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/**
* 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.activemq.broker.scheduler;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
import java.util.StringTokenizer;
import javax.jms.MessageFormatException;
public class CronParser {
private static final int NUMBER_TOKENS = 5;
private static final int MINUTES = 0;
private static final int HOURS = 1;
private static final int DAY_OF_MONTH = 2;
private static final int MONTH = 3;
private static final int DAY_OF_WEEK = 4;
public static long getNextScheduledTime(final String cronEntry, long currentTime) throws MessageFormatException {
long result = 0;
if (cronEntry == null || cronEntry.length() == 0) {
return result;
}
// Handle the once per minute case "* * * * *"
// starting the next event at the top of the minute.
if (cronEntry.equals("* * * * *")) {
result = currentTime + 60 * 1000;
result = result / 60000 * 60000;
return result;
}
List list = tokenize(cronEntry);
List entries = buildCronEntries(list);
Calendar working = Calendar.getInstance();
working.setTimeInMillis(currentTime);
working.set(Calendar.SECOND, 0);
CronEntry minutes = entries.get(MINUTES);
CronEntry hours = entries.get(HOURS);
CronEntry dayOfMonth = entries.get(DAY_OF_MONTH);
CronEntry month = entries.get(MONTH);
CronEntry dayOfWeek = entries.get(DAY_OF_WEEK);
// Start at the top of the next minute, cron is only guaranteed to be
// run on the minute.
int timeToNextMinute = 60 - working.get(Calendar.SECOND);
working.add(Calendar.SECOND, timeToNextMinute);
// If its already to late in the day this will roll us over to tomorrow
// so we'll need to check again when done updating month and day.
int currentMinutes = working.get(Calendar.MINUTE);
if (!isCurrent(minutes, currentMinutes)) {
int nextMinutes = getNext(minutes, currentMinutes, working);
working.add(Calendar.MINUTE, nextMinutes);
}
int currentHours = working.get(Calendar.HOUR_OF_DAY);
if (!isCurrent(hours, currentHours)) {
int nextHour = getNext(hours, currentHours, working);
working.add(Calendar.HOUR_OF_DAY, nextHour);
}
// We can roll into the next month here which might violate the cron setting
// rules so we check once then recheck again after applying the month settings.
doUpdateCurrentDay(working, dayOfMonth, dayOfWeek);
// Start by checking if we are in the right month, if not then calculations
// need to start from the beginning of the month to ensure that we don't end
// up on the wrong day. (Can happen when DAY_OF_WEEK is set and current time
// is ahead of the day of the week to execute on).
doUpdateCurrentMonth(working, month);
// Now Check day of week and day of month together since they can be specified
// together in one entry, if both "day of month" and "day of week" are restricted
// (not "*"), then either the "day of month" field (3) or the "day of week" field
// (5) must match the current day or the Calenday must be advanced.
doUpdateCurrentDay(working, dayOfMonth, dayOfWeek);
// Now we can chose the correct hour and minute of the day in question.
currentHours = working.get(Calendar.HOUR_OF_DAY);
if (!isCurrent(hours, currentHours)) {
int nextHour = getNext(hours, currentHours, working);
working.add(Calendar.HOUR_OF_DAY, nextHour);
}
currentMinutes = working.get(Calendar.MINUTE);
if (!isCurrent(minutes, currentMinutes)) {
int nextMinutes = getNext(minutes, currentMinutes, working);
working.add(Calendar.MINUTE, nextMinutes);
}
result = working.getTimeInMillis();
if (result <= currentTime) {
throw new ArithmeticException("Unable to compute next scheduled exection time.");
}
return result;
}
protected static long doUpdateCurrentMonth(Calendar working, CronEntry month) throws MessageFormatException {
int currentMonth = working.get(Calendar.MONTH) + 1;
if (!isCurrent(month, currentMonth)) {
int nextMonth = getNext(month, currentMonth, working);
working.add(Calendar.MONTH, nextMonth);
// Reset to start of month.
resetToStartOfDay(working, 1);
return working.getTimeInMillis();
}
return 0L;
}
protected static long doUpdateCurrentDay(Calendar working, CronEntry dayOfMonth, CronEntry dayOfWeek) throws MessageFormatException {
int currentDayOfWeek = working.get(Calendar.DAY_OF_WEEK) - 1;
int currentDayOfMonth = working.get(Calendar.DAY_OF_MONTH);
// Simplest case, both are unrestricted or both match today otherwise
// result must be the closer of the two if both are set, or the next
// match to the one that is.
if (!isCurrent(dayOfWeek, currentDayOfWeek) ||
!isCurrent(dayOfMonth, currentDayOfMonth) ) {
int nextWeekDay = Integer.MAX_VALUE;
int nextCalendarDay = Integer.MAX_VALUE;
if (!isCurrent(dayOfWeek, currentDayOfWeek)) {
nextWeekDay = getNext(dayOfWeek, currentDayOfWeek, working);
}
if (!isCurrent(dayOfMonth, currentDayOfMonth)) {
nextCalendarDay = getNext(dayOfMonth, currentDayOfMonth, working);
}
if( nextWeekDay < nextCalendarDay ) {
working.add(Calendar.DAY_OF_WEEK, nextWeekDay);
} else {
working.add(Calendar.DAY_OF_MONTH, nextCalendarDay);
}
// Since the day changed, we restart the clock at the start of the day
// so that the next time will either be at 12am + value of hours and
// minutes pattern.
