| /* |
| * Copyright (c) 1996, 2008, 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.lang.ref.PhantomReference; |
| import java.lang.ref.ReferenceQueue; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.rmi.ConnectException; |
| import java.rmi.RemoteException; |
| import java.rmi.dgc.DGC; |
| import java.rmi.dgc.Lease; |
| import java.rmi.dgc.VMID; |
| import java.rmi.server.ObjID; |
| import sun.misc.GC; |
| import sun.rmi.runtime.NewThreadAction; |
| import sun.rmi.server.UnicastRef; |
| import sun.rmi.server.Util; |
| import sun.security.action.GetLongAction; |
| |
| /** |
| * DGCClient implements the client-side of the RMI distributed garbage |
| * collection system. |
| * |
| * The external interface to DGCClient is the "registerRefs" method. |
| * When a LiveRef to a remote object enters the VM, it needs to be |
| * registered with the DGCClient to participate in distributed garbage |
| * collection. |
| * |
| * When the first LiveRef to a particular remote object is registered, |
| * a "dirty" call is made to the server-side distributed garbage |
| * collector for the remote object, which returns a lease guaranteeing |
| * that the server-side DGC will not collect the remote object for a |
| * certain period of time. While LiveRef instances to remote objects |
| * on a particular server exist, the DGCClient periodically sends more |
| * "dirty" calls to renew its lease. |
| * |
| * The DGCClient tracks the local reachability of registered LiveRef |
| * instances (using phantom references). When the LiveRef instance |
| * for a particular remote object becomes garbage collected locally, |
| * a "clean" call is made to the server-side distributed garbage |
| * collector, indicating that the server no longer needs to keep the |
| * remote object alive for this client. |
| * |
| * @see java.rmi.dgc.DGC, sun.rmi.transport.DGCImpl |
| * |
| * @author Ann Wollrath |
| * @author Peter Jones |
| */ |
| final class DGCClient { |
| |
| /** next sequence number for DGC calls (access synchronized on class) */ |
| private static long nextSequenceNum = Long.MIN_VALUE; |
| |
| /** unique identifier for this VM as a client of DGC */ |
| private static VMID vmid = new VMID(); |
| |
| /** lease duration to request (usually ignored by server) */ |
| private static final long leaseValue = // default 10 minutes |
| AccessController.doPrivileged( |
| new GetLongAction("java.rmi.dgc.leaseValue", |
| 600000)).longValue(); |
| |
| /** maximum interval between retries of failed clean calls */ |
| private static final long cleanInterval = // default 3 minutes |
| AccessController.doPrivileged( |
| new GetLongAction("sun.rmi.dgc.cleanInterval", |
| 180000)).longValue(); |
| |
| /** maximum interval between complete garbage collections of local heap */ |
| private static final long gcInterval = // default 1 hour |
| AccessController.doPrivileged( |
| new GetLongAction("sun.rmi.dgc.client.gcInterval", |
| 3600000)).longValue(); |
| |
| /** minimum retry count for dirty calls that fail */ |
| private static final int dirtyFailureRetries = 5; |
| |
| /** retry count for clean calls that fail with ConnectException */ |
| private static final int cleanFailureRetries = 5; |
| |
| /** constant empty ObjID array for lease renewal optimization */ |
| private static final ObjID[] emptyObjIDArray = new ObjID[0]; |
| |
| /** ObjID for server-side DGC object */ |
| private static final ObjID dgcID = new ObjID(ObjID.DGC_ID); |
| |
| /* |
| * Disallow anyone from creating one of these. |
| */ |
| private DGCClient() {} |
| |
| /** |
| * Register the LiveRef instances in the supplied list to participate |
| * in distributed garbage collection. |
| * |
| * All of the LiveRefs in the list must be for remote objects at the |
| * given endpoint. |
| */ |
| static void registerRefs(Endpoint ep, List refs) { |
| /* |
| * Look up the given endpoint and register the refs with it. |
| * The retrieved entry may get removed from the global endpoint |
| * table before EndpointEntry.registerRefs() is able to acquire |
