debian-mirror-gitlab/lib/grafana/time_window.rb

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2020-04-08 14:13:33 +05:30
# frozen_string_literal: true
module Grafana
# Allows for easy formatting and manipulations of timestamps
# coming from a Grafana url
class TimeWindow
include ::Gitlab::Utils::StrongMemoize
def initialize(from, to)
@from = from
@to = to
end
def formatted
{
start: window[:from].formatted,
end: window[:to].formatted
}
end
def in_milliseconds
window.transform_values(&:to_ms)
end
private
def window
strong_memoize(:window) do
specified_window
rescue Timestamp::Error
default_window
end
end
def specified_window
RangeWithDefaults.new(
from: Timestamp.from_ms_since_epoch(@from),
to: Timestamp.from_ms_since_epoch(@to)
).to_hash
end
def default_window
RangeWithDefaults.new.to_hash
end
end
# For incomplete time ranges, adds default parameters to
# achieve a complete range. If both full range is provided,
# range will be returned.
class RangeWithDefaults
DEFAULT_RANGE = 8.hours
# @param from [Grafana::Timestamp, nil] Start of the expected range
# @param to [Grafana::Timestamp, nil] End of the expected range
def initialize(from: nil, to: nil)
@from = from
@to = to
apply_defaults!
end
def to_hash
{ from: @from, to: @to }.compact
end
private
def apply_defaults!
@to ||= @from ? relative_end : Timestamp.new(Time.now)
@from ||= relative_start
end
def relative_start
Timestamp.new(DEFAULT_RANGE.before(@to.time))
end
def relative_end
Timestamp.new(DEFAULT_RANGE.since(@from.time))
end
end
# Offers a consistent API for timestamps originating from
# Grafana or other sources, allowing for formatting of timestamps
# as consumed by Grafana-related utilities
class Timestamp
Error = Class.new(StandardError)
attr_accessor :time
# @param timestamp [Time]
def initialize(time)
@time = time
end
# Formats a timestamp from Grafana for compatibility with
# parsing in JS via `new Date(timestamp)`
def formatted
time.utc.strftime('%FT%TZ')
end
# Converts to milliseconds since epoch
def to_ms
time.to_i * 1000
end
class << self
# @param time [String] Representing milliseconds since epoch.
# This is what JS "decided" unix is.
def from_ms_since_epoch(time)
return if time.nil?
raise Error.new('Expected milliseconds since epoch') unless ms_since_epoch?(time)
new(cast_ms_to_time(time))
end
private
def cast_ms_to_time(time)
Time.at(time.to_i / 1000.0)
end
def ms_since_epoch?(time)
ms = time.to_i
ms.to_s == time && ms.bit_length < 64
end
end
end
end