| /* |
| * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package sun.rmi.transport; |
| |
| import java.rmi.Remote; |
| import java.rmi.RemoteException; |
| import java.rmi.dgc.DGC; |
| import java.rmi.dgc.Lease; |
| import java.rmi.dgc.VMID; |
| import java.rmi.server.LogStream; |
| import java.rmi.server.ObjID; |
| import java.rmi.server.RemoteServer; |
| import java.rmi.server.ServerNotActiveException; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import java.util.ArrayList; |
| import java.util.HashSet; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| import sun.rmi.runtime.Log; |
| import sun.rmi.runtime.RuntimeUtil; |
| import sun.rmi.server.UnicastRef; |
| import sun.rmi.server.UnicastServerRef; |
| import sun.rmi.server.Util; |
| import sun.security.action.GetLongAction; |
| import sun.security.action.GetPropertyAction; |
| |
| /** |
| * This class implements the guts of the server-side distributed GC |
| * algorithm |
| * |
| * @author Ann Wollrath |
| */ |
| final class DGCImpl implements DGC { |
| |
| /* dgc system log */ |
| static final Log dgcLog = Log.getLog("sun.rmi.dgc", "dgc", |
| LogStream.parseLevel(AccessController.doPrivileged( |
| new GetPropertyAction("sun.rmi.dgc.logLevel")))); |
| |
| /** lease duration to grant to clients */ |
| private static final long leaseValue = // default 10 minutes |
| AccessController.doPrivileged( |
| new GetLongAction("java.rmi.dgc.leaseValue", 600000)); |
| |
| /** lease check interval; default is half of lease grant duration */ |
| private static final long leaseCheckInterval = |
| AccessController.doPrivileged( |
| new GetLongAction("sun.rmi.dgc.checkInterval", leaseValue / 2)); |
| |
| /** thread pool for scheduling delayed tasks */ |
| private static final ScheduledExecutorService scheduler = |
| AccessController.doPrivileged( |
| new RuntimeUtil.GetInstanceAction()).getScheduler(); |
| |
| /** remote implementation of DGC interface for this VM */ |
| private static DGCImpl dgc; |
| /** table that maps VMID to LeaseInfo */ |
| private Map<VMID,LeaseInfo> leaseTable = new HashMap<>(); |
| /** checks for lease expiration */ |
| private Future<?> checker = null; |
| |
| /** |
| * Return the remote implementation of the DGC interface for |
| * this VM. |
| */ |
| static DGCImpl getDGCImpl() { |
| return dgc; |
| } |
| |
| /** |
| * Construct a new server-side remote object collector at |
| * a particular port. Disallow construction from outside. |
| */ |
| private DGCImpl() {} |
| |
| /** |
| * The dirty call adds the VMID "vmid" to the set of clients |
| * that hold references to the object associated with the ObjID |
| * id. The long "sequenceNum" is used to detect late dirty calls. If |
| * the VMID "vmid" is null, a VMID will be generated on the |
| * server (for use by the client in subsequent calls) and |
| * returned. |
| * |
| * The client must call the "dirty" method to renew the lease |
| * before the "lease" time expires or all references to remote |
| * objects in this VM that the client holds are considered |
| * "unreferenced". |
| */ |
| public Lease dirty(ObjID[] ids, long sequenceNum, Lease lease) { |
| VMID vmid = lease.getVMID(); |
| /* |
| * The server specifies the lease value; the client has |
| * no say in the matter. |
| */ |
| long duration = leaseValue; |
| |
| if (dgcLog.isLoggable(Log.VERBOSE)) { |
| dgcLog.log(Log.VERBOSE, "vmid = " + vmid); |
| } |
| |
| // create a VMID if one wasn't supplied |
| if (vmid == null) { |
| vmid = new VMID(); |
| |
| if (dgcLog.isLoggable(Log.BRIEF)) { |
| String clientHost; |
| try { |
| clientHost = RemoteServer.getClientHost(); |
| } catch (ServerNotActiveException e) { |
| clientHost = "<unknown host>"; |
| } |
| dgcLog.log(Log.BRIEF, " assigning vmid " + vmid + |
| " to client " + clientHost); |
| } |
| } |
| |
| lease = new Lease(vmid, duration); |
| // record lease information |
| synchronized (leaseTable) { |
| LeaseInfo info = leaseTable.get(vmid); |
| if (info == null) { |
| leaseTable.put(vmid, new LeaseInfo(vmid, duration)); |
| if (checker == null) { |
| checker = scheduler.scheduleWithFixedDelay( |
| new Runnable() { |
| public void run() { |
| checkLeases(); |
| } |
| }, |
| leaseCheckInterval, |
| leaseCheckInterval, TimeUnit.MILLISECONDS); |
| } |
| } else { |
| info.renew(duration); |
| } |
| } |
| |
| for (ObjID id : ids) { |
| if (dgcLog.isLoggable(Log.VERBOSE)) { |
| dgcLog.log(Log.VERBOSE, "id = " + id + |
| ", vmid = " + vmid + ", duration = " + duration); |
| } |
| |
| ObjectTable.referenced(id, sequenceNum, vmid); |
