Signals

Preview — Ranvier is pre-release; its APIs may change.

The write path is the most frequently executed path in the library. These benchmarks measure reads, writes and the equality cutoff on a single signal. See Benchmarks for configuration, environment and caveats.

SignalBenchmarks

One int signal observed by Observers memos (0, 1, 8 or 64).

Method	What it measures
`Read`	A tracked read with no computation running: the read an outside caller makes.
`Peek`	An untracked read. Compared with `Read`, it shows the cost of the tracking check.
`Write`	A write that changes the value, so every observer is notified. With 0 observers it is the floor for a write.
`WriteCutoff`	A write of an equal value. The equality cutoff stops it, so nothing downstream is touched.
`WriteAndPropagate`	A write followed by reading every observer back, so it includes the recomputations the write caused. The difference from `Write` is the cost of propagation.

Recorded 2026-09-28. Source: Ranvier.Benchmarks.Signals.SignalBenchmarks at commit d87920f.

Method	Observers	Mean	Error	StdDev	Op/s	Allocated
Read	0	0.2294 ns	0.0173 ns	0.0153 ns	4,358,414,858.0	-
Peek	0	0.2074 ns	0.0066 ns	0.0058 ns	4,822,342,533.3	-
Write	0	1.6874 ns	0.0293 ns	0.0245 ns	592,630,946.9	-
WriteCutoff	0	1.0102 ns	0.0246 ns	0.0231 ns	989,944,159.6	-
WriteAndPropagate	0	1.8208 ns	0.0289 ns	0.0256 ns	549,214,973.6	-
Read	1	0.2466 ns	0.0235 ns	0.0220 ns	4,054,727,400.7	-
Peek	1	0.2018 ns	0.0052 ns	0.0043 ns	4,954,368,076.7	-
Write	1	2.1688 ns	0.0399 ns	0.0354 ns	461,088,285.7	-
WriteCutoff	1	1.0125 ns	0.0307 ns	0.0272 ns	987,618,863.1	-
WriteAndPropagate	1	3.0830 ns	0.0128 ns	0.0107 ns	324,360,362.2	-
Read	8	0.2270 ns	0.0080 ns	0.0075 ns	4,404,951,053.6	-
Peek	8	0.2131 ns	0.0111 ns	0.0104 ns	4,692,999,479.0	-
Write	8	6.3612 ns	0.0702 ns	0.0657 ns	157,203,455.5	-
WriteCutoff	8	1.0141 ns	0.0253 ns	0.0224 ns	986,111,038.4	-
WriteAndPropagate	8	7.9569 ns	0.1068 ns	0.0947 ns	125,676,794.1	-
Read	64	0.2227 ns	0.0081 ns	0.0072 ns	4,490,411,024.6	-
Peek	64	0.2069 ns	0.0068 ns	0.0060 ns	4,832,182,570.0	-
Write	64	47.8819 ns	0.3217 ns	0.2686 ns	20,884,713.1	-
WriteCutoff	64	1.0090 ns	0.0231 ns	0.0193 ns	991,112,303.3	-
WriteAndPropagate	64	57.4765 ns	0.3814 ns	0.3381 ns	17,398,409.8	-

Thread affinity

SignalBenchmarks runs each case under every ThreadAffinity, set by Affinity:

`Affinity`	Check on a write's entry
`Guarded`	The default. A thread-id comparison against the graph's owner thread.
`Unchecked`	None.
`Serialised`	Entry into the graph by the calling thread, which must run on the synchronisation context the graph was constructed on. A second thread entering at once raises.

The table above predates the parameter and shows Guarded only.

The counter scenario chain-affinity writes the head of a four-memo chain and reads the tail under each affinity. Figures are retired instructions per operation at commit e13f159, .NET 10 with tiered compilation and PGO off (see Instruction counts):

Affinity	instr/op	Library counters/op
`Guarded`	2,179	MemoRecomputes 4
`Unchecked`	2,177	MemoRecomputes 4
`Serialised`	2,516	MemoRecomputes 4

Unchecked costs the same as Guarded: the thread-id comparison is within run-to-run noise. Serialised costs about 340 more instructions per write and read of the chain, about 15 % over Guarded. The BenchmarkDotNet timing cases for each affinity are in the suite for local runs (dotnet run --project bench/Ranvier.Benchmarks -c Release -- --filter "*SignalBenchmarks*") and have no published figure yet. The full report is e13f159.md.

EqualityBenchmarks

A reference-typed signal written with a cutoff by identity (the default) or by structural comparison (StructuralPolicy). The gap between the rows is the cost of choosing structural equality.

Method	What it measures
`IdentityCutoff`	Baseline. A write stopped by identity comparison.
`StructuralCutoff`	A write of a structurally equal value, stopped by a deep comparison.
`StructuralWrite`	A write of a structurally different value under `StructuralPolicy`.

Recorded 2026-09-28. Source: Ranvier.Benchmarks.Signals.EqualityBenchmarks at commit d87920f.

Method	Mean	Error	StdDev	Op/s	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
IdentityCutoff	1.391 ns	0.0202 ns	0.0179 ns	718,789,638.3	baseline		-	-	NA
StructuralCutoff	5.743 ns	0.1000 ns	0.0886 ns	174,110,032.6	4.13x slower	0.08x	-	-	NA
StructuralWrite	6.208 ns	0.0609 ns	0.0540 ns	161,091,273.4	4.46x slower	0.07x	0.0019	32 B	NA

The Ratio and Alloc Ratio columns, where present, compare each method with the baseline method of the same class on the same run. They describe the relative cost of two operations inside Ranvier, not a comparison with any other library.

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