org.apache.logging.log4j.spi.MutableThreadContextStack Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you 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.apache.logging.log4j.spi;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import org.apache.logging.log4j.ThreadContext.ContextStack;
import org.apache.logging.log4j.util.StringBuilderFormattable;
/**
* TODO
*/
public class MutableThreadContextStack implements ThreadContextStack, StringBuilderFormattable {
private static final long serialVersionUID = 50505011L;
/**
* The underlying list (never null).
*/
private final List list;
private boolean frozen;
/**
* Constructs an empty MutableThreadContextStack.
*/
public MutableThreadContextStack() {
this(new ArrayList());
}
/**
* Constructs a new instance.
* @param list Initial elements to be stored in this stack implementation.
*/
public MutableThreadContextStack(final List list) {
this.list = new ArrayList<>(list);
}
private MutableThreadContextStack(final MutableThreadContextStack stack) {
this.list = new ArrayList<>(stack.list);
}
private void checkInvariants() {
if (frozen) {
throw new UnsupportedOperationException("context stack has been frozen");
}
}
@Override
public String pop() {
checkInvariants();
if (list.isEmpty()) {
return null;
}
final int last = list.size() - 1;
final String result = list.remove(last);
return result;
}
@Override
public String peek() {
if (list.isEmpty()) {
return null;
}
final int last = list.size() - 1;
return list.get(last);
}
@Override
public void push(final String message) {
checkInvariants();
list.add(message);
}
@Override
public int getDepth() {
return list.size();
}
@Override
public List asList() {
return list;
}
@Override
public void trim(final int depth) {
checkInvariants();
if (depth < 0) {
throw new IllegalArgumentException("Maximum stack depth cannot be negative");
}
if (list == null) {
return;
}
final List copy = new ArrayList<>(list.size());
final int count = Math.min(depth, list.size());
for (int i = 0; i < count; i++) {
copy.add(list.get(i));
}
list.clear();
list.addAll(copy);
}
@Override
public ThreadContextStack copy() {
return new MutableThreadContextStack(this);
}
@Override
public void clear() {
checkInvariants();
list.clear();
}
@Override
public int size() {
return list.size();
}
@Override
public boolean isEmpty() {
return list.isEmpty();
}
@Override
public boolean contains(final Object o) {
return list.contains(o);
}
@Override
public Iterator iterator() {
return list.iterator();
}
@Override
public Object[] toArray() {
return list.toArray();
}
@Override
public T[] toArray(final T[] ts) {
return list.toArray(ts);
}
@Override
public boolean add(final String s) {
checkInvariants();
return list.add(s);
}
@Override
public boolean remove(final Object o) {
checkInvariants();
return list.remove(o);
}
@Override
public boolean containsAll(final Collection objects) {
return list.containsAll(objects);
}
@Override
public boolean addAll(final Collection strings) {
checkInvariants();
return list.addAll(strings);
}
@Override
public boolean removeAll(final Collection objects) {
checkInvariants();
return list.removeAll(objects);
}
@Override
public boolean retainAll(final Collection objects) {
checkInvariants();
return list.retainAll(objects);
}
@Override
public String toString() {
return String.valueOf(list);
}
@Override
public void formatTo(final StringBuilder buffer) {
buffer.append('[');
for (int i = 0; i < list.size(); i++) {
if (i > 0) {
buffer.append(',').append(' ');
}
buffer.append(list.get(i));
}
buffer.append(']');
}
@Override
public int hashCode() {
return 31 + Objects.hashCode(list);
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof ThreadContextStack)) {
return false;
}
final ThreadContextStack other = (ThreadContextStack) obj;
final List otherAsList = other.asList();
return Objects.equals(this.list, otherAsList);
}
@Override
public ContextStack getImmutableStackOrNull() {
return copy();
}
/**
* "Freezes" this context stack so it becomes immutable: all mutator methods will throw an exception from now on.
*/
public void freeze() {
frozen = true;
}
/**
* Returns whether this context stack is frozen.
* @return whether this context stack is frozen.
*/
public boolean isFrozen() {
return frozen;
}
}