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A module of the Hibernate Core project
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate.cache.infinispan.access;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;
import org.hibernate.cache.infinispan.InfinispanRegionFactory;
import org.hibernate.cache.infinispan.util.CacheCommandInitializer;
import org.hibernate.cache.spi.RegionFactory;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.resource.transaction.TransactionCoordinator;
import org.infinispan.AdvancedCache;
import org.infinispan.configuration.cache.CacheMode;
import org.infinispan.configuration.cache.Configuration;
import org.infinispan.configuration.cache.ConfigurationBuilder;
import org.infinispan.interceptors.EntryWrappingInterceptor;
import org.infinispan.interceptors.InvalidationInterceptor;
import org.infinispan.interceptors.base.CommandInterceptor;
import org.infinispan.manager.EmbeddedCacheManager;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;
/**
* Encapsulates logic to allow a {@link InvalidationCacheAccessDelegate} to determine
* whether a {@link InvalidationCacheAccessDelegate#putFromLoad(org.hibernate.engine.spi.SessionImplementor, Object, Object, long, Object, boolean)}
* call should be allowed to update the cache. A putFromLoad has
* the potential to store stale data, since the data may have been removed from the
* database and the cache between the time when the data was read from the database
* and the actual call to putFromLoad.
*
* The expected usage of this class by a thread that read the cache and did
* not find data is:
*
*
* - Call {@link #registerPendingPut(SessionImplementor, Object, long)}
* - Read the database
* - Call {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)}
*
- if above returns
null, the thread should not cache the data;
* only if above returns instance of AcquiredLock, put data in the cache and...
* - then call {@link #releasePutFromLoadLock(Object, Lock)}
*
*
*
*
* The expected usage by a thread that is taking an action such that any pending
* putFromLoad may have stale data and should not cache it is to either
* call
*
*
* - {@link #beginInvalidatingKey(Object, Object)} (for a single key invalidation)
* - or {@link #beginInvalidatingRegion()} followed by {@link #endInvalidatingRegion()}
* (for a general invalidation all pending puts)
*
* After transaction commit (when the DB is updated) {@link #endInvalidatingKey(Object, Object)} should
* be called in order to allow further attempts to cache entry.
*
*
*
* This class also supports the concept of "naked puts", which are calls to
* {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)} without a preceding {@link #registerPendingPut(SessionImplementor, Object, long)}.
* Besides not acquiring lock in {@link #registerPendingPut(SessionImplementor, Object, long)} this can happen when collection
* elements are loaded after the collection has not been found in the cache, where the elements
* don't have their own table but can be listed as 'select ... from Element where collection_id = ...'.
* Naked puts are handled according to txTimestamp obtained by calling {@link RegionFactory#nextTimestamp()}
* before the transaction is started. The timestamp is compared with timestamp of last invalidation end time
* and the write to the cache is denied if it is lower or equal.
*
*
* @author Brian Stansberry
* @version $Revision: $
*/
public class PutFromLoadValidator {
private static final Log log = LogFactory.getLog(PutFromLoadValidator.class);
private static final boolean trace = log.isTraceEnabled();
/**
* Period after which ongoing invalidation is removed. Value is retrieved from cache configuration.
*/
private final long expirationPeriod;
/**
* Registry of expected, future, isPutValid calls. If a key+owner is registered in this map, it
* is not a "naked put" and is allowed to proceed.
*/
private final ConcurrentMap pendingPuts;
/**
* Main cache where the entities/collections are stored. This is not modified from within this class.
*/
private final AdvancedCache cache;
/**
* Injected interceptor
*/
private final NonTxPutFromLoadInterceptor nonTxPutFromLoadInterceptor;
/**
* The time of the last call to {@link #endInvalidatingRegion()}. Puts from transactions started after
* this timestamp are denied.
*/
private volatile long regionInvalidationTimestamp = Long.MIN_VALUE;
/**
* Number of ongoing concurrent invalidations.
*/
private int regionInvalidations = 0;
/**
* Allows propagation of current Session to callbacks invoked from interceptors
*/
private final ThreadLocal currentSession = new ThreadLocal();
/**
* Creates a new put from load validator instance.
*
* @param cache Cache instance on which to store pending put information.
*/
public PutFromLoadValidator(AdvancedCache cache) {
this( cache, cache.getCacheManager());
}
/**
* Creates a new put from load validator instance.
* @param cache Cache instance on which to store pending put information.
