[Fix #1247] Adding sync/async implementations

[fjtirado]

Fix #1247

[Copilot]

Pull request overview

Introduces a PersistenceExecutor abstraction to support synchronous and asynchronous persistence execution paths, and wires these into persistence instance writing to address #1247.

Changes:

• Added PersistenceExecutor interface plus SyncPersistenceExecutor and async implementations.
• Introduced TransactedPersistenceInstanceWriter to route persistence operations through a PersistenceExecutor.
• Updated default persistence handlers/writer to use the new executor model (sync by default, async when configured).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/TransactedPersistenceInstanceWriter.java	Adds a writer base that executes persistence actions via a PersistenceExecutor.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/SyncPersistenceExecutor.java	Adds a synchronous executor implementation.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/PersistenceExecutor.java	Defines executor contract with lifecycle hooks for start/delete.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/DefaultPersistenceInstanceWriter.java	Switches default writer to the new transacted/executor model.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/DefaultPersistenceInstanceHandlers.java	Wires builder configuration to create sync/async executors.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/AsyncPersistenceInstanceWriter.java	Refactors prior async writer logic into an async executor implementation.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/AsyncPersistenceExecutor.java	Adds a concrete async executor that supplies an ExecutorService.
impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/AbstractPersistenceInstanceWriter.java	Splits “start” and “complete” hooks from generic transaction execution.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/AbstractAsyncPersistenceExecutor.java:61

• deleteInstance can skip the provided delete runnable entirely when there is no pending future for the instance (it returns a completed future without running runnable). This means completed/failed/aborted may not remove the process instance for workflows that don't enqueue any async writes after startInstance (which is currently synchronous), leaving stale state. Also, canceling the in-flight future can interrupt/cancel queued persistence writes and causes the returned future to complete exceptionally (CancellationException), which defeats the goal of ensuring persistence completes before instance deletion. Consider always executing the runnable, and when a prior future exists, chain the runnable to run after that future settles (without canceling it), returning a future that represents the delete runnable's completion.
  impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/AbstractAsyncPersistenceExecutor.java:75
• close() waits on each future via future.get(), but it doesn't handle CancellationException. With the current deleteInstance implementation canceling futures, close() can throw at runtime and skip draining/clearing remaining entries. Either avoid canceling the futures in deleteInstance, or handle CancellationException here similarly to ExecutionException to keep shutdown robust.

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