resetToStartOfDay(working, working.get(Calendar.DAY_OF_MONTH));
return working.getTimeInMillis();
}
return 0L;
}
public static void validate(final String cronEntry) throws MessageFormatException {
List list = tokenize(cronEntry);
List entries = buildCronEntries(list);
for (CronEntry e : entries) {
validate(e);
}
}
static void validate(final CronEntry entry) throws MessageFormatException {
List list = entry.currentWhen;
if (list.isEmpty() || list.get(0).intValue() < entry.start || list.get(list.size() - 1).intValue() > entry.end) {
throw new MessageFormatException("Invalid token: " + entry);
}
}
static int getNext(final CronEntry entry, final int current, final Calendar working) throws MessageFormatException {
int result = 0;
if (entry.currentWhen == null) {
entry.currentWhen = calculateValues(entry);
}
List list = entry.currentWhen;
int next = -1;
for (Integer i : list) {
if (i.intValue() > current) {
next = i.intValue();
break;
}
}
if (next != -1) {
result = next - current;
} else {
int first = list.get(0).intValue();
int fixedEnd = entry.end;
//months have different max values
if("DayOfMonth".equals(entry.name)) {
fixedEnd = working.getActualMaximum(Calendar.DAY_OF_MONTH)+1;
}
result = fixedEnd + first - entry.start - current;
// Account for difference of one vs zero based indices.
if (entry.name.equals("DayOfWeek") || entry.name.equals("Month")) {
result++;
}
}
return result;
}
static boolean isCurrent(final CronEntry entry, final int current) throws MessageFormatException {
boolean result = entry.currentWhen.contains(Integer.valueOf(current));
return result;
}
protected static void resetToStartOfDay(Calendar target, int day) {
target.set(Calendar.DAY_OF_MONTH, day);
target.set(Calendar.HOUR_OF_DAY, 0);
target.set(Calendar.MINUTE, 0);
target.set(Calendar.SECOND, 0);
}
static List tokenize(String cron) throws IllegalArgumentException {
StringTokenizer tokenize = new StringTokenizer(cron);
List result = new ArrayList();
while (tokenize.hasMoreTokens()) {
result.add(tokenize.nextToken());
}
if (result.size() != NUMBER_TOKENS) {
throw new IllegalArgumentException("Not a valid cron entry - wrong number of tokens(" + result.size()
+ "): " + cron);
}
return result;
}
protected static List calculateValues(final CronEntry entry) {
List result = new ArrayList();
if (isAll(entry.token)) {
for (int i = entry.start; i <= entry.end; i++) {
result.add(i);
}
} else if (isAStep(entry.token)) {
int denominator = getDenominator(entry.token);
String numerator = getNumerator(entry.token);
CronEntry ce = new CronEntry(entry.name, numerator, entry.start, entry.end);
List list = calculateValues(ce);
for (Integer i : list) {
if (i.intValue() % denominator == 0) {
result.add(i);
}
}
} else if (isAList(entry.token)) {
StringTokenizer tokenizer = new StringTokenizer(entry.token, ",");
while (tokenizer.hasMoreTokens()) {
String str = tokenizer.nextToken();
CronEntry ce = new CronEntry(entry.name, str, entry.start, entry.end);
List list = calculateValues(ce);
result.addAll(list);
}
} else if (isARange(entry.token)) {
int index = entry.token.indexOf('-');
int first = Integer.parseInt(entry.token.substring(0, index));
int last = Integer.parseInt(entry.token.substring(index + 1));
for (int i = first; i <= last; i++) {
result.add(i);
}
} else {
int value = Integer.parseInt(entry.token);
result.add(value);
}
Collections.sort(result);
return result;
}
protected static boolean isARange(String token) {
return token != null && token.indexOf('-') >= 0;
}
protected static boolean isAStep(String token) {
return token != null && token.indexOf('/') >= 0;
}
protected static boolean isAList(String token) {
return token != null && token.indexOf(',') >= 0;
}
protected static boolean isAll(String token) {
return token != null && token.length() == 1 && (token.charAt(0) == '*' || token.charAt(0) == '?');
}
protected static int getDenominator(final String token) {
int result = 0;
int index = token.indexOf('/');
String str = token.substring(index + 1);
result = Integer.parseInt(str);
return result;
}
protected static String getNumerator(final String token) {
int index = token.indexOf('/');
String str = token.substring(0, index);
return str;
}
static List buildCronEntries(List tokens) {
List result = new ArrayList();
CronEntry minutes = new CronEntry("Minutes", tokens.get(MINUTES), 0, 60);
minutes.currentWhen = calculateValues(minutes);
result.add(minutes);
CronEntry hours = new CronEntry("Hours", tokens.get(HOURS), 0, 24);
hours.currentWhen = calculateValues(hours);
result.add(hours);
CronEntry dayOfMonth = new CronEntry("DayOfMonth", tokens.get(DAY_OF_MONTH), 1, 32);
dayOfMonth.currentWhen = calculateValues(dayOfMonth);
result.add(dayOfMonth);
CronEntry month = new CronEntry("Month", tokens.get(MONTH), 1, 12);
month.currentWhen = calculateValues(month);
result.add(month);
CronEntry dayOfWeek = new CronEntry("DayOfWeek", tokens.get(DAY_OF_WEEK), 0, 6);
dayOfWeek.currentWhen = calculateValues(dayOfWeek);
result.add(dayOfWeek);
return result;
}
static class CronEntry {
final String name;
final String token;
final int start;
final int end;
List currentWhen;
CronEntry(String name, String token, int start, int end) {
this.name = name;
this.token = token;
this.start = start;
this.end = end;
}
@Override
public String toString() {
return this.name + ":" + token;
}
}
}
