package org.infinispan.persistence.file;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorCompletionService;
import org.infinispan.commons.equivalence.AnyEquivalence;
import org.infinispan.commons.equivalence.Equivalence;
import org.infinispan.commons.equivalence.EquivalentLinkedHashMap;
import org.infinispan.commons.io.ByteBufferFactory;
import org.infinispan.commons.util.CollectionFactory;
import org.infinispan.configuration.cache.SingleFileStoreConfiguration;
import org.infinispan.persistence.CacheLoaderException;
import org.infinispan.persistence.PersistenceUtil;
import org.infinispan.persistence.spi.AdvancedLoadWriteStore;
import org.infinispan.persistence.spi.InitializationContext;
import org.infinispan.marshall.core.MarshalledEntry;
import org.infinispan.marshall.core.MarshalledEntryImpl;
import org.infinispan.persistence.TaskContextImpl;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;
/**
* A filesystem-based implementation of a {@link org.infinispan.persistence.spi.CacheLoader}. This file store
* stores cache values in a single file <tt><location>/<cache name>.dat</tt>,
* keys and file positions are kept in memory.
* <p/>
* Note: this CacheStore implementation keeps keys and file positions in memory!
* The current implementation needs about 100 bytes per cache entry, plus the
* memory for the key objects.
* <p/>
* So, the space taken by this cache store is both the space in the file
* itself plus the in-memory index with the keys and their file positions.
* With this in mind and to avoid the cache store leading to
* OutOfMemoryExceptions, you can optionally configure the maximum number
* of entries to maintain in this cache store, which affects both the size
* of the file and the size of the in-memory index. However, setting this
* maximum limit results in older entries in the cache store to be eliminated,
* and hence, it only makes sense configuring a maximum limit if Infinispan
* is used as a cache where loss of data in the cache store does not lead to
* data loss, and data can be recomputed or re-queried from the original data
* source.
* <p/>
* This class is fully thread safe, yet allows for concurrent load / store
* of individual cache entries.
*
* @author Karsten Blees
* @author Mircea Markus
* @since 6.0
*/
public class SingleFileStore implements AdvancedLoadWriteStore {
private static final Log log = LogFactory.getLog(SingleFileStore.class);
private static final byte[] MAGIC = new byte[] { 'F', 'C', 'S', '1' };
private static final byte[] ZERO_INT = { 0, 0, 0, 0 };
private static final int KEYLEN_POS = 4;
private static final int KEY_POS = 4 + 4 + 4 + 4 + 8;
private SingleFileStoreConfiguration configuration;
protected InitializationContext ctx;
private FileChannel file;
private Map<Object, FileEntry> entries;
private SortedSet<FileEntry> freeList;
private long filePos = MAGIC.length;
/** {@inheritDoc} */
@Override
public void init(InitializationContext ctx) {
this.ctx = ctx;
this.configuration = ctx.getConfiguration();
}
/** {@inheritDoc} */
@Override
public void start() {
try {
// open the data file
String location = configuration.location();
if (location == null || location.trim().length() == 0)
location = "Infinispan-SingleFileStore";
File f = new File(location + File.separator + ctx.getCache().getName() + ".dat");
if (!f.exists()) {
File dir = f.getParentFile();
if (!dir.exists() && !dir.mkdirs()) {
throw log.directoryCannotBeCreated(dir.getAbsolutePath());
}
}
file = new RandomAccessFile(f, "rw").getChannel();
// initialize data structures
entries = newEntryMap();
freeList = Collections.synchronizedSortedSet(new TreeSet<FileEntry>());
// check file format and read persistent state if enabled for the cache
byte[] header = new byte[MAGIC.length];
if (file.read(ByteBuffer.wrap(header), 0) == MAGIC.length && Arrays.equals(MAGIC, header))
rebuildIndex();
else
clear(); // otherwise (unknown file format or no preload) just reset the file
} catch (Exception e) {
throw new CacheLoaderException(e);
}
}
private Map<Object, FileEntry> newEntryMap() {
// only use LinkedHashMap (LRU) for entries when cache store is bounded
final Map<Object, FileEntry> entryMap;
Equivalence<Object> keyEq = ctx.getCache().getCacheConfiguration().dataContainer().keyEquivalence();
if (configuration.maxEntries() > 0)
entryMap = CollectionFactory.makeLinkedMap(16, 0.75f,
EquivalentLinkedHashMap.IterationOrder.ACCESS_ORDER,
keyEq, AnyEquivalence.<FileEntry>getInstance());
else
entryMap = CollectionFactory.makeMap(keyEq, AnyEquivalence.<FileEntry>getInstance());
return Collections.synchronizedMap(entryMap);
}
/** {@inheritDoc} */
@Override
public void stop() {
try {
if (file != null) {
// reset state
file.close();
file = null;
entries = null;
freeList = null;
filePos = MAGIC.length;
}
} catch (Exception e) {
throw new CacheLoaderException(e);
}
}
/**
* Rebuilds the in-memory index from file.
