import akka.serialization.Serialization;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
-import com.google.common.cache.Cache;
-import com.google.common.cache.CacheBuilder;
-import com.google.common.cache.RemovalCause;
-import com.google.common.cache.RemovalListener;
-import com.google.common.cache.RemovalNotification;
+import com.google.common.base.Stopwatch;
+import java.util.HashMap;
+import java.util.Iterator;
import java.util.LinkedList;
+import java.util.Map;
import java.util.Queue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
ShardDataTreeCohort decorate(String transactionID, ShardDataTreeCohort actual);
}
- private final Cache<String, CohortEntry> cohortCache;
+ private final Map<String, CohortEntry> cohortCache = new HashMap<>();
private CohortEntry currentCohortEntry;
private final ShardDataTree dataTree;
- private final Queue<CohortEntry> queuedCohortEntries;
+ // We use a LinkedList here to avoid synchronization overhead with concurrent queue impls
+ // since this should only be accessed on the shard's dispatcher.
+ private final Queue<CohortEntry> queuedCohortEntries = new LinkedList<>();
private int queueCapacity;
private final String name;
- private final RemovalListener<String, CohortEntry> cacheRemovalListener =
- new RemovalListener<String, CohortEntry>() {
- @Override
- public void onRemoval(RemovalNotification<String, CohortEntry> notification) {
- if(notification.getCause() == RemovalCause.EXPIRED) {
- log.warn("{}: Transaction {} was timed out of the cache", name, notification.getKey());
- }
- }
- };
+ private final long cacheExpiryTimeoutInMillis;
// This is a hook for unit tests to replace or decorate the DOMStoreThreePhaseCommitCohorts.
private CohortDecorator cohortDecorator;
private ReadyTransactionReply readyTransactionReply;
public ShardCommitCoordinator(ShardDataTree dataTree,
- long cacheExpiryTimeoutInSec, int queueCapacity, ActorRef shardActor, Logger log, String name) {
+ long cacheExpiryTimeoutInMillis, int queueCapacity, ActorRef shardActor, Logger log, String name) {
this.queueCapacity = queueCapacity;
this.log = log;
this.name = name;
this.dataTree = Preconditions.checkNotNull(dataTree);
-
- cohortCache = CacheBuilder.newBuilder().expireAfterAccess(cacheExpiryTimeoutInSec, TimeUnit.SECONDS).
- removalListener(cacheRemovalListener).build();
-
- // We use a LinkedList here to avoid synchronization overhead with concurrent queue impls
- // since this should only be accessed on the shard's dispatcher.
- queuedCohortEntries = new LinkedList<>();
+ this.cacheExpiryTimeoutInMillis = cacheExpiryTimeoutInMillis;
}
public void setQueueCapacity(int queueCapacity) {
return readyTransactionReply;
}
+ private boolean queueCohortEntry(CohortEntry cohortEntry, ActorRef sender, Shard shard) {
+ if(queuedCohortEntries.size() < queueCapacity) {
+ queuedCohortEntries.offer(cohortEntry);
+ return true;
+ } else {
+ cohortCache.remove(cohortEntry.getTransactionID());
+
+ RuntimeException ex = new RuntimeException(
+ String.format("%s: Could not enqueue transaction %s - the maximum commit queue"+
+ " capacity %d has been reached.",
+ name, cohortEntry.getTransactionID(), queueCapacity));
+ log.error(ex.getMessage());
+ sender.tell(new Status.Failure(ex), shard.self());
+ return false;
+ }
+ }
+
/**
* This method is called to ready a transaction that was prepared by ShardTransaction actor. It caches
* the prepared cohort entry for the given transactions ID in preparation for the subsequent 3-phase commit.
(MutableCompositeModification) ready.getModification());
cohortCache.put(ready.getTransactionID(), cohortEntry);
+ if(!queueCohortEntry(cohortEntry, sender, shard)) {
+ return;
+ }
+
if(ready.getTxnClientVersion() < DataStoreVersions.LITHIUM_VERSION) {
// Return our actor path as we'll handle the three phase commit except if the Tx client
// version < Helium-1 version which means the Tx was initiated by a base Helium version node.
