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Architecture & Threading Model

cpp-http inherits its multi-threaded, asynchronous architecture from cpp-tcpnet. This ensures that network IO, request parsing, and route callback processing do not block your main application logic.

graph TD classDef client fill:#fdf4ff,stroke:#d946ef,stroke-width:2px; classDef listener fill:#eff6ff,stroke:#3b82f6,stroke-width:2px; classDef worker fill:#ecfdf5,stroke:#10b981,stroke-width:2px; classDef handler fill:#fff1f2,stroke:#f43f5e,stroke-width:2px; Client[Client Browser/API]:::client -->|1. HTTP Request| TcpListener[TcpListener Poll Thread]:::listener TcpListener -->|2. TCP Bytes| WorkerPool[Worker Pool Thread]:::worker subgraph WorkerPoolThread [Worker Pool Task] WorkerPool -->|3. HandleIncomingData| Reassembly[Rebuild & Buffer Fragments]:::worker Reassembly -->|4. Parse Request| Router[HTTP Route Dispatcher]:::worker Router -->|5. Execute Callback| Handler[User Callback Lambda]:::handler end Handler -->|6. HttpResponse| TcpListener TcpListener -->|7. TCP Send| Client

The Three Threading Pillars

The Poller Thread: The underlying TcpListener spawns a background thread that monitors client sockets using non-blocking OS selectors (poll or WSAPoll). This thread is responsible for receiving TCP byte blocks and sending outgoing responses.
The Worker Pool: Whenever new TCP bytes are read, they are pushed as work items onto a cppasyncworker::WorkerPool thread pool. The HandleIncomingData protocol engine runs concurrently on these worker threads, parsing the HTTP headers and executing your route handler callbacks.
The Event Cleanup Thread: To clean up session buffers when connections drop, HttpServer subscribes to client disconnect events via cpppubsub::PubSub. It runs a dedicated, detached background thread that checks for disconnected session events and safely deletes inactive buffers from the sessions_ map.

Sibling Libraries

cpp-http acts as a protocol layer on top of a highly optimized stack:

cpp-tcpnet: The foundational socket management, polling loops, and TLS engine.
cpp-pubsub: The event broker that coordinates state cleanups.
cpp-asyncworker: The worker thread pool scheduling network tasks.

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