2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.md.sal.common.api.data;
10 import org.opendaylight.controller.md.sal.common.api.TransactionStatus;
11 import org.opendaylight.yangtools.concepts.Path;
12 import org.opendaylight.yangtools.yang.common.RpcResult;
14 import com.google.common.util.concurrent.CheckedFuture;
15 import com.google.common.util.concurrent.ListenableFuture;
18 * Write transaction provides mutation capabilities for a data tree.
21 * Initial state of write transaction is a stable snapshot of the current data tree.
22 * The state is captured when the transaction is created and its state and underlying
23 * data tree are not affected by other concurrently running transactions.
25 * Write transactions are isolated from other concurrent write transactions. All
26 * writes are local to the transaction and represent only a proposal of state
27 * change for the data tree and it is not visible to any other concurrently running
30 * Applications publish the changes proposed in the transaction by calling {@link #commit}
31 * on the transaction. This seals the transaction
32 * (preventing any further writes using this transaction) and submits it to be
33 * processed and applied to global conceptual data tree.
35 * The transaction commit may fail due to a concurrent transaction modifying and committing data in
36 * an incompatible way. See {@link #commit()} for more concrete commit failure examples.
40 * <b>Implementation Note:</b> This interface is not intended to be implemented
41 * by users of MD-SAL, but only to be consumed by them.
44 * Type of path (subtree identifier), which represents location in
47 * Type of data (payload), which represents data payload
49 public interface AsyncWriteTransaction<P extends Path<P>, D> extends AsyncTransaction<P, D> {
51 * Cancels the transaction.
53 * Transactions can only be cancelled if it's status is
54 * {@link TransactionStatus#NEW} or {@link TransactionStatus#SUBMITED}
56 * Invoking cancel() on {@link TransactionStatus#FAILED} or
57 * {@link TransactionStatus#CANCELED} will have no effect, and transaction
58 * is considered cancelled.
60 * Invoking cancel() on finished transaction (future returned by {@link #commit()}
61 * already completed with {@link TransactionStatus#COMMITED}) will always
62 * fail (return false).
64 * @return <tt>false</tt> if the task could not be cancelled,
65 * typically because it has already completed normally;
66 * <tt>true</tt> otherwise
72 * Store a piece of data at specified path. This acts as an add / replace
73 * operation, which is to say that whole subtree will be replaced by
74 * specified path. Performing the following put operations:
77 * 1) container { list [ a ] }
78 * 2) container { list [ b ] }
81 * will result in the following data being present:
84 * container { list [ b ] }
88 * If you need to make sure that a parent object exists, but you do not want modify
89 * its preexisting state by using put, consider using
90 * {@link #merge(LogicalDatastoreType, Path, Object)}
93 * Logical data store which should be modified
97 * Data object to be written to specified path
98 * @throws IllegalStateException
99 * if the transaction is no longer {@link TransactionStatus#NEW}
101 void put(LogicalDatastoreType store, P path, D data);
104 * Store a piece of data at the specified path. This acts as a merge operation,
105 * which is to say that any pre-existing data which is not explicitly
106 * overwritten will be preserved. This means that if you store a container,
107 * its child lists will be merged. Performing the following merge
111 * 1) container { list [ a ] }
112 * 2) container { list [ b ] }
115 * will result in the following data being present:
118 * container { list [ a, b ] }
121 * This also means that storing the container will preserve any
122 * augmentations which have been attached to it.
124 * If you require an explicit replace operation, use
125 * {@link #put(LogicalDatastoreType, Path, Object)} instead.
128 * Logical data store which should be modified
132 * Data object to be written to specified path
133 * @throws IllegalStateException
134 * if the transaction is no longer {@link TransactionStatus#NEW}
136 void merge(LogicalDatastoreType store, P path, D data);
139 * Remove a piece of data from specified path. This operation does not fail
140 * if the specified path does not exist.
143 * Logical data store which should be modified
146 * @throws IllegalStateException
147 * if the transaction is no longer {@link TransactionStatus#NEW}
149 void delete(LogicalDatastoreType store, P path);
152 * Submits this transaction to be asynchronously applied to update the logical data tree.
153 * The returned CheckedFuture conveys the result of applying the data changes.
155 * <b>Note:</b> It is strongly recommended to process the CheckedFuture result in an asynchronous
156 * manner rather than using the blocking get() method. See example usage below.
158 * This call logically seals the transaction, which prevents the client from
159 * further changing data tree using this transaction. Any subsequent calls to
160 * {@link #put(LogicalDatastoreType, Path, Object)},
161 * {@link #merge(LogicalDatastoreType, Path, Object)} or
162 * {@link #delete(LogicalDatastoreType, Path)} will fail with
163 * {@link IllegalStateException}.
165 * The transaction is marked as {@link TransactionStatus#SUBMITED} and
166 * enqueued into the data store back-end for processing.
169 * Whether or not the commit is successful is determined by versioning
170 * of the data tree and validation of registered commit participants
171 * ({@link AsyncConfigurationCommitHandler})
172 * if the transaction changes the data tree.
174 * The effects of a successful commit of data depends on data change listeners
175 * ({@link AsyncDataChangeListener}) and commit participants
176 * ({@link AsyncConfigurationCommitHandler}) that are registered with the data broker.
