Change cursors batch time formula on presence update #333
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@JoaoDiasAbly given this is a public repo, please can you add a description of the change directly, since not all people will be able to see the linked ticket. |
| @@ -105,7 +105,7 @@ export default class Cursors extends EventEmitter<CursorsEventMap> { | |||
| const channel = this.getChannel(); | |||
| const cursorsMembers = await channel.presence.get(); | |||
| this.cursorBatching.setShouldSend(cursorsMembers.length > 1); | |||
| this.cursorBatching.setBatchTime(cursorsMembers.length * this.options.outboundBatchInterval); | |||
| this.cursorBatching.setBatchTime(Math.ceil(cursorsMembers.length / 100) * this.options.outboundBatchInterval); | |||
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It's hard to understand why this is divided by 100 now?
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Before we were adjusting with cursorsMembers.length * this.options.outboundBatchInterval, which made the client-side latency climb linearly with the presence set. Since we have server-side batching now we don't need to make it so steep client-side. Therefore, the ticket suggestion was that it could climb with groups of 100s, which makes client-side batching latency grow much slower.
Example assuming outboundBatchInterval=25ms:
- if #presenceMembers <= 100: batchTime=25ms
- if #presenceMembers <= 200: batchTime=50ms
- if #presenceMembers <= 300: batchTime=75ms
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Ok thanks, makes sense, perhaps put that as a comment in the code?
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Added as a comment in the code
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https://ably.atlassian.net/browse/REA-1868
This PR changes the rate at which we adapt the (client-side) batch time, multiplying the
outboundBatchIntervalby slots of 100s instead of multiplying this value with the number of presence members.This change and smoothing of client-side batching interval is incentivised by the addition of server-side batching, which is now enabled by default for cursors channels.