* CORDA-3291 `isKilled` flag and session errors for killed flows
## Summary
Two major improvements have been worked on:
- A new flag named `isKilled` has been added to `FlowLogic` to allow
developers to break out of loops without suspension points.
- Killed flows now send session errors to their counter parties allowing
their flows to also terminate without further coordination.
Achieving these changes required a __fundamental__ change to how flows are
killed as well as how they sleep.
## `isKilled` flag
The addition of `FlowLogic.isKilled` allows flows to check if the
current flow has been killed. They can then throw an exception to lead
to the flow's termination (following the standard error pathway). They
can also perform some extra logic or not throw an exception if they
really wanted to.
No matter what, once the flag is set, the flow will terminate. Due to
timing, a killed flow might successfully process its next suspension
event, but it will then process a killed transition and terminate.
## Send session errors when killing a flow
A flow will now send session errors to all of its counter parties. They
are transferred as `UnexpectedFlowEndException`s. This allows initiated
flows to handle these errors as they see fit, although they should
probably just terminate.
## How flows are killed
### Before
Originally we were relying on Quasar to interrupt a flow's fiber, we
could then handle the resulting `InterruptedException`. The problem with
this solution is that it only worked when a flow was already suspended
or when a flow moved into suspension. Flows stuck in loops did not work.
### After
We now *do not* use Quasar to interrupt a flow's fiber. Instead, we
switch `FlowStateMachine.isKilled` to true and schedule a new event.
Any event that is processed after switching this flag will now cause a
`KilledFlowTransition`. This transition follows similar logic to how
error propagation works. Note, the extra event allows a suspended flow
to be killed without waiting for the event that it was _really_ waiting
for.
This allows a lot of the tidy up code in `StateMachineManager.killFlow`
to be removed as tidy up is executed as part of removing a flow.
Deleting a flow's checkpoint and releasing related soft locks is still
handled manually in case of infinite loops but also triggered as part
of the actions executed in a transition.
This required flow sleeping to be changed as we no longer rely on
quasar.
## How flows now sleep
The reliance on Quasar to make a flow sleep has been removed.
Instead, when a flow sleeps we create a `ScheduledFuture` that is
delayed for the requested sleep duration. When the future executes it
schedules a `WakeUpFromSleep` event that wakes up the flow... Duh.
`FlowSleepScheduler` handles the future logic. It also uses the same
scheduled thread pool that timed flows uses.
A future field was added to `StateMachineState`. This removes the
need for concurrency control around flow sleeps as the code path does
not need to touch any concurrent data structures.
To achieve this:
- `StateMachineState.future` added as a `var`
- When the `ScheduledFuture` is created to wake up the flow the passed
in `StateMachineState` has its `future` value changed
- When resumed `future` and `isWaitingForFuture` are set to `null` and
`false` respectively
- When cancelling a sleeping flow, the `future` is cancelled and nulled
out. `isWaitingForFuture` is not changed since the flow is ending anyway
so really the value of the field is not important.
* CORDA-3722 withEntityManager can rollback its session
## Summary
Improve the handling of database transactions when using
`withEntityManager` inside a flow.
Extra changes have been included to improve the safety and
correctness of Corda around handling database transactions.
This focuses on allowing flows to catch errors that occur inside an
entity manager and handle them accordingly.
Errors can be caught in two places:
- Inside `withEntityManager`
- Outside `withEntityManager`
Further changes have been included to ensure that transactions are
rolled back correctly.
## Catching errors inside `withEntityManager`
Errors caught inside `withEntityManager` require the flow to manually
`flush` the current session (the entity manager's individual session).
By manually flushing the session, a `try-catch` block can be placed
around the `flush` call, allowing possible exceptions to be caught.
Once an error is thrown from a call to `flush`, it is no longer possible
to use the same entity manager to trigger any database operations. The
only possible option is to rollback the changes from that session.
The flow can continue executing updates within the same session but they
will never be committed. What happens in this situation should be handled
by the flow. Explicitly restricting the scenario requires a lot of effort
and code. Instead, we should rely on the developer to control complex
workflows.
To continue updating the database after an error like this occurs, a new
`withEntityManager` block should be used (after catching the previous
error).
## Catching errors outside `withEntityManager`
Exceptions can be caught around `withEntityManager` blocks. This allows
errors to be handled in the same way as stated above, except the need to
manually `flush` the session is removed. `withEntityManager` will
automatically `flush` a session if it has not been marked for rollback
due to an earlier error.
A `try-catch` can then be placed around the whole of the
`withEntityManager` block, allowing the error to be caught while not
committing any changes to the underlying database transaction.
## Savepoints / Transactionality
To make `withEntityManager` blocks work like mini database transactions,
save points have been utilised. A new savepoint is created when opening
a `withEntityManager` block (along with a new session). It is then used
as a reference point to rollback to if the session errors and needs to
roll back. The savepoint is then released (independently from
completing successfully or failing).
