/*
* Copyright 2012-2017 the original author or authors.
*
* Licensed 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.springframework.boot.actuate.metrics.export;
import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.actuate.metrics.Metric;
import org.springframework.util.StringUtils;
/**
* Base class for metric exporters that have common features, principally a prefix for
* exported metrics and filtering by timestamp (so only new values are included in the
* export).
*
* @author Dave Syer
* @since 1.3.0
*/
public abstract class AbstractMetricExporter implements Exporter, Closeable, Flushable {
private static final Log logger = LogFactory.getLog(AbstractMetricExporter.class);
private final String prefix;
private Date earliestTimestamp = new Date();
private boolean ignoreTimestamps = false;
private boolean sendLatest = true;
private volatile AtomicBoolean processing = new AtomicBoolean(false);
private Date latestTimestamp = new Date(0L);
public AbstractMetricExporter(String prefix) {
this.prefix = (!StringUtils.hasText(prefix) ? ""
: (prefix.endsWith(".") ? prefix : prefix + "."));
}
/**
* The earliest time for which data will be exported.
* @param earliestTimestamp the timestamp to set
*/
public void setEarliestTimestamp(Date earliestTimestamp) {
this.earliestTimestamp = earliestTimestamp;
}
/**
* Ignore timestamps (export all metrics).
* @param ignoreTimestamps the flag to set
*/
public void setIgnoreTimestamps(boolean ignoreTimestamps) {
this.ignoreTimestamps = ignoreTimestamps;
}
/**
* Send only the data that changed since the last export.
* @param sendLatest the flag to set
*/
public void setSendLatest(boolean sendLatest) {
this.sendLatest = sendLatest;
}
@Override
public void export() {
if (this.processing.compareAndSet(false, true)) {
long latestTimestamp = System.currentTimeMillis();
try {
exportGroups();
}
catch (Exception ex) {
logger.warn("Could not write to MetricWriter: " + ex.getClass() + ": "
+ ex.getMessage());
}
finally {
this.latestTimestamp = new Date(latestTimestamp);
flushQuietly();
this.processing.set(false);
}
}
}
private void exportGroups() {
for (String group : groups()) {
Collection<Metric<?>> values = new ArrayList<>();
for (Metric<?> metric : next(group)) {
Date timestamp = metric.getTimestamp();
if (canExportTimestamp(timestamp)) {
values.add(getPrefixedMetric(metric));
}
}
if (!values.isEmpty()) {
write(group, values);
}
}
}
private Metric<?> getPrefixedMetric(Metric<?> metric) {
String name = this.prefix + metric.getName();
return new Metric<Number>(name, metric.getValue(), metric.getTimestamp());
}
private boolean canExportTimestamp(Date timestamp) {
if (this.ignoreTimestamps) {
return true;
}
if (this.earliestTimestamp.after(timestamp)) {
return false;
}
if (this.sendLatest && this.latestTimestamp.after(timestamp)) {
return false;
}
return true;
}
private void flushQuietly() {
try {
flush();
}
catch (Exception ex) {
logger.warn("Could not flush MetricWriter: " + ex.getClass() + ": "
+ ex.getMessage());
}
}
@Override
public void close() throws IOException {
export();
flushQuietly();
}
@Override
public void flush() {
}
/**
* Generate a group of metrics to iterate over in the form of a set of Strings (e.g.
* prefixes). If the metrics to be exported partition into groups identified by a
* String, subclasses should override this method. Otherwise the default should be
* fine (iteration over all metrics).
* @return groups of metrics to iterate over (default singleton empty string)
*/
protected Iterable<String> groups() {
return Collections.singleton("");
}
/**
* Write the values associated with a group.
* @param group the group to write
* @param values the values to write
*/
protected abstract void write(String group, Collection<Metric<?>> values);
/**
* Get the next group of metrics to write.
* @param group the group name to write
* @return some metrics to write
*/
protected abstract Iterable<Metric<?>> next(String group);
}