Data: Clear more caches when under memory pressure and at shutdown

core/java/src/net/i2p/data/Hash.java

@@ -104,4 +104,11 @@ public class Hash extends SimpleDataStructure {
         }
         return _base64ed;
     }
+
+    /**
+     *  @since 0.9.17
+     */
+    public static void clearCache() {
+        _cache.clear();
+    }
 }

core/java/src/net/i2p/data/PublicKey.java

@@ -68,4 +68,11 @@ public class PublicKey extends SimpleDataStructure {
     public int length() {
         return KEYSIZE_BYTES;
     }
+
+    /**
+     *  @since 0.9.17
+     */
+    public static void clearCache() {
+        _cache.clear();
+    }
 }

core/java/src/net/i2p/data/SDSCache.java

@@ -91,9 +91,16 @@ public class SDSCache<V extends SimpleDataStructure> {
      */
     private class Shutdown implements Runnable {
         public void run() {
-            synchronized(_cache) {
-                _cache.clear();
-            }
+            clear();
+        }
+    }
+
+    /**
+     * @since 0.9.17
+     */
+    public void clear() {
+        synchronized(_cache) {
+            _cache.clear();
         }
     }
 

core/java/src/net/i2p/data/SigningPublicKey.java

@@ -193,4 +193,11 @@ public class SigningPublicKey extends SimpleDataStructure {
         buf.append(']');
         return buf.toString();
     }
+
+    /**
+     *  @since 0.9.17
+     */
+    public static void clearCache() {
+        _cache.clear();
+    }
 }