This closes #3393

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/collections/ConcurrentAppendOnlyChunkedList.java

@@ -42,8 +42,6 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
 
    private static final AtomicLongFieldUpdater<ConcurrentAppendOnlyChunkedList> LAST_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(ConcurrentAppendOnlyChunkedList.class, "lastIndex");
 
-   private static final AtomicLongFieldUpdater<ConcurrentAppendOnlyChunkedList> CACHED_LAST_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(ConcurrentAppendOnlyChunkedList.class, "cachedLastIndex");
-
    private final int chunkSize;
 
    private final int chunkMask;
@@ -58,10 +56,6 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
    //it's using a parity bit to mark the rotation state ie size === lastIndex >> 1
    private volatile long lastIndex = 0;
 
-   //cached view of lastIndex used to avoid invalidating lastIndex while being updated by the appends
-
-   private volatile long cachedLastIndex = 0;
-
    /**
     * @throws IllegalArgumentException if {@code chunkSize} is &lt;0 or not a power of 2
     */
@@ -105,17 +99,11 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       if (index < 0) {
          return null;
       }
-      //it allow to perform less cache invalidations vs lastIndex if there are bursts of appends
+      final long lastIndex = getValidLastIndex();
-      long lastIndex = cachedLastIndex;
-      if (index >= lastIndex) {
-         lastIndex = getValidLastIndex();
       //it is a element over the current size?
       if (index >= lastIndex) {
          return null;
       }
-         //publish it for others readers
-         CACHED_LAST_INDEX_UPDATER.lazySet(this, lastIndex);
-      }
       final AtomicChunk<T> buffer;
       final int offset;
       if (index >= chunkSize) {
@@ -139,20 +127,20 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       final int chunkIndex = index >> chunkSizeLog2;
       //size is never allowed to be > Integer.MAX_VALUE
       final int lastChunkIndex = (int) lastIndex >> chunkSizeLog2;
-      int chunkIndexes = chunkIndex;
+      int distance = chunkIndex;
       AtomicChunk<T> buffer = null;
       boolean forward = true;
-      int distanceFromLastChunkIndex = lastChunkIndex - chunkIndex;
+      int distanceFromLast = lastChunkIndex - chunkIndex;
       //it's worth to go backward from lastChunkIndex?
       //trying first to check against the value we already have: if it won't worth, won't make sense to load the lastBuffer
-      if (distanceFromLastChunkIndex < chunkIndex) {
+      if (distanceFromLast < distance) {
          final AtomicChunk<T> lastBuffer = this.lastBuffer;
          //lastBuffer is a potential moving, always increasing, target ie better to re-check the distance
-         distanceFromLastChunkIndex = lastBuffer.index - chunkIndex;
+         distanceFromLast = lastBuffer.index - chunkIndex;
-         if (distanceFromLastChunkIndex < chunkIndex) {
+         if (distanceFromLast < distance) {
             //we're saving some jumps ie is fine to go backward from here
             buffer = lastBuffer;
-            chunkIndexes = distanceFromLastChunkIndex;
+            distance = distanceFromLast;
             forward = false;
          }
       }
@@ -160,7 +148,7 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       if (buffer == null) {
          buffer = firstBuffer;
       }
-      for (int i = 0; i < chunkIndexes; i++) {
+      for (int i = 0; i < distance; i++) {
          //next chunk is always set if below a read lastIndex value
          //previous chunk is final and can be safely read
          buffer = forward ? buffer.next : buffer.prev;
@@ -234,21 +222,31 @@ public final class ConcurrentAppendOnlyChunkedList<T> {
       return true;
    }
 
