org.jgroups.protocols.FILE_PING 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;
import org.jgroups.Address;
import org.jgroups.Event;
import org.jgroups.PhysicalAddress;
import org.jgroups.View;
import org.jgroups.annotations.ManagedAttribute;
import org.jgroups.annotations.ManagedOperation;
import org.jgroups.annotations.Property;
import org.jgroups.util.NameCache;
import org.jgroups.util.Responses;
import org.jgroups.util.TimeScheduler;
import org.jgroups.util.Util;
import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Future;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
/**
* Simple discovery protocol which uses a file on shared storage such as an SMB share, NFS mount or S3. The local
* address information, e.g. UUID and physical addresses mappings are written to the file and the content is read and
* added to our transport's UUID-PhysicalAddress cache.
* The design is at doc/design/FILE_PING.txt
* @author Bela Ban
*/
public class FILE_PING extends Discovery {
protected static final String SUFFIX=".list";
protected static final Pattern regexp=Pattern.compile("[\0<>:\"/\\|?*]");
/* ----------------------------------------- Properties -------------------------------------------------- */
@Property(description="The absolute path of the shared file")
protected String location=File.separator + "tmp" + File.separator + "jgroups";
@Property(description="If true, on a view change, the new coordinator removes files from old coordinators")
protected boolean remove_old_coords_on_view_change;
@Property(description="If true, on a view change, the new coordinator removes all data except its own")
protected boolean remove_all_data_on_view_change;
@Property(description="The max number of times my own information should be written to the storage after a view change")
protected int info_writer_max_writes_after_view=2;
@Property(description="Interval (in ms) at which the info writer should kick in")
protected long info_writer_sleep_time=10000;
@Property(description="When a non-initial discovery is run, and InfoWriter is not running, write the data to " +
"disk (if true). JIRA: https://issues.jboss.org/browse/JGRP-2288")
protected boolean write_data_on_find;
@Property(description = "If set, a shutdown hook is registered with the JVM to remove the local address "
+ "from the store. Default is true", writable = false)
protected boolean register_shutdown_hook = true;
@Property(description="Change the backend store when the view changes. If off, then the file is only changed on " +
"joins, but not on leaves. Enabling this will increase traffic to the backend store.")
protected boolean update_store_on_view_change=true;
@ManagedAttribute(description="Number of writes to the file system or cloud store")
protected int writes;
@ManagedAttribute(description="Number of reads from the file system or cloud store")
protected int reads;
/* --------------------------------------------- Fields ------------------------------------------------------ */
protected File root_dir=null;
protected static final FilenameFilter filter=(dir, name1) -> name1.endsWith(SUFFIX);
protected Future info_writer;
public boolean isDynamic() {return true;}
public String getLocation() {return location;}
public FILE_PING setLocation(String l) {this.location=l; return this;}
public boolean getRemoveAllDataOnViewChange() {return remove_all_data_on_view_change;}
public FILE_PING setRemoveAllDataOnViewChange(boolean r) {remove_all_data_on_view_change=r; return this;}
@ManagedAttribute(description="Whether the InfoWriter task is running")
public synchronized boolean isInfoWriterRunning() {return info_writer != null && !info_writer.isDone();}
@ManagedOperation(description="Causes the member to write its own information into the DB, replacing an existing entry")
public void writeInfo() {if(is_coord) writeAll();}
public void init() throws Exception {
super.init();
createRootDir();
if(register_shutdown_hook) {
