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

_interval

Default time interval.

_interval: int = 300000

_cache

A dictionary containing the cached values.

final _cache = <String, Counter>{}

_updated

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

_updated: bool = false

_lastDumpTime

Time of the last dump.

_lastDumpTime: DateTime

_lastResetTime

Last time when was reset timer

_lastResetTime: DateTime

_resetTimeout

Timeout to reset timer

_resetTimeout: int = 0

Instance methods

beginTiming

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

CounterTiming beginTiming(String name)

• name: String - counter name of Interval type.
• returns: CounterTiming - callback object to end counter_timing.

clear

Clears (resets) a counter specified by its name.

void clear(String name)

• name: String - name of counter to clear.

clearAll

Clears (resets) all counters.

void clearAll()

configure

Configures component by passing configuration parameters.

@override

void configure(ConfigParams config)

• config: ConfigParams - configuration parameters to be set.

dump

Dumps (saves) the current values of counters.

void dump()

endTiming

Ends measurement of execution elapsed time and updates a specified counter.

@override

void endTiming(String? name, int elapsed)

• name: String? - counter’s name
• elapsed: int - 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.

Counter get(String? name, CounterType type)

• name: String - name of counter to retrieve.
• type: CounterType - counter type.
• returns: Counter - existing or newly created counter of the specified type.

getAll

Gets all captured counters.

List<Counter> getAll()

• returns: List<Counter> - list with counters.

getInterval

Gets the counters dump/save interval.

int getInterval()

• returns: int - interval in milliseconds.

increment

Increments a counter by given value.

@override

void increment(String name, int value)

• name: String - counter name of Increment type.
• value: int - value to add to the counter.

incrementOne

Increments counter by 1.

@override

void incrementOne(String name)

• name: String - counter name of Increment type.

last

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

@override

void last(String name, int value)

• name: String - counter name of Last type.
• value: int - last value to record.

save

Saves the current counters measurements.

void save(List<Counter> counters)

• counters: List<Counter> - current counters measurements to be saved.

setInterval

Sets the counters dump/save interval.

@override

void setInterval(int value)

• value: int - new interval in milliseconds.

stats

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

@override

void stats(String name, int value)

• name: String - counter name of Statistics type
• value: int - value to update statistics

timestamp

Records the given timestamp.

@override

void timestamp(String name, DateTime value)

• name: String - counter name of Timestamp type.
• value: DateTime - timestamp to record.

timestampNow

Records the current time as a timestamp.

@override

void timestampNow(String name)

• name: String - counter name of Timestamp type.

update

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

void _update()