collator-protocol-revamp: CollationManager and subsystem impl by alindima · Pull Request #8541 · paritytech/polkadot-sdk

alindima · 2025-05-15T10:33:24Z

Implements the CollationManager and the new collator protocol (validator side) subsystem.

Issues #8182 and #7752.

These are the big remaining parts which would enable us to test the entire implementation.

TODO:

add a couple more unit tests (see the suggestions at the bottom of the tests file)
polish the ClaimQueueState and verify if it's sufficiently covered by unit tests
- ClaimQueueState cosmetics #10334
- Fix ClaimQueue inconsistencies #10368
add metrics and polish logs - Add metrics to collator-protocol/validator-side-experimental #10730
add a CLI parameter for enabling the experimental subsystem (and remove the compile-time feature) -> Add --experimental-collator-protocol cli argument to enable the new collator protocol implementation #10285
implement registered paras update, using Add para_ids Runtime API #9055
do some manual zombienet tests with v1 protocol version and with restarting validators (including syncing with warp sync)
prdoc
Rollback
- 03e8915
- 05e1497
  These commits were added just to run the CI tests for this PR with the new experimental protocol

After merging:

versi testing

Uses a slightly modified version of the ClaimQueueState written by @tdimitrov in #7114.

…variant for the validator side

…rotocol-revamp-peer-manager

…p-peer-manager' into alindima/collator-protocol-revamp-reputation-db-draft

…of leaves

…p-reputation-db-draft' into alindima/collator-protocol-revamp-collation-manager

alindima

LGTM, i'm happy with this. Some more metrics and tests could be added but can be follow-ups.

Cannot approve since I'm the original author, but consider this my approval :D

alindima · 2026-01-23T10:15:55Z

polkadot/node/network/collator-protocol/src/validator_side/mod.rs

 mod tests;

-pub use metrics::Metrics;
+pub use crate::validator_side_metrics::Metrics;


it will probably be needed to add different metrics depending on the subsystem variant. It's good to have the common ones deduplicated but I'd also add some more for the new version

I'd like us to have finer grained metrics, including timers for all operations. But this can be a follow-up, to avoid keeping this monster around open forever

I preferred not to add metrics which we won't use so I just transferred what we already have.
I agree in tough situations extra metrics will be useful so it can be a followup - I didn't close #10402 for this reason.

alindima · 2026-01-23T10:17:30Z

polkadot/node/network/collator-protocol/src/validator_side_metrics.rs

 	handle_collation_request_result: prometheus::Histogram,
 	collator_peer_count: prometheus::Gauge<prometheus::U64>,
 	collation_request_duration: prometheus::Histogram,
+	// TODO: Not available for the new implementation. Remove with the old implementation.


conceptually, requesting unblocked collations are present in both variants

polkadot/node/network/collator-protocol/src/validator_side_experimental/common.rs

alindima · 2026-01-23T10:26:11Z

prdoc/pr_8541.prdoc

+doc:
+- audience: Node Operator
+  description: |-
+    This PR adds a new collator protocol (validator side) subsystem.


Probably deserves a bit more :D

...adot/node/network/collator-protocol/src/validator_side_experimental/collation_manager/mod.rs

polkadot/node/network/collator-protocol/src/validator_side/mod.rs

…erimental/collation_manager/mod.rs Co-authored-by: Alin Dima <[email protected]>

…n-manager

eskimor

The following improvements can be a followup, but the constants should really be fixed/properly argued why they make sense.

Follow up improvements (not for this PR, but so that they are noted somewhere):

Parallel fetch after some small timeout: Is implemented in legacy implementation, should be brought back & improved. This is a fix for us not having proper streaming and can help a great deal to mitigate impact on fetch attacks - @tdimitrov knows details.
Negative reputation bump on fetch problems: We might not be able to punish hard for single issues (as network issues can happen to honest nodes - measurements would be good), but if implemented properly (e.g. above parallel fetch) any real harm will only come from coordinated attacks, thus we should look into punishing harder on coordination.
Race condition fix
Timer should start at leaf activation - parallel fetches should likely alter that behavior even more (we can likely be more aggressive in fetching, if we have parallel fetches) - instead of waiting doing nothing, we might as well fetch what is there, if we can fetch more if it arrives.
Possibly others from my chat with @tdimitrov

Fix for this PR: Get constants in order - or have a proper argument why they are good as is.

eskimor · 2026-01-31T16:34:45Z

polkadot/node/network/collator-protocol/src/validator_side_experimental/common.rs

+/// saturated to this value.
+pub const MAX_SCORE: u16 = 35_000;
+/// Reputation bump for getting a valid candidate included in a finalized block.
+pub const VALID_INCLUDED_CANDIDATE_BUMP: u16 = 100;


This is not what we agreed on, ok I just found the reasoning above for the value - it only argues in one dimension (against the inactivity decay, which seems to be causing more problems than it solves), but not against the other axes/more important axis: Relationship to negative reputation changes and with regards to those, this value is completely off.

eskimor

On second thought, let's get this PR merged finally. Any further fixes can come in a followup.

alindima · 2026-02-02T09:43:25Z

Parallel fetch after some small timeout: Is implemented in legacy implementation, should be brought back & improved. This is a fix for us not having proper streaming and can help a great deal to mitigate impact on fetch attacks - @tdimitrov knows details.

