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class TimedCache
class Value < Struct.new(:value, :timestamp)
def self.json_create(hash)
new(*hash.values_at('value', 'timestamp'))
end
def as_json(*)
super | { JSON.create_id => self.class.name }
end
end
def initialize(name, ttl: 60, jitter: 1..5, &block)
@name = name
@ttl = ttl
@jitter = jitter
block or raise ArgumentError, 'block is required'
@block = block
@redis = Redis.new # RedisPool::Pool.connection(:timed_cache, configuration: :redis)
end
def namespaced(key)
"timed_cache:#{key}"
end
def value
now = Time.now
if stored = stored_value
if (now - @ttl).to_i >= stored.timestamp
Thread.new {
sleep @jitter
if stored_value.timestamp <= stored.timestamp
@redis.set namespaced(@name), new_value(now).to_json
end
}
end
stored.value
else
nv = new_value(now)
@redis.set namespaced(@name), nv.to_json
nv.value
end
end
def new_value(now)
Value.new(@block.(), now.to_i)
end
def stored_value
@redis.get(namespaced(@name)).full? { |s| ::JSON.parse(s, create_additions: true) rescue nil }
end
end
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