* @param cacheManager where to find a cache to store pending put information
*/
public PutFromLoadValidator(AdvancedCache cache, EmbeddedCacheManager cacheManager) {
Configuration cacheConfiguration = cache.getCacheConfiguration();
Configuration pendingPutsConfiguration = cacheManager.getCacheConfiguration(InfinispanRegionFactory.PENDING_PUTS_CACHE_NAME);
ConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
configurationBuilder.read(pendingPutsConfiguration);
configurationBuilder.dataContainer().keyEquivalence(cacheConfiguration.dataContainer().keyEquivalence());
String pendingPutsName = cache.getName() + "-" + InfinispanRegionFactory.PENDING_PUTS_CACHE_NAME;
cacheManager.defineConfiguration(pendingPutsName, configurationBuilder.build());
if (pendingPutsConfiguration.expiration() != null && pendingPutsConfiguration.expiration().maxIdle() > 0) {
this.expirationPeriod = pendingPutsConfiguration.expiration().maxIdle();
}
else {
throw new IllegalArgumentException("Pending puts cache needs to have maxIdle expiration set!");
}
CacheMode cacheMode = cache.getCacheConfiguration().clustering().cacheMode();
// Since we need to intercept both invalidations of entries that are in the cache and those
// that are not, we need to use custom interceptor, not listeners (which fire only for present entries).
NonTxPutFromLoadInterceptor nonTxPutFromLoadInterceptor = null;
if (cacheMode.isClustered()) {
if (!cacheMode.isInvalidation()) {
throw new IllegalArgumentException("PutFromLoadValidator in clustered caches requires invalidation mode.");
}
List interceptorChain = cache.getInterceptorChain();
log.debug("Interceptor chain was: " + interceptorChain);
int position = 0;
// add interceptor before uses exact match, not instanceof match
int invalidationPosition = 0;
int entryWrappingPosition = 0;
for (CommandInterceptor ci : interceptorChain) {
if (ci instanceof InvalidationInterceptor) {
invalidationPosition = position;
}
if (ci instanceof EntryWrappingInterceptor) {
entryWrappingPosition = position;
}
position++;
}
boolean transactional = cache.getCacheConfiguration().transaction().transactionMode().isTransactional();
if (transactional) {
// Note that invalidation does *NOT* acquire locks; therefore, we have to start invalidating before
// wrapping the entry, since if putFromLoad was invoked between wrap and beginInvalidatingKey, the invalidation
// would not commit the entry removal (as during wrap the entry was not in cache)
TxPutFromLoadInterceptor txPutFromLoadInterceptor = new TxPutFromLoadInterceptor(this, cache.getName());
cache.getComponentRegistry().registerComponent(txPutFromLoadInterceptor, TxPutFromLoadInterceptor.class);
cache.addInterceptor(txPutFromLoadInterceptor, entryWrappingPosition);
}
else {
cache.removeInterceptor(invalidationPosition);
NonTxInvalidationInterceptor nonTxInvalidationInterceptor = new NonTxInvalidationInterceptor(this);
cache.getComponentRegistry().registerComponent(nonTxInvalidationInterceptor, NonTxInvalidationInterceptor.class);
cache.addInterceptor(nonTxInvalidationInterceptor, invalidationPosition);
nonTxPutFromLoadInterceptor = new NonTxPutFromLoadInterceptor(this, cache.getName());
cache.getComponentRegistry().registerComponent(nonTxPutFromLoadInterceptor, NonTxPutFromLoadInterceptor.class);
cache.addInterceptor(nonTxPutFromLoadInterceptor, entryWrappingPosition);
}
log.debug("New interceptor chain is: " + cache.getInterceptorChain());
CacheCommandInitializer cacheCommandInitializer = cache.getComponentRegistry().getComponent(CacheCommandInitializer.class);
cacheCommandInitializer.addPutFromLoadValidator(cache.getName(), this);
}
this.cache = cache;
this.pendingPuts = cacheManager.getCache(pendingPutsName);
this.nonTxPutFromLoadInterceptor = nonTxPutFromLoadInterceptor;
}
/**
* This methods should be called only from tests; it removes existing validator from the cache structures
* in order to replace it with new one.