+   public T[] toArray(IntFunction<T[]> arrayAllocator) {
+      return toArray(arrayAllocator, 0);
+   }
+
    /**
     * Returns an array containing all of the elements in this collection in proper
     * sequence (from first to last element).<br>
     * {@code arrayAllocator} will be used to instantiate the array of the correct size with the right runtime type.
     */
-   public T[] toArray(IntFunction<T[]> arrayAllocator) {
+   public T[] toArray(IntFunction<T[]> arrayAllocator, int startIndex) {
+      if (startIndex < 0) {
+         throw new ArrayIndexOutOfBoundsException("startIndex must be >= 0");
+      }
       final long lastIndex = getValidLastIndex();
       assert lastIndex <= Integer.MAX_VALUE;
       final int size = (int) lastIndex;
       final T[] elements = arrayAllocator.apply(size);
+      if (startIndex + size > elements.length) {
+         throw new ArrayIndexOutOfBoundsException();
+      }
       //fast division by a power of 2
       final int chunkSize = this.chunkSize;
       final int chunks = size > chunkSize ? size >> chunkSizeLog2 : 0;
       AtomicChunk<T> buffer = firstBuffer;
-      int elementIndex = 0;
+      int elementIndex = startIndex;
       for (int i = 0; i < chunks; i++) {
          drain(buffer, elements, elementIndex, chunkSize);
          elementIndex += chunkSize;

artemis-commons/src/test/java/org/apache/activemq/artemis/utils/collections/ConcurrentAppendOnlyChunkedListTest.java

@@ -20,13 +20,15 @@
  */
 package org.apache.activemq.artemis.utils.collections;
 
+import java.util.Arrays;
+
 import org.junit.Assert;
 import org.junit.Test;
 
 public class ConcurrentAppendOnlyChunkedListTest {
 
-   private static final int CHUNK_SIZE = 32;
+   private static final int CHUNK_SIZE = 16;
-   private static final int ELEMENTS = (CHUNK_SIZE * 3) + 1;
+   private static final int ELEMENTS = (CHUNK_SIZE * 4) + 1;
 
    private final ConcurrentAppendOnlyChunkedList<Integer> chunkedList;
 
@@ -101,7 +103,12 @@ public class ConcurrentAppendOnlyChunkedListTest {
       for (int i = 0; i < messages; i++) {
          cachedElements[i] = chunkedList.get(i);
       }
-      Assert.assertArrayEquals(cachedElements, elements);
+      Assert.assertArrayEquals(elements, cachedElements);
+      Arrays.fill(cachedElements, null);
+      for (int i = messages - 1; i >= 0; i--) {
+         cachedElements[i] = chunkedList.get(i);
+      }
+      Assert.assertArrayEquals(elements, cachedElements);
    }
 
    @Test
@@ -117,7 +124,7 @@ public class ConcurrentAppendOnlyChunkedListTest {
       for (int i = 0; i < messages; i++) {
          cachedElements[i] = chunkedList.get(i);
       }
-      Assert.assertArrayEquals(cachedElements, elements);
+      Assert.assertArrayEquals(elements, cachedElements);
    }
 
    @Test
@@ -133,6 +140,44 @@ public class ConcurrentAppendOnlyChunkedListTest {
       Assert.assertArrayEquals(elements, cachedElements);
    }
 
+   @Test
+   public void shouldToArrayWithIndexReturnElementsAccordingToAddOrder() {
+      final int messages = ELEMENTS;
+      final Integer[] elements = new Integer[messages];
+      for (int i = 0; i < messages; i++) {
+         final Integer element = i;
+         elements[i] = element;
+         chunkedList.add(element);
+      }
+      final int offset = 10;
+      final Integer[] cachedElements = chunkedList.toArray(size -> new Integer[offset + size], offset);
+      Assert.assertArrayEquals(elements, Arrays.copyOfRange(cachedElements, offset, cachedElements.length));
+      Assert.assertArrayEquals(new Integer[offset], Arrays.copyOfRange(cachedElements, 0, offset));
+   }
+
+   @Test(expected = ArrayIndexOutOfBoundsException.class)
+   public void shouldFailToArrayWithInsufficientArrayCapacity() {
+      final int messages = ELEMENTS;
+      final Integer[] elements = new Integer[messages];
+      for (int i = 0; i < messages; i++) {
+         final Integer element = i;
+         elements[i] = element;
+         chunkedList.add(element);
+      }
+      final int offset = 10;
+      chunkedList.toArray(size -> new Integer[offset + size - 1], offset);
+   }
+
+   @Test(expected = ArrayIndexOutOfBoundsException.class)
+   public void shouldFailToArrayWithNegativeStartIndex() {
+      chunkedList.toArray(Integer[]::new, -1);
+   }
+
+   @Test(expected = NullPointerException.class)
+   public void shouldFailToArrayWithNullArray() {
+      chunkedList.toArray(size -> null);
+   }
+
    @Test
    public void shouldToArrayReturnElementsAccordingToAddAllOrder() {
       final int messages = ELEMENTS;

