Author: desruisseaux
Date: Wed Jan 9 07:55:21 2013
New Revision: 1430721
URL: http://svn.apache.org/viewvc?rev=1430721&view=rev
Log:
Implemented removal of (un)marshaller after a timeout.
Modified:
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/MarshallerPool.java
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/Pooled.java
Modified:
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/MarshallerPool.java
URL:
http://svn.apache.org/viewvc/sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/MarshallerPool.java?rev=1430721&r1=1430720&r2=1430721&view=diff
==============================================================================
---
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/MarshallerPool.java
(original)
+++
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/MarshallerPool.java
Wed Jan 9 07:55:21 2013
@@ -18,14 +18,17 @@ package org.apache.sis.xml;
import java.util.Map;
import java.util.Deque;
-import java.util.LinkedList;
import java.util.Collections;
+import java.util.concurrent.ConcurrentLinkedDeque;
+import java.util.concurrent.atomic.AtomicBoolean;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import net.jcip.annotations.ThreadSafe;
import org.apache.sis.util.logging.Logging;
+import org.apache.sis.internal.util.DelayedExecutor;
+import org.apache.sis.internal.util.DelayedRunnable;
import org.apache.sis.internal.jaxb.AdapterReplacement;
@@ -51,15 +54,15 @@ import org.apache.sis.internal.jaxb.Adap
* @module
*
* @see XML
- *
- * @todo Need a timeout for disposing marshallers that have been unused for a
while.
*/
@ThreadSafe
public class MarshallerPool {
/**
- * Maximal amount of marshallers and unmarshallers to keep.
+ * Amount of nanoseconds to wait before to remove unused (un)marshallers.
+ * This is a very approximative value: actual timeout will not be shorter,
+ * but may be twice longer.
*/
- private static final int CAPACITY = 16;
+ private static final long TIMEOUT = 15000000000L; // 15 seconds.
/**
* The key to be used in the map given to the constructors for specifying
the root namespace.
@@ -85,16 +88,38 @@ public class MarshallerPool {
private final Object mapper;
/**
- * The pool of marshaller. This pool is initially empty
- * and will be filled with elements as needed.
+ * The pool of marshaller. This pool is initially empty and will be filled
with elements as needed.
+ * Marshallers (if any) shall be fetched using the {@link Deque#poll()}
method and, after use,
+ * given back to the pool using the {@link Deque#push(Object)} method.
+ *
+ * <p>This queue must be a thread-safe implementation, since it will not
be invoked in
+ * synchronized block.</p>
+ *
+ * @see #acquireMarshaller()
+ * @see #release(Marshaller)
+ */
+ private final Deque<Marshaller> marshallers;
+
+ /**
+ * The pool of unmarshaller. This pool is initially empty and will be
filled with elements as needed.
+ * Unmarshallers (if any) shall be fetched using the {@link Deque#poll()}
method and, after use,
+ * given back to the pool using the {@link Deque#push(Object)} method.
+ *
+ * <p>This queue must be a thread-safe implementation, since it will not
be invoked in
+ * synchronized block.</p>
+ *
+ * @see #acquireUnmarshaller()
+ * @see #release(Unmarshaller)
*/
- private final Deque<Marshaller> marshallers = new LinkedList<>();
+ private final Deque<Unmarshaller> unmarshallers;
/**
- * The pool of unmarshaller. This pool is initially empty
- * and will be filled with elements as needed.
+ * {@code true} if a task has been scheduled for removing expired
(un)marshallers,
+ * or {@code false} if no removal task is currently scheduled.
+ *
+ * @see #scheduleRemoval()
*/
- private final Deque<Unmarshaller> unmarshallers = new LinkedList<>();
+ private final AtomicBoolean isRemovalScheduled;
/**
* Creates a new factory for the given class to be bound, with a default
empty namespace.
@@ -120,11 +145,14 @@ public class MarshallerPool {
/**
* Creates a new factory for the given packages, with a default empty
namespace.
- * The separator character for the packages is the colon.
+ * The separator character for the packages is the colon. Example:
*
- * @param packages The packages in which JAXB will search for
annotated classes to be bound,
- * for example {@code
"org.apache.sis.metadata.iso:org.apache.sis.metadata.iso.citation"}.
- * @throws JAXBException If the JAXB context can not be created.
+ * {@preformat text
+ * "org.apache.sis.metadata.iso:org.apache.sis.metadata.iso.citation"
+ * }
+ *
+ * @param packages The colon-separated list of packages in which
JAXB will search for annotated classes.