Parallel fetch for the same claim queue spot? We do fetch in parallel if there are multiple claim queue slots available. This is esentially the same as in the old implementation

…n-manager

tdimitrov · 2026-02-02T11:35:32Z

Parallel fetch for the same claim queue spot?

Yes

paritytech-workflow-stopper · 2026-02-02T11:36:41Z

All GitHub workflows were cancelled due to failure one of the required jobs.
Failed workflow url: https://github.com/paritytech/polkadot-sdk/actions/runs/21588396729
Failed job name: fmt

tdimitrov · 2026-02-02T11:36:43Z

/cmd fmt

…n-manager

@eskimor

A followup from #8541 with changes requested by @eskimor: - Adjust the protocol parameters and add comments about the picked values - Simpler fetch mechanism - advertisements from unknown collators (those with 0 reputation) are delayed. Everything else is fetched immediately. --------- Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>

@eskimor

A followup from #8541 with changes requested by @eskimor: - Adjust the protocol parameters and add comments about the picked values - Simpler fetch mechanism - advertisements from unknown collators (those with 0 reputation) are delayed. Everything else is fetched immediately. --------- Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com> (cherry picked from commit 26bb41a)

alindima added 30 commits April 3, 2025 11:18

add enable-experimental-collator-protocol CLI flag and new subsystem …

4667163

…variant for the validator side

fix clap arg

96b2cd1

rollback experimental cli flag

1d283d5

WIP peer manager impl

73b61fd

continue impl

d943dbb

Merge remote-tracking branch 'origin/master' into alindima/collator-p…

2bfdaf0

…rotocol-revamp-peer-manager

make taplo happy

fa731c6

minor fix

1691ec8

Merge remote-tracking branch 'origin/master' into alindima/collator-p…

75f00f4

…rotocol-revamp-peer-manager

fix todo after merging previous PR

3b17c38

initial memory db impl

41127ae

satisfy clippy

2bf2b05

WIP

6fa2d4e

Merge remote-tracking branch 'origin/master' into alindima/collator-p…

f5ae202

…rotocol-revamp-peer-manager

review comments

32c30ea

switch to processing rep bumps only for finalized block notifications

5271ad7

add unit tests for Score primitive

86cd891

some unit tests

7ffde5c

some fixes and almost all needed unit tests for ConnectedPeers

b5e1b13

add test for update_reputation

81140bc

some fixes

c42c33b

add a log

608fcb0

Merge remote-tracking branch 'origin/master' into alindima/collator-p…

e37e6d3

…rotocol-revamp-peer-manager

enforce limit is non-zero

b23c4e1

Merge remote-tracking branch 'origin/alindima/collator-protocol-revam…

e71d4e8

…p-peer-manager' into alindima/collator-protocol-revamp-reputation-db-draft

fix merge damage, most importantly handling finalized blocks instead …

24a9097

…of leaves

Merge remote-tracking branch 'origin/alindima/collator-protocol-revam…

4205200

…p-reputation-db-draft' into alindima/collator-protocol-revamp-collation-manager

WIP

82078e6

still WIP

7a490a9

more work

c82006a

tdimitrov added 2 commits January 23, 2026 11:48

Adjust MAX_SCORE, FAILED_FETCH_SLASH and INVALID_COLLATION_SLASH

e1c301d

clippy

c5d5210

tdimitrov requested a review from eskimor January 23, 2026 11:10

tdimitrov mentioned this pull request Jan 23, 2026

A collator providing advertisement late might avoid reputation decrease in collator protocol revamp #10887

Open

alindima commented Jan 23, 2026

View reviewed changes

tdimitrov and others added 8 commits January 23, 2026 15:33

Update polkadot/node/network/collator-protocol/src/validator_side_exp…

89cd009

…erimental/collation_manager/mod.rs Co-authored-by: Alin Dima <[email protected]>

spelling

8165457

prdoc

d088c5d

Move non-pub types in collation_manager after the pub types

4ac381f

fix a log line

c9a658c

Increase INVALID_COLLATION_SLASH

bc237d5

Merge branch 'master' into alindima/collator-protocol-revamp-collatio…

9f36299

…n-manager

Merge branch 'master' into alindima/collator-protocol-revamp-collatio…

6574a59

…n-manager

eskimor requested changes Jan 31, 2026

View reviewed changes

eskimor approved these changes Jan 31, 2026

View reviewed changes

Merge branch 'master' into alindima/collator-protocol-revamp-collatio…

c26bfc5

…n-manager

Update from github-actions[bot] running command 'fmt'

53d7389

tdimitrov enabled auto-merge February 2, 2026 13:52

Merge branch 'master' into alindima/collator-protocol-revamp-collatio…

fd06d5e

…n-manager

tdimitrov added this pull request to the merge queue Feb 4, 2026

Merged via the queue into master with commit a40ab3c Feb 4, 2026
308 of 311 checks passed

tdimitrov deleted the alindima/collator-protocol-revamp-collation-manager branch February 4, 2026 10:03

tdimitrov mentioned this pull request Feb 6, 2026

Collator protocol revamp - update calculate_delay #11008

Merged

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alindima commented May 15, 2025 •

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