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/BulkPageCache.java

@@ -0,0 +1,24 @@
+/*
+ * 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.activemq.artemis.core.paging.cursor;
+
+import org.apache.activemq.artemis.core.paging.PagedMessage;
+
+public interface BulkPageCache extends PageCache {
+
+    PagedMessage[] getMessages();
+}

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/LivePageCache.java

@@ -18,7 +18,7 @@ package org.apache.activemq.artemis.core.paging.cursor;
 
 import org.apache.activemq.artemis.core.paging.PagedMessage;
 
-public interface LivePageCache extends PageCache {
+public interface LivePageCache extends BulkPageCache {
 
    void addLiveMessage(PagedMessage message);
 }

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/PageCache.java

@@ -19,28 +19,19 @@ package org.apache.activemq.artemis.core.paging.cursor;
 import org.apache.activemq.artemis.core.paging.PagedMessage;
 import org.apache.activemq.artemis.utils.SoftValueLongObjectHashMap;
 
-public interface PageCache extends SoftValueLongObjectHashMap.ValueCache {
+public interface PageCache extends SoftValueLongObjectHashMap.ValueCache, AutoCloseable {
 
    long getPageId();
 
    int getNumberOfMessages();
 
-   void setMessages(PagedMessage[] messages);
-
-   PagedMessage[] getMessages();
-
-   /**
-    * @return whether this cache is still being updated
-    */
-   @Override
-   boolean isLive();
-
    /**
     * @param pagePosition page position
     * @return
     */
    PagedMessage getMessage(PagePosition pagePosition);
 
+   @Override
    void close();
 
 }

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/PageCursorProvider.java

@@ -33,7 +33,7 @@ public interface PageCursorProvider {
 
    PagedReference newReference(PagePosition pos, PagedMessage msg, PageSubscription sub);
 
-   void addPageCache(PageCache cache);
+   void addLivePageCache(LivePageCache cache);
 
    /**
     * @param queueId The cursorID should be the same as the queueId associated for persistence

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/PagePosition.java

@@ -34,8 +34,6 @@ public interface PagePosition extends Comparable<PagePosition> {
 
    void setPersistentSize(long persistentSize);
 
-   PagePosition nextMessage();
-
    PagePosition nextPage();
 
 }

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/LivePageCacheImpl.java

@@ -31,7 +31,9 @@ public final class LivePageCacheImpl implements LivePageCache {
 
    private static final int CHUNK_SIZE = 32;
 
-   private final ConcurrentAppendOnlyChunkedList<PagedMessage> messages;
+   private final PagedMessage[] initialMessages;
+
+   private final ConcurrentAppendOnlyChunkedList<PagedMessage> liveMessages;
 
    private final long pageId;
 
@@ -39,7 +41,19 @@ public final class LivePageCacheImpl implements LivePageCache {
 
    public LivePageCacheImpl(final long pageId) {
       this.pageId = pageId;
-      this.messages = new ConcurrentAppendOnlyChunkedList<>(CHUNK_SIZE);
+      this.liveMessages = new ConcurrentAppendOnlyChunkedList<>(CHUNK_SIZE);
+      this.initialMessages = null;
+   }
+
+   public LivePageCacheImpl(final long pageId, PagedMessage[] initialMessages) {
+      this.pageId = pageId;
+      this.liveMessages = new ConcurrentAppendOnlyChunkedList<>(CHUNK_SIZE);
+      this.initialMessages = initialMessages;
+   }
+
+   private int initialMessagesSize() {
+      final PagedMessage[] initialMessages = this.initialMessages;
+      return initialMessages == null ? 0 : initialMessages.length;
    }
 