*
* @param cache
*/
public static void removeFromCache(AdvancedCache cache) {
cache.removeInterceptor(TxPutFromLoadInterceptor.class);
cache.removeInterceptor(NonTxPutFromLoadInterceptor.class);
for (Object i : cache.getInterceptorChain()) {
if (i instanceof NonTxInvalidationInterceptor) {
InvalidationInterceptor invalidationInterceptor = new InvalidationInterceptor();
cache.getComponentRegistry().registerComponent(invalidationInterceptor, InvalidationInterceptor.class);
cache.addInterceptorBefore(invalidationInterceptor, NonTxInvalidationInterceptor.class);
cache.removeInterceptor(NonTxInvalidationInterceptor.class);
break;
}
}
CacheCommandInitializer cci = cache.getComponentRegistry().getComponent(CacheCommandInitializer.class);
cci.removePutFromLoadValidator(cache.getName());
}
public void setCurrentSession(SessionImplementor session) {
currentSession.set(session);
}
public void resetCurrentSession() {
currentSession.remove();
}
/**
* Marker for lock acquired in {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)}
*/
public static abstract class Lock {
private Lock() {}
}
/**
* Acquire a lock giving the calling thread the right to put data in the
* cache for the given key.
*
* NOTE: A call to this method that returns true
* should always be matched with a call to {@link #releasePutFromLoadLock(Object, Lock)}.
*
*
* @param session
* @param key the key
*
* @param txTimestamp
* @return AcquiredLock if the lock is acquired and the cache put
* can proceed; null if the data should not be cached
*/
public Lock acquirePutFromLoadLock(SessionImplementor session, Object key, long txTimestamp) {
if (trace) {
log.tracef("acquirePutFromLoadLock(%s#%s, %d)", cache.getName(), key, txTimestamp);
}
boolean locked = false;
PendingPutMap pending = pendingPuts.get( key );
for (;;) {
try {
if (pending != null) {
locked = pending.acquireLock(100, TimeUnit.MILLISECONDS);
if (locked) {
boolean valid = false;
try {
if (pending.isRemoved()) {
// this deals with a race between retrieving the map from cache vs. removing that
// and locking the map
pending.releaseLock();
locked = false;
pending = null;
if (trace) {
log.tracef("Record removed when waiting for the lock.");
}
continue;
}
final PendingPut toCancel = pending.remove(session);
if (toCancel != null) {
valid = !toCancel.completed;
toCancel.completed = true;
}
else {
// this is a naked put
if (pending.hasInvalidator()) {
valid = false;
}
// we need this check since registerPendingPut (creating new pp) can get between invalidation
// and naked put caused by the invalidation
else if (pending.lastInvalidationEnd != Long.MIN_VALUE) {
// if this transaction started after last invalidation we can continue
valid = txTimestamp > pending.lastInvalidationEnd;
}
else {
valid = txTimestamp > regionInvalidationTimestamp;
}
}
return valid ? pending : null;
}
finally {
if (!valid && pending != null) {
pending.releaseLock();
locked = false;
}
if (trace) {
log.tracef("acquirePutFromLoadLock(%s#%s, %d) ended with %s, valid: %s", cache.getName(), key, txTimestamp, pending, valid);
}
}
}
else {
if (trace) {
log.tracef("acquirePutFromLoadLock(%s#%s, %d) failed to lock", cache.getName(), key, txTimestamp);
}
// oops, we have leaked record for this owner, but we don't want to wait here
return null;
}
}
else {
long regionInvalidationTimestamp = this.regionInvalidationTimestamp;
if (txTimestamp <= regionInvalidationTimestamp) {
if (trace) {
log.tracef("acquirePutFromLoadLock(%s#%s, %d) failed due to region invalidated at %d", cache.getName(), key, txTimestamp, regionInvalidationTimestamp);
}
return null;
}
else {
if (trace) {
log.tracef("Region invalidated at %d, this transaction started at %d", regionInvalidationTimestamp, txTimestamp);
}
}
PendingPut pendingPut = new PendingPut(session);
pending = new PendingPutMap(pendingPut);
PendingPutMap existing = pendingPuts.putIfAbsent(key, pending);
if (existing != null) {
pending = existing;
}
// continue in next loop with lock acquisition
}
}
catch (Throwable t) {
if (locked) {
pending.releaseLock();
}
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
}
else if (t instanceof Error) {
throw (Error) t;
}
else {
throw new RuntimeException(t);
}
}
}
}
/**
* Releases the lock previously obtained by a call to
* {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)}.
