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    • swim.runtime.downlink.ValueDownlinkModel Maven / Gradle / Ivy

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    // Copyright 2015-2019 SWIM.AI inc.
//
// 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
//
//     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 swim.runtime.downlink;

import java.util.Map;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import swim.structure.Form;
import swim.structure.Value;
import swim.uri.Uri;
import swim.warp.EventMessage;

public class ValueDownlinkModel extends DemandDownlinkModem> {
  protected int flags;
  protected volatile Value state;

  public ValueDownlinkModel(Uri meshUri, Uri hostUri, Uri nodeUri, Uri laneUri,
                            float prio, float rate, Value body) {
    super(meshUri, hostUri, nodeUri, laneUri, prio, rate, body);
    this.flags = 0;
  }

  public final boolean isStateful() {
    return (this.flags & STATEFUL) != 0;
  }

  public ValueDownlinkModel isStateful(boolean isStateful) {
    if (isStateful) {
      this.flags |= STATEFUL;
    } else {
      this.flags &= ~STATEFUL;
    }
    final Object views = this.views;
    if (views instanceof DownlinkView) {
      ((ValueDownlinkView) views).didSetStateful(isStateful);
    } else if (views instanceof DownlinkView[]) {
      final DownlinkView[] viewArray = (DownlinkView[]) views;
      for (int i = 0, n = viewArray.length; i < n; i += 1) {
        ((ValueDownlinkView) viewArray[i]).didSetStateful(isStateful);
      }
    }
    return this;
  }

  @Override
  protected void pushDownEvent(EventMessage message) {
    new ValueDownlinkRelaySet(this, message, message.body()).run();
  }

  @Override
  protected Value nextUpCue() {
    return this.state;
  }

  @Override
  protected void didAddDownlink(ValueDownlinkView view) {
    if (this.views instanceof DownlinkView) {
      isStateful(((ValueDownlinkView) view).isStateful());
    }
  }

  public Value get() {
    return this.state;
  }

  @SuppressWarnings("unchecked")
  public  V set(ValueDownlinkView view, V newObject) {
    final Form valueForm = view.valueForm;
    final Value newValue = valueForm.mold(newObject).toValue();
    final ValueDownlinkRelaySet relay = new ValueDownlinkRelaySet(this, newValue);
    relay.valueForm = (Form) valueForm;
    relay.oldObject = newObject;
    relay.newObject = newObject;
    relay.stage = view.stage;
    relay.run();
    if (relay.isDone()) {
      if (relay.valueForm != valueForm && valueForm != null) {
        relay.oldObject = valueForm.cast(relay.oldValue);
        if (relay.oldObject == null) {
          relay.oldObject = valueForm.unit();
        }
      }
      return (V) relay.oldObject;
    } else {
      return null;
    }
  }

  public Value setValue(Value newValue) {
    final ValueDownlinkRelaySet relay = new ValueDownlinkRelaySet(this, newValue);
    relay.run();
    if (relay.isDone()) {
      return relay.oldValue;
    } else {
      return Value.absent();
    }
  }

  protected Value willSet(Value newValue) {
    return newValue;
  }

  protected void didSet(Value newValue, Value oldValue) {
  }

  protected static final int STATEFUL = 1 << 0;

  static final AtomicReferenceFieldUpdater STATE =
      AtomicReferenceFieldUpdater.newUpdater(ValueDownlinkModel.class, Value.class, "state");
}

final class ValueDownlinkRelaySet extends DownlinkRelay> {
  final EventMessage message;
  Form valueForm;
  Value oldValue;
  Value newValue;
  Object oldObject;
  Object newObject;

  ValueDownlinkRelaySet(ValueDownlinkModel model, EventMessage message, Value newValue) {
    super(model, 4);
    this.message = message;
    this.newValue = newValue;
  }

  ValueDownlinkRelaySet(ValueDownlinkModel model, Value newValue) {
    super(model, 1, 3);
    this.message = null;
    this.newValue = newValue;
  }

  @Override
  void beginPhase(int phase) {
    if (phase == 1) {
      this.newValue = this.model.willSet(this.newValue);
    } else if (phase == 2) {
      if (this.model.isStateful()) {
        do {
          this.oldValue = this.model.state;
        } while (this.oldValue != this.newValue && !ValueDownlinkModel.STATE.compareAndSet(this.model, this.oldValue, this.newValue));
      }
      this.model.didSet(this.newValue, this.oldValue);
    }
  }

  @SuppressWarnings("unchecked")
  @Override
  boolean runPhase(ValueDownlinkView view, int phase, boolean preemptive) {
    if (phase == 0) {
      if (preemptive) {
        view.downlinkWillReceive(this.message);
      }
      return view.dispatchWillReceive(this.message.body(), preemptive);
    } else if (phase == 1) {
      this.newValue = view.downlinkWillSetValue(this.newValue);
      final Form valueForm = (Form) view.valueForm();
      if (this.valueForm != valueForm && valueForm != null) {
        this.valueForm = valueForm;
        this.oldObject = valueForm.cast(this.newValue);
        if (this.oldObject == null) {
          this.oldObject = valueForm.unit();
        }
      }
      if (preemptive) {
        this.newObject = ((ValueDownlinkView) view).downlinkWillSet(this.oldObject);
      }
      final Map.Entry result = ((ValueDownlinkView) view).dispatchWillSet(this.oldObject, preemptive);
      this.newObject = result.getValue();
      if (this.oldObject != this.newObject) {
        this.oldObject = this.newObject;
        this.newValue = valueForm.mold(this.newObject).toValue();
      }
      return result.getKey();
    } else if (phase == 2) {
      view.downlinkDidSetValue(this.newValue, this.oldValue);
      final Form valueForm = (Form) view.valueForm();
      if (this.valueForm != valueForm && valueForm != null) {
        this.valueForm = valueForm;
        this.oldObject = valueForm.cast(this.oldValue);
        if (this.oldObject == null) {
          this.oldObject = valueForm.unit();
        }
        this.newObject = valueForm.cast(this.newValue);
        if (this.newObject == null) {
          this.newObject = valueForm.unit();
        }
      }
      if (preemptive) {
        ((ValueDownlinkView) view).downlinkDidSet(this.newObject, this.oldObject);
      }
      return ((ValueDownlinkView) view).dispatchDidSet(this.newObject, this.oldObject, preemptive);
    } else if (phase == 3) {
      if (preemptive) {
        view.downlinkDidReceive(this.message);
      }
      return view.dispatchDidReceive(this.message.body(), preemptive);
    } else {
      throw new AssertionError(); // unreachable
    }
  }

  @Override
  void done() {
    if (this.message != null) {
      this.model.cueDown();
    } else {
      this.model.cueUp();
    }
  }
}
    
    
    
    

    




    
    
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