Merge remote-tracking branch 'origin/master'

This commit is contained in:
Peter Lawrey
2015-04-25 10:43:16 +01:00
8 changed files with 453 additions and 283 deletions
@@ -40,6 +40,7 @@ import static java.util.Collections.emptyList;
import static net.openhft.chronicle.engine.client.ClientWiredStatelessTcpConnectionHub.CoreFields.reply;
import static net.openhft.chronicle.map.MapWireHandler.EventId;
import static net.openhft.chronicle.map.MapWireHandler.EventId.*;
import static net.openhft.chronicle.map.VanillaChronicleMap.newInstance;
/**
@@ -51,24 +52,19 @@ class ClientWiredStatelessChronicleMap<K, V> extends MapStatelessClient<K, V, Ev
private static final Logger LOG =
LoggerFactory.getLogger(ClientWiredStatelessChronicleMap.class);
public static final Consumer<ValueOut> VOID_PARAMETERS = out -> out.marshallable(AbstactStatelessClient.EMPTY);
private final Class vClass;
protected Class<K> kClass;
private boolean putReturnsNull;
private boolean removeReturnsNull;
// used with toString()
private static final int MAX_NUM_ENTRIES = 20;
public ClientWiredStatelessChronicleMap(
@NotNull final ClientWiredChronicleMapStatelessBuilder config,
@NotNull final Class kClass,
@NotNull final Class vClass,
@NotNull final String channelName,
ClientWiredStatelessTcpConnectionHub hub) {
@NotNull final ClientWiredStatelessTcpConnectionHub hub) {
super(channelName, hub, "MAP", 0, vClass);
this.putReturnsNull = config.putReturnsNull();
@@ -96,12 +92,12 @@ class ClientWiredStatelessChronicleMap<K, V> extends MapStatelessClient<K, V, Ev
@Override
public V newValueInstance() {
return (V) VanillaChronicleMap.newInstance(vClass, false);
return (V) newInstance(vClass, false);
}
@Override
public K newKeyInstance() {
return VanillaChronicleMap.newInstance(kClass, true);
return newInstance(kClass, true);
}
@Override
@@ -210,8 +206,7 @@ class ClientWiredStatelessChronicleMap<K, V> extends MapStatelessClient<K, V, Ev
@NotNull
public String toString() {
return "";
return "todo";
}
@NotNull
@@ -224,7 +219,7 @@ class ClientWiredStatelessChronicleMap<K, V> extends MapStatelessClient<K, V, Ev
}
public boolean containsKey(Object key) {
return proxyReturnBoolean(containsKey, out -> writeField(out, (K) key));
return proxyReturnBoolean(containsKey, out -> out.object(key));
}
@NotNull
@@ -233,7 +228,7 @@ class ClientWiredStatelessChronicleMap<K, V> extends MapStatelessClient<K, V, Ev
}
public boolean containsValue(Object value) {
return proxyReturnBoolean(containsValue, out -> writeField(out, (V) value));
return proxyReturnBoolean(containsValue, out -> out.object(value));
}
public void putAll(@NotNull Map<? extends K, ? extends V> map) {
@@ -80,7 +80,7 @@ public class EngineMap<K, V> implements ChronicleMap<K, V> {
if (b == null)
return null;
final Wire wire = toWire();
AbstactStatelessClient.writeField(b, wire.getValueOut());
wire.getValueOut().object(b);
wire.bytes().flip();
return toWire().getValueIn().bytes();
@@ -160,13 +160,12 @@ public class EngineMap<K, V> implements ChronicleMap<K, V> {
return null;
final Wire wire = toWire(bytes);
buffer.flip();
return AbstactStatelessClient.readObject(wire.getValueIn(), null, eClass);
return wire.getValueIn().object(eClass);
}
@Override
public V put(final K key, final V value) {
nullCheck(key);
// nullCheck(value);
return toObject(vClass, () -> map.put(bytes(key), bytes(value)));
}
@@ -0,0 +1,62 @@
package net.openhft.chronicle.map;
/**
* Created by daniel on 23/04/15.
