CronExpression: Search from most to least significant field
Searching for next time from least significant to most significant field can be very expensive if the next time stamp is significantly in the future. Instead match from most significant field down to least restarting the search if a match is not found for the current field.
This commit is contained in:
Nate Clark
parent
69828d01af
commit
59d3f1134c
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@ -17,7 +17,11 @@ package fc.cron;
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*
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* Note: rewritten to standard Java 8 DateTime by zemiak (c) 2016
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*/
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import java.time.*;
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import java.time.DayOfWeek;
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import java.time.Duration;
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import java.time.LocalDate;
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import java.time.YearMonth;
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import java.time.ZonedDateTime;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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@ -129,9 +133,103 @@ import java.util.regex.Pattern;
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public class CronExpression {
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enum CronFieldType {
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SECOND(0, 59, null), MINUTE(0, 59, null), HOUR(0, 23, null), DAY_OF_MONTH(1, 31, null), MONTH(1, 12,
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Arrays.asList("JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC")), DAY_OF_WEEK(1, 7,
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Arrays.asList("MON", "TUE", "WED", "THU", "FRI", "SAT", "SUN"));
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SECOND(0, 59, null) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getSecond();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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return dateTime.withSecond(value).withNano(0);
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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return dateTime.plusMinutes(1).withSecond(0).withNano(0);
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}
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},
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MINUTE(0, 59, null) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getMinute();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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return dateTime.withMinute(value).withSecond(0).withNano(0);
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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return dateTime.plusHours(1).withMinute(0).withSecond(0).withNano(0);
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}
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},
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HOUR(0, 23, null) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getHour();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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return dateTime.withHour(value).withMinute(0).withSecond(0).withNano(0);
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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return dateTime.plusDays(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
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}
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},
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DAY_OF_MONTH(1, 31, null) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getDayOfMonth();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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return dateTime.withDayOfMonth(value).withMinute(0).withSecond(0).withNano(0);
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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return dateTime.plusMonths(1).withDayOfMonth(0).withMinute(0).withSecond(0).withNano(0);
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}
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},
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MONTH(1, 12,
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Arrays.asList("JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC")) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getMonthValue();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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return dateTime.withMonth(value).withDayOfMonth(1).withMinute(0).withSecond(0).withNano(0);
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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return dateTime.plusYears(1).withMonth(1).withDayOfMonth(1).withMinute(0).withSecond(0).withNano(0);
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}
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},
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DAY_OF_WEEK(1, 7, Arrays.asList("MON", "TUE", "WED", "THU", "FRI", "SAT", "SUN")) {
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@Override
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int getValue(ZonedDateTime dateTime) {
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return dateTime.getDayOfWeek().getValue();
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}
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@Override
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ZonedDateTime setValue(ZonedDateTime dateTime, int value) {
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throw new UnsupportedOperationException();
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}
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@Override
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ZonedDateTime overflow(ZonedDateTime dateTime) {
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throw new UnsupportedOperationException();
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}
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};
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final int from, to;
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final List<String> names;
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@ -141,6 +239,27 @@ public class CronExpression {
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this.to = to;
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this.names = names;
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}
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/**
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* @param dateTime {@link ZonedDateTime} instance
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* @return The field time or date value from {@code dateTime}
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*/
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abstract int getValue(ZonedDateTime dateTime);
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/**
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* @param dateTime Initial {@link ZonedDateTime} instance to use
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* @param value to set for this field in {@code dateTime}
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* @return {@link ZonedDateTime} with {@code value} set for this field and all smaller fields cleared
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*/
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abstract ZonedDateTime setValue(ZonedDateTime dateTime, int value);
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/**
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* Handle when this field overflows and the next higher field should be incremented
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*
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* @param dateTime Initial {@link ZonedDateTime} instance to use
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* @return {@link ZonedDateTime} with the next greater field incremented and all smaller fields cleared
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*/
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abstract ZonedDateTime overflow(ZonedDateTime dateTime);
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}
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private final String expr;
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@ -200,50 +319,53 @@ public class CronExpression {
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}
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public ZonedDateTime nextTimeAfter(ZonedDateTime afterTime, ZonedDateTime dateTimeBarrier) {
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ZonedDateTime nextTime = ZonedDateTime.from(afterTime).withNano(0).plusSeconds(1).withNano(0);
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;
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ZonedDateTime[] nextDateTime = { afterTime.plusSeconds(1).withNano(0) };
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while (true) { // day of week
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while (true) { // month
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while (true) { // day of month
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while (true) { // hour
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while (true) { // minute
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while (true) { // second
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if (secondField.matches(nextTime.getSecond())) {
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break;
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}
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nextTime = nextTime.plusSeconds(1).withNano(0);