*/
private void rebuildIndex() throws Exception {
ByteBuffer buf = ByteBuffer.allocate(KEY_POS);
for (;;) {
// read FileEntry fields from file (size, keyLen etc.)
buf.clear().limit(KEY_POS);
file.read(buf, filePos);
// return if end of file is reached
if (buf.remaining() > 0)
return;
buf.flip();
// initialize FileEntry from buffer
FileEntry fe = new FileEntry(filePos, buf.getInt());
fe.keyLen = buf.getInt();
fe.dataLen = buf.getInt();
fe.metadataLen = buf.getInt();
fe.expiryTime = buf.getLong();
// update file pointer
filePos += fe.size;
// check if the entry is used or free
if (fe.keyLen > 0) {
// load the key from file
if (buf.capacity() < fe.keyLen)
buf = ByteBuffer.allocate(fe.keyLen);
buf.clear().limit(fe.keyLen);
file.read(buf, fe.offset + KEY_POS);
// deserialize key and add to entries map
Object key = ctx.getMarshaller().objectFromByteBuffer(buf.array(), 0, fe.keyLen);
entries.put(key, fe);
} else {
// add to free list
freeList.add(fe);
}
}
}
/**
* {@inheritDoc}
* <p/>
* The base class implementation calls {@link #load(Object)} for this, we can do better because
* we keep all keys in memory.
*/
@Override
public boolean contains(Object key) {
return entries.containsKey(key);
}
/**
* Allocates the requested space in the file.
*
* @param len requested space
* @return allocated file position and length as FileEntry object
*/
private FileEntry allocate(int len) {
synchronized (freeList) {
// lookup a free entry of sufficient size
SortedSet<FileEntry> candidates = freeList.tailSet(new FileEntry(0, len));
for (Iterator<FileEntry> it = candidates.iterator(); it.hasNext();) {
FileEntry free = it.next();
// ignore entries that are still in use by concurrent readers
if (free.isLocked())
continue;
// There's no race condition risk between locking the entry on
// loading and checking whether it's locked (or store allocation),
// because for the entry to be lockable, it needs to be in the
// entries collection, in which case it's not in the free list.
// The only way an entry can be found in the free list is if it's
// been removed, and to remove it, lock on "entries" needs to be
// acquired, which is also a pre-requisite for loading data.
// found one, remove from freeList
it.remove();
return free;
}
// no appropriate free section available, append at end of file
FileEntry fe = new FileEntry(filePos, len);
filePos += len;
return fe;
}
}
/**
* Frees the space of the specified file entry (for reuse by allocate).
