package org.jgroups;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jgroups.conf.ClassConfigurator;
import org.jgroups.stack.IpAddress;
import org.jgroups.util.Buffer;
import org.jgroups.util.Headers;
import org.jgroups.util.Streamable;
import org.jgroups.util.Util;
import java.io.*;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* A Message encapsulates data sent to members of a group. It contains among other things the
* address of the sender, the destination address, a payload (byte buffer) and a list of
* headers. Headers are added by protocols on the sender side and removed by protocols
* on the receiver's side.
* <p>
* The byte buffer can point to a reference, and we can subset it using index and length. However,
* when the message is serialized, we only write the bytes between index and length.
* @author Bela Ban
* @version $Id: Message.java,v 1.94 2008/11/11 09:30:08 belaban Exp $
*/
public class Message implements Streamable {
protected Address dest_addr=null;
protected Address src_addr=null;
/** The payload */
private byte[] buf=null;
/** The index into the payload (usually 0) */
protected int offset=0;
/** The number of bytes in the buffer (usually buf.length is buf not equal to null). */
protected int length=0;
/** All headers are placed here */
protected Headers headers;
private byte flags;
protected static final Log log=LogFactory.getLog(Message.class);
static final Set<Class> nonStreamableHeaders=new HashSet<Class>();
static final byte DEST_SET = 1;
static final byte SRC_SET = 2;
static final byte BUF_SET = 4;
// static final byte HDRS_SET=8; // bela July 15 2005: not needed, we always create headers
static final byte IPADDR_DEST = 16;
static final byte IPADDR_SRC = 32;
static final byte SRC_HOST_NULL = 64;
// =========================== Flags ==============================
public static final byte OOB = 1;
public static final byte LOW_PRIO = 2; // not yet sure if we want this flag...
public static final byte HIGH_PRIO = 4; // not yet sure if we want this flag...
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> then the message sent to the group.
* Otherwise, it contains a single destination and is sent to that member.<p>
*/
public Message(Address dest) {
setDest(dest);
headers=createHeaders(3);
}
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> then the message sent to the group.
* Otherwise, it contains a single destination and is sent to that member.<p>
* @param src Address of sender
* @param buf Message to be sent. Note that this buffer must not be modified (e.g. buf[0]=0 is
* not allowed), since we don't copy the contents on clopy() or clone().
*/
public Message(Address dest, Address src, byte[] buf) {
this(dest);
setSrc(src);
setBuffer(buf);
}
/**
* Constructs a message. The index and length parameters allow to provide a <em>reference</em> to
* a byte buffer, rather than a copy, and refer to a subset of the buffer. This is important when
* we want to avoid copying. When the message is serialized, only the subset is serialized.<br/>
* <em>
* Note that the byte[] buffer passed as argument must not be modified. Reason: if we retransmit the
* message, it would still have a ref to the original byte[] buffer passed in as argument, and so we would
* retransmit a changed byte[] buffer !
* </em>
* @param dest Address of receiver. If it is <em>null</em> then the message sent to the group.
* Otherwise, it contains a single destination and is sent to that member.<p>
* @param src Address of sender
* @param buf A reference to a byte buffer
* @param offset The index into the byte buffer
* @param length The number of bytes to be used from <tt>buf</tt>. Both index and length are checked for
* array index violations and an ArrayIndexOutOfBoundsException will be thrown if invalid
*/
public Message(Address dest, Address src, byte[] buf, int offset, int length) {
this(dest);
setSrc(src);
setBuffer(buf, offset, length);
}
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> then the message sent to the group.
* Otherwise, it contains a single destination and is sent to that member.<p>
* @param src Address of sender
* @param obj The object will be serialized into the byte buffer. <em>Object
* has to be serializable </em>! The resulting buffer must not be modified
* (e.g. buf[0]=0 is not allowed), since we don't copy the contents on clopy() or clone().<p/>
* Note that this is a convenience method and JGroups will use default Java serialization to
* serialize <code>obj</code> into a byte buffer.
*/
public Message(Address dest, Address src, Serializable obj) {
this(dest);
setSrc(src);
setObject(obj);
}
public Message() {
headers=createHeaders(3);
}
public Message(boolean create_headers) {
if(create_headers)
headers=createHeaders(3);
}
public Address getDest() {
return dest_addr;
}
public void setDest(Address new_dest) {
dest_addr=new_dest;
}
public Address getSrc() {
return src_addr;
}
public void setSrc(Address new_src) {
src_addr=new_src;
}
/**
* Returns a <em>reference</em> to the payload (byte buffer). Note that this buffer should not be modified as
* we do not copy the buffer on copy() or clone(): the buffer of the copied message is simply a reference to
* the old buffer.<br/>
* Even if offset and length are used: we return the <em>entire</em> buffer, not a subset.
