Reworked cache, this time with less hashmap accesses.

src/main/java/ca/recrown/islandsurvivalcraft/caching/Cache.java

@@ -1,59 +1,38 @@
 package ca.recrown.islandsurvivalcraft.caching;
 
-import java.util.HashMap;
-import java.util.LinkedList;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
 
 public class Cache<Key, Value> {
     private final int maxSize;
-    private final HashMap<Key, Value> data;
-    private final HashMap<Key, Integer> occurrences;
-    private final LinkedList<Key> occurrenceOrder;
+    private final ConcurrentHashMap<Key, CacheValue<Value>> data;
+    private final ConcurrentLinkedQueue<Key> occurrenceOrder;
 
     public Cache(int maxSize) {
-        data = new HashMap<>(maxSize);
-        occurrenceOrder = new LinkedList<>();
+        data = new ConcurrentHashMap<>(maxSize);
+        occurrenceOrder = new ConcurrentLinkedQueue<>();
         this.maxSize = maxSize;
-        this.occurrences = new HashMap<>();
     }
 
     public Cache() {
         this(1024);
     }
 
-    public synchronized void setValue(Key key, Value value) {
-        if (!data.containsKey(key)) {
-            if (data.size() >= maxSize) {
-                while (occurrences.get(occurrenceOrder.peek()) > 1) {
-                    occurencesTrackedPoll();
-                }
-                data.remove(occurencesTrackedPoll());
-            }
-            occurrencesTrackedAdd(key);
-        }
-        data.put(key, value);
-    }
-
-
-    private void occurrencesTrackedAdd(Key key) {
-        int occ = 0;
-        if (occurrences.get(key) != null) {
-            occ = occurrences.get(key);
-        }
-        occ++;
-        occurrences.put(key, occ);
+    public void setValue(Key key, Value value) {
+        data.put(key, new CacheValue<>(value));
         occurrenceOrder.add(key);
-    }
-
-    private Key occurencesTrackedPoll() {
-        Key key = occurrenceOrder.poll();
-        int occ = 0;
-        if (occurrences.get(key) != null) {
-            occ = occurrences.get(key);
+        if (data.size() > maxSize) {
+            int occ = 0;
+            do {
+                Key potentialKey = occurrenceOrder.poll();
+                CacheValue<Value> potential = data.get(potentialKey);
+                potential.decreaseOccurence();
+                occ = potential.getOccurrence();
+                if (occ < 1) {
+                    data.remove(potentialKey);
+                } 
+            } while (occ > 0);
         }
-        occ--;
-        if (occ < 0) throw new IllegalStateException();
-        occurrences.put(key, occ);
-        return key;
     }
 
     /**
@@ -63,14 +42,17 @@ public class Cache<Key, Value> {
      * @param key the key associated with the value.
      * @return the value associated to the key.
      */
-    public synchronized Value getValue(Key key) {
-        occurrencesTrackedAdd(key);
-        return data.get(key);
+    public Value getValue(Key key) {
+        CacheValue<Value> res = data.get(key);
+        if (res == null) return null;
+
+        res.increaseOccurrence();
+        occurrenceOrder.add(key);
+        return res.getValue();
     }
 
-    public synchronized void clearCache() {
+    public void clearCache() {
         data.clear();
         occurrenceOrder.clear();
-        occurrences.clear();
     }
 }

src/main/java/ca/recrown/islandsurvivalcraft/caching/CacheValue.java

@@ -0,0 +1,32 @@
+package ca.recrown.islandsurvivalcraft.caching;
+
+public class CacheValue <ValueType> {
+    private int occurrence = 1;
+    private final ValueType value;
+
+    /**
+     * @return the occurrence
+     */
+    public int getOccurrence() {
+        return occurrence;
+    }
+
+    public void increaseOccurrence() {
+        occurrence++;
+    }
+
+    public void decreaseOccurence() {
+        occurrence--;
+    }
+
+    public CacheValue(ValueType value) {
+        this.value = value;
+    }
+
+    /**
+     * @return the value
+     */
+    public ValueType getValue() {
+        return value;
+    }
+}

src/test/java/ca/recrown/islandsurvivalcraft/caching/CacheTest.java

@@ -66,10 +66,10 @@ public class CacheTest {
 
         Cache<Integer, Integer> largeCache = new Cache<>(amount/2);
 
-        int[] expected = new int[amount];
+        int[] values = new int[amount];
         for (int i = 0; i < amount; i++) {
-            expected[i] = random.nextInt();
-            largeCache.setValue(i, expected[i]);
+            values[i] = random.nextInt();
+            largeCache.setValue(i, values[i]);
         }
 
         for (int i = 0; i < amount /2; i++) {
@@ -77,7 +77,7 @@ public class CacheTest {
         }
 
         for (int i = amount /2; i < amount; i++) {
-            assertEquals(expected[i], largeCache.getValue(i), "Current accessor: " + i);
+            assertEquals(values[i], largeCache.getValue(i), "Current accessor: " + i);
         }
     }
 
@@ -88,10 +88,10 @@ public class CacheTest {
 
         Cache<Integer, Integer> largeCache = new Cache<>(amount/2);
 
-        int[] expected = new int[amount];
+        int[] values = new int[amount];
         for (int i = 0; i < amount; i++) {
-            expected[i] = random.nextInt();
-            largeCache.setValue(i, expected[i]);
+            values[i] = random.nextInt();
+            largeCache.setValue(i, values[i]);
             largeCache.getValue(0);
         }
 
@@ -100,9 +100,9 @@ public class CacheTest {
         }
 
         for (int i = (amount /2) + 1; i < amount; i++) {
-            assertEquals(expected[i], largeCache.getValue(i), "Current accessor: " + i);
+            assertEquals(values[i], largeCache.getValue(i), "Current accessor: " + i);
         }
 
-        assertEquals(expected[0], largeCache.getValue(0));
+        assertEquals(values[0], largeCache.getValue(0));
     }
 }