Greatly improved memory consumption in cache, stale data no longer pile up

reCTBN/src/parameter_learning.rs

@@ -1,6 +1,7 @@
 //! Module containing methods used to learn the parameters.
 
 use std::collections::{BTreeSet, HashMap};
+use std::mem;
 
 use ndarray::prelude::*;
 
@@ -168,14 +169,18 @@ impl ParameterLearning for BayesianApproach {
 // TODO: Move to constraint_based_algorithm.rs
 pub struct Cache<'a, P: ParameterLearning> {
     parameter_learning: &'a P,
-    cache_persistent: HashMap<Option<BTreeSet<usize>>, Params>,
+    cache_persistent_small: HashMap<Option<BTreeSet<usize>>, Params>,
+    cache_persistent_big: HashMap<Option<BTreeSet<usize>>, Params>,
+    parent_set_size_small: usize,
 }
 
 impl<'a, P: ParameterLearning> Cache<'a, P> {
     pub fn new(parameter_learning: &'a P) -> Cache<'a, P> {
         Cache {
             parameter_learning,
-            cache_persistent: HashMap::new(),
+            cache_persistent_small: HashMap::new(),
+            cache_persistent_big: HashMap::new(),
+            parent_set_size_small: 0,
         }
     }
     pub fn fit<T: process::NetworkProcess>(
@@ -185,17 +190,44 @@ impl<'a, P: ParameterLearning> Cache<'a, P> {
         node: usize,
         parent_set: Option<BTreeSet<usize>>,
     ) -> Params {
-        match self.cache_persistent.get(&parent_set) {
-            // TODO: Bettern not clone `params`, useless clock cycles, RAM use and I/O
+        let parent_set_len = parent_set.as_ref().unwrap().len();
+        if parent_set_len > self.parent_set_size_small + 1 {
+            //self.cache_persistent_small = self.cache_persistent_big;
+            mem::swap(
+                &mut self.cache_persistent_small,
+                &mut self.cache_persistent_big,
+            );
+            self.cache_persistent_big = HashMap::new();
+            self.parent_set_size_small += 1;
+        }
+
+        if parent_set_len > self.parent_set_size_small {
+            match self.cache_persistent_big.get(&parent_set) {
+                // TODO: Better not clone `params`, useless clock cycles, RAM use and I/O
+                // not cloning requires a minor and reasoned refactoring across the library
+                Some(params) => params.clone(),
+                None => {
+                    let params =
+                        self.parameter_learning
+                            .fit(net, dataset, node, parent_set.clone());
+                    self.cache_persistent_big.insert(parent_set, params.clone());
+                    params
+                }
+            }
+        } else {
+            match self.cache_persistent_small.get(&parent_set) {
+                // TODO: Better not clone `params`, useless clock cycles, RAM use and I/O
                 // not cloning requires a minor and reasoned refactoring across the library
                 Some(params) => params.clone(),
                 None => {
-                let params = self
-                    .parameter_learning
+                    let params =
+                        self.parameter_learning
                             .fit(net, dataset, node, parent_set.clone());
-                self.cache_persistent.insert(parent_set, params.clone());
+                    self.cache_persistent_small
+                        .insert(parent_set, params.clone());
                     params
                 }
             }
         }
+    }
 }