com.google.cloud.spanner

Interface TransactionRunner.TransactionCallable<T>

Enclosing interface:

TransactionRunner

public static interface TransactionRunner.TransactionCallable<T>

A unit of work to be performed in the context of a transaction.

Method Summary

Modifier and Type	Method and Description
T	run(TransactionContext transaction) Invoked by the library framework to perform a single attempt of a transaction.

Method Detail

run

@Nullable
T run(TransactionContext transaction)
         throws Exception

Invoked by the library framework to perform a single attempt of a transaction. This method may be called more than once if previous transaction attempts aborted. Each invocation can perform zero or more reads or queries and can buffer mutations to be applied to the database when the transaction commits.

The framework will attempt to commit the transaction when this method returns normally. If commit is successful, the return value from this method will be returned from TransactionRunner.run(TransactionCallable); on failure, the transaction may be retried by the framework by calling the method again.

If this method raises an exception, one of two things can happen. If some operation in the transaction has previously detected that the transaction has been aborted, the framework may retry the transaction. Otherwise, the framework will roll back the transaction, releasing any locks held, and yield the exception to the caller as a SpannerException of type ErrorCode.UNKNOWN with the exception as the cause.

Throws:

Exception