compiler/rustc_query_system/src/cache.rs

   1 //! Cache for candidate selection.
   2
   3 use crate::dep_graph::{DepContext, DepNodeIndex};
   4
   5 use rustc_data_structures::fx::FxHashMap;
   6 use rustc_data_structures::sync::Lock;
   7
   8 use std::hash::Hash;
   9
  10 #[derive(Clone)]
  11 pub struct Cache<Key, Value> {
  12     hashmap: Lock<FxHashMap<Key, WithDepNode<Value>>>,
  13 }
  14
  15 impl<Key, Value> Default for Cache<Key, Value> {
  16     fn default() -> Self {
  17         Self { hashmap: Default::default() }
  18     }
  19 }
  20
  21 impl<Key, Value> Cache<Key, Value> {
  22     /// Actually frees the underlying memory in contrast to what stdlib containers do on `clear`
  23     pub fn clear(&self) {
  24         *self.hashmap.borrow_mut() = Default::default();
  25     }
  26 }
  27
  28 impl<Key: Eq + Hash, Value: Clone> Cache<Key, Value> {
  29     pub fn get<Tcx: DepContext>(&self, key: &Key, tcx: Tcx) -> Option<Value> {
  30         Some(self.hashmap.borrow().get(key)?.get(tcx))
  31     }
  32
  33     pub fn insert(&self, key: Key, dep_node: DepNodeIndex, value: Value) {
  34         self.hashmap.borrow_mut().insert(key, WithDepNode::new(dep_node, value));
  35     }
  36 }
  37
  38 #[derive(Clone, Eq, PartialEq)]
  39 pub struct WithDepNode<T> {
  40     dep_node: DepNodeIndex,
  41     cached_value: T,
  42 }
  43
  44 impl<T: Clone> WithDepNode<T> {
  45     pub fn new(dep_node: DepNodeIndex, cached_value: T) -> Self {
  46         WithDepNode { dep_node, cached_value }
  47     }
  48
  49     pub fn get<Tcx: DepContext>(&self, tcx: Tcx) -> T {
  50         tcx.dep_graph().read_index(self.dep_node);
  51         self.cached_value.clone()
  52     }
  53 }