304 lines
9.4 KiB
Java
304 lines
9.4 KiB
Java
package se.scalablesolutions.akka.stm;
|
|
|
|
import org.multiverse.api.Stm;
|
|
import org.multiverse.api.Transaction;
|
|
import org.multiverse.api.TransactionStatus;
|
|
import org.multiverse.api.exceptions.CommitFailureException;
|
|
import org.multiverse.api.exceptions.LoadException;
|
|
import org.multiverse.api.exceptions.RetryError;
|
|
import org.multiverse.api.exceptions.TooManyRetriesException;
|
|
import org.multiverse.utils.GlobalStmInstance;
|
|
import static org.multiverse.utils.TransactionThreadLocal.getThreadLocalTransaction;
|
|
import static org.multiverse.utils.TransactionThreadLocal.setThreadLocalTransaction;
|
|
|
|
/**
|
|
* A Template that handles the boilerplate code for transactions. A transaction will be placed if
|
|
* none is available around a section and if all goes right, commits at the end.
|
|
* <p/>
|
|
* example:
|
|
* <pre>
|
|
* new AtomicTemplate(){
|
|
* Object execute(Transaction t){
|
|
* queue.push(1);
|
|
* return null;
|
|
* }
|
|
* }.execute();
|
|
* </pre>
|
|
* <p/>
|
|
* It could also be that the transaction is retried (e.g. caused by optimistic locking failures). This is also a
|
|
* task for template. In the future this retry behavior will be customizable.
|
|
* <p/>
|
|
* If a transaction already is available on the TransactionThreadLocal, no new transaction is started
|
|
* and essentially the whole AtomicTemplate is ignored.
|
|
* <p/>
|
|
* If no transaction is available on the TransactionThreadLocal, a new one will be created and used
|
|
* during the execution of the AtomicTemplate and will be removed once the AtomicTemplate finishes.
|
|
* <p/>
|
|
* All uncaught throwable's lead to a rollback of the transaction.
|
|
* <p/>
|
|
* AtomicTemplates are not thread-safe to use.
|
|
* <p/>
|
|
* AtomicTemplates can completely work without threadlocals. See the
|
|
* {@link AtomicTemplate#AtomicTemplate(org.multiverse.api.Stm ,String, boolean, boolean, int)} for more information.
|
|
*
|
|
* @author Peter Veentjer
|
|
*/
|
|
public abstract class AtomicTemplate<E> {
|
|
private final Stm stm;
|
|
private final boolean ignoreThreadLocalTransaction;
|
|
private final int retryCount;
|
|
private final boolean readonly;
|
|
private int attemptCount;
|
|
private final String familyName;
|
|
|
|
/**
|
|
* Creates a new AtomicTemplate that uses the STM stored in the GlobalStm and
|
|
* works the the {@link org.multiverse.utils.TransactionThreadLocal}.
|
|
*/
|
|
public AtomicTemplate() {
|
|
this(GlobalStmInstance.get());
|
|
}
|
|
|
|
public AtomicTemplate(boolean readonly) {
|
|
this(GlobalStmInstance.get(), null, false, readonly, Integer.MAX_VALUE);
|
|
}
|
|
|
|
/**
|
|
* Creates a new AtomicTemplate using the provided stm. The transaction used
|
|
* is stores/retrieved from the {@link org.multiverse.utils.TransactionThreadLocal}.
|
|
*
|
|
* @param stm the stm to use for transactions.
|
|
* @throws NullPointerException if stm is null.
|
|
*/
|
|
public AtomicTemplate(Stm stm) {
|
|
this(stm, null, false, false, Integer.MAX_VALUE);
|
|
}
|
|
|
|
public AtomicTemplate(String familyName, boolean readonly, int retryCount) {
|
|
this(GlobalStmInstance.get(), familyName, false, readonly, retryCount);
|
|
}
|
|
|
|
/**
|
|
* Creates a new AtomicTemplate that uses the provided STM. This method is provided
|
|
* to make Multiverse easy to integrate with environment that don't want to depend on
|
|
* threadlocals.
|
|
*
|
|
* @param stm the stm to use for transactions.
|
|
* @param ignoreThreadLocalTransaction true if this Template should completely ignore
|
|
* the ThreadLocalTransaction. This is useful for using the AtomicTemplate in other
|
|
* environments that don't want to depend on threadlocals but do want to use the AtomicTemplate.
|
|
* @throws NullPointerException if stm is null.
|
|
*/
|
|
public AtomicTemplate(Stm stm, String familyName, boolean ignoreThreadLocalTransaction, boolean readonly, int retryCount) {
|
|
if (stm == null) {
|
|
throw new NullPointerException();
|
|
}
|
|
if (retryCount < 0) {
|
|
throw new IllegalArgumentException();
|
|
}
|
|
this.stm = stm;
|
|
this.ignoreThreadLocalTransaction = ignoreThreadLocalTransaction;
|
|
this.readonly = readonly;
|
|
this.retryCount = retryCount;
|
|
this.familyName = familyName;
|
|
}
|
|
|
|
public String getFamilyName() {
|
|
return familyName;
|
|
}
|
|
|
|
/**
|
|
* Returns the current attempt. Value will always be larger than zero and increases
|
|
* everytime the transaction needs to be retried.
|
|
*
|
|
* @return the current attempt count.
|
|
*/
|
|
public final int getAttemptCount() {
|
|
return attemptCount;
|
|
}
|
|
|
|
/**
|
|
* Returns the number of retries that this AtomicTemplate is allowed to do. The returned
|
|
* value will always be equal or larger than 0.
|
|
*
|
|
* @return the number of retries.