*/
public class FPMEvent {
public enum EventType {NEW, UPDATE, DELETE}
private EventType eventType;
private boolean programmatic;
private String key;
private String value;
public FPMEvent(EventType eventType, boolean programmatic, String key, String value) {
this.eventType = eventType;
this.programmatic = programmatic;
this.key = key;
this.value = value;
}
public EventType getEventType() {
return eventType;
}
public void setEventType(EventType eventType) {
this.eventType = eventType;
}
public boolean isProgrammatic() {
return programmatic;
}
public void setProgrammatic(boolean programmatic) {
this.programmatic = programmatic;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
@Override
public String toString() {
return "FPMEvent{" +
"eventType=" + eventType +
", programmatic=" + programmatic +
", key='" + key + '\'' +
", value='" + value + '\'' +
'}';
}
}
@@ -0,0 +1,199 @@
package net.openhft.chronicle.map;
import net.openhft.chronicle.hash.function.SerializableFunction;
import org.jetbrains.annotations.NotNull;
import java.io.File;
import java.io.IOException;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import java.util.function.Consumer;
import java.util.function.Predicate;
/**
* Created by daniel on 22/04/15.
*/
public class FilePerKeyChronicleMap implements ChronicleMap<String, String> {
private final ChronicleMap<String, String> chMap;
private final FilePerKeyMap fpMap;
public FilePerKeyChronicleMap(String dir) {
fpMap = new FilePerKeyMap(dir);
chMap = ChronicleMapBuilder.of(String.class, String.class)
.entries(500).averageValueSize(2_000_000).create();
}
@Override
public int size() {
return fpMap.size();
}
@Override
public boolean isEmpty() {
return fpMap.isEmpty();
}
@Override
public boolean containsKey(Object key) {
return fpMap.containsKey(key);
}
@Override
public boolean containsValue(Object value) {
return fpMap.containsValue(value);
}
@Override
public String get(Object key) {
return fpMap.get(key);
}
@Override
public String put(String key, String value) {
fpMap.put(key, value);
return chMap.put(key,value);
}
@Override
public String remove(Object key) {
chMap.remove(key);
return fpMap.remove(key);
}
@Override
public void putAll(Map<? extends String, ? extends String> m) {
fpMap.putAll(m);
chMap.putAll(m);
}
@Override
public void clear() {
fpMap.clear();
}
@NotNull
@Override
public Set<String> keySet() {
return fpMap.keySet();
}
@NotNull
@Override
public Collection<String> values() {
return fpMap.values();
}
@NotNull
@Override
public Set<Entry<String, String>> entrySet() {
return fpMap.entrySet();
}
@Override
public String getUsing(String key, String usingValue) {
return chMap.getUsing(key, usingValue);
}
@Override
public String acquireUsing(@NotNull String key, String usingValue) {
//@todo ADD THE LOGIC FOR FPMAP
return chMap.acquireUsing(key, usingValue);
}
@NotNull
@Override
public MapKeyContext<String, String> acquireContext(@NotNull String key, @NotNull String usingValue) {
return chMap.acquireContext(key,usingValue);
}
@Override
public <R> R getMapped(String key, @NotNull SerializableFunction<? super String, R> function) {
return chMap.getMapped(key, function);
}
@Override
public String putMapped(String key, @NotNull UnaryOperator<String> unaryOperator) {
throw new UnsupportedOperationException();
}
@Override
public void getAll(File toFile) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public void putAll(File fromFile) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public String newValueInstance() {
return new String();
}
@Override
public String newKeyInstance() {
return new String();
}
@Override
public Class<String> valueClass() {
return String.class;
}
@Override
public File file() {
throw new UnsupportedOperationException();
}
@Override
public long longSize() {
return size();
}
@Override
public MapKeyContext<String, String> context(String key) {
return chMap.context(key);
}
@Override
public Class<String> keyClass() {
return String.class;
}
@Override
public boolean forEachEntryWhile(Predicate<? super MapKeyContext<String, String>> predicate) {
return chMap.forEachEntryWhile(predicate);
}
@Override
public void forEachEntry(Consumer<? super MapKeyContext<String, String>> action) {
chMap.forEachEntry(action);
}
@Override
public void close() {
chMap.close();
}
@Override
public String putIfAbsent(String key, String value) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(Object key, Object value) {
throw new UnsupportedOperationException();
}
@Override
public boolean replace(String key, String oldValue, String newValue) {
throw new UnsupportedOperationException();
}
@Override
public String replace(String key, String value) {
throw new UnsupportedOperationException();
}
}
@@ -1,7 +1,6 @@
package net.openhft.chronicle.map;
import com.sun.nio.file.SensitivityWatchEventModifier;
import net.openhft.chronicle.hash.function.SerializableFunction;
import org.jetbrains.annotations.NotNull;
import java.io.File;
@@ -10,112 +9,47 @@ import java.nio.file.*;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* Created by daniel on 22/04/15.
