DiagnosticContextSupplier.java

package com.equalexperts.logging;

import java.util.Map;

/**
 * <p>Provides contextual information for log messages.</p>
 *
 * <p>This is a set of name value pairs that should be
 * added to <i>every</i> log message when available.
 * Two common examples of contextual information are the current username
 * and the current request id.</p>
 *
 * <p>Contextual name-value pairs are only added to log messages when the value is not null or empty.</p>
 * <p>For example, in the case of username, a username=XXX name value pair would not be added to log messages
 * generated by anonymous users, or to background tasks that could not be easily associated with a user.</p>
 */
@FunctionalInterface
public interface DiagnosticContextSupplier {
    /**
     * <p> Provide contextual information about the current log message.</p>
     *
     * <p>This method should generally return a different map each time it is called.
     *
     * <p>A common implementation strategy is to access thread-local information about the current request to build an
     * appropriate map of name-value pairs for each individual request.</p>
     *
     * @return a map of name-value pairs
     */
    Map<String,String> getMessageContext();
}