    @Override
@@ -49,20 +63,21 @@ public final class LivePageCacheImpl implements LivePageCache {
 
    @Override
    public int getNumberOfMessages() {
-      return messages.size();
+      return initialMessagesSize() + liveMessages.size();
-   }
-
-   @Override
-   public void setMessages(PagedMessage[] messages) {
-      // This method shouldn't be called on liveCache, but we will provide the implementation for it anyway
-      for (PagedMessage message : messages) {
-         addLiveMessage(message);
-      }
    }
 
    @Override
    public PagedMessage getMessage(PagePosition pagePosition) {
-      return messages.get(pagePosition.getMessageNr());
+      final int messageNr = pagePosition.getMessageNr();
+      if (messageNr < 0) {
+         return null;
+      }
+      final int initialOffset = initialMessagesSize();
+      if (messageNr < initialOffset) {
+         return initialMessages[messageNr];
+      }
+      final int index = messageNr - initialOffset;
+      return liveMessages.get(index);
    }
 
    @Override
@@ -73,7 +88,7 @@ public final class LivePageCacheImpl implements LivePageCache {
    @Override
    public void addLiveMessage(PagedMessage message) {
       message.getMessage().usageUp();
-      messages.add(message);
+      liveMessages.add(message);
    }
 
    @Override
@@ -84,7 +99,12 @@ public final class LivePageCacheImpl implements LivePageCache {
 
    @Override
    public PagedMessage[] getMessages() {
-      return messages.toArray(PagedMessage[]::new);
+      final PagedMessage[] pagedMessages = liveMessages.toArray(size -> new PagedMessage[initialMessagesSize() + size], initialMessagesSize());
+      final PagedMessage[] initialMessages = this.initialMessages;
+      if (initialMessages != null) {
+         System.arraycopy(initialMessages, 0, pagedMessages, 0, initialMessages.length);
+      }
+      return pagedMessages;
    }
 
    @Override

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageCacheImpl.java

@@ -17,32 +17,23 @@
 package org.apache.activemq.artemis.core.paging.cursor.impl;
 
 import org.apache.activemq.artemis.core.paging.PagedMessage;
-import org.apache.activemq.artemis.core.paging.cursor.PageCache;
+import org.apache.activemq.artemis.core.paging.cursor.BulkPageCache;
 import org.apache.activemq.artemis.core.paging.cursor.PagePosition;
 
 /**
  * The caching associated to a single page.
  */
-class PageCacheImpl implements PageCache {
+class PageCacheImpl implements BulkPageCache {
 
-   // Constants -----------------------------------------------------
+   private final PagedMessage[] messages;
-
-   // Attributes ----------------------------------------------------
-
-   private PagedMessage[] messages;
 
    private final long pageId;
 
-   // Static --------------------------------------------------------
+   PageCacheImpl(final long pageId, PagedMessage[] messages) {
-
-   // Constructors --------------------------------------------------
-
-   PageCacheImpl(final long pageId) {
       this.pageId = pageId;
+      this.messages = messages;
    }
 
-   // Public --------------------------------------------------------
-
    @Override
    public PagedMessage getMessage(PagePosition pagePosition) {
       if (pagePosition.getMessageNr() < messages.length) {
@@ -57,11 +48,6 @@ class PageCacheImpl implements PageCache {
       return pageId;
    }
 
-   @Override
-   public void setMessages(final PagedMessage[] messages) {
-      this.messages = messages;
-   }
-
    @Override
    public int getNumberOfMessages() {
       return messages.length;

