Incremental decommit spec

[ch1bo]

Only specification changes for #1057 to get them merged first as described in #1473.

💅 Marked sections red that are about to change with incremental decommits.

💅 Adds decrementTx which removes UTxO from the head state to protocol overview, on-chain and off-chain sections.

💅 Updates close, contest and fanout steps accordingly.

💅 Uses a "version counting" scheme to distinguish cases where the same snapshot is used to decrement and close the head.

💅 Removes $\mathcal{T}_{\mathsf{all}}$ book-keeping and makes snapshots request full transactions. Adds a note that requesting only transaction ids is possible if all parties keep an index. This simplifies the specification (but departs from a 1:1 mapping to implemented protocol logic in Hydra.HeadLogic)

💅 (Re-)introduces snapshot objects to group confirmed variables (e.g. $\bar{s}, \bar{v}$) which are just kept to refer to them later on in close.

---

• CHANGELOG updated or not needed
• Documentation updated
• Haddocks not needed
• No new TODOs introduced or explained herafter
  • Figures are not updated
  • Some handwavy-ness when dealing with $tx_\omega$ and interface between off-chain and on-chain in regards with $\mathsf{CloseType}$ is unsharp

[github-actions]

Transactions Costs

Sizes and execution budgets for Hydra protocol transactions. Note that unlisted parameters are currently using arbitrary values and results are not fully deterministic and comparable to previous runs.

Metadata
Generated at	2024-07-01 14:31:13.328650046 UTC
Max. memory units	14000000
Max. CPU units	10000000000
Max. tx size (kB)	16384

Script summary

Name	Hash	Size (Bytes)
νInitial	baafeb5dc37bbe6e068784746bda0a3b1bb1d034fa0c55270f6079c1	4082
νCommit	fe7af84822bcba542fae377ae7311fc5fd20152f925ccd980f73ecdc	2061
νHead	93c08c55e804d7f82ca545a01883b5fda6a6d3623cb78885625800ae	9366
μHead	5e65c73722b4bb3f0cbfcc8433e1dcdfea099eaf0a43060f1731a65b*	4237

• The minting policy hash is only usable for comparison. As the script is parameterized, the actual script is unique per Head.

Cost of Init Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	4818	5.89	2.31	0.43
2	5019	7.29	2.86	0.45
3	5221	8.69	3.42	0.47
5	5623	11.67	4.60	0.53
10	6628	18.59	7.32	0.64
58	16278	86.13	33.97	1.81

Cost of Commit Transaction

This is using ada-only outputs for better comparability.

UTxO	Tx size	% max Mem	% max CPU	Min fee ₳
1	559	9.69	3.82	0.28
2	746	12.48	5.10	0.32
3	933	15.33	6.40	0.36
5	1312	21.26	9.09	0.45
10	2249	37.35	16.27	0.67
25	5057	96.42	41.75	1.45

Cost of CollectCom Transaction

Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
1	56	543	14.78	5.90	0.34
2	114	658	23.14	9.35	0.43
3	170	768	33.02	13.48	0.55
4	226	874	44.51	18.30	0.68
5	284	984	57.19	23.69	0.83
6	339	1095	72.14	30.01	1.00
7	394	1205	91.51	38.07	1.22

Cost of Close Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	597	8.31	4.61	0.28
2	773	9.46	6.01	0.30
3	920	10.12	7.06	0.32
5	1244	11.97	9.55	0.37
10	2029	16.75	15.85	0.49
50	8367	50.95	64.12	1.39

Cost of Contest Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	630	8.60	4.71	0.28
2	716	8.92	5.45	0.29
3	906	10.05	6.87	0.32
5	1262	12.36	9.69	0.38
10	2060	16.72	15.71	0.49
50	8022	51.83	63.57	1.38

Cost of Abort Transaction

Some variation because of random mixture of still initial and already committed outputs.

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	4693	16.95	7.34	0.55
2	4802	27.72	12.09	0.67
3	4887	37.46	16.24	0.79
4	5143	55.23	24.23	1.00
5	5317	78.76	34.78	1.27
6	5378	98.23	43.27	1.49

Cost of FanOut Transaction

Involves spending head output and burning head tokens. Uses ada-only UTxO for better comparability.

Parties	UTxO	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
5	0	0	4652	7.82	3.27	0.44
5	1	57	4686	9.18	4.07	0.46
5	5	284	4820	13.58	6.83	0.52
5	10	568	4990	19.55	10.48	0.60
5	20	1140	5331	31.29	17.70	0.77
5	30	1708	5671	42.61	24.75	0.92
5	40	2274	6008	53.93	31.80	1.08
5	50	2846	6349	65.47	38.94	1.24
5	79	4495	7331	98.97	59.67	1.70

End-To-End Benchmark Results

This page is intended to collect the latest end-to-end benchmarks results produced by Hydra's Continuous Integration system from the latest master code.

Please take those results with a grain of salt as they are currently produced from very limited cloud VMs and not controlled hardware. Instead of focusing on the absolute results, the emphasis should be on relative results, eg. how the timings for a scenario evolve as the code changes.

Generated at 2024-07-01 14:33:32.135828906 UTC

Baseline Scenario

Number of nodes	1
Number of txs	3000
Avg. Confirmation Time (ms)	4.394972370
P99	8.998408079999956ms
P95	5.835352799999999ms
P50	4.101889ms
Number of Invalid txs	0

Three local nodes

Number of nodes	3
Number of txs	9000
Avg. Confirmation Time (ms)	22.273366882
P99	114.13340576000006ms
P95	30.701589799999997ms
P50	19.757759999999998ms
Number of Invalid txs	0

[github-actions]

Test Results

437 tests  ±0   425 ✅ ±0   15m 20s ⏱️ -44s
143 suites ±0    12 💤 ±0 
  5 files   ±0     0 ❌ ±0 

Results for commit 30a1a50. ± Comparison against base commit ff72844.

♻️ This comment has been updated with latest results.