From 6f27e52c6bf07061e6229e45cdd711bf70f1546a Mon Sep 17 00:00:00 2001
From: Harrison <yunyangdeng@gmail.com>
Date: Wed, 29 Apr 2020 16:23:39 -0500
Subject: [PATCH] Improved locking scheme of cache.

---
 .../islandsurvivalcraft/caching/Cache.java    | 26 +++++++------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/src/main/java/ca/recrown/islandsurvivalcraft/caching/Cache.java b/src/main/java/ca/recrown/islandsurvivalcraft/caching/Cache.java
index cb48cf6..4f9dd4a 100644
--- a/src/main/java/ca/recrown/islandsurvivalcraft/caching/Cache.java
+++ b/src/main/java/ca/recrown/islandsurvivalcraft/caching/Cache.java
@@ -1,17 +1,15 @@
 package ca.recrown.islandsurvivalcraft.caching;
 
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
 
 public class Cache<K, V> {
     private final int maxSize;
     private final ConcurrentHashMap<K, CacheValue<K, V>> data;
     private final UsageStack<K, V> usage = new UsageStack<>();
-    private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
-    private final WriteLock writeLock = lock.writeLock();
-    private final ReadLock readLock = lock.readLock();
+    private final ReentrantLock lock = new ReentrantLock();
 
     public Cache(int maxSize) {
         data = new ConcurrentHashMap<>(maxSize + 1, 0.75f, 6);
@@ -33,7 +31,7 @@ public class Cache<K, V> {
         if (data.containsKey(key)) {
             data.get(key).value = value;
         } else {
-            writeLock.lock();
+            lock.lock();
             try {
                 CacheValue<K, V> val = new CacheValue<>();
                 val.key = key;
@@ -44,7 +42,7 @@ public class Cache<K, V> {
                     data.remove(usage.pop().key);
                 }
             } finally {
-                writeLock.unlock();
+                lock.unlock();
             }
         }
     }
@@ -57,15 +55,9 @@ public class Cache<K, V> {
      * @return the value associated to the key.
      */
     public V get(K key) {
-        readLock.lock();
-        CacheValue<K, V> value = null;
-        try {
-            if (!data.containsKey(key)) return null;
-            value = data.get(key);
-            usage.tryMoveToTop(value);
-        } finally {
-            readLock.unlock();
-        }
+        CacheValue<K, V> value = data.get(key);
+        usage.tryMoveToTop(value);
+        if (value == null) return null;
         return value.value;
     }
 
@@ -73,12 +65,12 @@ public class Cache<K, V> {
      * Clears the cache of all values.
      */
     public void clearCache() {
-        writeLock.lock();
+        lock.lock();
         try {
             data.clear();
             usage.clear();
         } finally {
-            writeLock.unlock();
+            lock.unlock();
         }
     }
 }
\ No newline at end of file