[GitHub] [iotdb] Alima777 commented on a diff in pull request #8957: [IOTDB-5449] Allow query scheduler to receive more tasks

["Alima777 (via GitHub)" <gi...@apache.org>]

Alima777 commented on code in PR #8957:
URL: https://github.com/apache/iotdb/pull/8957#discussion_r1096913283


##########
server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/queue/IndexedBlockingReserveQueue.java:
##########
@@ -0,0 +1,86 @@
+/*
+ * 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.iotdb.db.mpp.execution.schedule.queue;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * This class is different from <class>IndexedBlockingQueue</class> in that it will reserve space
+ * for polled element in case it will be pushed again.
+ */
+public abstract class IndexedBlockingReserveQueue<E extends IDIndexedAccessible>
+    extends IndexedBlockingQueue<E> {
+
+  // To avoid some elements can't join the queue again that are polled out for running or blocked
+  private int reservedSize;
+
+  public IndexedBlockingReserveQueue(int maxCapacity, E queryHolder) {
+    super(maxCapacity, queryHolder);
+  }
+
+  /**
+   * Get and remove the first element of the queue. Reserve space for this polled element.
+   *
+   * @return the queue head element.
+   */
+  public synchronized E poll() throws InterruptedException {
+    while (isEmpty()) {
+      this.wait();
+    }
+    E output = pollFirst();
+    size--;
+    reservedSize++;
+    return output;
+  }
+
+  public synchronized void push(E element) {
+    if (element == null) {
+      throw new NullPointerException("pushed element is null");
+    }
+    Preconditions.checkState(
+        !contains(element),
+        "The queue has already contained the element: " + element.getDriverTaskId());
+    Preconditions.checkState(
+        size + reservedSize < MAX_CAPACITY, "The system can't allow more query tasks.");
+    pushToQueue(element);
+    size++;
+    this.notifyAll();
+  }
+
+  /**
+   * RePush an element which is polled out for running or blocked before to the queue. In this case,
+   * we don't increase the current size of queue, since we have reserved a place for it.
+   */
+  public synchronized void repush(E element) {
+    if (element == null) {
+      throw new NullPointerException("pushed element is null");
+    }
+    pushToQueue(element);
+    reservedSize--;

Review Comment:
   Fixed.



##########
server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/queue/IndexedBlockingReserveQueue.java:
##########
@@ -0,0 +1,92 @@
+/*
+ * 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.iotdb.db.mpp.execution.schedule.queue;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * This class is different from <class>IndexedBlockingQueue</class> in that it will reserve space
+ * for polled element in case it will be pushed again.
+ */
+public abstract class IndexedBlockingReserveQueue<E extends IDIndexedAccessible>
+    extends IndexedBlockingQueue<E> {
+
+  // To avoid some elements can't join the queue again that are polled out for running or blocked
+  private int reservedSize;
+
+  public IndexedBlockingReserveQueue(int maxCapacity, E queryHolder) {
+    super(maxCapacity, queryHolder);
+  }
+
+  /**
+   * Get and remove the first element of the queue. Reserve space for this polled element.
+   *
+   * @return the queue head element.
+   */
+  public synchronized E poll() throws InterruptedException {
+    while (isEmpty()) {
+      this.wait();
+    }
+    E output = pollFirst();
+    size--;
+    reservedSize++;
+    return output;
+  }
+
+  public synchronized void push(E element) {
+    if (element == null) {
+      throw new NullPointerException("pushed element is null");
+    }
+    Preconditions.checkState(
+        !contains(element),
+        "The queue has already contained the element: " + element.getDriverTaskId());

Review Comment:
   Yes, I think so.



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