178 * <h3>Example usage:</h3>
180 * private void doWrite( final int tries ) {
181 * WriteTransaction writeTx = dataBroker.newWriteOnlyTransaction();
183 * MyDataObject data = ...;
184 * InstanceIdentifier<MyDataObject> path = ...;
185 * writeTx.put( LogicalDatastoreType.OPERATIONAL, path, data );
187 * Futures.addCallback( writeTx.commit(), new FutureCallback<Void>() {
188 * public void onSuccess( Void result ) {
192 * public void onFailure( Throwable t ) {
193 * if( t instanceof OptimisticLockFailedException ) {
194 * if( ( tries - 1 ) > 0 ) {
196 * doWrite( tries - 1 );
201 * // failed due to another type of TransactionCommitFailedException.
208 * <h2>Failure scenarios</h2>
210 * Transaction may fail because of multiple reasons, such as
212 * <li>Another transaction finished earlier and modified the same node in a
213 * non-compatible way (see below). In this case the returned future will fail with an
214 * {@link OptimisticLockFailedException}. It is the responsibility of the
215 * caller to create a new transaction and submit the same modification again in
216 * order to update data tree. <i><b>Warning</b>: In most cases, retrying after an
217 * OptimisticLockFailedException will result in a high probability of success.
218 * However, there are scenarios, albeit unusual, where any number of retries will
219 * not succeed. Therefore it is strongly recommended to limit the number of retries (2 or 3)
220 * to avoid an endless loop.</i>
222 * <li>Data change introduced by this transaction did not pass validation by
223 * commit handlers or data was incorrectly structured. Returned future will
224 * fail with a {@link DataValidationFailedException}. User should not retry to
225 * create new transaction with same data, since it probably will fail again.
229 * <h3>Change compatibility</h3>
231 * There are several sets of changes which could be considered incompatible
232 * between two transactions which are derived from same initial state.
233 * Rules for conflict detection applies recursively for each subtree
236 * <h4>Change compatibility of leafs, leaf-list items</h4>
238 * Following table shows state changes and failures between two concurrent transactions,
239 * which are based on same initial state, Tx 1 completes successfully
240 * before Tx 2 is submitted.
243 * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
244 * <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>
245 * <tr><td>Empty</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
247 * <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>
248 * <tr><td>Empty</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
251 * <tr><td>A=0</td><td>put(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
252 * <tr><td>A=0</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
253 * <tr><td>A=0</td><td>merge(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
254 * <tr><td>A=0</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
256 * <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>
257 * <tr><td>A=0</td><td>delete(A)</td><td>merge(A,2)</td><td>A=2</td></tr>
260 * <h4>Change compatibility of subtrees</h4>
262 * Following table shows state changes and failures between two concurrent transactions,
263 * which are based on same initial state, Tx 1 completes successfully
264 * before Tx 2 is submitted.
267 * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
269 * <tr><td>Empty</td><td>put(TOP,[])</td><td>put(TOP,[])</td><td>Tx 2 will fail, state is TOP=[]</td></tr>
270 * <tr><td>Empty</td><td>put(TOP,[])</td><td>merge(TOP,[])</td><td>TOP=[]</td></tr>
272 * <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>
273 * <tr><td>Empty</td><td>put(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>
275 * <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>
276 * <tr><td>Empty</td><td>merge(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>
278 * <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>
279 * <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>
280 * <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>
281 * <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>
282 * <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>
283 * <tr><td>TOP=[]</td><td>delete(TOP)</td><td>merge(TOP,[BAR=1])</td><td>state is TOP=[BAR=1]</td></tr>
285 * <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>
286 * <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>
287 * <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>
288 * <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>
289 * <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>
290 * <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>
292 * <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>
293 * <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>
294 * <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>
295 * <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>
296 * <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>
297 * <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>
301 * <h3>Examples of failure scenarios</h3>
303 * <h4>Conflict of two transactions</h4>
305 * This example illustrates two concurrent transactions, which derived from
306 * same initial state of data tree and proposes conflicting modifications.
309 * txA = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
310 * txB = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
312 * txA.put(CONFIGURATION, PATH, A); // writes to PATH value A
313 * txB.put(CONFIGURATION, PATH, B) // writes to PATH value B
315 * ListenableFuture futureA = txA.commit(); // transaction A is sealed and committed
316 * ListenebleFuture futureB = txB.commit(); // transaction B is sealed and committed
319 * Commit of transaction A will be processed asynchronously and data tree
320 * will be updated to contain value <code>A</code> for <code>PATH</code>.
321 * Returned {@link ListenableFuture} will successfully complete once
322 * state is applied to data tree.
324 * Commit of Transaction B will fail, because previous transaction also
325 * modified path in a concurrent way. The state introduced by transaction B
326 * will not be applied. Returned {@link ListenableFuture} object will fail
327 * with {@link OptimisticLockFailedException} exception, which indicates to
328 * client that concurrent transaction prevented the submitted transaction from being
331 * @return a CheckFuture containing the result of the commit. The Future blocks until the
332 * commit operation is complete. A successful commit returns nothing. On failure,
333 * the Future will fail with a {@link TransactionCommitFailedException} or an exception
334 * derived from TransactionCommitFailedException.
336 * @throws IllegalStateException
337 * if the transaction is not {@link TransactionStatus#NEW}
339 CheckedFuture<Void,TransactionCommitFailedException> submit();
342 * @deprecated Use {@link #submit()} instead.
345 ListenableFuture<RpcResult<TransactionStatus>> commit();