- * For more information on usage and examples, please see the documentation in {@link AsyncWriteTransaction}. + * Initial state of write transaction is a stable snapshot of the current data tree. + * The state is captured when the transaction is created and its state and underlying + * data tree are not affected by other concurrently running transactions. + * + *
+ * Write transactions are isolated from other concurrent write transactions. All + * writes are local to the transaction and represent only a proposal of state + * change for the data tree and it is not visible to any other concurrently running + * transaction. + * + *
+ * Applications make changes to the local data tree in the transaction by via the + * put, merge, and delete operations. + * + *
+ * Performing the following put operations: + * + *
+ * 1) container { list [ a ] }
+ * 2) container { list [ b ] }
+ *
+ * will result in the following data being present:
+ *
+ *
+ * container { list [ b ] }
+ *
+ * + * Performing the following merge operations: + * + *
+ * 1) container { list [ a ] }
+ * 2) container { list [ b ] }
+ *
+ * will result in the following data being present:
+ *
+ *
+ * container { list [ a, b ] }
+ *
+ * This also means that storing the container will preserve any
+ * augmentations which have been attached to it.
+ *
+ * + * After applying changes to the local data tree, applications publish the changes proposed in the + * transaction by calling {@link #commit} on the transaction. This seals the transaction + * (preventing any further writes using this transaction) and commits it to be + * processed and applied to global conceptual data tree. + * + *
+ * The transaction commit may fail due to a concurrent transaction modifying and committing data in + * an incompatible way. See {@link #commit} for more concrete commit failure examples. + * + *
+ * Implementation Note: This interface is not intended to be implemented
+ * by users of MD-SAL, but only to be consumed by them.
*/
-public interface DOMDataTreeWriteTransaction extends DOMDataTreeTransaction,
- AsyncWriteTransaction
- * For more information on usage and examples, please see the documentation in {@link AsyncWriteTransaction}.
+ * This call logically seals the transaction, which prevents the client from further changing the data tree using
+ * this transaction. Any subsequent calls to
- * If you need to make sure that a parent object exists but you do not want modify
- * its pre-existing state by using put, consider using {@link #merge} instead.
- *
- * @param store
- * the logical data store which should be modified
- * @param path
- * the data object path
- * @param data
- * the data object to be written to the specified path
- * @throws IllegalStateException
- * if the transaction has already been submitted
- */
- void put(LogicalDatastoreType store, YangInstanceIdentifier path, NormalizedNode data);
-
- /**
- * Merges a piece of data with the existing data at a specified path. Any pre-existing data
- * which is not explicitly overwritten will be preserved. This means that if you store a container,
- * its child lists will be merged.
+ * Whether or not the commit is successful is determined by versioning of the data tree and validation of registered
+ * commit participants if the transaction changes the data tree.
+ *
+ *
+ * The effects of a successful commit of data depends on listeners and commit participants that are registered with
+ * the data broker.
+ *
+ *
- * For more information on usage and examples, please see the documentation in {@link AsyncWriteTransaction}.
- *
- *
- * If you require an explicit replace operation, use {@link #put} instead.
- *
- * @param store
- * the logical data store which should be modified
- * @param path
- * the data object path
- * @param data
- * the data object to be merged to the specified path
- * @throws IllegalStateException
- * if the transaction has already been submitted
+ * Transaction may fail because of multiple reasons, such as
+ *
+ * A successful commit produces implementation-specific {@link CommitInfo} structure, which is used to communicate
+ * post-condition information to the caller. Such information can contain commit-id, timing information or any
+ * other information the implementation wishes to share.
+ *
+ * @return a FluentFuture containing the result of the commit information. The Future blocks until the commit
+ * operation is complete. A successful commit returns nothing. On failure, the Future will fail with a
+ * {@link TransactionCommitFailedException} or an exception derived from TransactionCommitFailedException.
+ * @throws IllegalStateException if the transaction is already committed or was canceled.
*/
- void merge(LogicalDatastoreType store, YangInstanceIdentifier path, NormalizedNode data);
-
- @Override
- void delete(LogicalDatastoreType store, YangInstanceIdentifier path);
-
- @Override
@CheckReturnValue
@NonNull FluentFuture commit();
- @Override
+ /**
+ * Cancels the transaction. Transactions can only be cancelled if it was not yet committed.
