[LOGMGR-130] Extract log level init task to a separate class which ca…

…n be overridden for Java 9

src/main/java/org/jboss/logmanager/LogLevelInitTask.java

@@ -0,0 +1,390 @@
+/*
+ * JBoss, Home of Professional Open Source.
+ * Copyright 2017 Red Hat, Inc., and individual contributors
+ * as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jboss.logmanager;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.security.PrivilegedAction;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.Map;
+
+/**
+ */
+class LogLevelInitTask implements PrivilegedAction<Void> {
+    LogLevelInitTask() {
+    }
+
+    @SuppressWarnings({ "unchecked" })
+    public Void run() {
+        /* This mysterious-looking hack is designed to trick JDK logging into not leaking classloaders and
+           so forth when adding levels, by simply shutting down the craptastic level name "registry" that it keeps.
+        */
+        final Class<java.util.logging.Level> lc = java.util.logging.Level.class;
+        try {
+            synchronized (lc) {
+                final Field knownField = lc.getDeclaredField("known");
+                knownField.setAccessible(true);
+                final List<java.util.logging.Level> old = (List<java.util.logging.Level>) knownField.get(null);
+                if (! (old instanceof ReadOnlyArrayList)) {
+                    knownField.set(null, new ReadOnlyArrayList<java.util.logging.Level>(Arrays.asList(
+                        Level.TRACE,
+                        Level.DEBUG,
+                        Level.INFO,
+                        Level.WARN,
+                        Level.ERROR,
+                        Level.FATAL,
+                        java.util.logging.Level.ALL,
+                        java.util.logging.Level.FINEST,
+                        java.util.logging.Level.FINER,
+                        java.util.logging.Level.FINE,
+                        java.util.logging.Level.INFO,
+                        java.util.logging.Level.CONFIG,
+                        java.util.logging.Level.WARNING,
+                        java.util.logging.Level.SEVERE,
+                        java.util.logging.Level.OFF
+                    )));
+                }
+            }
+        } catch (Throwable e) {
+            // ignore; just don't install
+        }
+
+        // OpenJDK uses a KnownLevel inner class with two static maps
+        try {
+            final Class<?> knownLevelClass = Class.forName("java.util.logging.Level$KnownLevel");
+            synchronized (knownLevelClass) {
+                final Constructor<?> constructor = knownLevelClass.getDeclaredConstructor(java.util.logging.Level.class);
+                constructor.setAccessible(true);
+                boolean doBuild = false;
+                boolean setNameToLevel = false;
+                boolean setIntToLevel = false;
+                // namesToLevels
+                final Field nameToLevels = knownLevelClass.getDeclaredField("nameToLevels");
+                nameToLevels.setAccessible(true);
+                // Current
+                final Map oldNameToLevels = (Map) nameToLevels.get(null);
+                if (! (oldNameToLevels instanceof ReadOnlyHashMap)) {
+                    doBuild = true;
+                    setNameToLevel = true;
+                }
+
+                final Field intToLevels = knownLevelClass.getDeclaredField("intToLevels");
+                intToLevels.setAccessible(true);
+                final Map oldIntToLevels = (Map) intToLevels.get(null);
+                if (! (oldIntToLevels instanceof ReadOnlyHashMap)) {
+                    doBuild = true;
+                    setIntToLevel = true;
+                }
+
+                if (doBuild) {
+                    final KnownLevelBuilder builder = new KnownLevelBuilder(constructor)
+                        .add(Level.TRACE)
+                        .add(Level.DEBUG)
+                        .add(Level.INFO)
+                        .add(Level.WARN)
+                        .add(Level.ERROR)
+                        .add(Level.FATAL)
+                        .add(java.util.logging.Level.ALL)
+                        .add(java.util.logging.Level.FINEST)
+                        .add(java.util.logging.Level.FINER)
+                        .add(java.util.logging.Level.FINE)
+                        .add(java.util.logging.Level.INFO)
+                        .add(java.util.logging.Level.CONFIG)
+                        .add(java.util.logging.Level.WARNING)
+                        .add(java.util.logging.Level.SEVERE)
+                        .add(java.util.logging.Level.OFF);
+
+                    if (setNameToLevel) {
+                        nameToLevels.set(null, builder.toNameMap());
+                    }
+                    if (setIntToLevel) {
+                        intToLevels.set(null, builder.toIntMap());
+                    }
+                }
+            }
+        } catch (Throwable e) {
+            // ignore
+        }
+
+        /* Next hack: the default Sun JMX implementation has a horribly inefficient log implementation which
+           kills performance if a custom logmanager is used.  We'll just blot that out.
