org.jgroups.protocols.FILE_PING Maven / Gradle / Ivy
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.*;
import java.util.concurrent.Future;
import java.util.regex.Pattern;
/**
* 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 = "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;
@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;}
@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() {
public void run() {
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;
}
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, false);
}
}
finally {
responses.done();
}
}
/** Only add the discovery response if the logical address is not present or the physical addrs are different */
protected boolean addDiscoveryResponseToCaches(Address mbr, String logical_name, PhysicalAddress physical_addr) {
PhysicalAddress phys_addr=(PhysicalAddress)down_prot.down(new Event(Event.GET_PHYSICAL_ADDRESS, mbr));
boolean added=!Objects.equals(phys_addr, physical_addr);
super.addDiscoveryResponseToCaches(mbr, logical_name, physical_addr);
if(added && is_coord)
writeAll();
return added;
}
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(coord_changed) {
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);
}
}
if(coord_changed || View.diff(old_view, new_view)[1].length > 0) {
writeAll();
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;
log.debug("remove %s", clustername);
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() {
Map cache_contents=
(Map)down_prot.down(new Event(Event.GET_LOGICAL_PHYSICAL_MAPPINGS, false));
List list=new ArrayList<>(cache_contents.size());
for(Map.Entry entry: cache_contents.entrySet()) {
Address addr=entry.getKey();
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);
}
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(log.isTraceEnabled())
log.trace("Attempting to delete file : "+file.getAbsolutePath());
if(file != null && file.exists()) {
try {
result=file.delete();
log.trace("Deleted file result: "+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();
}
}
}
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