/**
* Copyright 2013 Netflix, Inc.
*
* 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 com.netflix.servo.publish;
import com.google.common.base.Strings;
import com.netflix.servo.monitor.MonitorConfig;
import com.netflix.servo.tag.Tag;
import com.netflix.servo.tag.TagList;
import java.util.Map;
import java.util.NavigableMap;
/**
* Filter that checks for a prefix match on a given tag. This can be useful
* providing rules associated with the canonical class name.
*/
public final class PrefixMetricFilter implements MetricFilter {
private final String tagKey;
private final MetricFilter root;
private final NavigableMap<String, MetricFilter> filters;
/**
* Creates a new prefix filter.
*
* @param tagKey the tag to perform matching on, if null the name will be
* checked
* @param root filter used if there are no prefix matches
* @param filters map of prefix to sub-filter. The filter associated with
* the longest matching prefix will be used.
*/
public PrefixMetricFilter(
String tagKey,
MetricFilter root,
NavigableMap<String, MetricFilter> filters) {
this.tagKey = tagKey;
this.root = root;
this.filters = filters;
}
/** {@inheritDoc} */
public boolean matches(MonitorConfig config) {
String name = config.getName();
TagList tags = config.getTags();
String value;
if (tagKey == null) {
value = name;
} else {
Tag t = tags.getTag(tagKey);
value = (t == null) ? null : t.getValue();
}
if (Strings.isNullOrEmpty(value)) {
return root.matches(config);
} else {
String start = value.substring(0, 1);
NavigableMap<String, MetricFilter> candidates =
filters.subMap(start, true, value, true).descendingMap();
if (candidates.isEmpty()) {
return root.matches(config);
} else {
for (Map.Entry<String, MetricFilter> e : candidates.entrySet()) {
if (value.startsWith(e.getKey())) {
return e.getValue().matches(config);
}
}
return root.matches(config);
}
}
}
}