Runtime.getRuntime().addShutdownHook(new Thread(() -> remove(cluster_name, local_addr)));
}
}
public void stop() {
super.stop();
stopInfoWriter();
remove(cluster_name, local_addr);
}
public void resetStats() {
super.resetStats();
reads=writes=0;
}
public Object down(Event evt) {
switch(evt.getType()) {
case Event.VIEW_CHANGE:
View old_view=view;
boolean previous_coord=is_coord;
Object retval=super.down(evt);
View new_view=evt.getArg();
handleView(new_view, old_view, previous_coord != is_coord);
return retval;
}
return super.down(evt);
}
public void findMembers(final List members, final boolean initial_discovery, Responses responses) {
try {
readAll(members, cluster_name, responses);
if(responses.isEmpty()) {
PhysicalAddress physical_addr=(PhysicalAddress)down(new Event(Event.GET_PHYSICAL_ADDRESS,local_addr));
PingData coord_data=new PingData(local_addr, true, NameCache.get(local_addr), physical_addr).coord(is_coord);
write(Collections.singletonList(coord_data), cluster_name);
return;
}
if(!initial_discovery) {
for(PingData data : responses)
handleDiscoveryResponse(data, data.sender);
}
PhysicalAddress phys_addr=(PhysicalAddress)down_prot.down(new Event(Event.GET_PHYSICAL_ADDRESS, local_addr));
PingData data=responses.findResponseFrom(local_addr);
// the logical addr *and* IP address:port have to match
if(data != null && data.getPhysicalAddr().equals(phys_addr)) {
if(data.isCoord() && initial_discovery)
responses.clear();
else
; // use case #1 if we have predefined files: most members join but are not coord
}
else {
sendDiscoveryResponse(local_addr, phys_addr, NameCache.get(local_addr), null, is_coord);
}
// write the data if write_data_on_find is true
if(write_data_on_find && (remove_all_data_on_view_change || remove_old_coords_on_view_change)
&& !initial_discovery && is_coord && (data == null || !data.isCoord()) && !isInfoWriterRunning()) {
// a coordinator in a separate partition may have deleted this coordinator's file
writeAll();
}
}
finally {
responses.done();
}
}
protected static String addressToFilename(Address mbr) {
String logical_name=NameCache.get(mbr);
String name=(addressAsString(mbr) + (logical_name != null? "." + logical_name + SUFFIX : SUFFIX));
return regexp.matcher(name).replaceAll("-");
}
protected void createRootDir() {
root_dir=new File(location);
if(root_dir.exists()) {
if(!root_dir.isDirectory())
throw new IllegalArgumentException("location " + root_dir.getPath() + " is not a directory");
}
else
root_dir.mkdirs();
if(!root_dir.exists())
throw new IllegalArgumentException("location " + root_dir.getPath() + " could not be accessed");
}
// remove all files which are not from the current members
protected void handleView(View new_view, View old_view, boolean coord_changed) {
if(is_coord) {
if(remove_all_data_on_view_change)
removeAll(cluster_name);
else if(remove_old_coords_on_view_change) {
Address old_coord=old_view != null? old_view.getCreator() : null;
if(old_coord != null)
remove(cluster_name, old_coord);
}
Address[] left=View.diff(old_view, new_view)[1];
if(coord_changed || update_store_on_view_change || left.length > 0) {
writeAll(left);
if(remove_all_data_on_view_change || remove_old_coords_on_view_change)
startInfoWriter();
}
}
else if(coord_changed) // I'm no longer the coordinator
remove(cluster_name, local_addr);
}
protected void remove(String clustername, Address addr) {
if(clustername == null || addr == null)
return;
File dir=new File(root_dir, clustername);
if(!dir.exists())
return;
String filename=addressToFilename(addr);
File file=new File(dir, filename);
deleteFile(file);
}
/** Removes all files for the given cluster name */
protected void removeAll(String clustername) {
if(clustername == null)
return;
File dir=new File(root_dir, clustername);
if(!dir.exists())
return;
File[] files=dir.listFiles(filter); // finds all files ending with '.list'
for(File file: files)
file.delete();
}
