Implements: ICounters, IReconfigurable, ICounterTimingCallback

Description

The CachedCounters class allows you to create performace counters that measure and store those values in memory.

Important points

• Child classes can implement saving of the counters into various different destinations.

Configuration parameters

options:

• interval: interval in milliseconds to save current counters measurements (default: 5 mins)
• reset_timeout: timeout in milliseconds to reset the counters. 0 disables the reset (default: 0)

Constructors

Creates a new CachedCounters object.

CachedCounters()

Fields

_default_interval

Default time interval.

_default_interval = 300000

_cache

A dictionary containing the cached values.

_cache: dict

_updated

A boolean value that indicates whether the counter has been updated or not.

_updated: bool

_last_dump_time

Time of the last dump.

_last_dump_time: float

_interval

Time different between two updates.

_interval: float

Instance methods

begin_timing

Begins measurement of execution time interval. It returns CounterTiming object which has to be called at CounterTiming.end_timing to end the measurement and update the counter.

begin_timing(name: str): CounterTiming

• name: str - a counter name of Interval type.
• returns: CounterTiming - a callback object to end timing.

clear

Clears (resets) a counter specified by its name.

clear(name: str)

• name: str - a counter name to clear.

clear_all

Clears (resets) all counters.

clear_all()

configure

Configures component by passing configuration parameters.

configure(config: ConfigParams)

• config: ConfigParams - configuration parameters to be set.

dump

Dumps (saves) the current values of counters.

dump()

end_timing

Ends measurement of execution elapsed time and updates specified counter.

end_timing(name: str, elapsed: float)

• name: str - a counter name
• elapsed: float - execution elapsed time in milliseconds to update the counter.

get

Gets a counter specified by its name. It counter does not exist or its type doesn’t match the specified type it creates a new one.

get(name: str, typ: CounterType): Counter

• name: str - a counter name to retrieve.
• typ: CounterType - a counter type.
• returns: Counter - an existing or newly created counter of the specified type.

get_all

Gets all captured counters.

get_all(): List[Counter]

• returns: List[Counter] - a list with counters.

get_interval

Gets the counters dump/save interval.

get_interval(): float

• returns: float - the interval in milliseconds.

increment

Increments counter by given value.

increment(name: str, value: float)

• name: str - a counter name of Increment type.
• value: float - a value to add to the counter.

increment_one

Increments counter by 1.

increment_one(name: str)

• name: str - a counter name of Increment type.

last

Records the last calculated measurement value. Usually this method is used by metrics calculated externally.

last(name: str, value: float)

• name: str - a counter name of Last type.
• value: float - a last value to record.

_save

Saves the current counters measurements.

abstractmethod _save(counters: List[Counter])

• counters: List[Counter] - current counters measurements to be saved.

set_interval

Sets the counters dump/save interval.

set_interval(value: float)

• value: float - a new interval in milliseconds.

stats

Calculates min/average/max statistics based on the current and previous values.

stats(name: str, value: float)

• name: str - a counter name of Statistics type
• value: float - a value to update statistics

timestamp

Records the given timestamp.

timestamp(name: str, value: datetime.datetime)

• name: str - a counter name of Timestamp type.
• value: datetime.datetime - a timestamp to record.

timestamp_now

Records the current time as a timestamp.

timestamp_now(name: str)

• name: str - a counter name of Timestamp type.

_update

Makes counter measurements as updated and dumps them when timeout expires.

_update()