package org.terracotta.offheapstore.disk.storage;
import java.io.EOFException;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Lock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.terracotta.offheapstore.disk.paging.MappedPageSource;
import org.terracotta.offheapstore.disk.persistent.Persistent;
import org.terracotta.offheapstore.disk.persistent.PersistentStorageEngine;
import org.terracotta.offheapstore.storage.PortabilityBasedStorageEngine;
import org.terracotta.offheapstore.storage.portability.Portability;
import org.terracotta.offheapstore.storage.portability.WriteContext;
import org.terracotta.offheapstore.util.Factory;
import org.terracotta.offheapstore.util.MemoryUnit;
import static java.lang.Long.highestOneBit;
import static java.lang.Math.max;
import static java.lang.Math.min;
public class FileBackedStorageEngine<K, V> extends PortabilityBasedStorageEngine<K, V> implements PersistentStorageEngine<K, V> {
private static final int MAGIC = 0x414d4445;
private static final int MAGIC_CHUNK = 0x4e4e4953;
private static final Logger LOGGER = LoggerFactory.getLogger(FileBackedStorageEngine.class);
private static final int KEY_HASH_OFFSET = 0;
private static final int KEY_LENGTH_OFFSET = 4;
private static final int VALUE_LENGTH_OFFSET = 8;
private static final int KEY_DATA_OFFSET = 12;
private final ConcurrentHashMap<Long, FileWriteTask> pendingWrites = new ConcurrentHashMap<>();
private final ExecutorService writeExecutor;
private final MappedPageSource source;
private final FileChannel writeChannel;
private final AtomicReference<FileChannel> readChannelReference;
private final TreeMap<Long, FileChunk> chunks = new TreeMap<>();
private final long maxChunkSize;
private volatile Owner owner;
public static <K, V> Factory<FileBackedStorageEngine<K, V>> createFactory(final MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, final Portability<? super K> keyPortability, final Portability<? super V> valuePortability) {
return createFactory(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, true);
}
public static <K, V> Factory<FileBackedStorageEngine<K, V>> createFactory(final MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, final Portability<? super K> keyPortability, final Portability<? super V> valuePortability, final boolean bootstrap) {
Factory<ExecutorService> executorFactory = () -> new ThreadPoolExecutor(1, 1, 0, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>());
return createFactory(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, executorFactory, bootstrap);
}
public static <K, V> Factory<FileBackedStorageEngine<K, V>> createFactory(final MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, final Portability<? super K> keyPortability, final Portability<? super V> valuePortability, final Factory<ExecutorService> executorFactory, final boolean bootstrap) {
return () -> new FileBackedStorageEngine<>(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, executorFactory
.newInstance(), bootstrap);
}
public FileBackedStorageEngine(MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, Portability<? super K> keyPortability, Portability<? super V> valuePortability) {
this(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, true);
}
public FileBackedStorageEngine(MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, Portability<? super K> keyPortability, Portability<? super V> valuePortability, ExecutorService writer) {
this(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, writer, true);
}
public FileBackedStorageEngine(MappedPageSource source, final long maxChunkSize, final MemoryUnit maxChunkUnit, Portability<? super K> keyPortability, Portability<? super V> valuePortability, boolean bootstrap) {
this(source, maxChunkSize, maxChunkUnit, keyPortability, valuePortability, new ThreadPoolExecutor(1, 1, 0, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>()), bootstrap);