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageCursorProviderImpl.java

@@ -28,8 +28,10 @@ import io.netty.util.collection.LongObjectHashMap;
 import org.apache.activemq.artemis.core.filter.Filter;
 import org.apache.activemq.artemis.core.paging.PagedMessage;
 import org.apache.activemq.artemis.core.paging.PagingStore;
+import org.apache.activemq.artemis.core.paging.cursor.LivePageCache;
 import org.apache.activemq.artemis.core.paging.cursor.NonExistentPage;
 import org.apache.activemq.artemis.core.paging.cursor.PageCache;
+import org.apache.activemq.artemis.core.paging.cursor.BulkPageCache;
 import org.apache.activemq.artemis.core.paging.cursor.PageCursorProvider;
 import org.apache.activemq.artemis.core.paging.cursor.PagePosition;
 import org.apache.activemq.artemis.core.paging.cursor.PageSubscription;
@@ -72,11 +74,11 @@ public class PageCursorProviderImpl implements PageCursorProvider {
    // This is the same executor used at the PageStoreImpl. One Executor per pageStore
    private final ArtemisExecutor executor;
 
-   private final SoftValueLongObjectHashMap<PageCache> softCache;
+   private final SoftValueLongObjectHashMap<BulkPageCache> softCache;
 
    private LongObjectHashMap<Integer> numberOfMessages = null;
 
-   private final LongObjectHashMap<CompletableFuture<PageCache>> inProgressReadPages;
+   private final LongObjectHashMap<CompletableFuture<BulkPageCache>> inProgressReadPages;
 
    private final ConcurrentLongHashMap<PageSubscription> activeCursors = new ConcurrentLongHashMap<>();
 
@@ -162,8 +164,8 @@ public class PageCursorProviderImpl implements PageCursorProvider {
             return null;
          }
          boolean createPage = false;
-         CompletableFuture<PageCache> inProgressReadPage;
+         CompletableFuture<BulkPageCache> inProgressReadPage;
-         PageCache cache;
+         BulkPageCache cache;
          Page page = null;
          synchronized (softCache) {
             cache = softCache.get(pageId);
@@ -184,8 +186,7 @@ public class PageCursorProviderImpl implements PageCursorProvider {
                if (numberOfMessages != null && numberOfMessages.containsKey(pageId)) {
                   return new PageReader(pagingStore.createPage((int) pageId), numberOfMessages.get(pageId));
                }
-               final CompletableFuture<PageCache> readPage = new CompletableFuture<>();
+               final CompletableFuture<BulkPageCache> readPage = new CompletableFuture<>();
-               cache = createPageCache(pageId);
                page = pagingStore.createPage((int) pageId);
                createPage = true;
                inProgressReadPage = readPage;
@@ -193,7 +194,7 @@ public class PageCursorProviderImpl implements PageCursorProvider {
             }
          }
          if (createPage) {
-            return readPage(pageId, page, cache, inProgressReadPage);
+            return readPage(pageId, page, inProgressReadPage);
          } else {
             final long startedWait = System.nanoTime();
             while (true) {
@@ -214,11 +215,11 @@ public class PageCursorProviderImpl implements PageCursorProvider {
 
    private PageCache readPage(long pageId,
                               Page page,
-                              PageCache cache,
+                              CompletableFuture<BulkPageCache> inProgressReadPage) throws Exception {
-                              CompletableFuture<PageCache> inProgressReadPage) throws Exception {
       logger.tracef("adding pageCache pageNr=%d into cursor = %s", pageId, this.pagingStore.getAddress());
       boolean acquiredPageReadPermission = false;
       int num = -1;
+      final PageCacheImpl cache;
       try {
          final long startedRequest = System.nanoTime();
          while (!acquiredPageReadPermission) {
@@ -238,7 +239,7 @@ public class PageCursorProviderImpl implements PageCursorProvider {
                          pagingStore.getAddress(), TimeUnit.NANOSECONDS.toMillis(elapsedReadPage), page.getSize());
          }
          num = pgdMessages.size();
-         cache.setMessages(pgdMessages.toArray(new PagedMessage[num]));
+         cache = new PageCacheImpl(pageId, pgdMessages.toArray(new PagedMessage[num]));
       } catch (Throwable t) {
          inProgressReadPage.completeExceptionally(t);
          synchronized (softCache) {
@@ -268,8 +269,8 @@ public class PageCursorProviderImpl implements PageCursorProvider {
    }
 
