LUCENE-7409: improve MockDirectoryWrapper's IndexInput to detect if a clone is being used after its parent was closed

lucene/test-framework/src/java/org/apache/lucene/store/MockDirectoryWrapper.java

@@ -771,7 +771,7 @@ public class MockDirectoryWrapper extends BaseDirectoryWrapper {
       }
       ii = new SlowOpeningMockIndexInputWrapper(this, name, delegateInput);
     } else {
-      ii = new MockIndexInputWrapper(this, name, delegateInput);
+      ii = new MockIndexInputWrapper(this, name, delegateInput, null);
     }
     addFileHandle(ii, name, Handle.Input);
     return ii;

lucene/test-framework/src/java/org/apache/lucene/store/MockIndexInputWrapper.java

@@ -30,12 +30,19 @@ public class MockIndexInputWrapper extends IndexInput {
   private MockDirectoryWrapper dir;
   final String name;
   private IndexInput delegate;
-  private boolean isClone;
-  private boolean closed;
+  private volatile boolean closed;
 
-  /** Construct an empty output buffer. */
-  public MockIndexInputWrapper(MockDirectoryWrapper dir, String name, IndexInput delegate) {
+  // Which MockIndexInputWrapper we were cloned from, or null if we are not a clone:
+  private final MockIndexInputWrapper parent;
+  
+  /** Sole constructor */
+  public MockIndexInputWrapper(MockDirectoryWrapper dir, String name, IndexInput delegate, MockIndexInputWrapper parent) {
     super("MockIndexInputWrapper(name=" + name + " delegate=" + delegate + ")");
+
+    // If we are a clone then our parent better not be a clone!
+    assert parent == null || parent.parent == null;
+    
+    this.parent = parent;
     this.name = name;
     this.dir = dir;
     this.delegate = delegate;
@@ -54,7 +61,7 @@ public class MockIndexInputWrapper extends IndexInput {
       // remove the conditional check so we also track that
       // all clones get closed:
       assert delegate != null;
-      if (!isClone) {
+      if (parent == null) {
         dir.removeIndexInput(this, name);
       }
       dir.maybeThrowDeterministicException();
@@ -62,9 +69,13 @@ public class MockIndexInputWrapper extends IndexInput {
   }
   
   private void ensureOpen() {
+    // TODO: not great this is a volatile read (closed) ... we should deploy heavy JVM voodoo like SwitchPoint to avoid this
     if (closed) {
       throw new RuntimeException("Abusing closed IndexInput!");
     }
+    if (parent != null && parent.closed) {
+      throw new RuntimeException("Abusing clone of a closed IndexInput!");
+    }
   }
 
   @Override
@@ -75,8 +86,7 @@ public class MockIndexInputWrapper extends IndexInput {
     }
     dir.inputCloneCount.incrementAndGet();
     IndexInput iiclone = delegate.clone();
-    MockIndexInputWrapper clone = new MockIndexInputWrapper(dir, name, iiclone);
-    clone.isClone = true;
+    MockIndexInputWrapper clone = new MockIndexInputWrapper(dir, name, iiclone, parent != null ? parent : this);
     // Pending resolution on LUCENE-686 we may want to
     // uncomment this code so that we also track that all
     // clones get closed:
@@ -102,8 +112,7 @@ public class MockIndexInputWrapper extends IndexInput {
     }
     dir.inputCloneCount.incrementAndGet();
     IndexInput slice = delegate.slice(sliceDescription, offset, length);
-    MockIndexInputWrapper clone = new MockIndexInputWrapper(dir, sliceDescription, slice);
-    clone.isClone = true;
+    MockIndexInputWrapper clone = new MockIndexInputWrapper(dir, sliceDescription, slice, parent != null ? parent : this);
     return clone;
   }
 

lucene/test-framework/src/java/org/apache/lucene/store/SlowClosingMockIndexInputWrapper.java

@@ -30,7 +30,7 @@ class SlowClosingMockIndexInputWrapper extends MockIndexInputWrapper {
 
   public SlowClosingMockIndexInputWrapper(MockDirectoryWrapper dir,
       String name, IndexInput delegate) {
-    super(dir, name, delegate);
+    super(dir, name, delegate, null);
   }
   
   @Override

lucene/test-framework/src/java/org/apache/lucene/store/SlowOpeningMockIndexInputWrapper.java

@@ -28,7 +28,7 @@ class SlowOpeningMockIndexInputWrapper extends MockIndexInputWrapper {
 
   public SlowOpeningMockIndexInputWrapper(MockDirectoryWrapper dir,
       String name, IndexInput delegate) throws IOException {
-    super(dir, name, delegate);
+    super(dir, name, delegate, null);
     try {
       Thread.sleep(50);
     } catch (InterruptedException ie) {

lucene/test-framework/src/test/org/apache/lucene/store/TestMockDirectoryWrapper.java

@@ -171,4 +171,40 @@ public class TestMockDirectoryWrapper extends BaseDirectoryTestCase {
 
     assertTrue("MockDirectoryWrapper on dir=" + dir + " failed to corrupt an unsync'd file", changed);
   }
+
+  public void testAbuseClosedIndexInput() throws Exception {
+    MockDirectoryWrapper dir = newMockDirectory();
+    IndexOutput out = dir.createOutput("foo", IOContext.DEFAULT);
+    out.writeByte((byte) 42);
+    out.close();
+    final IndexInput in = dir.openInput("foo", IOContext.DEFAULT);
+    in.close();
+    expectThrows(RuntimeException.class, () -> {in.readByte();});
+    dir.close();
+  }
+
+  public void testAbuseCloneAfterParentClosed() throws Exception {
+    MockDirectoryWrapper dir = newMockDirectory();
+    IndexOutput out = dir.createOutput("foo", IOContext.DEFAULT);
+    out.writeByte((byte) 42);
+    out.close();
+    IndexInput in = dir.openInput("foo", IOContext.DEFAULT);
+    final IndexInput clone = in.clone();
+    in.close();
+    expectThrows(RuntimeException.class, () -> {clone.readByte();});
+    dir.close();
+  }
+
+  public void testAbuseCloneOfCloneAfterParentClosed() throws Exception {
+    MockDirectoryWrapper dir = newMockDirectory();
+    IndexOutput out = dir.createOutput("foo", IOContext.DEFAULT);
+    out.writeByte((byte) 42);
+    out.close();
+    IndexInput in = dir.openInput("foo", IOContext.DEFAULT);
+    IndexInput clone1 = in.clone();
+    IndexInput clone2 = clone1.clone();
+    in.close();
+    expectThrows(RuntimeException.class, () -> {clone2.readByte();});
+    dir.close();
+  }
 }