Class: IdentityCache::MemoizedCacheProxy

Inherits:
Object
  • Object
show all
Defined in:
lib/identity_cache/memoized_cache_proxy.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cache_adaptor = nil) ⇒ MemoizedCacheProxy

Returns a new instance of MemoizedCacheProxy.



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 9

def initialize(cache_adaptor = nil)
  self.cache_backend = cache_adaptor || Rails.cache
  @key_value_maps = Hash.new { |h, k| h[k] = {} }
end

Instance Attribute Details

#cache_fetcher ⇒ Object (readonly)

Returns the value of attribute cache_fetcher.



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 7

def cache_fetcher
  @cache_fetcher
end

Instance Method Details

#cache_backend=(cache_adaptor) ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 14

def cache_backend=(cache_adaptor)
  if cache_adaptor.class.name == 'ActiveSupport::Cache::MemCacheStore'
    if cache_adaptor.respond_to?(:cas) || cache_adaptor.respond_to?(:cas_multi)
      unless cache_adaptor.is_a?(MemCacheStoreCAS)
        raise "#{cache_adaptor} respond to :cas or :cas_multi, that's unexpected"
      end
    else
      cache_adaptor.extend(MemCacheStoreCAS)
    end
  end

  if cache_adaptor.respond_to?(:cas) && cache_adaptor.respond_to?(:cas_multi)
    @cache_fetcher = CacheFetcher.new(cache_adaptor)
  else
    case cache_adaptor
    when ActiveSupport::Cache::MemoryStore, ActiveSupport::Cache::NullStore
      # no need for CAS support
    else
      warn("[IdentityCache] Missing CAS support in cache backend #{cache_adaptor.class} "\
           "which is needed for cache consistency")
    end
    @cache_fetcher = FallbackFetcher.new(cache_adaptor)
  end
end

#clear ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 134

def clear
  ActiveSupport::Notifications.instrument('cache_clear.identity_cache') do
    clear_memoization
    @cache_fetcher.clear
  end
end

#delete(key) ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 59

def delete(key)
  memoizing = memoizing?
  ActiveSupport::Notifications.instrument('cache_delete.identity_cache', memoizing: memoizing) do
    memoized_key_values.delete(key) if memoizing
    if (result = @cache_fetcher.delete(key))
      IdentityCache.logger.debug { "[IdentityCache] delete recorded for #{key}" }
    else
      IdentityCache.logger.error { "[IdentityCache] delete failed for #{key}" }
    end
    result
  end
end

#fetch(key) ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 72

def fetch(key)
  memo_misses = 0
  cache_misses = 0

  value = ActiveSupport::Notifications.instrument('cache_fetch.identity_cache') do |payload|
    payload[:resolve_miss_time] = 0.0

    value = fetch_memoized(key) do
      memo_misses = 1
      @cache_fetcher.fetch(key) do
        cache_misses = 1
        instrument_duration(payload, :resolve_miss_time) do
          yield
        end
      end
    end
    set_instrumentation_payload(payload, num_keys: 1, memo_misses: memo_misses, cache_misses: cache_misses)
    value
  end

  if cache_misses > 0
    IdentityCache.logger.debug { "[IdentityCache] cache miss for #{key}" }
  else
    IdentityCache.logger.debug do
      "[IdentityCache] #{memo_misses > 0 ? '(cache_backend)' : '(memoized)'} cache hit for #{key}"
    end
  end

  value
end

#fetch_multi(*keys) ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 103

def fetch_multi(*keys)
  memo_miss_keys = EMPTY_ARRAY
  cache_miss_keys = EMPTY_ARRAY

  result = ActiveSupport::Notifications.instrument('cache_fetch_multi.identity_cache') do |payload|
    payload[:resolve_miss_time] = 0.0

    result = fetch_multi_memoized(keys) do |non_memoized_keys|
      memo_miss_keys = non_memoized_keys
      @cache_fetcher.fetch_multi(non_memoized_keys) do |missing_keys|
        cache_miss_keys = missing_keys
        instrument_duration(payload, :resolve_miss_time) do
          yield missing_keys
        end
      end
    end

    set_instrumentation_payload(
      payload,
      num_keys: keys.length,
      memo_misses: memo_miss_keys.length,
      cache_misses: cache_miss_keys.length
    )
    result
  end

  log_multi_result(keys, memo_miss_keys, cache_miss_keys)

  result
end

#memoized_key_values ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 39

def memoized_key_values
  @key_value_maps[Thread.current]
end

#with_memoization ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 43

def with_memoization
  Thread.current[:memoizing_idc] = true
  yield
ensure
  clear_memoization
  Thread.current[:memoizing_idc] = false
end

#write(key, value) ⇒ Object 



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# File 'lib/identity_cache/memoized_cache_proxy.rb', line 51

def write(key, value)
  memoizing = memoizing?
  ActiveSupport::Notifications.instrument('cache_write.identity_cache', memoizing: memoizing) do
    memoized_key_values[key] = value if memoizing
    @cache_fetcher.write(key, value)
  end
end