Package org.apache.accumulo.core.util.cleaner

Class CleanerUtil

java.lang.Object

org.apache.accumulo.core.util.cleaner.CleanerUtil

public class CleanerUtil
extends Object

This class collects all the cleaner actions executed in various parts of the code.

These actions replace the use of finalizers, which are deprecated in Java 9 and later, and should be avoided. These actions are triggered by their respective objects when those objects become phantom reachable.

In the "unclosed*" methods below, the object should have been closed (implements AutoCloseable). We could possibly consolidate these into a single method which only warns, and doesn't try to clean up. We could also delete them entirely, since it is the caller's responsibility to close AutoCloseable resources, not the object's own responsibility to detect that it wasn't closed.

Field Summary

Fields

Modifier and Type	Field	Description
static Cleaner	CLEANER

Constructor Summary

Constructors

Constructor	Description
CleanerUtil()

Method Summary

Modifier and Type	Method	Description
static Cleaner.Cleanable	batchWriterAndClientCloser(Object o, org.slf4j.Logger log, BatchWriter bw, AccumuloClient client)
static Cleaner.Cleanable	shutdownThreadPoolExecutor(ExecutorService pool, AtomicBoolean closed, org.slf4j.Logger log)
static Cleaner.Cleanable	unclosed(AutoCloseable obj, Class<?> objClass, AtomicBoolean closed, org.slf4j.Logger log, AutoCloseable closeable)	Register an action to warn about caller failing to close an AutoCloseable object.
static Cleaner.Cleanable	zooCacheClearer(Object o, ZooCache zc)

Methods inherited from class java.lang.Object

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

Field Detail

CLEANER

public static final Cleaner CLEANER

Constructor Detail

CleanerUtil

public CleanerUtil()

Method Detail

unclosed

public static Cleaner.Cleanable unclosed(AutoCloseable obj,
                                         Class<?> objClass,
                                         AtomicBoolean closed,
                                         org.slf4j.Logger log,
                                         AutoCloseable closeable)

Register an action to warn about caller failing to close an AutoCloseable object.

This task will register a generic action to:

1. check that the monitored object wasn't closed,
2. log a warning that the monitored object was not closed,
3. attempt to close a resource within the object, and
4. log an error if the resource cannot be closed for any reason

Parameters:

obj - the object to monitor for becoming phantom-reachable without having been closed

objClass - the class whose simple name will be used in the log message for o (usually an interface name, rather than the actual impl name of the object)

closed - a flag to check whether o has already been closed

log - the logger to use when emitting error/warn messages

closeable - the resource within o to close when o is cleaned; must not contain a reference to the monitoredObject or it won't become phantom-reachable and will never be cleaned

Returns:

the registered Cleaner.Cleanable from Cleaner.register(Object, Runnable)

shutdownThreadPoolExecutor

public static Cleaner.Cleanable shutdownThreadPoolExecutor(ExecutorService pool,
                                                           AtomicBoolean closed,
                                                           org.slf4j.Logger log)

batchWriterAndClientCloser

public static Cleaner.Cleanable batchWriterAndClientCloser(Object o,
                                                           org.slf4j.Logger log,
                                                           BatchWriter bw,
                                                           AccumuloClient client)

zooCacheClearer

public static Cleaner.Cleanable zooCacheClearer(Object o,
                                                ZooCache zc)