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Posted to oak-commits@jackrabbit.apache.org by th...@apache.org on 2012/09/19 12:39:03 UTC
svn commit: r1387516 - in /jackrabbit/oak/trunk/oak-jcr/src:
main/java/org/apache/jackrabbit/oak/jcr/query/
test/java/org/apache/jackrabbit/oak/jcr/query/
Author: thomasm
Date: Wed Sep 19 10:39:03 2012
New Revision: 1387516
URL: http://svn.apache.org/viewvc?rev=1387516&view=rev
Log:
OAK-300 Query: QueryResult.getRows().getSize()
Added:
jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIterator.java
jackrabbit/oak/trunk/oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIteratorTest.java
Modified:
jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/QueryResultImpl.java
Added: jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIterator.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIterator.java?rev=1387516&view=auto
==============================================================================
--- jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIterator.java (added)
+++ jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIterator.java Wed Sep 19 10:39:03 2012
@@ -0,0 +1,132 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.jackrabbit.oak.jcr.query;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * An iterator that pre-fetches a number of items in order to calculate the size
+ * of the result if possible. This iterator loads at least a number of items,
+ * and then tries to load some more items until the timeout is reached or the
+ * maximum number of entries are read.
+ * <p>
+ * Prefeching is only done when size() is called.
+ *
+ * @param <K> the iterator data type
+ */
+public class PrefetchIterator<K> implements Iterator<K> {
+
+ private final Iterator<K> it;
+ private final long minPrefetch, timeout, maxPrefetch;
+ private boolean prefetchDone;
+ private Iterator<K> prefetchIterator;
+ private long size, position;
+
+ /**
+ * Create a new iterator.
+ *
+ * @param it the base iterator
+ * @param min the minimum number of items to pre-fetch
+ * @param timeout the maximum time to pre-fetch in milliseconds
+ * @param max the maximum number of items to pre-fetch
+ * @param size the size (prefetching is only required if -1)
+ */
+ PrefetchIterator(Iterator<K> it, long min, long timeout, long max, long size) {
+ this.it = it;
+ this.minPrefetch = min;
+ this.timeout = timeout;
+ this.maxPrefetch = max;
+ this.size = size;
+ }
+
+ @Override
+ public boolean hasNext() {
+ if (prefetchIterator != null) {
+ if (prefetchIterator.hasNext()) {
+ return true;
+ }
+ prefetchIterator = null;
+ }
+ boolean result = it.hasNext();
+ if (!result) {
+ size = position;
+ }
+ return result;
+ }
+
+ @Override
+ public K next() {
+ if (!hasNext()) {
+ throw new NoSuchElementException();
+ }
+ if (prefetchIterator != null) {
+ return prefetchIterator.next();
+ }
+ position++;
+ return it.next();
+ }
+
+ @Override
+ public void remove() {
+ throw new UnsupportedOperationException();
+ }
+
+ /**
+ * Get the size if known. This call might pre-fetch data. The returned value
+ * is unknown if the actual size is larger than the number of pre-fetched
+ * elements, unless the end of the iterator has been reached already.
+ *
+ * @return the size, or -1 if unknown
+ */
+ public long size() {
+ if (size != -1 || prefetchDone || position > maxPrefetch) {
+ return size;
+ }
+ prefetchDone = true;
+ ArrayList<K> list = new ArrayList<K>();
+ long end;
+ if (timeout <= 0) {
+ end = 0;
+ } else {
+ long nanos = System.nanoTime();
+ end = nanos + timeout * 1000 * 1000;
+ }
+ while (position <= maxPrefetch) {
+ if (position > minPrefetch) {
+ if (end == 0 || System.nanoTime() > end) {
+ break;
+ }
+ }
+ if (!it.hasNext()) {
+ size = position;
+ break;
+ }
+ position++;
+ list.add(it.next());
+ }
+ if (list.size() > 0) {
+ prefetchIterator = list.iterator();
+ position -= list.size();
+ }
+ return size;
+ }
+
+}
Modified: jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/QueryResultImpl.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/QueryResultImpl.java?rev=1387516&r1=1387515&r2=1387516&view=diff
==============================================================================
--- jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/QueryResultImpl.java (original)
+++ jackrabbit/oak/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/query/QueryResultImpl.java Wed Sep 19 10:39:03 2012
@@ -42,6 +42,21 @@ import org.apache.jackrabbit.oak.jcr.Ses
* The implementation of the corresponding JCR interface.
*/
public class QueryResultImpl implements QueryResult {
+
+ /**
+ * The minimum number of rows / nodes to pre-fetch.
+ */
+ private static final int PREFETCH_MIN = 20;
+
+ /**
+ * The maximum number of rows / nodes to pre-fetch.
+ */
+ private static final int PREFETCH_MAX = 100;
+
+ /**
+ * The maximum number of milliseconds to prefetch rows / nodes.
