/*
 * 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.flink.streaming.runtime.tasks.mailbox;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.operators.MailboxExecutor;
import org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor;
import org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailbox.MailboxClosedException;
import org.apache.flink.util.Preconditions;
import org.apache.flink.util.WrappingRuntimeException;
import org.apache.flink.util.function.ThrowingRunnable;

import javax.annotation.Nonnull;

import java.util.Optional;
import java.util.concurrent.RejectedExecutionException;

/** Implementation of an executor service build around a mailbox-based execution model. */
@Internal
public final class MailboxExecutorImpl implements MailboxExecutor {

    /** The mailbox that manages the submitted runnable objects. */
    @Nonnull private final TaskMailbox mailbox;

    private final int priority;

    private final StreamTaskActionExecutor actionExecutor;

    private final MailboxProcessor mailboxProcessor;

    public MailboxExecutorImpl(
            @Nonnull TaskMailbox mailbox, int priority, StreamTaskActionExecutor actionExecutor) {
        this(mailbox, priority, actionExecutor, null);
    }

    public MailboxExecutorImpl(
            @Nonnull TaskMailbox mailbox,
            int priority,
            StreamTaskActionExecutor actionExecutor,
            MailboxProcessor mailboxProcessor) {
        this.mailbox = mailbox;
        this.priority = priority;
        this.actionExecutor = Preconditions.checkNotNull(actionExecutor);
        this.mailboxProcessor = mailboxProcessor;
    }

    public boolean isIdle() {
        return !mailboxProcessor.isDefaultActionAvailable()
                && !mailbox.hasMail()
                && mailbox.getState().isAcceptingMails();
    }

    @Override
    public void execute(
            final ThrowingRunnable<? extends Exception> command,
            final String descriptionFormat,
            final Object... descriptionArgs) {
        try {
            mailbox.put(
                    new Mail(
                            command, priority, actionExecutor, descriptionFormat, descriptionArgs));
        } catch (MailboxClosedException mbex) {
            throw new RejectedExecutionException(mbex);
        }
    }

    @Override
    public void yield() throws InterruptedException {
        Mail mail = mailbox.take(priority);
        try {
            mail.run();
        } catch (Exception ex) {
            throw WrappingRuntimeException.wrapIfNecessary(ex);
        }
    }

    @Override
    public boolean tryYield() {
        Optional<Mail> optionalMail = mailbox.tryTake(priority);
        if (optionalMail.isPresent()) {
            try {
                optionalMail.get().run();
            } catch (Exception ex) {
                throw WrappingRuntimeException.wrapIfNecessary(ex);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public boolean shouldInterrupt() {
        // TODO: FLINK-35051 we shouldn't interrupt for every mail, but only for the time sensitive
        // ones, for example related to checkpointing.
        return mailbox.hasMail();
    }
}