Class: Flipper::Adapter

Inherits:
Object
  • Object
show all
Defined in:
lib/flipper/adapter.rb

Overview

Internal: Adapter wrapper that wraps vanilla adapter instances with local caching.

So what is this local cache crap?

The main goal of the local cache is to prevent multiple queries to an adapter for the same key for a given amount of time (per request, per background job, etc.).

To facilitate with this, there is an included local cache middleware that enables local caching for the length of a web request. The local cache is enabled and cleared before each request and cleared and reset to original value after each request.

Examples

To see an example adapter that this would wrap, checkout the [memory adapter included with flipper](github.com/jnunemaker/flipper/blob/master/lib/flipper/adapters/memory.rb).

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(adapter, local_cache = {}) ⇒ Adapter

Internal: Initializes a new instance

adapter - Vanilla adapter instance to wrap. Just needs to respond to

read, write, delete, set_members, set_add, and set_delete.

local_cache - Where to store the local cache data (default: {}).

Must respond to fetch(key, block), delete(key) and clear.



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# File 'lib/flipper/adapter.rb', line 53

def initialize(adapter, local_cache = {})
  @adapter = adapter
  @local_cache = local_cache
end

Instance Attribute Details

#adapter ⇒ Object (readonly)

Returns the value of attribute adapter.



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# File 'lib/flipper/adapter.rb', line 44

def adapter
  @adapter
end

#local_cache ⇒ Object (readonly)

Returns the value of attribute local_cache.



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# File 'lib/flipper/adapter.rb', line 44

def local_cache
  @local_cache
end

Class Method Details

.wrap(object) ⇒ Object

Internal: Wraps vanilla adapter instance for use internally in flipper.

object - Either an instance of Flipper::Adapter or a vanilla adapter instance

Examples

adapter = Flipper::Adapters::Memory.new
instance = Flipper::Adapter.new(adapter)

Flipper::Adapter.wrap(instance)
# => Flipper::Adapter instance

Flipper::Adapter.wrap(adapter)
# => Flipper::Adapter instance

Returns Flipper::Adapter instance



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# File 'lib/flipper/adapter.rb', line 36

def self.wrap(object)
  if object.is_a?(Flipper::Adapter)
    object
  else
    new(object)
  end
end

Instance Method Details

#delete(key) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 79

def delete(key)
  @adapter.delete(key).tap { expire_local_cache(key) }
end

#eql?(other) ⇒ Boolean Also known as: ==

Returns:

  • (Boolean) 


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# File 'lib/flipper/adapter.rb', line 99

def eql?(other)
  self.class.eql?(other.class) && adapter == other.adapter
end

#read(key) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 67

def read(key)
  if using_local_cache?
    cache(key) { @adapter.read(key) }
  else
    @adapter.read(key)
  end
end

#set_add(key, value) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 91

def set_add(key, value)
  @adapter.set_add(key, value).tap { expire_local_cache(key) }
end

#set_delete(key, value) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 95

def set_delete(key, value)
  @adapter.set_delete(key, value).tap { expire_local_cache(key) }
end

#set_members(key) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 83

def set_members(key)
  if using_local_cache?
    cache(key) { @adapter.set_members(key) }
  else
    @adapter.set_members(key)
  end
end

#use_local_cache=(value) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 58

def use_local_cache=(value)
  local_cache.clear
  @use_local_cache = value
end

#using_local_cache? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/flipper/adapter.rb', line 63

def using_local_cache?
  @use_local_cache == true
end

#write(key, value) ⇒ Object 



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# File 'lib/flipper/adapter.rb', line 75

def write(key, value)
  @adapter.write(key, value).tap { expire_local_cache(key) }
end