Hi,
When you invoke a child command you can specify a specific command context
for the child command to be executed with:
[1]
https://github.com/oVirt/ovirt-engine/blob/31fbb4cb48c7208e6b37c5c0e27560...
If you wish the child command to be executed detached from the parent
command context, you should use the following method [2] for creating the
context for the child command and pass it as the argument for [1]
[2]
https://github.com/oVirt/ovirt-engine/blob/31fbb4cb48c7208e6b37c5c0e27560...
It is up to the developer to decide if the child command should share the
same context as the parent command or use its own detached context.
On Thu, Aug 16, 2018 at 7:21 PM, Andrej Krejcir <akrejcir(a)redhat.com> wrote:
Hi,
I'm changing UpdateClusterCommand to be non-transactive,
and it would use CompensationContext for reverting DB operations.
Reading through CommandBase code, I noticed the following flow seems to be
broken:
1. A command without transaction is executed.
2. It executes a child command, with the compensation context of the
current command. So that the result of the child command can be reverted if
the parent fails.
3. Once the child command successfully finishes, it removes all entity
snapshots from the DB (it calls CommandContext::
cleanupCompensationDataAfterSuccessfulCommand), even if the snapshots
were made by the parent command. See code at [1] and [2].
4. The parent command then fails for some other reason, but its
compensation context is empty, so the DB operations are not reverted
correctly.
Am I missing something or is this flow broken?
Thanks,
Andrej
[1] -
https://github.com/oVirt/ovirt-engine/blob/
31fbb4cb48c7208e6b37c5c0e27560599e15cef9/backend/manager/
modules/bll/src/main/java/org/ovirt/engine/core/bll/CommandBase.java#L1171
[2] -
https://github.com/oVirt/ovirt-engine/blob/
31fbb4cb48c7208e6b37c5c0e27560599e15cef9/backend/manager/
modules/bll/src/main/java/org/ovirt/engine/core/bll/context/
DefaultCompensationContext.java#L206
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Regards,
Moti