*
* @param key the key
*/
public void releasePutFromLoadLock(Object key, Lock lock) {
if (trace) {
log.tracef("releasePutFromLoadLock(%s#%s, %s)", cache.getName(), key, lock);
}
final PendingPutMap pending = (PendingPutMap) lock;
if ( pending != null ) {
if ( pending.canRemove() ) {
pending.setRemoved();
pendingPuts.remove( key, pending );
}
pending.releaseLock();
}
}
/**
* Invalidates all {@link #registerPendingPut(SessionImplementor, Object, long) previously registered pending puts} ensuring a subsequent call to
* {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)} will return false. This method will block until any
* concurrent thread that has {@link #acquirePutFromLoadLock(SessionImplementor, Object, long) acquired the putFromLoad lock} for the any key has
* released the lock. This allows the caller to be certain the putFromLoad will not execute after this method returns,
* possibly caching stale data.
*
* @return true if the invalidation was successful; false if a problem occured (which the
* caller should treat as an exception condition)
*/
public boolean beginInvalidatingRegion() {
if (trace) {
log.trace("Started invalidating region " + cache.getName());
}
boolean ok = true;
long now = System.currentTimeMillis();
// deny all puts until endInvalidatingRegion is called; at that time the region should be already
// in INVALID state, therefore all new requests should be blocked and ongoing should fail by timestamp
synchronized (this) {
regionInvalidationTimestamp = Long.MAX_VALUE;
regionInvalidations++;
}
try {
// Acquire the lock for each entry to ensure any ongoing
// work associated with it is completed before we return
// We cannot erase the map: if there was ongoing invalidation and we removed it, registerPendingPut
// started after that would have no way of finding out that the entity *is* invalidated (it was
// removed from the cache and now the DB is about to be updated).
for (Iterator it = pendingPuts.values().iterator(); it.hasNext(); ) {
PendingPutMap entry = it.next();
if (entry.acquireLock(60, TimeUnit.SECONDS)) {
try {
entry.invalidate(now);
}
finally {
entry.releaseLock();
}
}
else {
ok = false;
}
}
}
catch (Exception e) {
ok = false;
}
return ok;
}
/**
* Called when the region invalidation is finished.
*/
public void endInvalidatingRegion() {
synchronized (this) {
if (--regionInvalidations == 0) {
regionInvalidationTimestamp = System.currentTimeMillis();
if (trace) {
log.tracef("Finished invalidating region %s at %d", cache.getName(), regionInvalidationTimestamp);
}
}
else {
if (trace) {
log.tracef("Finished invalidating region %s, but there are %d ongoing invalidations", cache.getName(), regionInvalidations);
}
}
}
}
/**
* Notifies this validator that it is expected that a database read followed by a subsequent {@link
* #acquirePutFromLoadLock(SessionImplementor, Object, long)} call will occur. The intent is this method would be called following a cache miss
* wherein it is expected that a database read plus cache put will occur. Calling this method allows the validator to
* treat the subsequent acquirePutFromLoadLock as if the database read occurred when this method was
* invoked. This allows the validator to compare the timestamp of this call against the timestamp of subsequent removal
* notifications.
*
* @param session
* @param key key that will be used for subsequent cache put
* @param txTimestamp
*/
public void registerPendingPut(SessionImplementor session, Object key, long txTimestamp) {
long invalidationTimestamp = this.regionInvalidationTimestamp;
if (txTimestamp <= invalidationTimestamp) {
if (trace) {
log.tracef("registerPendingPut(%s#%s, %d) skipped due to region invalidation (%d)", cache.getName(), key, txTimestamp, invalidationTimestamp);
}
return;
}
final PendingPut pendingPut = new PendingPut( session );
final PendingPutMap pendingForKey = new PendingPutMap( pendingPut );
for (;;) {
final PendingPutMap existing = pendingPuts.putIfAbsent(key, pendingForKey);
if (existing != null) {
if (existing.acquireLock(10, TimeUnit.SECONDS)) {
try {
if (existing.isRemoved()) {
if (trace) {
log.tracef("Record removed when waiting for the lock.");
}
continue;
}
if (!existing.hasInvalidator()) {
existing.put(pendingPut);
}
}
finally {
existing.releaseLock();
}
if (trace) {
log.tracef("registerPendingPut(%s#%s, %d) ended with %s", cache.getName(), key, txTimestamp, existing);
}
}
else {
if (trace) {
log.tracef("registerPendingPut(%s#%s, %d) failed to acquire lock", cache.getName(), key, txTimestamp);
}
// Can't get the lock; when we come back we'll be a "naked put"
}
}
else {
if (trace) {
log.tracef("registerPendingPut(%s#%s, %d) registered using putIfAbsent: %s", cache.getName(), key, txTimestamp, pendingForKey);
}
}
return;
}
}
/**
* Invalidates any {@link #registerPendingPut(SessionImplementor, Object, long) previously registered pending puts}
* and disables further registrations ensuring a subsequent call to {@link #acquirePutFromLoadLock(SessionImplementor, Object, long)}
* will return false. This method will block until any concurrent thread that has
* {@link #acquirePutFromLoadLock(SessionImplementor, Object, long) acquired the putFromLoad lock} for the given key
* has released the lock. This allows the caller to be certain the putFromLoad will not execute after this method
* returns, possibly caching stale data.
