Java tutorial
/** * This file is part of Graylog. * * Graylog is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Graylog is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Graylog. If not, see <http://www.gnu.org/licenses/>. */ package org.graylog2.indexer.rotation; import org.graylog2.configuration.ElasticsearchConfiguration; import org.graylog2.plugin.Tools; import org.graylog2.plugin.indexer.rotation.RotationStrategy; import org.joda.time.DateTime; import org.joda.time.DateTimeField; import org.joda.time.DateTimeFieldType; import org.joda.time.DateTimeZone; import org.joda.time.Period; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.annotation.Nonnull; import javax.inject.Inject; import javax.inject.Singleton; import java.text.MessageFormat; import static org.joda.time.DateTimeFieldType.*; @Singleton public class TimeBasedRotationStrategy implements RotationStrategy { private static final Logger log = LoggerFactory.getLogger(TimeBasedRotationStrategy.class); private final Period rotationPeriod; private DateTime lastRotation; private DateTime anchor; @Inject public TimeBasedRotationStrategy(ElasticsearchConfiguration configuration) { this(configuration.getMaxTimePerIndex()); } public TimeBasedRotationStrategy(Period rotationPeriod) { this.rotationPeriod = rotationPeriod.normalizedStandard(); anchor = determineRotationPeriodAnchor(rotationPeriod); lastRotation = null; } /** * Determines the starting point ("anchor") for a period. * * To produce repeatable rotation points in time, the period is "snapped" to a "grid" of time. * For example, an hourly index rotation would be anchored to the last full hour, instead of happening at whatever minute * the first rotation was started. * * This "snapping" is done accordingly with the other parts of a period. * * For highly irregular periods (those that do not have a small zero component) * * @param period the rotation period * @return the anchor DateTime to calculate rotation periods from */ protected static DateTime determineRotationPeriodAnchor(Period period) { final Period normalized = period.normalizedStandard(); int years = normalized.getYears(); int months = normalized.getMonths(); int weeks = normalized.getWeeks(); int days = normalized.getDays(); int hours = normalized.getHours(); int minutes = normalized.getMinutes(); int seconds = normalized.getSeconds(); if (years == 0 && months == 0 && weeks == 0 && days == 0 && hours == 0 && minutes == 0 && seconds == 0) { throw new IllegalArgumentException("Invalid rotation period specified"); } // find the largest non-zero stride in the period. that's our anchor type. statement order matters here! DateTimeFieldType largestStrideType = null; if (seconds > 0) largestStrideType = secondOfMinute(); if (minutes > 0) largestStrideType = minuteOfHour(); if (hours > 0) largestStrideType = hourOfDay(); if (days > 0) largestStrideType = dayOfMonth(); if (weeks > 0) largestStrideType = weekOfWeekyear(); if (months > 0) largestStrideType = monthOfYear(); if (years > 0) largestStrideType = year(); if (largestStrideType == null) { throw new IllegalArgumentException("Could not determine rotation stride length."); } final DateTime now = Tools.iso8601(); final DateTimeField field = largestStrideType.getField(now.getChronology()); // use normalized here to make sure we actually have the largestStride type available! see https://github.com/Graylog2/graylog2-server/issues/836 int periodValue = normalized.get(largestStrideType.getDurationType()); final long fieldValue = field.roundFloor(now.getMillis()); final int fieldValueInUnit = field.get(fieldValue); if (periodValue == 0) { // https://github.com/Graylog2/graylog2-server/issues/836 log.warn( "Determining stride length failed because of a 0 period. Defaulting back to 1 period to avoid crashing, but this is a bug!"); periodValue = 1; } final long difference = (fieldValueInUnit % periodValue); final long newValue = field.add(fieldValue, -1 * difference); return new DateTime(newValue, DateTimeZone.UTC); } @Nonnull @Override public Result shouldRotate(String ignored) { // in case we could not determine the last time a time-based rotation was performed, always rotate immediately final DateTime now = Tools.iso8601(); if (lastRotation == null) { lastRotation = now; anchor = determineRotationPeriodAnchor(rotationPeriod); return new SimpleResult(true, "No known previous rotation time, forcing index rotation now."); } final DateTime nextRotation = anchor.plus(rotationPeriod); if (nextRotation.isAfter(now)) { return new SimpleResult(false, MessageFormat.format("Next rotation at {0}", nextRotation)); } // determine new anchor (push it to within less then one period before now) in case we missed one or more periods DateTime tmpAnchor; int multiplicator = 0; do { tmpAnchor = anchor.withPeriodAdded(rotationPeriod, ++multiplicator); } while (tmpAnchor.isBefore(now)); anchor = anchor.withPeriodAdded(rotationPeriod, multiplicator - 1); lastRotation = now; return new SimpleResult(true, MessageFormat.format("Rotation period {0} elapsed, next rotation at {1}", rotationPeriod, anchor)); } private static class SimpleResult implements Result { private final String message; private final boolean rotate; public SimpleResult(boolean rotate, String message) { this.message = message; this.rotate = rotate; log.debug("{} because of: {}", rotate ? "Rotating" : "Not rotating", message); } @Override public String getDescription() { return message; } @Override public boolean shouldRotate() { return rotate; } } }