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Manages datastore contention with exponential backoff [v5] #462

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Manages datastore contention with exponential backoff [v5] #462

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73b7969
Add exponential backoff
frew Sep 7, 2018
ae8a37d
Add default try limit
nparrag Feb 12, 2020
70782a0
Let the caller handle ConcurrentModificationException when we got Int…
nparrag Feb 12, 2020
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2 changes: 1 addition & 1 deletion src/main/java/com/googlecode/objectify/impl/ObjectifyImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -208,7 +208,7 @@ public Void run() {
*/
@Override
public <R> R transactNew(Work<R> work) {
return this.transactNew(Integer.MAX_VALUE, work);
return this.transactNew(Transactor.DEFAULT_TRY_LIMIT, work);
}

/* (non-Javadoc)
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3 changes: 3 additions & 0 deletions src/main/java/com/googlecode/objectify/impl/Transactor.java
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Expand Up @@ -12,6 +12,9 @@
*/
abstract public class Transactor<O extends Objectify>
{
// Limit default number of retries to something high but non-infinite
public static final int DEFAULT_TRY_LIMIT = 200;

/** Our session */
protected Session session;

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9 changes: 8 additions & 1 deletion src/main/java/com/googlecode/objectify/impl/TransactorNo.java
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Expand Up @@ -82,7 +82,7 @@ public <R> R execute(ObjectifyImpl<O> parent, TxnType txnType, Work<R> work) {
*/
@Override
public <R> R transact(ObjectifyImpl<O> parent, Work<R> work) {
return this.transactNew(parent, Integer.MAX_VALUE, work);
return this.transactNew(parent, DEFAULT_TRY_LIMIT, work);
}

/* (non-Javadoc)
Expand All @@ -91,6 +91,7 @@ public <R> R transact(ObjectifyImpl<O> parent, Work<R> work) {
@Override
public <R> R transactNew(ObjectifyImpl<O> parent, int limitTries, Work<R> work) {
Preconditions.checkArgument(limitTries >= 1);
final int ORIGINAL_TRIES = limitTries;

while (true) {
try {
Expand All @@ -102,6 +103,12 @@ public <R> R transactNew(ObjectifyImpl<O> parent, int limitTries, Work<R> work)

if (log.isLoggable(Level.FINEST))
log.log(Level.FINEST, "Details of optimistic concurrency failure", ex);
try {
// Do increasing backoffs with randomness
Thread.sleep(Math.min(10000, (long) (0.5 * Math.random() + 0.5) * 200 * (ORIGINAL_TRIES - limitTries + 2)));
} catch (InterruptedException ignored) {
throw ex;
}
} else {
throw ex;
}
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2 changes: 1 addition & 1 deletion src/main/java/com/googlecode/objectify/impl/TransactorYes.java
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Expand Up @@ -86,7 +86,7 @@ public <R> R execute(ObjectifyImpl<O> parent, TxnType txnType, Work<R> work) {
throw new IllegalStateException("MANDATORY transaction but no transaction present");

case REQUIRES_NEW:
return transactNew(parent, Integer.MAX_VALUE, work);
return transactNew(parent, DEFAULT_TRY_LIMIT, work);

default:
throw new IllegalStateException("Impossible, some unknown txn type");
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