org.apache.logging.log4j.spi.ReadOnlyThreadContextMap Maven / Gradle / Ivy
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* 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.Map;
import org.apache.logging.log4j.ThreadContext;
import org.apache.logging.log4j.util.StringMap;
/**
* Read-only view of the data structure that implements MDC behavior for {@link org.apache.logging.log4j.ThreadContext}.
*
* {@code ThreadContextMap} implementations that also implement this interface can be accessed
* by applications via the {@link ThreadContext#getThreadContextMap()} method.
*
* Warning: part of the API, not the SPI, since it is used by {@link ThreadContext#getThreadContextMap()}.
*
* @see ThreadContext#getThreadContextMap()
* @since 2.8
*/
public interface ReadOnlyThreadContextMap {
/**
* Clears the context.
*/
void clear();
/**
* Determines if the key is in the context.
* @param key The key to locate.
* @return True if the key is in the context, false otherwise.
*/
boolean containsKey(final String key);
/**
* Gets the context identified by the key parameter.
*
* This method has no side effects.
* @param key The key to locate.
* @return The value associated with the key or null.
*/
String get(final String key);
/**
* Gets a non-{@code null} mutable copy of current thread's context Map.
* @return a mutable copy of the context.
*/
Map getCopy();
/**
* Returns an immutable view on the context Map or {@code null} if the context map is empty.
* @return an immutable context Map or {@code null}.
*/
Map getImmutableMapOrNull();
/**
* Returns the context data for reading. Note that regardless of whether the returned context data has been
* {@linkplain StringMap#freeze() frozen} (made read-only) or not, callers should not attempt to modify
* the returned data structure.
*
* Thread safety note:
*
*
* If this {@code ReadOnlyThreadContextMap} implements {@link CopyOnWrite}, then the returned {@code StringMap} can
* safely be passed to another thread: future changes in the underlying context data will not be reflected in the
* returned {@code StringMap}.
*
* Otherwise, if this {@code ReadOnlyThreadContextMap} does not implement {@link CopyOnWrite}, then it is
* not safe to pass the returned {@code StringMap} to another thread because changes in the underlying context may
* be reflected in the returned object. It is the responsibility of the caller to make a copy to pass to another
* thread.
*
*
* @return a {@code StringMap} containing context data key-value pairs
*/
StringMap getReadOnlyContextData();
/**
* Returns true if the Map is empty.
* @return true if the Map is empty, false otherwise.
*/
boolean isEmpty();
}