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package com.robrua.orianna.store;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import com.robrua.orianna.type.core.OriannaObject;
import com.robrua.orianna.type.exception.OriannaException;
/**
* A very simple filesystem-based DB
*
* @author Rob Rua ([email protected])
*/
public class FileSystemDB extends DataStore {
/**
* Iterator for DB entries on the file system
*
* @author Rob Rua ([email protected])
*/
public static class FSIterator> implements Iterator {
private final Class clazz;
private final Iterator files;
/**
* @param folder
* root DB folder for type
* @param clazz
* the type
*/
private FSIterator(final File folder, final Class clazz) {
files = Arrays.asList(folder.listFiles()).iterator();
this.clazz = clazz;
}
@Override
public boolean hasNext() {
return files.hasNext();
}
@Override
public T next() {
final File file = files.next();
return read(file, clazz);
}
}
private static final String HAVE_ALL_NAME = "meta";
/**
* Reads an object from a file
*
* @param file
* the file to read from
* @param type
* the type of the object stored
* @return the object in the file
*/
@SuppressWarnings("unchecked")
private static > T read(final File file, final Class type) {
try {
return (T)type.getDeclaredConstructors()[0].newInstance(readFile(file));
}
catch(InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | SecurityException e) {
return null;
}
}
/**
* Reads an object from a file
*
* @param file
* the file to read from
* @return the object in the file
*/
private static Object readFile(final File file) {
ObjectInputStream ois = null;
try {
ois = new ObjectInputStream(new FileInputStream(file));
return ois.readObject();
}
catch(IOException | ClassNotFoundException e) {
throw new OriannaException("Unable to read file!");
}
finally {
if(ois != null) {
try {
ois.close();
}
catch(final IOException e) {
throw new OriannaException("Unable to close file stream!");
}
}
}
}
/**
* Writes an object to a file
*
* @param file
* the file to write to
* @param object
* the object to write
*/
private static void write(final File file, final OriannaObject object) {
writeFile(file, object.getDto());
}
/**
* Writes an object to a file
*
* @param file
* the file to write to
* @param object
* the object to write
*/
private static void writeFile(final File file, final Object object) {
ObjectOutputStream oos = null;
try {
oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(object);
}
catch(final IOException e) {
throw new OriannaException("Unable to write to file!");
}
finally {
if(oos != null) {
try {
oos.close();
}
catch(final IOException e) {
throw new OriannaException("Unable to close file stream!");
}
}
}
}
private final Map>, Boolean> haveAll;
private final File root;
/**
* @param root
* the root folder of the DB
*/
@SuppressWarnings("unchecked")
public FileSystemDB(final File root) {
if(root == null || root.exists() && !root.isDirectory()) {
throw new IllegalArgumentException("Root file must be a directory!");
}
this.root = root;
if(!root.exists()) {
root.mkdirs();
}
final File allFile = new File(root, HAVE_ALL_NAME);
if(!allFile.exists()) {
haveAll = new HashMap<>();
}
else {
haveAll = (HashMap>, Boolean>)readFile(allFile);
}
}
/**
* @param rootPath
* the path to the root folder of the DB
*/
public FileSystemDB(final String rootPath) {
this(new File(rootPath));
}
@Override
protected boolean allowsNullStoreKeys() {
return false;
}
@Override
protected > boolean checkHasAll(final Class type) {
final Boolean val = haveAll.get(type);
if(val == null) {
return false;
}
return val.booleanValue();
}
@Override
protected > void doDelete(final Class type, final List keys) {
final File folder = getFolder(type);
for(final Object key : keys) {
final File file = getFile(folder, key);
if(file.exists()) {
file.delete();
}
}
}
@Override
protected > void doDelete(final Class type, final Object key) {
final File file = getFile(getFolder(type), key);
if(file.exists()) {
file.delete();
}
}
@Override
protected > List doGet(final Class type, final List keys) {
final File folder = getFolder(type);
final List result = new ArrayList<>(keys.size());
for(final Object key : keys) {
final File file = getFile(folder, key);
if(file.exists()) {
result.add(read(file, type));
}
else {
result.add(null);
}
}
return result;
}
@Override
protected > T doGet(final Class type, final Object key) {
final File file = getFile(getFolder(type), key);
if(!file.exists()) {
return null;
}
return read(file, type);
}
@Override
protected > List doGetAll(final Class type) {
final File folder = getFolder(type);
final List result = new ArrayList<>();
for(final File file : folder.listFiles()) {
result.add(read(file, type));
}
return result;
}
@Override
public > CloseableIterator doGetIterator(final Class type) {
final File folder = getFolder(type);
return CloseableIterator.fromIterator(new FSIterator<>(folder, type));
}
@SuppressWarnings("unchecked")
@Override
protected > void doStore(final List objs, final List keys, final boolean isFullSet) {
final Class type = (Class)objs.get(0).getClass();
if(isFullSet) {
haveAll.put(type, Boolean.TRUE);
writeFile(new File(root, HAVE_ALL_NAME), haveAll);
}
final File folder = getFolder(type);
for(int i = 0; i < objs.size(); i++) {
write(getFile(folder, keys.get(i)), objs.get(i));
}
}
@Override
protected > void doStore(final T obj, final Object key) {
write(getFile(getFolder(obj.getClass()), key), obj);
}
/**
* @param folder
* the folder for the object's type
* @param key
* the key
* @return the file that the key is or would be stored in
*/
private File getFile(final File folder, final Object key) {
final int hashCode = Arrays.hashCode(new Object[] {key, key.getClass()});
return new File(folder, Integer.toString(hashCode));
}
/**
* @param type
* a type
* @return the folder objects of that type are found in
*/
private File getFolder(final Class type) {
final File folder = new File(root, Integer.toString(type.getCanonicalName().hashCode()));
if(!folder.exists()) {
folder.mkdir();
}
return folder;
}
}