    @Override
-   public void addPageCache(PageCache cache) {
+   public void addLivePageCache(LivePageCache cache) {
-      logger.tracef("Add page cache %s", cache);
+      logger.tracef("Add live page cache %s", cache);
       synchronized (softCache) {
          softCache.put(cache.getPageId(), cache);
       }
@@ -537,7 +538,7 @@ public class PageCursorProviderImpl implements PageCursorProvider {
       logger.tracef("this(%s) finishing cleanup on %s", this, depagedPages);
       try {
          for (Page depagedPage : depagedPages) {
-            PageCache cache;
+            BulkPageCache cache;
             PagedMessage[] pgdMessages;
             synchronized (softCache) {
                cache = softCache.get((long) depagedPage.getPageId());
@@ -659,17 +660,6 @@ public class PageCursorProviderImpl implements PageCursorProvider {
          '}';
    }
 
-   // Package protected ---------------------------------------------
-
-   // Protected -----------------------------------------------------
-
-   /* Protected as we may let test cases to instrument the test */
-   protected PageCacheImpl createPageCache(final long pageId) {
-      return new PageCacheImpl(pageId);
-   }
-
-   // Private -------------------------------------------------------
-
    /**
     * This method is synchronized because we want it to be atomic with the cursors being used
     */

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PagePositionImpl.java

@@ -126,11 +126,6 @@ public class PagePositionImpl implements PagePosition {
       } else return Long.compare(recordID, o.getRecordID());
    }
 
-   @Override
-   public PagePosition nextMessage() {
-      return new PagePositionImpl(this.pageNr, this.messageNr + 1);
-   }
-
    @Override
    public PagePosition nextPage() {
       return new PagePositionImpl(this.pageNr + 1, 0, 0);

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageReader.java

@@ -29,7 +29,6 @@ public class PageReader implements PageCache {
 
    private final Page page;
    private final int numberOfMessages;
-   private PagedMessage[] pagedMessages = null;
 
    public PageReader(Page page, int numberOfMessages) {
       this.page = page;
@@ -46,16 +45,10 @@ public class PageReader implements PageCache {
       return numberOfMessages;
    }
 
-   @Override
+   /**
-   public void setMessages(PagedMessage[] messages) {
+    * Used just for testing purposes.
-      this.pagedMessages = messages;
+    */
-   }
+   protected synchronized PagedMessage[] readMessages() {
-
-   @Override
-   public synchronized PagedMessage[] getMessages() {
-      if (pagedMessages != null) {
-         return pagedMessages;
-      } else {
       try {
          openPage();
          return page.read().toArray(new PagedMessage[numberOfMessages]);
@@ -65,7 +58,6 @@ public class PageReader implements PageCache {
          close();
       }
    }
-   }
 
    @Override
    public boolean isLive() {

artemis-server/src/main/java/org/apache/activemq/artemis/core/paging/impl/PagingStoreImpl.java

@@ -478,16 +478,11 @@ public class PagingStoreImpl implements PagingStore {
       Page page = createPage(pageId);
       page.open();
 
-      List<PagedMessage> messages = page.read(storageManager);
+      final List<PagedMessage> messages = page.read(storageManager);
 
-      LivePageCache pageCache = new LivePageCacheImpl(pageId);
+      final PagedMessage[] initialMessages = messages.toArray(new PagedMessage[messages.size()]);
 