*
* @throws ExecutionException if an error occurs loading the cache
*/
- boolean handleBatchedModifications(BatchedModifications batched, ActorRef sender, Shard shard)
+ void handleBatchedModifications(BatchedModifications batched, ActorRef sender, Shard shard)
throws ExecutionException {
- CohortEntry cohortEntry = cohortCache.getIfPresent(batched.getTransactionID());
+ CohortEntry cohortEntry = cohortCache.get(batched.getTransactionID());
if(cohortEntry == null) {
cohortEntry = new CohortEntry(batched.getTransactionID(),
dataTree.newReadWriteTransaction(batched.getTransactionID(),
cohortEntry.applyModifications(batched.getModifications());
if(batched.isReady()) {
+ if(!queueCohortEntry(cohortEntry, sender, shard)) {
+ return;
+ }
+
if(log.isDebugEnabled()) {
log.debug("{}: Readying Tx {}, client version {}", name,
batched.getTransactionID(), batched.getVersion());
} else {
sender.tell(new BatchedModificationsReply(batched.getModifications().size()), shard.self());
}
-
- return batched.isReady();
}
/**
final CohortEntry cohortEntry = new CohortEntry(message.getTransactionID(), cohort);
cohortCache.put(message.getTransactionID(), cohortEntry);
cohortEntry.setDoImmediateCommit(message.isDoCommitOnReady());
+
+ if(!queueCohortEntry(cohortEntry, sender, shard)) {
+ return;
+ }
+
log.debug("{}: Applying local modifications for Tx {}", name, message.getTransactionID());
if (message.isDoCommitOnReady()) {
private void handleCanCommit(CohortEntry cohortEntry) {
String transactionID = cohortEntry.getTransactionID();
- if(log.isDebugEnabled()) {
- log.debug("{}: Processing canCommit for transaction {} for shard {}",
- name, transactionID, cohortEntry.getShard().self().path());
- }
+ cohortEntry.updateLastAccessTime();
if(currentCohortEntry != null) {
- // There's already a Tx commit in progress - attempt to queue this entry to be
- // committed after the current Tx completes.
- log.debug("{}: Transaction {} is already in progress - queueing transaction {}",
- name, currentCohortEntry.getTransactionID(), transactionID);
+ // There's already a Tx commit in progress so we can't process this entry yet - but it's in the
+ // queue and will get processed after all prior entries complete.
- if(queuedCohortEntries.size() < queueCapacity) {
- queuedCohortEntries.offer(cohortEntry);
- } else {
- removeCohortEntry(transactionID);
-
- RuntimeException ex = new RuntimeException(
- String.format("%s: Could not enqueue transaction %s - the maximum commit queue"+
- " capacity %d has been reached.",
- name, transactionID, queueCapacity));
- log.error(ex.getMessage());
- cohortEntry.getReplySender().tell(new Status.Failure(ex), cohortEntry.getShard().self());
+ if(log.isDebugEnabled()) {
+ log.debug("{}: Commit for Tx {} already in progress - skipping canCommit for {} for now",
+ name, currentCohortEntry.getTransactionID(), transactionID);
}
- } else {
- // No Tx commit currently in progress - make this the current entry and proceed with
- // canCommit.
- cohortEntry.updateLastAccessTime();
- currentCohortEntry = cohortEntry;
- doCanCommit(cohortEntry);
+ return;
+ }
+
+ // No Tx commit currently in progress - check if this entry is the next one in the queue, If so make
+ // it the current entry and proceed with canCommit.
+ // Purposely checking reference equality here.
+ if(queuedCohortEntries.peek() == cohortEntry) {
+ currentCohortEntry = queuedCohortEntries.poll();
+ doCanCommit(currentCohortEntry);
+ } else {
+ if(log.isDebugEnabled()) {
+ log.debug("{}: Tx {} is the next pending canCommit - skipping {} for now",
+ name, queuedCohortEntries.peek().getTransactionID(), transactionID);
+ }
}
}
public void handleCanCommit(String transactionID, final ActorRef sender, final Shard shard) {
// Lookup the cohort entry that was cached previously (or should have been) by
// transactionReady (via the ForwardedReadyTransaction message).
- final CohortEntry cohortEntry = cohortCache.getIfPresent(transactionID);
+ final CohortEntry cohortEntry = cohortCache.get(transactionID);
if(cohortEntry == null) {
// Either canCommit was invoked before ready(shouldn't happen) or a long time passed
// between canCommit and ready and the entry was expired from the cache.
