+/*
+ * 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.log4j.pattern;
+
+import org.apache.log4j.spi.LoggingEvent;
+
+
+/**
+ * Return the relative time in milliseconds since loading of the LoggingEvent
+ * class.
+ *
+ * @author Ceki Gülcü
+ */
+public class RelativeTimePatternConverter extends LoggingEventPatternConverter {
+ /**
+ * Cached formatted timestamp.
+ */
+ private CachedTimestamp lastTimestamp = new CachedTimestamp(0, "");
+
+ /**
+ * Private constructor.
+ */
+ public RelativeTimePatternConverter() {
+ super("Time", "time");
+ }
+
+ /**
+ * Obtains an instance of RelativeTimePatternConverter.
+ * @param options options, currently ignored, may be null.
+ * @return instance of RelativeTimePatternConverter.
+ */
+ public static RelativeTimePatternConverter newInstance(
+ final String[] options) {
+ return new RelativeTimePatternConverter();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public void format(final LoggingEvent event, final StringBuffer toAppendTo) {
+ long timestamp = event.timeStamp;
+
+ if (!lastTimestamp.format(timestamp, toAppendTo)) {
+ final String formatted =
+ Long.toString(timestamp - LoggingEvent.getStartTime());
+ toAppendTo.append(formatted);
+ lastTimestamp = new CachedTimestamp(timestamp, formatted);
+ }
+ }
+
+ /**
+ * Cached timestamp and formatted value.
+ */
+ private static final class CachedTimestamp {
+ /**
+ * Cached timestamp.
+ */
+ private final long timestamp;
+
+ /**
+ * Cached formatted timestamp.
+ */
+ private final String formatted;
+
+ /**
+ * Creates a new instance.
+ * @param timestamp timestamp.
+ * @param formatted formatted timestamp.
+ */
+ public CachedTimestamp(long timestamp, final String formatted) {
+ this.timestamp = timestamp;
+ this.formatted = formatted;
+ }
+
+ /**
+ * Appends the cached formatted timestamp to the buffer if timestamps match.
+ * @param newTimestamp requested timestamp.
+ * @param toAppendTo buffer to append formatted timestamp.
+ * @return true if requested timestamp matched cached timestamp.
+ */
+ public boolean format(long newTimestamp, final StringBuffer toAppendTo) {
+ if (newTimestamp == timestamp) {
+ toAppendTo.append(formatted);
+
+ return true;
+ }
+
+ return false;
+ }
+ }
+}