Class: InfoparkComponentCache::ConsistencyGuard Abstract

Inherits:

Object

• Object
• InfoparkComponentCache::ConsistencyGuard

Defined in:

lib/infopark_component_cache/consistency_guard.rb

Overview

This class is abstract.

This is abstract base class for any Cache Guards. Any class inheriting ConsistencyGuard should implement #consistent? and #guard!

Cache Guard is a class that promises some consistency, for example that no changes to the database accured between calls to #guard! and #consistent?

This consistency is crucial for the function of cache, because inconsistent cache is (automatically) invalidated.

Author:

• Tomasz Przedmojski tomasz.przedmojski@infopark.de

Direct Known Subclasses

Guards::AlwaysConsistent, Guards::LastChanged, Guards::NeverConsistent, Guards::ObjCount, Guards::ValidFrom, Guards::ValidUntil, Guards::ValuePresent

Instance Attribute Summary

• #component ⇒ Object readonly

  Returns the value of attribute component.

Instance Method Summary

• #cache ⇒ CacheStorage

  Instance of CacheStorage.

• #consistent? ⇒ Boolean abstract

  This method returns true if the consistenty guarded by this class is fulfilled and false otherwise.

• #guard! ⇒ Object abstract

  This method is called whenever cache is updated for the component.

• #initialize(component) ⇒ ConsistencyGuard constructor

  A new instance of ConsistencyGuard.

Constructor Details

#initialize(component) ⇒ ConsistencyGuard

Returns a new instance of ConsistencyGuard.

# File 'lib/infopark_component_cache/consistency_guard.rb', line 20

def initialize(component)
  @component = component
end

Instance Attribute Details

#component ⇒ Object (readonly)

Returns the value of attribute component.

# File 'lib/infopark_component_cache/consistency_guard.rb', line 18

def component
  @component
end

Instance Method Details

#cache ⇒ CacheStorage

Returns instance of CacheStorage.

Returns:

• (CacheStorage) —

  instance of CacheStorage

# File 'lib/infopark_component_cache/consistency_guard.rb', line 25

def cache
  CacheStorage.instance
end

#consistent? ⇒ Boolean

This method is abstract.

This method returns true if the consistenty guarded by this class is fulfilled and false otherwise.

Returns:

• (Boolean)

Raises:

• (TypeError)

# File 'lib/infopark_component_cache/consistency_guard.rb', line 32

def consistent?
  raise TypeError, "Abstract method consistent? called"
end

#guard! ⇒ Object

This method is abstract.

This method is called whenever cache is updated for the component. Any values checked by #consistent? can be persisted here. Use ##cache for persistence but mind the possible inconsistencies.

Raises:

• (TypeError)

# File 'lib/infopark_component_cache/consistency_guard.rb', line 40

def guard!
  raise TypeError, "Abstract method guard! called"
end