author | khazra |
Fri, 02 Mar 2012 13:48:43 -0800 | |
changeset 12040 | 558b0e0d5910 |
parent 5506 | 202f599c92aa |
child 14342 | 8435a30053c1 |
permissions | -rw-r--r-- |
2 | 1 |
/* |
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* Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package sun.rmi.transport; |
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import java.rmi.Remote; |
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import java.rmi.RemoteException; |
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import java.rmi.dgc.DGC; |
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import java.rmi.dgc.Lease; |
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import java.rmi.dgc.VMID; |
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import java.rmi.server.LogStream; |
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import java.rmi.server.ObjID; |
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import java.rmi.server.RemoteServer; |
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import java.rmi.server.ServerNotActiveException; |
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import java.security.AccessController; |
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import java.security.PrivilegedAction; |
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import java.util.ArrayList; |
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import java.util.HashSet; |
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import java.util.HashMap; |
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import java.util.Iterator; |
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import java.util.List; |
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import java.util.Map; |
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import java.util.Set; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.ScheduledExecutorService; |
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import java.util.concurrent.TimeUnit; |
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import sun.rmi.runtime.Log; |
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import sun.rmi.runtime.RuntimeUtil; |
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import sun.rmi.server.UnicastRef; |
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import sun.rmi.server.UnicastServerRef; |
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import sun.rmi.server.Util; |
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import sun.security.action.GetLongAction; |
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import sun.security.action.GetPropertyAction; |
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/** |
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* This class implements the guts of the server-side distributed GC |
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* algorithm |
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* |
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* @author Ann Wollrath |
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*/ |
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final class DGCImpl implements DGC { |
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/* dgc system log */ |
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static final Log dgcLog = Log.getLog("sun.rmi.dgc", "dgc", |
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LogStream.parseLevel(AccessController.doPrivileged( |
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new GetPropertyAction("sun.rmi.dgc.logLevel")))); |
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/** lease duration to grant to clients */ |
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private static final long leaseValue = // default 10 minutes |
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AccessController.doPrivileged( |
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new GetLongAction("java.rmi.dgc.leaseValue", 600000)); |
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/** lease check interval; default is half of lease grant duration */ |
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private static final long leaseCheckInterval = |
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AccessController.doPrivileged( |
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new GetLongAction("sun.rmi.dgc.checkInterval", leaseValue / 2)); |
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/** thread pool for scheduling delayed tasks */ |
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private static final ScheduledExecutorService scheduler = |
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AccessController.doPrivileged( |
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new RuntimeUtil.GetInstanceAction()).getScheduler(); |
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/** remote implementation of DGC interface for this VM */ |
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private static DGCImpl dgc; |
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/** table that maps VMID to LeaseInfo */ |
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12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
5506
diff
changeset
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private Map<VMID,LeaseInfo> leaseTable = new HashMap<>(); |
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/** checks for lease expiration */ |
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private Future<?> checker = null; |
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/** |
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* Return the remote implementation of the DGC interface for |
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* this VM. |
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*/ |
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static DGCImpl getDGCImpl() { |
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return dgc; |
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} |
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/** |
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* Construct a new server-side remote object collector at |
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* a particular port. Disallow construction from outside. |
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*/ |
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private DGCImpl() {} |
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/** |
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* The dirty call adds the VMID "vmid" to the set of clients |
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* that hold references to the object associated with the ObjID |
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* id. The long "sequenceNum" is used to detect late dirty calls. If |
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* the VMID "vmid" is null, a VMID will be generated on the |
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* server (for use by the client in subsequent calls) and |
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* returned. |
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* |
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* The client must call the "dirty" method to renew the lease |
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* before the "lease" time expires or all references to remote |
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* objects in this VM that the client holds are considered |
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* "unreferenced". |
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*/ |
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public Lease dirty(ObjID[] ids, long sequenceNum, Lease lease) { |
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VMID vmid = lease.getVMID(); |
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/* |
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* The server specifies the lease value; the client has |
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* no say in the matter. |
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*/ |
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long duration = leaseValue; |
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if (dgcLog.isLoggable(Log.VERBOSE)) { |
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dgcLog.log(Log.VERBOSE, "vmid = " + vmid); |
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} |
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// create a VMID if one wasn't supplied |
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if (vmid == null) { |
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vmid = new VMID(); |
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if (dgcLog.isLoggable(Log.BRIEF)) { |
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String clientHost; |
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try { |
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clientHost = RemoteServer.getClientHost(); |
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} catch (ServerNotActiveException e) { |
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clientHost = "<unknown host>"; |
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} |
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dgcLog.log(Log.BRIEF, " assigning vmid " + vmid + |
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" to client " + clientHost); |
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} |
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} |
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lease = new Lease(vmid, duration); |
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// record lease information |
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synchronized (leaseTable) { |
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LeaseInfo info = leaseTable.get(vmid); |
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if (info == null) { |
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leaseTable.put(vmid, new LeaseInfo(vmid, duration)); |
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if (checker == null) { |
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checker = scheduler.scheduleWithFixedDelay( |
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new Runnable() { |
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public void run() { |
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checkLeases(); |
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} |
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}, |
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leaseCheckInterval, |
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leaseCheckInterval, TimeUnit.MILLISECONDS); |
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} |
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} else { |
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info.renew(duration); |
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} |
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} |
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for (ObjID id : ids) { |
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if (dgcLog.isLoggable(Log.VERBOSE)) { |
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dgcLog.log(Log.VERBOSE, "id = " + id + |
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", vmid = " + vmid + ", duration = " + duration); |
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} |
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ObjectTable.referenced(id, sequenceNum, vmid); |
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} |
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// return the VMID used |
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return lease; |
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} |
