72

def get_size
  return @cache.size
end

#has_refresh? ⇒ Boolean

Returns Checks if the cache has a refresh method.

Returns:

  • (Boolean) —

    Checks if the cache has a refresh method



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# File 'lib/libcache/cache.rb', line 68

def has_refresh?
  return refresh == nil
end

#invalidate(key) ⇒ Object

Deletes a key-value pair from the cache

Parameters:

  • key (String) —

    The key value used to identify an object in the cache



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# File 'lib/libcache/cache.rb', line 78

def invalidate(key)
  @cache.delete key
end

#invalidateAll ⇒ Object

Clears all items in the cache



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# File 'lib/libcache/cache.rb', line 83

def invalidateAll
  @cache.clear
end

#put(key, value) ⇒ Object

Places an object inside the cache and handles max size eviction

Parameters:

  • key (String) —

    The key value used to identify an object in the cache

  • value (Object) —

    The object to be placed in the cache



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# File 'lib/libcache/cache.rb', line 23

def put(key, value)
  # removed oldest entry if max_size is approached
  if max_size != nil
    if @cache.size >= max_size - 1
      key, value = @time_tracker.values.sort {|v| Time.now - v }.reverse.first
      invalidate(key)
      @time_tracker.delete(key)
    end
    @time_tracker[key] = Time.now
  end
  @cache[key] = value
  if expiry_time != nil
    @scheduler.in expiry_time, :blocking => true do
      invalidate key
    end
  end
end