X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-common-api%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fmd%2Fsal%2Fcommon%2Fapi%2Fdata%2FAsyncWriteTransaction.java;h=f7eae27320107ef6a90696ff73f2cf40b3c99fde;hp=82c48d2ddb27e657c12cb9c8f56f49997923b370;hb=d7d5c4d3e7eaed528961081718c47a0960517ace;hpb=c22465be2000037e89ec812f901fe7f608e58093 diff --git a/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncWriteTransaction.java b/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncWriteTransaction.java index 82c48d2ddb..f7eae27320 100644 --- a/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncWriteTransaction.java +++ b/opendaylight/md-sal/sal-common-api/src/main/java/org/opendaylight/controller/md/sal/common/api/data/AsyncWriteTransaction.java @@ -13,56 +13,124 @@ import org.opendaylight.yangtools.yang.common.RpcResult; import com.google.common.util.concurrent.ListenableFuture; -public interface AsyncWriteTransaction

, D> extends AsyncTransaction { +/** + * Write transaction provides mutation capabilities for a data tree. + * + *

+ * 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. + *

+ * 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. + *

+ * 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 submits it to be + * processed and applied to global conceptual data tree. + *

+ * 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. + * + * + *

+ * Implementation Note: This interface is not intended to be implemented + * by users of MD-SAL, but only to be consumed by them. + * + * @param

+ * Type of path (subtree identifier), which represents location in + * tree + * @param + * Type of data (payload), which represents data payload + */ +public interface AsyncWriteTransaction

, D> extends AsyncTransaction { /** - * Cancels transaction. + * Cancels the transaction. + * + * Transactions can only be cancelled if it's status is + * {@link TransactionStatus#NEW} or {@link TransactionStatus#SUBMITED} * - * Transaction could be only cancelled if it's status - * is {@link TransactionStatus#NEW} or {@link TransactionStatus#SUBMITED} + * Invoking cancel() on {@link TransactionStatus#FAILED} or + * {@link TransactionStatus#CANCELED} will have no effect, and transaction + * is considered cancelled. * - * Invoking cancel() on {@link TransactionStatus#FAILED} or {@link TransactionStatus#CANCELED} - * will have no effect. + * Invoking cancel() on finished transaction (future returned by {@link #commit()} + * already completed with {@link TransactionStatus#COMMITED}) will always + * fail (return false). * - * @throws IllegalStateException If transaction status is {@link TransactionStatus#COMMITED} + * @return false if the task could not be cancelled, + * typically because it has already completed normally; + * true otherwise * */ - public void cancel(); + public boolean cancel(); /** - * Store a piece of data at specified path. This acts as a add / replace operation, - * which is to say that whole subtree will be replaced by specified path. + * Store a piece of data at specified path. This acts as an add / replace + * operation, which is to say that whole subtree will be replaced by + * specified path. Performing the following put operations: + * + * 

+     * 1) container { list [ a ] }
+     * 2) container { list [ b ] }
+     *
+ * + * will result in the following data being present: + * + * 
+     * container { list [ b ] }
+     *
* - * If you need add or merge of current object with specified use {@link #merge(LogicalDatastoreType, Path, Object)} * - * @param store Logical data store which should be modified - * @param path Data object path - * @param data Data object to be written to specified path - * @throws IllegalStateException if the transaction is no longer {@link TransactionStatus#NEW} + * If you need to make sure that a parent object exists, but you do not want modify + * its preexisting state by using put, consider using + * {@link #merge(LogicalDatastoreType, Path, Object)} + * + * @param store + * Logical data store which should be modified + * @param path + * Data object path + * @param data + * Data object to be written to specified path + * @throws IllegalStateException + * if the transaction is no longer {@link TransactionStatus#NEW} */ public void put(LogicalDatastoreType store, P path, D data); /** - * Store a piece of data at specified path. This acts as a merge operation, + * Store a piece of data at the specified path. This acts as a merge operation, * which is to say that 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. Performing the following put operations: + * its child lists will be merged. Performing the following merge + * operations: * + * 
      * 1) container { list [ a ] }
      * 2) container { list [ b ] }
+     *
* * will result in the following data being present: * + * 
      * container { list [ a, b ] }
+     *
* - * This also means that storing the container will preserve any augmentations - * which have been attached to it. - * - * If you require an explicit replace operation, use {@link #put(LogicalDatastoreType, Path, Object)} instead. + * This also means that storing the container will preserve any + * augmentations which have been attached to it. + *