+         */
+        try {
+            final Class<?> traceManagerClass = Class.forName("com.sun.jmx.trace.Trace");
+            final Field outField = traceManagerClass.getDeclaredField("out");
+            outField.setAccessible(true);
+            outField.set(null, null);
+        } catch (Throwable e) {
+            // ignore; just skip it
+        }
+        /* Next hack: Replace the crappy MXBean on the system logmanager, if it's there.
+         */
+        final Class<java.util.logging.LogManager> lmc = java.util.logging.LogManager.class;
+        try {
+            synchronized (lmc) {
+                final Field loggingMXBean = lmc.getDeclaredField("loggingMXBean");
+                loggingMXBean.setAccessible(true);
+                loggingMXBean.set(null, LogContext.getSystemLogContext().getLoggingMXBean());
+            }
+        } catch (Throwable e) {
+            // ignore; just skip it
+        }
+        return null;
+    }
+
+    static final class ReadOnlyArrayList<T> extends ArrayList<T> {
+
+        private static final long serialVersionUID = -6048215349511680936L;
+
+        ReadOnlyArrayList(final Collection<? extends T> c) {
+            super(c);
+        }
+
+        static <T> ReadOnlyArrayList<T> of(final Collection<? extends T> c) {
+            return new ReadOnlyArrayList<T>(c);
+        }
+
+        public T set(final int index, final T element) {
+            // ignore
+            return null;
+        }
+
+        public T remove(final int index) {
+            // ignore
+            return null;
+        }
+
+        public boolean remove(final Object o) {
+            // ignore
+            return false;
+        }
+
+        public void clear() {
+            // ignore
+        }
+
+        protected void removeRange(final int fromIndex, final int toIndex) {
+            // ignore
+        }
+
+        public Iterator<T> iterator() {
+            final Iterator<T> superIter = super.iterator();
+            return new Iterator<T>() {
+                public boolean hasNext() {
+                    return superIter.hasNext();
+                }
+
+                public T next() {
+                    return superIter.next();
+                }
+
+                public void remove() {
+                    // ignore
+                }
+            };
+        }
+
+        public ListIterator<T> listIterator(final int index) {
+            final ListIterator<T> superIter = super.listIterator(index);
+            return new ListIterator<T>() {
+                public boolean hasNext() {
+                    return superIter.hasNext();
+                }
+
+                public T next() {
+                    return superIter.next();
+                }
+
+                public boolean hasPrevious() {
+                    return superIter.hasPrevious();
+                }
+
+                public T previous() {
+                    return superIter.previous();
+                }
+
+                public int nextIndex() {
+                    return superIter.nextIndex();
+                }
+
+                public int previousIndex() {
+                    return superIter.previousIndex();
+                }
+
+                public void remove() {
+                    // ignore
+                }
+
+                public void set(final T o) {
+                    // ignore
+                }
+
+                public void add(final T o) {
+                    // ignore
+                }
+            };
+        }
+
+        public boolean removeAll(final Collection<?> c) {
+            // ignore
+            return false;
+        }
+
+        public boolean retainAll(final Collection<?> c) {
+            // ignore
+            return false;
+        }
+    }
+
+    static final class ReadOnlyHashMap<K, V> extends HashMap<K, V> {
+
+        private static final long serialVersionUID = -6048215349511680936L;
+
+        ReadOnlyHashMap(final int size) {
+            super(size);
+        }
+