*
*/
public class FilePerKeyMap<K, V> implements ChronicleMap<K, V> {
private String dir;
private Path dirPath;
private Map<File, Long> lastModifiedByProgram = new ConcurrentHashMap<>();
public class FilePerKeyMap implements Map<String, String> {
private final String dir;
private final Path dirPath;
private final Map<File, Long> lastModifiedByProgram = new ConcurrentHashMap<>();
private final List<Consumer<FPMEvent>> listeners = new ArrayList<>();
private final FPMWatcher fileFpmWatcher = new FPMWatcher();
public FilePerKeyMap(String dir) {
public FilePerKeyMap(String dir){
this.dir = dir;
this.dirPath = Paths.get(dir);
try {
this.dir = dir;
dirPath = Paths.get(dir);
Files.createDirectories(dirPath);
new Thread("WatcherThread") {
public void run() {
try {
WatchService watcher = FileSystems.getDefault().newWatchService();
dirPath.register(watcher, new WatchEvent.Kind[]{
StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_DELETE,
StandardWatchEventKinds.ENTRY_MODIFY},
SensitivityWatchEventModifier.HIGH
);
while(true){
WatchKey key = null;
try {
key = watcher.take();
System.out.println("Event Taken");
for (WatchEvent<?> event : key.pollEvents()) {
// get event type
WatchEvent.Kind<?> kind = event.kind();
// get file name
@SuppressWarnings("unchecked")
WatchEvent<Path> ev = (WatchEvent<Path>) event;
Path fileName = ev.context();
String mapKey = fileName.toString();
if (kind == StandardWatchEventKinds.OVERFLOW) {
System.out.println("OVERFLOW");
continue;
} else if (kind == StandardWatchEventKinds.ENTRY_CREATE) {
Path p = dirPath.resolve(fileName);
String mapVal = getFileContents(p);
if(isProgrammaticUpdate(p.toFile())){
System.out.println("Programmatic create to " + mapKey);// + " : " + mapVal);
}else {
System.out.println("created " + mapKey);// + " : " + mapVal);
}
} else if (kind == StandardWatchEventKinds.ENTRY_DELETE) {
Path p = dirPath.resolve(fileName);
if(isProgrammaticUpdate(p.toFile())){
System.out.println("Programmatic delete to " + mapKey);
lastModifiedByProgram.remove(p.toFile());
}else {
System.out.println("User delete " + mapKey);
}
} else if (kind == StandardWatchEventKinds.ENTRY_MODIFY) {
Path p = dirPath.resolve(fileName);
String mapVal = getFileContents(p);
if(isProgrammaticUpdate(p.toFile())){
System.out.println("Programmatic update to " + mapKey);// + " : " + mapVal);
}else {
System.out.println("User modified " + mapKey + " : ");// + mapVal);
}
}
}
} catch (InterruptedException e) {
System.out.println("Watcher service exiting");
return;
}finally{
key.reset();
}
}
} catch (IOException e) {
throw new AssertionError(e);
}
}
}.start();
} catch (IOException e) {
throw new AssertionError(e);
}catch (IOException e){
throw new RuntimeException(e);
}
fileFpmWatcher.start();
}
private boolean isProgrammaticUpdate(File file){
if(lastModifiedByProgram.containsKey(file)){
return file.lastModified() == lastModifiedByProgram.get(file) ? true : false;
}else{
return false;
public void registerForEvents(Consumer<FPMEvent> listener){
listeners.add(listener);
}
public void unregisterForEvents(Consumer<FPMEvent> listener){
listeners.remove(listener);
}
private void fireEvent(FPMEvent event){
for (Consumer<FPMEvent> listener : listeners) {
listener.accept(event);
}
}
@Override
public int size() {
return (int)getFiles(dirPath).count();
return (int)getFiles().count();
}
@Override
@@ -125,184 +59,78 @@ public class FilePerKeyMap<K, V> implements ChronicleMap<K, V> {
@Override
public boolean containsKey(Object key) {
return getFiles(dirPath).anyMatch(p->p.getFileName().toString().equals(key));
return getFiles().anyMatch(p->p.getFileName().toString().equals(key));
