import org.opendaylight.yangtools.concepts.Path;
/**
- * Transaction enabling client to have combined transaction,
- * which provides read and write capabilities.
+ * Transaction enabling a client to have a combined read/write capabilities.
*
+ * <p>
+ * The initial state of the write transaction is stable snapshot of current data tree
+ * state captured when transaction was created and it's state and underlying
+ * data tree are not affected by other concurrently running transactions.
*
- * @param <P> Path Type
- * @param <D> Data Type
+ * <p>
+ * Write transactions are isolated from other concurrent write transactions. All
+ * writes are local to the transaction and represents only a proposal of state
+ * change for data tree and it is not visible to any other concurrently running
+ * transactions.
+ *
+ * <p>
+ * Applications publish the changes proposed in the transaction by calling {@link #submit}
+ * on the transaction. This seals the transaction
+ * (preventing any further writes using this transaction) and submits 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 #submit()} for more concrete commit failure examples.
+ *
+ * <b>Implementation Note:</b> This interface is not intended to be implemented
+ * by users of MD-SAL, but only to be consumed by them.
+ *
+ * <h2>Examples</h2>
+ *
+ * <h3>Transaction local state</h3>
+ *
+ * <p>
+ * Let assume initial state of data tree for <code>PATH</code> is <code>A</code>
+ * .
+ *
+ * <pre>
+ * txWrite = broker.newReadWriteTransaction(); // concurrent write transaction
+ *
+ * txWrite.read(OPERATIONAL,PATH).get() // will return Optional containing A
+ * txWrite.put(OPERATIONAL,PATH,B); // writes B to PATH
+ * txWrite.read(OPERATIONAL,PATH).get() // will return Optional Containing B
+ *
+ * txWrite.commit().get(); // data tree is updated, PATH contains B
+ *
+ * tx1afterCommit = broker.newReadOnlyTransaction(); // read Transaction is snapshot of new state
+ * tx1afterCommit.read(OPERATIONAL,PATH).get(); // returns Optional containing B
+ * </pre>
+ *
+ * <p>
+ * As you could see read-write transaction provides capabilities as
+ * {@link AsyncWriteTransaction} but also allows for reading proposed changes as
+ * if they already happened.
+ *
+ * <h3>Transaction isolation (read transaction, read-write transaction)</h3> Let
+ * assume initial state of data tree for <code>PATH</code> is <code>A</code>.
+ *
+ * <pre>
+ * txRead = broker.newReadOnlyTransaction(); // read Transaction is snapshot of data
+ * txWrite = broker.newReadWriteTransaction(); // concurrent write transaction
+ *
+ * txRead.read(OPERATIONAL,PATH).get(); // will return Optional containing A
+ * txWrite.read(OPERATIONAL,PATH).get() // will return Optional containing A
+ *
+ * txWrite.put(OPERATIONAL,PATH,B); // writes B to PATH
+ * txWrite.read(OPERATIONAL,PATH).get() // will return Optional Containing B
+ *
+ * txRead.read(OPERATIONAL,PATH).get(); // concurrent read transaction still returns
+ * // Optional containing A
+ *
+ * txWrite.commit().get(); // data tree is updated, PATH contains B
+ * txRead.read(OPERATIONAL,PATH).get(); // still returns Optional containing A
+ *
+ * tx1afterCommit = broker.newReadOnlyTransaction(); // read Transaction is snapshot of new state
+ * tx1afterCommit.read(OPERATIONAL,PATH).get(); // returns Optional containing B
+ * </pre>
+ *
+ * <h3>Transaction isolation (2 concurrent read-write transactions)</h3> Let
+ * assume initial state of data tree for <code>PATH</code> is <code>A</code>.
+ *
+ * <pre>
+ * tx1 = broker.newReadWriteTransaction(); // read Transaction is snapshot of data
+ * tx2 = broker.newReadWriteTransaction(); // concurrent write transaction
+ *
+ * tx1.read(OPERATIONAL,PATH).get(); // will return Optional containing A
+ * tx2.read(OPERATIONAL,PATH).get() // will return Optional containing A
+ *
+ * tx2.put(OPERATIONAL,PATH,B); // writes B to PATH
+ * tx2.read(OPERATIONAL,PATH).get() // will return Optional Containing B
+ *
+ * tx1.read(OPERATIONAL,PATH).get(); // tx1 read-write transaction still sees Optional
+ * // containing A since is isolated from tx2
+ * tx1.put(OPERATIONAL,PATH,C); // writes C to PATH
+ * tx1.read(OPERATIONAL,PATH).get() // will return Optional Containing C
+ *
+ * tx2.read(OPERATIONAL,PATH).get() // tx2 read-write transaction still sees Optional
+ * // containing B since is isolated from tx1
+ *
+ * tx2.commit().get(); // data tree is updated, PATH contains B
+ * tx1.read(OPERATIONAL,PATH).get(); // still returns Optional containing C since is isolated from tx2
+ *
+ * tx1afterCommit = broker.newReadOnlyTransaction(); // read Transaction is snapshot of new state
+ * tx1afterCommit.read(OPERATIONAL,PATH).get(); // returns Optional containing B
+ *
+ * tx1.commit() // Will fail with OptimisticLockFailedException
+ * // which means concurrent transaction changed the same PATH
+ *
+ * </pre>
+ *
+ * <p>
+ * <b>Note:</b> examples contains blocking calls on future only to illustrate
+ * that action happened after other asynchronous action. Use of blocking call
+ * {@link com.google.common.util.concurrent.ListenableFuture#get()} is discouraged for most uses and you should
+ * use {@link com.google.common.util.concurrent.Futures#addCallback(com.google.common.util.concurrent.ListenableFuture,
+ * com.google.common.util.concurrent.FutureCallback, java.util.concurrent.Executor)}
+ * or other functions from {@link com.google.common.util.concurrent.Futures} to
+ * register more specific listeners.
+ *
+ * @see AsyncReadTransaction
+ * @see AsyncWriteTransaction
+ *
+ * @param <P>
+ * Type of path (subtree identifier), which represents location in
+ * tree
+ * @param <D>
+ * Type of data (payload), which represents data payload
*/
+@Deprecated
public interface AsyncReadWriteTransaction<P extends Path<P>, D> extends AsyncReadTransaction<P, D>,
AsyncWriteTransaction<P, D> {
Code Review / controller.git / blobdiff