Package com.esotericsoftware.kryo.serializers

Source Code of com.esotericsoftware.kryo.serializers.CompatibleFieldSerializer

package com.esotericsoftware.kryo.serializers;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.InputChunked;
import com.esotericsoftware.kryo.io.Output;
import com.esotericsoftware.kryo.io.OutputChunked;
import com.esotericsoftware.kryo.util.ObjectMap;

import static com.esotericsoftware.minlog.Log.*;

/** Serializes objects using direct field assignment, with limited support for forward and backward compatibility. Fields can be
* added or removed without invalidating previously serialized bytes. Note that changing the type of a field is not supported.
* <p>
* There is additional overhead compared to {@link FieldSerializer}. A header is output the first time an object of a given type
* is serialized. The header consists of an int for the number of fields, then a String for each field name. Also, to support
* skipping the bytes for a field that no longer exists, for each field value an int is written that is the length of the value in
* bytes.
* <p>
* Note that the field data is identified by name. The situation where a super class has a field with the same name as a subclass
* must be avoided.
* @author Nathan Sweet <misc@n4te.com> */
public class CompatibleFieldSerializer<T> extends FieldSerializer<T> {
  public CompatibleFieldSerializer (Kryo kryo, Class type) {
    super(kryo, type);
  }

  public void write (Kryo kryo, Output output, T object) {
    CachedField[] fields = getFields();
    ObjectMap context = kryo.getGraphContext();
    if (!context.containsKey(this)) {
      context.put(this, null);
      if (TRACE) trace("kryo", "Write " + fields.length + " field names.");
      output.writeVarInt(fields.length, true);
      for (int i = 0, n = fields.length; i < n; i++)
        output.writeString(fields[i].field.getName());
    }

    OutputChunked outputChunked = new OutputChunked(output, 1024);
    for (int i = 0, n = fields.length; i < n; i++) {
      fields[i].write(outputChunked, object);
      outputChunked.endChunks();
    }
  }

  public T read (Kryo kryo, Input input, Class<T> type) {
    T object = create(kryo, input, type);
    kryo.reference(object);
    ObjectMap context = kryo.getGraphContext();
    CachedField[] fields = (CachedField[])context.get(this);
    if (fields == null) {
      int length = input.readVarInt(true);
      if (TRACE) trace("kryo", "Read " + length + " field names.");
      String[] names = new String[length];
      for (int i = 0; i < length; i++)
        names[i] = input.readString();

      fields = new CachedField[length];
      CachedField[] allFields = getFields();
      outer:
      for (int i = 0, n = names.length; i < n; i++) {
        String schemaName = names[i];
        for (int ii = 0, nn = allFields.length; ii < nn; ii++) {
          if (allFields[ii].field.getName().equals(schemaName)) {
            fields[i] = allFields[ii];
            continue outer;
          }
        }
        if (TRACE) trace("kryo", "Ignore obsolete field: " + schemaName);
      }
      context.put(this, fields);
    }

    InputChunked inputChunked = new InputChunked(input, 1024);
    for (int i = 0, n = fields.length; i < n; i++) {
      CachedField cachedField = fields[i];
      if (cachedField == null) {
        if (TRACE) trace("kryo", "Skip obsolete field.");
        inputChunked.nextChunks();
        continue;
      }
      cachedField.read(inputChunked, object);
      inputChunked.nextChunks();
    }
    return object;
  }
}
TOP

Related Classes of com.esotericsoftware.kryo.serializers.CompatibleFieldSerializer

TOP
Copyright © 2018 www.massapi.com. All rights reserved.
All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.