}
@Override
public boolean containsValue(Object value) {
return getFiles(dirPath).anyMatch(p->getFileContents(p).equals(value));
return getFiles().anyMatch(p->getFileContents(p).equals(value));
}
@Override
public V get(Object key) {
checkTypeIsString(key);
Path path = Paths.get(dir,(String)key);
return (V)getFileContents(path);
public String get(Object key) {
Path path = dirPath.resolve((String) key);
return getFileContents(path);
}
@Override
public V put(K key, V value) {
checkTypeIsString(key, value);
Path path = Paths.get(dir,(String)key);
public String put(String key, String value) {
Path path = dirPath.resolve(key);
String existingValue = getFileContents(path);
writeToFile(path, (String) value);
writeToFile(path, value);
return (V) existingValue;
return existingValue;
}
@Override
public V remove(Object key) {
String existing = (String)get(key);
public String remove(Object key) {
String existing = get(key);
if(existing != null){
deleteFile(Paths.get(dir, (String)key));
}
return (V)existing;
return existing;
}
@Override
public void putAll(Map<? extends K, ? extends V> m) {
public void putAll(Map<? extends String, ? extends String> m) {
m.entrySet().stream().forEach(e->put(e.getKey(), e.getValue()));
}
@Override
public void clear() {
getFiles(dirPath).forEach(this::deleteFile);
getFiles().forEach(this::deleteFile);
}
@NotNull
@Override
public Set<K> keySet() {
return getFiles(dirPath).map(p -> (K) p.getFileName().toString())
.collect(Collectors.toSet());
}
@NotNull
@Override
public Collection<V> values() {
return getFiles(dirPath).map(p -> (V) getFileContents(p))
public Set<String> keySet() {
return getFiles().map(p -> p.getFileName().toString())
.collect(Collectors.toSet());
}
@NotNull
@Override
public Set<Entry<K, V>> entrySet() {
return getFiles(dirPath).map(p ->
(Entry<K, V>) new FPMEntry(p.getFileName().toString(), getFileContents(p)))
public Collection<String> values() {
return getFiles().map(p -> getFileContents(p))
.collect(Collectors.toSet());
}
@Override
public V getUsing(K key, V usingValue) {
return null;
}
@Override
public V acquireUsing(@NotNull K key, V usingValue) {
return null;
}
@NotNull
@Override
public MapKeyContext<K, V> acquireContext(@NotNull K key, @NotNull V usingValue) {
return null;
}
@Override
public <R> R getMapped(K key, @NotNull SerializableFunction<? super V, R> function) {
return null;
}
@Override
public V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator) {
return null;
}
@Override
public void getAll(File toFile) throws IOException {
}
@Override
public void putAll(File fromFile) throws IOException {
}
@Override
public V newValueInstance() {
return null;
}
@Override
public K newKeyInstance() {
return null;
}
@Override
public Class<V> valueClass() {
return null;
}
@Override
public File file() {
return null;
}
@Override
public long longSize() {
return 0;
}
@Override
public MapKeyContext<K, V> context(K key) {
return null;
}
@Override
public Class<K> keyClass() {
return null;
}
@Override
public boolean forEachEntryWhile(Predicate<? super MapKeyContext<K, V>> predicate) {
return false;
}
@Override
public void forEachEntry(Consumer<? super MapKeyContext<K, V>> action) {
}
@Override
public void close() {
}
@Override
public V putIfAbsent(K key, V value) {
return null;
}
@Override
public boolean remove(Object key, Object value) {
return false;
}
@Override
public boolean replace(K key, V oldValue, V newValue) {
return false;
}
@Override
public V replace(K key, V value) {
return null;
public Set<Entry<String, String>> entrySet() {
return getFiles().map(p ->
(Entry<String, String>) new FPMEntry(p.getFileName().toString(), getFileContents(p)))
