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https://issues.apache.org/jira/browse/IGNITE-18742?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Denis Chudov updated IGNITE-18742:
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Summary: Implement initial lease granting on placement driver side (was:
Implement initial lease granting for a maintenance phase of group lease
management)
> Implement initial lease granting on placement driver side
> ---------------------------------------------------------
>
> Key: IGNITE-18742
> URL: https://issues.apache.org/jira/browse/IGNITE-18742
> Project: Ignite
> Issue Type: Improvement
> Reporter: Alexander Lapin
> Priority: Major
> Labels: ignite-3
> Attachments: screenshot-1.png
>
>
> Maintenance phase of placement driver is the management of already existing
> leases by the placement driver's active actor.
> !screenshot-1.png!
> Describing in words, there should be a worker triggered once in a period of
> time equal to leaseInterval/2, that makes following:
> - it iterates over all partition groups managed by placement driver, and
> either extends their leases or chooses new, if there is no lease for group
> for some reason (it can be because leaseholder was never chosen, or actual
> leaseholder left the cluster, etc.);
> - if there is no lease, it should be assigned using lease candidates
> balancer, see IGNITE-18879 , otherwise the placement driver should define if
> the existing lease is goind to expire;
> - new timestamp (let's name it leaseValidUntil) until which the lease will
> be valid, should be calculated as currentTime + leaseInterval;
> - after that, placement driver should invoke meta storage to refresh data
> about leases, lease candidates and their new leaseValidUntil timestamps;
> - if invoke is successful (it can be not if there are two nodes considering
> themselves as the placement driver's active actors), LeaseGrantMessage
> containing leaseValidUntil should be sent to leases and lease candidates;
> - lease candidate is able to decline LeaseGrantMessage and sent
> LeaseGrantResponse with redirect proposal, containing alternative candidate.
> This proposal should also be handled with lease candidates balancer and as a
> result, following is possible: previously chosen candidate is enforced:
> placement driver sends LeaseGrantMessage(force=true) to the lease candidate,
> or the proposed candidate is accepted by placement driver;
> - if lease candidate accepts it's role, the placement driver makes invoke to
> meta storage, confirming new leaseholder and it's lease validness interval.
> Pseudocode:
> {code:java}
> scheduleAtFixedRate(leaseInterval / 2) {
> for (group in replicationGroups) {
> leaseValidUntil = now() + leaseInterval // getting timestamp until
> leases are prolonged
> lease = lease(group)
> if (lease == null) { // it can be null if these is no lease at all,
> or active lease left the cluster
> lease = leaseBalancer.get(group) // in this case lease is just a
> candidate
> }
> if (invokeMetaStorage(grantLease(lease, leaseValidUntil))) {
> sendLeaseGrantMessage(lease, leaseValidUntil) // send message to
> replica, response is handled by onLeaseGrantResponse
> }
> }
> }
> onLeaseGrantResponse(leaseGrantResponse) {
> leaseValidUntil = leaseGrantResponse.leaseValidUntil
> if (leaseGrantResponse.redirectProposal) {
> leaseCandidateNew =
> leaseBalancer.considerRedirectProposal(leaseGrantResponse.sender,
> leaseGrantResponse.redirectProposal);
> if (invokeMetaStorage(grantLease(leaseCandidateNew,
> leaseValidUntil))) {
> sendLeaseGrantMessage(leaseCandidateNew, leaseValidUntil, force)
> // force lease grant message
> }
> } else {
> assert(leaseGrantResponse.accepted)
> leaseholder = leaseGrantResponse.sender
> invokeMetaStorage(leaseConfirmed(leaseholder, leaseValidUntil))
> }
> }
> {code}
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