70 lines
2.6 KiB
Java
70 lines
2.6 KiB
Java
package com.scylladb.jmx.metrics;
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import static com.scylladb.jmx.metrics.RegistrationMode.Remove;
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import static com.scylladb.jmx.metrics.RegistrationMode.Wait;
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import static java.util.EnumSet.allOf;
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import static java.util.EnumSet.of;
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import java.net.UnknownHostException;
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import java.util.EnumSet;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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import javax.management.OperationsException;
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import com.scylladb.jmx.api.APIClient;
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import com.sun.jmx.mbeanserver.JmxMBeanServer;
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/**
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* Helper type to do optional locking for registration. Allows for
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* per-bind-point locks and registration, instead of per-type or per-instance
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* locks which may be misguiding, since for example one instance can be bound to
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* many MBeanServers etc.
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*
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* Also allows for polled checks, i.e. try-lock and either wait or skip. Wait,
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* because we probably should not repeat things hidden by this type too often,
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* and skip because for example a periodic task checking can just skip if a
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* user-initiated registration check is being done.
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*
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* @author calle
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*
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*/
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@SuppressWarnings("restriction")
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public abstract class RegistrationChecker {
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private final Lock lock = new ReentrantLock();
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public static final EnumSet<RegistrationMode> REMOVE_NO_WAIT = of(Remove);
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public static final EnumSet<RegistrationMode> ADD_AND_REMOVE = allOf(RegistrationMode.class);
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public final void reap(APIClient client, JmxMBeanServer server) throws OperationsException, UnknownHostException {
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check(client, server, REMOVE_NO_WAIT);
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}
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public final void check(APIClient client, JmxMBeanServer server) throws OperationsException, UnknownHostException {
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check(client, server, ADD_AND_REMOVE);
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}
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public final void check(APIClient client, JmxMBeanServer server, EnumSet<RegistrationMode> mode)
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throws OperationsException, UnknownHostException {
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if (!lock.tryLock()) {
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if (mode.contains(Wait)) {
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// someone is doing update.
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// since this is jmx, and sloppy, we'll just
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// assume that once he is done, things are
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// good enough.
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lock.lock();
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lock.unlock();
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}
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return;
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}
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try {
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doCheck(client, server, mode);
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} finally {
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lock.unlock();
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}
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}
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protected abstract void doCheck(APIClient client, JmxMBeanServer server, EnumSet<RegistrationMode> mode)
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throws OperationsException, UnknownHostException;
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}
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