/**
* Create a transaction reading from the most recent committed state not later than the specified
* startTime.
*
* <p>Note: For an {@link IBigdataFederation}, a transaction does not start execution on all
* {@link IDataService}s at the same moment. Instead, the transaction startTime is assigned by the
* {@link ITransactionService} and then provided each time an {@link ITx} must be created for
* isolatation of resources accessible on a {@link IDataService}.
*
* @param transactionManager The local (client-side) transaction manager.
* @param resourceManager Provides access to named indices that are isolated by the transaction.
* @param startTime The transaction identifier
* @param readsOnCommitTime The timestamp of the commit point against which this transaction is
* reading.
* @see <a href="https://sourceforge.net/apps/trac/bigdata/ticket/266">Refactor native long tx id
* to thin object</a>
* @see <a href="http://sourceforge.net/apps/trac/bigdata/ticket/546" > Add cache for access to
* historical index views on the Journal by name and commitTime. </a>
*/
public Tx( //
final AbstractLocalTransactionManager localTransactionManager, //
final IResourceManager resourceManager, //
final long startTime,
final long readsOnCommitTime //
) {
if (localTransactionManager == null) throw new IllegalArgumentException();
if (resourceManager == null) throw new IllegalArgumentException();
this.readOnly = !TimestampUtility.isReadWriteTx(startTime);
// if (!TimestampUtility.isReadWriteTx(startTime)) {
//
// /*
// * Note: We only maintain local state for read-write transactions.
// */
//
// throw new IllegalArgumentException();
//
// }
// this.localTransactionManager = localTransactionManager;
this.indices = readOnly ? null : new ConcurrentHashMap<String, ILocalBTreeView>();
this.resourceManager = resourceManager;
this.startTime = startTime;
/*
* Note: On a new journal, the lastCommitTime is ZERO before the first
* commit point. In order to avoid having the ground state view be the
* UNISOLATED index view, we use a timestamp which is known to be before
* any valid timestamp (and which will be shared by any transaction
* started against an empty journal).
*
* Note: It might be better to put this logic into
* Journal#getLastCommitTime(). However, there are other callers for
* that method. By making the change here, we can guarantee that its
* scope is limited to only the code change made for the following
* ticket.
*
* @see <a href="http://sourceforge.net/apps/trac/bigdata/ticket/546" >
* Add cache for access to historical index views on the Journal by name
* and commitTime. </a>
*/
this.readsOnCommitTime = readsOnCommitTime == ITx.UNISOLATED ? 1 : readsOnCommitTime;
this.runState = RunState.Active;
// pre-compute the hash code for the transaction.
this.hashCode = Long.valueOf(startTime).hashCode();
localTransactionManager.activateTx(this);
// report event.
ResourceManager.openTx(startTime);
}
/**
* Return a named index. The index will be isolated at the same level as this transaction. Changes
* on the index will be made restart-safe iff the transaction successfully commits.
*
* @param name The name of the index.
* @return The named index or <code>null</code> if no index is registered under that name.
* @exception IllegalStateException if the transaction is not active.
*/
public ILocalBTreeView getIndex(final String name) {
if (name == null) throw new IllegalArgumentException();
if (readOnly) {
/*
* Note: Access to the indices currently goes through the
* IResourceManager interface for a read-only transaction.
*/
throw new UnsupportedOperationException();
}
/*
* @todo lock could be per index for higher concurrency rather than for
* all indices which you might access through this tx.
*/
lock.lock();
try {
if (!isActive()) {
throw new IllegalStateException(NOT_ACTIVE);
}
/*
* Test the cache - this is used so that we can recover the same
* instance on each call within the same transaction.
*/
if (indices.containsKey(name)) {
// Already defined.
return indices.get(name);
}
final ILocalBTreeView index;
/*
* See if the index was registered as of the ground state used by
* this transaction to isolated indices.
*
* Note: IResourceManager#getIndex(String name,long timestamp) calls
* us when the timestamp identifies an active transaction so we MUST
* NOT call that method ourselves! Hence there is some replication
* of logic between that method and this one.
*/
final AbstractBTree[] sources =
resourceManager.getIndexSources(name, readsOnCommitTime); // startTime);
if (sources == null) {
/*
* The named index was not registered as of the transaction
* ground state.
*/
if (log.isInfoEnabled()) log.info("No such index: " + name + ", startTime=" + startTime);
return null;
}
if (!sources[0].getIndexMetadata().isIsolatable()) {
throw new RuntimeException("Not isolatable: " + name);
}
/*
* Isolate the named btree.
*/
// if (readOnly) {
//
// assert sources[0].isReadOnly();
//
// if (sources.length == 1) {
//
// index = sources[0];
//
// } else {
//
// index = new FusedView(sources);
//
// }
//
// } else {
/*
* Setup the view. The write set is always the first element in
* the view.
*/
// the view definition.
final AbstractBTree[] b = new AbstractBTree[sources.length + 1];
/*
* Create the write set on a temporary store.
*
* Note: The BTree is NOT registered under a name so it can not
* be discovered on the temporary store. This is fine since we
* hold onto a hard reference to the BTree in [indices].
*/
b[0] = BTree.create(getTemporaryStore(), sources[0].getIndexMetadata().clone());
System.arraycopy(sources, 0, b, 1, sources.length);
// create view with isolated write set.
index = new IsolatedFusedView(-startTime, b);
// report event.
ResourceManager.isolateIndex(startTime, name);
// }
indices.put(name, index);
return index;
} finally {
lock.unlock();
}
}