dynsampler
v0.0.2
Published
Dynamic sampling of events
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Dynamic Sampler
This is a collection of samplers that can be used to provide sample rates when sending data to services like honeycomb
Usage
With defaults:
import { PerKeyThroughput } from "dynamic-sampler";
const sampler = new PerKeyThroughput();
const rate = sampler.getSampleRate("my key");
With options
import { PerKeyThroughput } from "dynamic-sampler";
const sampler = new PerKeyThroughput({
clearFrequencySec: 100,
perKeyThroughputSec: 2
});
Choosing a Sampler
TODO
Implementing New Samplers
The Sampler
class includes:
- timer setup
- construction of initial state (
Map
s) getSampleRate
returns the rate for a given key
You can extend it to create new samplers. updateMaps
is the only
function that needs to be defined, but it is often useful to collect
additional configuration from the constructor:
import { Sampler } from "dynamic-sampler";
export class PerKey extends Sampler {
constructor(opts = {}) {
super(opts);
this.perKeyThroughputSec = opts.perKeyThroughputSec || 5;
}
updateMaps() {
if (this.currentCounts.size == 0) {
//no traffic in the last 30s. clear the result Map
this.savedSampleRates.clear();
return;
}
const actualPerKeyRate = this.perKeyThroughputSec * this.clearFrequencySec;
const newRates = new Map();
this.currentCounts.forEach((val, key) => {
newRates.set(key, Math.floor(Math.max(1, val / actualPerKeyRate)));
});
this.savedSampleRates = newRates;
}
}
Modifying getSampleRate
Sometimes it makes sense to check additional state in getSampleRate
and return a different result based on that. When overriding the
function call super.getSampleRate
.
class MySampler extends Sampler {
constructor(opts = {}) {
super(opts);
this.hasReceivedTraffic = false;
}
updateMaps() {
// other logic
this.hasReceivedTraffic = true;
}
getSampleRate(key) {
const superSampleRate = super.getSampleRate(key);
if (!this.hasReceivedTraffic) {
return this.goalSampleRate;
} else {
return superSampleRate;
}
}
}