Class: Logster::RedisRateLimiter

Inherits:
Object
  • Object
show all
Defined in:
lib/logster/redis_store.rb

Constant Summary collapse

BUCKETS = 
6
PREFIX = 
"__LOGSTER__RATE_LIMIT".freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(redis, severities, limit, duration, redis_prefix = nil, callback = nil) ⇒ RedisRateLimiter

Returns a new instance of RedisRateLimiter.



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# File 'lib/logster/redis_store.rb', line 22

def initialize(redis, severities, limit, duration, redis_prefix = nil, callback = nil)
  @severities = severities
  @limit = limit
  @duration = duration
  @callback = callback
  @redis_prefix = redis_prefix
  @redis = redis
  @bucket_range = @duration / BUCKETS
  @mget_keys = (0..(BUCKETS - 1)).map { |i| "#{key}:#{i}" }
end

Instance Attribute Details

#callback ⇒ Object (readonly)

Returns the value of attribute callback.



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# File 'lib/logster/redis_store.rb', line 9

def callback
  @callback
end

#duration ⇒ Object (readonly)

Returns the value of attribute duration.



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# File 'lib/logster/redis_store.rb', line 9

def duration
  @duration
end

Class Method Details

.clear_all(redis, redis_prefix = nil) ⇒ Object 



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# File 'lib/logster/redis_store.rb', line 11

def self.clear_all(redis, redis_prefix=nil)
  prefix = key_prefix(redis_prefix)

  redis.eval "
  local keys = redis.call('keys', '*#{prefix}*')
  if (table.getn(keys) > 0) then
    redis.call('del', unpack(keys))
  end
  "
end

Instance Method Details

#callback_key ⇒ Object 



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# File 'lib/logster/redis_store.rb', line 78

def callback_key
  "#{key}:callback_triggered"
end

#check(severity) ⇒ Object 



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# File 'lib/logster/redis_store.rb', line 37

def check(severity)
  return unless @severities.include?(severity)
  time = Time.now.to_i
  num = bucket_number(time)
  redis_key = "#{key}:#{num}"

  current_rate = @redis.eval <<-LUA
    local bucket_number = #{num}
    local bucket_count = redis.call("INCR", "#{redis_key}")

    if bucket_count == 1 then
      redis.call("EXPIRE", "#{redis_key}", "#{bucket_expiry(time)}")
      redis.call("DEL", "#{callback_key}")
    end

    local function retrieve_rate ()
      local sum = 0
      local values = redis.call("MGET", #{mget_keys(num)})
      for index, value in ipairs(values) do
        if value ~= false then sum = sum + value end
      end
      return sum
    end

    return (retrieve_rate() + bucket_count)
  LUA

  if !@redis.get(callback_key) && (current_rate >= @limit)
    @callback.call(current_rate) if @callback
    @redis.set(callback_key, 1)
  end

  current_rate
end

#key ⇒ Object 



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# File 'lib/logster/redis_store.rb', line 72

def key
  # "_LOGSTER_RATE_LIMIT:012:20:30"
  # Triggers callback when log levels of :debug, :info and :warn occurs 20 times within 30 secs
  "#{key_prefix}:#{@severities.join("")}:#{@limit}:#{@duration}"
end

#retrieve_rate ⇒ Object 



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# File 'lib/logster/redis_store.rb', line 33

def retrieve_rate
  @redis.mget(@mget_keys).reduce(0) { |sum, value| sum + value.to_i }
end