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4a20d09523
in case of an absolute dupe just return the memoized post This works around issues with wordpress being crazy
60 lines
1.2 KiB
Ruby
60 lines
1.2 KiB
Ruby
class DistributedMemoizer
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# never wait for longer that 1 second for a cross process lock
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MAX_WAIT = 2
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LOCK = Mutex.new
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# memoize a key across processes and machines
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def self.memoize(key, duration = 60 * 60 * 24, redis = nil)
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redis ||= $redis
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redis_key = self.redis_key(key)
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unless result = redis.get(redis_key)
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redis_lock_key = self.redis_lock_key(key)
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start = Time.new
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got_lock = false
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while Time.new < start + MAX_WAIT && !got_lock
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LOCK.synchronize do
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got_lock = get_lock(redis,redis_lock_key)
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end
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sleep 0.001
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end
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unless result = redis.get(redis_key)
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result = yield
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redis.setex(redis_key, duration, result)
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end
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redis.del(redis_lock_key)
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end
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result
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end
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def self.redis_lock_key(key)
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"memoize_lock_" << key
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end
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def self.redis_key(key)
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"memoize_" << key
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end
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protected
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def self.get_lock(redis, redis_lock_key)
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redis.watch(redis_lock_key)
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current = redis.get(redis_lock_key)
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return false if current
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unique = SecureRandom.hex
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result = redis.multi do
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redis.setex(redis_lock_key, MAX_WAIT, unique)
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end
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redis.unwatch
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return result == ["OK"]
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end
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end
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