Rust

fix: Don't block heartbeat when all slots acquired #210

Job	Run time
check linux workspace	3m 5s
test linux balista	7m 31s
macos test	10m 47s
windows test	14m 23s
linux build test	4m 20s
test linux crates	7m 35s
Lint	35s
Clippy (amd64, stable)	4m 23s
verify benchmark results (amd64)	17m 30s
Check Cargo.toml formatting (amd64, stable)	1m 5s
cargo doc	3m 59s
	1h 15m 13s

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