}
public FileBackedStorageEngine(MappedPageSource source, long maxChunkSize, MemoryUnit maxChunkUnit, Portability<? super K> keyPortability, Portability<? super V> valuePortability, ExecutorService writer, boolean bootstrap) {
super(keyPortability, valuePortability);
this.writeExecutor = writer;
this.writeChannel = source.getWritableChannel();
this.readChannelReference = new AtomicReference<>(source.getReadableChannel());
this.source = source;
this.maxChunkSize = highestOneBit(maxChunkUnit.toBytes(maxChunkSize));
}
@Override
protected void clearInternal() {
Iterator<Entry<Long, FileChunk>> it = chunks.entrySet().iterator();
while (it.hasNext()) {
it.next().getValue().clear();
it.remove();
}
if (!chunks.isEmpty()) {
throw new AssertionError("Concurrent modification while clearing!");
}
}
@Override
public void destroy() {
try {
close();
} catch (IOException e) {
LOGGER.warn("Exception while trying to close file backed storage engine", e);
}
}
@Override
public void flush() throws IOException {
Future<Void> flush = writeExecutor.submit(() -> {
writeChannel.force(true);
return null;
});
boolean interrupted = Thread.interrupted();
try {
while (true) {
try {
flush.get();
break;
} catch (InterruptedException ex) {
interrupted = true;
} catch (ExecutionException ex) {
Throwable cause = ex.getCause();
if (cause instanceof RuntimeException) {
throw (RuntimeException) cause;
} else if (cause instanceof IOException) {
throw (IOException) cause;
} else {
throw new RuntimeException(cause);
}
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
@Override
public void close() throws IOException {
try {
writeExecutor.shutdownNow();
if (writeExecutor.awaitTermination(60, TimeUnit.SECONDS)) {
LOGGER.debug("FileBackedStorageEngine for " + source.getFile().getName() + " terminated successfully");
} else {
LOGGER.warn("FileBackedStorageEngine for " + source.getFile().getName() + " timed-out during termination");
}
} catch (InterruptedException e) {
LOGGER.warn("FileBackedStorageEngine for " + source.getFile().getName() + " interrupted during termination");
Thread.currentThread().interrupt();
} finally {
try {
writeChannel.close();
} finally {
readChannelReference.getAndSet(null).close();
}
}
}
@Override
public void persist(ObjectOutput output) throws IOException {
output.writeInt(MAGIC);
((Persistent) keyPortability).persist(output);
((Persistent) valuePortability).persist(output);
output.writeInt(chunks.size());
for (FileChunk c : chunks.values()) {
c.persist(output);
}
}
@Override
public void bootstrap(ObjectInput input) throws IOException {
if (!chunks.isEmpty()) {
throw new IllegalStateException();
}
if (input.readInt() != MAGIC) {
throw new IOException("Wrong magic number");
}
((Persistent) keyPortability).bootstrap(input);
((Persistent) valuePortability).bootstrap(input);
int n = input.readInt();
for (int i = 0; i < n; i++) {
FileChunk chunk = new FileChunk(input);
chunks.put(chunk.baseAddress(), chunk);
}
if (hasRecoveryListeners()) {
for (Long encoding : owner.encodingSet()) {
ByteBuffer binaryKey = readBinaryKey(encoding);
ByteBuffer binaryValue = readBinaryValue(encoding);
int hash = readKeyHash(encoding);
final ByteBuffer binaryKeyForDecode = binaryKey.duplicate();
final ByteBuffer binaryValueForDecode = binaryValue.duplicate();
final Thread caller = Thread.currentThread();
fireRecovered(() -> {
if (caller == Thread.currentThread()) {
@SuppressWarnings("unchecked")
K result = (K) keyPortability.decode(binaryKeyForDecode.duplicate());
return result;
} else {
throw new IllegalStateException();
}
}, () -> {
if (caller == Thread.currentThread()) {
@SuppressWarnings("unchecked")
V result = (V) valuePortability.decode(binaryValueForDecode.duplicate());
return result;
} else {
throw new IllegalStateException();
}
}, binaryKey, binaryValue, hash, 0, encoding);
}