+ */
+ private static final int PREFETCH_TIMEOUT = 100;
final SessionDelegate sessionDelegate;
final Result result;
@@ -124,9 +139,14 @@ public class QueryResultImpl implements
}
};
- return new RowIteratorAdapter(rowIterator) {
+ final PrefetchIterator<RowImpl> prefIt = new PrefetchIterator<RowImpl>(
+ rowIterator,
+ PREFETCH_MIN, PREFETCH_TIMEOUT, PREFETCH_MAX,
+ result.getSize());
+ return new RowIteratorAdapter(prefIt) {
+ @Override
public long getSize() {
- return result.getSize();
+ return prefIt.size();
}
};
}
@@ -195,7 +215,16 @@ public class QueryResultImpl implements
}
};
- return new NodeIteratorAdapter(nodeIterator, result.getSize());
+ final PrefetchIterator<NodeImpl> prefIt = new PrefetchIterator<NodeImpl>(
+ nodeIterator,
+ PREFETCH_MIN, PREFETCH_TIMEOUT, PREFETCH_MAX,
+ result.getSize());
+ return new NodeIteratorAdapter(prefIt) {
+ @Override
+ public long getSize() {
+ return prefIt.size();
+ }
+ };
}
Value createValue(CoreValue value) {
Added: jackrabbit/oak/trunk/oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIteratorTest.java
URL: http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIteratorTest.java?rev=1387516&view=auto
==============================================================================
--- jackrabbit/oak/trunk/oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIteratorTest.java (added)
+++ jackrabbit/oak/trunk/oak-jcr/src/test/java/org/apache/jackrabbit/oak/jcr/query/PrefetchIteratorTest.java Wed Sep 19 10:39:03 2012
@@ -0,0 +1,168 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.jcr.query;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import org.junit.Test;
+
+/**
+ * Test the PrefetchIterator class.
+ */
+public class PrefetchIteratorTest {
+
+ @Test
+ public void testKnownSize() {
+ Iterable<Integer> s;
+ PrefetchIterator<Integer> it;
+ s = seq(0, 100);
+ it = new PrefetchIterator<Integer>(s.iterator(), 5, 0, 10, 200);
+ // reports the 'wrong' value as it was set manually
+ assertEquals(200, it.size());
+ }
+
+ @Test
+ public void testTimeout() {
+ Iterable<Integer> s;
+ PrefetchIterator<Integer> it;
+
+ // long delay (10 ms per row)
+ long timeout = 10;
+ s = seq(0, 100, 10);
+ it = new PrefetchIterator<Integer>(s.iterator(), 5, timeout, 1000, -1);
+ assertEquals(-1, it.size());
+
+ // no delay
+ s = seq(0, 100);
+ it = new PrefetchIterator<Integer>(s.iterator(), 5, timeout, 1000, -1);
+ assertEquals(100, it.size());
+ }
+
+ @Test
+ public void test() {
+ // the following is the same as:
+ // for (int size = 0; size < 100; size++)
+ for (int size : seq(0, 100)) {
+ for (int readBefore : seq(0, 30)) {
+ // every 3th time, use a timeout
+ long timeout = size % 3 == 0 ? 100 : 0;
+ Iterable<Integer> s = seq(0, size);
+ PrefetchIterator<Integer> it =
+ new PrefetchIterator<Integer>(s.iterator(), 20, timeout, 30, -1);
+ for (int x : seq(0, readBefore)) {
+ boolean hasNext = it.hasNext();
+ if (!hasNext) {
+ assertEquals(x, size);
+ break;
+ }
+ String m = "s:" + size + " b:" + readBefore + " x:" + x;
+ assertTrue(m, hasNext);
+ assertEquals(m, x, it.next().intValue());
+ }
+ String m = "s:" + size + " b:" + readBefore;
+ int max = timeout <= 0 ? 20 : 30;
+ if (size > max && readBefore <= size) {
+ assertEquals(m, -1, it.size());
+ // calling it twice must not change the result
+ assertEquals(m, -1, it.size());
+ } else {
+ assertEquals(m, size, it.size());
+ // calling it twice must not change the result
+ assertEquals(m, size, it.size());
+ }
+ for (int x : seq(readBefore, size)) {
+ m = "s:" + size + " b:" + readBefore + " x:" + x;
+ assertTrue(m, it.hasNext());
+ assertEquals(m, x, it.next().intValue());
+ }
+ assertFalse(it.hasNext());
+ try {
+ it.next();
+ fail();
+ } catch (NoSuchElementException e) {
+ // expected
+ }
+ try {
+ it.remove();
+ fail();
+ } catch (UnsupportedOperationException e) {
+ // expected
+ }
+ }
+ }
+ }
+
+ /**
+ * Create an integer sequence.
+ *
+ * @param start the first value
+ * @param limit the last value + 1
+ * @return a sequence of the values [start .. limit-1]
+ */
+ private static Iterable<Integer> seq(final int start, final int limit) {
+ return seq(start, limit, 0);
+ }
+
+ /**
+ * Create an integer sequence.
+ *
+ * @param start the first value
+ * @param limit the last value + 1
+ * @param sleep the time to wait for each element
+ * @return a sequence of the values [start .. limit-1]
+ */
+ private static Iterable<Integer> seq(final int start, final int limit, final int sleep) {
+ return new Iterable<Integer>() {
+ @Override
+ public Iterator<Integer> iterator() {
+ return new Iterator<Integer>() {
+ int x = start;
+ @Override
+ public boolean hasNext() {
+ return x < limit;
+ }
+ @Override
+ public Integer next() {
+ if (sleep > 0) {
+ try {
+ Thread.sleep(sleep);
+ } catch (InterruptedException e) {
+ // ignore
+ }
+ }
+ return x++;
+ }
+ @Override
+ public void remove() {
+ throw new UnsupportedOperationException();
+ }
+ };
+ }
+ @Override
+ public String toString() {
+ return "[" + start + ".." + (limit - 1) + "]";
+ }
+ };
+ }
+
+}