org.jgroups.protocols.relay.RELAY2 Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
package org.jgroups.protocols.relay;
import org.jgroups.*;
import org.jgroups.annotations.*;
import org.jgroups.conf.ConfiguratorFactory;
import org.jgroups.protocols.FORWARD_TO_COORD;
import org.jgroups.protocols.relay.config.RelayConfig;
import org.jgroups.stack.AddressGenerator;
import org.jgroups.stack.Protocol;
import org.jgroups.util.*;
import org.jgroups.util.UUID;
import org.w3c.dom.Node;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.InputStream;
import java.util.*;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
/**
*
* Design: ./doc/design/RELAY2.txt and at https://github.com/belaban/JGroups/blob/master/doc/design/RELAY2.txt.
* JIRA: https://issues.jboss.org/browse/JGRP-1433
* @author Bela Ban
* @since 3.2
*/
@XmlInclude(schema="relay.xsd",type=XmlInclude.Type.IMPORT,namespace="urn:jgroups:relay:1.0",alias="relay")
@XmlElement(name="RelayConfiguration",type="relay:RelayConfigurationType")
@MBean(description="RELAY2 protocol")
public class RELAY2 extends Protocol {
/* ------------------------------------------ Properties ---------------------------------------------- */
@Property(description="Name of the site (needs to be defined in the configuration)",writable=false)
protected String site;
@Property(description="Name of the relay configuration",writable=false)
protected String config;
@Property(description="Whether or not this node can become the site master. If false, " +
"and we become the coordinator, we won't start the bridge(s)",writable=false)
protected boolean can_become_site_master=true;
@Property(description="Maximum number of site masters. Setting this to a value greater than 1 means that we can " +
"have multiple site masters. If the value is greater than the number of cluster nodes, everyone in the site " +
"will be a site master (and thus join the global cluster",writable=false)
protected int max_site_masters=1;
@Property(description="Whether or not we generate our own addresses in which we use can_become_site_master. " +
"If this property is false, can_become_site_master is ignored")
protected boolean enable_address_tagging=false;
@Property(description="Whether or not to relay multicast (dest=null) messages")
protected boolean relay_multicasts=true;
@Property(description="If true, the creation of the relay channel (and the connect()) are done in the background. " +
"Async relay creation is recommended, so the view callback won't be blocked")
protected boolean async_relay_creation=true;
@Property(description="If true, logs a warning if the FORWARD_TO_COORD protocol is not found. This property might " +
"get deprecated soon")
protected boolean warn_when_ftc_missing=false;
/* --------------------------------------------- Fields ------------------------------------------------ */
/** A map containing site names (e.g. "LON") as keys and SiteConfigs as values */
protected final Map sites=new HashMap<>();
protected RelayConfig.SiteConfig site_config;
@ManagedAttribute(description="Whether this member is a site master")
protected volatile boolean is_site_master=false;
// A list of site masters in this (local) site
protected volatile List site_masters;
protected volatile Relayer relayer;
protected TimeScheduler timer;
protected volatile Address local_addr;
protected volatile List members=new ArrayList<>(11);
/** Whether or not FORWARD_TO_COORD is on the stack */
@ManagedAttribute(description="FORWARD_TO_COORD protocol is present below the current protocol")
protected boolean forwarding_protocol_present;
@Property(description="If true, a site master forwards messages received from other sites to randomly chosen " +
"members of the local site for load balancing, reducing work for itself")
protected boolean can_forward_local_cluster=false;
// protocol IDs above RELAY2
protected short[] prots_above;
protected volatile RouteStatusListener route_status_listener;
/** Number of messages forwarded to the local SiteMaster */
protected final AtomicLong forward_to_site_master=new AtomicLong(0);
protected final AtomicLong forward_sm_time=new AtomicLong(0);
/** Number of messages relayed by the local SiteMaster to a remote SiteMaster */
protected final AtomicLong relayed=new AtomicLong(0);
/** Total time spent relaying messages from the local SiteMaster to remote SiteMasters (in ns) */
protected final AtomicLong relayed_time=new AtomicLong(0);
