/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.db;
import java.io.File;
import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicReference;
import com.google.common.collect.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.compaction.OperationType;
import org.apache.cassandra.io.sstable.SSTableReader;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.metrics.StorageMetrics;
import org.apache.cassandra.notifications.INotification;
import org.apache.cassandra.notifications.INotificationConsumer;
import org.apache.cassandra.notifications.SSTableAddedNotification;
import org.apache.cassandra.notifications.SSTableDeletingNotification;
import org.apache.cassandra.notifications.SSTableListChangedNotification;
import org.apache.cassandra.utils.Interval;
import org.apache.cassandra.utils.IntervalTree;
public class DataTracker
{
private static final Logger logger = LoggerFactory.getLogger(DataTracker.class);
public final Collection<INotificationConsumer> subscribers = new CopyOnWriteArrayList<INotificationConsumer>();
public final ColumnFamilyStore cfstore;
private final AtomicReference<View> view;
public DataTracker(ColumnFamilyStore cfstore)
{
this.cfstore = cfstore;
this.view = new AtomicReference<View>();
this.init();
}
public Memtable getMemtable()
{
return view.get().memtable;
}
public Set<Memtable> getMemtablesPendingFlush()
{
return view.get().memtablesPendingFlush;
}
public Set<SSTableReader> getSSTables()
{
return view.get().sstables;
}
public Set<SSTableReader> getUncompactingSSTables()
{
return view.get().nonCompactingSStables();
}
public View getView()
{
return view.get();
}
/**
* Switch the current memtable.
* This atomically adds the current memtable to the memtables pending
* flush and replace it with a fresh memtable.
*
* @return the previous current memtable (the one added to the pending
* flush)
*/
public Memtable switchMemtable()
{
// atomically change the current memtable
Memtable newMemtable = new Memtable(cfstore);
Memtable toFlushMemtable;
View currentView, newView;
do
{
currentView = view.get();
toFlushMemtable = currentView.memtable;
newView = currentView.switchMemtable(newMemtable);
}
while (!view.compareAndSet(currentView, newView));
return toFlushMemtable;
}
/**
* Renew the current memtable without putting the old one for a flush.
* Used when we flush but a memtable is clean (in which case we must
* change it because it was frozen).
*/
public void renewMemtable()
{
Memtable newMemtable = new Memtable(cfstore);
View currentView, newView;
do
{
currentView = view.get();
newView = currentView.renewMemtable(newMemtable);
}
while (!view.compareAndSet(currentView, newView));
}
public void replaceFlushed(Memtable memtable, SSTableReader sstable)
{
// sstable may be null if we flushed batchlog and nothing needed to be retained
if (!cfstore.isValid())
{
View currentView, newView;
do
{
currentView = view.get();
newView = currentView.replaceFlushed(memtable, sstable);
if (sstable != null)
newView = newView.replace(Arrays.asList(sstable), Collections.<SSTableReader>emptyList());
}
while (!view.compareAndSet(currentView, newView));
return;
}
// back up before creating a new View (which makes the new one eligible for compaction)
if (sstable != null)
maybeIncrementallyBackup(sstable);
View currentView, newView;
do
{
currentView = view.get();
newView = currentView.replaceFlushed(memtable, sstable);
}
while (!view.compareAndSet(currentView, newView));
if (sstable != null)
{
addNewSSTablesSize(Arrays.asList(sstable));
notifyAdded(sstable);
}
}
public void maybeIncrementallyBackup(final SSTableReader sstable)
{
if (!DatabaseDescriptor.isIncrementalBackupsEnabled())
return;
File backupsDir = Directories.getBackupsDirectory(sstable.descriptor);
sstable.createLinks(FileUtils.getCanonicalPath(backupsDir));
}
/**
* @return true if we are able to mark the given @param sstables as compacted, before anyone else
*
* Note that we could acquire references on the marked sstables and release them in
* unmarkCompacting, but since we will never call markCompacted on a sstable marked
* as compacting (unless there is a serious bug), we can skip this.
*/
public boolean markCompacting(Collection<SSTableReader> sstables)
{
assert sstables != null && !sstables.isEmpty();
View currentView = view.get();
Set<SSTableReader> inactive = Sets.difference(ImmutableSet.copyOf(sstables), currentView.compacting);
if (inactive.size() < sstables.size())
return false;
View newView = currentView.markCompacting(inactive);
return view.compareAndSet(currentView, newView);
}
/**
* Removes files from compacting status: this is different from 'markCompacted'
* because it should be run regardless of whether a compaction succeeded.