*/
public byte[] getRawBuffer() {
return buf;
}
/**
* Returns a copy of the buffer if offset and length are used, otherwise a reference.
* @return byte array with a copy of the buffer.
*/
final public byte[] getBuffer() {
if(buf == null)
return null;
if(offset == 0 && length == buf.length)
return buf;
else {
byte[] retval=new byte[length];
System.arraycopy(buf, offset, retval, 0, length);
return retval;
}
}
final public void setBuffer(byte[] b) {
buf=b;
if(buf != null) {
offset=0;
length=buf.length;
}
else {
offset=length=0;
}
}
/**
* Set the internal buffer to point to a subset of a given buffer
* @param b The reference to a given buffer. If null, we'll reset the buffer to null
* @param offset The initial position
* @param length The number of bytes
*/
final public void setBuffer(byte[] b, int offset, int length) {
buf=b;
if(buf != null) {
if(offset < 0 || offset > buf.length)
throw new ArrayIndexOutOfBoundsException(offset);
if((offset + length) > buf.length)
throw new ArrayIndexOutOfBoundsException((offset+length));
this.offset=offset;
this.length=length;
}
else {
this.offset=this.length=0;
}
}
/**
<em>
* Note that the byte[] buffer passed as argument must not be modified. Reason: if we retransmit the
* message, it would still have a ref to the original byte[] buffer passed in as argument, and so we would
* retransmit a changed byte[] buffer !
* </em>
*/
public final void setBuffer(Buffer buf) {
if(buf != null) {
this.buf=buf.getBuf();
this.offset=buf.getOffset();
this.length=buf.getLength();
}
}
/** Returns the offset into the buffer at which the data starts */
public int getOffset() {
return offset;
}
/** Returns the number of bytes in the buffer */
public int getLength() {
return length;
}
/** Returns a reference to the headers hashmap, which is <em>immutable</em>. Any attempt to
* modify the returned map will cause a runtime exception */
public Map<String,Header> getHeaders() {
return headers.getHeaders();
}
public String printHeaders() {
return headers.printHeaders();
}
public int getNumHeaders() {
return headers.size();
}
/**
* Takes an object and uses Java serialization to generate the byte[] buffer which is set in the message.
*/
final public void setObject(Serializable obj) {
if(obj == null) return;
try {
byte[] tmp=Util.objectToByteBuffer(obj);
setBuffer(tmp);
}
catch(Exception ex) {
throw new IllegalArgumentException(ex);
}
}
/**
* Uses Java serialization to create an object from the buffer of the message. Note that this is dangerous when
* using your own classloader, e.g. inside of an application server ! Most likely, JGroups will use the system
* classloader to deserialize the buffer into an object, whereas (for example) a web application will want to
* use the webapp's classloader, resulting in a ClassCastException. The recommended way is for the application to
* use their own serialization and only pass byte[] buffer to JGroups.
* @return
*/
final public Object getObject() {
try {
return Util.objectFromByteBuffer(buf, offset, length);
}
catch(Exception ex) {
throw new IllegalArgumentException(ex);
}
}
public void setFlag(byte flag) {
if(flag > Byte.MAX_VALUE || flag < 0)
throw new IllegalArgumentException("flag has to be >= 0 and <= " + Byte.MAX_VALUE);
flags |= flag;
}
public void clearFlag(byte flag) {
if(flag > Byte.MAX_VALUE || flag < 0)
throw new IllegalArgumentException("flag has to be >= 0 and <= " + Byte.MAX_VALUE);
// if(isFlagSet(flag)) {
// flags ^= flag;
// }
flags &= ~flag;
}
public boolean isFlagSet(byte flag) {
return (flags & flag) == flag;
}
public byte getFlags() {
return flags;
}
/*---------------------- Used by protocol layers ----------------------*/
/** Puts a header given a key into the hashmap. Overwrites potential existing entry. */
public void putHeader(String key, Header hdr) {
headers.putHeader(key, hdr);
}
/**
* Puts a header given a key into the map, only if the key doesn't exist yet
* @param key
* @param hdr
* @return the previous value associated with the specified key, or
* <tt>null</tt> if there was no mapping for the key.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with the key,
* if the implementation supports null values.)