}
}
@Override
protected void free(long address) {
FileChunk chunk = findChunk(address);
chunk.free(address - chunk.baseAddress());
}
@Override
protected ByteBuffer readKeyBuffer(long address) {
FileChunk chunk = findChunk(address);
return chunk.readKeyBuffer(address - chunk.baseAddress());
}
@Override
protected WriteContext getKeyWriteContext(long address) {
FileChunk chunk = findChunk(address);
return chunk.getKeyWriteContext(address - chunk.baseAddress());
}
@Override
protected ByteBuffer readValueBuffer(long address) {
FileChunk chunk = findChunk(address);
return chunk.readValueBuffer(address - chunk.baseAddress());
}
@Override
protected WriteContext getValueWriteContext(long address) {
FileChunk chunk = findChunk(address);
return chunk.getValueWriteContext(address - chunk.baseAddress());
}
@Override
protected Long writeMappingBuffers(ByteBuffer keyBuffer, ByteBuffer valueBuffer, int hash) {
for (FileChunk c : chunks.values()) {
Long address = c.writeMappingBuffers(keyBuffer, valueBuffer, hash);
if (address != null) {
return address + c.baseAddress();
}
}
while (true) {
long requiredSize = keyBuffer.remaining() + valueBuffer.remaining() + KEY_DATA_OFFSET;
if (Long.bitCount(requiredSize) != 1) {
requiredSize = Long.highestOneBit(requiredSize) << 1;
}
long nextChunkSize;
long nextChunkBaseAddress;
if (chunks.isEmpty()) {
nextChunkSize = requiredSize;
nextChunkBaseAddress = 0L;
} else {
FileChunk last = chunks.lastEntry().getValue();
nextChunkSize = max(min(last.capacity() << 1, maxChunkSize), requiredSize);
nextChunkBaseAddress = last.baseAddress() + last.capacity();
if (nextChunkSize < 0) {
return null;
}
}
FileChunk c;
try {
c = new FileChunk(nextChunkSize, nextChunkBaseAddress);
} catch (OutOfMemoryError e) {
return null;
}
chunks.put(c.baseAddress(), c);
Long address = c.writeMappingBuffers(keyBuffer, valueBuffer, hash);
if (address != null) {
return address + c.baseAddress();
}
}
}
@Override
public long getAllocatedMemory() {
long sum = 0;
for (FileChunk c : chunks.values()) {
sum += c.capacity();
}
return sum;
}
@Override
public long getOccupiedMemory() {
long sum = 0;
for (FileChunk c : chunks.values()) {
sum += c.occupied();
}
return sum;
}
@Override
public long getVitalMemory() {
return getAllocatedMemory();
}
@Override
public long getDataSize() {
long sum = 0;
for (FileChunk c : chunks.values()) {
sum += c.occupied();
}
return sum;
}
private FileChunk findChunk(long address) {
return chunks.floorEntry(address).getValue();
}
private int readIntFromChannel(long position) throws IOException {
ByteBuffer lengthBuffer = ByteBuffer.allocate(Integer.SIZE / Byte.SIZE);
for (int i = 0; lengthBuffer.hasRemaining(); ) {
int read = readFromChannel(lengthBuffer, position + i);
if (read < 0) {
throw new EOFException();
} else {
i += read;
}
}
return ((ByteBuffer) lengthBuffer.flip()).getInt();
}
private void writeIntToChannel(long position, int data) throws IOException {
ByteBuffer buffer = ByteBuffer.allocate(Integer.SIZE / Byte.SIZE);
buffer.putInt(data).flip();
writeBufferToChannel(position, buffer);
}
private void writeLongToChannel(long position, long data) throws IOException {
ByteBuffer buffer = ByteBuffer.allocate(Long.SIZE / Byte.SIZE);
buffer.putLong(data).flip();
writeBufferToChannel(position, buffer);
}
private void writeBufferToChannel(long position, ByteBuffer buffer) throws IOException {
for (int i = 0; buffer.hasRemaining(); ) {
int written = writeChannel.write(buffer, position + i);
if (written < 0) {
throw new EOFException();
} else {
i += written;
}
}
}
private int readFromChannel(ByteBuffer buffer, long position) throws IOException {
boolean interrupted = Thread.interrupted();
try {
while (true) {
FileChannel current = getReadableChannel();
try {
return readFromChannel(current, buffer, position);
} catch (ClosedChannelException e) {
interrupted |= Thread.interrupted();