* After this transaction completes, {@link #endInvalidatingKey(Object, Object)} needs to be called }
*
* @param key key identifying data whose pending puts should be invalidated
*
* @return true if the invalidation was successful; false if a problem occured (which the
* caller should treat as an exception condition)
*/
public boolean beginInvalidatingKey(Object lockOwner, Object key) {
return beginInvalidatingWithPFER(lockOwner, key, null);
}
public boolean beginInvalidatingWithPFER(Object lockOwner, Object key, Object valueForPFER) {
for (;;) {
PendingPutMap pending = new PendingPutMap(null);
PendingPutMap prev = pendingPuts.putIfAbsent(key, pending);
if (prev != null) {
pending = prev;
}
if (pending.acquireLock(60, TimeUnit.SECONDS)) {
try {
if (pending.isRemoved()) {
if (trace) {
log.tracef("Record removed when waiting for the lock.");
}
continue;
}
long now = System.currentTimeMillis();
pending.invalidate(now);
pending.addInvalidator(lockOwner, valueForPFER, now);
}
finally {
pending.releaseLock();
}
if (trace) {
log.tracef("beginInvalidatingKey(%s#%s, %s) ends with %s", cache.getName(), key, lockOwnerToString(lockOwner), pending);
}
return true;
}
else {
log.tracef("beginInvalidatingKey(%s#%s, %s) failed to acquire lock", cache.getName(), key, lockOwnerToString(lockOwner));
return false;
}
}
}
public boolean endInvalidatingKey(Object lockOwner, Object key) {
return endInvalidatingKey(lockOwner, key, false);
}
/**
* Called after the transaction completes, allowing caching of entries. It is possible that this method
* is called without previous invocation of {@link #beginInvalidatingKey(Object, Object)}, then it should be a no-op.
*
* @param lockOwner owner of the invalidation - transaction or thread
* @param key
* @return
*/
public boolean endInvalidatingKey(Object lockOwner, Object key, boolean doPFER) {
PendingPutMap pending = pendingPuts.get(key);
if (pending == null) {
if (trace) {
log.tracef("endInvalidatingKey(%s#%s, %s) could not find pending puts", cache.getName(), key, lockOwnerToString(lockOwner));
}
return true;
}
if (pending.acquireLock(60, TimeUnit.SECONDS)) {
try {
long now = System.currentTimeMillis();
pending.removeInvalidator(lockOwner, key, now, doPFER);
// we can't remove the pending put yet because we wait for naked puts
// pendingPuts should be configured with maxIdle time so won't have memory leak
return true;
}
finally {
pending.releaseLock();
if (trace) {
log.tracef("endInvalidatingKey(%s#%s, %s) ends with %s", cache.getName(), key, lockOwnerToString(lockOwner), pending);
}
}
}
else {
if (trace) {
log.tracef("endInvalidatingKey(%s#%s, %s) failed to acquire lock", cache.getName(), key, lockOwnerToString(lockOwner));
}
return false;
}
}
public Object registerRemoteInvalidations(Object[] keys) {
SessionImplementor session = currentSession.get();
TransactionCoordinator transactionCoordinator = session == null ? null : session.getTransactionCoordinator();
if (transactionCoordinator != null) {
if (trace) {
log.tracef("Registering lock owner %s for %s: %s", lockOwnerToString(session), cache.getName(), Arrays.toString(keys));
}
InvalidationSynchronization sync = new InvalidationSynchronization(nonTxPutFromLoadInterceptor, keys);
transactionCoordinator.getLocalSynchronizations().registerSynchronization(sync);
return sync.uuid;
}
// evict() command is not executed in session context
return null;
}
// ---------------------------------------------------------------- Private
// we can't use SessionImpl.toString() concurrently
private static String lockOwnerToString(Object lockOwner) {
return lockOwner instanceof SessionImplementor ? "Session#" + lockOwner.hashCode() : lockOwner.toString();
}
/**
* Lazy-initialization map for PendingPut. Optimized for the expected usual case where only a
* single put is pending for a given key.
