Michael Bayne
fcedbe90d7
directly to stderr. Logging an exception with the associated warning does the right thing and logs the stack trace via the logging system. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5318 542714f4-19e9-0310-aa3c-eee0fc999fb1
541 lines
22 KiB
Java
541 lines
22 KiB
Java
//
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// $Id$
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//
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// Narya library - tools for developing networked games
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// Copyright (C) 2002-2007 Three Rings Design, Inc., All Rights Reserved
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// http://www.threerings.net/code/narya/
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.threerings.io;
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import java.lang.reflect.Array;
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import java.lang.reflect.Field;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.lang.reflect.Modifier;
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import java.security.AccessController;
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import java.security.PrivilegedExceptionAction;
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import java.security.PrivilegedActionException;
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import java.io.IOException;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import com.google.common.collect.Lists;
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import com.samskivert.util.ClassUtil;
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import com.samskivert.util.Predicate;
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import static com.threerings.NaryaLog.log;
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/**
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* Handles the streaming of {@link Streamable} instances as well as a set of basic object types
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* (see {@link ObjectOutputStream}). An instance of {@link Streamer} is created for each distinct
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* class that implements {@link Streamable}. The {@link Streamer} reflects on the streamed class
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* and caches the information necessary to efficiently read and write objects of the class in
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* question.
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*/
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public class Streamer
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{
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/**
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* Returns true if the supplied target class can be streamed using a streamer.
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*/
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public synchronized static boolean isStreamable (Class<?> target)
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{
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while (true) {
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// if we've got a streamer for it, it's good
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if (_streamers.containsKey(target)) {
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return true;
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}
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// enums can be streamed
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if (target.isEnum()) {
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return true;
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}
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// if it's not an array, it must be streamable
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if (!target.isArray()) {
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return Streamable.class.isAssignableFrom(target);
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}
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// otherwise extract the component type and loop back around for another check...
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target = target.getComponentType();
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}
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}
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/**
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* Returns the class that should be used when streaming this object. In general that is the
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* object's natural class, but for enum values, that might be its declaring class as enums use
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* classes in a way that would otherwise pollute our id to class mapping space.
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*/
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public static Class<?> getStreamerClass (Object object)
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{
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return (object instanceof Enum) ?
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((Enum<?>)object).getDeclaringClass() : object.getClass();
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}
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/**
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* Obtains a {@link Streamer} that can be used to read and write objects of the specified
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* target class. {@link Streamer} instances are shared among all {@link ObjectInputStream}s and
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* {@link ObjectOutputStream}s.
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*
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* @param target the class that is desired to be streamed. This should be the result of a call
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* to {@link #getStreamerClass} if the caller has an instance they wish to stream.
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*
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* @throws IOException when a streamer is requested for an object that does not implement
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* {@link Streamable} and is not one of the basic object types (@see {@link
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* ObjectOutputStream}).
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*/
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public synchronized static Streamer getStreamer (final Class<?> target)
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throws IOException
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{
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// if we have not yet initialized ourselves, do so now
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if (_streamers == null) {
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createStreamers();
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}
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Streamer stream = _streamers.get(target);
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if (stream == null) {
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// make sure this is a streamable class
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if (!isStreamable(target)) {
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throw new IOException(
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"Requested to stream invalid class '" + target.getName() + "'");
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}
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// create a streamer for this class and cache it
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info("Creating a streamer for '" + target.getName() + "'.");
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}
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// create our streamer in a privileged block so that it can introspect on the to be
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// streamed class
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try {
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stream = AccessController.doPrivileged(new PrivilegedExceptionAction<Streamer>() {
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public Streamer run () throws IOException {
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return new Streamer(target);
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}
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});
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} catch (PrivilegedActionException pae) {
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throw (IOException) pae.getCause();
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}
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_streamers.put(target, stream);
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}
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return stream;
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}
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/**
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* Writes the supplied object to the specified stream.
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*
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* @param object the instance to be written to the stream.
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* @param out the stream to which to write the instance.
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* @param useWriter whether or not to use the custom <code>writeObject</code> if one exists.
