Struct ResponseCachingMiddleware 

pub struct ResponseCachingMiddleware { /* private fields */ }

Response caching middleware for MCP servers.

Caches eligible responses with configurable TTL and bounded LRU eviction.

Production contexts are isolated by opaque session-state identity, state mutation revision, and complete verified authentication facts. An incomplete partition fails closed. tools/call is additionally disabled by default and requires an explicit per-tool allowlist entry via Self::include_tools.

Implementations

impl ResponseCachingMiddleware

pub fn new() -> Self

Creates response caching middleware with default bounds and TTLs.

tools/call caching remains off until Self::include_tools is used.

pub fn max_entries(self, max: usize) -> Self

Sets the maximum number of cache entries (0 disables storage).

pub fn max_size_bytes(self, max: usize) -> Self

Sets the maximum cache size in bytes (0 disables storage).

pub fn max_item_size(self, max: usize) -> Self

Sets the maximum size per cache item in bytes (0 disables storage).

pub fn list_ttl_secs(self, secs: u64) -> Self

Sets the TTL for list operations (tools/list, resources/list, prompts/list).

pub fn call_ttl_secs(self, secs: u64) -> Self

Sets the TTL for read/get operations and explicitly allowlisted calls.

pub fn disable_tools_list(self) -> Self

Disables caching for tools/list.

pub fn disable_resources_list(self) -> Self

Disables caching for resources/list.

pub fn disable_prompts_list(self) -> Self

Disables caching for prompts/list.

pub fn disable_tools_call(self) -> Self

Disables caching for tools/call.

pub fn disable_resources_read(self) -> Self

Disables caching for resources/read.

pub fn disable_prompts_get(self) -> Self

Disables caching for prompts/get.

pub fn include_tools(self, tools: Vec<String>) -> Self

Explicitly allowlists tools for tools/call caching.

An empty list disables tools/call caching. Exclusions configured with Self::exclude_tools take precedence over this allowlist.

pub fn exclude_tools(self, tools: Vec<String>) -> Self

Excludes tools from tools/call caching, overriding the allowlist.

pub fn stats(&self) -> CacheStats

Returns current cache statistics.

pub fn clear(&self)

Clears the entire cache.

pub fn invalidate_discovery(&self)

Invalidates every final discovery response and advances its cache generation. A response or lookup holding an older generation cannot reuse or repopulate the invalidated discovery state.

pub fn invalidate(&self, method: &str, params: Option<&Value>)

Invalidates every session/auth partition and every cursor page for a method and semantic-parameter set.

Trait Implementations

impl Debug for ResponseCachingMiddleware

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ResponseCachingMiddleware

fn default() -> Self

Returns the “default value” for a type.

impl Middleware for ResponseCachingMiddleware

fn on_request( &self, ctx: &McpContext, request: &JsonRpcRequest, ) -> McpResult<MiddlewareDecision>

Invoked before routing the request.

fn on_response( &self, ctx: &McpContext, request: &JsonRpcRequest, response: Value, ) -> McpResult<Value>

Invoked after a successful handler result is produced.

fn on_error( &self, _ctx: &McpContext, _request: &JsonRpcRequest, error: McpError, ) -> McpError

Invoked when a handler or middleware returns an error.