René Cordier created JAMES-3057:
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Summary: Implement a MailboxMapper::create method
Key: JAMES-3057
URL: https://issues.apache.org/jira/browse/JAMES-3057
Project: James Server
Issue Type: Improvement
Components: mailbox
Reporter: René Cordier
*Why*
Currently, creating and renaming a mailbox trigger the same operation.
Looking at CassandraMapper, we got the following code:
{code:java}
private boolean trySave(Mailbox cassandraMailbox, CassandraId cassandraId) {
boolean isCreated =
mailboxPathV2DAO.save(cassandraMailbox.generateAssociatedPath(),
cassandraId).block();
if (isCreated) {
Optional<Mailbox> simpleMailbox =
retrieveMailbox(cassandraId).blockOptional();
simpleMailbox.ifPresent(mbx ->
mailboxPathV2DAO.delete(mbx.generateAssociatedPath()).block());
mailboxDAO.save(cassandraMailbox).block();
}
return isCreated;
}
{code}
This means that upon create we try to perform a useless read to see if the
mailbox previously existed.
Such read-before-writes is a Cassandra anti-pattern that should be avoided.
If this read fails, then the mailbox table is never updated, and we have an
inconsistency.
*Proposal*
We need to have a new method in the MailboxMapper:
{code:java}
// @throws if exists
Mailbox create(MailboxPath path, UidValidity uidValidity) throws
MailboxException;
{code}
We will provide a default method leveraging existing `save`.
We will implement it in `mailbox/cassandra` in order to skip the read before
writes:
{code:java}
// Some comments here
private boolean tryCreate(MailboxPath path, UidValidity uidValidity) {
// Generate mailbox
boolean isCreated =
mailboxPathV2DAO.save(cassandraMailbox.generateAssociatedPath(),
cassandraId).block();
if (isCreated) {
mailboxDAO.save(cassandraMailbox).block();
}
// TODO Reactor chain this?
return isCreated;
}
{code}
Unit test have to be written for MailboxMapper::create.
StoreMailboxManager::performConcurrentMailboxCreation needs to be adapted, and
StoreMailboxManager::doCreateMailbox removed.
*Kisscool refactoring effect*
Maybe `Mailbox.mailboxId` can be made final once this change done. :-)
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