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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * 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. See accompanying
 * LICENSE file.
 */

package com.gemstone.gemfire.internal.cache;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import com.gemstone.gemfire.CopyHelper;
import com.gemstone.gemfire.DataSerializer;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.internal.DataSerializableFixedID;
import com.gemstone.gemfire.internal.LogWriterImpl;
import com.gemstone.gemfire.internal.cache.lru.LRUEntry;
import com.gemstone.gemfire.internal.i18n.LocalizedStrings;
import com.gemstone.gemfire.internal.shared.Version;
import com.gemstone.gemfire.pdx.PdxInstance;

/**
 * The first time someone asks this instance for its Object it will deserialize
 * the bytes and from then on keep a reference to the deserialized form.
 * So it "prefers deserialization".
 * @author Eric Zoerner
 *
 */
public final class VMCachedDeserializable implements CachedDeserializable, DataSerializableFixedID {
  
  /** The cached value */
  private volatile Object value;
  private int valueSize; // only set in constructor or fromData

  /**
   * +PER_OBJECT_OVERHEAD for VMCachedDeserializable object
   * +4 for value field
   * +4 for valueSize field
   */
  static final int MEM_OVERHEAD = PER_OBJECT_OVERHEAD + 4 + 4;
  /**
   * zero-arg constructor for serialization only
   */
  public VMCachedDeserializable() {
  }
  /** 
   * Creates a new instance of VMCachedDeserializable.
   *
   * Note that, in general, instances of this class should be obtained
   * via {@link CachedDeserializableFactory}.
   */
  VMCachedDeserializable(byte[] serializedValue) {
    if (serializedValue == null)
      throw new NullPointerException(LocalizedStrings.VMCachedDeserializable_VALUE_MUST_NOT_BE_NULL.toLocalizedString());
    this.value = serializedValue;
    this.valueSize = CachedDeserializableFactory.getByteSize(serializedValue);
  }

  VMCachedDeserializable(VMCachedDeserializable cd) {
    this.value = cd.value;
    this.valueSize = cd.valueSize;
  }

  /**
   * Create a new instance with an object and it's size.
   * Note the caller decides if objectSize is the memory size or the serialized size.
   * @param object
   * @param objectSize
   */
  public VMCachedDeserializable(Object object, int objectSize) {
    this.value = object;
    this.valueSize = objectSize;
  }
  