*/
public Header putHeaderIfAbsent(String key, Header hdr) {
return headers.putHeaderIfAbsent(key, hdr);
}
/**
*
* @param key
* @return the header assoaicted with key
* @deprecated Use getHeader() instead. The issue with removing a header is described in
* http://jira.jboss.com/jira/browse/JGRP-393
*/
public Header removeHeader(String key) {
return getHeader(key);
}
public Header getHeader(String key) {
return headers.getHeader(key);
}
/*---------------------------------------------------------------------*/
public Message copy() {
return copy(true);
}
/**
* Create a copy of the message. If offset and length are used (to refer to another buffer), the copy will
* contain only the subset offset and length point to, copying the subset into the new copy.
* @param copy_buffer
* @return Message with specified data
*/
public Message copy(boolean copy_buffer) {
Message retval=new Message(false);
retval.dest_addr=dest_addr;
retval.src_addr=src_addr;
retval.flags=flags;
if(copy_buffer && buf != null) {
// change bela Feb 26 2004: we don't resolve the reference
retval.setBuffer(buf, offset, length);
}
retval.headers=createHeaders(headers);
return retval;
}
protected Object clone() throws CloneNotSupportedException {
return copy();
}
public Message makeReply() {
return new Message(src_addr);
}
public String toString() {
StringBuilder ret=new StringBuilder(64);
ret.append("[dst: ");
if(dest_addr == null)
ret.append("<null>");
else
ret.append(dest_addr);
ret.append(", src: ");
if(src_addr == null)
ret.append("<null>");
else
ret.append(src_addr);
int size;
if((size=getNumHeaders()) > 0)
ret.append(" (").append(size).append(" headers)");
ret.append(", size=");
if(buf != null && length > 0)
ret.append(length);
else
ret.append('0');
ret.append(" bytes");
if(flags > 0)
ret.append(", flags=").append(flagsToString());
ret.append(']');
return ret.toString();
}
/** Tries to read an object from the message's buffer and prints it */
public String toStringAsObject() {
if(buf == null) return null;
try {
Object obj=getObject();
return obj != null ? obj.toString() : "";
}
catch(Exception e) { // it is not an object
return "";
}
}
/**
* Returns size of buffer, plus some constant overhead for src and dest, plus number of headers time
* some estimated size/header. The latter is needed because we don't want to marshal all headers just
* to find out their size requirements. If a header implements Sizeable, the we can get the correct
* size.<p> Size estimations don't have to be very accurate since this is mainly used by FRAG to
* determine whether to fragment a message or not. Fragmentation will then serialize the message,
* therefore getting the correct value.
*/
/**
* Returns the exact size of the marshalled message. Uses method size() of each header to compute the size, so if
* a Header subclass doesn't implement size() we will use an approximation. However, most relevant header subclasses
* have size() implemented correctly. (See org.jgroups.tests.SizeTest).
* @return The number of bytes for the marshalled message
*/
public long size() {
long retval=Global.BYTE_SIZE // leading byte
+ Global.BYTE_SIZE // flags
+ length // buffer
+ (buf != null? Global.INT_SIZE : 0); // if buf != null 4 bytes for length
// if(dest_addr != null)
// retval+=dest_addr.size();
if(src_addr != null)
retval+=(src_addr).size();
retval+=Global.SHORT_SIZE; // size (short)
retval+=headers.marshalledSize();
return retval;
}
public String printObjectHeaders() {
return headers.printObjectHeaders();
}
/* ----------------------------------- Interface Streamable ------------------------------- */
/**
* Streams all members (dest and src addresses, buffer and headers) to the output stream.
