fix(valgrind): install libc6-dbg during valgrind setup

[not-matthias]

This takes around 10 seconds, so it shouldn't be an issue that it's not cached + prevents complexities of cache invalidation

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 7 untouched benchmarks

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_{Comparing cod-2770-unresolved-symbol-in-exec-cli-simulation-benchmarks (2cab37a) with main (9793aaf)}

[greptile-apps]

Greptile Summary

Installs libc6-dbg during valgrind setup so that GitHub runners have the libc debug symbols Valgrind needs to trace libc functions correctly. The package install is intentionally left uncached per the PR description.

• apt::install(system_info, &[\"libc6-dbg\"]) is appended after apt::install_cached returns; because it sits outside the caching gate, it runs unconditionally on every install_valgrind call — including runs where valgrind is already cached and apt::install_cached exits early.
• apt::install always executes apt-get update first, so cached CI runs will pay the ~10 s overhead on every invocation rather than only on the initial install.

Confidence Score: 3/5

The change adds repeated apt-get update overhead to every CI run where valgrind is already cached, negating caching benefits.

The libc6-dbg install sits outside the caching gate and will run apt-get update plus an install attempt on every CI invocation, including those that skip the valgrind installation entirely via the early-return path in apt::install_cached.

src/executor/valgrind/setup.rs — specifically the placement of the apt::install call relative to the apt::install_cached early-return logic.

Important Files Changed

Filename	Overview
src/executor/valgrind/setup.rs	Adds libc6-dbg installation after the cached valgrind setup; the call is unconditional and bypasses the caching gate, causing apt-get update + install to run on every invocation even when valgrind is already cached.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[install_valgrind called] --> B{is_valgrind_installed?}
    B -- yes --> C[apt::install_cached returns Ok early]
    B -- no --> D[Try restore from cache]
    D --> E{restored & installed?}
    E -- yes --> F[apt::install_cached returns Ok]
    E -- no --> G[Download valgrind .deb + apt-get update + install]
    G --> H[Save packages to cache]
    H --> I[apt::install_cached returns Ok]
    C --> J[apt::install libc6-dbg runs EVERY time]
    F --> J
    I --> J
    J --> K[install_valgrind returns Ok]

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[greptile-apps]

libc6-dbg installed unconditionally, bypassing the cache gate

apt::install_cached exits early (return Ok(())) when valgrind is already installed, but the new apt::install call for libc6-dbg sits outside that gate and runs on every install_valgrind invocation. This means every CI run where valgrind is cached will still execute apt-get update followed by an install attempt for libc6-dbg — adding the ~10 s overhead even when nothing needs to be installed. Including libc6-dbg inside the install_packages closure (alongside the valgrind .deb) would keep it under the same caching and idempotency logic, or at minimum a dpkg -s libc6-dbg check could guard the call.

[greptile-apps]

The comment "Only install for supported systems" implies a silent no-op on incompatible systems, but apt::install actually propagates an error (bail!) when the system is incompatible. While install_valgrind is only reached on supported systems today, the comment is misleading about the runtime behaviour.

Suggested change

	// Install libc debug symbols, as Github runners by default do not
	// include them. Only install for supported systems.
	apt::install(system_info, &["libc6-dbg"])?;
	// Install libc debug symbols, as GitHub runners do not include them by
	// default. `apt::install` will error on unsupported systems, but this
	// function is only reachable when `is_codspeed_valgrind_installation_supported`
	// is true, so only compatible Linux distros reach this point.
	apt::install(system_info, &["libc6-dbg"])?;

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[GuillaumeLagrange]

Part of the cache in the action is to avoid having to do sudo apt update when not required, which can take quite a lot of time.

We should cache the output of libc dbg, because it can in practice ad 30 sec to 1 min to ci runs.

apt.rs already exposes the cache helper it should work transparently