Elamur Groupantsvfs-snapbench
The groupant beside vfs/examples/snapbench.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | syntax.json |
| composition | partial | composition |
| cost | partial | Cost |
| descriptant | present | descriptant |
| invariant | partial | Invariant |
| tests | executed bounded checks | tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
iteration_count | iteration_count | partial source derived model | iteration_count |
format_partition | format_partition | partial source derived model | format_partition |
benchmark_scope | benchmark_scope | partial source derived model | benchmark_scope |
allocation_domain | allocation_domain | partial source derived model | allocation_domain |
Model text
descriptant
vfs-snapbench
Timing helpers and unexecuted snapshot workload.
Prospective epoch
2026-10-31: source reviewed before edits; prospective review retained under $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31/prospective.md. Predicted order/cost: per_op O(nclosure cost), main allocation O(N1024+64MiB), repeated shared-buffer edits copy64MiB; main intentionally not executed.
Observation epoch
Bounded actual calls and compiled negative controls are recorded in tests.md. Production behavior bytes unchanged; only focused test blocks added. Snapshot constant-time wording is conditional on cwd and destruction; recursive operations may partially commit.
Unsupported approximants
No executable percentage surrogate is claimed for these categorical/state/effect observations. Future 1%,2%,5%,10% require a useful metric, explicit domain and exact reference.
approximant
Forward relation
Timing helpers and unexecuted snapshot workload.
per_op(n,f) invokes f exactly n times then divides elapsed seconds by n; fmt chooses ns if s<1e-6, microseconds if s<1e-3 else ms. Main scales1000/10000/100000 files plus64MiB and compares snapshot,restore,write,dump timings.
Domain: bounded inputs with available allocation and nonoverflowing counters unless checked explicitly. The relation is partial and source-derived.
composition
Composition
Timing helpers and unexecuted snapshot workload. Shared state and order: per_op(n,f) invokes f exactly n times then divides elapsed seconds by n; fmt chooses ns if s<1e-6, microseconds if s<1e-3 else ms. Main scales1000/10000/100000 files plus64MiB and compares snapshot,restore,write,dump timings.
Scoped children project this same source. Their domains and effects remain conditional; source execution connects these clauses rather than independently proving their wiring. For n>0 bounded helper elapsed is finite nonnegative; timing is nondeterministic. fmt boundaries use strict less-than. n0 remains undefined useful average (infinite/NaN possible).
models
Typed source models
Source-bound partial relations; no universal finite-test proof.
behavior_complement
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: At exactly1e-6 output cannot be ns, at1e-3 cannot be microseconds. Helper tests do not validate benchmark speed claims.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
reverse_reconstruction
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Formatted rounded duration admits intervals and cannot reconstruct raw clock or workload timing distribution. Per-op mean admits many individual duration sequences.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
iteration_count
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: n3 calls closure3 times; n0 invokes none but divides by0, outside useful timing domain.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
format_partition
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Strict thresholds at1e-6 and1e-3; rounding precision differs by branch.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
benchmark_scope
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: black_box prevents easy elimination but timings include closure/drop effects; no portable complexity measurement follows.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
allocation_domain
Subject: vfs-snapbench. Domain: Timing helpers and unexecuted snapshot workload. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Largest main fixture and million iterations skipped; only three no-allocation closure invocations tested.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
tests
Checks and limitations
Exact named observations: wave31::bounded_helpers.
Fresh receipts: $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31; run.sh retains four profile/repetition sets with raw logs and numeric statuses. native-commands.json and source-test-map.json disambiguate targets. Compiled mutations and exact restoration are separately retained in mutation-summary.json.
These finite observations are not semantic completeness. Source syntax generated twice and compared byte-for-byte. Host effects are limited to owned TMPDIR fixtures. Existing absolute_paths_never_reach_the_host and open_modes are skipped; snapbench main is skipped. Standalone helpers/reexports are only observed through named callers or representation checks; RealFs effect methods unexecuted.
invariant-and-cost
Invariant and cost
Invariant
For n>0 bounded helper elapsed is finite nonnegative; timing is nondeterministic. fmt boundaries use strict less-than. n0 remains undefined useful average (infinite/NaN possible).
Cost
per_op O(nclosure cost), main allocation O(N1024+64MiB), repeated shared-buffer edits copy64MiB; main intentionally not executed.
No timing or numerical error guarantee is inferred from finite tests.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/vfs/examples/snapbench.rs.groupant/