`class Rate`

Tracks rate information over a sliding time window using a circular buffer.

Definitions

`def initialize(window: 60)`

Initialize the event rate counter.

Signature

parameter　window　Integer: The time window in seconds for rate calculations.

Implementation

def initialize(window: 60)
	@window = window
	@samples = [0] * @window
	@last_update = Array.new(@window, 0)
end

`attr :window`

The time window in seconds for rate calculations.

`def now`

Get the current time in seconds.

Signature

returns　Integer: The current monotonic time in seconds.

Implementation

def now
	::Process.clock_gettime(::Process::CLOCK_MONOTONIC).to_i
end

`def add(value = 1, time: self.now)`

Add a value to the current time slot.

Signature

parameter　value　Numeric: The value to add (default: 1)
parameter　time　Integer: The current time in seconds (default: monotonic time)

Implementation

def add(value = 1, time: self.now)
	index = time % @samples.size
	
	# If this slot hasn't been updated in a full window cycle, reset it
	if (time - @last_update[index]) >= @window
		@samples[index] = 0
	end
	
	@samples[index] += value
	@last_update[index] = time
end

`def total(time: self.now)`

Get the total count in the current window.

Signature

parameter　time　Integer: The current time in seconds (default: monotonic time)
returns　Numeric: The sum of all samples in the window.

Implementation

def total(time: self.now)
	@samples.each_with_index.sum do |value, index|
		# Only count samples that are within the window (inclusive of window boundary)
		if (time - @last_update[index]) <= @window
			value
		else
			0
		end
	end
end

`def per_second(time: self.now)`

Get the rate per second over the window.

Signature

parameter　time　Integer: The current time in seconds (default: monotonic time)
returns　Float: The average rate per second.

Implementation

def per_second(time: self.now)
	total(time: time).to_f / @window
end

`def per_minute(time: self.now)`

Get the rate per minute over the window.

Signature

parameter　time　Integer: The current time in seconds (default: monotonic time)
returns　Float: The average rate per minute.

Implementation

def per_minute(time: self.now)
	per_second(time: time) * 60
end