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 com.google.common.util.concurrent.CheckedFuture;
11 import com.google.common.util.concurrent.FluentFuture;
12 import com.google.common.util.concurrent.ListenableFuture;
13 import com.google.common.util.concurrent.MoreExecutors;
14 import javax.annotation.CheckReturnValue;
15 import org.eclipse.jdt.annotation.NonNull;
16 import org.opendaylight.mdsal.common.api.CommitInfo;
17 import org.opendaylight.yangtools.concepts.Path;
20 * Write transaction provides mutation capabilities for a data tree.
23 * Initial state of write transaction is a stable snapshot of the current data tree.
24 * The state is captured when the transaction is created and its state and underlying
25 * data tree are not affected by other concurrently running transactions.
28 * Write transactions are isolated from other concurrent write transactions. All
29 * writes are local to the transaction and represent only a proposal of state
30 * change for the data tree and it is not visible to any other concurrently running
34 * Applications make changes to the local data tree in the transaction by via the
35 * <b>put</b>, <b>merge</b>, and <b>delete</b> operations.
37 * <h2>Put operation</h2>
38 * Stores a piece of data at a specified path. This acts as an add / replace
39 * operation, which is to say that whole subtree will be replaced by the
43 * Performing the following put operations:
46 * 1) container { list [ a ] }
47 * 2) container { list [ b ] }
51 * will result in the following data being present:
54 * container { list [ b ] }
56 * <h2>Merge operation</h2>
57 * Merges a piece of data with the existing data at a specified path. Any pre-existing data
58 * which is not explicitly overwritten will be preserved. This means that if you store a container,
59 * its child lists will be merged.
62 * Performing the following merge operations:
65 * 1) container { list [ a ] }
66 * 2) container { list [ b ] }
70 * will result in the following data being present:
73 * container { list [ a, b ] }
77 * This also means that storing the container will preserve any
78 * augmentations which have been attached to it.
80 * <h2>Delete operation</h2>
81 * Removes a piece of data from a specified path.
84 * After applying changes to the local data tree, applications publish the changes proposed in the
85 * transaction by calling {@link #submit} on the transaction. This seals the transaction
86 * (preventing any further writes using this transaction) and submits it to be
87 * processed and applied to global conceptual data tree.
90 * The transaction commit may fail due to a concurrent transaction modifying and committing data in
91 * an incompatible way. See {@link #submit} for more concrete commit failure examples.
94 * <b>Implementation Note:</b> This interface is not intended to be implemented
95 * by users of MD-SAL, but only to be consumed by them.
98 * Type of path (subtree identifier), which represents location in
101 * Type of data (payload), which represents data payload
103 public interface AsyncWriteTransaction<P extends Path<P>, D> extends AsyncTransaction<P, D> {
105 * Cancels the transaction.
108 * Transactions can only be cancelled if it's state is new or submitted.
111 * Invoking cancel() on a failed or cancelled transaction will have no effect, and transaction
112 * is considered cancelled.
115 * Invoking cancel() on a finished transaction (future returned by {@link #submit()} already completed will always
116 * fail (return false).
118 * @return <tt>false</tt> if the task could not be cancelled, typically because it has already completed normally
119 * <tt>true</tt> otherwise
125 * Removes a piece of data from specified path. This operation does not fail
126 * if the specified path does not exist.
129 * Logical data store which should be modified
132 * @throws IllegalStateException
133 * if the transaction as already been submitted or cancelled
135 void delete(LogicalDatastoreType store, P path);
138 * Submits this transaction to be asynchronously applied to update the logical data tree.
139 * The returned CheckedFuture conveys the result of applying the data changes.
142 * <b>Note:</b> It is strongly recommended to process the CheckedFuture result in an asynchronous
143 * manner rather than using the blocking get() method. See example usage below.
146 * This call logically seals the transaction, which prevents the client from
147 * further changing data tree using this transaction. Any subsequent calls to
148 * {@link #delete(LogicalDatastoreType, Path)} will fail with
149 * {@link IllegalStateException}.
152 * The transaction is marked as submitted and enqueued into the data store back-end for processing.
155 * Whether or not the commit is successful is determined by versioning
156 * of the data tree and validation of registered commit participants
157 * ({@link AsyncConfigurationCommitHandler}) if the transaction changes the data tree.
160 * The effects of a successful commit of data depends on data change listeners
161 * ({@link AsyncDataChangeListener}) and commit participants
162 * ({@link AsyncConfigurationCommitHandler}) that are registered with the data broker.
164 * <h3>Example usage:</h3>
166 * private void doWrite( final int tries ) {
167 * WriteTransaction writeTx = dataBroker.newWriteOnlyTransaction();
169 * MyDataObject data = ...;
170 * InstanceIdentifier<MyDataObject> path = ...;
171 * writeTx.put( LogicalDatastoreType.OPERATIONAL, path, data );
173 * Futures.addCallback( writeTx.submit(), new FutureCallback<Void>() {
174 * public void onSuccess( Void result ) {
178 * public void onFailure( Throwable t ) {
179 * if( t instanceof OptimisticLockFailedException ) {
180 * if( ( tries - 1 ) > 0 ) {
182 * doWrite( tries - 1 );
187 * // failed due to another type of TransactionCommitFailedException.
194 * <h2>Failure scenarios</h2>
197 * Transaction may fail because of multiple reasons, such as
199 * <li>Another transaction finished earlier and modified the same node in a
200 * non-compatible way (see below). In this case the returned future will fail with an
201 * {@link OptimisticLockFailedException}. It is the responsibility of the
202 * caller to create a new transaction and submit the same modification again in
203 * order to update data tree. <i><b>Warning</b>: In most cases, retrying after an
204 * OptimisticLockFailedException will result in a high probability of success.