*
* This class is NOT THREAD SAFE. All operations on it must be performed with the lock held.
*/
private class PendingPutMap extends Lock {
// Number of pending puts which trigger garbage collection
private static final int GC_THRESHOLD = 10;
private PendingPut singlePendingPut;
private Map fullMap;
private final java.util.concurrent.locks.Lock lock = new ReentrantLock();
private Invalidator singleInvalidator;
private Map invalidators;
private long lastInvalidationEnd = Long.MIN_VALUE;
private boolean removed = false;
PendingPutMap(PendingPut singleItem) {
this.singlePendingPut = singleItem;
}
// toString should be called only for debugging purposes
public String toString() {
if (lock.tryLock()) {
try {
StringBuilder sb = new StringBuilder();
sb.append("{ PendingPuts=");
if (singlePendingPut == null) {
if (fullMap == null) {
sb.append("[]");
}
else {
sb.append(fullMap.values());
}
}
else {
sb.append('[').append(singlePendingPut).append(']');
}
sb.append(", Invalidators=");
if (singleInvalidator == null) {
if (invalidators == null) {
sb.append("[]");
}
else {
sb.append(invalidators.values());
}
}
else {
sb.append('[').append(singleInvalidator).append(']');
}
sb.append(", LastInvalidationEnd=");
if (lastInvalidationEnd == Long.MIN_VALUE) {
sb.append("");
}
else {
sb.append(lastInvalidationEnd);
}
return sb.append(", Removed=").append(removed).append("}").toString();
}
finally {
lock.unlock();
}
}
else {
return "PendingPutMap: ";
}
}
public void put(PendingPut pendingPut) {
if ( singlePendingPut == null ) {
if ( fullMap == null ) {
// initial put
singlePendingPut = pendingPut;
}
else {
fullMap.put( pendingPut.owner, pendingPut );
if (fullMap.size() >= GC_THRESHOLD) {
gc();
}
}
}
else {
// 2nd put; need a map
fullMap = new HashMap( 4 );
fullMap.put( singlePendingPut.owner, singlePendingPut );
singlePendingPut = null;
fullMap.put( pendingPut.owner, pendingPut );
}
}
public PendingPut remove(Object ownerForPut) {
PendingPut removed = null;
if ( fullMap == null ) {
if ( singlePendingPut != null
&& singlePendingPut.owner.equals( ownerForPut ) ) {
removed = singlePendingPut;
singlePendingPut = null;
}
}
else {
removed = fullMap.remove( ownerForPut );
}
return removed;
}
public int size() {
return fullMap == null ? (singlePendingPut == null ? 0 : 1)
: fullMap.size();
}
public boolean acquireLock(long time, TimeUnit unit) {
try {
return lock.tryLock( time, unit );
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
return false;
}
}
public void releaseLock() {
lock.unlock();
}
public void invalidate(long now) {
if ( singlePendingPut != null ) {
if (singlePendingPut.invalidate(now, expirationPeriod)) {
singlePendingPut = null;
}
}
else if ( fullMap != null ) {
for ( Iterator it = fullMap.values().iterator(); it.hasNext(); ) {
PendingPut pp = it.next();
if (pp.invalidate(now, expirationPeriod)) {
it.remove();
}
}
}
}
/**
* Running {@link #gc()} is important when the key is regularly queried but it is not
* present in DB. In such case, the putFromLoad would not be called at all and we would
* leak pending puts. Cache expiration should handle the case when the pending puts
* are not accessed frequently; when these are accessed, we have to do the housekeeping
* internally to prevent unlimited growth of the map.
* The pending puts will get their timestamps when the map reaches {@link #GC_THRESHOLD}
* entries; after expiration period these will be removed completely either through
* invalidation or when we try to register next pending put.