.collect(Collectors.toSet());
}
private Stream<Path> getFiles(Path path){
private Stream<Path> getFiles(){
try {
return Files.walk(path).filter(p -> !Files.isDirectory(p));
return Files.walk(dirPath).filter(p -> !Files.isDirectory(p));
} catch (IOException e) {
throw new AssertionError(e);
}
@@ -340,39 +168,35 @@ public class FilePerKeyMap<K, V> implements ChronicleMap<K, V> {
}
}
private void checkTypeIsString(Object... objs) {
for(Object o : objs){
if(!(o instanceof String))
throw new AssertionError("FilePerKeyMap only accepts Key and Values " +
"of type String. Unsupported type: '" + o + "'");
}
public void close(){
fileFpmWatcher.interrupt();
}
private static class FPMEntry<K,V> implements Entry
private static class FPMEntry<String> implements Entry<String, String>
{
private K key;
private V value;
private String key;
private String value;
public FPMEntry(K key, V value){
public FPMEntry(String key, String value){
this.key = key;
this.value = value;
}
@Override
public K getKey() {
public String getKey() {
return key;
}
@Override
public V getValue() {
public String getValue() {
return value;
}
@Override
public Object setValue(Object value) {
throw new UnsupportedOperationException();
public String setValue(String value) {
String lastValue = this.value;
this.value = value;
return lastValue;
}
@Override
@@ -380,10 +204,10 @@ public class FilePerKeyMap<K, V> implements ChronicleMap<K, V> {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
FPMEntry<?, ?> entry = (FPMEntry<?, ?>) o;
FPMEntry<?> fpmEntry = (FPMEntry<?>) o;
if (key != null ? !key.equals(entry.key) : entry.key != null) return false;
return !(value != null ? !value.equals(entry.value) : entry.value != null);
if (key != null ? !key.equals(fpmEntry.key) : fpmEntry.key != null) return false;
return !(value != null ? !value.equals(fpmEntry.value) : fpmEntry.value != null);
}
@@ -394,4 +218,77 @@ public class FilePerKeyMap<K, V> implements ChronicleMap<K, V> {
return result;
}
}
private class FPMWatcher extends Thread{
@Override
public void run(){
try {
WatchService watcher = FileSystems.getDefault().newWatchService();
dirPath.register(watcher, new WatchEvent.Kind[]{
StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_DELETE,
StandardWatchEventKinds.ENTRY_MODIFY},
SensitivityWatchEventModifier.HIGH
);
while(true){
WatchKey key = null;
try {
key = watcher.take();
for (WatchEvent<?> event : key.pollEvents()) {
// get event type
WatchEvent.Kind<?> kind = event.kind();
// get file name
WatchEvent<Path> ev = (WatchEvent<Path>) event;
Path fileName = ev.context();
String mapKey = fileName.toString();
if (kind == StandardWatchEventKinds.OVERFLOW) {
continue;
} else if (kind == StandardWatchEventKinds.ENTRY_CREATE) {
Path p = dirPath.resolve(fileName);
String mapVal = getFileContents(p);
if(isProgrammaticUpdate(p.toFile())){
fireEvent(new FPMEvent(FPMEvent.EventType.NEW, true, mapKey,mapVal));
}else {
fireEvent(new FPMEvent(FPMEvent.EventType.NEW, false, mapKey, mapVal));
}
} else if (kind == StandardWatchEventKinds.ENTRY_DELETE) {
Path p = dirPath.resolve(fileName);
if(isProgrammaticUpdate(p.toFile())){
fireEvent(new FPMEvent(FPMEvent.EventType.DELETE, true, mapKey, null));
lastModifiedByProgram.remove(p.toFile());
}else {
fireEvent(new FPMEvent(FPMEvent.EventType.DELETE, false, mapKey, null));
}
} else if (kind == StandardWatchEventKinds.ENTRY_MODIFY) {
Path p = dirPath.resolve(fileName);
String mapVal = getFileContents(p);
if(isProgrammaticUpdate(p.toFile())){
fireEvent(new FPMEvent(FPMEvent.EventType.UPDATE, true, mapKey,mapVal));
}else {