*/
private void free(FileEntry fe) throws IOException {
if (fe != null) {
// invalidate entry on disk (by setting keyLen field to 0)
file.write(ByteBuffer.wrap(ZERO_INT), fe.offset + KEYLEN_POS);
freeList.add(fe);
}
}
@Override
/** {@inheritDoc} */
public void write(MarshalledEntry marshalledEntry) {
try {
// serialize cache value
org.infinispan.commons.io.ByteBuffer key = marshalledEntry.getKeyBytes();
org.infinispan.commons.io.ByteBuffer data = marshalledEntry.getValueBytes();
org.infinispan.commons.io.ByteBuffer metadata = marshalledEntry.getMetadataBytes();
// allocate file entry and store in cache file
int metadataLength = metadata == null ? 0 : metadata.getLength();
int len = KEY_POS + key.getLength() + data.getLength() + metadataLength;
FileEntry fe = allocate(len);
try {
fe.expiryTime = metadata != null ? marshalledEntry.getMetadata().expiryTime() : -1;
fe.keyLen = key.getLength();
fe.dataLen = data.getLength();
fe.metadataLen = metadataLength;
ByteBuffer buf = ByteBuffer.allocate(len);
buf.putInt(fe.size);
buf.putInt(fe.keyLen);
buf.putInt(fe.dataLen);
buf.putInt(fe.metadataLen);
buf.putLong(fe.expiryTime);
buf.put(key.getBuf(), key.getOffset(), key.getLength());
buf.put(data.getBuf(), data.getOffset(), data.getLength());
if (metadata != null)
buf.put(metadata.getBuf(), metadata.getOffset(), metadata.getLength());
buf.flip();
file.write(buf, fe.offset);
// add the new entry to in-memory index
fe = entries.put(marshalledEntry.getKey(), fe);
// if we added an entry, check if we need to evict something
if (fe == null)
fe = evict();
} finally {
// in case we replaced or evicted an entry, add to freeList
free(fe);
}
} catch (Exception e) {
throw new CacheLoaderException(e);
}
}
/**
* Try to evict an entry if the capacity of the cache store is reached.
*
* @return FileEntry to evict, or null (if unbounded or capacity is not yet reached)
*/
private FileEntry evict() {
if (configuration.maxEntries() > 0) {
synchronized (entries) {
if (entries.size() > configuration.maxEntries()) {
Iterator<FileEntry> it = entries.values().iterator();
FileEntry fe = it.next();
it.remove();
return fe;
}
}
}
return null;
}
/** {@inheritDoc} */
@Override
public void clear() {
try {
synchronized (entries) {
synchronized (freeList) {
// wait until all readers are done reading file entries
for (FileEntry fe : entries.values())
fe.waitUnlocked();
for (FileEntry fe : freeList)
fe.waitUnlocked();
// clear in-memory state
entries.clear();
freeList.clear();
// reset file
file.truncate(0);
file.write(ByteBuffer.wrap(MAGIC), 0);
filePos = MAGIC.length;
}
}
} catch (Exception e) {
throw new CacheLoaderException(e);
}
}
/** {@inheritDoc} */
@Override
public boolean delete(Object key) {
try {
FileEntry fe = entries.remove(key);
free(fe);
return fe != null;
} catch (Exception e) {
throw new CacheLoaderException(e);
}
}
/** {@inheritDoc} */
@Override
public MarshalledEntry load(Object key) {
return _load(key, true, true);
}
private MarshalledEntry _load(Object key, boolean loadValue, boolean loadMetadata) {
final FileEntry fe;
final boolean expired;
synchronized (entries) {
// lookup FileEntry of the key
fe = entries.get(key);
if (fe == null)
return null;
// if expired, remove the entry (within entries monitor)
expired = fe.isExpired(System.currentTimeMillis());
if (expired)
entries.remove(key);
// lock entry for reading before releasing entries monitor
fe.lock();
}
final byte[] data;
try {
// if expired, free the file entry (after releasing entries monitor)
if (expired) {
free(fe);
return null;
}
// load serialized data from disk
data = new byte[fe.keyLen + (loadValue ? fe.dataLen : 0) + (loadMetadata ? fe.metadataLen : 0)];
file.read(ByteBuffer.wrap(data), fe.offset + KEY_POS);
} catch (Exception e) {
throw new CacheLoaderException(e);
} finally {
// no need to keep the lock for deserialization
fe.unlock();
}
ByteBufferFactory factory = ctx.getByteBufferFactory();
org.infinispan.commons.io.ByteBuffer keyBb = factory.newByteBuffer(data, 0, fe.keyLen);
