package org.opendaylight.mdsal.dom.api;
import com.google.common.util.concurrent.FluentFuture;
-import javax.annotation.CheckReturnValue;
+import edu.umd.cs.findbugs.annotations.CheckReturnValue;
import org.eclipse.jdt.annotation.NonNull;
-import org.opendaylight.mdsal.common.api.AsyncWriteTransaction;
import org.opendaylight.mdsal.common.api.CommitInfo;
-import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
-import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
-import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.mdsal.common.api.DataValidationFailedException;
+import org.opendaylight.mdsal.common.api.OptimisticLockFailedException;
+import org.opendaylight.mdsal.common.api.TransactionCommitFailedException;
/**
- * A transaction that provides mutation capabilities on a data tree.
+ * Write transaction provides mutation capabilities for a data tree.
*
* <p>
- * 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.
+ *
+ * <p>
+ * 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.
+ *
+ * <p>
+ * Applications make changes to the local data tree in the transaction by via the
+ * <b>put</b>, <b>merge</b>, and <b>delete</b> operations.
+ *
+ * <h2>Put operation</h2>
+ * Stores a piece of data at a specified path. This acts as an add / replace
+ * operation, which is to say that whole subtree will be replaced by the
+ * specified data.
+ *
+ * <p>
+ * Performing the following put operations:
+ *
+ * <pre>
+ * 1) container { list [ a ] }
+ * 2) container { list [ b ] }
+ * </pre>
+ * will result in the following data being present:
+ *
+ * <pre>
+ * container { list [ b ] }
+ * </pre>
+ * <h2>Merge operation</h2>
+ * 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.
+ *
+ * <p>
+ * Performing the following merge operations:
+ *
+ * <pre>
+ * 1) container { list [ a ] }
+ * 2) container { list [ b ] }
+ * </pre>
+ * will result in the following data being present:
+ *
+ * <pre>
+ * container { list [ a, b ] }
+ * </pre>
+ * This also means that storing the container will preserve any
+ * augmentations which have been attached to it.
+ *
+ * <h2>Delete operation</h2>
+ * Removes a piece of data from a specified path.
+ *
+ * <p>
+ * 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.
+ *
+ * <p>
+ * 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.
+ *
+ * <p>
+ * <b>Implementation Note:</b> 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<YangInstanceIdentifier, NormalizedNode<?, ?>> {
+public interface DOMDataTreeWriteTransaction extends DOMDataTreeTransaction, DOMDataTreeWriteOperations {
/**
- * Stores a piece of data at the specified path. This acts as an add / replace
- * operation, which is to say that whole subtree will be replaced by the specified data.
+ * Commits this transaction to be asynchronously applied to update the logical data tree. The returned
+ * {@link FluentFuture} conveys the result of applying the data changes.
*
* <p>
- * 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 <code>put(LogicalDatastoreType, Path, Object)</code>,
+ * <code>merge(LogicalDatastoreType, Path, Object)</code>, <code>delete(LogicalDatastoreType, Path)</code> will fail
+ * with {@link IllegalStateException}. The transaction is marked as committed and enqueued into the data store
+ * back-end for processing.
*
* <p>
- * 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.
+ *
+ * <p>
+ * The effects of a successful commit of data depends on listeners and commit participants that are registered with
+ * the data broker.
+ *
+ * <h4>Example usage:</h4>
+ * <pre>
+ * 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);
+ * </pre>
+ *
+ * <h4>Failure scenarios</h4>
*
* <p>
- * For more information on usage and examples, please see the documentation in {@link AsyncWriteTransaction}.
- *
- *<p>
- * 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
+ * <ul>
+ * <li>
+ * Another transaction finished earlier and modified the same node in a non-compatible way (see below). In this
+ * case the returned future will fail with an {@link OptimisticLockFailedException}. It is the responsibility
+ * of the caller to create a new transaction and commit the same modification again in order to update data
+ * tree.
+ * <i>
+ * <b>Warning</b>: In most cases, retrying after an OptimisticLockFailedException will result in a high
+ * probability of success. However, there are scenarios, albeit unusual, where any number of retries will
+ * not succeed. Therefore it is strongly recommended to limit the number of retries (2 or 3) to avoid
+ * an endless loop.
+ * </i>
+ * </li>
+ * <li>Data change introduced by this transaction did not pass validation by commit handlers or data was
+ * incorrectly structured. Returned future will fail with a {@link DataValidationFailedException}. User
+ * should not retry to create new transaction with same data, since it probably will fail again.
+ * </li>
+ * </ul>
+ *
+ * <h4>Change compatibility</h4>
+ * 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.
+ *
+ * <h4>Change compatibility of leafs, leaf-list items</h4>
+ * 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.
