luaj/test/junit/org/luaj/vm2/WeakTableTest.java

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package org.luaj.vm2;

import java.lang.ref.WeakReference;

abstract public class WeakTableTest extends TableTest {
	
	public static class MyData {
		public final int value;
		public MyData( int value ) {
			this.value = value;
		}
		public int hashCode() {
			return value;
		}
		public boolean equals( Object o ) {
			return (o instanceof MyData) && ((MyData)o).value == value;
		}
		public String toString() {
			return "mydata-"+value;
		}
	}

	static void collectGarbage() {
		Runtime rt = Runtime.getRuntime();
		rt.gc();
		try {
			Thread.sleep(20);
			rt.gc();
			Thread.sleep(20);
		} catch ( Exception e ) {
			e.printStackTrace();
		}
		rt.gc();
	}
	
	public static class WeakValueTableTest extends WeakTableTest {
		protected LuaTable new_Table() { return new WeakTable(false, true);	}
		protected LuaTable new_Table(int n,int m) { return new WeakTable(false, true); }

		public void testWeakValuesTable() {
			LuaTable t = new_Table();
			
			Object obj = new Object();
			LuaTable tableValue = new LuaTable();
			LuaString stringValue = LuaString.valueOf("this is a test");
			
			t.set("table", tableValue);
			t.set("userdata", LuaValue.userdataOf(obj, null));
			t.set("string", stringValue);
			t.set("string2", LuaString.valueOf("another string"));
			assertTrue("table must have at least 4 elements", t.getHashLength() > 4);

			// check that table can be used to get elements 
			assertEquals(tableValue, t.get("table"));
			assertEquals(stringValue, t.get("string"));
			assertEquals(obj, t.get("userdata").checkuserdata());

			// nothing should be collected, since we have strong references here
			collectGarbage();
			
			// check that elements are still there 
			assertEquals(tableValue, t.get("table"));
			assertEquals(stringValue, t.get("string"));
			assertEquals(obj, t.get("userdata").checkuserdata());

			// drop our strong references
			obj = null;
			tableValue = null;
			stringValue = null;
			
			// Garbage collection should cause weak entries to be dropped.
			collectGarbage();
			
			// check that they are dropped
			assertEquals(LuaValue.NIL, t.get("table"));
			assertEquals(LuaValue.NIL, t.get("userdata"));
			assertFalse("strings should not be in weak references", t.get("string").isnil());
		}
	}
	
	public static class WeakKeyTableTest extends WeakTableTest {
		protected LuaTable new_Table() { return new WeakTable(true, false);	}
		protected LuaTable new_Table(int n,int m) { return new WeakTable(true, false); }
		
		public void testWeakKeysTable() {
			LuaTable t = new WeakTable(true, false);
			
			LuaValue key = LuaValue.userdataOf(new MyData(111));
			LuaValue val = LuaValue.userdataOf(new MyData(222));
			
			// set up the table
			t.set( key, val );
			assertEquals( val, t.get(key) );
			System.gc();
			assertEquals( val, t.get(key) );

			// drop key and value references, replace them with new ones
			WeakReference origkey = new WeakReference(key);
			WeakReference origval = new WeakReference(val);
			key = LuaValue.userdataOf(new MyData(111));
			val = LuaValue.userdataOf(new MyData(222));

			// new key and value should be interchangeable (feature of this test class)
			assertEquals( key, origkey.get() );
			assertEquals( val, origval.get() );
			assertEquals( val, t.get(key) );
			assertEquals( val, t.get((LuaValue) origkey.get()) );
			assertEquals( origval.get(), t.get(key) );

			// value should not be reachable after gc
			collectGarbage();
			assertEquals( null, origkey.get() );
			assertEquals( LuaValue.NIL, t.get(key) );
			collectGarbage();
			assertEquals( null, origval.get() );
		}
	}
	
	public static class WeakKeyValueTableTest extends WeakTableTest {
		protected LuaTable new_Table() { return new WeakTable(true, true);	}
		protected LuaTable new_Table(int n,int m) { return new WeakTable(true, true); }
		
		public void testWeakKeysValuesTable() {
			LuaTable t = new WeakTable(true, true);
			
			LuaValue key = LuaValue.userdataOf(new MyData(111));
			LuaValue val = LuaValue.userdataOf(new MyData(222));
			LuaValue key2 = LuaValue.userdataOf(new MyData(333));
			LuaValue val2 = LuaValue.userdataOf(new MyData(444));
			LuaValue key3 = LuaValue.userdataOf(new MyData(555));
			LuaValue val3 = LuaValue.userdataOf(new MyData(666));
			
			// set up the table
			t.set( key, val );
			t.set( key2, val2 );
			t.set( key3, val3 );
			assertEquals( val, t.get(key) );
			assertEquals( val2, t.get(key2) );
			assertEquals( val3, t.get(key3) );
			System.gc();
			assertEquals( val, t.get(key) );
			assertEquals( val2, t.get(key2) );
			assertEquals( val3, t.get(key3) );

			// drop key and value references, replace them with new ones
			WeakReference origkey = new WeakReference(key);
			WeakReference origval = new WeakReference(val);
			WeakReference origkey2 = new WeakReference(key2);
			WeakReference origval2 = new WeakReference(val2);
			WeakReference origkey3 = new WeakReference(key3);
			WeakReference origval3 = new WeakReference(val3);
			key = LuaValue.userdataOf(new MyData(111));
			val = LuaValue.userdataOf(new MyData(222));
			key2 = LuaValue.userdataOf(new MyData(333));
			// don't drop val2, or key3
			val3 = LuaValue.userdataOf(new MyData(666));

			// no values should be reachable after gc
			collectGarbage();
			assertEquals( null, origkey.get() );
			assertEquals( null, origval.get() );
			assertEquals( null, origkey2.get() );
			assertEquals( null, origval3.get() );
			assertEquals( LuaValue.NIL, t.get(key) );
			assertEquals( LuaValue.NIL, t.get(key2) );
			assertEquals( LuaValue.NIL, t.get(key3) );

			// all originals should be gone after gc, then access
			val2 = null;
			key3 = null;
			collectGarbage();
			assertEquals( null, origval2.get() );
			assertEquals( null, origkey3.get() );
		}
	}	
}