+ * If you require an explicit replace operation, use + * {@link #put(LogicalDatastoreType, Path, Object)} instead. * - * @param store Logical data store which should be modified - * @param path Data object path - * @param data Data object to be written to specified path - * @throws IllegalStateException if the transaction is no longer {@link TransactionStatus#NEW} + * @param store + * Logical data store which should be modified + * @param path + * Data object path + * @param data + * Data object to be written to specified path + * @throws IllegalStateException + * if the transaction is no longer {@link TransactionStatus#NEW} */ public void merge(LogicalDatastoreType store, P path, D data); @@ -70,51 +138,168 @@ public interface AsyncWriteTransaction

, D> extends AsyncTrans * Remove a piece of data from specified path. This operation does not fail * if the specified path does not exist. * - * @param store Logical data store which should be modified - * @param path Data object path - * @throws IllegalStateException if the transaction is no longer {@link TransactionStatus#NEW} + * @param store + * Logical data store which should be modified + * @param path + * Data object path + * @throws IllegalStateException + * if the transaction is no longer {@link TransactionStatus#NEW} */ public void delete(LogicalDatastoreType store, P path); /** + * Submits transaction to be applied to update logical data tree. + *

+ * This call logically seals the transaction, which prevents the client from + * further changing data tree using this transaction. Any subsequent calls to + * {@link #put(LogicalDatastoreType, Path, Object)}, + * {@link #merge(LogicalDatastoreType, Path, Object)} or + * {@link #delete(LogicalDatastoreType, Path)} will fail with + * {@link IllegalStateException}. * - * Closes transaction and resources allocated to the transaction. - * - * This call does not change Transaction status. Client SHOULD - * explicitly {@link #commit()} or {@link #cancel()} transaction. - * - * @throws IllegalStateException if the transaction has not been - * updated by invoking {@link #commit()} or {@link #cancel()}. - */ - @Override - public void close(); - - /** - * Initiates a commit of modification. This call logically seals the - * transaction, preventing any the client from interacting with the - * data stores. The transaction is marked as {@link TransactionStatus#SUBMITED} - * and enqueued into the data store backed for processing. + * The transaction is marked as {@link TransactionStatus#SUBMITED} and + * enqueued into the data store backed for processing. * *

- * The successful commit changes the state of the system and may affect - * several components. + * Whether or not the commit is successful is determined by versioning + * of data tree and validation of registered commit participants + * {@link AsyncConfigurationCommitHandler} + * if transaction changes {@link LogicalDatastoreType#CONFIGURATION} data tree. + *

+ * The effects of successful commit of data depends on + * other data change listeners {@link AsyncDataChangeListener} and + * {@link AsyncConfigurationCommitHandler}, which was registered to the + * same {@link AsyncDataBroker}, to which this transaction belongs. * + *

Failure scenarios

*

- * The effects of successful commit of data are described in the - * specifications and YANG models describing the Provider components of - * controller. It is assumed that Consumer has an understanding of this - * changes. - * - * @see DataCommitHandler for further information how two-phase commit is - * processed. - * @param store Identifier of the store, where commit should occur. + * Transaction may fail because of multiple reasons, such as + *

+ * + *

Change compatibility

+ * + * 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. + * + *

Change compatibility of leafs, leaf-list items

+ * + * 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 submitted. + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + *
Initial stateTx 1Tx 2Result
Emptyput(A,1)put(A,2)Tx 2 will fail, state is A=1
Emptyput(A,1)merge(A,2)A=2
Emptymerge(A,1)put(A,2)Tx 2 will fail, state is A=1
Emptymerge(A,1)merge(A,2)A=2
A=0put(A,1)put(A,2)Tx 2 will fail, A=1
A=0put(A,1)merge(A,2)A=2
A=0merge(A,1)put(A,2)Tx 2 will fail, A=1
A=0merge(A,1)merge(A,2)A=2
A=0delete(A)put(A,2)Tx 2 will fail, A does not exists
A=0delete(A)merge(A,2)A=2
+ * + *