FileChannel newChannel = source.getReadableChannel();
if (!readChannelReference.compareAndSet(current, newChannel)) {
newChannel.close();
} else {
LOGGER.info("Creating new read-channel for " + source.getFile().getName() + " as previous one was closed (likely due to interrupt)");
}
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
private FileChannel getReadableChannel() throws IOException {
FileChannel current = readChannelReference.get();
if (current == null) {
throw new IOException("Storage engine is closed");
}
return current;
}
private int readFromChannel(FileChannel channel, ByteBuffer buffer, long position) throws IOException {
int ret = channel.read(buffer, position);
if (ret < 0) {
ret = channel.read(buffer, position);
}
return ret;
}
@Override
public boolean shrink() {
final Lock ownerLock = owner.writeLock();
ownerLock.lock();
try {
if (chunks.isEmpty()) {
return false;
} else {
FileChunk candidate = chunks.lastEntry().getValue();
for (FileChunk c : chunks.descendingMap().values()) {
c.evictAll();
compress(c);
compress(candidate);
if (candidate.occupied() == 0) {
chunks.remove(candidate.baseAddress()).clear();
return true;
}
}
return false;
}
} finally {
ownerLock.unlock();
}
}
private void compress(FileChunk from) {
for (Long encoding : from.encodings()) {
ByteBuffer keyBuffer = readKeyBuffer(encoding);
int keyHash = readKeyHash(encoding);
ByteBuffer valueBuffer = readValueBuffer(encoding);
for (FileChunk to : chunks.headMap(from.baseAddress(), true).values()) {
Long address = to.writeMappingBuffers(keyBuffer, valueBuffer, keyHash);
if (address != null) {
long compressed = address + to.baseAddress();
if (compressed < encoding && owner.updateEncoding(keyHash, encoding, compressed, ~0)) {
free(encoding);
} else {
free(compressed);
}
break;
}
}
}
}
@Override
public void bind(Owner m) {
if (owner != null) {
throw new AssertionError();
}
owner = m;
}
class FileChunk {
private final AATreeFileAllocator allocator;
private final long filePosition;
private final long baseAddress;
private boolean valid = true;
FileChunk(long size, long baseAddress) {
Long newOffset = source.allocateRegion(size);
if (newOffset == null) {
throw new OutOfMemoryError("Storage engine file data area allocation failed:\nAllocator: " + source);
} else {
this.filePosition = newOffset;
}
this.allocator = new AATreeFileAllocator(size);
this.baseAddress = baseAddress;
}
FileChunk(ObjectInput input) throws IOException {
if (input.readInt() != MAGIC_CHUNK) {
throw new IOException("Wrong magic number");
}
this.filePosition = input.readLong();
this.baseAddress = input.readLong();
long size = input.readLong();
source.claimRegion(filePosition, size);
this.allocator = new AATreeFileAllocator(size, input);
}
ByteBuffer readKeyBuffer(long address) {
try {
long position = filePosition + address;
FileWriteTask pending = pendingWrites.get(position);
if (pending == null) {
int keyLength = readIntFromChannel(position + KEY_LENGTH_OFFSET);
return readBuffer(position + KEY_DATA_OFFSET, keyLength);
} else {
return pending.getKeyBuffer();
}
} catch (IOException e) {
throw new RuntimeException(e);
} catch (OutOfMemoryError e) {
LOGGER.error("Failed to allocate direct buffer for FileChannel read. "
+ "Consider increasing the -XX:MaxDirectMemorySize property to "
+ "allow enough space for the FileChannel transfer buffers");
throw e;
}
}
protected int readPojoHash(long address) {
try {
long position = filePosition + address;
FileWriteTask pending = pendingWrites.get(position);
if (pending == null) {
return readIntFromChannel(position + KEY_HASH_OFFSET);
} else {
return pending.pojoHash;
}
} catch (IOException e) {
throw new RuntimeException(e);
} catch (OutOfMemoryError e) {
LOGGER.error("Failed to allocate direct buffer for FileChannel read. "
+ "Consider increasing the -XX:MaxDirectMemorySize property to "
