Struct JsonSocketBuilder 

pub struct JsonSocketBuilder<T> { /* private fields */ }

Route builder that expects and deserialises a JSON request body of type T.

Obtained from ServerMechanism::json. Optionally attach shared state via state, or finalise immediately with onconnect / onconnect_sync.

Implementations

impl<T: DeserializeOwned + Send + 'static> JsonSocketBuilder<T>

pub fn onconnect<F, Fut, Re>(self, handler: F) -> SocketType

where F: Fn(T) -> Fut + Clone + Send + Sync + 'static, Fut: Future<Output = Result<Re, Rejection>> + Send, Re: Reply + Send,

Finalises this route with an async handler that receives the deserialised JSON body.

Before the handler is called, the incoming request body is parsed as Content-Type: application/json and deserialised into T. The handler receives a ready-to-use T — no manual parsing is needed. If the body is absent or cannot be decoded the request is rejected before the handler is ever invoked.

The handler must return Result<impl Reply, Rejection>. Returns a SocketType ready to be passed to Server::mechanism.

pub unsafe fn onconnect_sync<F, Re>(self, handler: F) -> SocketType

where F: Fn(T) -> Result<Re, Rejection> + Clone + Send + Sync + 'static, Re: Reply + Send + 'static,

Finalises this route with a synchronous handler that receives the deserialised JSON body.

The body is decoded into T before the handler is dispatched, identical to the async variant. The closure may block but must complete quickly to avoid exhausting the blocking thread pool.

Returns a SocketType ready to be passed to Server::mechanism.

Safety

Every incoming request spawns an independent task on Tokio’s blocking thread pool. The pool caps the number of live OS threads (default 512), but the queue of waiting tasks is unbounded — under a traffic surge, tasks accumulate without limit, consuming unbounded memory and causing severe latency spikes or OOM crashes before any queued task gets a chance to run. Additionally, any panic inside the handler is silently converted into a Rejection, masking runtime errors. Callers must ensure the handler completes quickly and that adequate backpressure or rate limiting is applied externally.

pub fn state<S: Clone + Send + Sync + 'static>( self, state: S, ) -> StatefulJsonSocketBuilder<T, S>

Attaches shared state S, transitioning to StatefulJsonSocketBuilder.

Alternative ordering to .state(s).json::<T>() — both produce the same route. A fresh clone of S is injected alongside the JSON-decoded T on every request. The handler will receive (state: S, body: T).

S must be Clone + Send + Sync + 'static.