fireEvent(new FPMEvent(FPMEvent.EventType.UPDATE, false, mapKey, mapVal));
}
}
}
} catch (InterruptedException e) {
return;
}finally{
if(key!=null)key.reset();
}
}
} catch (IOException e) {
throw new AssertionError(e);
}
}
}
private boolean isProgrammaticUpdate(File file) {
return lastModifiedByProgram.containsKey(file)
&& (file.lastModified() == lastModifiedByProgram.get(file));
}
}
@@ -54,10 +54,11 @@ public abstract class MapStatelessClient<K, V, E extends ParameterizeWireKey>
@Nullable
protected <R> R proxyReturnObject(@NotNull final Class<R> rClass,
@NotNull final E eventId, Object field) {
@NotNull final E eventId,
@NotNull final Object o) {
final long startTime = System.currentTimeMillis();
final long tid = sendEvent(startTime, eventId, out -> writeField(out, field));
final long tid = sendEvent(startTime, eventId, out -> out.object(o));
if (eventReturnsNull(eventId))
return null;
@@ -897,16 +897,13 @@ final class TcpReplicator<K, V> extends AbstractChannelReplicator implements Clo
serverSocket.bind(details.address());
// these can be run on this thread
addPendingRegistration(new Runnable() {
@Override
public void run() {
final Attached attached = new Attached();
attached.connector = ServerConnector.this;
try {
serverChannel.register(TcpReplicator.this.selector, OP_ACCEPT, attached);
} catch (ClosedChannelException e) {
LOG.debug("", e);
}
addPendingRegistration(() -> {
final Attached attached = new Attached();
attached.connector = ServerConnector.this;
try {
serverChannel.register(TcpReplicator.this.selector, OP_ACCEPT, attached);
} catch (ClosedChannelException e) {
LOG.debug("", e);
}
});
@@ -13,22 +13,13 @@ import static org.junit.Assert.*;
* JUnit test class to support {@link FilePerKeyMapTest}
*/
public class FilePerKeyMapTest {
/**
* FilePerMapKey only works with Strings
*/
@Test(expected = AssertionError.class)
public void testWrongType(){
FilePerKeyMap<Integer, String> map = new FilePerKeyMap<>("/tmp/filepermaptests");
map.put(1, "test");
}
/**
* Testing all the methods of the map with simple tests.
*/
@Test
public void testMapMethods() {
//There are no entries in the map so null should be returned
FilePerKeyMap<String, String> map = new FilePerKeyMap<>("/tmp/filepermaptests");
FilePerKeyMap map = new FilePerKeyMap("/tmp/filepermaptests");
//just in case it hasn't been cleared up last time
map.clear();
@@ -117,12 +108,16 @@ public class FilePerKeyMapTest {
} catch (InterruptedException e) {
e.printStackTrace();
}
map.clear();
map.close();
}
@Test
public void perfTest(){
//There are no entries in the map so null should be returned
FilePerKeyMap<String, String> map = new FilePerKeyMap<>("/tmp/filepermaptests");
FilePerKeyMap map = new FilePerKeyMap("/tmp/filepermaptests");
//just in case it hasn't been cleared up last time
map.clear();
@@ -133,8 +128,8 @@ public class FilePerKeyMapTest {
}
String value = sb.toString();
//warmup
for (int i = 0; i < 1000; i++) {
//small warm-up
for (int i = 0; i < 10; i++) {
map.put("big file", value);
}
@@ -145,6 +140,31 @@ public class FilePerKeyMapTest {
map.put("big file", value);
}
System.out.println("Time to update "+ iterations + " iterations " + (System.currentTimeMillis()-time));
map.clear();
map.close();
}
@Test
public void eventTest() {
//There are no entries in the map so null should be returned
FilePerKeyMap map = new FilePerKeyMap("/tmp/filepermaptests");
//just in case it hasn't been cleared up last time
map.clear();
map.registerForEvents(e -> System.out.println(e));
map.put("one", "one");
map.put("one", "one");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
map.clear();
map.close();
}
}