| * its lock; in this event, it returns false, and we loop and |
| * try again. |
| */ |
| EndpointEntry epEntry; |
| do { |
| epEntry = EndpointEntry.lookup(ep); |
| } while (!epEntry.registerRefs(refs)); |
| } |
| |
| /** |
| * Get the next sequence number to be used for a dirty or clean |
| * operation from this VM. This method should only be called while |
| * synchronized on the EndpointEntry whose data structures the |
| * operation affects. |
| */ |
| private static synchronized long getNextSequenceNum() { |
| return nextSequenceNum++; |
| } |
| |
| /** |
| * Given the length of a lease and the time that it was granted, |
| * compute the absolute time at which it should be renewed, giving |
| * room for reasonable computational and communication delays. |
| */ |
| private static long computeRenewTime(long grantTime, long duration) { |
| /* |
| * REMIND: This algorithm should be more sophisticated, waiting |
| * a longer fraction of the lease duration for longer leases. |
| */ |
| return grantTime + (duration / 2); |
| } |
| |
| /** |
| * EndpointEntry encapsulates the client-side DGC information specific |
| * to a particular Endpoint. Of most significance is the table that |
| * maps LiveRef value to RefEntry objects and the renew/clean thread |
| * that handles asynchronous client-side DGC operations. |
| */ |
| private static class EndpointEntry { |
| |
| /** the endpoint that this entry is for */ |
| private Endpoint endpoint; |
| /** synthesized reference to the remote server-side DGC */ |
| private DGC dgc; |
| |
| /** table of refs held for endpoint: maps LiveRef to RefEntry */ |
| private Map refTable = new HashMap(5); |
| /** set of RefEntry instances from last (failed) dirty call */ |
| private Set invalidRefs = new HashSet(5); |
| |
| /** true if this entry has been removed from the global table */ |
| private boolean removed = false; |
| |
| /** absolute time to renew current lease to this endpoint */ |
| private long renewTime = Long.MAX_VALUE; |
| /** absolute time current lease to this endpoint will expire */ |
| private long expirationTime = Long.MIN_VALUE; |
| /** count of recent dirty calls that have failed */ |
| private int dirtyFailures = 0; |
| /** absolute time of first recent failed dirty call */ |
| private long dirtyFailureStartTime; |
| /** (average) elapsed time for recent failed dirty calls */ |
| private long dirtyFailureDuration; |
| |
| /** renew/clean thread for handling lease renewals and clean calls */ |
| private Thread renewCleanThread; |
| /** true if renew/clean thread may be interrupted */ |
| private boolean interruptible = false; |
| |
| /** reference queue for phantom references */ |
| private ReferenceQueue refQueue = new ReferenceQueue(); |
| /** set of clean calls that need to be made */ |
| private Set pendingCleans = new HashSet(5); |
| |
| /** global endpoint table: maps Endpoint to EndpointEntry */ |
| private static Map endpointTable = new HashMap(5); |
| /** handle for GC latency request (for future cancellation) */ |
| private static GC.LatencyRequest gcLatencyRequest = null; |
| |
| /** |
| * Look up the EndpointEntry for the given Endpoint. An entry is |
| * created if one does not already exist. |
| */ |
| public static EndpointEntry lookup(Endpoint ep) { |
| synchronized (endpointTable) { |
| EndpointEntry entry = (EndpointEntry) endpointTable.get(ep); |
| if (entry == null) { |
| entry = new EndpointEntry(ep); |
| endpointTable.put(ep, entry); |
| /* |
| * While we are tracking live remote references registered |
| * in this VM, request a maximum latency for inspecting the |
| * entire heap from the local garbage collector, to place |
| * an upper bound on the time to discover remote references |
| * that have become unreachable (see bugid 4171278). |
| */ |
| if (gcLatencyRequest == null) { |
| gcLatencyRequest = GC.requestLatency(gcInterval); |
| } |
| } |
| return entry; |
| } |
| } |
| |
| private EndpointEntry(final Endpoint endpoint) { |
| this.endpoint = endpoint; |
| try { |
| LiveRef dgcRef = new LiveRef(dgcID, endpoint, false); |
| dgc = (DGC) Util.createProxy(DGCImpl.class, |