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*/
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public void writeObject (Object object, ObjectOutputStream out, boolean useWriter)
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throws IOException
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{
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// if we're supposed to and one exists, use the writer method
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if (useWriter && _writer != null) {
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try {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info("Writing with writer [class=" + _target.getName() + "].");
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}
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_writer.invoke(object, new Object[] { out });
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} catch (Throwable t) {
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if (t instanceof InvocationTargetException) {
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t = ((InvocationTargetException)t).getTargetException();
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}
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if (t instanceof IOException) {
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throw (IOException)t;
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}
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String errmsg = "Failure invoking streamable writer " +
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"[class=" + _target.getName() + "]";
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throw (IOException) new IOException(errmsg).initCause(t);
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}
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return;
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}
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// if we're writing an array, do some special business
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if (_target.isArray()) {
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int length = Array.getLength(object);
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out.writeInt(length);
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// if the component class is final, we can be sure that all instances in the array will
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// be of the same class and thus can serialize things more efficiently
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int cmods = _target.getComponentType().getModifiers();
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if (Modifier.isFinal(cmods)) {
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// compute a mask indicating which elements are null and which are populated
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ArrayMask mask = new ArrayMask(length);
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for (int ii = 0; ii < length; ii++) {
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if (Array.get(object, ii) != null) {
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mask.set(ii);
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}
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}
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// write that mask out to the stream
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mask.writeTo(out);
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// now write out the populated elements
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for (int ii = 0; ii < length; ii++) {
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Object element = Array.get(object, ii);
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if (element != null) {
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out.writeBareObject(element, _delegate, useWriter);
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}
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}
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} else {
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// otherwise we've got to write each array element with its own class identifier
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// because it could be any derived class of the array element type
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for (int ii = 0; ii < length; ii++) {
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out.writeObject(Array.get(object, ii));
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}
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}
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return;
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}
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// if we're writing an enum; write its string value (to avoid future compatibility issues
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// if someone serializes an enum to a file and then adds a value to the enum, changing the
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// ordinal assignments)
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if (_target.isEnum()) {
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out.writeUTF(((Enum<?>)object).name());
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return;
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}
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// otherwise simply write out the fields via our field marshallers
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int fcount = _fields.length;
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for (int ii = 0; ii < fcount; ii++) {
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Field field = _fields[ii];
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FieldMarshaller fm = _marshallers[ii];
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if (fm == null) {
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String errmsg = "Unable to marshall field [class=" + _target.getName() +
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", field=" + field.getName() + ", type=" + field.getType().getName() + "]";
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throw new IOException(errmsg);
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}
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try {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info("Writing field [class=" + _target.getName() +
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", field=" + field.getName() + "].");
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}
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fm.writeField(field, object, out);
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} catch (Exception e) {
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String errmsg = "Failure writing streamable field [class=" + _target.getName() +
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", field=" + field.getName() + "]";
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throw (IOException) new IOException(errmsg).initCause(e);
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}
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}
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}
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/**
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* Creates a blank object that can subsequently be read by this streamer. Data may be read
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* from the input stream as a result of this method (in the case of arrays, the length of the
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* array must be read before creating the array).
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*/
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public Object createObject (ObjectInputStream in)
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throws IOException, ClassNotFoundException
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{
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try {
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// if our target class is an array type, read in the element count and create an array
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// instance of the appropriate type and size
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if (_target.isArray()) {
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int length = in.readInt();
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Creating array '" +
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_target.getComponentType().getName() + "[" + length + "]'.");
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}
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return Array.newInstance(_target.getComponentType(), length);
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} else if (_target.isEnum()) {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Creating enum '" + _target.getName() + "'.");
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}
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@SuppressWarnings("unchecked") Class<EnumReader> eclass =
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(Class<EnumReader>)_target;
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return Enum.valueOf(eclass, in.readUTF());
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} else {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Creating object '" + _target.getName() + "'.");
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}
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return _target.newInstance();
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}
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} catch (InstantiationException ie) {
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String errmsg = "Error instantiating object [type=" + _target.getName() + "]";
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throw (IOException) new IOException(errmsg).initCause(ie);
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} catch (IllegalAccessException iae) {
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String errmsg = "Error instantiating object [type=" + _target.getName() + "]";
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throw (IOException) new IOException(errmsg).initCause(iae);
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}
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}
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/**
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* Reads and populates the fields of the supplied object from the specified stream.
