Class: MixinBot::CacheStoreAdapter

Inherits:
Object
  • Object
show all
Defined in:
lib/mixin_bot/cache_store_adapter.rb

Overview

Adapter that lets any ActiveSupport::Cache-style store (Rails.cache with a Redis/Memcached/solid_cache backend, or a hand-rolled read/write/delete object) back the encrypted-message session cache.

API#post_encrypted_messages expects a store answering fetch(user_id) and store(user_id, sessions), where storing nil evicts. ActiveSupport caches speak read/write/delete instead, so this adapter translates:

session_store: MixinBot::CacheStoreAdapter.new(Rails.cache, expires_in: 12.hours)

The expires_in: option is passed through to cache.write as a TTL; the pipeline's one-shot expiry retry covers entries that lapse between fetch and send.

Constant Summary collapse

KEY_PREFIX = 
'mixin_bot/sessions'

Instance Method Summary collapse

Constructor Details

#initialize(cache = nil, expires_in: nil) ⇒ CacheStoreAdapter

Returns a new instance of CacheStoreAdapter.

Raises:



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# File 'lib/mixin_bot/cache_store_adapter.rb', line 22

def initialize(cache = nil, expires_in: nil)
  cache ||= Rails.cache if defined?(Rails)
  raise ArgumentError, 'a cache store is required' if cache.nil?

  @cache = cache
  @expires_in = expires_in
end

Instance Method Details

#fetch(user_id) ⇒ Object

Returns the cached session list for the recipient, or nil on a miss. A block passed by the caller is intentionally ignored: the block form of Rails' fetch means read-through caching, which is not wanted here.



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# File 'lib/mixin_bot/cache_store_adapter.rb', line 33

def fetch(user_id)
  @cache.read("#{KEY_PREFIX}/#{user_id}")
end

#store(user_id, sessions) ⇒ Object

Writes the session list for the recipient; nil evicts the entry.



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# File 'lib/mixin_bot/cache_store_adapter.rb', line 38

def store(user_id, sessions)
  key = "#{KEY_PREFIX}/#{user_id}"
  if sessions.nil?
    @cache.delete(key)
  elsif @expires_in
    @cache.write(key, sessions, expires_in: @expires_in)
  else
    @cache.write(key, sessions)
  end
end