76 lines
2.3 KiB
Ruby
76 lines
2.3 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module Ci
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module Runner
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##
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# Runner Backoff class is an implementation of an exponential backoff
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# used when a runner communicates with GitLab. We typically use it when a
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# runner retries sending a build status after we created a build pending
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# state.
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#
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# Backoff is calculated based on the backoff slot which is always a power
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# of 2:
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#
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# 0s - 3s duration -> 1 second backoff
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# 4s - 7s duration -> 2 seconds backoff
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# 8s - 15s duration -> 4 seconds backoff
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# 16s - 31s duration -> 8 seconds backoff
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# 32s - 63s duration -> 16 seconds backoff
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# 64s - 127s duration -> 32 seconds backoff
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# 127s - 256s+ duration -> 64 seconds backoff
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#
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# It means that first 15 requests made by a runner will need to respect
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# following backoffs:
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#
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# 0s -> 1 second backoff (backoff started, slot 0, 2^0 backoff)
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# 1s -> 1 second backoff
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# 2s -> 1 second backoff
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# 3s -> 1 seconds backoff
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# (slot 1 - 2^1 backoff)
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# 4s -> 2 seconds backoff
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# 6s -> 2 seconds backoff
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# (slot 2 - 2^2 backoff)
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# 8s -> 4 seconds backoff
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# 12s -> 4 seconds backoff
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# (slot 3 - 2^3 backoff)
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# 16s -> 8 seconds backoff
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# 24s -> 8 seconds backoff
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# (slot 4 - 2^4 backoff)
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# 32s -> 16 seconds backoff
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# 48s -> 16 seconds backoff
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# (slot 5 - 2^5 backoff)
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# 64s -> 32 seconds backoff
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# 96s -> 32 seconds backoff
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# (slot 6 - 2^6 backoff)
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# 128s -> 64 seconds backoff
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#
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# There is a cap on the backoff - it will never exceed 64 seconds.
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#
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class Backoff
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def initialize(started)
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@started = started
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if duration < 0
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raise ArgumentError, 'backoff duration negative'
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end
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end
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def duration
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(Time.current - @started).ceil
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end
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def slot
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return 0 if duration < 2
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Math.log(duration, 2).floor - 1
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end
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def to_seconds
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2**[slot, 6].min
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end
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end
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end
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end
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end
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