node-stats-collector
Collector for runtime stats of a task
Usage
const StatsCollector = require('@vanioinformatika/stats-collector')
const maxErrorCount = 10 // if more than 10 errors occur, a maxErrorCountReached event will be emitted
const timeWindowMillis = 60 * 1000 // error occurences are counted in a 60 sec time window
const errorHistorySize = 100 // the last 100 errors are kept
const statCollector = new StatsCollector(maxErrorCount, timeWindowMillis, errorHistorySize)
statsCollector.on('maxErrorCountReached', () => {
console.log('Maximum error count reached, something should be done...')
})
...
try {
doSomeProcessing()
statsCollector.success() // processing was successful
} catch (err) {
statsCollector.error(err) // an error occured during processing
}
...
// publish runtime stats via HTTP
app.get('/stats', (req, res) => {
res.json(statsCollector.toJSON(true)) // return error history in the response too
})
API
Constructor
StatsCollector(maxErrorCount: integer, timeWindowMillis: integer, errorHistorySize: integer): StatsCounter
Parameters:
- maxErrorCount: The maximum number of errors before a
maxErrorCountReached
event is emitted - timeWindowMillis: The time window in milliseconds in which the number of errors are counted
- errorHistorySize: The size of the error history
success
success(): void
Registers processing success. Increases totalCounter
and totalSuccessCounter
.
success
error(error: Error | errors: Array<Error>): void
Registers processing failure. Increases totalCounter
and totalErrorCounter
.
Saves the error(s) in the errorHistory and recentErrors stores.
If the number of collected errors is greater than maxErrorCount
, a maxErrorCountReached
event is emitted.
The recentErrors
collector only stores the last maxErrorCount
number of errors.
See also resetRecentErrors()
.
resetRecentErrors
resetRecentErrors(): void
Resets the recentErrors
collector.
getRecentErrors
getRecentErrors(): Array<Error>
Returns the recently occured errors (the contents of the recentErrors
collector).
getErrorHistory
getErrorHistory(): Array<Error>
Returns all errors from the error history.
The error history stores the last errorHistorySize
number of errors since the StatsCollector instance is created.
getTotalCounter
getTotalCounter(): integer
Returns the number of success()
and error()
calls together since the StatsCollector instance is created.
getTotalSuccessCounter
getTotalSuccessCounter(): integer
Returns the number of successful processing (i.e. the number of success()
calls) since the StatsCollector instance is created.
getTotalErrorCounter
getTotalErrorCounter(): integer
Returns the number of errors since the StatsCollector instance is created.
Note that this may not equal to the number of error()
calls, since an error()
call may register multiple errors.
toJSON
toJSON (showErrorHistory: boolean): Object
Returns an object with the properties of the StatsCollector.
If showErrorHistory
is true the error history is returned as well. This can be useful e.g.
if you want to publish stats through an HTTP endpont.
toString
toString (showErrorHistory: boolean): Object
Returns some basic info about the StatsCollector object.