/** Number of messages (received from a remote Sitemaster and) delivered by the local SiteMaster to a local node */
protected final AtomicLong forward_to_local_mbr=new AtomicLong(0);
protected final AtomicLong forward_to_local_mbr_time=new AtomicLong(0);
/** Number of messages delivered locally, e.g. received and delivered to self */
protected final AtomicLong local_deliveries=new AtomicLong(0);
/** Total time (ms) for received messages that are delivered locally */
protected final AtomicLong local_delivery_time=new AtomicLong(0);
// Fluent configuration
public RELAY2 site(String site_name) {site=site_name; return this;}
public RELAY2 config(String cfg) {config=cfg; return this;}
public RELAY2 canBecomeSiteMaster(boolean flag) {can_become_site_master=flag; return this;}
public RELAY2 enableAddressTagging(boolean flag) {enable_address_tagging=flag; return this;}
public RELAY2 relayMulticasts(boolean flag) {relay_multicasts=flag; return this;}
public RELAY2 asyncRelayCreation(boolean flag) {async_relay_creation=flag; return this;}
public String site() {return site;}
public List siteNames() {return getSites();}
public String config() {return config;}
public boolean canBecomeSiteMaster() {return can_become_site_master;}
public boolean enableAddressTagging() {return enable_address_tagging;}
public boolean relayMulticasts() {return relay_multicasts;}
public boolean asyncRelayCreation() {return async_relay_creation;}
public Address getLocalAddress() {return local_addr;}
public TimeScheduler getTimer() {return timer;}
public void incrementRelayed() {relayed.incrementAndGet();}
public void addToRelayedTime(long delta) {relayed_time.addAndGet(delta);}
public RouteStatusListener getRouteStatusListener() {return route_status_listener;}
public void setRouteStatusListener(RouteStatusListener l) {this.route_status_listener=l;}
@ManagedAttribute(description="Number of messages forwarded to the local SiteMaster")
public long getNumForwardedToSiteMaster() {return forward_to_site_master.get();}
@ManagedAttribute(description="The total time (in ms) spent forwarding messages to the local SiteMaster")
public long getTimeForwardingToSM() {return TimeUnit.MILLISECONDS.convert(forward_sm_time.get(),TimeUnit.NANOSECONDS);}
@ManagedAttribute(description="The average number of messages / s for forwarding messages to the local SiteMaster")
public long getAvgMsgsForwardingToSM() {return getTimeForwardingToSM() > 0?
(long)(getNumForwardedToSiteMaster() / (getTimeForwardingToSM()/1000.0)) : 0;}
@ManagedAttribute(description="Number of messages sent by this SiteMaster to a remote SiteMaster")
public long getNumRelayed() {return relayed.get();}
@ManagedAttribute(description="The total time (ms) spent relaying messages from this SiteMaster to remote SiteMasters")
public long getTimeRelaying() {return TimeUnit.MILLISECONDS.convert(relayed_time.get(), TimeUnit.NANOSECONDS);}
@ManagedAttribute(description="The average number of messages / s for relaying messages from this SiteMaster to remote SiteMasters")
public long getAvgMsgsRelaying() {return getTimeRelaying() > 0? (long)(getNumRelayed() / (getTimeRelaying()/1000.0)) : 0;}
@ManagedAttribute(description="Number of messages (received from a remote Sitemaster and) delivered " +
"by this SiteMaster to a local node")
public long getNumForwardedToLocalMbr() {return forward_to_local_mbr.get();}
@ManagedAttribute(description="The total time (in ms) spent forwarding messages to a member in the same site")
public long getTimeForwardingToLocalMbr() {return TimeUnit.MILLISECONDS.convert(forward_to_local_mbr_time.get(),TimeUnit.NANOSECONDS);}
@ManagedAttribute(description="The average number of messages / s for forwarding messages to a member in the same site")
public long getAvgMsgsForwardingToLocalMbr() {return getTimeForwardingToLocalMbr() > 0?
(long)(getNumForwardedToLocalMbr() / (getTimeForwardingToLocalMbr()/1000.0)) : 0;}
@ManagedAttribute(description="Number of messages delivered locally, e.g. received and delivered to self")
public long getNumLocalDeliveries() {return local_deliveries.get();}
@ManagedAttribute(description="The total time (ms) spent delivering received messages locally")
public long getTimeDeliveringLocally() {return TimeUnit.MILLISECONDS.convert(local_delivery_time.get(),TimeUnit.NANOSECONDS);}
@ManagedAttribute(description="The average number of messages / s for delivering received messages locally")
public long getAvgMsgsDeliveringLocally() {return getTimeDeliveringLocally() > 0?
