Operating System: Windows
Platform: PC

https://wiki.opendaylight.org/view/OpenDaylight_Controller:MD-SAL:Migration:Data_Broker#New_API_-_Write.2FCommit.2FRetry_Example

The example isn't quite right. The logic needs to exhibit a read/modify/write loop and (in a synchronous pseudocode to make it easy to follow) it would look roughly like:

while (true) {
try

catch (ConcurrentModificationException)

}

The read/modify part here is important for correctness, since if you get this exception if you just keep retrying your write you'll lose the data that was written by the other process or thread.

Updated to:

private void readWriteRetry() {
ReadWriteTransaction writeTx = dataBroker.newReadWriteTransaction();

Optional<DataObject> readed = writeTx.read(LogicalDatastoreType.OPERATIONAL,PATH).get();
DataObject modified = modifyData(readed);
writeTx.put(LogicalDatastoreType.OPERATIONAL, PATH, data);
ListenableFuture<RpcResult<TransactionStatus>> future = writeTx.commit();

Futures.addCallback(future, new FutureCallback<RpcResult<TransactionStatus>>() {

@Override
public void onSuccess(final RpcResult<TransactionStatus> result)

@Override
public void onFailure(final Throwable t) {
// Transaction failed

if(t instanceof OptimisticLockFailedException)

}
});
}

This example is bit harder to read than your pseudocode, but illustrates read/write/retry using ListenableFutures
to get transaction status.

Looks much better, though this documentation really shouldn't be on this hidden page. I might change to:

private void readWriteRetry(RelevantEvent event)

but this is not critical.

By the way, do we recommend calling get() on the read operation future? Or are you supposed to write the double chain of async events?

Is each module supposed to allocate its own executor or is there a global shared one to use?

Futures.addCallback(Future,FutureCallback) for callback uses thread in which future completed (e.g. MD-SAL thread in this use cases). Futures.addCallback(Future,FutureCallback,Executor) uses executor of your choice.

We do not have global shared executor.