+ * @throws JAXBException If the JAXB context can not be created.
*/
public MarshallerPool(final String packages) throws JAXBException {
this(Collections.<String,String>emptyMap(), packages);
@@ -136,8 +164,7 @@ public class MarshallerPool {
* in this class like {@link #ROOT_NAMESPACE_KEY}.
*
* @param properties The set of properties to be given to the pool.
- * @param packages The packages in which JAXB will search for
annotated classes to be bound,
- * for example {@code
"org.apache.sis.metadata.iso:org.apache.sis.metadata.iso.citation"}.
+ * @param packages The colon-separated list of packages in which
JAXB will search for annotated classes.
* @throws JAXBException If the JAXB context can not be created.
*/
public MarshallerPool(final Map<String,String> properties, final String
packages) throws JAXBException {
@@ -173,50 +200,112 @@ public class MarshallerPool {
}
/*
* Instantiates the OGCNamespacePrefixMapper appropriate for the
implementation
- * we just detected.
+ * we just detected. Note that we may get NoClassDefFoundError instead
than the
+ * usual ClassNotFoundException if the class was found but its parent
class has
+ * not been found.
*/
try {
mapper =
Class.forName(type).getConstructor(String.class).newInstance(rootNamespace);
} catch (ReflectiveOperationException | NoClassDefFoundError
exception) {
- // The NoClassDefFoundError is because of our trick using
"geotk-provided".
throw new JAXBException("Unsupported JAXB implementation.",
exception);
}
- }
-
- /**
- * Returns the marshaller or unmarshaller to use from the given queue.
- * If the queue is empty, returns {@code null}.
- */
- private static <T> T acquire(final Deque<T> queue) {
- synchronized (queue) {
- return queue.pollLast();
- }
+ marshallers = new ConcurrentLinkedDeque<>();
+ unmarshallers = new ConcurrentLinkedDeque<>();
+ isRemovalScheduled = new AtomicBoolean();
}
/**
* Marks the given marshaller or unmarshaller available for further reuse.
+ * This method:
+ *
+ * <ul>
+ * <li>{@link Pooled#reset() Resets} the (un)marshaller to its initial
state.</li>
+ * <li>{@linkplain Deque#push(Object) Pushes} the (un)marshaller in the
given queue.</li>
+ * <li>Registers a delayed task for disposing expired (un)marshallers
after the timeout.</li>
+ * </ul>
*/
- private static <T> void release(final Deque<T> queue, final T marshaller) {
+ private <T> void release(final Deque<T> queue, final T marshaller) {
try {
((Pooled) marshaller).reset();
} catch (JAXBException exception) {
- // Not expected to happen because the we are supposed
+ // Not expected to happen because we are supposed
// to reset the properties to their initial values.
Logging.unexpectedException(MarshallerPool.class, "release",
exception);
return;
}
- synchronized (queue) {
- queue.addLast(marshaller);
- while (queue.size() > CAPACITY) {
- // Remove the least recently used marshallers.
- queue.removeFirst();
+ queue.push(marshaller);
+ scheduleRemoval();
+ }
+
+ /**
+ * Schedule a new task for removing expired (un)marshallers if no such
task is currently
+ * registered. If a task is already registered, then this method does
nothing. Note that
+ * this task will actually wait for a longer time than the {@link
#TIMEOUT} value before
+ * to execute, in order to increase the chances to process many
(un)marshallers at once.
+ */
+ private void scheduleRemoval() {
+ if (isRemovalScheduled.compareAndSet(false, true)) {
+ DelayedExecutor.schedule(new DelayedRunnable(System.nanoTime() +
2*TIMEOUT) {
+ @Override public void run() {
+ removeExpired();
+ }
+ });
+ }
+ }
+
+ /**
+ * Invoked from the task scheduled by {@link #scheduleRemoval()} for
removing expired
+ * (un)marshallers. If some (un)marshallers remain after execution of this
task, then
+ * this method will reschedule a new task for checking again later.
+ */
+ final void removeExpired() {
+ isRemovalScheduled.set(false);
+ final long now = System.nanoTime();
+ if (!removeExpired(marshallers, now) | // Really |, not ||
+ !removeExpired(unmarshallers, now))
+ {
+ scheduleRemoval();
+ }
+ }
+
+ /**
+ * Removes expired (un)marshallers from the given queue.
