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/*
* @(#)PHashMapMMF.java 1.6 08/28/07
*/
package com.sun.messaging.jmq.io.disk;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.io.*;
import java.nio.*;
/**
* PHashMapMMF is a persistent HashMap that is backed by a memory-mapped file.
* Due to the nature of memory-mapped file, PHashMapMMF implementation can
* provide partial entry udpate optimization which greatly improves PHashMap
* update performance. In a standard PHashMap, the key and value object is
* either serialized or externalized as a VRecord and it is written to the
* backing file when an entry is updated, i.e. even when only a single field
* in the value object is modified. Partial entry update optimization is
* implemented by providing a client data section as part of the record and
* additional APIs to update just the client data section of the record.
* So instead of rewriting the whole record, the user of this class can just
* update the client data portion of the record, e.g. value of the modified
* field for the value object.
*
* Note: to use partial entry update optimization, the user of the this class
* is responsible for processing the client data and update the value object
* when PHashMapMMF is loaded (see
* com.sun.messaging.jmq.jmsserver.persist.file.TidList for example usage).
*
* Each record has the following layout:
*
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| record header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| serialized key object |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| serialized value object |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|%CD| client data section (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
public class PHashMapMMF extends PHashMap {
// Client data info for partial entry udpate optimization
static final byte[] CLIENT_DATA_MARKER = {'%', 'C', 'D'}; // CD's marker
static final byte[] EMPTY_CLIENT_DATA_MARKER = {0, 0, 0}; // Empty marker
int maxClientDataSize = 0; // size of client data (# bytes)
/**
* Construct the hash table backed by the specified file.
* If the file exists, the hash table will be initialized
* with entries from the file.
* @param filename Backing file.
* @param safe Indicate whether the underlying file
* should be sync'ed as soon as possible.
* @param reset If true, all data in the file will be cleared.
*/
public PHashMapMMF(File filename, boolean safe, boolean reset, boolean isMinimumWrites, boolean interruptSafe)
throws IOException {
this(filename, VRFileMap.DEFAULT_INITIAL_FILE_SIZE,
DEFAULT_INITIAL_MAP_CAPACITY, safe, reset, isMinimumWrites, interruptSafe);
}
/**
* Construct the hash table backed by the specified file.
* If the file exists, the hash table will be initialized
* with entries from the file.
* @param filename Backing file.
* @param size Initialize size of backing file.
* @param safe Indicate whether the underlying file
* should be sync'ed as soon as possible.
* @param reset If true, all data in the file will be cleared.
*/
public PHashMapMMF(File filename, long size, boolean safe, boolean reset, boolean isMinimumWrites, boolean interruptSafe)
throws IOException {
super(filename, size, DEFAULT_INITIAL_MAP_CAPACITY, safe, reset, isMinimumWrites, interruptSafe);
}
/**
* Construct the hash table backed by the specified file.
* If the file exists, the hash table will be initialized
* with entries from the file.
* @param filename Backing file.
* @param size Initialize size of backing file.
* @param mapCapacity Initialize map capacity.
* @param safe Indicate whether the underlying file
* should be sync'ed as soon as possible.
* @param reset If true, all data in the file will be cleared.
