// $Id: Message.java,v 1.53 2006/08/13 15:38:52 belaban Exp $
package org.jgroups;
import EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap;
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.Marshaller;
import org.jgroups.util.Streamable;
import org.jgroups.util.Util;
import java.io.*;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
/**
* 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
*/
public class Message implements Externalizable, 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 transient int offset=0;
/** The number of bytes in the buffer (usually buf.length is buf not equal to null). */
protected transient int length=0;
/** Map<String,Header> */
protected Map headers;
protected static final Log log=LogFactory.getLog(Message.class);
private static final long serialVersionUID=7966206671974139740L;
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;
static final HashSet nonStreamableHeaders=new HashSet(); // todo: remove when all headers are streamable
/** Map<Address,Address>. Maintains mappings to canonical addresses */
private static final Map canonicalAddresses=new ConcurrentReaderHashMap();
private static final boolean DISABLE_CANONICALIZATION;
static {
boolean b;
try {
b=Boolean.getBoolean("disable_canonicalization");
}
catch (java.security.AccessControlException e) {
// this will happen in an applet context
b=false;
}
DISABLE_CANONICALIZATION=b;
}
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> or a <em>string</em>, then
* it is sent to the group (either to current group or to the group as given
* in the string). If it is a Vector, then it contains a number of addresses
* to which it must be sent. Otherwise, it contains a single destination.<p>
* Addresses are generally untyped (all are of type <em>Object</em>. A channel
* instance must know what types of addresses it expects and downcast
* accordingly.
*/
public Message(Address dest) {
dest_addr=dest;
headers=createHeaders(7);
}
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> or a <em>string</em>, then
* it is sent to the group (either to current group or to the group as given
* in the string). If it is a Vector, then it contains a number of addresses
* to which it must be sent. Otherwise, it contains a single destination.<p>
* Addresses are generally untyped (all are of type <em>Object</em>. A channel
* instance must know what types of addresses it expects and downcast
* accordingly.
* @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);
src_addr=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.
* @param dest Address of receiver. If it is <em>null</em> or a <em>string</em>, then
* it is sent to the group (either to current group or to the group as given
* in the string). If it is a Vector, then it contains a number of addresses
* to which it must be sent. Otherwise, it contains a single destination.<p>
* Addresses are generally untyped (all are of type <em>Object</em>. A channel
* instance must know what types of addresses it expects and downcast
* accordingly.
* @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);
src_addr=src;
setBuffer(buf, offset, length);
}
/** Public constructor
* @param dest Address of receiver. If it is <em>null</em> or a <em>string</em>, then
* it is sent to the group (either to current group or to the group as given
* in the string). If it is a Vector, then it contains a number of addresses
* to which it must be sent. Otherwise, it contains a single destination.<p>
* Addresses are generally untyped (all are of type <em>Object</em>. A channel
* instance must know what types of addresses it expects and downcast
* accordingly.
* @param src Address of sender
* @param obj The object will be serialized into the byte buffer. <em>Object
* has to be serializable </em>! Note that 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().
*/
public Message(Address dest, Address src, Serializable obj) {
this(dest);
src_addr=src;
setObject(obj);
}
public Message() {
headers=createHeaders(7);
}
public Message(boolean create_headers) {
if(create_headers)
headers=createHeaders(7);
}
public Address getDest() {
return dest_addr;
}
public void setDest(Address new_dest) {
if(DISABLE_CANONICALIZATION)
dest_addr=new_dest;
else
dest_addr=canonicalAddress(new_dest);
}
public Address getSrc() {
return src_addr;
}
public void setSrc(Address new_src) {
if(DISABLE_CANONICALIZATION)
src_addr=new_src;
else
src_addr=canonicalAddress(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 {
offset=length=0;
}
}
/** 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;
}
public Map getHeaders() {
return headers;
}
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.toString());
}
}
final public Object getObject() {
// if(buf == null) return null;
try {
return Util.objectFromByteBuffer(buf, offset, length);
}
catch(Exception ex) {
throw new IllegalArgumentException(ex.toString());
}
}
/**
* Nulls all fields of this message so that the message can be reused. Removes all headers from the
* hashmap, but keeps the hashmap
*/
public void reset() {
dest_addr=src_addr=null;
setBuffer(null);
headers.clear();
}
/*---------------------- 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.put(key, hdr);
}
public Header removeHeader(String key) {
return (Header)headers.remove(key);
}
public void removeHeaders() {
headers.clear();
}
public Header getHeader(String key) {
return (Header)headers.get(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;
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() {
StringBuffer ret=new StringBuffer(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(headers != null && (size=headers.size()) > 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");
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
+ 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();
Map.Entry entry;
String key;
Header hdr;
retval+=Global.SHORT_SIZE; // size (short)