| new UnicastRef(dgcRef), true); |
| } catch (RemoteException e) { |
| throw new Error("internal error creating DGC stub"); |
| } |
| renewCleanThread = AccessController.doPrivileged( |
| new NewThreadAction(new RenewCleanThread(), |
| "RenewClean-" + endpoint, true)); |
| renewCleanThread.start(); |
| } |
| |
| /** |
| * Register the LiveRef instances in the supplied list to participate |
| * in distributed garbage collection. |
| * |
| * This method returns false if this entry was removed from the |
| * global endpoint table (because it was empty) before these refs |
| * could be registered. In that case, a new EndpointEntry needs |
| * to be looked up. |
| * |
| * This method must NOT be called while synchronized on this entry. |
| */ |
| public boolean registerRefs(List refs) { |
| assert !Thread.holdsLock(this); |
| |
| Set refsToDirty = null; // entries for refs needing dirty |
| long sequenceNum; // sequence number for dirty call |
| |
| synchronized (this) { |
| if (removed) { |
| return false; |
| } |
| |
| Iterator iter = refs.iterator(); |
| while (iter.hasNext()) { |
| LiveRef ref = (LiveRef) iter.next(); |
| assert ref.getEndpoint().equals(endpoint); |
| |
| RefEntry refEntry = (RefEntry) refTable.get(ref); |
| if (refEntry == null) { |
| LiveRef refClone = (LiveRef) ref.clone(); |
| refEntry = new RefEntry(refClone); |
| refTable.put(refClone, refEntry); |
| if (refsToDirty == null) { |
| refsToDirty = new HashSet(5); |
| } |
| refsToDirty.add(refEntry); |
| } |
| |
| refEntry.addInstanceToRefSet(ref); |
| } |
| |
| if (refsToDirty == null) { |
| return true; |
| } |
| |
| refsToDirty.addAll(invalidRefs); |
| invalidRefs.clear(); |
| |
| sequenceNum = getNextSequenceNum(); |
| } |
| |
| makeDirtyCall(refsToDirty, sequenceNum); |
| return true; |
| } |
| |
| /** |
| * Remove the given RefEntry from the ref table. If that makes |
| * the ref table empty, remove this entry from the global endpoint |
| * table. |
| * |
| * This method must ONLY be called while synchronized on this entry. |
| */ |
| private void removeRefEntry(RefEntry refEntry) { |
| assert Thread.holdsLock(this); |
| assert !removed; |
| assert refTable.containsKey(refEntry.getRef()); |
| |
| refTable.remove(refEntry.getRef()); |
| invalidRefs.remove(refEntry); |
| if (refTable.isEmpty()) { |
| synchronized (endpointTable) { |
| endpointTable.remove(endpoint); |
| Transport transport = endpoint.getOutboundTransport(); |
| transport.free(endpoint); |
| /* |
| * If there are no longer any live remote references |
| * registered, we are no longer concerned with the |
| * latency of local garbage collection here. |
| */ |
| if (endpointTable.isEmpty()) { |
| assert gcLatencyRequest != null; |
| gcLatencyRequest.cancel(); |
| gcLatencyRequest = null; |
| } |
| removed = true; |
| } |
| } |
| } |
| |
| /** |
| * Make a DGC dirty call to this entry's endpoint, for the ObjIDs |
| * corresponding to the given set of refs and with the given |
| * sequence number. |
| * |
| * This method must NOT be called while synchronized on this entry. |
| */ |
| private void makeDirtyCall(Set refEntries, long sequenceNum) { |
| assert !Thread.holdsLock(this); |
| |
| ObjID[] ids; |
| if (refEntries != null) { |
| ids = createObjIDArray(refEntries); |
| } else { |
| ids = emptyObjIDArray; |
| } |
| |
| long startTime = System.currentTimeMillis(); |
| try { |
| Lease lease = |
| dgc.dirty(ids, sequenceNum, new Lease(vmid, leaseValue)); |
| long duration = lease.getValue(); |
| |
| long newRenewTime = computeRenewTime(startTime, duration); |
| long newExpirationTime = startTime + duration; |
| |
| synchronized (this) { |
| dirtyFailures = 0; |
| setRenewTime(newRenewTime); |
| expirationTime = newExpirationTime; |
| } |
| |
| } catch (Exception e) { |
| long endTime = System.currentTimeMillis(); |
| |
| synchronized (this) { |
| dirtyFailures++; |
| |
| if (dirtyFailures == 1) { |
| /* |
| * If this was the first recent failed dirty call, |
| * reschedule another one immediately, in case there |
| * was just a transient network problem, and remember |
