jsonrpc_core/
middleware.rs

1//! `IoHandler` middlewares
2
3use crate::calls::Metadata;
4use crate::types::{Call, Output, Request, Response};
5use futures_util::future::Either;
6use std::future::Future;
7use std::pin::Pin;
8
9/// RPC middleware
10pub trait Middleware<M: Metadata>: Send + Sync + 'static {
11	/// A returned request future.
12	type Future: Future<Output = Option<Response>> + Send + 'static;
13
14	/// A returned call future.
15	type CallFuture: Future<Output = Option<Output>> + Send + 'static;
16
17	/// Method invoked on each request.
18	/// Allows you to either respond directly (without executing RPC call)
19	/// or do any additional work before and/or after processing the request.
20	fn on_request<F, X>(&self, request: Request, meta: M, next: F) -> Either<Self::Future, X>
21	where
22		F: Fn(Request, M) -> X + Send + Sync,
23		X: Future<Output = Option<Response>> + Send + 'static,
24	{
25		Either::Right(next(request, meta))
26	}
27
28	/// Method invoked on each call inside a request.
29	///
30	/// Allows you to either handle the call directly (without executing RPC call).
31	fn on_call<F, X>(&self, call: Call, meta: M, next: F) -> Either<Self::CallFuture, X>
32	where
33		F: Fn(Call, M) -> X + Send + Sync,
34		X: Future<Output = Option<Output>> + Send + 'static,
35	{
36		Either::Right(next(call, meta))
37	}
38}
39
40/// Dummy future used as a noop result of middleware.
41pub type NoopFuture = Pin<Box<dyn Future<Output = Option<Response>> + Send>>;
42/// Dummy future used as a noop call result of middleware.
43pub type NoopCallFuture = Pin<Box<dyn Future<Output = Option<Output>> + Send>>;
44
45/// No-op middleware implementation
46#[derive(Clone, Debug, Default)]
47pub struct Noop;
48impl<M: Metadata> Middleware<M> for Noop {
49	type Future = NoopFuture;
50	type CallFuture = NoopCallFuture;
51}
52
53impl<M: Metadata, A: Middleware<M>, B: Middleware<M>> Middleware<M> for (A, B) {
54	type Future = Either<A::Future, B::Future>;
55	type CallFuture = Either<A::CallFuture, B::CallFuture>;
56
57	fn on_request<F, X>(&self, request: Request, meta: M, process: F) -> Either<Self::Future, X>
58	where
59		F: Fn(Request, M) -> X + Send + Sync,
60		X: Future<Output = Option<Response>> + Send + 'static,
61	{
62		repack(self.0.on_request(request, meta, |request, meta| {
63			self.1.on_request(request, meta, &process)
64		}))
65	}
66
67	fn on_call<F, X>(&self, call: Call, meta: M, process: F) -> Either<Self::CallFuture, X>
68	where
69		F: Fn(Call, M) -> X + Send + Sync,
70		X: Future<Output = Option<Output>> + Send + 'static,
71	{
72		repack(
73			self.0
74				.on_call(call, meta, |call, meta| self.1.on_call(call, meta, &process)),
75		)
76	}
77}
78
79impl<M: Metadata, A: Middleware<M>, B: Middleware<M>, C: Middleware<M>> Middleware<M> for (A, B, C) {
80	type Future = Either<A::Future, Either<B::Future, C::Future>>;
81	type CallFuture = Either<A::CallFuture, Either<B::CallFuture, C::CallFuture>>;
82
83	fn on_request<F, X>(&self, request: Request, meta: M, process: F) -> Either<Self::Future, X>
84	where
85		F: Fn(Request, M) -> X + Send + Sync,
86		X: Future<Output = Option<Response>> + Send + 'static,
87	{
88		repack(self.0.on_request(request, meta, |request, meta| {
89			repack(self.1.on_request(request, meta, |request, meta| {
90				self.2.on_request(request, meta, &process)
91			}))
92		}))
93	}
94
95	fn on_call<F, X>(&self, call: Call, meta: M, process: F) -> Either<Self::CallFuture, X>
96	where
97		F: Fn(Call, M) -> X + Send + Sync,
98		X: Future<Output = Option<Output>> + Send + 'static,
99	{
100		repack(self.0.on_call(call, meta, |call, meta| {
101			repack(
102				self.1
103					.on_call(call, meta, |call, meta| self.2.on_call(call, meta, &process)),
104			)
105		}))
106	}
107}
108
109impl<M: Metadata, A: Middleware<M>, B: Middleware<M>, C: Middleware<M>, D: Middleware<M>> Middleware<M>
110	for (A, B, C, D)
111{
112	type Future = Either<A::Future, Either<B::Future, Either<C::Future, D::Future>>>;
113	type CallFuture = Either<A::CallFuture, Either<B::CallFuture, Either<C::CallFuture, D::CallFuture>>>;
114
115	fn on_request<F, X>(&self, request: Request, meta: M, process: F) -> Either<Self::Future, X>
116	where
117		F: Fn(Request, M) -> X + Send + Sync,
118		X: Future<Output = Option<Response>> + Send + 'static,
119	{
120		repack(self.0.on_request(request, meta, |request, meta| {
121			repack(self.1.on_request(request, meta, |request, meta| {
122				repack(self.2.on_request(request, meta, |request, meta| {
123					self.3.on_request(request, meta, &process)
124				}))
125			}))
126		}))
127	}
128
129	fn on_call<F, X>(&self, call: Call, meta: M, process: F) -> Either<Self::CallFuture, X>
130	where
131		F: Fn(Call, M) -> X + Send + Sync,
132		X: Future<Output = Option<Output>> + Send + 'static,
133	{
134		repack(self.0.on_call(call, meta, |call, meta| {
135			repack(self.1.on_call(call, meta, |call, meta| {
136				repack(
137					self.2
138						.on_call(call, meta, |call, meta| self.3.on_call(call, meta, &process)),
139				)
140			}))
141		}))
142	}
143}
144
145#[inline(always)]
146fn repack<A, B, X>(result: Either<A, Either<B, X>>) -> Either<Either<A, B>, X> {
147	match result {
148		Either::Left(a) => Either::Left(Either::Left(a)),
149		Either::Right(Either::Left(b)) => Either::Left(Either::Right(b)),
150		Either::Right(Either::Right(x)) => Either::Right(x),
151	}
152}
jsonrpc_core/middleware.rs

jsonrpc_core/
middleware.rs
