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Oracle Coherence Community Edition
/*
* Copyright (c) 2000, 2021, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.io;
import com.oracle.coherence.common.base.Logger;
import java.io.IOException;
import java.lang.ref.WeakReference;
import java.util.Arrays;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.inject.Named;
/**
* A {@link Serializer} implementation that multiplexes serialization/deserialization requests
* across multiple {@link Serializer} implementations.
*
* More specifically, for serialization operations, the list of available {@link Serializer}s are
* iterated over. The first serializer that is able to serialize the object without error, will be
* the {@link Serializer} used for that type going forward.
*
* All serialized payloads will be prefixed with the following header to enable deserialization.
*
*
* +--------------+-------------------------+
* | Length (4) | Serializer Name (1...) |
* +--------------+-------------------------+
* | Serialized Payload (0...) |
* +----------------------------------------+
*
*
* Upon deserialization, the header will be read and the specified {@link Serializer} will be used
* to deserialize the payload. If the header is no present, an {@link IOException} will be thrown.
*
* @since 20.06
*/
@Named("multi")
public class MultiplexingSerializer
implements Serializer, ClassLoaderAware
{
// ----- constructors ---------------------------------------------------
/**
* Construct a new {@link Serializer} that will multiplex serialization operations
* across the provided list of {@link Serializer}s.
*
* It's important to keep in mind that the iteration order when performing serialization/deserialization
* operation is based on the order they are provided. This may have bearing on ordering decisions.
*
* @throws IllegalArgumentException if no {@link Serializer}s are provided, or if the any of the provided
* {@link Serializer}s return {@code null} from {@link Serializer#getName()}
*/
public MultiplexingSerializer(Serializer... serializers)
{
if (serializers == null || serializers.length == 0)
{
throw new IllegalArgumentException("At least one Serializer must be provided.");
}
f_serializers = serializers.clone();
f_idToSerializer = new HashMap<>(serializers.length);
for (int i = 0, len = serializers.length; i < len; i++)
{
Serializer serializer = serializers[i];
if (serializer.getName() == null)
{
String msg = "Serializer '%s' returned a null name";
throw new IllegalArgumentException(String.format(msg, serializer.getClass().getName()));
}
f_idToSerializer.put(serializer.getName(), serializer);
}
}
// ----- Serializer interface -------------------------------------------
@Override
public void serialize(WriteBuffer.BufferOutput out, Object o) throws IOException
{
doSerialization(out, o, f_serializers);
}
@Override
public T deserialize(ReadBuffer.BufferInput in, Class clazz) throws IOException
{
SerializationHeader serializationHeader = readSerializationHeader(in);
if (serializationHeader == null)
{
throw new IOException("Unable to read or missing serialization header");
}
else
{
String serializerName = serializationHeader.getSerializerName();
Serializer serializer = f_idToSerializer.get(serializerName);
if (serializer == null)
{
throw new IOException(String.format("Unknown serializer '%s'", serializerName));
}
int cbPayload = serializationHeader.getLength();
int nOrig = in.getOffset();
// It may be the case that there are multiple serialized objects in a given buffer.
// It was found that some serializers will continue reading from the buffer after
// deserializing an object. So to deal with that, we create a subsequence of the larger
// buffer that contains a single entity to deserialize.
ReadBuffer buffSub = in.getBuffer().getReadBuffer(nOrig, cbPayload);
try
{
return serializer.deserialize(buffSub.getBufferInput(), clazz);
}
finally
{
in.setOffset(nOrig + cbPayload);
}
}
}
@Override
public String getName()
{
return "multi";
}
// ----- ClassLoaderAware interface -------------------------------------
@Override
public ClassLoader getContextClassLoader()
{
WeakReference refLoader = m_refLoader;
return refLoader == null ? null : refLoader.get();
}
@Override
public void setContextClassLoader(ClassLoader loader)
{
assert m_refLoader == null;
if (loader != null)
{
m_refLoader = new WeakReference<>(loader);
for (int i = 0, len = f_serializers.length; i < len; i++)
{
Serializer s = f_serializers[i];
if (s instanceof ClassLoaderAware)
{
((ClassLoaderAware) s).setContextClassLoader(loader);
}
}
}
}
// ----- Object methods -------------------------------------------------
@Override
public String toString()
{
return getName() + ", " + getClass().getName()
+ "{loader=" + getContextClassLoader()
+ ", {serializers=" + Arrays.toString(f_serializers) + '}';
}
// ----- helper methods -------------------------------------------------
/**
* See {@link Serializer#serialize(WriteBuffer.BufferOutput, Object)}
*
* @param out the {@link WriteBuffer.BufferOutput} to write to
* @param o the object to serialize
* @param serializers the {@link Serializer}s to attempt the serialization operation against
*
* @throws IOException if an error occurs during serialization
*/
protected void doSerialization(WriteBuffer.BufferOutput out,
Object o,
Serializer[] serializers) throws IOException
{
String type = o == null ? NULL_TYPE : o.getClass().getName();
Serializer serializer = f_mapTypeToSerializer.get(type);
int nStart = out.getOffset();
if (serializer == null)
{
// Track the errors that each Serializer produces in the situation where ALL
// serializers fail. When this occurs, dump the stack for each error, otherwise
// if one serializer passes, we don't pollute the log with noise.
