Merge iterator - Rust

K-way merge of sorted streams via a min-heap of stream heads. next() is one heap-pop and one heap-push.

Part of the submillisecond.com cookbook. Zero external dependencies; std only.

Install

[dependencies]
subms-merge-iterator = "0.10"

# or with the opt-in cursor and key-resolution variants
subms-merge-iterator = { version = "0.10", features = ["seek-to", "tombstones"] }

Quickstart

cargo test --all-features
cargo run --example sample_app --features full

Public API

Base, always available:

MergeIterator::new(streams) - ascending k-way merge; implements Iterator.
peek(), live_streams(), num_streams() - cursor introspection.

Behind Cargo features (full turns on all five):

seek-to - SeekableMergeIterator with seek(target), set_upper_bound(hi) (exclusive), clear_upper_bound().
reverse - ReverseMergeIterator over descending sources, with seek_for_prev(target), set_lower_bound(lo) (inclusive), clear_lower_bound().
tombstones - TombstoneMergeIterator / TombstoneEntry; latest-source-wins with delete markers.
dedup - DedupMergeIterator / DedupEntry; one entry per distinct key, latest-source-wins.
priority - PriorityMergeIterator / PriorityEntry / PrioritySource; explicit per-source precedence.

The harness feature pulls in subms for the SubMsRecipe impl and the bench targets.

Files

src/lib.rs - the base merge; src/features/ - one module per opt-in feature.
src/*_tests.rs - colocated unit tests; tests/sub_millisecond_bench.rs - the asserted p99 gate.
examples/sample_app.rs - a miniature market-data store read through every variant.
examples/perf_main.rs, examples/perf_features.rs - bench entries (behind harness).

License