Files
briar/components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java

499 lines
13 KiB
Java

package net.sf.briar.db;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.sf.briar.api.db.DbException;
import net.sf.briar.api.db.NeighbourId;
import net.sf.briar.api.db.Rating;
import net.sf.briar.api.protocol.AuthorId;
import net.sf.briar.api.protocol.Batch;
import net.sf.briar.api.protocol.BatchId;
import net.sf.briar.api.protocol.Bundle;
import net.sf.briar.api.protocol.GroupId;
import net.sf.briar.api.protocol.Message;
import net.sf.briar.api.protocol.MessageId;
import com.google.inject.Inject;
import com.google.inject.Provider;
class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
private static final Logger LOG =
Logger.getLogger(ReadWriteLockDatabaseComponent.class.getName());
/*
* Locks must always be acquired in alphabetical order. See the Database
* interface to find out which calls require which locks. Note: this
* implementation can allow writers to starve.
*/
private final ReentrantReadWriteLock messageLock =
new ReentrantReadWriteLock(true);
private final ReentrantReadWriteLock neighbourLock =
new ReentrantReadWriteLock(true);
private final ReentrantReadWriteLock ratingLock =
new ReentrantReadWriteLock(true);
private final ReentrantReadWriteLock subscriptionLock =
new ReentrantReadWriteLock(true);
@Inject
ReadWriteLockDatabaseComponent(Database<Txn> db,
Provider<Batch> batchProvider) {
super(db, batchProvider);
}
protected void expireMessages(long size) throws DbException {
messageLock.writeLock().lock();
try {
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
for(MessageId m : db.getOldMessages(txn, size)) {
removeMessage(txn, m);
}
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
public void close() throws DbException {
messageLock.writeLock().lock();
try {
neighbourLock.writeLock().lock();
try {
ratingLock.writeLock().lock();
try {
subscriptionLock.writeLock().lock();
try {
db.close();
} finally {
subscriptionLock.writeLock().unlock();
}
} finally {
ratingLock.writeLock().unlock();
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
public void addNeighbour(NeighbourId n) throws DbException {
if(LOG.isLoggable(Level.FINE)) LOG.fine("Adding neighbour " + n);
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
db.addNeighbour(txn, n);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
}
public void addLocallyGeneratedMessage(Message m) throws DbException {
waitForPermissionToWrite();
messageLock.writeLock().lock();
try {
neighbourLock.writeLock().lock();
try {
subscriptionLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
if(db.containsSubscription(txn, m.getGroup())) {
boolean added = storeMessage(txn, m, null);
assert added;
} else {
if(LOG.isLoggable(Level.FINE))
LOG.fine("Not subscribed");
}
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.readLock().unlock();
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
public Rating getRating(AuthorId a) throws DbException {
ratingLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
Rating r = db.getRating(txn, a);
db.commitTransaction(txn);
return r;
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
ratingLock.readLock().unlock();
}
}
public void setRating(AuthorId a, Rating r) throws DbException {
messageLock.writeLock().lock();
try {
ratingLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
Rating old = db.setRating(txn, a, r);
// Update the sendability of the author's messages
if(r == Rating.GOOD && old != Rating.GOOD)
updateAuthorSendability(txn, a, true);
else if(r != Rating.GOOD && old == Rating.GOOD)
updateAuthorSendability(txn, a, false);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
ratingLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
public Set<GroupId> getSubscriptions() throws DbException {
subscriptionLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
HashSet<GroupId> subs = new HashSet<GroupId>();
for(GroupId g : db.getSubscriptions(txn)) subs.add(g);
db.commitTransaction(txn);
return subs;
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.readLock().unlock();
}
}
public void subscribe(GroupId g) throws DbException {
if(LOG.isLoggable(Level.FINE)) LOG.fine("Subscribing to " + g);
subscriptionLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
db.addSubscription(txn, g);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.writeLock().unlock();
}
}
public void unsubscribe(GroupId g) throws DbException {
if(LOG.isLoggable(Level.FINE)) LOG.fine("Unsubscribing from " + g);
messageLock.writeLock().lock();
try {
neighbourLock.writeLock().lock();
try {
subscriptionLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
db.removeSubscription(txn, g);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.writeLock().unlock();
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
