Synchronize cache (#63)

common/src/main/java/com/lishid/openinv/util/Cache.java

@@ -9,7 +9,7 @@ import com.google.common.collect.Multimap;
 import com.google.common.collect.TreeMultimap;
 
 /**
- * A minimal time-based cache implementation backed by a HashMap and TreeMultimap.
+ * A minimal thread-safe time-based cache implementation backed by a HashMap and TreeMultimap.
  * 
  * @author Jikoo
  */
@@ -59,9 +59,11 @@ public class Cache<K, V> {
         // Invalidate key - runs lazy check and ensures value won't be cleaned up early
         invalidate(key);
 
+        synchronized (internal) {
             internal.put(key, value);
             expiry.put(System.currentTimeMillis() + retention, key);
         }
+    }
 
     /**
      * Returns the value to which the specified key is mapped, or null if no value is mapped for the key.
@@ -70,11 +72,13 @@ public class Cache<K, V> {
      * @return the value to which the specified key is mapped, or null if no value is mapped for the key
      */
     public V get(K key) {
+        synchronized (internal) {
             // Run lazy check to clean cache
             lazyCheck();
 
             return internal.get(key);
         }
+    }
 
     /**
      * Returns true if the specified key is mapped to a value.
@@ -83,11 +87,13 @@ public class Cache<K, V> {
      * @return true if a mapping exists for the specified key
      */
     public boolean containsKey(K key) {
+        synchronized (internal) {
             // Run lazy check to clean cache
             lazyCheck();
 
             return internal.containsKey(key);
         }
+    }
 
     /**
      * Forcibly invalidates a key, even if it is considered to be in use.
@@ -95,6 +101,7 @@ public class Cache<K, V> {
      * @param key key to invalidate
      */
     public void invalidate(K key) {
+        synchronized (internal) {
             // Run lazy check to clean cache
             lazyCheck();
 
@@ -114,17 +121,20 @@ public class Cache<K, V> {
                 }
             }
         }
+    }
 
     /**
      * Forcibly invalidates all keys, even if they are considered to be in use.
      */
     public void invalidateAll() {
+        synchronized (internal) {
             for (V value : internal.values()) {
                 postRemoval.run(value);
             }
             expiry.clear();
             internal.clear();
         }
+    }
 
     /**
      * Invalidate all expired keys that are not considered in use. If a key is expired but is