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*
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* @param object the instance to be read from the stream.
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* @param in the stream from which to read the instance.
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* @param useReader whether or not to use the custom <code>readObject</code> if one exists.
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*/
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public void readObject (Object object, ObjectInputStream in, boolean useReader)
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throws IOException, ClassNotFoundException
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{
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// if we're supposed to and one exists, use the reader method
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if (useReader && _reader != null) {
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try {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Reading with reader '" + _target.getName() + "." +
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_reader.getName() + "()'.");
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}
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_reader.invoke(object, new Object[] { in });
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} catch (Throwable t) {
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if (t instanceof InvocationTargetException) {
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t = ((InvocationTargetException)t).getTargetException();
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}
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if (t instanceof IOException) {
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throw (IOException)t;
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}
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String errmsg = "Failure invoking streamable reader " +
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"[class=" + _target.getName() + "]";
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throw (IOException) new IOException(errmsg).initCause(t);
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}
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return;
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}
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Reading '" + _target.getName() + "'.");
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}
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// if we're reading in an array, do some special business
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if (_target.isArray()) {
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int length = Array.getLength(object);
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// if the component class is final, we can be sure that all instances in the array will
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// be of the same class and thus have serialized things more efficiently
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int cmods = _target.getComponentType().getModifiers();
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if (Modifier.isFinal(cmods)) {
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// read in the nullness mask
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ArrayMask mask = new ArrayMask();
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mask.readFrom(in);
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// now read in the array elements given that we know which elements to read
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for (int ii = 0; ii < length; ii++) {
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if (mask.isSet(ii)) {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Reading fixed element '" + ii + "'.");
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}
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Object element = _delegate.createObject(in);
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in.readBareObject(element, _delegate, useReader);
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Array.set(object, ii, element);
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} else if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Skipping null element '" + ii + "'.");
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}
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}
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} else {
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// otherwise we had to write each object out individually
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for (int ii = 0; ii < length; ii++) {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Reading free element '" + ii + "'.");
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}
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Array.set(object, ii, in.readObject());
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}
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}
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return;
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}
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// an enum has no additional state
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if (_target.isEnum()) {
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return;
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}
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// otherwise simply read the fields via our field marshallers
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int fcount = _fields.length;
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for (int ii = 0; ii < fcount; ii++) {
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Field field = _fields[ii];
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FieldMarshaller fm = _marshallers[ii];
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if (fm == null) {
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String errmsg = "Unable to marshall field [class=" + _target.getName() +
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", field=" + field.getName() + ", type=" + field.getType().getName() + "]";
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throw new IOException(errmsg);
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}
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try {
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Reading field '" + field.getName() + "' " +
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"with " + fm + ".");
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}
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// gracefully deal with objects that have had new fields added to their class
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// definition
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if (in.available() > 0) {
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fm.readField(field, object, in);
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} else {
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log.info("Streamed instance missing field (probably newly added) " +
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"[class=" + _target.getName() + ", field=" + field.getName() + "].");
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}
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} catch (Exception e) {
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String errmsg = "Failure reading streamable field [class=" + _target.getName() +
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", field=" + field.getName() + ", error=" + e + "]";
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throw (IOException) new IOException(errmsg).initCause(e);
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}
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}
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info(in.hashCode() + ": Read object '" + object + "'.");
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}
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}
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@Override
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public String toString ()
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{
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return (_target == null) ? getClass().getName() :
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"[target=" + _target.getName() + ", delegate=" + _delegate +
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", fcount=" + (_fields == null ? 0 : _fields.length) +
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", reader=" + _reader + ", writer=" + _writer + "]";
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}
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/**
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* The constructor used by the basic streamers.
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*/
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protected Streamer ()
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{
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}
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/**
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* Constructs a streamer for the specified target class.
