$ show scylladb/seastar
Seastar is a high-performance C++ asynchronous framework built on a shared-nothing, reactor-based architecture. It provides core primitives like futures/promises, coroutine support, per-CPU sharding, and a sophisticated I/O scheduler with fair queuing and token-bucket throttling. The framework includes a production-grade networking stack (TCP, UDP, TLS, HTTP, WebSocket, RPC), a custom memory allocator, comprehensive metrics (Prometheus, collectd), and extensive testing/benchmarking infrastructure. Seastar is used by real-world systems such as ScyllaDB, Redpanda, and Ceph Crimson. The codebase is mature, but exhibits some technical debt in the form of deprecated API usage, platform-specific workarounds, and a few license inconsistencies. Overall, it represents a strong example of systems-level C++ engineering with reusable algorithmic components and a well-documented architecture.
The LLM identified 3 files worth highlighting for reuse:
Provides a `defer` function that creates a scope guard object which invokes a user-supplied callable when the object is destroyed. This is a generic RAII pattern useful for cleanup, rollback, and resource management in any C++ project. The implementation is header-only, dependency-lean (only uses standard utilities), and can be extracted with minimal changes.
Implements a shared token bucket algorithm with support for burst limits, borrow, and timing. This is a reusable rate-limiting primitive suitable for throttling network connections, disk I/O, or any resource access. The implementation is header-only and uses only standard library types, making it easily portable to other projects.
A standalone Python script that tunes Linux system performance for low-latency, high-throughput workloads. It configures IRQ affinity, CPU isolation, network RPS/XPS, NUMA-aware interrupt distribution, and I/O scheduler settings. The script uses pyudev, psutil, and hwloc and can be reused independently of the Seastar framework.