for(Iterator it=headers.entrySet().iterator(); it.hasNext();) {
entry=(Map.Entry)it.next();
key=(String)entry.getKey();
retval+=key.length() +2; // not the same as writeUTF(), but almost
hdr=(Header)entry.getValue();
retval+=5; // 1 for presence of magic number, 4 for magic number
retval+=hdr.size();
}
return retval;
}
public String printObjectHeaders() {
StringBuffer sb=new StringBuffer();
Map.Entry entry;
if(headers != null) {
for(Iterator it=headers.entrySet().iterator(); it.hasNext();) {
entry=(Map.Entry)it.next();
sb.append(entry.getKey()).append(": ").append(entry.getValue()).append('\n');
}
}
return sb.toString();
}
/* ----------------------------------- Interface Externalizable ------------------------------- */
public void writeExternal(ObjectOutput out) throws IOException {
int len;
Externalizable hdr;
Map.Entry entry;
if(dest_addr != null) {
out.writeBoolean(true);
Marshaller.write(dest_addr, out);
}
else {
out.writeBoolean(false);
}
if(src_addr != null) {
out.writeBoolean(true);
Marshaller.write(src_addr, out);
}
else {
out.writeBoolean(false);
}
if(buf == null)
out.writeInt(0);
else {
out.writeInt(length);
out.write(buf, offset, length);
}
len=headers.size();
out.writeInt(len);
for(Iterator it=headers.entrySet().iterator(); it.hasNext();) {
entry=(Map.Entry)it.next();
out.writeUTF((String)entry.getKey());
hdr=(Externalizable)entry.getValue();
Marshaller.write(hdr, out);
}
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
boolean destAddressExist=in.readBoolean();
if(destAddressExist) {
dest_addr=(Address)Marshaller.read(in);
if(!DISABLE_CANONICALIZATION)
dest_addr=canonicalAddress(dest_addr);
}
boolean srcAddressExist=in.readBoolean();
if(srcAddressExist) {
src_addr=(Address)Marshaller.read(in);
if(!DISABLE_CANONICALIZATION)
src_addr=canonicalAddress(src_addr);
}
int i=in.readInt();
if(i != 0) {
buf=new byte[i];
in.readFully(buf);
offset=0;
length=buf.length;
}
int len=in.readInt();
while(len-- > 0) {
Object key=in.readUTF();
Object value=Marshaller.read(in);
headers.put(key, value);
}
}
/* --------------------------------- End of Interface Externalizable ----------------------------- */
/* ----------------------------------- 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(dest_addr != null) {
// leading+=DEST_SET;
// if(dest_addr instanceof IpAddress)
// leading+=IPADDR_DEST;
// }
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);
// 2. dest_addr
// if(dest_addr != null) {
// if(dest_addr instanceof IpAddress)
// dest_addr.writeTo(out);
// else
// Util.writeAddress(dest_addr, out);
// }
// 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);
Map.Entry entry;
for(Iterator it=headers.entrySet().iterator(); it.hasNext();) {
entry=(Map.Entry)it.next();
out.writeUTF((String)entry.getKey());
writeHeader((Header)entry.getValue(), 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();
// 1. dest_addr
// if((leading & DEST_SET) == DEST_SET) {
// if((leading & IPADDR_DEST) == IPADDR_DEST) {
// dest_addr=new IpAddress();
// dest_addr.readFrom(in);
// }
// else {
// dest_addr=Util.readAddress(in);
// }
// }
// 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);
}
if(!DISABLE_CANONICALIZATION)
src_addr=canonicalAddress(src_addr);
}
// 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);
for(int i=0; i < len; i++) {
hdr_name=in.readUTF();
hdr=readHeader(in);
headers.put(hdr_name, hdr);
}
}
/* --------------------------------- End of Interface Streamable ----------------------------- */
/* ----------------------------------- Private methods ------------------------------- */
private static void writeHeader(Header value, DataOutputStream out) throws IOException {
int magic_number;
String classname;
ObjectOutputStream oos=null;
try {
magic_number=ClassConfigurator.getInstance(false).getMagicNumber(value.getClass());
// write the magic number or the class name
if(magic_number == -1) {
out.writeBoolean(false);
classname=value.getClass().getName();
out.writeUTF(classname);
}
else {
out.writeBoolean(true);
out.writeInt(magic_number);
}
// 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());
}
}
}
catch(ChannelException e) {
IOException io_ex=new IOException("failed writing header");
io_ex.initCause(e);
throw io_ex;
}
finally {
if(oos != null)
oos.close(); // this is a no-op on ByteArrayOutputStream
}
}
private static Header readHeader(DataInputStream in) throws IOException {
Header hdr;
boolean use_magic_number=in.readBoolean();
int magic_number;
String classname;
Class clazz;
ObjectInputStream ois=null;
try {
if(use_magic_number) {
magic_number=in.readInt();
clazz=ClassConfigurator.getInstance(false).get(magic_number);
if(clazz == null)
log.error("magic number " + magic_number + " is not available in magic map");
}
else {
classname=in.readUTF();
clazz=ClassConfigurator.getInstance(false).get(classname);
}
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 Map createHeaders(int size) {
return size > 0? new ConcurrentReaderHashMap(size) : new ConcurrentReaderHashMap();
}
private static Map createHeaders(Map m) {
return new ConcurrentReaderHashMap(m);
}
/** canonicalize addresses to some extent. There are race conditions
* allowed in this method, so it may not fully canonicalize an address
* @param nonCanonicalAddress
* @return canonical representation of the address
*/
private static Address canonicalAddress(Address nonCanonicalAddress) {
Address result=null;
if(nonCanonicalAddress == null) {
return null;
}
// do not synchronize between get/put on the canonical map to avoid cost of contention
// this can allow multiple equivalent addresses to leak out, but it's worth the cost savings
try {
result=(Address)canonicalAddresses.get(nonCanonicalAddress);
}
catch(NullPointerException npe) {
// no action needed
}
if(result == null) {
result=nonCanonicalAddress;
canonicalAddresses.put(nonCanonicalAddress, result);
}
return result;
}
/* ------------------------------- End of Private methods ---------------------------- */
}