Stop creating unnecessary exceptions with MultiException #2580
This doesn't actually stop creating the unnecessary exception instead it stop running the expensive `fillInStackTrace()` unless we actually need it. This does result in the stack trace being set to where we throw the exception rather than when we create it. Signed-off-by: Luke Butters <lbutters@funnelback.com>
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@ -31,11 +31,28 @@ import java.util.List;
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public class MultiException extends Exception
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{
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private List<Throwable> nested;
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boolean superConstructorCalled = false;
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/* ------------------------------------------------------------ */
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public MultiException()
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{
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super("Multiple exceptions");
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this.superConstructorCalled = true;
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}
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/**
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* We only want to fill in the stack trace if we have an exception to throw.
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*
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* This prevents the stack trace from being written when the constructor is
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* called, yet will let as fill it in later on e.g. when we actually want
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* to throw the multi exception.
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*/
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@Override
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public Throwable fillInStackTrace() {
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if(superConstructorCalled) {
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return super.fillInStackTrace();
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}
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return this;
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}
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/* ------------------------------------------------------------ */
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@ -105,6 +122,7 @@ public class MultiException extends Exception
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if (th instanceof Exception)
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throw (Exception)th;
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default:
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this.fillInStackTrace();
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throw this;
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}
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}
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@ -137,6 +155,7 @@ public class MultiException extends Exception
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else
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throw new RuntimeException(th);
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default:
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this.fillInStackTrace();
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throw new RuntimeException(this);
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}
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}
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@ -155,7 +174,10 @@ public class MultiException extends Exception
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return;
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if (nested.size()>0)
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{
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this.fillInStackTrace();
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throw this;
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}
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}
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/* ------------------------------------------------------------ */
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@ -21,10 +21,10 @@ package org.eclipse.jetty.util;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertTrue;
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import java.io.IOException;
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import org.junit.Test;
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import java.io.IOException;
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public class MultiExceptionTest
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{
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@ -37,6 +37,8 @@ public class MultiExceptionTest
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me.ifExceptionThrow();
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me.ifExceptionThrowMulti();
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me.ifExceptionThrowRuntime();
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assertEquals("Stack trace should not be filled out", 0, me.getStackTrace().length);
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}
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@Test
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@ -91,19 +93,26 @@ public class MultiExceptionTest
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{
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assertTrue(run==e);
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}
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assertEquals("Stack trace should not be filled out", 0, me.getStackTrace().length);
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}
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@Test
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public void testTwo() throws Exception
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{
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private MultiException multiExceptionWithTwo() {
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MultiException me = new MultiException();
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IOException io = new IOException("one");
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RuntimeException run = new RuntimeException("one");
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me.add(io);
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me.add(run);
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assertEquals(2,me.size());
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assertEquals("Stack trace should not be filled out", 0, me.getStackTrace().length);
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return me;
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}
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@Test
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public void testTwo() throws Exception
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{
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MultiException me = multiExceptionWithTwo();
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try
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{
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me.ifExceptionThrow();
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@ -112,8 +121,10 @@ public class MultiExceptionTest
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catch(MultiException e)
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{
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assertTrue(e==me);
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assertTrue(e.getStackTrace().length > 0);
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}
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me = multiExceptionWithTwo();
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try
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{
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me.ifExceptionThrowMulti();
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@ -122,8 +133,10 @@ public class MultiExceptionTest
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catch(MultiException e)
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{
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assertTrue(e==me);
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assertTrue(e.getStackTrace().length > 0);
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}
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me = multiExceptionWithTwo();
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try
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{
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me.ifExceptionThrowRuntime();
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@ -132,8 +145,10 @@ public class MultiExceptionTest
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catch(RuntimeException e)
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{
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assertTrue(e.getCause()==me);
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assertTrue(e.getStackTrace().length > 0);
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}
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RuntimeException run = new RuntimeException("one");
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me = new MultiException();
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me.add(run);
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me.add(run);
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@ -146,6 +161,7 @@ public class MultiExceptionTest
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catch(RuntimeException e)
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{
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assertTrue(e.getCause()==me);
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assertTrue(e.getStackTrace().length > 0);
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}
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}
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