(long)(getNumLocalDeliveries() / (getTimeDeliveringLocally()/1000.0)) : 0;}
@ManagedAttribute(description="Whether or not this instance is a site master")
public boolean isSiteMaster() {return relayer != null;}
public void resetStats() {
super.resetStats();
forward_to_site_master.set(0);
forward_sm_time.set(0);
relayed.set(0);
relayed_time.set(0);
forward_to_local_mbr.set(0);
forward_to_local_mbr_time.set(0);
local_deliveries.set(0);
local_delivery_time.set(0);
}
public View getBridgeView(String cluster_name) {
Relayer tmp=relayer;
return tmp != null? tmp.getBridgeView(cluster_name) : null;
}
public RELAY2 addSite(String site_name, RelayConfig.SiteConfig cfg) {
sites.put(site_name,cfg);
return this;
}
public List getSites() {
return sites.isEmpty()? Collections.emptyList() : new ArrayList<>(sites.keySet());
}
public void init() throws Exception {
super.init();
configure();
}
public void configure() throws Exception {
timer=getTransport().getTimer();
if(site == null)
throw new IllegalArgumentException("site cannot be null");
if(max_site_masters < 1) {
log.warn("max_size_masters was " + max_site_masters + ", changed to 1");
max_site_masters=1;
}
if(config != null)
parseSiteConfiguration(sites);
site_config=sites.get(site);
if(site_config == null)
throw new Exception("site configuration for \"" + site + "\" not found in " + config);
log.trace(local_addr + ": site configuration:\n" + site_config);
if(!site_config.getForwards().isEmpty())
log.warn(local_addr + ": forwarding routes are currently not supported and will be ignored. This will change " +
"with hierarchical routing (https://issues.jboss.org/browse/JGRP-1506)");
List available_down_services=getDownServices();
forwarding_protocol_present=available_down_services != null && available_down_services.contains(Event.FORWARD_TO_COORD);
if(!forwarding_protocol_present && warn_when_ftc_missing && log.isWarnEnabled())
log.warn(local_addr + ": " + FORWARD_TO_COORD.class.getSimpleName() + " protocol not found below; " +
"unable to re-submit messages to the new coordinator if the current coordinator crashes");
if(enable_address_tagging) {
JChannel ch=getProtocolStack().getChannel();
ch.addAddressGenerator(new AddressGenerator() {
public Address generateAddress() {
ExtendedUUID retval=ExtendedUUID.randomUUID();
if(can_become_site_master)
retval.setFlag(ExtendedUUID.can_become_site_master);
return retval;
}
});
}
prots_above=getIdsAbove();
}
public void stop() {
super.stop();
is_site_master=false;
log.trace(local_addr + ": ceased to be site master; closing bridges");
if(relayer != null)
relayer.stop();
}
/**
* Parses the configuration by reading the config file.
* @throws Exception
*/
protected void parseSiteConfiguration(final Map map) throws Exception {
InputStream input=null;
try {
input=ConfiguratorFactory.getConfigStream(config);
RelayConfig.parse(input, map);
}
finally {
Util.close(input);
}
}
public void parse(Node node) throws Exception {
RelayConfig.parse(node, sites);
}
@ManagedOperation(description="Prints the contents of the routing table. " +
"Only available if we're the current coordinator (site master)")
public String printRoutes() {
return relayer != null? relayer.printRoutes() : "n/a (not site master)";
}
/**
* Returns the bridge channel to a given site
* @param site_name The site name, e.g. "SFO"
* @return The JChannel to the given site, or null if no route was found or we're not the coordinator
*/
public JChannel getBridge(String site_name) {
Relayer tmp=relayer;
Relayer.Route route=tmp != null? tmp.getRoute(site_name): null;
return route != null? route.bridge() : null;
}
/**
* Returns the route to a given site
* @param site_name The site name, e.g. "SFO"
* @return The route to the given site, or null if no route was found or we're not the coordinator
*/
public Relayer.Route getRoute(String site_name) {
Relayer tmp=relayer;
return tmp != null? tmp.getRoute(site_name): null;
}
public Object down(Event evt) {