*/
public PHashMapMMF(File filename, long size, int mapCapacity,
boolean safe, boolean reset, boolean isMinimumWrites, boolean interruptSafe) throws IOException {
super(filename, size, mapCapacity, safe, reset, isMinimumWrites, interruptSafe);
}
protected void initBackingFile(File filename, long size, boolean isMinimumWrites, boolean interruptSafe) {
backingFile = new VRFileMap(filename, size, isMinimumWrites, interruptSafe);
}
public void intClientData(int size) {
if (size <= 0) {
throw new IllegalArgumentException("Invalid client data size");
}
maxClientDataSize = size;
}
public void load(ObjectInputStreamCallback ocb) throws IOException, ClassNotFoundException,
PHashMapLoadException {
PHashMapLoadException loadException = null;
Set entries = backingFile.getRecords();
int eSize = entries.size();
int mSize = this.size();
if (eSize > mSize) {
recordMap = new ConcurrentHashMap(eSize);
} else {
recordMap = new ConcurrentHashMap(mSize);
}
Iterator iter = entries.iterator();
while (iter.hasNext()) {
VRecordMap record = (VRecordMap)iter.next();
Object key = null;
Object value = null;
Throwable kex = null;
Throwable vex = null;
Throwable ex = null;
try {
ByteBuffer buffer = record.getBuffer();
buffer.position(0);
int limit = buffer.limit();
byte[] data = new byte[limit];
buffer.get(data);
ByteArrayInputStream bais = new ByteArrayInputStream(data);
// Use our version of ObjectInputStream so we can load old
// serialized object from an old store, i.e. store migration
ObjectInputStream ois = ocb.getObjectInputStream(bais);
try {
key = ois.readObject();
} catch (Throwable e) {
if (e instanceof ClassNotFoundException) {
throw (ClassNotFoundException)e;
} else {
kex = e;
}
}
try {
value = ois.readObject();
} catch (Throwable e) {
if (e instanceof ClassNotFoundException) {
throw (ClassNotFoundException)e;
} else {
vex = e;
}
}
// Mark client data starting position
if (maxClientDataSize > 0) {
// Since we've read in all data in the buffer, we need to
// reset the position back to client data starting position
int pos = limit - bais.available();
buffer.position(pos);
buffer.mark();
}
ois.close();
bais.close();
} catch (IOException e) {
ex = e;
}
if (kex != null || vex != null || ex != null) {
PHashMapLoadException le = new PHashMapLoadException(
"Failed to load data in [" + record.toString() + "]");
le.setKey(key);
le.setValue(value);
le.setKeyCause(kex);
le.setValueCause(vex);
le.setNextException(loadException);
le.initCause(ex);
loadException = le;
if (key != null && value != null) {
// we have the key, keep the record
recordMap.put(key, record);
putInHashMap(key, value, false);
} else {
// delete bad record
backingFile.free(record);
}
} else {
// cache info
recordMap.put(key, record);
putInHashMap(key, value, false);
}
}
loaded = true;
if (loadException != null) {
throw loadException;
}
}
/**
* Maps the specified key to the specified value in this HashMap.
* The entry will be persisted in the backing file.
*/
Object doPut(Object key, Object value, boolean putIfAbsent) {
checkLoaded();
boolean error = false;
Object oldValue = null;
try {
oldValue = putInHashMap(key, value, putIfAbsent);
if (putIfAbsent && (oldValue != null)) {
// nothing to do since there was a mapping for key
return oldValue;
}
// serialize the key and value
ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
ObjectOutputStream bos = new ObjectOutputStream(baos);
bos.writeObject(key);
bos.writeObject(value);
bos.close();
byte[] data = baos.toByteArray();
int dataLength = data.length;
if (maxClientDataSize > 0) {
// Add addtional space for client data and marker
// to indicate the existence of client data
dataLength += maxClientDataSize + CLIENT_DATA_MARKER.length;
}
VRecordMap record = (VRecordMap)recordMap.get(key);
synchronized (backingFile) {
if (record == null) {
record = (VRecordMap)backingFile.allocate(dataLength);
} else {
if (record.getDataCapacity() < dataLength) {
// need another VRecordMap
backingFile.free(record);
record = (VRecordMap)backingFile.allocate(dataLength);
}
}
MappedByteBuffer buffer = (MappedByteBuffer)record.getBuffer();
buffer.rewind();
buffer.put(data);
// Mark client data starting position
if (maxClientDataSize > 0) {
buffer.mark();
// Clear the old data by removing the old's marker
buffer.put(EMPTY_CLIENT_DATA_MARKER);
// Now, resets buffer's to starting position of client data
buffer.reset();
}
if (safe) {
record.force();
}
}
// update internal records map
recordMap.put(key, record);
} catch (IOException e) {
throw new RuntimeException(e);
} finally {
if (error) {
if (oldValue == null) {
super.remove(key);
} else {
putInHashMap(key, oldValue, false); // put back the old value
}
}
}
return oldValue;
}
/**
* Update the client data section of the record.
