laminar-core

Core streaming engine for LaminarDB -- reactor, operators, state stores, and streaming infrastructure.

Overview

Ring 0 crate. Everything here targets sub-microsecond execution with zero heap allocations on the hot path.

Key Modules

Module	Purpose
`reactor`	Single-threaded event loop, CPU-pinned
`operator`	Windows (tumbling, sliding, hopping, session), joins (stream, ASOF, temporal, lookup), changelog, lag/lead, ranking
`state`	`StateStore` trait, `InMemoryStateStore` (AHashMap), `ChangelogAwareStore` wrapper
`time`	Event time processing, watermarks (partitioned, keyed, alignment groups)
`streaming`	Ring buffer, SPSC/MPSC channels, source/sink abstractions, checkpoint manager
`dag`	DAG pipeline topology, multicast routing, executor, checkpointing
`subscription`	Reactive push-based subscriptions: events, notifications, registry, dispatcher
`tpc`	Thread-per-core runtime: SPSC queues, key router, core handles, backpressure
`sink`	Exactly-once transactional sink, epoch adapter
`mv`	Cascading materialized views
`compiler`	JIT compiler: EventRow, Cranelift expressions, pipeline extraction/compilation, cache
`alloc`	Zero-allocation enforcement (bump/arena allocators)
`numa`	NUMA-aware memory allocation
`io_uring`	io_uring integration, three-ring I/O architecture
`budget`	Task budget enforcement
`checkpoint`	Distributed checkpoint barrier protocol, barrier alignment
`lookup`	Lookup table trait, predicate types, foyer caches (memory + hybrid)
`aggregation`	Cross-partition lock-free HashMap (papaya)
`error_codes`	Structured `LDB-NNNN` error code registry and zero-alloc `HotPathError`
`detect`	Platform detection utilities
`xdp`	Linux eBPF/XDP network optimization
`delta`	Distributed mode: discovery (gossip, Kafka), Raft consensus, partition ownership, gRPC RPC

Feature Flags

Flag	Purpose
`jit`	Cranelift JIT compilation for Ring 0 query execution
`allocation-tracking`	Panic on heap allocation in marked sections
`io-uring`	Linux 5.10+ io_uring integration
`hwloc`	Enhanced NUMA topology discovery (hwlocality)
`xdp`	Linux eBPF/XDP network optimization (libbpf-rs)
`dag-metrics`	Per-event DAG executor metrics (adds ~5-10ns/event overhead)
`delta`	Distributed mode (tonic, openraft, chitchat, prost)

Ring Placement

All code in this crate must:

Make zero heap allocations
Use no locks (SPSC queues for communication)
Avoid system calls on the fast path
Stay within task budget limits

Key Abstractions

StateStore Trait

pub trait StateStore: Send {
    fn get(&self, key: &[u8]) -> Option<&[u8]>;
    fn put(&mut self, key: &[u8], value: &[u8]);
    fn delete(&mut self, key: &[u8]);
    fn prefix_scan(&self, prefix: &[u8]) -> impl Iterator<Item = (&[u8], &[u8])>;
}

Reactor

Single-threaded event loop that pulls batches from sources, runs them through the operator DAG, and emits results. CPU-pinned via the thread-per-core runtime.

Operator Types

Stateless: map, filter, project
Windowed: tumbling, sliding, hopping, session (with merge detection)
Join: stream-stream (time-bounded), ASOF (point-in-time), temporal, lookup
Analytics: LAG/LEAD, ROW_NUMBER/RANK/DENSE_RANK
Changelog: Z-set retraction (+1 insert, -1 retract)

Benchmarks

cargo bench -p laminar-core --bench state_bench       # State lookup latency
cargo bench -p laminar-core --bench throughput_bench   # Throughput per core
cargo bench -p laminar-core --bench latency_bench      # p99 latency
cargo bench -p laminar-core --bench window_bench       # Window operations
cargo bench -p laminar-core --bench dag_bench          # DAG pipeline
cargo bench -p laminar-core --bench join_bench         # Join throughput
cargo bench -p laminar-core --bench lookup_join_bench  # Lookup join throughput
cargo bench -p laminar-core --bench cache_bench        # foyer cache hit/miss
cargo bench -p laminar-core --bench compiler_bench     # JIT compilation
cargo bench -p laminar-core --bench streaming_bench    # Streaming channels
cargo bench -p laminar-core --bench subscription_bench # Subscription dispatch
cargo bench -p laminar-core --bench reactor_bench      # Reactor loop
cargo bench -p laminar-core --bench tpc_bench          # Thread-per-core
cargo bench -p laminar-core --bench checkpoint_bench   # Checkpoint cycle
cargo bench -p laminar-core --bench delta_checkpoint_bench  # Delta checkpoint
cargo bench -p laminar-core --bench io_uring_bench     # io_uring operations
cargo bench -p laminar-core --bench dag_stress         # DAG stress test

Related Crates

laminar-sql -- SQL parser that produces operator configurations
laminar-storage -- WAL and checkpointing that consumes changelog entries
laminar-db -- Database facade that orchestrates the reactor

laminar-core 0.18.0