iotaledger / iota / 34298612439

70%

Build Type

push

github

Committed by web-flow

Commit Message

feat(starfish): fetch missing ancestors without gap in live syncrhonizer after a short wait (#12844)

# Description of change

Reduces the header synchronizer's load on the live path, which on a
lagging validator takes over header intake from the block streams and
keeps the node behind.

- Live requests carry no frontier, so the peer returns only the
requested headers. The gap-fill of one header per round below them
duplicated what the block streams already deliver; on a lagging node 95%
of those headers arrived already known. The periodic synchronizer keeps
its frontier and gap-fill.
- Before sending, the live path waits two block delays and drops every
ref whose header arrived over the streams in the meantime. A request
with nothing left is not sent and records no responsiveness sample.
- The streamed-header digest filter is owned by the header synchronizer
and shared with the authority service, so the live path can read it.
- Two counters: missing headers resolved while waiting, and live
requests skipped entirely.

No wire change: an empty frontier already means "requested headers only"
for the responder, so old and new peers behave the same.

## Links to any relevant issues

Fixes #12843

## How the change has been tested

- [x] Basic tests (linting, compilation, formatting, unit/integration
tests)
- [x] Patch-specific tests (correctness, functionality coverage)
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] I have checked that new and existing unit tests pass locally with
my changes

Coverage Stats

229 of 230 new or added lines in 3 files covered. (99.57%)

3989 existing lines in 75 files now uncovered.

179724 of 257342 relevant lines covered (69.84%)

453308.8 hits per line