Package org.alfresco.repo.transaction

Class RetryingTransactionHelper

  • @AlfrescoPublicApi
public class RetryingTransactionHelper
extends java.lang.Object
    A helper that runs a unit of work inside a UserTransaction, transparently retrying the unit of work if the cause of failure is an optimistic locking or deadlock condition.

    Defaults:

    • maxRetries: 20
    • minRetryWaitMs: 100
    • maxRetryWaitMs: 2000
    • retryWaitIncrementMs: 100

    To get details of 'why' transactions are retried use the following log level:
    Summary: log4j.logger.org.alfresco.repo.transaction.RetryingTransactionHelper=INFO
    Details: log4j.logger.org.alfresco.repo.transaction.RetryingTransactionHelper=DEBUG

    Author:
    Derek Hulley

    • Field Detail

      • RETRY_EXCEPTIONS

        public static final java.lang.Class[] RETRY_EXCEPTIONS
        Exceptions that trigger retries.

    • Constructor Detail

      • RetryingTransactionHelper

        public RetryingTransactionHelper()
        Default constructor.

    • Method Detail

      • setTransactionService

        public void setTransactionService​(TransactionService service)
        Set the TransactionService.

      • setMaxRetries

        public void setMaxRetries​(int maxRetries)
        Set the maximimum number of retries. -1 for infinity.

      • setMinRetryWaitMs

        public void setMinRetryWaitMs​(int minRetryWaitMs)

      • setMaxRetryWaitMs

        public void setMaxRetryWaitMs​(int maxRetryWaitMs)

      • setRetryWaitIncrementMs

        public void setRetryWaitIncrementMs​(int retryWaitIncrementMs)

      • setMaxExecutionMs

        public void setMaxExecutionMs​(long maxExecutionMs)

      • setReadOnly

        public void setReadOnly​(boolean readOnly)
        Set whether this helper only supports read transactions.

      • setForceWritable

        public void setForceWritable​(boolean forceWritable)
        Override to allow the transactions to be writable regardless of the system read-only mode.

        NOTE: This method may not be used to circumvent the Alfresco License policy.

        Parameters:
        forceWritable - true to force transactions to be writable regardless of system read-only mode

      • setExtraExceptions

        public void setExtraExceptions​(java.util.List<java.lang.Class<?>> extraExceptions)
        Set the list of extra exceptions that should be retried

      • doInTransaction

        public <R> R doInTransaction​(RetryingTransactionHelper.RetryingTransactionCallback<R> cb)
        Execute a callback in a transaction until it succeeds, fails because of an error not the result of an optimistic locking failure, or a deadlock loser failure, or until a maximum number of retries have been attempted.

        If there is already an active transaction, then the callback is merely executed and any retry logic is left to the caller. The transaction will attempt to be read-write.

        Parameters:
        cb - The callback containing the unit of work.
        Returns:
        Returns the result of the unit of work.
        Throws:
        java.lang.RuntimeException - all checked exceptions are converted

      • doInTransaction

        public <R> R doInTransaction​(RetryingTransactionHelper.RetryingTransactionCallback<R> cb,
                             boolean readOnly)
        Execute a callback in a transaction until it succeeds, fails because of an error not the result of an optimistic locking failure, or a deadlock loser failure, or until a maximum number of retries have been attempted.

        If there is already an active transaction, then the callback is merely executed and any retry logic is left to the caller.

        Parameters:
        cb - The callback containing the unit of work.
        readOnly - Whether this is a read only transaction.
        Returns:
        Returns the result of the unit of work.
        Throws:
        java.lang.RuntimeException - all checked exceptions are converted

      • doInTransaction

        public <R> R doInTransaction​(RetryingTransactionHelper.RetryingTransactionCallback<R> cb,
                             boolean readOnly,
                             boolean requiresNew)
        Execute a callback in a transaction until it succeeds, fails because of an error not the result of an optimistic locking failure, or a deadlock loser failure, or until a maximum number of retries have been attempted.

        It is possible to force a new transaction to be created or to partake in any existing transaction.

        Parameters:
        cb - The callback containing the unit of work.
        readOnly - Whether this is a read only transaction.
        requiresNew - true to force a new transaction or false to partake in any existing transaction.
        Returns:
        Returns the result of the unit of work.
        Throws:
        java.lang.RuntimeException - all checked exceptions are converted

      • extractRetryCause

        public static java.lang.Throwable extractRetryCause​(java.lang.Throwable cause)
        Sometimes, the exception means retry and sometimes not. The stack of exceptions is also checked for any occurence of DoNotRetryException and, if found, nothing is returned.
        Parameters:
        cause - the cause to examine
        Returns:
        Returns the original cause if it is a valid retry cause, otherwise null

      • getActiveUserTransaction

        public static javax.transaction.UserTransaction getActiveUserTransaction()
        Utility method to get the active transaction. The transaction status can be queried and marked for rollback.

        NOTE: Any attempt to actually commit or rollback the transaction will cause failures.

        Returns:
        Returns the currently active user transaction or null if there isn't one.