ASAB Metrics Interpretation¤

Metrics Service not only creates new metrics but also periodically collects their values and sends them to selected databases. Every 60 seconds in the application lifetime, Metrics Service gathers values of all ASAB metrics. All Counters (and metric types that inherit from Counter) reset at this event to their initial values by default. Interpretation of ASAB Counters is affected by their resetable nature. Even though they monotonously increase, resetting every minute gives them a different meaning. In a long-term observation (that's how you most probably monitor the metrics in time-series databases), these metrics count events per minute. Thus, resettable Counters are presented to the Prometheus database as gauge-type metrics. Set the reset argument to False when creating a new Counter to disable Counter resetting. This periodic "flush" cycle also causes 60s delay of metric propagation into supported time-series databases. See the Timestamp section explaining the origin of a timestamp in each metric record.

Initial Values¤

You can initiate your metric instance with or without initial values. Initial values are always present and presented to databases even without a single event changing the metric values. You will always find a pair of value name and its value in resulting dataset. Values (name and value pairs) added during runtime last only 60s. You might spot this feature as missing values in the resulting time-series dataset.

Timestamp¤

Timestamp contains the record of the precise moment the metric's value was created or committed to the database. There are two types of metrics: resettable (is_reset = True) and non-resettable (is_reset = False). To reset a metric means to set it back to its initial value (for example, back to 0). The metric's type is determined by the reset: bool = True parameter of the metric's constructor at the moment of creation. We measure values of non-resettable metrics at the time of their creation (there are several possible methods based on the metric's general logic), while the resettable ones are measured when we reset the data (which is also the moment of them being sent into the database).

Metric Type	Description / Methods	Origin of the timestamp	is_reset
`Gauge`	Stores single numerical values which can go up and down. `set()`	When value is set. `set()`	False
`Counter` (Allows dynamic tags)	A cumulative metric; values can increase or decrease. Never stops. `add()`, `sub()`	When value is set. `add()` or `sub()`	False
`Counter` (Allows dynamic tags)	A cumulative metric; values can increase or decrease. Set to 0 every 60 seconds.	On `flush()`, every 60 seconds	True
`EPSCounter`	Divides the count of events by the time of the application run.	On `flush()`, every 60 seconds	False
`EPSCounter`	Divides the count of events by the time difference between measurements.	On `flush()`, every 60 seconds	True
`DutyCycle`	The fraction of one period in which a signal/system is active. A 60% DC means the signal is on 60% and off 40% of the time.	On `flush()`, every 60 seconds	True
`Aggregation Counter` (Allows dynamic tags)	Keeps track of max or min value of the Counter. Keeps maximum value by default.	When value is set. `set()`	False
`Aggregation Counter` (Allows dynamic tags)	Keeps track of max or min value of the Counter in each 60s window. Keeps maximum value by default.	On `flush()`, every 60 seconds	True
`Histogram` (Allows dynamic tags)	Cumulative histogram with a `set()` method.	When value is set. `set()`	False
`Histogram` (Allows dynamic tags)	Cumulative histogram with a `set()` method.	On `flush()`, every 60 seconds	True