+ *
+ * <table>
+ * <caption>Change compatibility of leaf values</caption>
+ * <tr>
+ * <th>Initial state</th>
+ * <th>Tx 1</th>
+ * <th>Tx 2</th>
+ * <th>Result</th>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(A,1)</td>
+ * <td>put(A,2)</td>
+ * <td>Tx 2 will fail, state is A=1</td>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(A,1)</td>
+ * <td>merge(A,2)</td>
+ * <td>A=2</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>Empty</td>
+ * <td>merge(A,1)</td>
+ * <td>put(A,2)</td>
+ * <td>Tx 2 will fail, state is A=1</td>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>merge(A,1)</td>
+ * <td>merge(A,2)</td>
+ * <td>A=2</td>
+ * </tr>
+ *
+ *
+ * <tr>
+ * <td>A=0</td>
+ * <td>put(A,1)</td>
+ * <td>put(A,2)</td>
+ * <td>Tx 2 will fail, A=1</td>
+ * </tr>
+ * <tr>
+ * <td>A=0</td>
+ * <td>put(A,1)</td>
+ * <td>merge(A,2)</td>
+ * <td>A=2</td>
+ * </tr>
+ * <tr>
+ * <td>A=0</td>
+ * <td>merge(A,1)</td>
+ * <td>put(A,2)</td>
+ * <td>Tx 2 will fail, A=1</td>
+ * </tr>
+ * <tr>
+ * <td>A=0</td>
+ * <td>merge(A,1)</td>
+ * <td>merge(A,2)</td>
+ * <td>A=2</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>A=0</td>
+ * <td>delete(A)</td>
+ * <td>put(A,2)</td>
+ * <td>Tx 2 will fail, A does not exists</td>
+ * </tr>
+ * <tr>
+ * <td>A=0</td>
+ * <td>delete(A)</td>
+ * <td>merge(A,2)</td>
+ * <td>A=2</td>
+ * </tr>
+ * </table>
+ *
+ * <h4>Change compatibility of subtrees</h4>
+ * 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.
+ *
+ * <table>
+ * <caption>Change compatibility of containers</caption>
+ * <tr>
+ * <th>Initial state</th>
+ * <th>Tx 1</th>
+ * <th>Tx 2</th>
+ * <th>Result</th>
+ * </tr>
+ *
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(TOP,[])</td>
+ * <td>put(TOP,[])</td>
+ * <td>Tx 2 will fail, state is TOP=[]</td>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(TOP,[])</td>
+ * <td>merge(TOP,[])</td>
+ * <td>TOP=[]</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(TOP,[FOO=1])</td>
+ * <td>put(TOP,[BAR=1])</td>
+ * <td>Tx 2 will fail, state is TOP=[FOO=1]</td>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>put(TOP,[FOO=1])</td>
+ * <td>merge(TOP,[BAR=1])</td>
+ * <td>TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>Empty</td>
+ * <td>merge(TOP,[FOO=1])</td>
+ * <td>put(TOP,[BAR=1])</td>
+ * <td>Tx 2 will fail, state is TOP=[FOO=1]</td>
+ * </tr>
+ * <tr>
+ * <td>Empty</td>
+ * <td>merge(TOP,[FOO=1])</td>
+ * <td>merge(TOP,[BAR=1])</td>
+ * <td>TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>put(TOP,[FOO=1])</td>
+ * <td>put(TOP,[BAR=1])</td>
+ * <td>Tx 2 will fail, state is TOP=[FOO=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>put(TOP,[FOO=1])</td>
+ * <td>merge(TOP,[BAR=1])</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>merge(TOP,[FOO=1])</td>
+ * <td>put(TOP,[BAR=1])</td>
+ * <td>Tx 2 will fail, state is TOP=[FOO=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>merge(TOP,[FOO=1])</td>
+ * <td>merge(TOP,[BAR=1])</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>delete(TOP)</td>
+ * <td>put(TOP,[BAR=1])</td>
+ * <td>Tx 2 will fail, state is empty store</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>delete(TOP)</td>
+ * <td>merge(TOP,[BAR=1])</td>
+ * <td>state is TOP=[BAR=1]</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>put(TOP/FOO,1)</td>
+ * <td>put(TOP/BAR,1])</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>put(TOP/FOO,1)</td>
+ * <td>merge(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>merge(TOP/FOO,1)</td>
+ * <td>put(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>merge(TOP/FOO,1)</td>
+ * <td>merge(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=1,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>delete(TOP)</td>
+ * <td>put(TOP/BAR,1)</td>
+ * <td>Tx 2 will fail, state is empty store</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[]</td>
+ * <td>delete(TOP)</td>
+ * <td>merge(TOP/BAR,1]</td>
+ * <td>Tx 2 will fail, state is empty store</td>
+ * </tr>
+ *
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>put(TOP/FOO,2)</td>
+ * <td>put(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=2,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>put(TOP/FOO,2)</td>
+ * <td>merge(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=2,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>merge(TOP/FOO,2)</td>
+ * <td>put(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=2,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>merge(TOP/FOO,2)</td>
+ * <td>merge(TOP/BAR,1)</td>
+ * <td>state is TOP=[FOO=2,BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>delete(TOP/FOO)</td>
+ * <td>put(TOP/BAR,1)</td>
+ * <td>state is TOP=[BAR=1]</td>
+ * </tr>
+ * <tr>
+ * <td>TOP=[FOO=1]</td>
+ * <td>delete(TOP/FOO)</td>
+ * <td>merge(TOP/BAR,1]</td>
+ * <td>state is TOP=[BAR=1]</td>
+ * </tr>
+ * </table>
+ *
+ *
+ * <h4>Examples of failure scenarios</h4>
+ *
+ * <h5>Conflict of two transactions</h5>
+ * This example illustrates two concurrent transactions, which derived from same initial state
+ * of data tree and proposes conflicting modifications.
+ *
+ * <pre>
+ * 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
+ * </pre>
+ * Commit of transaction A will be processed asynchronously and data tree will be updated to
+ * contain value <code>A</code> for <code>PATH</code>. 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. <br>
+ *
+ * <p>
+ * 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<? extends @NonNull CommitInfo> 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();
}
Code Review / mdsal.git / blobdiff