Package org.apache.druid.java.util.common.concurrent

Class ScheduledExecutors

java.lang.Object

org.apache.druid.java.util.common.concurrent.ScheduledExecutors

public class ScheduledExecutors
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	ScheduledExecutors.Signal

Constructor Summary

Constructors

Constructor	Description
ScheduledExecutors()

Method Summary

Modifier and Type	Method	Description
static ScheduledExecutorFactory	createFactory(Lifecycle lifecycle)
static ScheduledExecutorService	emittingDelayMetric(ScheduledExecutorService exec, ServiceEmitter emitter, String metricName, Map<String,Object> metricDimensions)	Wraps a ScheduledExecutorService to emit a metric each time a task from ScheduledExecutorService.schedule(java.lang.Runnable, long, java.util.concurrent.TimeUnit) runs.
static ScheduledExecutorService	fixed(int corePoolSize, String nameFormat)	Creates a new ScheduledExecutorService with a minimum number of threads.
static ScheduledThreadPoolExecutor	fixedWithKeepAliveTime(int corePoolSize, String nameFormat, long keepAliveTimeInMillis)	Creates a new ScheduledExecutorService with a minimum number of threads along with a keep-alive time for idle non-core threads.
static void	scheduleAtFixedRate(ScheduledExecutorService exec, org.joda.time.Duration rate, Callable<ScheduledExecutors.Signal> callable)
static void	scheduleAtFixedRate(ScheduledExecutorService exec, org.joda.time.Duration initialDelay, org.joda.time.Duration period, Runnable runnable)	Schedules a runnable to execute repeatedly at a fixed rate.
static void	scheduleAtFixedRate(ScheduledExecutorService exec, org.joda.time.Duration initialDelay, org.joda.time.Duration rate, Callable<ScheduledExecutors.Signal> callable)
static void	scheduleWithFixedDelay(ScheduledExecutorService exec, org.joda.time.Duration initialDelay, org.joda.time.Duration delay, Runnable runnable)	Run runnable repeatedly with the given delay between calls, after the given initial delay.
static void	scheduleWithFixedDelay(ScheduledExecutorService exec, org.joda.time.Duration initialDelay, org.joda.time.Duration delay, Callable<ScheduledExecutors.Signal> callable)	Run callable repeatedly with the given delay between calls, until it returns Signal.STOP or the executor is shut down.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ScheduledExecutors

public ScheduledExecutors()

Method Details

scheduleWithFixedDelay

public static void scheduleWithFixedDelay(ScheduledExecutorService exec,
 org.joda.time.Duration initialDelay,
 org.joda.time.Duration delay,
 Runnable runnable)

Run runnable repeatedly with the given delay between calls, after the given initial delay. Exceptions are caught and logged as errors.

scheduleWithFixedDelay

public static void scheduleWithFixedDelay(ScheduledExecutorService exec,
 org.joda.time.Duration initialDelay,
 org.joda.time.Duration delay,
 Callable<ScheduledExecutors.Signal> callable)

Run callable repeatedly with the given delay between calls, until it returns Signal.STOP or the executor is shut down. Exceptions are caught and logged as errors, and do not prevent subsequent executions.

scheduleAtFixedRate

public static void scheduleAtFixedRate(ScheduledExecutorService exec,
 org.joda.time.Duration initialDelay,
 org.joda.time.Duration period,
 Runnable runnable)

Schedules a runnable to execute repeatedly at a fixed rate. The first execution occurs after the initial delay, and subsequent executions are scheduled at fixed intervals measured from the start of each execution.

This differs from scheduleWithFixedDelay(java.util.concurrent.ScheduledExecutorService, org.joda.time.Duration, org.joda.time.Duration, java.lang.Runnable) in that the period is measured from the start of each execution rather than from the completion. If an execution takes longer than the period, the next execution will begin immediately after the current one completes.

This also differs from ScheduledExecutorService.scheduleAtFixedRate(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit) in that it prevents task pileup: only one future execution is scheduled at a time rather than scheduling all future executions upfront. This prevents a backlog of pending tasks from building up if the executor is delayed or tasks run slowly.

Exceptions thrown by the task are caught and logged as errors, and do not prevent subsequent executions. Scheduling also stops if the executor is shut down.

Parameters:

exec - the ScheduledExecutorService to use for scheduling

initialDelay - the duration to wait before the first execution

period - the target duration between the start of consecutive executions

runnable - the task to execute repeatedly

scheduleAtFixedRate

public static void scheduleAtFixedRate(ScheduledExecutorService exec,
 org.joda.time.Duration rate,
 Callable<ScheduledExecutors.Signal> callable)

scheduleAtFixedRate

public static void scheduleAtFixedRate(ScheduledExecutorService exec,
 org.joda.time.Duration initialDelay,
 org.joda.time.Duration rate,
 Callable<ScheduledExecutors.Signal> callable)

emittingDelayMetric

public static ScheduledExecutorService emittingDelayMetric(ScheduledExecutorService exec,
 ServiceEmitter emitter,
 String metricName,
 Map<String,Object> metricDimensions)

Wraps a ScheduledExecutorService to emit a metric each time a task from ScheduledExecutorService.schedule(java.lang.Runnable, long, java.util.concurrent.TimeUnit) runs. The metric value is the scheduling lag: the difference between the actual delay and the intended delay, in milliseconds, floored at zero.

Parameters:

exec - the executor to wrap

emitter - the emitter to emit metrics to

metricName - the name of the metric to emit

metricDimensions - dimensions to include with the metric

createFactory

public static ScheduledExecutorFactory createFactory(Lifecycle lifecycle)

fixed

public static ScheduledExecutorService fixed(int corePoolSize,
 String nameFormat)

Creates a new ScheduledExecutorService with a minimum number of threads.

Parameters:

corePoolSize - the minimum number of threads in the pool

nameFormat - the naming format for threads created by the pool

Returns:

a new ScheduledExecutorService with the specified configuration

fixedWithKeepAliveTime

public static ScheduledThreadPoolExecutor fixedWithKeepAliveTime(int corePoolSize,
 String nameFormat,
 long keepAliveTimeInMillis)

Creates a new ScheduledExecutorService with a minimum number of threads along with a keep-alive time for idle non-core threads.