Support the withdraw zero trick

[ch1bo]

Closes #1795

We can mock the ledger's certificate state with reward accounts for all withdrawals with 0 value in a transaction. This will allow included scripts with Rewarding script purpose to run once for the transaction.

The idea of mocking the certificate state emerged in a discussion with @colll78.

We can remove this once CIP-112 is implemented in the cardano-ledger.

---

• CHANGELOG updated
• Documentation updated -> new How-to
• Haddocks updated
• No new TODOs introduced

[github-actions]

Transaction cost differences

Script summary

Name	Size (Bytes)
νInitial	-
νCommit	-
νHead	-
μHead	-
νDeposit	-

Init transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	-	-	-
5	-	-	-	-
10	-	-	-	-
40	-	-	-	-

Commit transaction costs

UTxO	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	-	-	-
5	-	-	-	-
10	-	-	-	-
54	-	-	-	-

CollectCom transaction costs

Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-	-
2	-	-	-	-	-
3	-	-	-	-	-
4	-	-	-	-	-
5	-	-	-	-	-
6	-	-	-	-	-
7	-	-	-	-	-
8	-	-	-	-	-

Cost of Increment Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	+0.39	+0.09	-
5	-	-	-	-
10	-	-	-	-
37	-	-	-	-

Cost of Decrement Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	-	-	-
5	-	-	-	-
10	-	-	-	-
40	-	-	-	-

Close transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	-	-	-
5	-	-	-	-
10	-	-	-	-
34	-	-	-	-

Contest transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	-	-	-	-
2	-	-	-	-
3	-	-	-	-
5	-	-	-	-
10	-	-	-	-
27	-	-	-	-

FanOut transaction costs

UTxO, Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
(0, 10)	-	-	-	-	-
(1, 10)	-	-	-	-	-
(5, 10)	-	-	-	-	-
(10, 10)	-	-	-	-	-
(20, 10)	-	-	-	-	-
(37, 10)	-	-	-	-	-

[github-actions]

Transaction 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	2025-04-02 12:25:44.450971537 UTC
Max. memory units	14000000
Max. CPU units	10000000000
Max. tx size (kB)	16384

Script summary

Name	Hash	Size (Bytes)
νInitial	c8a101a5c8ac4816b0dceb59ce31fc2258e387de828f02961d2f2045	2652
νCommit	61458bc2f297fff3cc5df6ac7ab57cefd87763b0b7bd722146a1035c	685
νHead	0e35115a2c7c13c68ecd8d74e4987c04d4539e337643be20bb3274bd	14756
μHead	57166715eadb8d3135964325c016eea546c21e1c0aae974ca67df9a5*	5541
νDeposit	ae01dade3a9c346d5c93ae3ce339412b90a0b8f83f94ec6baa24e30c	1102

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

Init transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	6093	10.80	3.35	0.53
2	6298	13.26	4.11	0.56
3	6495	15.71	4.88	0.60
5	6902	20.16	6.24	0.66
10	7904	31.40	9.68	0.82
40	13936	98.36	30.21	1.78

Commit transaction costs

This uses ada-only outputs for better comparability.

UTxO	Tx size	% max Mem	% max CPU	Min fee ₳
1	563	2.44	1.16	0.20
2	740	3.38	1.73	0.22
3	916	4.36	2.33	0.24
5	1279	6.41	3.60	0.28
10	2176	12.13	7.25	0.40
54	10065	98.61	68.52	1.88

CollectCom transaction costs

Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
1	57	525	26.44	7.58	0.44
2	114	636	34.89	9.98	0.53
3	170	747	45.59	12.92	0.64
4	227	858	51.82	14.82	0.71
5	283	969	61.97	17.60	0.82
6	338	1081	75.13	21.17	0.96
7	396	1192	82.21	23.25	1.03
8	448	1303	94.36	26.65	1.16

Cost of Increment Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	1748	24.02	7.84	0.48
2	1933	26.61	9.37	0.52
3	2139	29.66	11.04	0.56
5	2455	33.52	13.66	0.63
10	3094	41.88	19.55	0.77
38	7348	97.87	56.39	1.67

Cost of Decrement Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	610	23.99	7.61	0.43
2	821	26.46	8.97	0.46
3	865	27.22	9.83	0.48
5	1242	32.91	12.73	0.56
10	1829	38.66	17.63	0.67
39	6270	98.51	53.45	1.61

Close transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	681	29.19	9.21	0.48
2	810	32.81	10.92	0.53
3	982	35.44	12.48	0.57
5	1290	37.22	14.44	0.61
10	1991	50.34	21.86	0.80
35	5716	99.11	54.39	1.59

Contest transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	629	35.29	10.70	0.54
2	823	38.19	12.34	0.58
3	960	40.32	13.64	0.62
5	1207	44.59	16.24	0.68
10	2073	58.02	24.01	0.88
27	4495	98.00	47.66	1.48

Abort transaction costs

There is some variation due to the random mixture of initial and already committed outputs.

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	5972	28.33	9.33	0.71
2	6116	37.52	12.36	0.81
3	6310	47.80	15.80	0.93
4	6389	57.34	18.92	1.03
5	6356	60.17	19.75	1.06
6	6593	72.08	23.76	1.19
7	6641	78.64	25.80	1.26
8	6913	96.19	31.80	1.46

FanOut transaction costs

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 ₳
10	0	0	6092	19.20	6.31	0.62
10	10	569	6430	40.04	14.41	0.86
10	20	1138	6769	62.72	23.14	1.12
10	30	1709	7113	84.03	31.40	1.37
10	36	2050	7315	97.27	36.52	1.52

End-to-end benchmark results

This page is intended to collect the latest end-to-end benchmark results produced by Hydra's continuous integration (CI) system from the latest master code.

Please note that these results are approximate as they are currently produced from limited cloud VMs and not controlled hardware. Rather than focusing on the absolute results, the emphasis should be on relative results, such as how the timings for a scenario evolve as the code changes.

Generated at 2025-04-02 12:28:52.506188688 UTC

Baseline Scenario

Number of nodes	1
Number of txs	300
Avg. Confirmation Time (ms)	4.698691970
P99	11.233135149999995ms
P95	5.25166115ms
P50	4.2302990000000005ms
Number of Invalid txs	0

Memory data

Time	Used	Free
2025-04-02 12:27:36.928182985 UTC	925M	6240M
2025-04-02 12:27:41.927942659 UTC	1039M	6095M
2025-04-02 12:27:46.928023189 UTC	1040M	6094M
2025-04-02 12:27:51.927929422 UTC	1036M	6097M
2025-04-02 12:27:56.927894249 UTC	1036M	6097M
2025-04-02 12:28:01.927917248 UTC	1037M	6095M

Three local nodes

Number of nodes	3
Number of txs	900
Avg. Confirmation Time (ms)	28.716562657
P99	41.735164539999985ms
P95	38.37488275ms
P50	27.630542ms
Number of Invalid txs	0

Memory data

Time	Used	Free
2025-04-02 12:28:15.502637402 UTC	958M	6184M
2025-04-02 12:28:20.504687964 UTC	1214M	5924M
2025-04-02 12:28:25.503844147 UTC	1266M	5808M
2025-04-02 12:28:30.502693712 UTC	1272M	5758M
2025-04-02 12:28:35.502728172 UTC	1277M	5753M
2025-04-02 12:28:40.502882716 UTC	1278M	5752M
2025-04-02 12:28:45.502696098 UTC	1277M	5752M
2025-04-02 12:28:50.502981607 UTC	1278M	5750M

[noonio]

Looks great; happy to merge with some minor changes to the docs.

Thanks!