org.apache.logging.log4j.message.ReusableMessage 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.message;
import org.apache.logging.log4j.util.PerformanceSensitive;
import org.apache.logging.log4j.util.StringBuilderFormattable;
/**
* Messages implementing this interface are reused between logging calls.
*
* If a Message is reusable, downstream components should not hand over this instance to another thread, but extract its
* content (via the {@link StringBuilderFormattable#formatTo(StringBuilder)} method) instead.
*
* @see ReusableMessageFactory
* @since 2.6
*/
@PerformanceSensitive("allocation")
public interface ReusableMessage extends Message, StringBuilderFormattable {
/**
* Returns the parameter array that was used to initialize this reusable message and replaces it with the specified
* array. The returned parameter array will no longer be modified by this reusable message. The specified array is
* now "owned" by this reusable message and can be modified if necessary for the next log event.
*
* ReusableMessages that have no parameters return the specified array.
*
* This method is used by asynchronous loggers to pass the parameter array to a background thread without
* allocating new objects.
* The actual number of parameters in the returned array can be determined with {@link #getParameterCount()}.
*
*
* @param emptyReplacement the parameter array that can be used for subsequent uses of this reusable message.
* This replacement array must have at least 10 elements (the number of varargs supported by the Logger
* API).
* @return the parameter array for the current message content. This may be a vararg array of any length, or it may
* be a reusable array of 10 elements used to hold the unrolled vararg parameters.
* @see #getParameterCount()
*/
Object[] swapParameters(Object[] emptyReplacement);
/**
* Returns the number of parameters that was used to initialize this reusable message for the current content.
*
* The parameter array returned by {@link #swapParameters(Object[])} may be larger than the actual number of
* parameters. Callers should use this method to determine how many elements the array contains.
*
* @return the current number of parameters
*/
short getParameterCount();
/**
* Returns an immutable snapshot of the current internal state of this reusable message. The returned snapshot
* will not be affected by subsequent modifications of this reusable message.
*
* @return an immutable snapshot of this message
*/
Message memento();
}