switch(evt.getType()) {
case Event.MSG:
Message msg=(Message)evt.getArg();
Address dest=msg.getDest();
if(dest == null || !(dest instanceof SiteAddress))
break;
SiteAddress target=(SiteAddress)dest;
Address src=msg.getSrc();
SiteAddress sender=src instanceof SiteMaster? new SiteMaster(((SiteMaster)src).getSite())
: new SiteUUID((UUID)local_addr, UUID.get(local_addr), site);
if(local_addr instanceof ExtendedUUID)
((ExtendedUUID)sender).addContents((ExtendedUUID)local_addr);
// target is in the same site; we can deliver the message in our local cluster
if(target.getSite().equals(site)) {
if(local_addr.equals(target) || (target instanceof SiteMaster && is_site_master)) {
// we cannot simply pass msg down, as the transport doesn't know how to send a message to a (e.g.) SiteMaster
long start=stats? System.nanoTime() : 0;
forwardTo(local_addr, target, sender, msg, false);
if(stats) {
local_delivery_time.addAndGet(System.nanoTime() - start);
local_deliveries.incrementAndGet();
}
}
else
deliverLocally(target, sender, msg);
return null;
}
// forward to the coordinator unless we're the coord (then route the message directly)
if(!is_site_master) {
long start=stats? System.nanoTime() : 0;
Address site_master=pickSiteMaster();
if(site_master == null)
throw new IllegalStateException("site master is null");
forwardTo(site_master, target, sender, msg, max_site_masters == 1);
if(stats) {
forward_sm_time.addAndGet(System.nanoTime() - start);
forward_to_site_master.incrementAndGet();
}
}
else
route(target, sender, msg);
return null;
case Event.SET_LOCAL_ADDRESS:
local_addr=(Address)evt.getArg();
break;
case Event.VIEW_CHANGE:
handleView((View)evt.getArg());
break;
}
return down_prot.down(evt);
}
public Object up(Event evt) {
switch(evt.getType()) {
case Event.MSG:
Message msg=(Message)evt.getArg();
Relay2Header hdr=(Relay2Header)msg.getHeader(id);
Address dest=msg.getDest();
if(hdr == null) {
// forward a multicast message to all bridges except myself, then pass up
if(dest == null && is_site_master && relay_multicasts && !msg.isFlagSet(Message.Flag.NO_RELAY)) {
Address src=msg.getSrc();
Address sender=new SiteUUID((UUID)msg.getSrc(), UUID.get(msg.getSrc()), site);
if(src instanceof ExtendedUUID)
((SiteUUID)sender).addContents((ExtendedUUID)src);
sendToBridges(sender, msg, site);
}
break; // pass up
}
else { // header is not null
if(dest != null)
handleMessage(hdr, msg);
else
deliver(null, hdr.original_sender, msg);
}
return null;
case Event.VIEW_CHANGE:
handleView((View)evt.getArg());
break;
}
return up_prot.up(evt);
}
public void up(MessageBatch batch) {
for(Message msg: batch) {
Relay2Header hdr=(Relay2Header)msg.getHeader(id);
Address dest=msg.getDest();
if(hdr == null) {
// forward a multicast message to all bridges except myself, then pass up
if(dest == null && is_site_master && relay_multicasts && !msg.isFlagSet(Message.Flag.NO_RELAY)) {
Address src=msg.getSrc();
Address sender=new SiteUUID((UUID)msg.getSrc(), UUID.get(msg.getSrc()), site);
if(src instanceof ExtendedUUID)
((SiteUUID)sender).addContents((ExtendedUUID)src);
sendToBridges(sender, msg, site);
}
}
else { // header is not null
batch.remove(msg); // message is consumed
if(dest != null)
handleMessage(hdr, msg);
else
deliver(null, hdr.original_sender, msg);
}
}
if(!batch.isEmpty())
up_prot.up(batch);
}
/** Called to handle a message received by the relayer */
protected void handleRelayMessage(Relay2Header hdr, Message msg) {
if(hdr.final_dest != null) {
Message message=msg;
Relay2Header header=hdr;
if(header.type == Relay2Header.DATA && can_forward_local_cluster) {
SiteUUID site_uuid=(SiteUUID)hdr.final_dest;
// If configured to do so, we want to load-balance these messages,
int index=(int)Util.random( members.size()) -1;
UUID tmp=(UUID)members.get(index);
SiteAddress final_dest=new SiteUUID(tmp, site_uuid.getName(), site_uuid.getSite());
// If we select a different address to handle this message, we handle it here.