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/** |
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* The clean call removes the VMID from the set of clients |
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* that hold references to the object associated with the LiveRef |
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* ref. The sequence number is used to detect late clean calls. If the |
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* argument "strong" is true, then the clean call is a result of a |
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* failed "dirty" call, thus the sequence number for the VMID needs |
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* to be remembered until the client goes away. |
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*/ |
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public void clean(ObjID[] ids, long sequenceNum, VMID vmid, boolean strong) |
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{ |
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for (ObjID id : ids) { |
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if (dgcLog.isLoggable(Log.VERBOSE)) { |
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dgcLog.log(Log.VERBOSE, "id = " + id + |
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", vmid = " + vmid + ", strong = " + strong); |
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} |
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ObjectTable.unreferenced(id, sequenceNum, vmid, strong); |
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} |
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} |
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/** |
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* Register interest in receiving a callback when this VMID |
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* becomes inaccessible. |
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*/ |
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void registerTarget(VMID vmid, Target target) { |
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synchronized (leaseTable) { |
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LeaseInfo info = leaseTable.get(vmid); |
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if (info == null) { |
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target.vmidDead(vmid); |
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} else { |
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info.notifySet.add(target); |
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} |
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} |
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} |
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/** |
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* Remove notification request. |
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*/ |
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void unregisterTarget(VMID vmid, Target target) { |
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synchronized (leaseTable) { |
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LeaseInfo info = leaseTable.get(vmid); |
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if (info != null) { |
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info.notifySet.remove(target); |
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} |
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} |
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} |
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/** |
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* Check if leases have expired. If a lease has expired, remove |
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* it from the table and notify all interested parties that the |
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* VMID is essentially "dead". |
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* |
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* @return if true, there are leases outstanding; otherwise leases |
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* no longer need to be checked |
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*/ |
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private void checkLeases() { |
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long time = System.currentTimeMillis(); |
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/* List of vmids that need to be removed from the leaseTable */ |
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12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
5506
diff
changeset
|
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List<LeaseInfo> toUnregister = new ArrayList<>(); |
2 | 240 |
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/* Build a list of leaseInfo objects that need to have |
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* targets removed from their notifySet. Remove expired |
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* leases from leaseTable. |
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*/ |
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synchronized (leaseTable) { |
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Iterator<LeaseInfo> iter = leaseTable.values().iterator(); |
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while (iter.hasNext()) { |
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LeaseInfo info = iter.next(); |
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if (info.expired(time)) { |
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toUnregister.add(info); |
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iter.remove(); |
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} |
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} |
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if (leaseTable.isEmpty()) { |
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checker.cancel(false); |
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checker = null; |
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} |
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} |
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/* Notify and unegister targets without holding the lock on |
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* the leaseTable so we avoid deadlock. |
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*/ |
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for (LeaseInfo info : toUnregister) { |
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for (Target target : info.notifySet) { |
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target.vmidDead(info.vmid); |
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} |
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} |
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} |
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static { |
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/* |
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* "Export" the singleton DGCImpl in a context isolated from |
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* the arbitrary current thread context. |
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*/ |
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AccessController.doPrivileged(new PrivilegedAction<Void>() { |
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public Void run() { |
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ClassLoader savedCcl = |
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Thread.currentThread().getContextClassLoader(); |
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try { |
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Thread.currentThread().setContextClassLoader( |
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ClassLoader.getSystemClassLoader()); |
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/* |
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* Put remote collector object in table by hand to prevent |
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* listen on port. (UnicastServerRef.exportObject would |
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* cause transport to listen.) |
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*/ |
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try { |
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dgc = new DGCImpl(); |
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ObjID dgcID = new ObjID(ObjID.DGC_ID); |
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LiveRef ref = new LiveRef(dgcID, 0); |
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UnicastServerRef disp = new UnicastServerRef(ref); |
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Remote stub = |
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Util.createProxy(DGCImpl.class, |
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new UnicastRef(ref), true); |
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disp.setSkeleton(dgc); |
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Target target = |
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new Target(dgc, disp, stub, dgcID, true); |
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ObjectTable.putTarget(target); |
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} catch (RemoteException e) { |
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throw new Error( |
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"exception initializing server-side DGC", e); |
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} |
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} finally { |
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Thread.currentThread().setContextClassLoader(savedCcl); |
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} |
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return null; |
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} |
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}); |
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} |
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private static class LeaseInfo { |
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VMID vmid; |
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315 |
long expiration; |
|
12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
5506
diff
changeset
|
316 |
Set<Target> notifySet = new HashSet<>(); |
2 | 317 |
|
318 |
LeaseInfo(VMID vmid, long lease) { |
|
319 |
this.vmid = vmid; |
|
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expiration = System.currentTimeMillis() + lease; |
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} |
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||
323 |
synchronized void renew(long lease) { |
|
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long newExpiration = System.currentTimeMillis() + lease; |
|
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if (newExpiration > expiration) |
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expiration = newExpiration; |
|
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} |
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||
329 |
boolean expired(long time) { |
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if (expiration < time) { |
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if (dgcLog.isLoggable(Log.BRIEF)) { |
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dgcLog.log(Log.BRIEF, vmid.toString()); |
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} |
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return true; |
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} else { |
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return false; |
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} |
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} |
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} |
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340 |
} |