[collectd 6] cache: Provide the first metric value available alongside the first metric time. #4265
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…ded. This simplifies writing unit tests using the cache.
…nd value. Returning both in one call ensures these values are consistent, i.e. it avoids the case that there might have been an update inbewtween reading time and value.
This also improved the return values to give more information about which error condition occurred.
…d with a gauge metric.
eero-t
requested changes
Jan 31, 2024
eero-t
requested changes
Jan 31, 2024
eero-t
approved these changes
Jan 31, 2024
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The write_stackdriver plugin uses the first observed time to scale counters so they appear to start from zero. OpenTelemetry calls this inserting true reset points. The new API returns the first metric time and first metric time in one call for consistency and efficiency.
This PR contains a few other, smaller improvements to the cache:
uc_insert()anduc_get_rate()has been added.uc_init()function has been removed in favor of automatic initialization. This simplifies using the cache from unit tests.uc_get_rate()has been documented.ChangeLog: Daemon: The first observed metric value has been added to the metrics cache.