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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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/*
 *
 * 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.cassandra.concurrent;

import java.util.concurrent.ExecutorService;

public interface LocalAwareExecutorService extends ExecutorService, ResizableThreadPool
{
    // we need a way to inject a TraceState directly into the Executor context without going through
    // the global Tracing sessions; see CASSANDRA-5668
    void execute(Runnable command, ExecutorLocals locals);

    // permits executing in the context of the submitting thread
    void maybeExecuteImmediately(Runnable command);

    /**
     * Returns the approximate number of threads that are actively
     * executing tasks.
     *
     * @return the number of threads
     */
    int getActiveTaskCount();

    /**
     * Returns the approximate total number of tasks that have
     * completed execution. Because the states of tasks and threads
     * may change dynamically during computation, the returned value
     * is only an approximation, but one that does not ever decrease
     * across successive calls.
     *
     * @return the number of tasks
     */
    long getCompletedTaskCount();

    /**
     * Returns the approximate total of tasks waiting to be executed.
     * Because the states of tasks and threads
     * may change dynamically during computation, the returned value
     * is only an approximation, but one that does not ever decrease
     * across successive calls.
     *
     * @return the number of tasks
     */
    int getPendingTaskCount();

    default int getMaxTasksQueued()
    {
        return -1;
    }

    interface MaximumPoolSizeListener
    {
        /**
         * Listener to follow changes to the maximum pool size
         */
        void onUpdateMaximumPoolSize(int maximumPoolSize);
    }
}