71 lines
2.4 KiB
Ruby
71 lines
2.4 KiB
Ruby
# frozen_string_literal: true
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# A wrapper around `Rails.cache` that adds some extra helper methods. All
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# Danbooru code should use this class instead of using `Rails.cache` directly.
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#
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# In production, the cache is backed by Redis. In development, it's a temporary
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# in-memory cache.
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#
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# @see config/initializers/cache_store.rb
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# @see https://guides.rubyonrails.org/caching_with_rails.html#cache-stores
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# @see https://api.rubyonrails.org/classes/ActiveSupport/Cache/RedisCacheStore.html
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class Cache
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# Get multiple values from the cache at once.
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# @param keys [Array<String>] the list of keys to fetch
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# @param prefix [String] a prefix for each cache key
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# @return [Hash<String, Object>] a map from cache keys to cache values
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def self.get_multi(keys, prefix)
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sanitized_key_to_key_hash = keys.map do |key|
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["#{prefix}:#{Cache.hash(key)}", key]
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end.to_h
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sanitized_keys = sanitized_key_to_key_hash.keys
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sanitized_key_to_value_hash = Rails.cache.fetch_multi(*sanitized_keys) do |sanitized_key|
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key = sanitized_key_to_key_hash[sanitized_key]
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yield key
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end
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keys_to_values_hash = sanitized_key_to_value_hash.transform_keys(&sanitized_key_to_key_hash)
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keys_to_values_hash
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end
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# Get a value from the cache. If the value isn't in the cache, use the block
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# to generate the value.
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# @param key [String] the key to fetch
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# @param expiry_in_seconds [Integer] the lifetime of the cached value
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# @param options [Hash] options to pass to Rails.cache.fetch
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# @return the cached value
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def self.get(key, expiry_in_seconds = nil, **options, &block)
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Rails.cache.fetch(key, expires_in: expiry_in_seconds, **options, &block)
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end
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# Write a value to the cache.
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# @param key [String] the key to cache
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# @param value [Object] the value to cache
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# @param expiry_in_seconds [Integer] the lifetime of the cached value
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# @return the cached value
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def self.put(key, value, expiry_in_seconds = nil)
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Rails.cache.write(key, value, expires_in: expiry_in_seconds)
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value
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end
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# Remove a value from the cache.
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# @param key [String] the key to remove
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def self.delete(key)
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Rails.cache.delete(key)
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nil
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end
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# Clear the entire cache.
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def self.clear
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Rails.cache.clear
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end
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# Hash a cache key.
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# @param string [String] the cache key to hash
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# @return [String] the hashed key
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def self.hash(string)
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Digest::SHA256.base64digest(string)
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end
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end
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