205 * However, there are scenarios, albeit unusual, where any number of retries will
206 * not succeed. Therefore it is strongly recommended to limit the number of retries (2 or 3)
207 * to avoid an endless loop.</i>
209 * <li>Data change introduced by this transaction did not pass validation by
210 * commit handlers or data was incorrectly structured. Returned future will
211 * fail with a {@link DataValidationFailedException}. User should not retry to
212 * create new transaction with same data, since it probably will fail again.
216 * <h3>Change compatibility</h3>
219 * There are several sets of changes which could be considered incompatible
220 * between two transactions which are derived from same initial state.
221 * Rules for conflict detection applies recursively for each subtree
224 * <h4>Change compatibility of leafs, leaf-list items</h4>
227 * Following table shows state changes and failures between two concurrent transactions,
228 * which are based on same initial state, Tx 1 completes successfully
229 * before Tx 2 is submitted.
232 * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
233 * <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>
234 * <tr><td>Empty</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
236 * <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>
237 * <tr><td>Empty</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
240 * <tr><td>A=0</td><td>put(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
241 * <tr><td>A=0</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
242 * <tr><td>A=0</td><td>merge(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
243 * <tr><td>A=0</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
245 * <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>
246 * <tr><td>A=0</td><td>delete(A)</td><td>merge(A,2)</td><td>A=2</td></tr>
249 * <h4>Change compatibility of subtrees</h4>
252 * Following table shows state changes and failures between two concurrent transactions,
253 * which are based on same initial state, Tx 1 completes successfully
254 * before Tx 2 is submitted.
257 * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
259 * <tr><td>Empty</td><td>put(TOP,[])</td><td>put(TOP,[])</td><td>Tx 2 will fail, state is TOP=[]</td></tr>
260 * <tr><td>Empty</td><td>put(TOP,[])</td><td>merge(TOP,[])</td><td>TOP=[]</td></tr>
262 * <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]
264 * <tr><td>Empty</td><td>put(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>
266 * <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]
268 * <tr><td>Empty</td><td>merge(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>
270 * <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]
272 * <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>
273 * <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]
275 * <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>
276 * <tr><td>TOP=[]</td><td>delete(TOP)</td><td>put(TOP,[BAR=1])</td><td>Tx 2 will fail, state is empty store
278 * <tr><td>TOP=[]</td><td>delete(TOP)</td><td>merge(TOP,[BAR=1])</td><td>state is TOP=[BAR=1]</td></tr>
280 * <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>
281 * <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>
282 * <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>
283 * <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>
284 * <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>
285 * <tr><td>TOP=[]</td><td>delete(TOP)</td><td>merge(TOP/BAR,1]</td><td>Tx 2 will fail, state is empty store
288 * <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>
289 * <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>
290 * <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>
291 * <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]
293 * <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>
294 * <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>
298 * <h3>Examples of failure scenarios</h3>
300 * <h4>Conflict of two transactions</h4>
303 * This example illustrates two concurrent transactions, which derived from
304 * same initial state of data tree and proposes conflicting modifications.
307 * txA = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
308 * txB = broker.newWriteTransaction(); // allocates new transaction, data tree is empty
310 * txA.put(CONFIGURATION, PATH, A); // writes to PATH value A
311 * txB.put(CONFIGURATION, PATH, B) // writes to PATH value B
313 * ListenableFuture futureA = txA.submit(); // transaction A is sealed and submitted
314 * ListenebleFuture futureB = txB.submit(); // transaction B is sealed and submitted
318 * Commit of transaction A will be processed asynchronously and data tree
319 * will be updated to contain value <code>A</code> for <code>PATH</code>.
320 * Returned {@link ListenableFuture} will successfully complete once
321 * 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 new
338 * @deprecated Use {@link #commit()} instead.
341 CheckedFuture<Void,TransactionCommitFailedException> submit();
344 * Submits this transaction to be asynchronously applied to update the logical data tree. The returned
345 * {@link FluentFuture} conveys the result of applying the data changes.
348 * This call logically seals the transaction, which prevents the client from further changing the data tree using
349 * this transaction. Any subsequent calls to <code>put(LogicalDatastoreType, Path, Object)</code>,
350 * <code>merge(LogicalDatastoreType, Path, Object)</code>, <code>delete(LogicalDatastoreType, Path)</code> will fail
351 * with {@link IllegalStateException}. The transaction is marked as submitted and enqueued into the data store
352 * back-end for processing.
355 * Whether or not the commit is successful is determined by versioning of the data tree and validation of registered
356 * commit participants if the transaction changes the data tree.
359 * The effects of a successful commit of data depends on listeners and commit participants that are registered with
363 * A successful commit produces implementation-specific {@link CommitInfo} structure, which is used to communicate
364 * post-condition information to the caller. Such information can contain commit-id, timing information or any
365 * other information the implementation wishes to share.
367 * @return a FluentFuture containing the result of the commit information. The Future blocks until the commit
368 * operation is complete. A successful commit returns nothing. On failure, the Future will fail with a
369 * {@link TransactionCommitFailedException} or an exception derived from TransactionCommitFailedException.
370 * @throws IllegalStateException if the transaction is already committed or was canceled.
373 default @NonNull FluentFuture<? extends @NonNull CommitInfo> commit() {
374 return FluentFuture.from(submit()).transformAsync(ignored -> CommitInfo.emptyFluentFuture(),
375 MoreExecutors.directExecutor());