| } |
| |
| // return the VMID used |
| return lease; |
| } |
| |
| /** |
| * The clean call removes the VMID from the set of clients |
| * that hold references to the object associated with the LiveRef |
| * ref. The sequence number is used to detect late clean calls. If the |
| * argument "strong" is true, then the clean call is a result of a |
| * failed "dirty" call, thus the sequence number for the VMID needs |
| * to be remembered until the client goes away. |
| */ |
| public void clean(ObjID[] ids, long sequenceNum, VMID vmid, boolean strong) |
| { |
| for (ObjID id : ids) { |
| if (dgcLog.isLoggable(Log.VERBOSE)) { |
| dgcLog.log(Log.VERBOSE, "id = " + id + |
| ", vmid = " + vmid + ", strong = " + strong); |
| } |
| |
| ObjectTable.unreferenced(id, sequenceNum, vmid, strong); |
| } |
| } |
| |
| /** |
| * Register interest in receiving a callback when this VMID |
| * becomes inaccessible. |
| */ |
| void registerTarget(VMID vmid, Target target) { |
| synchronized (leaseTable) { |
| LeaseInfo info = leaseTable.get(vmid); |
| if (info == null) { |
| target.vmidDead(vmid); |
| } else { |
| info.notifySet.add(target); |
| } |
| } |
| } |
| |
| /** |
| * Remove notification request. |
| */ |
| void unregisterTarget(VMID vmid, Target target) { |
| synchronized (leaseTable) { |
| LeaseInfo info = leaseTable.get(vmid); |
| if (info != null) { |
| info.notifySet.remove(target); |
| } |
| } |
| } |
| |
| /** |
| * Check if leases have expired. If a lease has expired, remove |
| * it from the table and notify all interested parties that the |
| * VMID is essentially "dead". |
| * |
| * @return if true, there are leases outstanding; otherwise leases |
| * no longer need to be checked |
| */ |
| private void checkLeases() { |
| long time = System.currentTimeMillis(); |
| |
| /* List of vmids that need to be removed from the leaseTable */ |
| List<LeaseInfo> toUnregister = new ArrayList<>(); |
| |
| /* Build a list of leaseInfo objects that need to have |
| * targets removed from their notifySet. Remove expired |
| * leases from leaseTable. |
| */ |
| synchronized (leaseTable) { |
| Iterator<LeaseInfo> iter = leaseTable.values().iterator(); |
| while (iter.hasNext()) { |
| LeaseInfo info = iter.next(); |
| if (info.expired(time)) { |
| toUnregister.add(info); |
| iter.remove(); |
| } |
| } |
| |
| if (leaseTable.isEmpty()) { |
| checker.cancel(false); |
| checker = null; |
| } |
| } |
| |
| /* Notify and unegister targets without holding the lock on |
| * the leaseTable so we avoid deadlock. |
| */ |
| for (LeaseInfo info : toUnregister) { |
| for (Target target : info.notifySet) { |
| target.vmidDead(info.vmid); |
| } |
| } |
| } |
| |
| static { |
| /* |
| * "Export" the singleton DGCImpl in a context isolated from |
| * the arbitrary current thread context. |
| */ |
| AccessController.doPrivileged(new PrivilegedAction<Void>() { |
| public Void run() { |
| ClassLoader savedCcl = |
| Thread.currentThread().getContextClassLoader(); |
| try { |
| Thread.currentThread().setContextClassLoader( |
| ClassLoader.getSystemClassLoader()); |
| |
| /* |
| * Put remote collector object in table by hand to prevent |
| * listen on port. (UnicastServerRef.exportObject would |
| * cause transport to listen.) |
| */ |
| try { |
| dgc = new DGCImpl(); |
| ObjID dgcID = new ObjID(ObjID.DGC_ID); |
| LiveRef ref = new LiveRef(dgcID, 0); |
| UnicastServerRef disp = new UnicastServerRef(ref); |
| Remote stub = |
| Util.createProxy(DGCImpl.class, |
| new UnicastRef(ref), true); |
| disp.setSkeleton(dgc); |
| Target target = |
| new Target(dgc, disp, stub, dgcID, true); |
| ObjectTable.putTarget(target); |
| } catch (RemoteException e) { |
| throw new Error( |
| "exception initializing server-side DGC", e); |
| } |
| } finally { |
| Thread.currentThread().setContextClassLoader(savedCcl); |
| } |
| return null; |
| } |
| }); |
| } |
| |
| private static class LeaseInfo { |
| VMID vmid; |
| long expiration; |
| Set<Target> notifySet = new HashSet<>(); |
| |
| LeaseInfo(VMID vmid, long lease) { |
| this.vmid = vmid; |
| expiration = System.currentTimeMillis() + lease; |
| } |
| |
| synchronized void renew(long lease) { |
| long newExpiration = System.currentTimeMillis() + lease; |
| if (newExpiration > expiration) |
| expiration = newExpiration; |
| } |
| |
| boolean expired(long time) { |
| if (expiration < time) { |
| if (dgcLog.isLoggable(Log.BRIEF)) { |
| dgcLog.log(Log.BRIEF, vmid.toString()); |
| } |
| return true; |
| } else { |
| return false; |
| } |
| } |
| } |
| } |