*/
public void unmarkCompacting(Collection<SSTableReader> unmark)
{
if (!cfstore.isValid())
{
// We don't know if the original compaction suceeded or failed, which makes it difficult to know
// if the sstable reference has already been released.
// A "good enough" approach is to mark the sstables involved compacted, which if compaction succeeded
// is harmlessly redundant, and if it failed ensures that at least the sstable will get deleted on restart.
for (SSTableReader sstable : unmark)
sstable.markCompacted();
}
View currentView, newView;
do
{
currentView = view.get();
newView = currentView.unmarkCompacting(unmark);
}
while (!view.compareAndSet(currentView, newView));
}
public void markCompacted(Collection<SSTableReader> sstables, OperationType compactionType)
{
replace(sstables, Collections.<SSTableReader>emptyList());
notifySSTablesChanged(sstables, Collections.<SSTableReader>emptyList(), compactionType);
}
public void replaceCompactedSSTables(Collection<SSTableReader> sstables, Iterable<SSTableReader> replacements, OperationType compactionType)
{
replace(sstables, replacements);
notifySSTablesChanged(sstables, replacements, compactionType);
}
public void addInitialSSTables(Collection<SSTableReader> sstables)
{
replace(Collections.<SSTableReader>emptyList(), sstables);
// no notifications or backup necessary
}
public void addSSTables(Collection<SSTableReader> sstables)
{
replace(Collections.<SSTableReader>emptyList(), sstables);
for (SSTableReader sstable : sstables)
{
maybeIncrementallyBackup(sstable);
notifyAdded(sstable);
}
}
/**
* removes all sstables that are not busy compacting.
*/
public void unreferenceSSTables()
{
Set<SSTableReader> notCompacting;
View currentView, newView;
do
{
currentView = view.get();
notCompacting = currentView.nonCompactingSStables();
newView = currentView.replace(notCompacting, Collections.<SSTableReader>emptySet());
}
while (!view.compareAndSet(currentView, newView));
if (notCompacting.isEmpty())
{
// notifySSTablesChanged -> LeveledManifest.promote doesn't like a no-op "promotion"
return;
}
notifySSTablesChanged(notCompacting, Collections.<SSTableReader>emptySet(), OperationType.UNKNOWN);
postReplace(notCompacting, Collections.<SSTableReader>emptySet());
}
/**
* Removes every SSTable in the directory from the DataTracker's view.
* @param directory the unreadable directory, possibly with SSTables in it, but not necessarily.
*/
void removeUnreadableSSTables(File directory)
{
View currentView, newView;
List<SSTableReader> remaining = new ArrayList<SSTableReader>();
do
{
currentView = view.get();
for (SSTableReader r : currentView.nonCompactingSStables())
{
if (!r.descriptor.directory.equals(directory))
remaining.add(r);
}
if (remaining.size() == currentView.nonCompactingSStables().size())
return;
newView = currentView.replace(currentView.sstables, remaining);
}
while (!view.compareAndSet(currentView, newView));
notifySSTablesChanged(remaining, Collections.<SSTableReader>emptySet(), OperationType.UNKNOWN);
}
/** (Re)initializes the tracker, purging all references. */
void init()
{
view.set(new View(new Memtable(cfstore),
Collections.<Memtable>emptySet(),
Collections.<SSTableReader>emptySet(),
Collections.<SSTableReader>emptySet(),
SSTableIntervalTree.empty()));
}
private void replace(Collection<SSTableReader> oldSSTables, Iterable<SSTableReader> replacements)
{
if (!cfstore.isValid())
{
removeOldSSTablesSize(replacements);
replacements = Collections.emptyList();
}
View currentView, newView;
do
{
currentView = view.get();
newView = currentView.replace(oldSSTables, replacements);
}
while (!view.compareAndSet(currentView, newView));
postReplace(oldSSTables, replacements);
}
private void postReplace(Collection<SSTableReader> oldSSTables, Iterable<SSTableReader> replacements)
{
addNewSSTablesSize(replacements);
removeOldSSTablesSize(oldSSTables);
}
private void addNewSSTablesSize(Iterable<SSTableReader> newSSTables)
{