  public Object getDeserializedValue(Region r, RegionEntry re) {
    Object v = this.value;
    if (v instanceof byte[]) {
//       com.gemstone.gemfire.internal.cache.GemFireCache.getInstance().getLogger().info("DEBUG getDeserializedValue r=" + r + " re=" + re, new RuntimeException("STACK"));
      LRUEntry le = null;
      if (re != null) {
        assert r != null;
        if (re instanceof LRUEntry) {
          le = (LRUEntry)re;
        }
      }
      if (le != null) {
        if (r instanceof PartitionedRegion) {
          r = ((PartitionedRegion)r).getBucketRegion(re.getKeyCopy());
        }
        boolean callFinish = false;
        AbstractLRURegionMap lruMap = null;
        if (r != null) { // fix for bug 44795
          lruMap = (AbstractLRURegionMap)((LocalRegion)r).getRegionMap();
        }
        boolean threadAlreadySynced = Thread.holdsLock(le);
        boolean isCacheListenerInvoked = re.isCacheListenerInvocationInProgress();
        synchronized (le) {
          v = this.value;
          if (!(v instanceof byte[])) return v;
          v = EntryEventImpl.deserialize((byte[])v);
          if (threadAlreadySynced && !isCacheListenerInvoked) {
            // to fix bug 43355 and 43409 don't change the value form
            // if the thread that called us was already synced.
            return v;
          }
          if (!(v instanceof PdxInstance)) {
            this.value = v;
            if (lruMap != null) {
              callFinish = lruMap.beginChangeValueForm(le, this, v);
            }
          }
        }
        if (callFinish && !isCacheListenerInvoked) {
          lruMap.finishChangeValueForm();
        }
      } else {
        // we sync on this so we will only do one deserialize
        synchronized (this) {
          v = this.value;
          if (!(v instanceof byte[])) return v;
          v = EntryEventImpl.deserialize((byte[])v);
          if (!(v instanceof PdxInstance)) {
            this.value = v;
          }
          //           ObjectSizer os = null;
          //           if (r != null) {
          //             EvictionAttributes ea = r.getAttributes().getEvictionAttributes();
          //             if (ea != null) {
          //               os = ea.getObjectSizer();
          //             }
          //             int vSize = CachedDeserializableFactory.calcMemSize(v, os, false, false);
          //             if (vSize != -1) {
          //               int oldSize = this.valueSize;
          //               this.valueSize = vSize;
          //               if (r instanceof BucketRegion) {
          //                 BucketRegion br = (BucketRegion)r;
          //                 br.updateBucketMemoryStats(vSize - oldSize);
          //               }
          //               // @todo do we need to update some lru stats since the size changed?
          //             }
          //             // If vSize == -1 then leave valueSize as is which is the serialized size.
        }
      }
    }
    return v;
  }  
  public Object getDeserializedForReading() {
    Object v = this.value;
    if (v instanceof byte[]) {
      return EntryEventImpl.deserialize((byte[])v);
    } else {
      return v;
    }
  }
  public Object getDeserializedWritableCopy(Region r, RegionEntry re) {
    Object v = this.value;
    if (v instanceof byte[]) {
      Object result =  EntryEventImpl.deserialize((byte[])v);
      if (CopyHelper.isWellKnownImmutableInstance(result, result.getClass())
          && !(result instanceof PdxInstance)) {
        // Since it is immutable go ahead and change the form
        // since we can return the immutable instance each time.
        result = getDeserializedValue(r, re);
      }
      return result;
    } else {
      return CopyHelper.copy(v);
    }
  }
 
  /**
   * Return the serialized value as a byte[]
   */
  public byte[] getSerializedValue() {
    Object v = this.value;
    if (v instanceof byte[])
      return (byte[])v;
    return EntryEventImpl.serialize(v);
  }

  /**
   * Return current value regardless of whether it is serialized or
   * deserialized: if it was serialized than it is a byte[], otherwise
   * it is not a byte[].
   */
  public Object getValue() {
    return this.value;
  }

  public int getSizeInBytes() {
    return MEM_OVERHEAD + this.valueSize;
  }
  
  public int getValueSizeInBytes() {
    return valueSize;
  }

  public int getDSFID() {
    return VM_CACHED_DESERIALIZABLE;
  }

  public void fromData(DataInput in) throws IOException, ClassNotFoundException {
    // fix for bug 38309
    byte[] bytes = DataSerializer.readByteArray(in);
    this.valueSize = bytes.length;
    this.value = bytes;
  }

  public void toData(DataOutput out) throws IOException {
    // fix for bug 38309
    DataSerializer.writeObjectAsByteArray(getValue(), out);
  }

  String getShortClassName() {
    String cname = getClass().getName();
    return cname.substring(getClass().getPackage().getName().length()+1);
  }

  @Override
  public String toString() {
    return getShortClassName() + '@' + this.hashCode();
  }

  public void writeValueAsByteArray(DataOutput out) throws IOException {
    toData(out);
  }
  
  public void fillSerializedValue(BytesAndBitsForCompactor wrapper, byte userBits)
  {
    Object v = this.value;    
    if (v instanceof byte[]) {     
      wrapper.setData((byte[])v, userBits, ((byte[])v).length, false /* Not Reusable as it refers to underlying value*/);
    }else {
      EntryEventImpl.fillSerializedValue(wrapper, v, userBits);
    }
    
  }
  public String getStringForm() {
    try {
      return LogWriterImpl.forceToString(getDeserializedForReading());
    } catch (RuntimeException ex) {
      return "Could not convert object to string because " + ex;
    }
  }
  @Override
  public Version[] getSerializationVersions() {
    return null;
  }
}





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