com.apple.foundationdb

Interface ReadTransactionContext

All Known Subinterfaces:

Database, ReadTransaction, Transaction, TransactionContext

public interface ReadTransactionContext

A context in which a ReadTransaction is available for database operations. The behavior of the methods specified in this interface, especially in the face errors, is implementation specific. In particular, some implementations will run Functions multiple times (retry) when certain errors are encountered. Therefore a Function should be prepared to be called more than once. This consideration means that a Function should use caution when directly modifying state in a class, especially in a way that could be observed were that Function to not complete successfully.

Method Summary

Modifier and Type	Method and Description
java.util.concurrent.Executor	getExecutor() Retrieves the Executor used by this TransactionContext when running asynchronous callbacks.
<T> T	read(java.util.function.Function<? super ReadTransaction,T> retryable) Runs a function in this context that takes a read-only transaction.
<T> java.util.concurrent.CompletableFuture<T>	readAsync(java.util.function.Function<? super ReadTransaction,? extends java.util.concurrent.CompletableFuture<T>> retryable) Runs a function in this context that takes a read-only transaction.

Method Detail

read

<T> T read(java.util.function.Function<? super ReadTransaction,T> retryable)

Runs a function in this context that takes a read-only transaction. Depending on the type of context, this may execute the supplied function multiple times if an error is encountered. This method is blocking -- control will not return from this call until work is complete.

Type Parameters:

T - the return type of retryable

Parameters:

retryable - the block of logic to execute against a ReadTransaction in this context

Returns:

a result of the last call to retryable

readAsync

<T> java.util.concurrent.CompletableFuture<T> readAsync(java.util.function.Function<? super ReadTransaction,? extends java.util.concurrent.CompletableFuture<T>> retryable)

Runs a function in this context that takes a read-only transaction. Depending on the type of context, this may execute the supplied function multiple times if an error is encountered. This call is non-blocking -- control flow will return immediately with a CompletableFuture that will be set when the process is complete.

Type Parameters:

T - the return type of retryable

Parameters:

retryable - the block of logic to execute against a ReadTransaction in this context

Returns:

a CompletableFuture that will be set to the value returned by the last call to retryable

getExecutor

java.util.concurrent.Executor getExecutor()

Retrieves the Executor used by this TransactionContext when running asynchronous callbacks.

Returns:

the Executor used by this TransactionContext