+ *
+ * @param <T> Either {@code Marshaller} or {@code Unmarshaller} type.
+ * @param queue The queue from which to remove expired (un)marshallers.
+ * @param now Current value of {@link System#nanoTime()}.
+ * @return {@code true} if the queue became empty as a result of this
method call.
+ */
+ private static <T> boolean removeExpired(final Deque<T> queue, final long
now) {
+ T next;
+ while ((next = queue.peekLast()) != null) {
+ /*
+ * The above line fetched the oldest (un)marshaller without
removing it.
+ * If the timeout is not yet elapsed, do not remove that
(un)marshaller.
+ * Since marshallers are enqueued in chronological order, the next
ones
+ * should be yet more recent, so it is not worth to continue the
search.
+ */
+ if (now - ((Pooled) next).resetTime < TIMEOUT) {
+ return false;
+ }
+ /*
+ * Now remove the (un)marshaller and check again the timeout. This
second
+ * check is because the oldest (un)marshaller may have changed
concurrently
+ * (depending on the queue implementation, which depends on the
target JDK).
+ * If such case, restore the (un)marshaller on the queue.
+ */
+ next = queue.pollLast();
+ if (now - ((Pooled) next).resetTime < TIMEOUT) {
+ queue.addLast(next);
+ return false;
}
}
+ return true;
}
/**
* Returns a JAXB marshaller from the pool. If there is no marshaller
currently available
- * in the pool, then this method will {@linkplain #createMarshaller
create} a new one.
+ * in the pool, then this method will {@linkplain #createMarshaller()
create} a new one.
*
* <p>This method shall be used as below:</p>
*
@@ -234,7 +323,7 @@ public class MarshallerPool {
* @throws JAXBException If an error occurred while creating and
configuring a marshaller.
*/
public Marshaller acquireMarshaller() throws JAXBException {
- Marshaller marshaller = acquire(marshallers);
+ Marshaller marshaller = marshallers.poll();
if (marshaller == null) {
marshaller = new PooledMarshaller(createMarshaller(), internal);
}
@@ -243,7 +332,7 @@ public class MarshallerPool {
/**
* Returns a JAXB unmarshaller from the pool. If there is no unmarshaller
currently available
- * in the pool, then this method will {@linkplain #createUnmarshaller
create} a new one.
+ * in the pool, then this method will {@linkplain #createUnmarshaller()
create} a new one.
*
* <p>This method shall be used as below:</p>
*
@@ -261,7 +350,7 @@ public class MarshallerPool {
* @throws JAXBException If an error occurred while creating and
configuring the unmarshaller.
*/
public Unmarshaller acquireUnmarshaller() throws JAXBException {
- Unmarshaller unmarshaller = acquire(unmarshallers);
+ Unmarshaller unmarshaller = unmarshallers.poll();
if (unmarshaller == null) {
unmarshaller = new PooledUnmarshaller(createUnmarshaller(),
internal);
}
Modified:
sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/Pooled.java
URL:
http://svn.apache.org/viewvc/sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/Pooled.java?rev=1430721&r1=1430720&r2=1430721&view=diff
==============================================================================
--- sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/Pooled.java
(original)
+++ sis/branches/JDK7/sis-utility/src/main/java/org/apache/sis/xml/Pooled.java
Wed Jan 9 07:55:21 2013
@@ -132,6 +132,13 @@ abstract class Pooled {
private int bitMasks;
/**
+ * The {@link System#nanoTime()} value of the last call to {@link
#reset()}.
+ * This is used for disposing (un)marshallers that have not been used for
a while,
+ * since {@code reset()} is invoked just before to push a (un)marshaller
in the pool.
+ */
+ volatile long resetTime;
+
+ /**
* Default constructor.
*
* @param internal {@code true} if the JAXB implementation is the one
bundled in JDK 6,
@@ -153,7 +160,9 @@ abstract class Pooled {
}
/**
- * Resets the (un)marshaller to its initial state.
+ * Releases resources and resets the (un)marshaller to its initial state.
+ * This method is invoked by {@link MarshallerPool} just before to push a
+ * (un)marshaller in the pool after its usage.
*
* @throws JAXBException If an error occurred while restoring a property.
*/
@@ -169,6 +178,7 @@ abstract class Pooled {
locale = null;
timezone = null;
bitMasks = initialBitMasks();
+ resetTime = System.nanoTime();
}
/**