*/
private void gc() {
assert fullMap != null;
long now = System.currentTimeMillis();
for ( Iterator it = fullMap.values().iterator(); it.hasNext(); ) {
PendingPut pp = it.next();
if (pp.gc(now, expirationPeriod)) {
it.remove();
}
}
}
public void addInvalidator(Object owner, Object valueForPFER, long now) {
assert owner != null;
if (invalidators == null) {
if (singleInvalidator == null) {
singleInvalidator = new Invalidator(owner, now, valueForPFER);
put(new PendingPut(owner));
}
else {
if (singleInvalidator.registeredTimestamp + expirationPeriod < now) {
// override leaked invalidator
singleInvalidator = new Invalidator(owner, now, valueForPFER);
put(new PendingPut(owner));
}
invalidators = new HashMap();
invalidators.put(singleInvalidator.owner, singleInvalidator);
// with multiple invalidations the PFER must not be executed
invalidators.put(owner, new Invalidator(owner, now, null));
singleInvalidator = null;
}
}
else {
long allowedRegistration = now - expirationPeriod;
// remove leaked invalidators
for (Iterator it = invalidators.values().iterator(); it.hasNext(); ) {
if (it.next().registeredTimestamp < allowedRegistration) {
it.remove();
}
}
// With multiple invalidations in parallel we don't know the order in which
// the writes were applied into DB and therefore we can't update the cache
// with the most recent value.
if (invalidators.isEmpty()) {
put(new PendingPut(owner));
}
else {
valueForPFER = null;
}
invalidators.put(owner, new Invalidator(owner, now, valueForPFER));
}
}
public boolean hasInvalidator() {
return singleInvalidator != null || (invalidators != null && !invalidators.isEmpty());
}
// Debug introspection method, do not use in production code!
public Collection getInvalidators() {
lock.lock();
try {
if (singleInvalidator != null) {
return Collections.singleton(singleInvalidator);
}
else if (invalidators != null) {
return new ArrayList(invalidators.values());
}
else {
return Collections.EMPTY_LIST;
}
}
finally {
lock.unlock();
}
}
public void removeInvalidator(Object owner, Object key, long now, boolean doPFER) {
if (invalidators == null) {
if (singleInvalidator != null && singleInvalidator.owner.equals(owner)) {
pferValueIfNeeded(owner, key, singleInvalidator.valueForPFER, doPFER);
singleInvalidator = null;
}
}
else {
Invalidator invalidator = invalidators.remove(owner);
if (invalidator != null) {
pferValueIfNeeded(owner, key, invalidator.valueForPFER, doPFER);
}
}
lastInvalidationEnd = Math.max(lastInvalidationEnd, now);
}
private void pferValueIfNeeded(Object owner, Object key, Object valueForPFER, boolean doPFER) {
if (valueForPFER != null) {
PendingPut pendingPut = remove(owner);
if (doPFER && pendingPut != null && !pendingPut.completed) {
cache.putForExternalRead(key, valueForPFER);
}
}
}
public boolean canRemove() {
return size() == 0 && !hasInvalidator() && lastInvalidationEnd == Long.MIN_VALUE;
}
public void setRemoved() {
removed = true;
}
public boolean isRemoved() {
return removed;
}
}
private static class PendingPut {
private final Object owner;
private boolean completed;
// the timestamp is not filled during registration in order to avoid expensive currentTimeMillis() calls
private long registeredTimestamp = Long.MIN_VALUE;
private PendingPut(Object owner) {
this.owner = owner;
}
public String toString() {
// we can't use SessionImpl.toString() concurrently
return (completed ? "C@" : "R@") + lockOwnerToString(owner);
}
public boolean invalidate(long now, long expirationPeriod) {
completed = true;
return gc(now, expirationPeriod);
}
public boolean gc(long now, long expirationPeriod) {
if (registeredTimestamp == Long.MIN_VALUE) {
registeredTimestamp = now;
}
else if (registeredTimestamp + expirationPeriod < now){
return true; // this is a leaked pending put
}
return false;
}
}
private static class Invalidator {
private final Object owner;
private final long registeredTimestamp;
private final Object valueForPFER;
private Invalidator(Object owner, long registeredTimestamp, Object valueForPFER) {
this.owner = owner;
this.registeredTimestamp = registeredTimestamp;
this.valueForPFER = valueForPFER;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("{");
sb.append("Owner=").append(lockOwnerToString(owner));
sb.append(", Timestamp=").append(registeredTimestamp);
sb.append('}');
return sb.toString();
}
}
}
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