-      for (PagedMessage msg : messages) {
+      final LivePageCache pageCache = new LivePageCacheImpl(pageId, initialMessages);
-         pageCache.addLiveMessage(msg);
-         // As we add back to the live page,
-         // we have to discount one when we read the page
-         msg.getMessage().usageDown();
-      }
 
       page.setLiveCache(pageCache);
 
@@ -495,7 +490,7 @@ public class PagingStoreImpl implements PagingStore {
 
       currentPage = page;
 
-      cursorProvider.addPageCache(pageCache);
+      cursorProvider.addLivePageCache(pageCache);
 
       /**
        * The page file might be incomplete in the cases: 1) last message incomplete 2) disk damaged.
@@ -1125,7 +1120,7 @@ public class PagingStoreImpl implements PagingStore {
 
          newPage.setLiveCache(pageCache);
 
-         cursorProvider.addPageCache(pageCache);
+         cursorProvider.addLivePageCache(pageCache);
 
          currentPageSize = 0;
 

artemis-server/src/test/java/org/apache/activemq/artemis/core/paging/cursor/impl/PageReaderTest.java

@@ -50,7 +50,7 @@ public class PageReaderTest extends ActiveMQTestBase {
       int[] offsets = createPage(num);
       PageReader pageReader = getPageReader();
 
-      PagedMessage[] pagedMessages = pageReader.getMessages();
+      PagedMessage[] pagedMessages = pageReader.readMessages();
       assertEquals(pagedMessages.length, num);
 
       PagedMessage pagedMessage = null;
@@ -80,7 +80,7 @@ public class PageReaderTest extends ActiveMQTestBase {
       int[] offsets = createPage(num);
       PageReader pageReader = getPageReader();
 
-      PagedMessage[] pagedMessages = pageReader.getMessages();
+      PagedMessage[] pagedMessages = pageReader.readMessages();
       assertEquals(pagedMessages.length, num);
 
       PagePosition pagePosition = new PagePositionImpl(10, 0);
@@ -108,7 +108,7 @@ public class PageReaderTest extends ActiveMQTestBase {
          int[] offsets = createPage(num);
          PageReader pageReader = getPageReader();
 
-         PagedMessage[] pagedMessages = pageReader.getMessages();
+         PagedMessage[] pagedMessages = pageReader.readMessages();
          assertEquals(pagedMessages.length, num);
 
          PagePosition pagePosition = new PagePositionImpl(10, 0, 50);

tests/performance-jmh/src/main/java/org/apache/activemq/artemis/tests/performance/jmh/ConcurrentAppendOnlyChunkListLookupBenchmark.java

@@ -0,0 +1,80 @@
+/*
+ * 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.activemq.artemis.tests.performance.jmh;
+
+import org.apache.activemq.artemis.utils.collections.ConcurrentAppendOnlyChunkedList;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+@State(Scope.Benchmark)
+@Fork(2)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 8, time = 1)
+public class ConcurrentAppendOnlyChunkListLookupBenchmark {
+
+   private static final Integer MSG = 0;
+
+   @Param({"1000", "10000"})
+   int size;
+
+   @Param({"32"})
+   int chunkSize;
+
+   private ConcurrentAppendOnlyChunkedList<Integer> list;
+
+   @Setup
+   public void init() {
+      list = new ConcurrentAppendOnlyChunkedList<>(chunkSize);
+      for (int i = 0; i < size; i++) {
+         list.add(MSG);
+      }
+   }
+
+   @State(Scope.Thread)
+   public static class Index {
+
+      private int size;
+      private int index;
+
+      @Setup
+      public void init(ConcurrentAppendOnlyChunkListLookupBenchmark benchmark) {
+         index = 0;
+         size = benchmark.size;
+      }
+
+      public int next() {
+         index++;
+         if (index == size) {
+            index = 0;
+            return 0;
+         }
+         return index;
+      }
+   }
+
+   @Benchmark
+   public Integer lookup(Index index) {
+      return list.get(index.next());
+   }
+
+}