Struct ClientCacheConfig 

#[non_exhaustive]
pub struct ClientCacheConfig {
    pub enabled: bool,
    pub default_ttl: Duration,
    pub max_ttl: Duration,
    pub private_partition: Option<String>,
    pub max_entries: usize,
    pub serve_stale_on_error: bool,
}

Available on crate feature mcp and crate feature tools and (crate features client or server) only.

Configuration for the built-in MCP client response cache.

A cache is allocated per client Peer. Public responses may be reused throughout that client connection. Private responses are additionally partitioned by private_partition; changing the partition drops every private entry while preserving public entries.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

enabled: bool

Enables cache reads and writes.

default_ttl: Duration

TTL used when a backwards-compatible server omits ttlMs.

The default is zero, which leaves such responses immediately stale.

max_ttl: Duration

Upper bound applied to both server-provided and default TTLs.

private_partition: Option<String>

Stable opaque identity for the current authorization context.

A single-principal client may leave this unset because each client owns its own in-memory store. Gateways or clients that change principals on an existing connection should set this value and update it whenever the authorization context changes.

max_entries: usize

Maximum number of responses retained by the in-memory cache.

A value of zero disables the size limit.

serve_stale_on_error: bool

Serves an expired cached response when a re-fetch fails.

SEP-2549 permits clients to serve stale responses if errors occur while re-fetching (for example, network issues or server downtime). When this is enabled the client retains expired entries so it can fall back to the last known response instead of surfacing the transport or server error. A successful re-fetch always overwrites the stale entry.

Implementations

impl ClientCacheConfig

pub fn disabled() -> ClientCacheConfig

Returns a configuration that disables all cache reads and writes.

pub fn with_default_ttl(self, default_ttl: Duration) -> ClientCacheConfig

Sets the TTL used when a response omits ttlMs.

pub fn with_max_ttl(self, max_ttl: Duration) -> ClientCacheConfig

Sets the maximum TTL the client will honour.

pub fn with_private_partition( self, partition: impl Into<String>, ) -> ClientCacheConfig

Sets the stable partition for private responses.

pub fn with_max_entries(self, max_entries: usize) -> ClientCacheConfig

Sets the maximum number of retained responses.

pub fn with_serve_stale_on_error( self, serve_stale_on_error: bool, ) -> ClientCacheConfig

Controls whether an expired response may be served when a re-fetch fails.

Trait Implementations

impl Clone for ClientCacheConfig

fn clone(&self) -> ClientCacheConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ClientCacheConfig

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

Formats the value using the given formatter.

impl Default for ClientCacheConfig

fn default() -> ClientCacheConfig

Returns the “default value” for a type.

impl Eq for ClientCacheConfig

impl PartialEq for ClientCacheConfig

fn eq(&self, other: &ClientCacheConfig) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ClientCacheConfig