perf: pre-size setup dispatch tables to FastMockInteractions member count

[vbreuss]

The outer table started at size memberId+1, forcing a realloc + Array.Copy when a later setup targeted a higher-numbered member. The generator already knows the total member count and exposes it via FastMockInteractions.Buffers.Length, so use that as the initial size on first allocation. Subsequent setups never need to grow the outer table.

Saves one outer-table allocation plus the Array.Copy per fresh mock when setups touch multiple members. Applies to the method, indexer, property, and event dispatch tables.

[Copilot]

Pull request overview

This PR improves setup registration performance in MockRegistry by pre-sizing the per-member setup dispatch tables using the generator-known mocked member count (via FastMockInteractions.Buffers.Length), avoiding a first-time resize/copy when setups target higher-numbered member ids.

Changes:

• Add a GetMemberCountHint() helper that returns FastMockInteractions.Buffers.Length when available.
• Use the hint on first allocation of method/indexer/property/event setup dispatch tables to reduce reallocations and Array.Copy.

[github-actions]

Test Results

    24 files  ±0      24 suites  ±0   10m 14s ⏱️ + 1m 25s
 4 086 tests ±0   4 084 ✅ ±0  2 💤 ±0  0 ❌ ±0 
26 388 runs  ±0  26 384 ✅ ±0  4 💤 ±0  0 ❌ ±0 

Results for commit b3be8a2. ± Comparison against base commit 0bb1ef9.

♻️ This comment has been updated with latest results.

[github-actions]

🚀 Benchmark Results

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

CreateMock	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	65.98 ns	0.212 ns	0.199 ns	1.03	440 B	1.00
Mockolate	64.23 ns	0.606 ns	0.537 ns	1.00	440 B	1.00
Imposter	295.56 ns	9.685 ns	9.059 ns	4.60	2248 B	5.11
TUnitMocks	41.42 ns	1.265 ns	1.184 ns	0.64	224 B	0.51
Moq	1,518.21 ns	13.545 ns	12.670 ns	23.64	2096 B	4.76
NSubstitute	2,113.25 ns	43.452 ns	40.645 ns	32.90	5048 B	11.47
FakeItEasy	1,923.36 ns	57.262 ns	53.563 ns	29.95	2763 B	6.28

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

Intel Xeon Platinum 8370C CPU 2.80GHz (Max: 3.39GHz), 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v4
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Event	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	353.6 ns	7.98 ns	7.46 ns	1.05	1.78 KB	1.00
Mockolate	336.5 ns	11.03 ns	10.32 ns	1.00	1.78 KB	1.00
Imposter	1,400.3 ns	21.72 ns	20.32 ns	4.16	8.8 KB	4.94
TUnitMocks	203.0 ns	2.94 ns	2.61 ns	0.60	1.37 KB	0.77
Moq	14,813.6 ns	34.33 ns	30.43 ns	44.06	12.51 KB	7.02
NSubstitute	5,830.1 ns	76.21 ns	67.56 ns	17.34	9.05 KB	5.08
FakeItEasy	189,429.1 ns	2,088.67 ns	1,851.55 ns	563.43	15.26 KB	8.57

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Indexer	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	968.8 ns	16.01 ns	14.98 ns	0.99	3.81 KB	1.00
Mockolate	1	977.3 ns	6.82 ns	6.04 ns	1.00	3.82 KB	1.00
Imposter	1	962.7 ns	5.72 ns	5.07 ns	0.99	5.16 KB	1.35
Moq	1	216,126.1 ns	857.29 ns	759.96 ns	221.17	20.37 KB	5.33
NSubstitute	1	9,314.8 ns	19.62 ns	17.39 ns	9.53	12.78 KB	3.35
FakeItEasy	1	12,302.3 ns	24.06 ns	20.09 ns	12.59	13.63 KB	3.57
baseline*	10	2,572.8 ns	14.48 ns	13.54 ns	1.03	4.87 KB	1.00
Mockolate	10	2,497.7 ns	9.17 ns	8.13 ns	1.00	4.88 KB	1.00
Imposter	10	2,181.2 ns	6.40 ns	5.99 ns	0.87	7.97 KB	1.63
Moq	10	229,335.7 ns	398.33 ns	353.10 ns	91.82	29.89 KB	6.13
NSubstitute	10	22,896.7 ns	52.82 ns	46.82 ns	9.17	25.58 KB	5.25
FakeItEasy	10	25,367.6 ns	87.21 ns	77.31 ns	10.16	32.97 KB	6.76