+ "allow enough space for the FileChannel transfer buffers");
throw e;
}
}
ByteBuffer readValueBuffer(long address) {
try {
long position = filePosition + address;
FileWriteTask pending = pendingWrites.get(position);
if (pending == null) {
int keyLength = readIntFromChannel(position + KEY_LENGTH_OFFSET);
int valueLength = readIntFromChannel(position + VALUE_LENGTH_OFFSET);
return readBuffer(position + keyLength + KEY_DATA_OFFSET, valueLength);
} else {
return pending.getValueBuffer();
}
} catch (IOException e) {
throw new RuntimeException(e);
} catch (OutOfMemoryError e) {
LOGGER.error("Failed to allocate direct buffer for FileChannel read. "
+ "Consider increasing the -XX:MaxDirectMemorySize property to "
+ "allow enough space for the FileChannel transfer buffers");
throw e;
}
}
ByteBuffer readBuffer(long position, int length) {
try {
ByteBuffer data = ByteBuffer.allocate(length);
for (int i = 0; data.hasRemaining(); ) {
int read = readFromChannel(data, position + i);
if (read < 0) {
throw new EOFException();
} else {
i += read;
}
}
return (ByteBuffer) data.rewind();
} catch (IOException e) {
throw new RuntimeException(e);
} catch (OutOfMemoryError e) {
LOGGER.error("Failed to allocate direct buffer for FileChannel read. "
+ "Consider increasing the -XX:MaxDirectMemorySize property to "
+ "allow enough space for the FileChannel transfer buffers");
throw e;
}
}
Long writeMappingBuffers(ByteBuffer keyBuffer, ByteBuffer valueBuffer, int pojoHash) {
int keyLength = keyBuffer.remaining();
int valueLength = valueBuffer.remaining();
long address = allocator.allocate(keyLength + valueLength + KEY_DATA_OFFSET);
if (address >= 0) {
long position = filePosition + address;
FileWriteTask task = new FileWriteTask(this, position, keyBuffer, valueBuffer, pojoHash);
pendingWrites.put(position, task);
writeExecutor.execute(task);
return address;
} else {
return null;
}
}
WriteContext getKeyWriteContext(long address) {
try {
long position = filePosition + address;
FileWriteTask pending = pendingWrites.get(position);
if (pending == null) {
int keyLength = readIntFromChannel(position + KEY_LENGTH_OFFSET);
return getDiskWriteContext(position + KEY_DATA_OFFSET, keyLength);
} else {
if (pendingWrites.get(position) != pending) {
return getKeyWriteContext(address);
} else {
return getQueuedWriteContext(pending, pending.getKeyBuffer());
}
}
} catch (IOException e) {
throw new RuntimeException(e);
}
}
WriteContext getValueWriteContext(long address) {
try {
long position = filePosition + address;
FileWriteTask pending = pendingWrites.get(position);
if (pending == null) {
int keyLength = readIntFromChannel(position + KEY_LENGTH_OFFSET);
int valueLength = readIntFromChannel(position + VALUE_LENGTH_OFFSET);
return getDiskWriteContext(position + keyLength + KEY_DATA_OFFSET, valueLength);
} else {
if (pendingWrites.get(position) != pending) {
return getValueWriteContext(address);
} else {
return getQueuedWriteContext(pending, pending.getValueBuffer());
}
}
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private WriteContext getDiskWriteContext(final long address, final int max) {
return new WriteContext() {
@Override
public void setLong(int offset, long value) {
if (offset < 0 || offset >= max) {
throw new IllegalArgumentException();
} else {
try {
writeLongToChannel(address + offset, value);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
@Override
public void flush() {
}
};
}
private WriteContext getQueuedWriteContext(final FileWriteTask current, final ByteBuffer queuedBuffer) {
return new WriteContext() {
@Override
public void setLong(int offset, long value) {
queuedBuffer.putLong(offset, value);
}
@Override
public void flush() {
FileWriteTask flush = new FileWriteTask(current.chunk, current.position, current.keyBuffer, current.valueBuffer, current.pojoHash);
pendingWrites.put(flush.position, flush);
