Line data    Source code

       1              : use std::ops::{Deref, DerefMut};
       2              : use std::time::{Duration, Instant};
       3              : 
       4              : use moka::Expiry;
       5              : use moka::notification::RemovalCause;
       6              : 
       7              : use crate::control_plane::messages::ControlPlaneErrorMessage;
       8              : use crate::metrics::{
       9              :     CacheEviction, CacheKind, CacheOutcome, CacheOutcomeGroup, CacheRemovalCause, Metrics,
      10              : };
      11              : 
      12              : /// Default TTL used when caching errors from control plane.
      13              : pub const DEFAULT_ERROR_TTL: Duration = Duration::from_secs(30);
      14              : 
      15              : /// A generic trait which exposes types of cache's key and value,
      16              : /// as well as the notion of cache entry invalidation.
      17              : /// This is useful for [`Cached`].
      18              : pub(crate) trait Cache {
      19              :     /// Entry's key.
      20              :     type Key;
      21              : 
      22              :     /// Entry's value.
      23              :     type Value;
      24              : 
      25              :     /// Invalidate an entry using a lookup info.
      26              :     /// We don't have an empty default impl because it's error-prone.
      27              :     fn invalidate(&self, _: &Self::Key);
      28              : }
      29              : 
      30              : impl<C: Cache> Cache for &C {
      31              :     type Key = C::Key;
      32              :     type Value = C::Value;
      33              : 
      34            6 :     fn invalidate(&self, info: &Self::Key) {
      35            6 :         C::invalidate(self, info);
      36            6 :     }
      37              : }
      38              : 
      39              : /// Wrapper for convenient entry invalidation.
      40              : pub(crate) struct Cached<C: Cache, V = <C as Cache>::Value> {
      41              :     /// Cache + lookup info.
      42              :     pub(crate) token: Option<(C, C::Key)>,
      43              : 
      44              :     /// The value itself.
      45              :     pub(crate) value: V,
      46              : }
      47              : 
      48              : impl<C: Cache, V> Cached<C, V> {
      49              :     /// Place any entry into this wrapper; invalidation will be a no-op.
      50            1 :     pub(crate) fn new_uncached(value: V) -> Self {
      51            1 :         Self { token: None, value }
      52            1 :     }
      53              : 
      54              :     /// Drop this entry from a cache if it's still there.
      55            6 :     pub(crate) fn invalidate(self) -> V {
      56            6 :         if let Some((cache, info)) = &self.token {
      57            6 :             cache.invalidate(info);
      58            6 :         }
      59            6 :         self.value
      60            6 :     }
      61              : 
      62              :     /// Tell if this entry is actually cached.
      63           16 :     pub(crate) fn cached(&self) -> bool {
      64           16 :         self.token.is_some()
      65           16 :     }
      66              : }
      67              : 
      68              : impl<C: Cache, V> Deref for Cached<C, V> {
      69              :     type Target = V;
      70              : 
      71            0 :     fn deref(&self) -> &Self::Target {
      72            0 :         &self.value
      73            0 :     }
      74              : }
      75              : 
      76              : impl<C: Cache, V> DerefMut for Cached<C, V> {
      77            0 :     fn deref_mut(&mut self) -> &mut Self::Target {
      78            0 :         &mut self.value
      79            0 :     }
      80              : }
      81              : 
      82              : pub type ControlPlaneResult<T> = Result<T, Box<ControlPlaneErrorMessage>>;
      83              : 
      84              : #[derive(Clone, Copy)]
      85              : pub struct CplaneExpiry {
      86              :     pub error: Duration,
      87              : }
      88              : 
      89              : impl Default for CplaneExpiry {
      90           15 :     fn default() -> Self {
      91           15 :         Self {
      92           15 :             error: DEFAULT_ERROR_TTL,
      93           15 :         }
      94           15 :     }
      95              : }
      96              : 
      97              : impl CplaneExpiry {
      98           29 :     pub fn expire_early<V>(
      99           29 :         &self,
     100           29 :         value: &ControlPlaneResult<V>,
     101           29 :         updated: Instant,
     102           29 :     ) -> Option<Duration> {
     103           29 :         match value {
     104           25 :             Ok(_) => None,
     105            4 :             Err(err) => Some(self.expire_err_early(err, updated)),
     106              :         }
     107           29 :     }
     108              : 
     109            4 :     pub fn expire_err_early(&self, err: &ControlPlaneErrorMessage, updated: Instant) -> Duration {
     110            4 :         err.status
     111            4 :             .as_ref()
     112            4 :             .and_then(|s| s.details.retry_info.as_ref())
     113            4 :             .map_or(self.error, |r| r.retry_at.into_std() - updated)
     114            4 :     }
     115              : }
     116              : 
     117              : impl<K, V> Expiry<K, ControlPlaneResult<V>> for CplaneExpiry {
     118           24 :     fn expire_after_create(
     119           24 :         &self,
     120           24 :         _key: &K,
     121           24 :         value: &ControlPlaneResult<V>,
     122           24 :         created_at: Instant,
     123           24 :     ) -> Option<Duration> {
     124           24 :         self.expire_early(value, created_at)
     125           24 :     }
     126              : 
     127            5 :     fn expire_after_update(
     128            5 :         &self,
     129            5 :         _key: &K,
     130            5 :         value: &ControlPlaneResult<V>,
     131            5 :         updated_at: Instant,
     132            5 :         _duration_until_expiry: Option<Duration>,
     133            5 :     ) -> Option<Duration> {
     134            5 :         self.expire_early(value, updated_at)
     135            5 :     }
     136              : }
     137              : 
     138           15 : pub fn eviction_listener(kind: CacheKind, cause: RemovalCause) {
     139           15 :     let cause = match cause {
     140            3 :         RemovalCause::Expired => CacheRemovalCause::Expired,
     141            6 :         RemovalCause::Explicit => CacheRemovalCause::Explicit,
     142            5 :         RemovalCause::Replaced => CacheRemovalCause::Replaced,
     143            1 :         RemovalCause::Size => CacheRemovalCause::Size,
     144              :     };
     145           15 :     Metrics::get()
     146           15 :         .cache
     147           15 :         .evicted_total
     148           15 :         .inc(CacheEviction { cache: kind, cause });
     149           15 : }
     150              : 
     151              : #[inline]
     152           11 : pub fn count_cache_outcome<T>(kind: CacheKind, cache_result: Option<T>) -> Option<T> {
     153           11 :     let outcome = if cache_result.is_some() {
     154           10 :         CacheOutcome::Hit
     155              :     } else {
     156            1 :         CacheOutcome::Miss
     157              :     };
     158           11 :     Metrics::get().cache.request_total.inc(CacheOutcomeGroup {
     159           11 :         cache: kind,
     160           11 :         outcome,
     161           11 :     });
     162           11 :     cache_result
     163           11 : }
     164              : 
     165              : #[inline]
     166           29 : pub fn count_cache_insert(kind: CacheKind) {
     167           29 :     Metrics::get().cache.inserted_total.inc(kind);
     168           29 : }