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 9V74 2.60GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	395.2 ns	4.18 ns	3.91 ns	1.04	2.04 KB	1.00
Mockolate	1	381.7 ns	3.06 ns	2.86 ns	1.00	2.04 KB	1.00
Imposter	1	533.1 ns	4.31 ns	3.60 ns	1.40	4.04 KB	1.98
TUnitMocks	1	673.1 ns	9.40 ns	8.79 ns	1.76	2.9 KB	1.42
Moq	1	133,764.0 ns	860.25 ns	762.59 ns	350.44	14.59 KB	7.15
NSubstitute	1	5,357.5 ns	97.88 ns	91.56 ns	14.04	9.12 KB	4.47
FakeItEasy	1	5,863.7 ns	105.55 ns	98.73 ns	15.36	8.27 KB	4.06
baseline*	10	819.0 ns	3.54 ns	3.31 ns	1.26	2.25 KB	1.00
Mockolate	10	650.8 ns	6.59 ns	6.17 ns	1.00	2.25 KB	1.00
Imposter	10	1,123.1 ns	25.75 ns	24.08 ns	1.73	5.52 KB	2.45
TUnitMocks	10	1,783.6 ns	24.11 ns	21.37 ns	2.74	4.49 KB	2.00
Moq	10	138,055.7 ns	1,021.38 ns	955.40 ns	212.14	18.48 KB	8.21
NSubstitute	10	8,018.3 ns	99.75 ns	93.31 ns	12.32	12.07 KB	5.37
FakeItEasy	10	9,077.6 ns	167.37 ns	156.56 ns	13.95	15.65 KB	6.95

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Property	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	613.2 ns	7.02 ns	6.57 ns	1.01	2.46 KB	1.00
Mockolate	1	609.9 ns	13.33 ns	12.47 ns	1.00	2.47 KB	1.00
Imposter	1	559.1 ns	15.87 ns	14.85 ns	0.92	3.13 KB	1.27
TUnitMocks	1	817.3 ns	8.44 ns	7.90 ns	1.34	2.51 KB	1.02
Moq	1	12,299.7 ns	87.10 ns	77.22 ns	20.17	10.39 KB	4.21
NSubstitute	1	8,058.8 ns	20.54 ns	18.20 ns	13.22	11.45 KB	4.64
FakeItEasy	1	8,829.5 ns	87.47 ns	81.82 ns	14.48	11.24 KB	4.55
baseline*	10	1,175.3 ns	5.59 ns	5.23 ns	1.02	2.95 KB	1.00
Mockolate	10	1,147.0 ns	19.75 ns	18.47 ns	1.00	2.96 KB	1.00
Imposter	10	1,279.9 ns	19.97 ns	18.68 ns	1.12	4.67 KB	1.58
TUnitMocks	10	2,317.3 ns	13.79 ns	12.22 ns	2.02	4.66 KB	1.58
Moq	10	19,657.7 ns	41.97 ns	37.21 ns	17.14	18.28 KB	6.17
NSubstitute	10	18,508.7 ns	82.95 ns	77.59 ns	16.14	21.08 KB	7.12
FakeItEasy	10	20,741.0 ns	155.80 ns	138.11 ns	18.09	30.81 KB	10.40

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Callback	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	255.1 ns	3.55 ns	3.32 ns	0.73	1.68 KB	1.00
Mockolate	347.7 ns	7.24 ns	6.04 ns	1.00	1.68 KB	1.00
Imposter	433.1 ns	3.17 ns	2.97 ns	1.25	2.38 KB	1.42
TUnitMocks	615.7 ns	2.06 ns	1.93 ns	1.77	2.63 KB	1.56
Moq	98,369.4 ns	211.64 ns	187.61 ns	282.97	8.88 KB	5.29
NSubstitute	4,491.6 ns	34.24 ns	32.03 ns	12.92	7.74 KB	4.61
FakeItEasy	4,805.4 ns	42.05 ns	37.28 ns	13.82	6.81 KB	4.05

baseline* rows show the corresponding Mockolate benchmark from the most recent successful main branch build with results, for regression comparison.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
93.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

This is addressed in release v3.2.0.