| * the start time and duration of this attempt for |
| * future calculations of the delays between retries. |
| */ |
| dirtyFailureStartTime = startTime; |
| dirtyFailureDuration = endTime - startTime; |
| setRenewTime(endTime); |
| } else { |
| /* |
| * For each successive failed dirty call, wait for a |
| * (binary) exponentially increasing delay before |
| * retrying, to avoid network congestion. |
| */ |
| int n = dirtyFailures - 2; |
| if (n == 0) { |
| /* |
| * Calculate the initial retry delay from the |
| * average time elapsed for each of the first |
| * two failed dirty calls. The result must be |
| * at least 1000ms, to prevent a tight loop. |
| */ |
| dirtyFailureDuration = |
| Math.max((dirtyFailureDuration + |
| (endTime - startTime)) >> 1, 1000); |
| } |
| long newRenewTime = |
| endTime + (dirtyFailureDuration << n); |
| |
| /* |
| * Continue if the last known held lease has not |
| * expired, or else at least a fixed number of times, |
| * or at least until we've tried for a fixed amount |
| * of time (the default lease value we request). |
| */ |
| if (newRenewTime < expirationTime || |
| dirtyFailures < dirtyFailureRetries || |
| newRenewTime < dirtyFailureStartTime + leaseValue) |
| { |
| setRenewTime(newRenewTime); |
| } else { |
| /* |
| * Give up: postpone lease renewals until next |
| * ref is registered for this endpoint. |
| */ |
| setRenewTime(Long.MAX_VALUE); |
| } |
| } |
| |
| if (refEntries != null) { |
| /* |
| * Add all of these refs to the set of refs for this |
| * endpoint that may be invalid (this VM may not be in |
| * the server's referenced set), so that we will |
| * attempt to explicitly dirty them again in the |
| * future. |
| */ |
| invalidRefs.addAll(refEntries); |
| |
| /* |
| * Record that a dirty call has failed for all of these |
| * refs, so that clean calls for them in the future |
| * will be strong. |
| */ |
| Iterator iter = refEntries.iterator(); |
| while (iter.hasNext()) { |
| RefEntry refEntry = (RefEntry) iter.next(); |
| refEntry.markDirtyFailed(); |
| } |
| } |
| |
| /* |
| * If the last known held lease will have expired before |
| * the next renewal, all refs might be invalid. |
| */ |
| if (renewTime >= expirationTime) { |
| invalidRefs.addAll(refTable.values()); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Set the absolute time at which the lease for this entry should |
| * be renewed. |
| * |
| * This method must ONLY be called while synchronized on this entry. |
| */ |
| private void setRenewTime(long newRenewTime) { |
| assert Thread.holdsLock(this); |
| |
| if (newRenewTime < renewTime) { |
| renewTime = newRenewTime; |
| if (interruptible) { |
| AccessController.doPrivileged( |
| new PrivilegedAction<Void>() { |
| public Void run() { |
| renewCleanThread.interrupt(); |
| return null; |
| } |
| }); |
| } |
| } else { |
| renewTime = newRenewTime; |
| } |
| } |
| |
| /** |
| * RenewCleanThread handles the asynchronous client-side DGC activity |
| * for this entry: renewing the leases and making clean calls. |
| */ |
| private class RenewCleanThread implements Runnable { |
| |
| public void run() { |
| do { |
| long timeToWait; |
| RefEntry.PhantomLiveRef phantom = null; |
| boolean needRenewal = false; |
| Set refsToDirty = null; |
| long sequenceNum = Long.MIN_VALUE; |
| |
| synchronized (EndpointEntry.this) { |
| /* |
| * Calculate time to block (waiting for phantom |
| * reference notifications). It is the time until the |
| * lease renewal should be done, bounded on the low |
| * end by 1 ms so that the reference queue will always |
| * get processed, and if there are pending clean |
| * requests (remaining because some clean calls |
| * failed), bounded on the high end by the maximum |
| * clean call retry interval. |
| */ |
| long timeUntilRenew = |
| renewTime - System.currentTimeMillis(); |
| timeToWait = Math.max(timeUntilRenew, 1); |
| if (!pendingCleans.isEmpty()) { |
| timeToWait = Math.min(timeToWait, cleanInterval); |
| } |
| |
| /* |
| * Set flag indicating that it is OK to interrupt this |
