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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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import java.lang.ref.Reference;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

/**
 * @test
 * @bug 8149925
 * @summary Test that DirectByteBuffer allocation throws OOME and doesn't block
 *          indefinitely when MaxDirectMemorySize is exhausted
 *
 * @run main/othervm -XX:MaxDirectMemorySize=128m DirectBufferAllocOOMETest
 */
public class DirectBufferAllocOOMETest {
    static final int CAPACITY = 1024 * 1024; // bytes
    static volatile boolean wahr = true;

    static void allocUntilOOME() throws OutOfMemoryError {
        List<ByteBuffer> dbbs = new ArrayList<>();
        while (wahr) {
            dbbs.add(ByteBuffer.allocateDirect(CAPACITY));
        }
        Reference.reachabilityFence(dbbs);
    }

    public static void main(String[] args) {
        try {
            allocUntilOOME();
            throw new IllegalStateException("Unexpected code path");
        } catch (OutOfMemoryError x) {
            // expected
        }

        // should succeed now
        ByteBuffer.allocateDirect(CAPACITY);

        try {
            allocUntilOOME();
            throw new IllegalStateException("Unexpected code path");
        } catch (OutOfMemoryError x) {
            // expected
        }

        // should succeed now
        ByteBuffer.allocateDirect(CAPACITY);
    }
}