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HBASE-15791 Improve javadoc around ScheduledChore

This commit is contained in:
Jonathan M Hsieh 2016-05-07 15:33:20 -07:00
parent 05378cbf69
commit 541d1da5fe
1 changed files with 25 additions and 12 deletions
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37
hbase-common/src/main/java/org/apache/hadoop/hbase/ScheduledChore.java
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@ -55,9 +55,9 @@ public abstract class ScheduledChore implements Runnable {
/**
* Scheduling parameters. Used by ChoreService when scheduling the chore to run periodically
*/
private final int period;
private final int period; // in TimeUnit units
private final TimeUnit timeUnit;
private final long initialDelay;
private final long initialDelay; // in TimeUnit units
/**
* Interface to the ChoreService that this ScheduledChore is scheduled with. null if the chore is
@ -68,8 +68,8 @@ public abstract class ScheduledChore implements Runnable {
/**
* Variables that encapsulate the meaningful state information
*/
private long timeOfLastRun = -1;
private long timeOfThisRun = -1;
private long timeOfLastRun = -1; // system time millis
private long timeOfThisRun = -1; // system time millis
private boolean initialChoreComplete = false;
/**
@ -127,7 +127,7 @@ public abstract class ScheduledChore implements Runnable {
/**
* @param name Name assigned to Chore. Useful for identification amongst chores of the same type
* @param stopper When {@link Stoppable#isStopped()} is true, this chore will cancel and cleanup
* @param period Period with which this Chore repeats execution when scheduled.
* @param period Period in millis with which this Chore repeats execution when scheduled.
*/
public ScheduledChore(final String name, Stoppable stopper, final int period) {
this(name, stopper, period, DEFAULT_INITIAL_DELAY);
@ -136,7 +136,7 @@ public abstract class ScheduledChore implements Runnable {
/**
* @param name Name assigned to Chore. Useful for identification amongst chores of the same type
* @param stopper When {@link Stoppable#isStopped()} is true, this chore will cancel and cleanup
* @param period Period with which this Chore repeats execution when scheduled.
* @param period Period in millis with which this Chore repeats execution when scheduled.
* @param initialDelay Delay before this Chore begins to execute once it has been scheduled. A
* value of 0 means the chore will begin to execute immediately. Negative delays are
* invalid and will be corrected to a value of 0.
@ -149,10 +149,10 @@ public abstract class ScheduledChore implements Runnable {
/**
* @param name Name assigned to Chore. Useful for identification amongst chores of the same type
* @param stopper When {@link Stoppable#isStopped()} is true, this chore will cancel and cleanup
* @param period Period with which this Chore repeats execution when scheduled.
* @param initialDelay Delay before this Chore begins to execute once it has been scheduled. A
* value of 0 means the chore will begin to execute immediately. Negative delays are
* invalid and will be corrected to a value of 0.
* @param period Period in Timeunit unit with which this Chore repeats execution when scheduled.
* @param initialDelay Delay in Timeunit unit before this Chore begins to execute once it has been
* scheduled. A value of 0 means the chore will begin to execute immediately. Negative
* delays are invalid and will be corrected to a value of 0.
* @param unit The unit that is used to measure period and initialDelay
*/
public ScheduledChore(final String name, Stoppable stopper, final int period,
@ -213,8 +213,8 @@ public abstract class ScheduledChore implements Runnable {
}
/**
* @return How long has it been since this chore last run. Useful for checking if the chore has
* missed its scheduled start time by too large of a margin
* @return How long in millis has it been since this chore last run. Useful for checking if the
* chore has missed its scheduled start time by too large of a margin
*/
synchronized long getTimeBetweenRuns() {
return timeOfThisRun - timeOfLastRun;
@ -228,11 +228,18 @@ public abstract class ScheduledChore implements Runnable {
&& getTimeBetweenRuns() > getMaximumAllowedTimeBetweenRuns();
}
/**
* @return max allowed time in millis between runs.
*/
private double getMaximumAllowedTimeBetweenRuns() {
// Threshold used to determine if the Chore's current run started too late
return 1.5 * timeUnit.toMillis(period);
}
/**
* @param time in system millis
* @return true if time is earlier or equal to current milli time
*/
private synchronized boolean isValidTime(final long time) {
return time > 0 && time <= System.currentTimeMillis();
}
@ -276,10 +283,16 @@ public abstract class ScheduledChore implements Runnable {
return stopper;
}
/**
* @return period to execute chore in getTimeUnit() units
*/
public int getPeriod() {
return period;
}
/**
* @return initial delay before executing chore in getTimeUnit() units
*/
public long getInitialDelay() {
return initialDelay;
}