Libraries Index

Source: docs/libraries/README.md in the main repository.

C++26 Systems Stack — Library Catalog

Architecture-oriented notes for each component wired into this repository.
Each guide covers role in a systems stack, when to choose it, integration in this project, and how it is validated.

Catalog

Guide	Package	Primary responsibility
Asio	asio (standalone) / Boost.Asio	Async I/O, timers, executors
Beast	Boost.Beast	HTTP and WebSocket on Asio
Taskflow	Taskflow	Explicit task graphs and pipelines
oneTBB	oneTBB	Data-parallel algorithms and concurrent structures
stdexec	NVIDIA stdexec	P2300 senders/receivers composition
simdjson	simdjson	High-throughput JSON parsing
protobuf + gRPC	protobuf, gRPC	Schemas and RPC services
Folly	Folly (optional)	Service utilities, F14, futures
HPX	HPX (optional)	Distributed/local parallel runtime

Foundation packages (covered in test_libs / integration binary)

Package	Role
fmt	Type-safe formatting (C++20/23 std::format sibling ecosystem)
spdlog	Structured, fast logging on top of fmt
Abseil	StrCat / StrFormat, flat hash maps, status-style utilities
range-v3	Lazy views and algorithms (bridge until full std ranges coverage)
Eigen	Dense linear algebra
nlohmann-json	Ergonomic JSON for config and non-hot paths
Catch2 / GTest	Unit and integration testing

Selection matrix

Requirement	Prefer	Avoid for that job
Timers, sockets, executors	Asio	Taskflow alone
HTTP / WebSocket framing	Beast	raw sockets without a protocol layer
Named multi-stage pipelines	Taskflow	ad-hoc thread pools without graph structure
Parallel for / reduce / sort	TBB (or HPX)	serial loops on large batches
Lazy composable async	stdexec	deeply nested callbacks without structure
Hot-path market JSON	simdjson	nlohmann-json on the critical path
Config / human-facing JSON	nlohmann-json	simdjson for one-off scripts (overkill)
Cross-process contracts	protobuf + gRPC	ad-hoc JSON RPC without schema
In-process service helpers	Folly (opt-in)	pulling Folly into every TU by default
HPC-style parallel runtime	HPX (opt-in)	using HPX as a network stack

Layered architecture

flowchart TB
  subgraph L1["L1 · Transport"]
    A[Asio]
    B[Beast]
    G[gRPC]
  end
  subgraph L2["L2 · Encoding"]
    S[simdjson]
    N[nlohmann-json]
    P[protobuf]
  end
  subgraph L3["L3 · Scheduling"]
    T[Taskflow]
    X[stdexec]
    BB[TBB]
    H[HPX]
  end
  subgraph L4["L4 · Compute & state"]
    E[Eigen]
    F[Folly F14 / containers]
    AB[Abseil]
  end
  L1 --> L2 --> L3 --> L4

Loading

Recommended study / adoption order

1. Asio           — event loop, posts, timers, strands
2. Beast          — HTTP messages, WebSocket streams
3. Taskflow       — explicit DAGs for multi-stage processing
4. TBB            — parallel_reduce / concurrent containers
5. stdexec        — sender/receiver composition (standard direction)
6. simdjson       — parse high-volume JSON off the I/O thread
7. protobuf/gRPC  — versioned contracts and service boundaries
8. Folly          — opt-in utilities once the base stack is solid
9. HPX            — opt-in when you need that runtime model

How this maps to tests

Suite	Command	Components exercised
Integration binary	./build/lib_smoke	Full base stack (+ Folly/HPX if enabled)
Asio + Beast	ctest -R beast	test_beast_asio
Taskflow	ctest -R taskflow	test_taskflow
Multi-lib Catch2	ctest -R libs / test_libs	fmt, TBB, simdjson, json, Eigen, Abseil, ranges, protobuf, stdexec
GTest install	ctest -R gtest	test_gtest_smoke
Folly profile	make folly	test_folly
HPX profile	make hpx	test_hpx

Build profiles

Profile	CMake flags	Use case
Base	defaults	Daily development, CI of core stack
Folly	-DLIB_SMOKE_WITH_FOLLY=ON	Service-utility integration
HPX	-DLIB_SMOKE_WITH_HPX=ON	Parallel runtime experiments
Full	Folly + HPX	Complete optional surface

See the repository README for install and Make targets.