X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-common-api%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fmd%2Fsal%2Fcommon%2Fapi%2Fdata%2FAsyncDataTransactionFactory.java;h=a558b96b2d56fa26658741d8ee11ac63f3e735a3;hb=cbe83ca3074fa0182d4f079f528bb710a997ced7;hp=732fed0f3f482466ee3a4acb682b73f6826ea8ea;hpb=d5759c52d69ba8725d9bbdc18e81848f319861d1;p=controller.git

diff --git a/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncDataTransactionFactory.java b/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncDataTransactionFactory.java
index 732fed0f3f..a558b96b2d 100644
--- a/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncDataTransactionFactory.java
+++ b/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncDataTransactionFactory.java
@@ -9,12 +9,110 @@ package org.opendaylight.controller.md.sal.common.api.data;
 
 import org.opendaylight.yangtools.concepts.Path;
 
+/**
+ * A factory which allocates new transactions to operate on the data
+ * tree.
+ *
+ * <p>
+ * <b>Note:</b> This interface is not intended to be used directly, but rather
+ * via subinterfaces which introduces additional semantics to allocated
+ * transactions.
+ * <ul>
+ * <li> {@link AsyncDataBroker}
+ * <li> {@link TransactionChain}
+ * </ul>
+ *
+ * <p>
+ * All operations on the data tree are performed via one of the transactions:
+ * <ul>
+ * <li>Read-Only - allocated using {@link #newReadOnlyTransaction()}
+ * <li>Write-Only - allocated using {@link #newWriteOnlyTransaction()}
+ * <li>Read-Write - allocated using {@link #newReadWriteTransaction()}
+ * </ul>
+ *
+ * <p>
+ * These transactions provides a stable isolated view of the data tree, which is
+ * guaranteed to be not affected by other concurrent transactions, until
+ * transaction is committed.
+ *
+ * <p>
+ * For a detailed explanation of how transaction are isolated and how transaction-local
+ * changes are committed to global data tree, see
+ * {@link AsyncReadTransaction}, {@link AsyncWriteTransaction},
+ * {@link AsyncReadWriteTransaction} and {@link AsyncWriteTransaction#commit()}.
+ *
+ * <p>
+ * It is strongly recommended to use the type of transaction, which
+ * provides only the minimal capabilities you need. This allows for
+ * optimizations at the data broker / data store level. For example,
+ * implementations may optimize the transaction for reading if they know ahead
+ * of time that you only need to read data - such as not keeping additional meta-data,
+ * which may be required for write transactions.
+ *<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.
+ *
+ * @see AsyncDataBroker
+ * @see TransactionChain
+ *
+ * @param <P>
+ *            Type of path (subtree identifier), which represents location in
+ *            tree
+ * @param <D>
+ *            Type of data (payload), which represents data payload
+ */
 public interface AsyncDataTransactionFactory<P extends Path<P>, D> {
 
-    AsyncReadTransaction<P, D> newReadOnlyTransaction();
+    /**
+     * Allocates a new read-only transaction which provides an immutable snapshot of
+     * the data tree.
+     *<p>
+     * The view of data tree is an immutable snapshot of current data tree state when
+     * transaction was allocated.
+     *
+     * @return new read-only transaction
+     */
+    AsyncReadOnlyTransaction<P, D> newReadOnlyTransaction();
 
+    /**
+     * Allocates new read-write transaction which provides a mutable view of the data
+     * tree.
+     *
+     * <p>
+     * Preconditions for mutation of data tree are captured from the snapshot of
+     * data tree state, when the transaction is allocated. If data was
+     * changed during transaction in an incompatible way then the commit of this transaction
+     * will fail. See {@link AsyncWriteTransaction#commit()} for more
+     * details about conflicting and not-conflicting changes and
+     * failure scenarios.
+     *
+     * @return new read-write transaction
+     */
     AsyncReadWriteTransaction<P, D> newReadWriteTransaction();
 
-    AsyncWriteTransaction<P,D> newWriteOnlyTransaction();
+    /**
+     * Allocates new write-only transaction based on latest state of data
+     * tree.
+     *
+     * <p>
+     * Preconditions for mutation of data tree are captured from the snapshot of
+     * data tree state, when the transaction is allocated. If data was
+     * changed during transaction in an incompatible way then the commit of this transaction
+     * will fail. See {@link AsyncWriteTransaction#commit()} for more
+     * details about conflicting and not-conflicting changes and
+     * failure scenarios.
+     *
+     * <p>
+     * Since this transaction does not provide a view of the data it SHOULD BE
+     * used only by callers which are exclusive writers (exporters of data)
+     * to the subtree they modify. This prevents optimistic
+     * lock failures as described in {@link AsyncWriteTransaction#commit()}.
+     * <p>
+     * Exclusivity of writers to particular subtree SHOULD BE enforced by
+     * external locking mechanism.
+     *
+     * @return new write-only transaction
+     */
+    AsyncWriteTransaction<P, D> newWriteOnlyTransaction();
 
 }