| * thread now, such as if a earlier lease renewal time |
| * is set, because we are only going to be blocking |
| * and can deal with interrupts. |
| */ |
| interruptible = true; |
| } |
| |
| try { |
| /* |
| * Wait for the duration calculated above for any of |
| * our phantom references to be enqueued. |
| */ |
| phantom = (RefEntry.PhantomLiveRef) |
| refQueue.remove(timeToWait); |
| } catch (InterruptedException e) { |
| } |
| |
| synchronized (EndpointEntry.this) { |
| /* |
| * Set flag indicating that it is NOT OK to interrupt |
| * this thread now, because we may be undertaking I/O |
| * operations that should not be interrupted (and we |
| * will not be blocking arbitrarily). |
| */ |
| interruptible = false; |
| Thread.interrupted(); // clear interrupted state |
| |
| /* |
| * If there was a phantom reference enqueued, process |
| * it and all the rest on the queue, generating |
| * clean requests as necessary. |
| */ |
| if (phantom != null) { |
| processPhantomRefs(phantom); |
| } |
| |
| /* |
| * Check if it is time to renew this entry's lease. |
| */ |
| long currentTime = System.currentTimeMillis(); |
| if (currentTime > renewTime) { |
| needRenewal = true; |
| if (!invalidRefs.isEmpty()) { |
| refsToDirty = invalidRefs; |
| invalidRefs = new HashSet(5); |
| } |
| sequenceNum = getNextSequenceNum(); |
| } |
| } |
| |
| if (needRenewal) { |
| makeDirtyCall(refsToDirty, sequenceNum); |
| } |
| |
| if (!pendingCleans.isEmpty()) { |
| makeCleanCalls(); |
| } |
| } while (!removed || !pendingCleans.isEmpty()); |
| } |
| } |
| |
| /** |
| * Process the notification of the given phantom reference and any |
| * others that are on this entry's reference queue. Each phantom |
| * reference is removed from its RefEntry's ref set. All ref |
| * entries that have no more registered instances are collected |
| * into up to two batched clean call requests: one for refs |
| * requiring a "strong" clean call, and one for the rest. |
| * |
| * This method must ONLY be called while synchronized on this entry. |
| */ |
| private void processPhantomRefs(RefEntry.PhantomLiveRef phantom) { |
| assert Thread.holdsLock(this); |
| |
| Set strongCleans = null; |
| Set normalCleans = null; |
| |
| do { |
| RefEntry refEntry = phantom.getRefEntry(); |
| refEntry.removeInstanceFromRefSet(phantom); |
| if (refEntry.isRefSetEmpty()) { |
| if (refEntry.hasDirtyFailed()) { |
| if (strongCleans == null) { |
| strongCleans = new HashSet(5); |
| } |
| strongCleans.add(refEntry); |
| } else { |
| if (normalCleans == null) { |
| normalCleans = new HashSet(5); |
| } |
| normalCleans.add(refEntry); |
| } |
| removeRefEntry(refEntry); |
| } |
| } while ((phantom = |
| (RefEntry.PhantomLiveRef) refQueue.poll()) != null); |
| |
| if (strongCleans != null) { |
| pendingCleans.add( |
| new CleanRequest(createObjIDArray(strongCleans), |
| getNextSequenceNum(), true)); |
| } |
| if (normalCleans != null) { |
| pendingCleans.add( |
| new CleanRequest(createObjIDArray(normalCleans), |
| getNextSequenceNum(), false)); |
| } |
| } |
| |
| /** |
| * CleanRequest holds the data for the parameters of a clean call |
| * that needs to be made. |
| */ |
| private static class CleanRequest { |
| |
| final ObjID[] objIDs; |
| final long sequenceNum; |
| final boolean strong; |
| |
| /** how many times this request has failed */ |
| int failures = 0; |
| |
| CleanRequest(ObjID[] objIDs, long sequenceNum, boolean strong) { |
| this.objIDs = objIDs; |
| this.sequenceNum = sequenceNum; |
| this.strong = strong; |
| } |
| } |
| |
| /** |
| * Make all of the clean calls described by the clean requests in |
| * this entry's set of "pending cleans". Clean requests for clean |
| * calls that succeed are removed from the "pending cleans" set. |
| * |
| * This method must NOT be called while synchronized on this entry. |
| */ |
| private void makeCleanCalls() { |
| assert !Thread.holdsLock(this); |
| |
| Iterator iter = pendingCleans.iterator(); |
| while (iter.hasNext()) { |
| CleanRequest request = (CleanRequest) iter.next(); |
| try { |