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*/
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protected Streamer (Class<?> target)
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throws IOException
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{
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// keep a handle on the class
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_target = target;
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// if this is a non-static inner class, freak out because we cannot stream those
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boolean isInner = false, isStatic = Modifier.isStatic(_target.getModifiers());
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try {
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isInner = (_target.getDeclaringClass() != null);
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} catch (Throwable t) {
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log.warning("Failure checking innerness of class [class=" + _target.getName() +
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", error=" + t + "].");
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}
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if (isInner && !isStatic) {
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throw new IllegalArgumentException(
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"Cannot stream non-static inner class: " + _target.getName());
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}
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// if our target class is an array, we want to get a handle on a streamer delegate that
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// we'll use to stream our elements
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if (_target.isArray()) {
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_delegate = Streamer.getStreamer(_target.getComponentType());
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// sanity check
|
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if (_delegate == null) {
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String errmsg = "Aiya! Streamer created for array type but we have no registered " +
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"streamer for the element type [type=" + _target.getName() + "]";
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throw new RuntimeException(errmsg);
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}
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// and that's all we'll need
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return;
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}
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// look up the reader and writer methods
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try {
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_reader = target.getMethod(READER_METHOD_NAME, READER_ARGS);
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} catch (NoSuchMethodException nsme) {
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// nothing to worry about, we just don't have one
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}
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try {
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_writer = target.getMethod(WRITER_METHOD_NAME, WRITER_ARGS);
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} catch (NoSuchMethodException nsme) {
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// nothing to worry about, we just don't have one
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}
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// reflect on all the object's fields and remove all marked with NotStreamable
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List<Field> fieldList = Lists.newArrayList();
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ClassUtil.getFields(target, fieldList);
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_isStreamableFieldPred.filter(fieldList);
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_fields = fieldList.toArray(new Field[fieldList.size()]);
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int fcount = _fields.length;
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// obtain field marshallers for all of our fields
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_marshallers = new FieldMarshaller[fcount];
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for (int ii = 0; ii < fcount; ii++) {
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_marshallers[ii] = FieldMarshaller.getFieldMarshaller(_fields[ii]);
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if (ObjectInputStream.STREAM_DEBUG) {
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log.info("Using " + _marshallers[ii] + " for " + _target.getName() + "." +
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_fields[ii].getName() + ".");
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}
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}
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}
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/**
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* Creates our streamers table and registers streamers for all of the basic types.
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*/
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protected static void createStreamers ()
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{
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_streamers = new HashMap<Class<?>, Streamer>();
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// register all of the basic streamers
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int bscount = BasicStreamers.BSTREAMER_TYPES.length;
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for (int ii = 0; ii < bscount; ii++) {
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_streamers.put(BasicStreamers.BSTREAMER_TYPES[ii],
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BasicStreamers.BSTREAMER_INSTANCES[ii]);
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}
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}
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|
|
/** Used to coerce the type system into quietude when reading enums from the wire. */
|
|
protected static enum EnumReader { NOT_USED };
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|
|
|
/** The class for which this streamer instance is configured. */
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|
protected Class<?> _target;
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/** If our target class is an array, this is a reference to a streamer that can stream our
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* array elements, otherwise it is null. */
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protected Streamer _delegate;
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/** The non-transient, non-static public fields that we will stream when requested. */
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protected Field[] _fields;
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|
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/** Field marshallers for each field that will be read or written in our objects. */
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protected FieldMarshaller[] _marshallers;
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|
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/** A reference to the <code>readObject</code> method if one is defined by our target class. */
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|
protected Method _reader;
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/** A reference to the <code>writeObject</code> method if one is defined by our target
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|
* class. */
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protected Method _writer;
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|
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|
/** Contains the mapping from class names to configured streamer instances. */
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|
protected static Map<Class<?>, Streamer> _streamers;
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|
|
/** A simple predicate to filter "NotStreamable" members from a Streamable object's fields. */
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|
protected static final Predicate<Field> _isStreamableFieldPred = new Predicate<Field>() {
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|
@Override public boolean isMatch (Field obj) {
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|
return (obj.getAnnotation(NotStreamable.class) == null);
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|
}
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|
};
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|
|
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/** The name of the custom reader method. */
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|
protected static final String READER_METHOD_NAME = "readObject";
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|
|
|
/** The argument list for the custom reader method. */
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|
protected static final Class<?>[] READER_ARGS = { ObjectInputStream.class };
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|
|
|
/** The name of the custom writer method. */
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|
protected static final String WRITER_METHOD_NAME = "writeObject";
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|
|
|
/** The argument list for the custom writer method. */
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|
protected static final Class<?>[] WRITER_ARGS = { ObjectOutputStream.class };
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|
}
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