implemented merge sorting of items from multiple chunks

Author: aymane-harmaz

application/org.openjdk.jmc.flightrecorder.ui/src/main/java/org/openjdk/jmc/flightrecorder/ui/common/DataPageToolkit.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
  * 
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -98,6 +98,7 @@
 import org.eclipse.ui.forms.widgets.Form;
 import org.eclipse.ui.forms.widgets.FormText;
 import org.eclipse.ui.forms.widgets.FormToolkit;
+import org.openjdk.jmc.common.collection.IteratorToolkit;
 import org.openjdk.jmc.common.item.IAggregator;
 import org.openjdk.jmc.common.item.IAttribute;
 import org.openjdk.jmc.common.item.ICanonicalAccessorFactory;
@@ -643,11 +644,15 @@ public static IXDataRenderer buildSpanRenderer(IItemCollection pathItems, IColor
 	public static boolean addEndTimeLines(
 		XYDataRenderer renderer, IItemCollection items, boolean fill, Stream<IAttribute<IQuantity>> yAttributes) {
 		if (items.hasItems()) {
-			Iterator<IItemIterable> ii = items.iterator();
-			IType<IItem> type = ii.hasNext() ? ii.next().getType() : null;
-			List<IItem> allItems = new ArrayList<>();
-			items.forEach(itemStream -> itemStream.forEach(allItems::add));
-			return yAttributes.peek(a -> addEndTimeLine(renderer, allItems.iterator(), type, a, fill))
+			List<Iterator<IItem>> iterators = new ArrayList<>();
+			for (IItemIterable ii : items) {
+				iterators.add(ii.iterator());
+			}
+			IType<IItem> type = items.iterator().next().getType();
+			IMemberAccessor<IQuantity, IItem> accessor = JfrAttributes.END_TIME.getAccessor(type);
+			Comparator<IItem> comparator = Comparator.comparing(item -> accessor.getMember(item));
+			return yAttributes.peek(
+					a -> addEndTimeLine(renderer, IteratorToolkit.mergedSorting(iterators, comparator), type, a, fill))
 					.mapToLong(a -> 1L).sum() > 0;
 		}
 		return false;

application/org.openjdk.jmc.flightrecorder.ui/src/main/java/org/openjdk/jmc/flightrecorder/ui/pages/itemhandler/ItemChart.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
  * 
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -36,6 +36,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -59,12 +60,14 @@
 import org.eclipse.ui.forms.widgets.FormToolkit;
 import org.openjdk.jmc.common.IState;
 import org.openjdk.jmc.common.IWritableState;
+import org.openjdk.jmc.common.collection.IteratorToolkit;
 import org.openjdk.jmc.common.item.Aggregators;
 import org.openjdk.jmc.common.item.IAggregator;
 import org.openjdk.jmc.common.item.IAttribute;
 import org.openjdk.jmc.common.item.IItem;
 import org.openjdk.jmc.common.item.IItemCollection;
 import org.openjdk.jmc.common.item.IItemIterable;
+import org.openjdk.jmc.common.item.IMemberAccessor;
 import org.openjdk.jmc.common.item.IType;
 import org.openjdk.jmc.common.item.ItemFilters;
 import org.openjdk.jmc.common.unit.ContentType;
@@ -545,13 +548,17 @@ private Collection<ItemRow> updateLineChart(IItemCollection itemsToChart) {
 							IItemCollection itemsWithAttributeSomeType = itemsToChart
 									.apply(ItemFilters.hasAttribute(attribute));
 							if (itemsWithAttributeSomeType.hasItems()) {
-								Iterator<IItemIterable> iterator = itemsWithAttributeSomeType.iterator();
-								IType<IItem> type = iterator.hasNext() ? iterator.next().getType() : null;
-								List<IItem> allItems = new ArrayList<>();
-								itemsWithAttributeSomeType.forEach(itemStream -> itemStream.forEach(allItems::add));
+								List<Iterator<IItem>> iterators = new ArrayList<>();
+								for (IItemIterable ii : itemsWithAttributeSomeType) {
+									iterators.add(ii.iterator());
+								}
+								IType<IItem> type = itemsWithAttributeSomeType.iterator().next().getType();
+								IMemberAccessor<IQuantity, IItem> accessor = JfrAttributes.END_TIME.getAccessor(type);
+								Comparator<IItem> comparator = Comparator.comparing(item -> accessor.getMember(item));
 								@SuppressWarnings("unchecked")
 								IAttribute<IQuantity> qAttribute = (IAttribute<IQuantity>) attribute;
-								DataPageToolkit.addEndTimeLine(xyRenderer, allItems.iterator(), type, qAttribute, fill);
+								DataPageToolkit.addEndTimeLine(xyRenderer,
+										IteratorToolkit.mergedSorting(iterators, comparator), type, qAttribute, fill);
 							}
 						}
 					}