Using save points means, that either all the statements inside the
entity manager are executed, or none of them are.
## Some implementation details
- A new session is created every time an entity manager is requested,
but this does not replace the flow's main underlying database session.
- `CordaPersistence.transaction` can now determine whether it needs
to execute its extra error handling code. This is needed to allow errors
escape `withEntityManager` blocks while allowing some of our exception
handling around subscribers (in `NodeVaultService`) to continue to work.
On node start, load CordaServices before starting the NotaryService,
so that the NotaryService can check that the services it requires are
available when starting.
Resolves#6172.
* Retired the rst doc source structure under /docs and updated the /docs/README.md
*Rollback of /example-code and /whitepaper dirs back under /docs dir until new code example process is in place
* CORDA-3762: Integration test exposing the problem reported
* CORDA-3726: Additional logging
* CORDA-3726: Prevent thread leaks
* CORDA-3726: New `journalBufferTimeout` parameter
* CORDA-3726: Override `journalBufferTimeout` parameter
* CORDA-3726: Making Detekt happier
* CORDA-3276: Account for extra thread user in MockNetwork
For real node this does not matter as `shutdown` can safely be called multiple times, which is not true for server thread provided by MockNetwork
* CORDA-3276: Do not make SMM shutdown "executor" as it belongs to AbstractNode
* CORDA-3276: Address input from @rick-r3
* CORDA-3276: Fix test after rebase
* CORDA-3701 Fix bugs in some iterator checkpoint serializers
* Added some more tests and tidied up implementation some more.
* Fix imports to be detekt compliant
* Add timeouts to tests
* adding blocked functions ro RestrictedEntityManager and creating RestrictedConnection class
* adding flow tests and fixing issues regarding the review
* adding quasar util to gradle
* updating flow tests
* adding space before } at .isThrownBy()
* adding spaces
* CORDA-3716: Fix SandboxEnumSerializer to handle enums that override toString().
* Remove more uses of Enum.toString() from the Corda serializer.
* Add test coverage for this case to standard enum serializer.
* Increase maxWaitTimeout in IRSDemoTest to 150 seconds.
* CORDA-3716: Fix SandboxEnumSerializer to handle enums that override toString().
* Remove more uses of Enum.toString() from the Corda serializer.
* Add test coverage for this case to standard enum serializer.
* Increase maxWaitTimeout in IRSDemoTest to 150 seconds.
* [EG-503] Spent state audit tool
Fixes
* Refinements to notary query interfaces. Feature complete.
* EG-503: Introduce optional `notaryService` in `ServiceHubCoreInternal`
* Remove redundant logic following change to use extensions API
Co-authored-by: Viktor Kolomeyko <viktor.kolomeyko@r3.com>
* CORDA-3696: Temporary update to enable JDK11 build and test. Will eventually be switchable.
* CORDA-3696: Filter out the Nashorn warning.
* CORDA-3696: Add JDK11 classifier.
* CORDA-3696: Updated match string to cope with JDK11.
* CORDA-3696: Filtering out SPHINCS256_SHA256 where failing due to JDK11.
* CORDA-3696: Now remove SPHINCS256_SHA256 only if JDK11.
* CORDA-3696: Fix test failure - switch to regex matching.
* CORDA-3696: Hide the illegal access warnings.
* CORDA-3696: Check for Java11 when disabling Java11 warnings.
* CORDA-3696: Fix unneccessary non null check.
* CORDA-3696: Reverting build env to JDK8
* CORDA-3696: Revert hiding of illegal access warnings via Unsafe class.
* CORDA-3696: Remove internal access warnings and new JDK11 version checker.
* CORDA-3696: Updated build file for OS
* CORDA-3696: Removed typo
* CORDA-3696: Fixed space typo.
* CORDA-3696: Open modules to remove the illegal access warnings.
Co-authored-by: Adel El-Beik <adelel-beik@19LDN-MAC108.local>
* ENT-4967: Require no classifier for corda-node-djvm, corda-deserializers-djvm.
* Also remove classifiers from core, serialization and finance-contracts.
* Compile corda-serialization-djvm for Java 8 and remove its classifier.
the current code doesn't forward the exception to the logging system, this means that any cause inside the exception is lost as with all of the stacktraces (both the one of the thrown exception and the one belonging to its cause).
The correct way to log an exception is to pass both the message and the exception to the logging system.
* CORDA-3690: Changed algorithm name used in signature from ECDSA to EC. JDK11 checks with in key generation.
* CORDA-3690: Remove the SHA512WITHSPHINCS256 signature scheme from the generate key pair and sign test.
* CORDA-3690: Algorithm in SignatureScheme has changed to EC from ECDSA so change test to match.
Co-authored-by: Adel El-Beik <adelel-beik@19LDN-MAC108.local>
