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rustfs/crates/ecstore/AGENTS.md
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2026-08-22 08:19:53 +08:00

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# ECStore Crate Instructions
Applies to `crates/ecstore/`.
## Data Durability and Integrity
- Do not weaken quorum checks, bitrot checks, or metadata validation paths.
- Treat any change affecting read/write/repair correctness as high risk and test accordingly.
- Prefer explicit failure over silent data corruption or implicit success.
## Performance-Critical Paths
- Be careful with allocations and locking in hot paths.
- Keep network and disk operations async-friendly; avoid introducing unnecessary blocking.
- Benchmark-sensitive changes should include measurable rationale.
## Allocation Discipline in Hot Paths
- Do not implement `Clone` on structs with >5 heap-allocated fields without considering `Arc` for heavy fields.
- Before cloning a struct in a loop or per-request path, check if a reference or `Cow` would suffice.
- When a struct contains a large buffer (e.g., erasure coding block), wrap it in `Arc` and pass by reference rather than cloning.
- Use `&str` and `Cow<str>` instead of `String` for temporary computations (header parsing, signature building, path manipulation).
- Use `HashMap::with_capacity()` / `Vec::with_capacity()` when the size is known or estimable.
## Lock Ordering
- When a function acquires multiple locks, document the acquisition order in a comment.
- Never acquire the same set of locks in different orders across code paths — this is a deadlock.
- Prefer `compare_exchange` loops over load-then-store for concurrent counters.
## Recursion Safety
- Recursive tree traversals (cache trees, directory walks) must have a depth limit or use iterative traversal with an explicit `Vec` stack.
- `flatten()`, `delete_recursive()`, `copy_with_children()`, `total_children_rec()`, `mark()` — all must handle deep or corrupted trees safely.
## Dead Code
- Do not add `#![allow(dead_code)]` at the crate root. If code is unused, remove it or gate it behind a feature flag.
- Each `#[allow(dead_code)]` annotation must have a comment explaining why the code is kept.
## Cross-Module Coordination
- Validate behavior impacts on:
- `rustfs/src/storage/`
- `crates/filemeta/`
- `crates/heal/`
- `crates/checksums/`
## Suggested Validation
- `cargo test -p rustfs-ecstore`