47 lines
1.8 KiB
Ruby
47 lines
1.8 KiB
Ruby
module Gitlab
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module Metrics
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# Class for storing details of a single metric (label, value, etc).
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class Metric
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JITTER_RANGE = 0.000001..0.001
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attr_reader :series, :values, :tags
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# series - The name of the series (as a String) to store the metric in.
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# values - A Hash containing the values to store.
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# tags - A Hash containing extra tags to add to the metrics.
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def initialize(series, values, tags = {})
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@values = values
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@series = series
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@tags = tags
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end
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# Returns a Hash in a format that can be directly written to InfluxDB.
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def to_hash
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# InfluxDB overwrites an existing point if a new point has the same
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# series, tag set, and timestamp. In a highly concurrent environment
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# this means that using the number of seconds since the Unix epoch is
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# inevitably going to collide with another timestamp. For example, two
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# Rails requests processed by different processes may end up generating
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# metrics using the _exact_ same timestamp (in seconds).
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#
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# Due to the way InfluxDB is set up there's no solution to this problem,
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# all we can do is lower the amount of collisions. We do this by using
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# System.real_time which returns the nanoseconds as a Float providing
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# greater accuracy. We then add a small random value that is large
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# enough to distinguish most timestamps but small enough to not alter
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# the timestamp significantly.
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#
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# See https://gitlab.com/gitlab-com/operations/issues/175 for more
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# information.
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time = System.real_time(:nanosecond) + rand(JITTER_RANGE)
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{
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series: @series,
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tags: @tags,
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values: @values,
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timestamp: time.to_i
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}
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end
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end
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end
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end
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