import ballerina/io;
public function main() returns error? {
transaction {
check update();
check commit;
}
return;
}
transactional function update() returns error? {
check updateDatabase();
// Registers a commit handler to be invoked when the `commit` is executed.
'transaction:onCommit(sendEmail);
'transaction:onRollback(logError);
return;
}
function updateDatabase() returns error? {
io:println("Database updated");
return;
}
isolated function sendEmail('transaction:Info info) {
io:println("Email sent.");
}
isolated function logError('transaction:Info info,
error? cause, boolean willRetry) {
io:println("Logged database update failure");
}
Commit/Rollback HandlersOften code needs to get executed depending on whether a transaction committed. Testing the result of the commit within the transaction statement works, but inconvenient from a modularity perspective, particularly when you want to undo changes on rollback. This seems much worse in a distributed transaction, when transaction statement is in another program. Ballerina provides commit/rollback handlers which are functions that get run when decision whether to commit is known. |
import ballerina/io;
public function main() returns error? {
transaction {
check update();
check commit;
}
return;
}
transactional function update() returns error? {
check updateDatabase();
'transaction:onCommit(sendEmail);
'transaction:onRollback(logError);
return;
}
Registers a commit handler to be invoked when the commit is executed.
function updateDatabase() returns error? {
io:println("Database updated");
return;
}
isolated function sendEmail('transaction:Info info) {
io:println("Email sent.");
}
isolated function logError('transaction:Info info,
error? cause, boolean willRetry) {
io:println("Logged database update failure");
}
bal run commit_rollback_handlers.bal
Database updated
Email sent.