|
|
*/
|
|
public final int getRetryCount() {
|
|
return retryCount;
|
|
}
|
|
|
|
/**
|
|
* Returns the {@link Stm} used by this AtomicTemplate to execute transactions on.
|
|
*
|
|
* @return the Stm used by this AtomicTemplate.
|
|
*/
|
|
public final Stm getStm() {
|
|
return stm;
|
|
}
|
|
|
|
/**
|
|
* Check if this AtomicTemplate ignores the ThreadLocalTransaction.
|
|
*
|
|
* @return true if this AtomicTemplate ignores the ThreadLocalTransaction, false otherwise.
|
|
*/
|
|
public final boolean isIgnoreThreadLocalTransaction() {
|
|
return ignoreThreadLocalTransaction;
|
|
}
|
|
|
|
/**
|
|
* Checks if this AtomicTemplate executes readonly transactions.
|
|
*
|
|
* @return true if it executes readonly transactions, false otherwise.
|
|
*/
|
|
public final boolean isReadonly() {
|
|
return readonly;
|
|
}
|
|
|
|
/**
|
|
* This is the method that needs to be implemented.
|
|
*
|
|
* @param t the transaction used for this execution.
|
|
* @return the result of the execution.
|
|
* @throws Exception the Exception thrown
|
|
*/
|
|
public abstract E execute(Transaction t) throws Exception;
|
|
|
|
/**
|
|
* This is the method can be overridden to do pre-start tasks.
|
|
*/
|
|
public void preStart() {
|
|
}
|
|
|
|
/**
|
|
* This is the method can be overridden to do post-start tasks.
|
|
*
|
|
* @param t the transaction used for this execution.
|
|
*/
|
|
public void postStart(Transaction t) {
|
|
}
|
|
|
|
/**
|
|
* This is the method can be overridden to do pre-commit tasks.
|
|
*/
|
|
public void preCommit() {
|
|
}
|
|
|
|
/**
|
|
* This is the method can be overridden to do post-commit tasks.
|
|
*/
|
|
public void postCommit() {
|
|
}
|
|
|
|
/**
|
|
* Executes the template.
|
|
*
|
|
* @return the result of the {@link #execute(org.multiverse.api.Transaction)} method.
|
|
* @throws InvisibleCheckedException if a checked exception was thrown while executing the
|
|
* {@link #execute(org.multiverse.api.Transaction)} method.
|
|
*/
|
|
public final E execute() {
|
|
try {
|
|
return executeChecked();
|
|
} catch (Exception ex) {
|
|
if (ex instanceof RuntimeException) {
|
|
throw (RuntimeException) ex;
|
|
} else {
|
|
throw new AtomicTemplate.InvisibleCheckedException(ex);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Executes the Template and rethrows the checked exception instead of wrapping it
|
|
* in a InvisibleCheckedException.
|
|
*
|
|
* @return the result
|
|
* @throws Exception the Exception thrown inside the {@link #execute(org.multiverse.api.Transaction)}
|
|
* method.
|
|
*/
|
|
public final E executeChecked() throws Exception {
|
|
preStart();
|
|
Transaction t = getTransaction();
|
|
if (t == null || t.getStatus() != TransactionStatus.active) {
|
|
t = readonly ? stm.startReadOnlyTransaction(familyName) : stm.startUpdateTransaction(familyName);
|
|
setTransaction(t);
|
|
postStart(t);
|
|
try {
|
|
attemptCount = 1;
|
|
while (attemptCount - 1 <= retryCount) {
|
|
boolean abort = true;
|
|
boolean reset = false;
|
|
try {
|
|
E result = execute(t);
|
|
preCommit();
|
|
t.commit();
|
|
abort = false;
|
|
reset = false;
|
|
postCommit();
|
|
return result;
|
|
} catch (RetryError e) {
|
|
t.abortAndWaitForRetry();
|
|
//since the abort is already done, no need to do it again.
|
|
abort = false;
|
|
} catch (CommitFailureException ex) {
|
|
reset = true;
|
|
//ignore, just retry the transaction
|
|
} catch (LoadException ex) {
|
|
reset = true;
|
|
//ignore, just retry the transaction
|
|
} finally {
|
|
if (abort) {
|
|
t.abort();
|
|
if (reset) {
|
|
t.reset();
|
|
}
|
|
}
|
|
}
|
|
attemptCount++;
|
|
}
|
|
|
|
throw new TooManyRetriesException();
|
|
} finally {
|
|
setTransaction(null);
|
|
}
|
|
} else {
|
|
return execute(t);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Gets the current Transaction stored in the TransactionThreadLocal.
|
|
* <p/>
|
|
* If the ignoreThreadLocalTransaction is set, the threadlocal stuff
|
|
* is completeley ignored.
|
|
*
|
|
* @return the found transaction, or null if none is found.
|
|
*/
|
|
private Transaction getTransaction() {
|
|
return ignoreThreadLocalTransaction ? null : getThreadLocalTransaction();
|
|
}
|
|
|
|
/**
|
|
* Stores the transaction in the TransactionThreadLocal.
|
|
* <p/>
|
|
* This call is ignored if the ignoreThreadLocalTransaction is true.
|
|
*
|
|
* @param t the transaction to set (is allowed to be null).
|
|
*/
|
|
private void setTransaction(Transaction t) {
|
|
if (!ignoreThreadLocalTransaction) {
|
|
setThreadLocalTransaction(t);
|
|
}
|
|
}
|
|
|
|
public static class InvisibleCheckedException extends RuntimeException {
|
|
public InvisibleCheckedException(Exception cause) {
|
|
super(cause);
|
|
}
|
|
|
|
@Override
|
|
public Exception getCause() {
|
|
return (Exception) super.getCause();
|
|
}
|
|
}
|
|
}
|