*
* @param key key with which the specified client data is to be associated
* @param cData client data to be associated with the specified key
* @exception IllegalStateException if client data size has not been
* initialized or the record is not found
*/
public final void putClientData(Object key, byte[] cData) {
checkLoaded();
if (maxClientDataSize <= 0) {
throw new IllegalStateException(
"Client data size has not been initialized");
}
if (cData.length > maxClientDataSize) {
throw new IllegalArgumentException(
"Client data size of " + cData.length +
" bytes is larger than the byte limit (maxClientDataSize) of " +
maxClientDataSize + " [key=" + key + ", cData=" + cData + "]");
}
VRecordMap record = (VRecordMap)recordMap.get(key);
if (record == null) {
throw new IllegalStateException(
"Record not found [key=" + key + ", cData=" + cData + "]");
}
try {
synchronized (backingFile) {
// Just update the client data portion of the record
MappedByteBuffer buffer = (MappedByteBuffer)record.getBuffer();
try {
// Resets buffer's to starting position of client data
buffer.reset();
} catch (InvalidMarkException e) {
// Try to reset the marker
setClientDataMarker(buffer);
}
buffer.put(CLIENT_DATA_MARKER); // Put marker
buffer.put(cData); // Put client data
if (safe) {
record.force();
}
}
// update internal HashMap
recordMap.put(key, record);
} catch (IOException e) {
throw new RuntimeException(
"Unable to update client data [key=" + key +
", cData=" + cData + "]", e);
}
}
/**
* Get client data for the specified key; null if there's none.
*/
public final byte[] getClientData(Object key) {
byte[] cData = null;
// load client data if available
try {
if (maxClientDataSize > 0) {
VRecordMap record = (VRecordMap)recordMap.get(key);
if (record != null) {
synchronized (backingFile) {
ByteBuffer buffer = record.getBuffer();
// Resets buffer's to starting position of client data
try {
buffer.reset();
} catch (InvalidMarkException e) {
// Try to reset the marker
setClientDataMarker(buffer);
}
// Check for existence of client data marker, i.e. "%CD"
byte b1 = buffer.get();
byte b2 = buffer.get();
byte b3 = buffer.get();
if (b1 == CLIENT_DATA_MARKER[0] &&
b2 == CLIENT_DATA_MARKER[1] &&
b3 == CLIENT_DATA_MARKER[2]) {
cData = new byte[maxClientDataSize];
buffer.get(cData); // Read in client data
}
}
}
}
} catch (Throwable e) {
throw new RuntimeException(e);
}
return cData;
}
/**
* Mark starting position of client data for the specified ByteBuffer.
*
* Note:
* Calling method is responsible for synchronize on VRFile (backing file).
*/
private void setClientDataMarker(ByteBuffer buffer) {
// Try to look for the marker, i.e. "%CD"
for (int i = 0, limit = buffer.limit(); i < limit; i++) {
if (buffer.get(i) == CLIENT_DATA_MARKER[0]) {
// Found '%', so check if the next 2 bytes is "CD"
if ((i + 2) < limit &&
buffer.get(i+1) == CLIENT_DATA_MARKER[1] &&
buffer.get(i+2) == CLIENT_DATA_MARKER[2]) {
buffer.position(i);
buffer.mark();
return; // marker has been found and set
}
}
}
// Record doesn't contain client data so just reset the marker at the
// end of the value object; the position where client data should start.
// The crude way to do this is to re-read the key and value object.
Object key = null;
Object value = null;
Throwable kex = null;
Throwable vex = null;
Throwable ex = null;
try {
buffer.position(0);
int limit = buffer.limit();
byte[] data = new byte[limit];
buffer.get(data);
ByteArrayInputStream bais = new ByteArrayInputStream(data);
ObjectInputStream ois = new ObjectInputStream(bais);
try {
key = ois.readObject();
} catch (Throwable e) {
kex = e;
}
try {
value = ois.readObject();
} catch (Throwable e) {
vex = e;
}
// Mark starting position of client data
if (maxClientDataSize > 0) {
// Since we've already read in the whole buffer we need to
// reset buffer's position back to the start of client data
int pos = limit - bais.available();
buffer.position(pos);
buffer.mark();
}
ois.close();
bais.close();
} catch (IOException e) {
ex = e;
}
if (kex != null || vex != null || ex != null) {
PHashMapLoadException le = new PHashMapLoadException(
"Failed to set client data marker");
le.setKey(key);
le.setValue(value);
le.setKeyCause(kex);
le.setValueCause(vex);
le.initCause(ex);
throw new RuntimeException(le);
}
}
}
