Transactions

pro.aduki.store.queries.Batch runs several writes in one ObjectBox transaction: they commit together or not at all.

class Batch(private val store: BoxStore) {
    fun <T> tx(block: () -> T): T
    fun run(block: () -> Unit)
}

val batch = Batch(boxStore)

val count = batch.tx {
    messageBox.put(newMessages)
    mailbox.modseq = highestModseq
    mailboxBox.put(mailbox)
    outboxBox.remove(actionId)
    newMessages.size
}

If the block throws, every write inside it is rolled back.

The sync engines and the outbox use transactions the same way: applying a page of mailbox changes (messages and the mailbox’s modseq) is one transaction, and an outbox action is journaled in the same transaction as the local change it describes.

ObjectBox serializes write transactions and lets readers run concurrently with a writer; see the ObjectBox documentation for its transaction semantics.