core/org.openjdk.jmc.common/src/main/java/org/openjdk/jmc/common/collection/IteratorToolkit.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
  *
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -33,9 +33,13 @@
 package org.openjdk.jmc.common.collection;
 
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 import java.util.NoSuchElementException;
+import java.util.PriorityQueue;
+import java.util.Queue;
 import java.util.function.Predicate;
 
 /**
@@ -106,6 +110,41 @@ protected T findNext() {
 		};
 	}
 
+	/**
+	 * Wrap an iterator in a new iterator that merges values from sorted iterators.
+	 *
+	 * @param <T>
+	 *            input iterator type
+	 * @param iterators
+	 *            input iterators
+	 * @param comparator
+	 *            ordering rule function
+	 * @return a new iterator that contains sorted elements
+	 */
+	public static <T> Iterator<T> mergedSorting(
+		final Collection<? extends Iterator<T>> iterators, final Comparator<T> comparator) {
+		final Queue<PeekingIterator<T>> priorityQueue = new PriorityQueue<>(
+				Comparator.comparing(PeekingIterator::peek, comparator));
+		for (Iterator<T> iterator : iterators) {
+			if (iterator.hasNext()) {
+				priorityQueue.add(new PeekingIterator<>(iterator));
+			}
+		}
+
+		return new AbstractIterator<T>() {
+			@Override
+			protected T findNext() {
+				if (priorityQueue.isEmpty())
+					return NO_MORE_ELEMENTS;
+				PeekingIterator<T> minPeekingIterator = priorityQueue.poll();
+				T result = minPeekingIterator.next();
+				if (minPeekingIterator.hasNext())
+					priorityQueue.add(minPeekingIterator);
+				return result;
+			}
+		};
+	}
+
 	/**
 	 * Iterator that iterates over an array. Hopefully faster than Arrays.asList(...).iterator()
 	 * since there are no concurrency checks.

core/org.openjdk.jmc.common/src/main/java/org/openjdk/jmc/common/collection/PeekingIterator.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2018, 2026 Oracle and/or its affiliates. All rights reserved.
+ * 
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The contents of this file are subject to the terms of either the Universal Permissive License
+ * v 1.0 as shown at https://oss.oracle.com/licenses/upl
+ *
+ * or the following license:
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
+ * and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other materials provided with
+ * the distribution.
+ * 
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
+ * endorse or promote products derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.openjdk.jmc.common.collection;
+
+import java.util.Iterator;
+
+/**
+ * Iterator wrapper that allows peeking at the next element.
+ *
+ * @param <T>
+ *            the type of elements returned by the iterator
+ */
+public class PeekingIterator<T> implements Iterator<T> {
+	private final Iterator<T> sourceIterator;
+	private T peekedElement;
+	private boolean hasPeeked;
+
+	public PeekingIterator(Iterator<T> sourceIterator) {
+		this.sourceIterator = sourceIterator;
+	}
+
+	public T peek() {
+		if (!this.hasPeeked) {
+			this.hasPeeked = true;
+			this.peekedElement = this.sourceIterator.next();
+		}
+		return this.peekedElement;
+	}
+
+	@Override
+	public T next() {
+		if (!this.hasPeeked) {
+			return this.sourceIterator.next();
+		}
+		this.hasPeeked = false;
+		T result = this.peekedElement;
+		this.peekedElement = null;
+		return result;
+	}
+
+	@Override
+	public boolean hasNext() {
+		return this.hasPeeked || this.sourceIterator.hasNext();
+	}
+}