for (SSTableReader sstable : newSSTables)
{
if (logger.isDebugEnabled())
logger.debug(String.format("adding %s to list of files tracked for %s.%s",
sstable.descriptor, cfstore.table.name, cfstore.getColumnFamilyName()));
long size = sstable.bytesOnDisk();
StorageMetrics.load.inc(size);
cfstore.metric.liveDiskSpaceUsed.inc(size);
cfstore.metric.totalDiskSpaceUsed.inc(size);
sstable.setTrackedBy(this);
}
}
private void removeOldSSTablesSize(Iterable<SSTableReader> oldSSTables)
{
for (SSTableReader sstable : oldSSTables)
{
if (logger.isDebugEnabled())
logger.debug(String.format("removing %s from list of files tracked for %s.%s",
sstable.descriptor, cfstore.table.name, cfstore.getColumnFamilyName()));
long size = sstable.bytesOnDisk();
StorageMetrics.load.dec(size);
cfstore.metric.liveDiskSpaceUsed.dec(size);
boolean firstToCompact = sstable.markCompacted();
assert firstToCompact : sstable + " was already marked compacted";
sstable.releaseReference();
}
}
public void spaceReclaimed(long size)
{
cfstore.metric.totalDiskSpaceUsed.dec(size);
}
public long estimatedKeys()
{
long n = 0;
for (SSTableReader sstable : getSSTables())
{
n += sstable.estimatedKeys();
}
return n;
}
public int getMeanColumns()
{
long sum = 0;
int count = 0;
for (SSTableReader sstable : getSSTables())
{
sum += sstable.getEstimatedColumnCount().mean();
count++;
}
return count > 0 ? (int) (sum / count) : 0;
}
public double getDroppableTombstoneRatio()
{
double allDroppable = 0;
long allColumns = 0;
int localTime = (int)(System.currentTimeMillis()/1000);
for (SSTableReader sstable : getSSTables())
{
allDroppable += sstable.getDroppableTombstonesBefore(localTime - sstable.metadata.getGcGraceSeconds());
allColumns += sstable.getEstimatedColumnCount().mean() * sstable.getEstimatedColumnCount().count();
}
if (allColumns > 0)
{
return allDroppable / allColumns;
}
return 0;
}
public void notifySSTablesChanged(Iterable<SSTableReader> removed, Iterable<SSTableReader> added, OperationType compactionType)
{
for (INotificationConsumer subscriber : subscribers)
{
INotification notification = new SSTableListChangedNotification(added, removed, compactionType);
subscriber.handleNotification(notification, this);
}
}
public void notifyAdded(SSTableReader added)
{
INotification notification = new SSTableAddedNotification(added);
for (INotificationConsumer subscriber : subscribers)
subscriber.handleNotification(notification, this);
}
public void notifyDeleting(SSTableReader deleting)
{
INotification notification = new SSTableDeletingNotification(deleting);
for (INotificationConsumer subscriber : subscribers)
subscriber.handleNotification(notification, this);
}
public void subscribe(INotificationConsumer consumer)
{
subscribers.add(consumer);
}
public void unsubscribe(INotificationConsumer consumer)
{
boolean found = subscribers.remove(consumer);
assert found : consumer + " not subscribed";
}
public static SSTableIntervalTree buildIntervalTree(Iterable<SSTableReader> sstables)
{
List<Interval<RowPosition, SSTableReader>> intervals = new ArrayList<Interval<RowPosition, SSTableReader>>(Iterables.size(sstables));
for (SSTableReader sstable : sstables)
intervals.add(Interval.<RowPosition, SSTableReader>create(sstable.first, sstable.last, sstable));
return new SSTableIntervalTree(intervals);
}
public Set<SSTableReader> getCompacting()
{
return getView().compacting;
}
public static class SSTableIntervalTree extends IntervalTree<RowPosition, SSTableReader, Interval<RowPosition, SSTableReader>>
{
private static final SSTableIntervalTree EMPTY = new SSTableIntervalTree(null);
private SSTableIntervalTree(Collection<Interval<RowPosition, SSTableReader>> intervals)
{
super(intervals, null);
}
public static SSTableIntervalTree empty()
{
return EMPTY;
}
}
/**
* An immutable structure holding the current memtable, the memtables pending
* flush, the sstables for a column family, and the sstables that are active
* in compaction (a subset of the sstables).