protected void readAll(List members, String clustername, Responses responses) {
File dir=new File(root_dir, clustername);
if(!dir.exists())
dir.mkdir();
File[] files=dir.listFiles(filter); // finds all files ending with '.list'
for(File file: files) {
List list=null;
// implementing a simple spin lock doing a few attempts to read the file
// this is done since the file may be written in concurrency and may therefore not be readable
for(int i=0; i < 3; i++) {
if(file.exists()) {
try {
if((list=read(file)) != null)
break;
}
catch(Exception e) {
}
}
Util.sleep(50);
}
if(list == null) {
log.warn("failed reading " + file.getAbsolutePath());
continue;
}
for(PingData data: list) {
if(members == null || members.contains(data.getAddress()))
responses.addResponse(data, true);
if(local_addr != null && !local_addr.equals(data.getAddress()))
addDiscoveryResponseToCaches(data.getAddress(), data.getLogicalName(), data.getPhysicalAddr());
}
}
}
// Format: [name] [UUID] [address:port] [coord (T or F)]. See doc/design/CloudBasedDiscovery.txt for details
protected List read(File file) throws Exception {
return read(new FileInputStream(file));
}
@Override
protected List read(InputStream in) {
try {
return super.read(in);
}
finally {
reads++;
}
}
/** Write information about all of the member to file (only if I'm the coord) */
protected void writeAll() {
writeAll(null);
}
protected void writeAll(Address[] excluded_mbrs) {
Map cache_contents=
(Map)down_prot.down(new Event(Event.GET_LOGICAL_PHYSICAL_MAPPINGS, true));
if(excluded_mbrs != null)
for(Address excluded_mbr : excluded_mbrs)
cache_contents.remove(excluded_mbr);
List list=new ArrayList<>(cache_contents.size());
for(Map.Entry entry: cache_contents.entrySet()) {
Address addr=entry.getKey();
if(update_store_on_view_change && (view != null && !view.containsMember(addr)))
continue;
PhysicalAddress phys_addr=entry.getValue();
PingData data=new PingData(addr, true, NameCache.get(addr), phys_addr).coord(addr.equals(local_addr));
list.add(data);
}
write(list, cluster_name);
log.trace("%s: wrote to backend store: %s", local_addr, list.stream().map(PingData::getAddress).collect(Collectors.toList()));
}
protected void write(List list, String clustername) {
File dir=new File(root_dir, clustername);
if(!dir.exists())
dir.mkdir();
String filename=addressToFilename(local_addr);
File destination=new File(dir, filename);
try {
write(list, new FileOutputStream(destination));
}
catch(Exception ioe) {
log.error(Util.getMessage("AttemptToWriteDataFailedAt") + clustername + " : " + destination.getName(), ioe);
deleteFile(destination);
}
}
protected void write(List list, OutputStream out) throws Exception {
try {
super.write(list, out);
}
finally {
writes++;
}
}
protected boolean deleteFile(File file) {
boolean result = true;
if(file != null && file.exists()) {
try {
result=file.delete();
log.trace("deleted file %s: result=%b ", file.getAbsolutePath(), result);
}
catch(Throwable e) {
log.error(Util.getMessage("FailedToDeleteFile") + file.getAbsolutePath(), e);
}
}
return result;
}
protected synchronized void startInfoWriter() {
if(info_writer == null || info_writer.isDone())
info_writer=timer.scheduleWithDynamicInterval(new InfoWriter(info_writer_max_writes_after_view, info_writer_sleep_time));
}
protected synchronized void stopInfoWriter() {
if(info_writer != null)
info_writer.cancel(false);
}
/** Class which calls writeAll() a few times. Started after a view change in which an old coord left */
protected class InfoWriter implements TimeScheduler.Task {
protected final int max_writes;
protected int num_writes;
protected final long sleep_interval;
public InfoWriter(int max_writes, long sleep_interval) {
this.max_writes=max_writes;
this.sleep_interval=sleep_interval;
}
@Override
public long nextInterval() {
if(++num_writes > max_writes)
return 0; // discontinues this task
return Math.max(1000, Util.random(sleep_interval));
}
@Override
public void run() {
writeAll();
}
}
}