+ * Invoking cancel() on failed or already canceled will have no effect, and transaction is considered cancelled.
+ * Invoking cancel() on finished transaction (future returned by {@link #commit()} already successfully completed)
+ * will always fail (return false).
+ *
+ * @return {@code false} if the task could not be cancelled, typically because it has already completed normally;
+ * {@code true} otherwise
+ */
boolean cancel();
}
put(LogicalDatastoreType, Path, Object),
+ * merge(LogicalDatastoreType, Path, Object), delete(LogicalDatastoreType, Path) will fail
+ * with {@link IllegalStateException}. The transaction is marked as committed and enqueued into the data store
+ * back-end for processing.
*
* Example usage:
+ *
+ * private void doWrite(final int tries) {
+ * WriteTransaction writeTx = dataBroker.newWriteOnlyTransaction();
+ * MyDataObject data = ...;
+ * InstanceIdentifier<MyDataObject> path = ...;
+ * writeTx.put(LogicalDatastoreType.OPERATIONAL, path, data);
+ * Futures.addCallback(writeTx.commit(), new FutureCallback<CommitInfo>() {
+ * public void onSuccess(CommitInfo result) {
+ * // succeeded
+ * }
+ * public void onFailure(Throwable t) {
+ * if (t instanceof OptimisticLockFailedException) {
+ * if(( tries - 1) > 0 ) {
+ * // do retry
+ * doWrite(tries - 1);
+ * } else {
+ * // out of retries
+ * }
+ * } else {
+ * // failed due to another type of TransactionCommitFailedException.
+ * }
+ * });
+ * }
+ * ...
+ * doWrite(2);
+ *
+ *
+ * Failure scenarios
*
*
+ *
+ *
+ * Change compatibility
+ * There are several sets of changes which could be considered incompatible between two transactions which are
+ * derived from same initial state. Rules for conflict detection applies recursively for each subtree level.
+ *
+ * Change compatibility of leafs, leaf-list items
+ * Following table shows state changes and failures between two concurrent transactions, which are based on same
+ * initial state, Tx 1 completes successfully before Tx 2 is committed.
+ *
+ *
+ *
+ *
+ *
+ *
+ * Initial state
+ * Tx 1
+ * Tx 2
+ * Result
+ *
+ *
+ * Empty
+ * put(A,1)
+ * put(A,2)
+ * Tx 2 will fail, state is A=1
+ *
+ *
+ *
+ * Empty
+ * put(A,1)
+ * merge(A,2)
+ * A=2
+ *
+ *
+ * Empty
+ * merge(A,1)
+ * put(A,2)
+ * Tx 2 will fail, state is A=1
+ *
+ *
+ *
+ *
+ * Empty
+ * merge(A,1)
+ * merge(A,2)
+ * A=2
+ *
+ *
+ * A=0
+ * put(A,1)
+ * put(A,2)
+ * Tx 2 will fail, A=1
+ *
+ *
+ * A=0
+ * put(A,1)
+ * merge(A,2)
+ * A=2
+ *
+ *
+ * A=0
+ * merge(A,1)
+ * put(A,2)
+ * Tx 2 will fail, A=1
+ *
+ *
+ *
+ * A=0
+ * merge(A,1)
+ * merge(A,2)
+ * A=2
+ *
+ *
+ * A=0
+ * delete(A)
+ * put(A,2)
+ * Tx 2 will fail, A does not exists
+ *
+ *
+ * A=0
+ * delete(A)
+ * merge(A,2)
+ * A=2
+ * Change compatibility of subtrees
+ * Following table shows state changes and failures between two concurrent transactions, which are based on same
+ * initial state, Tx 1 completes successfully before Tx 2 is committed.