writeExecutor.execute(flush);
}
};
}
void free(long address) {
try {
long position = filePosition + address;
int keyLength;
int valueLength;
FileWriteTask pending = pendingWrites.remove(position);
if (pending == null) {
keyLength = readIntFromChannel(position + KEY_LENGTH_OFFSET);
valueLength = readIntFromChannel(position + VALUE_LENGTH_OFFSET);
} else {
keyLength = pending.getKeyBuffer().remaining();
valueLength = pending.getValueBuffer().remaining();
}
allocator.free(address, keyLength + valueLength + KEY_DATA_OFFSET);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
synchronized void clear() {
source.freeRegion(filePosition);
valid = false;
}
long capacity() {
return allocator.capacity();
}
long occupied() {
return allocator.occupied();
}
long baseAddress() {
return baseAddress;
}
void persist(ObjectOutput output) throws IOException {
output.writeInt(MAGIC_CHUNK);
output.writeLong(filePosition);
output.writeLong(baseAddress);
output.writeLong(allocator.capacity());
allocator.persist(output);
}
synchronized boolean isValid() {
return valid;
}
Set<Long> encodings() {
Set<Long> encodings = new HashSet<>();
for (Long encoding : owner.encodingSet()) {
long relative = encoding - baseAddress();
if (relative >= 0 && relative < capacity()) {
encodings.add(encoding);
}
}
return encodings;
}
void evictAll() {
for (long encoding : encodings()) {
int slot = owner.getSlotForHashAndEncoding(readPojoHash(encoding - baseAddress()), encoding, ~0L);
owner.evict(slot, true);
}
}
}
class FileWriteTask implements Runnable {
private final FileChunk chunk;
private final ByteBuffer keyBuffer;
private final ByteBuffer valueBuffer;
private final int pojoHash;
private final long position;
FileWriteTask(FileChunk chunk, long position, ByteBuffer keyBuffer, ByteBuffer valueBuffer, int pojoHash) {
this.chunk = chunk;
this.position = position;
this.keyBuffer = keyBuffer;
this.valueBuffer = valueBuffer;
this.pojoHash = pojoHash;
}
@Override
public void run() {
if (pendingWrites.get(position) == this) {
try {
synchronized (chunk) {
if (chunk.isValid()) {
try {
try {
write();
} catch (IOException e) {
LOGGER.warn("Received IOException '{}' while trying to write @ {} : trying again", e.getMessage(), position);
write();
}
} catch (ClosedChannelException e) {
LOGGER.debug("DiskWriteTask terminated due to closed channel - we must be shutting down", e);
} catch (IOException e) {
LOGGER.warn("Received IOException '{}' during write @ {} : giving up", e.getMessage(), position);
} catch (OutOfMemoryError e) {
LOGGER.error("Failed to allocate a direct buffer for a FileChannel write. "
+ "Consider increasing the -XX:MaxDirectMemorySize property to "
+ "allow enough space for the FileChannel transfer buffers");
throw e;
}
}
}
} finally {
pendingWrites.remove(position, this);
}
}
}
private void write() throws IOException {
ByteBuffer key = getKeyBuffer();
ByteBuffer value = getValueBuffer();
int keyLength = key.remaining();
int valueLength = value.remaining();
writeIntToChannel(position + KEY_HASH_OFFSET, pojoHash);
writeIntToChannel(position + KEY_LENGTH_OFFSET, keyLength);
writeIntToChannel(position + VALUE_LENGTH_OFFSET, valueLength);
writeBufferToChannel(position + KEY_DATA_OFFSET, key);
writeBufferToChannel(position + KEY_DATA_OFFSET + keyLength, value);
long size = writeChannel.size();
long expected = position + keyLength + valueLength + KEY_DATA_OFFSET;
if (size < expected) {
throw new IOException("File size does not encompass last write [size:" + size + " end-of-write:" + expected);
}
}
ByteBuffer getKeyBuffer() {
return keyBuffer.duplicate();
}
ByteBuffer getValueBuffer() {
return valueBuffer.duplicate();
}
}
@Override
public int readKeyHash(long address) {
FileChunk chunk = findChunk(address);
return chunk.readPojoHash(address - chunk.baseAddress());
}
}
FileBackedStorageEngine
MAGIC: int
clearInternal(): void
FileChunk