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}
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if (minuteField.matches(nextTime.getMinute())) {
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break;
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}
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nextTime = nextTime.plusMinutes(1).withSecond(0).withNano(0);
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}
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if (hourField.matches(nextTime.getHour())) {
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break;
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}
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nextTime = nextTime.plusHours(1).withMinute(0).withSecond(0).withNano(0);
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}
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if (dayOfMonthField.matches(nextTime.toLocalDate())) {
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break;
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}
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nextTime = nextTime.plusDays(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
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checkIfDateTimeBarrierIsReached(nextTime, dateTimeBarrier);
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}
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if (monthField.matches(nextTime.getMonth().getValue())) {
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break;
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}
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nextTime = nextTime.plusMonths(1).withDayOfMonth(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
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checkIfDateTimeBarrierIsReached(nextTime, dateTimeBarrier);
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while (true) {
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checkIfDateTimeBarrierIsReached(nextDateTime[0], dateTimeBarrier);
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if (!monthField.nextMatch(nextDateTime)) {
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continue;
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}
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if (dayOfWeekField.matches(nextTime.toLocalDate())) {
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break;
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if (!findDay(nextDateTime, dateTimeBarrier)) {
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continue;
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}
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nextTime = nextTime.plusDays(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
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checkIfDateTimeBarrierIsReached(nextTime, dateTimeBarrier);
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if (!hourField.nextMatch(nextDateTime)) {
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continue;
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}
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if (!minuteField.nextMatch(nextDateTime)) {
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continue;
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}
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if (!secondField.nextMatch(nextDateTime)) {
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continue;
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}
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checkIfDateTimeBarrierIsReached(nextDateTime[0], dateTimeBarrier);
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return nextDateTime[0];
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}
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}
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return nextTime;
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/**
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* Find the next match for the day field.
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* <p>
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* This is handled different than all other fields because there are two ways to describe the day and it is easier
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* to handle them together in the same method.
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*
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* @param dateTime Initial {@link ZonedDateTime} instance to start from
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* @param dateTimeBarrier At which point stop searching for next execution time
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* @return {@code true} if a match was found for this field or {@code false} if the field overflowed
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* @see {@link SimpleField#nextMatch(ZonedDateTime[])}
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*/
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private boolean findDay(ZonedDateTime[] dateTime, ZonedDateTime dateTimeBarrier) {
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int month = dateTime[0].getMonthValue();
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while (!(dayOfMonthField.matches(dateTime[0].toLocalDate())
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&& dayOfWeekField.matches(dateTime[0].toLocalDate()))) {
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dateTime[0] = dateTime[0].plusDays(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
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if (dateTime[0].getMonthValue() != month) {
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return false;
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}
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}
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return true;
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}
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private static void checkIfDateTimeBarrierIsReached(ZonedDateTime nextTime, ZonedDateTime dateTimeBarrier) {
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@ -373,6 +495,23 @@ public class CronExpression {
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}
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return false;
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}
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protected int nextMatch(int val, FieldPart part) {
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if (val > part.to) {
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return -1;
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}
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int nextPotential = Math.max(val, part.from);
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if (part.increment == 1 || nextPotential == part.from) {
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return nextPotential;
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}
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int remainder = ((nextPotential - part.from) % part.increment);
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if (remainder != 0) {
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nextPotential += part.increment - remainder;
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}
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return nextPotential <= part.to ? nextPotential : -1;
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}
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}
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static class SimpleField extends BasicField {
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@ -390,6 +529,30 @@ public class CronExpression {
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}
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return false;
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}
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/**
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* Find the next match for this field. If a match cannot be found force an overflow and increase the next
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* greatest field.
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*
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* @param dateTime {@link ZonedDateTime} array so the reference can be modified
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* @return {@code true} if a match was found for this field or {@code false} if the field overflowed
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*/
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protected boolean nextMatch(ZonedDateTime[] dateTime) {
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int value = fieldType.getValue(dateTime[0]);
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for (FieldPart part : parts) {
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int nextMatch = nextMatch(value, part);
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if (nextMatch > -1) {
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if (nextMatch != value) {
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dateTime[0] = fieldType.setValue(dateTime[0], nextMatch);
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}
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return true;
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}
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}
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dateTime[0] = fieldType.overflow(dateTime[0]);
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return false;
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}
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}
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static class DayOfWeekField extends BasicField {
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