Change compatibility of subtrees

+ * + * 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 submitted. + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + *
Initial stateTx 1Tx 2Result
Emptyput(TOP,[])put(TOP,[])Tx 2 will fail, state is TOP=[]
Emptyput(TOP,[])merge(TOP,[])TOP=[]
Emptyput(TOP,[FOO=1])put(TOP,[BAR=1])Tx 2 will fail, state is TOP=[FOO=1]
Emptyput(TOP,[FOO=1])merge(TOP,[BAR=1])TOP=[FOO=1,BAR=1]
Emptymerge(TOP,[FOO=1])put(TOP,[BAR=1])Tx 2 will fail, state is TOP=[FOO=1]
Emptymerge(TOP,[FOO=1])merge(TOP,[BAR=1])TOP=[FOO=1,BAR=1]
TOP=[]put(TOP,[FOO=1])put(TOP,[BAR=1])Tx 2 will fail, state is TOP=[FOO=1]
TOP=[]put(TOP,[FOO=1])merge(TOP,[BAR=1])state is TOP=[FOO=1,BAR=1]
TOP=[]merge(TOP,[FOO=1])put(TOP,[BAR=1])Tx 2 will fail, state is TOP=[FOO=1]
TOP=[]merge(TOP,[FOO=1])merge(TOP,[BAR=1])state is TOP=[FOO=1,BAR=1]
TOP=[]delete(TOP)put(TOP,[BAR=1])Tx 2 will fail, state is empty store
TOP=[]delete(TOP)merge(TOP,[BAR=1])state is TOP=[BAR=1]
TOP=[]put(TOP/FOO,1)put(TOP/BAR,1])state is TOP=[FOO=1,BAR=1]
TOP=[]put(TOP/FOO,1)merge(TOP/BAR,1)state is TOP=[FOO=1,BAR=1]
TOP=[]merge(TOP/FOO,1)put(TOP/BAR,1)state is TOP=[FOO=1,BAR=1]
TOP=[]merge(TOP/FOO,1)merge(TOP/BAR,1)state is TOP=[FOO=1,BAR=1]
TOP=[]delete(TOP)put(TOP/BAR,1)Tx 2 will fail, state is empty store
TOP=[]delete(TOP)merge(TOP/BAR,1]Tx 2 will fail, state is empty store
TOP=[FOO=1]put(TOP/FOO,2)put(TOP/BAR,1)state is TOP=[FOO=2,BAR=1]
TOP=[FOO=1]put(TOP/FOO,2)merge(TOP/BAR,1)state is TOP=[FOO=2,BAR=1]
TOP=[FOO=1]merge(TOP/FOO,2)put(TOP/BAR,1)state is TOP=[FOO=2,BAR=1]
TOP=[FOO=1]merge(TOP/FOO,2)merge(TOP/BAR,1)state is TOP=[FOO=2,BAR=1]
TOP=[FOO=1]delete(TOP/FOO)put(TOP/BAR,1)state is TOP=[BAR=1]
TOP=[FOO=1]delete(TOP/FOO)merge(TOP/BAR,1]state is TOP=[BAR=1]
+ * + * + *

Examples of failure scenarios

+ * + *

Conflict of two transactions

+ * + * This example illustrates two concurrent transactions, which derived from + * same initial state of data tree and proposes conflicting modifications. + * + * 
+     * 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
+     *
+ * + * Commit of transaction A will be processed asynchronously and data tree + * will be updated to contain value A for PATH. + * Returned {@link ListenableFuture} 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 ListenableFuture} object will fail + * with {@link OptimisticLockFailedException} exception, which indicates to + * client that concurrent transaction prevented the submitted transaction from being + * applied. + * * @return Result of the Commit, containing success information or list of * encountered errors, if commit was not successful. The Future * blocks until {@link TransactionStatus#COMMITED} is reached. - * Future will fail with {@link TransactionCommitFailedException} - * if Commit of this transaction failed. + * Future will fail with {@link TransactionCommitFailedException} if + * Commit of this transaction failed. TODO: Usability: Consider + * change from ListenableFuture to + * {@link com.google.common.util.concurrent.CheckedFuture} which + * will throw {@link TransactionCommitFailedException}. * - * @throws IllegalStateException if the transaction is not {@link TransactionStatus#NEW} + * @throws IllegalStateException + * if the transaction is not {@link TransactionStatus#NEW} */ public ListenableFuture> commit();