runBlock

Execute a non-deterministic closure, recording the result value in the journal. The result value will be re-played in case of re-invocation (e.g. because of failure recovery or suspension point) without re-executing the closure. Use this feature if you want to perform non-deterministic operations.

You can name this closure using the name parameter. This name will be available in the observability tools.

The closure should tolerate retries, that is Restate might re-execute the closure multiple times until it records a result. To control and limit the amount of retries, pass a [RetryPolicy] to this function.

Error handling

Errors occurring within this closure won't be propagated to the caller, unless they are TerminalException. Consider the following code:

// Bad usage of try-catch outside the runBlock
try {
    ctx.runBlock {
        throw IllegalStateException();
    };
} catch (e: IllegalStateException) {
    // This will never be executed,
    // but the error will be retried by Restate,
    // following the invocation retry policy.
}

// Good usage of try-catch outside the runBlock
try {
    ctx.runBlock {
        throw TerminalException("my error");
    };
} catch (e: TerminalException) {
    // This is invoked
}

To propagate failures to the run call-site, make sure to wrap them in TerminalException.

Parameters