if(!final_dest.equals(hdr.final_dest)) {
message=copy(msg);
header=new Relay2Header(Relay2Header.DATA, final_dest, hdr.original_sender );
message.putHeader(id, header);
}
}
handleMessage(header, message);
}
else {
Message copy=copy(msg).dest(null).src(null).putHeader(id, hdr);
down_prot.down(new Event(Event.MSG, copy)); // multicast locally
// Don't forward: https://issues.jboss.org/browse/JGRP-1519
// sendToBridges(msg.getSrc(), buf, from_site, site_id); // forward to all bridges except self and from
}
}
/** Called to handle a message received by the transport */
protected void handleMessage(Relay2Header hdr, Message msg) {
switch(hdr.type) {
case Relay2Header.DATA:
route((SiteAddress)hdr.final_dest, (SiteAddress)hdr.original_sender, msg);
break;
case Relay2Header.SITE_UNREACHABLE:
up_prot.up(new Event(Event.SITE_UNREACHABLE, hdr.final_dest));
break;
case Relay2Header.HOST_UNREACHABLE:
break;
default:
log.error("type " + hdr.type + " unknown");
break;
}
}
/**
* Routes the message to the target destination, used by a site master (coordinator)
* @param dest
* @param sender the address of the sender
* @param msg The message
*/
protected void route(SiteAddress dest, SiteAddress sender, Message msg) {
String target_site=dest.getSite();
if(target_site.equals(site)) {
if(local_addr.equals(dest) || ((dest instanceof SiteMaster) && is_site_master)) {
deliver(dest, sender, msg);
}
else
deliverLocally(dest, sender, msg); // send to member in same local site
return;
}
Relayer tmp=relayer;
if(tmp == null) {
log.warn(local_addr + ": not site master; dropping message");
return;
}
Relayer.Route route=tmp.getRoute(target_site);
if(route == null) {
log.error(local_addr + ": no route to " + target_site + ": dropping message");
sendSiteUnreachableTo(sender, target_site);
}
else {
route.send(dest,sender,msg);
}
}
/** Sends the message via all bridges excluding the excluded_sites bridges */
protected void sendToBridges(Address sender, final Message msg, String ... excluded_sites) {
Relayer tmp=relayer;
List routes=tmp != null? tmp.getRoutes(excluded_sites) : null;
if(routes == null)
return;
for(Relayer.Route route: routes) {
if(log.isTraceEnabled())
log.trace(local_addr + ": relaying multicast message from " + sender + " via route " + route);
try {
route.send(null, sender, msg);
}
catch(Exception ex) {
log.error(local_addr + ": failed relaying message from " + sender + " via route " + route, ex);
}
}
}
/**
* Sends a SITE-UNREACHABLE message to the sender of the message. Because the sender is always local (we're the
* relayer), no routing needs to be done
* @param dest
* @param target_site
*/
protected void sendSiteUnreachableTo(Address dest, String target_site) {
Message msg=new Message(dest).setFlag(Message.Flag.OOB, Message.Flag.INTERNAL)
.src(new SiteUUID((UUID)local_addr, UUID.get(local_addr), site))
.putHeader(id,new Relay2Header(Relay2Header.SITE_UNREACHABLE,new SiteMaster(target_site),null));
down_prot.down(new Event(Event.MSG, msg));
}
protected void forwardTo(Address next_dest, SiteAddress final_dest, Address original_sender, final Message msg,
boolean forward_to_current_coord) {
if(log.isTraceEnabled())
log.trace(local_addr + ": forwarding message to final destination " + final_dest + " to " +
(forward_to_current_coord? " the current coordinator" : next_dest));
Message copy=copy(msg).dest(next_dest).src(null);
Relay2Header hdr=new Relay2Header(Relay2Header.DATA, final_dest, original_sender);
copy.putHeader(id,hdr);
if(forward_to_current_coord && forwarding_protocol_present)
down_prot.down(new Event(Event.FORWARD_TO_COORD, copy));
else
down_prot.down(new Event(Event.MSG, copy));
}
protected void deliverLocally(SiteAddress dest, SiteAddress sender, Message msg) {
Address local_dest;
boolean send_to_coord=false;
if(dest instanceof SiteUUID) {
if(dest instanceof SiteMaster) {
local_dest=pickSiteMaster();
if(local_dest == null)
throw new IllegalStateException("site master was null");
send_to_coord=true;
}
else {
SiteUUID tmp=(SiteUUID)dest;
local_dest=new UUID(tmp.getMostSignificantBits(), tmp.getLeastSignificantBits());
}
}
else
local_dest=dest;
if(log.isTraceEnabled())
log.trace(local_addr + ": delivering message to " + dest + " in local cluster");
long start=stats? System.nanoTime() : 0;
forwardTo(local_dest, dest, sender, msg, send_to_coord);
if(stats) {