}
private void doCanCommit(final CohortEntry cohortEntry) {
-
boolean canCommit = false;
try {
// We block on the future here so we don't have to worry about possibly accessing our
// currently uses a same thread executor anyway.
canCommit = cohortEntry.getCohort().canCommit().get();
+ log.debug("{}: canCommit for {}: {}", name, cohortEntry.getTransactionID(), canCommit);
+
if(cohortEntry.isDoImmediateCommit()) {
if(canCommit) {
doCommit(cohortEntry);
CanCommitTransactionReply.NO.toSerializable(), cohortEntry.getShard().self());
}
} catch (Exception e) {
- log.debug("{}: An exception occurred during canCommit: {}", name, e);
+ log.debug("{}: An exception occurred during canCommit", name, e);
Throwable failure = e;
if(e instanceof ExecutionException) {
return false;
}
+ cohortEntry.setReplySender(sender);
return doCommit(cohortEntry);
}
}
public CohortEntry getAndRemoveCohortEntry(String transactionID) {
- CohortEntry cohortEntry = cohortCache.getIfPresent(transactionID);
- cohortCache.invalidate(transactionID);
- return cohortEntry;
- }
-
- public void removeCohortEntry(String transactionID) {
- cohortCache.invalidate(transactionID);
+ return cohortCache.remove(transactionID);
}
public boolean isCurrentTransaction(String transactionID) {
*/
public void currentTransactionComplete(String transactionID, boolean removeCohortEntry) {
if(removeCohortEntry) {
- removeCohortEntry(transactionID);
+ cohortCache.remove(transactionID);
}
if(isCurrentTransaction(transactionID)) {
- // Dequeue the next cohort entry waiting in the queue.
- currentCohortEntry = queuedCohortEntries.poll();
- if(currentCohortEntry != null) {
- currentCohortEntry.updateLastAccessTime();
- doCanCommit(currentCohortEntry);
+ currentCohortEntry = null;
+
+ log.debug("{}: currentTransactionComplete: {}", name, transactionID);
+
+ maybeProcessNextCohortEntry();
+ }
+ }
+
+ private void maybeProcessNextCohortEntry() {
+ // Check if there's a next cohort entry waiting in the queue and if it is ready to commit. Also
+ // clean out expired entries.
+ Iterator<CohortEntry> iter = queuedCohortEntries.iterator();
+ while(iter.hasNext()) {
+ CohortEntry next = iter.next();
+ if(next.isReadyToCommit()) {
+ if(currentCohortEntry == null) {
+ if(log.isDebugEnabled()) {
+ log.debug("{}: Next entry to canCommit {}", name, next);
+ }
+
+ iter.remove();
+ currentCohortEntry = next;
+ currentCohortEntry.updateLastAccessTime();
+ doCanCommit(currentCohortEntry);
+ }
+
+ break;
+ } else if(next.isExpired(cacheExpiryTimeoutInMillis)) {
+ log.warn("{}: canCommit for transaction {} was not received within {} ms - entry removed from cache",
+ name, next.getTransactionID(), cacheExpiryTimeoutInMillis);
+
+ iter.remove();
+ cohortCache.remove(next.getTransactionID());
+ } else {
+ break;
}
}
}
+ void cleanupExpiredCohortEntries() {
+ maybeProcessNextCohortEntry();
+ }
+
@VisibleForTesting
void setCohortDecorator(CohortDecorator cohortDecorator) {
this.cohortDecorator = cohortDecorator;
}
-
static class CohortEntry {
private final String transactionID;
private ShardDataTreeCohort cohort;
private final ReadWriteShardDataTreeTransaction transaction;
private ActorRef replySender;
private Shard shard;
- private long lastAccessTime;
private boolean doImmediateCommit;
+ private final Stopwatch lastAccessTimer = Stopwatch.createStarted();
CohortEntry(String transactionID, ReadWriteShardDataTreeTransaction transaction) {
this.transaction = Preconditions.checkNotNull(transaction);
}
void updateLastAccessTime() {
- lastAccessTime = System.currentTimeMillis();
- }
-
- long getLastAccessTime() {
- return lastAccessTime;
+ lastAccessTimer.reset();
+ lastAccessTimer.start();
}
String getTransactionID() {
}
}
+ boolean isReadyToCommit() {
+ return replySender != null;
+ }
+
+ boolean isExpired(long expireTimeInMillis) {
+ return lastAccessTimer.elapsed(TimeUnit.MILLISECONDS) >= expireTimeInMillis;
+ }
+
boolean isDoImmediateCommit() {
return doImmediateCommit;
}
void setShard(Shard shard) {
this.shard = shard;
}
+
+ @Override
+ public String toString() {
+ StringBuilder builder = new StringBuilder();
+ builder.append("CohortEntry [transactionID=").append(transactionID).append(", doImmediateCommit=")
+ .append(doImmediateCommit).append("]");
+ return builder.toString();
+ }
}
}
Code Review / controller.git / blobdiff