Map mapError = null;
for (Serializer s : f_serializers)
{
try
{
doWrite(out, o, s);
if (f_mapTypeToSerializer.put(type, s) == null)
{
Logger.fine(() -> String.format("Using serializer '%s' for type '%s'", s.getName(), type));
}
return;
}
catch (Exception e)
{
if (mapError == null)
{
mapError = new LinkedHashMap<>(f_serializers.length);
}
mapError.put(s, e);
out.setOffset(nStart);
Logger.fine(() ->
{
String rawMsg = "Unable to serialize type '%s' using serializer '%s'. This may be expected.";
return String.format(rawMsg, type, s.getName());
});
}
}
logSerializationErrors(mapError, type);
throw new IOException(String.format("No valid serializer available for type '%s'", type));
}
else
{
try
{
doWrite(out, o, serializer);
}
catch (IOException ioe)
{
Logger.fine(() -> "Unexpected exception raised using cached serializer. Trying others...", ioe);
f_mapTypeToSerializer.remove(type);
out.setOffset(nStart);
doSerialization(out, o, Arrays.stream(serializers).filter(s -> s != serializer).toArray(Serializer[]::new));
}
}
}
/**
* Writes the serialization header and payload.
*
* @param out the {@link WriteBuffer.BufferOutput} to write to
* @param o the object to serialize
* @param serializer the {@link Serializer} to use
*
* @throws IOException if an error occurs during serialization
*/
protected void doWrite(WriteBuffer.BufferOutput out, Object o, Serializer serializer)
throws IOException
{
int nStart = out.getOffset();
int nWritten = writeSerializationHeader(out, serializer.getName());
serializer.serialize(out, o);
int nAfterSer = out.getOffset();
int nPayload = nAfterSer - (nStart + nWritten);
// now set the actual length; space previously reserved by writeSerializationHeader.
out.setOffset(nStart);
out.writeInt(nPayload);
out.setOffset(nAfterSer);
}
/**
* Given the provided mappings between a {@link Serializer} and the {@link Exception} it threw, log
* each mapping for diagnostic purposes.
*
* @param serializerExceptionMap a mapping between a {@link Serializer} instance and the {@link Exception}
* it threw for any given serialization operation
* @param typeName The name of the type that produced the error.
*/
protected void logSerializationErrors(Map serializerExceptionMap, String typeName)
{
assert serializerExceptionMap != null && !serializerExceptionMap.isEmpty();
if (Logger.isEnabled(Logger.FINE))
{
String msg = "Unable to serialize/deserialize type '%s' using serializer '%s'.";
for (Map.Entry entry : serializerExceptionMap.entrySet())
{
Logger.fine(String.format(msg, typeName, entry.getKey().getName()), entry.getValue());
}
}
}
/**
* Write the multiplex serialization header.
*
*
* +--------------+-------------------------+
* | Length (4) | Serializer Name (1...) |
* +--------------+-------------------------+
* | Serialized Payload (0...) |
* +----------------------------------------+
*
*
* @param out the stream to write to
* @param serializerName the name of the {@link Serializer}
*
* @throws IOException if an error occurs writing the header or payload
*
* @see Serializer#getName()
*/
protected int writeSerializationHeader(WriteBuffer.BufferOutput out,
String serializerName)
throws IOException
{
int nOff = out.getOffset();
out.setOffset(nOff + Integer.BYTES); // reserve space for the length
out.writeUTF(serializerName);
return out.getOffset() - nOff;
}
/**
* Read the {@link SerializationHeader}.
*
*
* +--------------+-------------------------+
* | Length (4) | Serializer Name (1...) |
* +--------------+-------------------------+
* | Serialized Payload (0...) |
* +----------------------------------------+
*
*
* @param in the stream to read from
*
* @return the SerializationHeader if present and a matching {@link Serializer} is found, otherwise
* returns {@code null}
*/
protected SerializationHeader readSerializationHeader(ReadBuffer.BufferInput in)
{
int nOrig = in.getOffset();
try
{
int cbPayload = in.readInt();
if (cbPayload < 0)
{
in.setOffset(nOrig);
return null;
}
String serializerName = in.readUTF();
return new SerializationHeader(cbPayload, serializerName);
}
catch (IOException ioe)
{
in.setOffset(nOrig);
}
return null;
}
// ----- inner class: SerializationHeader -------------------------------
/**
* Simple wrapper class to hold decorated info added by the serialization process.
*/
protected static final class SerializationHeader
{
// ----- constructors -----------------------------------------------
/**
* Construct a new {@link SerializationHeader}.
*
* @param cbLength the length of the payload associated with this header
* @param serializerName the {@link Serializer} that can handle the payload
*/
private SerializationHeader(int cbLength, String serializerName)
{
f_nLength = cbLength;
f_serializerName = serializerName;
}
// ----- helper methods ---------------------------------------------
/**
* Return the payload length.
*
* @return the payload length
*/
private int getLength()
{
return f_nLength;
}
/**
* Return the {@link Serializer} to handle the payload
*
* @return the {@link Serializer} to handle the payload
*/
private String getSerializerName()
{
return f_serializerName;
}
// ----- data members -----------------------------------------------
/**
* The length, in bytes, of the serialized data.
*/
protected final int f_nLength;
/**
* The name of the serializer that should be used to deserialize the payload.
*/
protected final String f_serializerName;
}
// ----- data members ---------------------------------------------------
/**
* The optional {@link ClassLoader}.
*/
protected WeakReference m_refLoader;
/**
* The {@link Set} {@link Serializer}s to be used by this {@link Serializer}.
*/
protected final Serializer[] f_serializers;
/**
* The mapping of types referenced by their String name and a working
* {@link Serializer} for that type.
*/
protected final ConcurrentMap f_mapTypeToSerializer = new ConcurrentHashMap<>(32);
/**
* The mapping of {@link Serializer}s keyed by their name.
*/
protected final Map f_idToSerializer;
/**
* Symbolic reference for {@code null}.
*/
protected static final String NULL_TYPE = "NULL";
}