content: /*
   * Copyright 2014-2025 Real Logic Limited.
   *
   * Licensed 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
   *
   * https://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 io.aeron.driver;
  
  import io.aeron.driver.media.UdpChannel;
  import io.aeron.protocol.ErrorFlyweight;
  import io.aeron.protocol.SetupFlyweight;
  import io.aeron.protocol.StatusMessageFlyweight;
  import org.agrona.concurrent.status.CountersManager;
  
  import java.net.InetSocketAddress;
  
  import static io.aeron.logbuffer.LogBufferDescriptor.computePosition;
  
  /**
   * Default multicast sender flow control strategy.
   * <p>
   * Max of right edges.
   * No tracking of receivers.
   */
  public class MaxMulticastFlowControl implements FlowControl
  {
      /**
       * URI param value to identify this {@link FlowControl} strategy.
       */
      public static final String FC_PARAM_VALUE = "max";
  
      /**
       * Multiple of receiver window to allow for a retransmit action.
       */
      private int retransmitReceiverWindowMultiple;
  
      /**
       * {@inheritDoc}
       */
      public void initialize(
          final MediaDriver.Context context,
          final CountersManager countersManager,
          final UdpChannel udpChannel,
          final int streamId,
          final int sessionId,
          final long registrationId,
          final int initialTermId,
          final int termBufferLength)
      {
          retransmitReceiverWindowMultiple = FlowControl.retransmitReceiverWindowMultiple(
              udpChannel,
              context.multicastFlowControlRetransmitReceiverWindowMultiple()
          );
      }
  
      /**
       * {@inheritDoc}
       */
      public void close()
      {
      }
  
      /**
       * {@inheritDoc}
       */
      public long onStatusMessage(
          final StatusMessageFlyweight flyweight,
          final InetSocketAddress receiverAddress,
          final long senderLimit,
          final int initialTermId,
          final int positionBitsToShift,
          final long timeNs)
      {
          final long position = computePosition(
              flyweight.consumptionTermId(),
              flyweight.consumptionTermOffset(),
              positionBitsToShift,
              initialTermId);
  
          return Math.max(senderLimit, position + flyweight.receiverWindowLength());
      }
  
      /**
       * {@inheritDoc}
       */
      public void onTriggerSendSetup(
          final StatusMessageFlyweight flyweight,
          final InetSocketAddress receiverAddress,
          final long timeNs)
      {
      }
  
      /**
       * {@inheritDoc}
       */
      public long onSetup(
          final SetupFlyweight flyweight,
          final long senderLimit,
          final long senderPosition,
          final int positionBitsToShift,
          final long timeNs)
      {
          return senderLimit;
      }
  
      /**
       * {@inheritDoc}
       */
      public long onIdle(final long timeNs, final long senderLimit, final long senderPosition, final boolean isEos)
      {
          return senderLimit;
      }
  
      /**
       * {@inheritDoc}
       */
      public void onError(final ErrorFlyweight errorFlyweight, final InetSocketAddress receiverAddress, final long timeNs)
      {
      }
  
      /**
       * {@inheritDoc}
       */
      public boolean hasRequiredReceivers()
      {
          return true;
      }
  
      /**
       * {@inheritDoc}
       */
      public int maxRetransmissionLength(
          final int termOffset,
          final int resendLength,
          final int termBufferLength,
          final int mtuLength)
      {
          return FlowControl.calculateRetransmissionLength(
              resendLength, termBufferLength, termOffset, retransmitReceiverWindowMultiple);
      }
  }
  