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%2FAsyncWriteTransaction.java;h=e2734eaddc4845396e3d866dec8d918ac9fe4bca;hb=bef0749bb2517eaae6a501be501e16a7d3905045;hp=35b9914a120dc289dbac3ff8c8f7ae85176f5be4;hpb=9fda938ef6dc037ef1c5a9fbed25469d4a532150;p=controller.git 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 35b9914a12..e2734eaddc 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 @@ -7,62 +7,124 @@ */ package org.opendaylight.controller.md.sal.common.api.data; -import java.util.concurrent.Future; - import org.opendaylight.controller.md.sal.common.api.TransactionStatus; import org.opendaylight.yangtools.concepts.Path; import org.opendaylight.yangtools.yang.common.RpcResult; -public interface AsyncWriteTransaction
, D> extends AsyncTransaction
{ +import com.google.common.util.concurrent.ListenableFuture; + +/** + * 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 , D> extends AsyncTransaction {
/**
- * Cancels transaction.
+ * Cancels the transaction.
*
- * Transaction could be only cancelled if it's status
- * is {@link TransactionStatus#NEW} or {@link TransactionStatus#SUBMITED}
+ * Transactions can only be 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.
+ * Invoking cancel() on {@link TransactionStatus#FAILED} or
+ * {@link TransactionStatus#CANCELED} will have no effect.
*
- * @throws IllegalStateException If transaction status is {@link TransactionStatus#COMMITED}
+ * @throws IllegalStateException
+ * If transaction status is {@link TransactionStatus#COMMITED}
*
*/
public void 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:
+ *
+ *
+ * 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);
@@ -70,9 +132,12 @@ 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);
@@ -80,40 +145,170 @@ public interface AsyncWriteTransaction , D> extends AsyncTrans
*
* Closes transaction and resources allocated to the transaction.
*
- * This call does not change Transaction status. Client SHOULD
- * explicitly {@link #commit()} or {@link #cancel()} 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()}.
+ * @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.
+ * 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}.
+ *
+ * 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.
*
+ *
- * 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
+ *
+ * 1) container { list [ a ] }
+ * 2) container { list [ b ] }
+ *
+ *
+ * will result in the following data being present:
*
- * If you need add or merge of current object with specified use {@link #merge(LogicalDatastoreType, Path, Object)}
+ *
+ * container { list [ b ] }
+ *
*
- * @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.
+ *Failure scenarios
*
+ *
+ *
+ * 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 state Tx 1 Tx 2 Result
+ * Empty put(A,1) put(A,2) Tx 2 will fail, state is A=1
+ *
+ * Empty put(A,1) merge(A,2) A=2
+ * Empty merge(A,1) put(A,2) Tx 2 will fail, state is A=1
+ *
+ *
+ * Empty merge(A,1) merge(A,2) A=2
+ * A=0 put(A,1) put(A,2) Tx 2 will fail, A=1
+ * A=0 put(A,1) merge(A,2) A=2
+ * A=0 merge(A,1) put(A,2) Tx 2 will fail, A=1
+ *
+ * A=0 merge(A,1) merge(A,2) A=2
+ * A=0 delete(A) put(A,2) Tx 2 will fail, A does not exists
+ * A=0 delete(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 state Tx 1 Tx 2 Result
+ * Empty put(TOP,[]) put(TOP,[]) Tx 2 will fail, state is TOP=[]
+ *
+ * Empty put(TOP,[]) merge(TOP,[]) TOP=[]
+ * Empty put(TOP,[FOO=1]) put(TOP,[BAR=1]) Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ * Empty put(TOP,[FOO=1]) merge(TOP,[BAR=1]) TOP=[FOO=1,BAR=1]
+ * Empty merge(TOP,[FOO=1]) put(TOP,[BAR=1]) Tx 2 will fail, state is TOP=[FOO=1]
+ *
+ * Empty merge(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} or
- * {@link TransactionStatus#FAILED} is reached.
- * @throws IllegalStateException if the transaction is not {@link TransactionStatus#NEW}
+ * blocks until {@link TransactionStatus#COMMITED} is reached.
+ * 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}
*/
- public Future