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ * Initial state
+ * Tx 1
+ * Tx 2
+ * Result
+ *
+ *
+ * Empty
+ * put(TOP,[])
+ * put(TOP,[])
+ * Tx 2 will fail, state is TOP=[]
+ *
+ *
+ *
+ * Empty
+ * put(TOP,[])
+ * merge(TOP,[])
+ * TOP=[]
+ *
+ *
+ * Empty
+ * put(TOP,[FOO=1])
+ * put(TOP,[BAR=1])
+ * Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ *
+ *
+ * Empty
+ * put(TOP,[FOO=1])
+ * merge(TOP,[BAR=1])
+ * TOP=[FOO=1,BAR=1]
+ *
+ *
+ * Empty
+ * merge(TOP,[FOO=1])
+ * put(TOP,[BAR=1])
+ * Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ *
+ *
+ * Empty
+ * merge(TOP,[FOO=1])
+ * merge(TOP,[BAR=1])
+ * TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * put(TOP,[FOO=1])
+ * put(TOP,[BAR=1])
+ * Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ *
+ * TOP=[]
+ * put(TOP,[FOO=1])
+ * merge(TOP,[BAR=1])
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * merge(TOP,[FOO=1])
+ * put(TOP,[BAR=1])
+ * Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ *
+ * TOP=[]
+ * merge(TOP,[FOO=1])
+ * merge(TOP,[BAR=1])
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * delete(TOP)
+ * put(TOP,[BAR=1])
+ * Tx 2 will fail, state is empty store
+ *
+ *
+ *
+ * TOP=[]
+ * delete(TOP)
+ * merge(TOP,[BAR=1])
+ * state is TOP=[BAR=1]
+ *
+ *
+ * TOP=[]
+ * put(TOP/FOO,1)
+ * put(TOP/BAR,1])
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * put(TOP/FOO,1)
+ * merge(TOP/BAR,1)
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * merge(TOP/FOO,1)
+ * put(TOP/BAR,1)
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * merge(TOP/FOO,1)
+ * merge(TOP/BAR,1)
+ * state is TOP=[FOO=1,BAR=1]
+ *
+ *
+ * TOP=[]
+ * delete(TOP)
+ * put(TOP/BAR,1)
+ * Tx 2 will fail, state is empty store
+ *
+ *
+ *
+ * TOP=[]
+ * delete(TOP)
+ * merge(TOP/BAR,1]
+ * Tx 2 will fail, state is empty store
+ *
+ *
+ * TOP=[FOO=1]
+ * put(TOP/FOO,2)
+ * put(TOP/BAR,1)
+ * state is TOP=[FOO=2,BAR=1]
+ *
+ *
+ * TOP=[FOO=1]
+ * put(TOP/FOO,2)
+ * merge(TOP/BAR,1)
+ * state is TOP=[FOO=2,BAR=1]
+ *
+ *
+ * TOP=[FOO=1]
+ * merge(TOP/FOO,2)
+ * put(TOP/BAR,1)
+ * state is TOP=[FOO=2,BAR=1]
+ *
+ *
+ * TOP=[FOO=1]
+ * merge(TOP/FOO,2)
+ * merge(TOP/BAR,1)
+ * state is TOP=[FOO=2,BAR=1]
+ *
+ *
+ * TOP=[FOO=1]
+ * delete(TOP/FOO)
+ * put(TOP/BAR,1)
+ * state is TOP=[BAR=1]
+ *
+ *
+ * TOP=[FOO=1]
+ * delete(TOP/FOO)
+ * merge(TOP/BAR,1]
+ * state is TOP=[BAR=1]
+ * Examples of failure scenarios
+ *
+ * Conflict of two transactions
+ * This example illustrates two concurrent transactions, which derived from same initial state
+ * of data tree and proposes conflicting modifications.
+ *
+ *
+ * txA = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
+ * txB = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
+ * txA.put(CONFIGURATION, PATH, A); // writes to PATH value A
+ * txB.put(CONFIGURATION, PATH, B) // writes to PATH value B
+ * ListenableFuture futureA = txA.commit(); // transaction A is sealed and committed
+ * ListenebleFuture futureB = txB.commit(); // transaction B is sealed and committed
+ *
+ * Commit of transaction A will be processed asynchronously and data tree will be updated to
+ * contain value A for PATH. Returned {@link FluentFuture} will
+ * successfully complete once state is applied to data tree.
+ * Commit of Transaction B will fail, because previous transaction also modified path in a
+ * concurrent way. The state introduced by transaction B will not be applied. Returned
+ * {@link FluentFuture} object will fail with {@link OptimisticLockFailedException}
+ * exception, which indicates to client that concurrent transaction prevented the committed
+ * transaction from being applied.
+ *
+ *