Implement incremental backoff and jitter #370
Description
Please see the example implementation in js here ably/ably-js#997
Incremental backoff and jitter was added to the features spec in ably/docs#1445
To implement this we need to change the retry behaviour for:
- When the client connection is in the
DISCONNECTEDstate - When a
RealtimeChannelis in theSUSPENDEDstate
The new retry behaviour is specified in RTB1 of the features spec.
RTB1a
The backoff coefficient described in RTB1a can be calculated in javascript like so:
function getBackoffCoefficient(n) {
return Math.min((n + 2) / 3, 2);
}RTB1b
The jitter coefficient described in RTB1b can be calculated in javascript like so:
function getJitterCoefficient() {
return 1 - Math.random() * 0.2;
}RTB1
The overall retry time calculation should look like:
function getRetryTime(initValue, n) {
return initValue * getBackoffCoefficient(n) * getJitterCoefficient();
}The following code can be used to test it:
[1, 2, 3, 4, 5].forEach((n) => {
console.log(getRetryTime(initValue, n));
});Which, with an initValue of 15 (seconds) should print something like:
13.917470451245713
18.415226855678757
20.444851032898747
26.650729887092275
27.803382948778786
┆Issue is synchronized with this Jira Story by Unito