| dgc.clean(request.objIDs, request.sequenceNum, vmid, |
| request.strong); |
| iter.remove(); |
| } catch (Exception e) { |
| /* |
| * Many types of exceptions here could have been |
| * caused by a transient failure, so try again a |
| * few times, but not forever. |
| */ |
| if (++request.failures >= cleanFailureRetries) { |
| iter.remove(); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Create an array of ObjIDs (needed for the DGC remote calls) |
| * from the ids in the given set of refs. |
| */ |
| private static ObjID[] createObjIDArray(Set refEntries) { |
| ObjID[] ids = new ObjID[refEntries.size()]; |
| Iterator iter = refEntries.iterator(); |
| for (int i = 0; i < ids.length; i++) { |
| ids[i] = ((RefEntry) iter.next()).getRef().getObjID(); |
| } |
| return ids; |
| } |
| |
| /** |
| * RefEntry encapsulates the client-side DGC information specific |
| * to a particular LiveRef value. In particular, it contains a |
| * set of phantom references to all of the instances of the LiveRef |
| * value registered in the system (but not garbage collected |
| * locally). |
| */ |
| private class RefEntry { |
| |
| /** LiveRef value for this entry (not a registered instance) */ |
| private LiveRef ref; |
| /** set of phantom references to registered instances */ |
| private Set refSet = new HashSet(5); |
| /** true if a dirty call containing this ref has failed */ |
| private boolean dirtyFailed = false; |
| |
| public RefEntry(LiveRef ref) { |
| this.ref = ref; |
| } |
| |
| /** |
| * Return the LiveRef value for this entry (not a registered |
| * instance). |
| */ |
| public LiveRef getRef() { |
| return ref; |
| } |
| |
| /** |
| * Add a LiveRef to the set of registered instances for this entry. |
| * |
| * This method must ONLY be invoked while synchronized on this |
| * RefEntry's EndpointEntry. |
| */ |
| public void addInstanceToRefSet(LiveRef ref) { |
| assert Thread.holdsLock(EndpointEntry.this); |
| assert ref.equals(this.ref); |
| |
| /* |
| * Only keep a phantom reference to the registered instance, |
| * so that it can be garbage collected normally (and we can be |
| * notified when that happens). |
| */ |
| refSet.add(new PhantomLiveRef(ref)); |
| } |
| |
| /** |
| * Remove a PhantomLiveRef from the set of registered instances. |
| * |
| * This method must ONLY be invoked while synchronized on this |
| * RefEntry's EndpointEntry. |
| */ |
| public void removeInstanceFromRefSet(PhantomLiveRef phantom) { |
| assert Thread.holdsLock(EndpointEntry.this); |
| assert refSet.contains(phantom); |
| refSet.remove(phantom); |
| } |
| |
| /** |
| * Return true if there are no registered LiveRef instances for |
| * this entry still reachable in this VM. |
| * |
| * This method must ONLY be invoked while synchronized on this |
| * RefEntry's EndpointEntry. |
| */ |
| public boolean isRefSetEmpty() { |
| assert Thread.holdsLock(EndpointEntry.this); |
| return refSet.size() == 0; |
| } |
| |
| /** |
| * Record that a dirty call that explicitly contained this |
| * entry's ref has failed. |
| * |
| * This method must ONLY be invoked while synchronized on this |
| * RefEntry's EndpointEntry. |
| */ |
| public void markDirtyFailed() { |
| assert Thread.holdsLock(EndpointEntry.this); |
| dirtyFailed = true; |
| } |
| |
| /** |
| * Return true if a dirty call that explicitly contained this |
| * entry's ref has failed (and therefore a clean call for this |
| * ref needs to be marked "strong"). |
| * |
| * This method must ONLY be invoked while synchronized on this |
| * RefEntry's EndpointEntry. |
| */ |
| public boolean hasDirtyFailed() { |
| assert Thread.holdsLock(EndpointEntry.this); |
| return dirtyFailed; |
| } |
| |
| /** |
| * PhantomLiveRef is a PhantomReference to a LiveRef instance, |
| * used to detect when the LiveRef becomes permanently |
| * unreachable in this VM. |
| */ |
| private class PhantomLiveRef extends PhantomReference { |
| |
| public PhantomLiveRef(LiveRef ref) { |
| super(ref, EndpointEntry.this.refQueue); |
| } |
| |
| public RefEntry getRefEntry() { |
| return RefEntry.this; |
| } |
| } |
| } |
| } |
| } |