+        static <K, V> ReadOnlyHashMap<K, V> of(final List<ReadOnlyMapEntry<K, V>> entries) {
+            final ReadOnlyHashMap<K, V> result = new ReadOnlyHashMap<K, V>(entries.size());
+            for (ReadOnlyMapEntry<K, V> entry : entries) {
+                result.add(entry.getKey(), entry.getValue());
+            }
+            return result;
+        }
+
+        private void add(final K key, final V value) {
+            super.put(key, value);
+        }
+
+        @Override
+        public V put(final K key, final V value) {
+            // ignore
+            return null;
+        }
+
+        @Override
+        public void putAll(final Map<? extends K, ? extends V> m) {
+            // ignore
+        }
+
+        @Override
+        public V remove(final Object key) {
+            // ignore
+            return null;
+        }
+
+        @Override
+        public void clear() {
+            // ignore
+        }
+
+        @Override
+        public Collection<V> values() {
+            return new ReadOnlyArrayList<V>(super.values());
+        }
+    }
+
+    static final class ReadOnlyMapEntry<K, V> implements Map.Entry<K, V> {
+
+        private final K key;
+        private final V value;
+
+        private ReadOnlyMapEntry(final K key, final V value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        static <K, V> ReadOnlyMapEntry<K, V> of(final K key, final V value) {
+            return new ReadOnlyMapEntry<K, V>(key, value);
+        }
+
+        @Override
+        public K getKey() {
+            return key;
+        }
+
+        @Override
+        public V getValue() {
+            return value;
+        }
+
+        @Override
+        public V setValue(final V value) {
+            // ignore
+            return null;
+        }
+    }
+
+    static class KnownLevelBuilder {
+        private final Map<String, List<Object>> nameMap;
+        private final Map<Integer, List<Object>> intMap;
+        private final Constructor<?> constructor;
+
+        KnownLevelBuilder(final Constructor<?> constructor) {
+            nameMap = new HashMap<String, List<Object>>();
+            intMap = new HashMap<Integer, List<Object>>();
+            this.constructor = constructor;
+        }
+
+        public KnownLevelBuilder add(final java.util.logging.Level level) throws IllegalAccessException, InvocationTargetException, InstantiationException {
+            final String name = level.getName();
+            final Object knownLevel = constructor.newInstance(level);
+            List<Object> nl = nameMap.get(name);
+            if (nl == null) {
+                nl = new ArrayList<Object>();
+                nameMap.put(name, nl);
+            }
+            nl.add(constructor.newInstance(knownLevel));
+
+            final int intValue = level.intValue();
+            List<Object> il = intMap.get(intValue);
+            if (il == null) {
+                il = new ArrayList<Object>();
+                intMap.put(intValue, il);
+            }
+            il.add(knownLevel);
+            return this;
+        }
+
+        public ReadOnlyHashMap<String, ReadOnlyArrayList<Object>> toNameMap() {
+            final List<ReadOnlyMapEntry<String, ReadOnlyArrayList<Object>>> list =
+                    new ArrayList<ReadOnlyMapEntry<String, ReadOnlyArrayList<Object>>>(nameMap.size());
+            for (String key : nameMap.keySet()) {
+                list.add(ReadOnlyMapEntry.of(key, ReadOnlyArrayList.of(nameMap.get(key))));
+            }
+            return ReadOnlyHashMap.of(list);
+        }
+
+        public ReadOnlyHashMap<Integer, ReadOnlyArrayList<Object>> toIntMap() {
+            final List<ReadOnlyMapEntry<Integer, ReadOnlyArrayList<Object>>> list =
+                    new ArrayList<ReadOnlyMapEntry<Integer, ReadOnlyArrayList<Object>>>(intMap.size());
+            for (Integer key : intMap.keySet()) {
+                list.add(ReadOnlyMapEntry.of(key, ReadOnlyArrayList.of(intMap.get(key))));
+            }
+            return ReadOnlyHashMap.of(list);
+        }
+    }
+}