public void generateBundle(NeighbourId n, Bundle b) throws DbException {
if(LOG.isLoggable(Level.FINE)) LOG.fine("Generating bundle for " + n);
// Ack all batches received from the neighbour
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
int numAcks = 0;
for(BatchId ack : db.removeBatchesToAck(txn, n)) {
b.addAck(ack);
numAcks++;
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Added " + numAcks + " acks");
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
// Add a list of subscriptions
subscriptionLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
int numSubs = 0;
for(GroupId g : db.getSubscriptions(txn)) {
b.addSubscription(g);
numSubs++;
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Added " + numSubs + " subscriptions");
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.readLock().unlock();
}
// Add as many messages as possible to the bundle
long capacity = b.getCapacity();
while(true) {
Batch batch = fillBatch(n, capacity);
if(batch == null) break; // No more messages to send
b.addBatch(batch);
capacity -= batch.getSize();
// If the batch is less than half full, stop trying - there may be
// more messages trickling in but we can't wait forever
if(batch.getSize() * 2 < Batch.CAPACITY) break;
}
b.seal();
if(LOG.isLoggable(Level.FINE))
LOG.fine("Bundle sent, " + b.getSize() + " bytes");
System.gc();
}
private Batch fillBatch(NeighbourId n, long capacity) throws DbException {
messageLock.readLock().lock();
try {
Set<MessageId> sent;
Batch b;
neighbourLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
capacity = Math.min(capacity, Batch.CAPACITY);
Iterator<MessageId> it =
db.getSendableMessages(txn, n, capacity).iterator();
if(!it.hasNext()) {
db.commitTransaction(txn);
return null; // No more messages to send
}
sent = new HashSet<MessageId>();
b = batchProvider.get();
while(it.hasNext()) {
MessageId m = it.next();
b.addMessage(db.getMessage(txn, m));
sent.add(m);
}
b.seal();
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.readLock().unlock();
}
// Record the contents of the batch
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
assert !sent.isEmpty();
db.addOutstandingBatch(txn, n, b.getId(), sent);
db.commitTransaction(txn);
return b;
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.readLock().unlock();
}
}
public void receiveBundle(NeighbourId n, Bundle b) throws DbException {
if(LOG.isLoggable(Level.FINE))
LOG.fine("Received bundle from " + n + ", "
+ b.getSize() + " bytes");
// Mark all messages in acked batches as seen
messageLock.readLock().lock();
try {
neighbourLock.writeLock().lock();
try {
int acks = 0;
for(BatchId ack : b.getAcks()) {
acks++;
Txn txn = db.startTransaction();
try {
db.removeAckedBatch(txn, n, ack);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Received " + acks + " acks");
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.readLock().unlock();
}
// Update the neighbour's subscriptions
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
db.clearSubscriptions(txn, n);
int subs = 0;
for(GroupId g : b.getSubscriptions()) {
subs++;
db.addSubscription(txn, n, g);
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Received " + subs + " subscriptions");
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
// Store the messages
int batches = 0;
for(Batch batch : b.getBatches()) {
batches++;
waitForPermissionToWrite();
messageLock.writeLock().lock();
try {
neighbourLock.writeLock().lock();
try {
subscriptionLock.readLock().lock();
try {
Txn txn = db.startTransaction();
try {
int received = 0, stored = 0;
for(Message m : batch.getMessages()) {
received++;
if(db.containsSubscription(txn, m.getGroup())) {
if(storeMessage(txn, m, n)) stored++;
}
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Received " + received
+ " messages, stored " + stored);
db.addBatchToAck(txn, n, batch.getId());
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
subscriptionLock.readLock().unlock();
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.writeLock().unlock();
}
}
if(LOG.isLoggable(Level.FINE))
LOG.fine("Received " + batches + " batches");
// Find any lost batches that need to be retransmitted
Set<BatchId> lost;
messageLock.readLock().lock();
try {
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
lost = db.addReceivedBundle(txn, n, b.getId());
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.readLock().unlock();
}
for(BatchId batch : lost) {
messageLock.readLock().lock();
try {
neighbourLock.writeLock().lock();
try {
Txn txn = db.startTransaction();
try {
if(LOG.isLoggable(Level.FINE))
LOG.fine("Removing lost batch");
db.removeLostBatch(txn, n, batch);
db.commitTransaction(txn);
} catch(DbException e) {
db.abortTransaction(txn);
throw e;
}
} finally {
neighbourLock.writeLock().unlock();
}
} finally {
messageLock.readLock().unlock();
}
}
System.gc();
}
}