*/
static class View
{
public final Memtable memtable;
public final Set<Memtable> memtablesPendingFlush;
public final Set<SSTableReader> compacting;
public final Set<SSTableReader> sstables;
public final SSTableIntervalTree intervalTree;
View(Memtable memtable, Set<Memtable> pendingFlush, Set<SSTableReader> sstables, Set<SSTableReader> compacting, SSTableIntervalTree intervalTree)
{
this.memtable = memtable;
this.memtablesPendingFlush = pendingFlush;
this.sstables = sstables;
this.compacting = compacting;
this.intervalTree = intervalTree;
}
public Sets.SetView<SSTableReader> nonCompactingSStables()
{
return Sets.difference(ImmutableSet.copyOf(sstables), compacting);
}
public View switchMemtable(Memtable newMemtable)
{
Set<Memtable> newPending = ImmutableSet.<Memtable>builder().addAll(memtablesPendingFlush).add(memtable).build();
return new View(newMemtable, newPending, sstables, compacting, intervalTree);
}
public View renewMemtable(Memtable newMemtable)
{
return new View(newMemtable, memtablesPendingFlush, sstables, compacting, intervalTree);
}
public View replaceFlushed(Memtable flushedMemtable, SSTableReader newSSTable)
{
Set<Memtable> newPending = ImmutableSet.copyOf(Sets.difference(memtablesPendingFlush, Collections.singleton(flushedMemtable)));
Set<SSTableReader> newSSTables = newSSTable == null
? sstables
: newSSTables(newSSTable);
SSTableIntervalTree intervalTree = buildIntervalTree(newSSTables);
return new View(memtable, newPending, newSSTables, compacting, intervalTree);
}
public View replace(Collection<SSTableReader> oldSSTables, Iterable<SSTableReader> replacements)
{
Set<SSTableReader> newSSTables = newSSTables(oldSSTables, replacements);
SSTableIntervalTree intervalTree = buildIntervalTree(newSSTables);
return new View(memtable, memtablesPendingFlush, newSSTables, compacting, intervalTree);
}
public View markCompacting(Collection<SSTableReader> tomark)
{
Set<SSTableReader> compactingNew = ImmutableSet.<SSTableReader>builder().addAll(compacting).addAll(tomark).build();
return new View(memtable, memtablesPendingFlush, sstables, compactingNew, intervalTree);
}
public View unmarkCompacting(Collection<SSTableReader> tounmark)
{
Set<SSTableReader> compactingNew = ImmutableSet.copyOf(Sets.difference(compacting, ImmutableSet.copyOf(tounmark)));
return new View(memtable, memtablesPendingFlush, sstables, compactingNew, intervalTree);
}
private Set<SSTableReader> newSSTables(SSTableReader newSSTable)
{
assert newSSTable != null;
// not performance-sensitive, don't obsess over doing a selection merge here
return newSSTables(Collections.<SSTableReader>emptyList(), Collections.singletonList(newSSTable));
}
private Set<SSTableReader> newSSTables(Collection<SSTableReader> oldSSTables, Iterable<SSTableReader> replacements)
{
ImmutableSet<SSTableReader> oldSet = ImmutableSet.copyOf(oldSSTables);
int newSSTablesSize = sstables.size() - oldSSTables.size() + Iterables.size(replacements);
assert newSSTablesSize >= Iterables.size(replacements) : String.format("Incoherent new size %d replacing %s by %s in %s", newSSTablesSize, oldSSTables, replacements, this);
Set<SSTableReader> newSSTables = new HashSet<SSTableReader>(newSSTablesSize);
for (SSTableReader sstable : sstables)
{
if (!oldSet.contains(sstable))
newSSTables.add(sstable);
}
Iterables.addAll(newSSTables, replacements);
assert newSSTables.size() == newSSTablesSize : String.format("Expecting new size of %d, got %d while replacing %s by %s in %s", newSSTablesSize, newSSTables.size(), oldSSTables, replacements, this);
return ImmutableSet.copyOf(newSSTables);
}
@Override
public String toString()
{
return String.format("View(pending_count=%d, sstables=%s, compacting=%s)", memtablesPendingFlush.size(), sstables, compacting);
}
}
}