forward_to_local_mbr_time.addAndGet(System.nanoTime() - start);
forward_to_local_mbr.incrementAndGet();
}
}
protected void deliver(Address dest, Address sender, final Message msg) {
try {
Message copy=copy(msg).dest(dest).src(sender);
if(log.isTraceEnabled())
log.trace(local_addr + ": delivering message from " + sender);
long start=stats? System.nanoTime() : 0;
up_prot.up(new Event(Event.MSG, copy));
if(stats) {
local_delivery_time.addAndGet(System.nanoTime() - start);
local_deliveries.incrementAndGet();
}
}
catch(Exception e) {
log.error("failed delivering message", e);
}
}
/** Copies the message, but only the headers above the current protocol (RELAY) (or RpcDispatcher related headers) */
protected Message copy(Message msg) {
return msg.copy(true, Global.BLOCKS_START_ID, this.prots_above);
}
public void handleView(View view) {
members=view.getMembers(); // First, save the members for routing received messages to local members
List old_site_masters=site_masters;
List new_site_masters=determineSiteMasters(view);
boolean become_site_master=new_site_masters.contains(local_addr)
&& (old_site_masters == null || !old_site_masters.contains(local_addr));
boolean cease_site_master=old_site_masters != null
&& old_site_masters.contains(local_addr) && !new_site_masters.contains(local_addr);
site_masters=new_site_masters;
if(become_site_master) {
is_site_master=true;
final String bridge_name="_" + UUID.get(local_addr);
if(relayer != null)
relayer.stop();
relayer=new Relayer(this, log);
final Relayer tmp=relayer;
if(async_relay_creation) {
timer.execute(new Runnable() {
public void run() {
startRelayer(tmp, bridge_name);
}
});
}
else
startRelayer(relayer, bridge_name);
}
else {
if(cease_site_master) { // ceased being the site master: stop the relayer
is_site_master=false;
log.trace(local_addr + ": ceased to be site master; closing bridges");
if(relayer != null)
relayer.stop();
}
}
}
protected void startRelayer(Relayer rel, String bridge_name) {
try {
log.trace(local_addr + ": became site master; starting bridges");
rel.start(site_config.getBridges(), bridge_name, site);
}
catch(Throwable t) {
log.error(local_addr + ": failed starting relayer", t);
}
}
/**
* Iterates over the list of members and adds every member if the member's rank is below max_site_masters. Skips
* members which cannot become site masters (can_become_site_master == false). If no site master can be found,
* the first member of the view will be returned (even if it has can_become_site_master == false)
*/
protected List determineSiteMasters(View view) {
List retval=new ArrayList<>(view.size());
int selected=0;
for(Address member: view) {
if(member instanceof ExtendedUUID && !((ExtendedUUID)member).isFlagSet(ExtendedUUID.can_become_site_master))
continue;
if(selected++ < max_site_masters)
retval.add(member);
}
if(retval.isEmpty()) {
Address tmp=Util.getCoordinator(view);
if(tmp != null)
retval.add(Util.getCoordinator(view));
}
return retval;
}
/** Returns a random site master from site_masters */
protected Address pickSiteMaster() {
return Util.pickRandomElement(site_masters);
}
public static class Relay2Header extends Header {
public static final byte DATA = 1;
public static final byte SITE_UNREACHABLE = 2; // final_dest is a SiteMaster
public static final byte HOST_UNREACHABLE = 3; // final_dest is a SiteUUID (not currently used)
protected byte type;
protected Address final_dest;
protected Address original_sender;
public Relay2Header() {
}
public Relay2Header(byte type, Address final_dest, Address original_sender) {
this.type=type;
this.final_dest=final_dest;
this.original_sender=original_sender;
}
public int size() {
return Global.BYTE_SIZE + Util.size(final_dest) + Util.size(original_sender);
}
public void writeTo(DataOutput out) throws Exception {
out.writeByte(type);
Util.writeAddress(final_dest, out);
Util.writeAddress(original_sender, out);
}
public void readFrom(DataInput in) throws Exception {
type=in.readByte();
final_dest=Util.readAddress(in);
original_sender=Util.readAddress(in);
}
public String toString() {
return typeToString(type) + " [dest=" + final_dest + ", sender=" + original_sender + "]";
}
protected static String typeToString(byte type) {
switch(type) {
case DATA: return "DATA";
case SITE_UNREACHABLE: return "SITE_UNREACHABLE";
case HOST_UNREACHABLE: return "HOST_UNREACHABLE";
default: return "";
}
}
}
}