org.infinispan.commons.io.ByteBuffer valueBb = null;
org.infinispan.commons.io.ByteBuffer metadataBb = null;
if (loadValue) {
valueBb = factory.newByteBuffer(data, fe.keyLen, fe.dataLen);
if (loadMetadata && fe.metadataLen > 0)
metadataBb = factory.newByteBuffer(data, fe.keyLen + fe.dataLen, fe.metadataLen);
}
return ctx.getMarshalledEntryFactory().newMarshalledEntry(keyBb, valueBb, metadataBb);
}
@Override
/** {@inheritDoc} */
public void process(KeyFilter filter, final CacheLoaderTask task, Executor executor, final boolean fetchValue, final boolean fetchMetadata) {
filter = PersistenceUtil.notNull(filter);
Set<Object> keysToLoad = new HashSet<Object>(entries.size());
synchronized (entries) {
for (Object k : entries.keySet()) {
if (filter.shouldLoadKey(k))
keysToLoad.add(k);
}
}
ExecutorCompletionService<Void> ecs = new ExecutorCompletionService<Void>(executor);
final TaskContextImpl taskContext = new TaskContextImpl();
int taskCount = 0;
for (Object k : keysToLoad) {
if (taskContext.isStopped())
break;
taskCount++;
final Object key = k;
ecs.submit(new Callable<Void>() {
@Override
public Void call() throws Exception {
final MarshalledEntry marshalledEntry = _load(key, fetchValue, fetchMetadata);
task.processEntry(marshalledEntry, taskContext);
return null;
}
});
}
PersistenceUtil.waitForAllTasksToComplete(ecs, taskCount);
}
@Override
/** {@inheritDoc} */
public void purge(Executor threadPool, final PurgeListener task) {
threadPool.execute(new Runnable() {
@Override
public void run() {
long now = System.currentTimeMillis();
synchronized (entries) {
for (Iterator<Map.Entry<Object, FileEntry>> it = entries.entrySet().iterator(); it.hasNext(); ) {
Map.Entry<Object, FileEntry> next = it.next();
FileEntry fe = next.getValue();
if (fe.isExpired(now)) {
it.remove();
try {
free(fe);
} catch (Exception e) {
throw new CacheLoaderException(e);
}
if (task != null) task.entryPurged(next.getKey());
}
}
}
}
});
}
@Override
public int size() {
return entries.size();
}
Map<Object, FileEntry> getEntries() {
return entries;
}
SortedSet<FileEntry> getFreeList() {
return freeList;
}
public SingleFileStoreConfiguration getConfiguration() {
return configuration;
}
/**
* Helper class to represent an entry in the cache file.
* <p/>
* The format of a FileEntry on disk is as follows:
* <ul>
* <li>4 bytes: {@link #size}</li>
* <li>4 bytes: {@link #keyLen}, 0 if the block is unused</li>
* <li>4 bytes: {@link #dataLen}</li>
* <li>4 bytes: {@link #metadataLen}</li>
* <li>8 bytes: {@link #expiryTime}</li>
* <li>{@link #keyLen} bytes: serialized key</li>
* <li>{@link #dataLen} bytes: serialized data</li>
* <li>{@link #metadataLen} bytes: serialized key</li>
* </ul>
*/
private static class FileEntry implements Comparable<Object> {
/**
* File offset of this block.
*/
private final long offset;
/**
* Total size of this block.
*/
private final int size;
/**
* Size of serialized key.
*/
private int keyLen;
/**
* Size of serialized data.
*/
private int dataLen;
/**
* Size of serialized metadata.
*/
private int metadataLen;
/**
* Time stamp when the entry will expire (i.e. will be collected by purge).
*/
private long expiryTime = -1;
/**
* Number of current readers.
*/
private transient int readers = 0;
private FileEntry(long offset, int size) {
this.offset = offset;
this.size = size;
}
private synchronized boolean isLocked() {
return readers > 0;
}
private synchronized void lock() {
readers++;
}
private synchronized void unlock() {
readers--;
if (readers == 0)
notifyAll();
}
private synchronized void waitUnlocked() {
while (readers > 0) {
try {
wait();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
private boolean isExpired(long now) {
return expiryTime > 0 && expiryTime < now;
}
/** {@inheritDoc} */
@Override
public int compareTo(Object o) {
FileEntry fe = (FileEntry) o;
if (this == fe)
return 0;
int diff = size - fe.size;
return (diff != 0) ? diff : offset > fe.offset ? 1 : -1;
}
}
}