Java tutorial
/** * Copyright 2014 Groupon.com * * 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.arpnetworking.tsdaggregator.sources; import com.arpnetworking.tsdaggregator.model.DefaultMetric; import com.arpnetworking.tsdaggregator.model.DefaultRecord; import com.arpnetworking.tsdaggregator.model.Metric; import com.arpnetworking.tsdaggregator.model.MetricType; import com.arpnetworking.tsdaggregator.model.Record; import com.arpnetworking.tsdcore.model.Quantity; import com.arpnetworking.tsdcore.sources.BaseSource; import com.arpnetworking.tsdcore.sources.Source; import com.arpnetworking.utility.OvalBuilder; import com.arpnetworking.utility.observer.Observable; import com.arpnetworking.utility.observer.Observer; import com.google.common.base.MoreObjects; import com.google.common.collect.ImmutableList; import com.google.common.collect.Lists; import com.google.common.collect.Maps; import net.sf.oval.constraint.NotNull; import org.apache.log4j.Logger; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * Implementation of <code>Source</code> which wraps another <code>Source</code> * and merges <code>Metric</code> instances within each <code>Record</code> * together if the name matches a regular expression with a new name generated * through replacement of all matches in the original name. * * @author Ville Koskela (vkoskela at groupon dot com) */ public final class MappingSource extends BaseSource { /** * {@inheritDoc} */ @Override public void start() { _source.start(); } /** * {@inheritDoc} */ @Override public void stop() { _source.stop(); } /** * {@inheritDoc} */ @Override public String toString() { return MoreObjects.toStringHelper(this).add("super", super.toString()).add("Source", _source).toString(); } private MappingSource(final Builder builder) { super(builder); _source = builder._source; _findAndReplace = Maps.newHashMapWithExpectedSize(builder._findAndReplace.size()); for (final Map.Entry<String, ? extends List<String>> entry : builder._findAndReplace.entrySet()) { _findAndReplace.put(Pattern.compile(entry.getKey()), ImmutableList.<String>copyOf(entry.getValue())); } _source.attach(new MappingObserver(this, _findAndReplace)); } private final Source _source; private final Map<Pattern, List<String>> _findAndReplace; private static final Logger LOGGER = Logger.getLogger(MappingSource.class); // NOTE: Package private for testing /* package private */ static final class MappingObserver implements Observer { public MappingObserver(final MappingSource source, final Map<Pattern, List<String>> findAndReplace) { _source = source; _findAndReplace = findAndReplace; } @Override public void notify(final Observable observable, final Object event) { if (!(event instanceof Record)) { LOGGER.error(String.format("Observed unsupported event; event=%s", event)); return; } // Merge the metrics in the record together final Record record = (Record) event; final Map<String, MergingMetric> mergedMetrics = Maps.newHashMap(); for (final Map.Entry<String, ? extends Metric> metric : record.getMetrics().entrySet()) { boolean found = false; for (final Map.Entry<Pattern, List<String>> findAndReplace : _findAndReplace.entrySet()) { final Matcher matcher = findAndReplace.getKey().matcher(metric.getKey()); if (matcher.find()) { for (final String replacement : findAndReplace.getValue()) { merge(metric.getValue(), matcher.replaceAll(replacement), mergedMetrics); } //Having "found" set here means that mapping a metric to an empty list suppresses that metric found = true; } } if (!found) { merge(metric.getValue(), metric.getKey(), mergedMetrics); } } // Raise the merged record event with this source's observers // NOTE: Do not leak instances of MergingMetric since it is mutable _source.notify(new DefaultRecord.Builder().setMetrics(Maps.transformEntries(mergedMetrics, new Maps.EntryTransformer<String, MergingMetric, Metric>() { @Override public Metric transformEntry(final String key, final MergingMetric mergingMetric) { return OvalBuilder.clone(mergingMetric, new DefaultMetric.Builder()).build(); } })).setTime(record.getTime()).setAnnotations(record.getAnnotations()).build()); } private void merge(final Metric metric, final String key, final Map<String, MergingMetric> mergedMetrics) { final MergingMetric mergedMetric = mergedMetrics.get(key); if (mergedMetric == null) { // This is the first time this metric is being merged into mergedMetrics.put(key, new MergingMetric(metric)); } else if (!mergedMetric.isMergable(metric)) { // This instance of the metric is not mergable with previous LOGGER.error(String.format("Discarding metric, failed to merge; metric=%s mergedMetric=%s", metric, mergedMetric)); } else { // Merge the new instance in mergedMetric.merge(metric); } } private final MappingSource _source; private final Map<Pattern, List<String>> _findAndReplace; } // NOTE: Package private for testing /* package private */static final class MergingMetric implements Metric { public MergingMetric(final Metric metric) { _type = metric.getType(); _values = Lists.newArrayList(metric.getValues()); } public boolean isMergable(final Metric metric) { return _type.equals(metric.getType()); } public void merge(final Metric metric) { if (!isMergable(metric)) { throw new IllegalArgumentException(String.format("Metric cannot be merged; metric=%s", metric)); } _values.addAll(metric.getValues()); } @Override public MetricType getType() { return _type; } @Override public List<Quantity> getValues() { return Collections.unmodifiableList(_values); } @Override public String toString() { return MoreObjects.toStringHelper(this).add("Type", _type).add("Values", _values).toString(); } private final MetricType _type; private final List<Quantity> _values; } /** * Implementation of builder pattern for <code>FileSource</code>. * * @author Ville Koskela (vkoskela at groupon dot com) */ public static final class Builder extends BaseSource.Builder<Builder> { /** * Public constructor. */ public Builder() { super(MappingSource.class); } /** * Sets the underlying source. Cannot be null. * * @param value The underlying source. * @return This instance of <code>Builder</code>. */ public Builder setSource(final Source value) { _source = value; return this; } /** * Sets find and replace expression map. Cannot be null. * * @param value The find and replace expression map. * @return This instance of <code>Builder</code>. */ public Builder setFindAndReplace(final Map<String, ? extends List<String>> value) { _findAndReplace = value; return this; } /** * {@inheritDoc} */ @Override protected Builder self() { return this; } @NotNull private Source _source; @NotNull private Map<String, ? extends List<String>> _findAndReplace; } }