package com.bigdata.journal;
import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.log4j.Logger;
import com.bigdata.counters.CounterSet;
import com.bigdata.counters.Instrument;
import com.bigdata.resources.StoreManager;
import com.bigdata.service.IBigdataFederation;
import com.bigdata.service.IDataService;
import com.bigdata.service.ITxState;
/**
* Manages the client side of a transaction either for a standalone
* {@link Journal} or for an {@link IDataService} in an
* {@link IBigdataFederation}.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
abstract public class AbstractLocalTransactionManager implements
ILocalTransactionManager {
/**
* Logger.
*/
private static final Logger log = Logger
.getLogger(AbstractLocalTransactionManager.class);
public AbstractLocalTransactionManager() {
}
/*
* ILocalTransactionManager
*/
/**
* A hash map containing all active transactions. A transaction that is
* preparing will remain in this collection until it has either successfully
* prepared or aborted.
*
* TODO Configure the initial capacity and concurrency. For example, this
* should be sized to the #of client connections for both the
* initialCapacity and the concurrency level.
*/
final private ConcurrentHashMap<Long, Tx> activeTx = new ConcurrentHashMap<Long, Tx>();
@Override
public ITxState[] getActiveTx() {
return activeTx.values().toArray(new ITxState[] {});
}
/**
* Notify the journal that a new transaction is being activated (starting on
* the journal).
*
* @param localState
* The transaction.
*
* @throws IllegalStateException
*/
public void activateTx(final Tx localState) throws IllegalStateException {
if (localState == null)
throw new IllegalArgumentException();
localState.lock.lock();
try {
if (activeTx
.putIfAbsent(localState.getStartTimestamp(), localState) != null) {
throw new IllegalStateException("Already in local table: tx="
+ localState);
}
} finally {
localState.lock.unlock();
}
}
/**
* Removes the transaction from the local tables.
*
* @param localState
* The transaction.
*/
protected void deactivateTx(final Tx localState)
throws IllegalStateException {
if (localState == null)
throw new IllegalArgumentException();
localState.lock.lock();
try {
if (!localState.isReadOnly() && !localState.isComplete())
throw new IllegalStateException("Not complete: "+localState);
// release any local resources.
localState.releaseResources();
if (activeTx.remove(localState.getStartTimestamp()) == null) {
throw new IllegalStateException("Not in local tables: tx="
+ localState);
}
} finally {
localState.lock.unlock();
}
}
/**
* Return the local state for a transaction.
*
* @param tx
* The transaction identifier.
*
* @return The local state for the identified transaction -or-
* <code>null</code> if the start time is not mapped to either an
* active or prepared transaction.
*/
public Tx getTx(final long tx) {
return activeTx.get(tx);
}
public boolean isOpen() {
return open;
}
private volatile boolean open = true;
synchronized public void shutdown() {
if(!open) return;
open = false;
}
synchronized public void shutdownNow() {
// Note: currently a NOP.
if(!open) return;
open = false;
}
/**
* Delay between attempts reach the remote service (ms).
*/
final long delay = 10L;
/**
* #of attempts to reach the remote service.
* <p>
* Note: delay*maxtries == 1000ms of trying before we give up, plus however
* long we are willing to wait for service discovery if the problem is
* locating the {@link ITransactionService}.
* <p>
* If this is not enough, then consider adding an optional parameter giving
* the time the caller will wait and letting the {@link StoreManager} wait
* longer during startup to discover the timestamp service.
*/
final int maxtries = 100;
/**
* Note: The reason for all this retry logic is to work around race
* conditions during service startup (and possibly during service failover)
* when the {@link ITimestampService} has not been discovered yet.
*/
public long nextTimestamp() {
final long begin = System.currentTimeMillis();
IOException cause = null;
int ntries;
for (ntries = 1; ntries <= maxtries; ntries++) {
try {
final ITransactionService transactionService = getTransactionService();
if (transactionService == null) {
log.warn("Service not discovered yet?");
try {
Thread.sleep(delay/* ms */);
continue;
} catch (InterruptedException e2) {
throw new RuntimeException(
"Interrupted awaiting timestamp service discovery: "
+ e2);
}
}
return transactionService.nextTimestamp();
} catch (IOException e) {
log.warn("Problem with timestamp service? : ntries=" + ntries
+ ", " + e, e);
cause = e;
}
}
final long elapsed = System.currentTimeMillis() - begin;
final String msg = "Could not get timestamp after " + ntries
+ " tries and " + elapsed + "ms";
log.error(msg, cause);
throw new RuntimeException(msg, cause);
}
public void notifyCommit(final long commitTime) {
final long begin = System.currentTimeMillis();
IOException cause = null;
int ntries;
for (ntries = 1; ntries <= maxtries; ntries++) {
try {
final ITransactionService transactionService = getTransactionService();
if (transactionService == null) {
log.warn("Service not discovered?");
try {
Thread.sleep(delay/* ms */);
} catch (InterruptedException e2) {
throw new RuntimeException(
"Interrupted awaiting timestamp service discovery: "
+ e2);
}
continue;
}
transactionService.notifyCommit(commitTime);
return;
} catch (IOException e) {
log.warn("Problem with timestamp service? : ntries=" + ntries
+ ", " + e, e);
cause = e;
}
}
final long elapsed = System.currentTimeMillis() - begin;
final String msg = "Could not notify timestamp service after " + ntries
+ " tries and " + elapsed + "ms";
log.error(msg, cause);
throw new RuntimeException(msg, cause);
}
/**
* Return interesting statistics about the transaction manager.
*/
public CounterSet getCounters() {
final CounterSet countersRoot = new CounterSet();
countersRoot.addCounter("#active", new Instrument<Integer>() {
protected void sample() {
setValue(activeTx.size());
}
});
return countersRoot;
}
}