Remove RecursiveObjectLeaker

This is a remnant of infrastructure needed to make circular object
graphs work. It has been deprecated for removal in version 7.0.0, now
remove it.

JIRA: YANGTOOLS-1318
Change-Id: I8f6590b5398317a6c24d4b06956161b747795de6
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>

diff --git a/common/util/src/main/java/org/opendaylight/yangtools/util/RecursiveObjectLeaker.java b/common/util/src/main/java/org/opendaylight/yangtools/util/RecursiveObjectLeaker.java
deleted file mode 100644 (file)
index 14ede64..0000000
--- a/common/util/src/main/java/org/opendaylight/yangtools/util/RecursiveObjectLeaker.java
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
- * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Public License v1.0 which accompanies this distribution,
- * and is available at http://www.eclipse.org/legal/epl-v10.html
- */
-package org.opendaylight.yangtools.util;
-
-import static com.google.common.base.Preconditions.checkState;
-
-import com.google.common.annotations.Beta;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.ArrayDeque;
-import java.util.Deque;
-import java.util.Map.Entry;
-import org.eclipse.jdt.annotation.Nullable;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * Thread-local hack to make recursive extensions work without too much hassle. The idea is that prior to instantiating
- * an extension, the definition object checks whether it is already present on the stack, recorded object is returned.
- *
- * <p>
- * If it is not, it will push itself to the stack as unresolved and invoke the constructor. The constructor's lowermost
- * class calls to this class and if the topmost entry is not resolved, it will leak itself.
- *
- * <p>
- * Upon return from the constructor, the topmost entry is removed and if the queue is empty, the thread-local variable
- * will be cleaned up.
- *
- * <p>
- * WARNING: BE CAREFUL WHEN USING THIS CLASS. IT LEAKS OBJECTS WHICH ARE NOT COMPLETELY INITIALIZED.
- *
- * <p>
- * WARNING: THIS CLASS LEAVES THREAD-LOCAL RESIDUE. MAKE SURE IT IS OKAY OR CALL {@link #cleanup()} IN APPROPRIATE
- *          PLACES.
- *
- * <p>
- * THIS CLASS IS EXTREMELY DANGEROUS (okay, not as much as sun.misc.unsafe). YOU HAVE BEEN WARNED. IF SOMETHING BREAKS
- * IT IS PROBABLY YOUR FAULT AND YOU ARE ON YOUR OWN.
- *
- * @author Robert Varga
- * @deprecated This class is not used anywhere anymore and is scheduled for removal in the next major release.
- */
-@Beta
-@Deprecated(forRemoval = true)
-// FIXME: 8.0.0: remove this class
-public final class RecursiveObjectLeaker {
-    // Logging note. Only keys passed can be logged, as objects beng resolved may not be properly constructed.
-    private static final Logger LOG = LoggerFactory.getLogger(RecursiveObjectLeaker.class);
-
-    // Initial value is set to null on purpose, so we do not allocate anything (aside the map)
-    private static final ThreadLocal<Deque<Entry<?, Object>>> STACK = new ThreadLocal<>();
-
-    private RecursiveObjectLeaker() {
-        // Hidden on purpose
-    }
-
-    // Key is checked for identity
-    public static void beforeConstructor(final Object key) {
-        Deque<Entry<?, Object>> stack = STACK.get();
-        if (stack == null) {
-            // Biased: this class is expected to be rarely and shallowly used
-            stack = new ArrayDeque<>(1);
-            STACK.set(stack);
-        }
-
-        LOG.debug("Resolving key {}", key);
-        stack.push(new SimpleEntry<>(key, null));
-    }
-
-    // Can potentially store a 'null' mapping. Make sure cleanup() is called
-    public static void inConstructor(final Object obj) {
-        final Deque<Entry<?, Object>> stack = STACK.get();
-        if (stack != null) {
-            final Entry<?, Object> top = stack.peek();
-            if (top != null) {
-                if (top.getValue() == null) {
-                    LOG.debug("Resolved key {}", top.getKey());
-                    top.setValue(obj);
-                }
-            } else {
-                LOG.info("Cleaned stale empty stack", new Exception());
-                STACK.set(null);
-            }
-        } else {
-            LOG.trace("No thread stack");
-        }
-    }
-
-    // Make sure to call this from a finally block
-    public static void afterConstructor(final Object key) {
-        final Deque<Entry<?, Object>> stack = STACK.get();
-        checkState(stack != null, "No stack allocated when completing %s", key);
-
-        final Entry<?, Object> top = stack.pop();
-        if (stack.isEmpty()) {
-            LOG.trace("Removed empty thread stack");
-            STACK.set(null);
-        }
-
-        checkState(key == top.getKey(), "Expected key %s, have %s", top.getKey(), key);
-        checkState(top.getValue() != null, "");
-    }
-
-    // BEWARE: this method returns incpmpletely-initialized objects (that is the purpose of this class).
-    //
-    //         BE VERY CAREFUL WHAT OBJECT STATE YOU TOUCH
-    public static <T> @Nullable T lookup(final Object key, final Class<T> requiredClass) {
-        final Deque<Entry<?, Object>> stack = STACK.get();
-        if (stack != null) {
-            for (Entry<?, Object> e : stack) {
-                // Keys are treated as identities
-                if (key == e.getKey()) {
-                    checkState(e.getValue() != null, "Object for %s is not resolved", key);
-                    LOG.debug("Looked up key {}", e.getKey());
-                    return requiredClass.cast(e.getValue());
-                }
-            }
-        }
-
-        return null;
-    }
-
-    // Be sure to call this in from a finally block when bulk processing is done, so that this class can be unloaded
-    public static void cleanup() {
-        STACK.remove();
-        LOG.debug("Removed thread state");
-    }
-}