* @param out
* @throws IOException
*/
public void writeTo(DataOutputStream out) throws IOException {
byte leading=0;
if(src_addr != null) {
leading+=SRC_SET;
if(src_addr instanceof IpAddress) {
leading+=IPADDR_SRC;
if(((IpAddress)src_addr).getIpAddress() == null) {
leading+=SRC_HOST_NULL;
}
}
}
if(buf != null)
leading+=BUF_SET;
// 1. write the leading byte first
out.write(leading);
// the flags (e.g. OOB, LOW_PRIO)
out.write(flags);
// 3. src_addr
if(src_addr != null) {
if(src_addr instanceof IpAddress) {
src_addr.writeTo(out);
}
else {
Util.writeAddress(src_addr, out);
}
}
// 4. buf
if(buf != null) {
out.writeInt(length);
out.write(buf, offset, length);
}
// 5. headers
int size=headers.size();
out.writeShort(size);
final Object[] data=headers.getRawData();
for(int i=0; i < data.length; i+=2) {
if(data[i] != null) {
out.writeUTF((String)data[i]);
writeHeader((Header)data[i+1], out);
}
}
}
public void readFrom(DataInputStream in) throws IOException, IllegalAccessException, InstantiationException {
int len, leading;
String hdr_name;
Header hdr;
// 1. read the leading byte first
leading=in.readByte();
flags=in.readByte();
// 2. src_addr
if((leading & SRC_SET) == SRC_SET) {
if((leading & IPADDR_SRC) == IPADDR_SRC) {
src_addr=new IpAddress();
src_addr.readFrom(in);
}
else {
src_addr=Util.readAddress(in);
}
}
// 3. buf
if((leading & BUF_SET) == BUF_SET) {
len=in.readInt();
buf=new byte[len];
in.read(buf, 0, len);
length=len;
}
// 4. headers
len=in.readShort();
headers=createHeaders(len);
Object[] data=headers.getRawData();
int index=0;
for(int i=0; i < len; i++) {
hdr_name=in.readUTF();
data[index++]=hdr_name;
hdr=readHeader(in);
data[index++]=hdr;
// headers.putHeader(hdr_name, hdr);
}
}
/* --------------------------------- End of Interface Streamable ----------------------------- */
/* ----------------------------------- Private methods ------------------------------- */
private String flagsToString() {
StringBuilder sb=new StringBuilder();
boolean first=true;
if(isFlagSet(OOB)) {
first=false;
sb.append("OOB");
}
if(isFlagSet(LOW_PRIO)) {
if(!first)
sb.append("|");
else
first=false;
sb.append("LOW_PRIO");
}
if(isFlagSet(HIGH_PRIO)) {
if(!first)
sb.append("|");
else
first=false;
sb.append("HIGH_PRIO");
}
return sb.toString();
}
private static void writeHeader(Header value, DataOutputStream out) throws IOException {
short magic_number;
String classname;
ObjectOutputStream oos=null;
int size=value.size();
try {
magic_number=ClassConfigurator.getMagicNumber(value.getClass());
// write the magic number or the class name
out.writeShort(magic_number);
if(magic_number == -1) {
classname=value.getClass().getName();
out.writeUTF(classname);
if(log.isWarnEnabled())
log.warn("magic number for " + classname + " not found, make sure you add your header to " +
"jg-magic-map.xml, or register it programmatically with the ClassConfigurator");
}
out.writeShort(size);
// write the contents
if(value instanceof Streamable) {
((Streamable)value).writeTo(out);
}
else {
oos=new ObjectOutputStream(out);
value.writeExternal(oos);
if(!nonStreamableHeaders.contains(value.getClass())) {
nonStreamableHeaders.add(value.getClass());
if(log.isTraceEnabled())
log.trace("encountered non-Streamable header: " + value.getClass());
}
}
}
finally {
if(oos != null)
oos.close(); // this is a no-op on ByteArrayOutputStream
}
}
private static Header readHeader(DataInputStream in) throws IOException {
Header hdr;
short magic_number;
String classname;
Class clazz;
ObjectInputStream ois=null;
try {
magic_number=in.readShort();
if(magic_number != -1) {
clazz=ClassConfigurator.get(magic_number);
if(clazz == null)
throw new IllegalArgumentException("magic number " + magic_number + " is not available in magic map");
}
else {
classname=in.readUTF();
clazz=ClassConfigurator.get(classname);
}
in.readShort(); // we discard the size since we don't use it
hdr=(Header)clazz.newInstance();
if(hdr instanceof Streamable) {
((Streamable)hdr).readFrom(in);
}
else {
ois=new ObjectInputStream(in);
hdr.readExternal(ois);
}
}
catch(Exception ex) {
IOException io_ex=new IOException("failed reading header");
io_ex.initCause(ex);
throw io_ex;
}
return hdr;
}
private static Headers createHeaders(int size) {
return size > 0? new Headers(size) : new Headers(3);
}
private static Headers createHeaders(Headers m) {
return new Headers(m);
}
/* ------------------------------- End of Private methods ---------------------------- */
}