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Fix issue #80: InMemoryStorageEngine simplfication, patch by Dain Sun…
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…dstrom.
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@ijuma
ijuma committed Mar 30, 2009
1 parent 6568b05 commit e88f1dd
Showing 1 changed file with 49 additions and 53 deletions.
102 changes: 49 additions & 53 deletions src/java/voldemort/store/memory/InMemoryStorageEngine.java
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Expand Up @@ -20,6 +20,7 @@
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

Expand All @@ -32,14 +33,14 @@
import voldemort.utils.Utils;
import voldemort.versioning.ObsoleteVersionException;
import voldemort.versioning.Occured;
import voldemort.versioning.VectorClock;
import voldemort.versioning.Version;
import voldemort.versioning.Versioned;

/**
* A simple non-persistent, in-memory store. Useful for unit testing.
*
* @author jay
* @author dain
*
*/
public class InMemoryStorageEngine<K, V> implements StorageEngine<K, V> {
Expand All @@ -60,38 +61,37 @@ public InMemoryStorageEngine(String name, ConcurrentMap<K, List<Versioned<V>>> m
public void close() {}

public boolean delete(K key) {
return map.remove(key) != null;
return delete(key, null);
}

public boolean delete(K key, Version version) {
StoreUtils.assertValidKey(key);

if(version == null)
return delete(key);
return map.remove(key) != null;

List<Versioned<V>> values = map.get(key);
if(values == null) {
return false;
} else {
synchronized(values) {
boolean deletedSomething = false;
Iterator<Versioned<V>> iterator = values.iterator();
while(iterator.hasNext()) {
Versioned<V> item = iterator.next();
if(item.getVersion().compare(version) == Occured.BEFORE) {
iterator.remove();
deletedSomething = true;
}
}
if(values.size() == 0) {
// If this remove fails, then another delete operation got
// there before this one
if(!map.remove(key, values))
return false;
}
synchronized(values) {
boolean deletedSomething = false;
Iterator<Versioned<V>> iterator = values.iterator();
while(iterator.hasNext()) {
Versioned<V> item = iterator.next();
if(item.getVersion().compare(version) == Occured.BEFORE) {
iterator.remove();
deletedSomething = true;
}

return deletedSomething;
}
if(values.size() == 0) {
// If this remove fails, then another delete operation got
// there before this one
if(!map.remove(key, values))
return false;
}

return deletedSomething;
}
}

Expand All @@ -100,10 +100,9 @@ public List<Versioned<V>> get(K key) throws VoldemortException {
List<Versioned<V>> results = map.get(key);
if(results == null) {
return new ArrayList<Versioned<V>>(0);
} else {
synchronized(results) {
return new ArrayList<Versioned<V>>(results);
}
}
synchronized(results) {
return new ArrayList<Versioned<V>>(results);
}
}

Expand All @@ -115,14 +114,14 @@ public Map<K, List<Versioned<V>>> getAll(Iterable<K> keys) throws VoldemortExcep
public void put(K key, Versioned<V> value) throws VoldemortException {
StoreUtils.assertValidKey(key);

VectorClock clock = (VectorClock) value.getVersion();
Version version = value.getVersion();
boolean success = false;
while(!success) {
List<Versioned<V>> items = map.get(key);
// If we have no value, optimistically try to add one
if(items == null) {
items = new ArrayList<Versioned<V>>();
items.add(new Versioned<V>(value.getValue(), clock));
items.add(new Versioned<V>(value.getValue(), version));
success = map.putIfAbsent(key, items) == null;
} else {
synchronized(items) {
Expand Down Expand Up @@ -152,7 +151,7 @@ public void put(K key, Versioned<V> value) throws VoldemortException {
}

public ClosableIterator<Pair<K, Versioned<V>>> entries() {
return new InMemoryIterator();
return new InMemoryIterator<K, V>(map);
}

public String getName() {
Expand All @@ -168,7 +167,7 @@ public String toString(int size) {
StringBuilder builder = new StringBuilder();
builder.append("{");
int count = 0;
for(Map.Entry<K, List<Versioned<V>>> entry: map.entrySet()) {
for(Entry<K, List<Versioned<V>>> entry: map.entrySet()) {
if(count > size) {
builder.append("...");
break;
Expand All @@ -183,54 +182,51 @@ public String toString(int size) {
}

@NotThreadsafe
private class InMemoryIterator implements ClosableIterator<Pair<K, Versioned<V>>> {
private static class InMemoryIterator<K, V> implements ClosableIterator<Pair<K, Versioned<V>>> {

private Iterator<K> iterator;
private final Iterator<Entry<K, List<Versioned<V>>>> iterator;
private K currentKey;
private List<Versioned<V>> currentList;
private int listIndex;
private Iterator<Versioned<V>> currentValues;

public InMemoryIterator() {
this.iterator = map.keySet().iterator();
public InMemoryIterator(ConcurrentMap<K, List<Versioned<V>>> map) {
this.iterator = map.entrySet().iterator();
}

public boolean hasNext() {
return hasNextInCurrentList() || iterator.hasNext();
return hasNextInCurrentValues() || iterator.hasNext();
}

private boolean hasNextInCurrentList() {
return currentList != null && listIndex < currentList.size();
private boolean hasNextInCurrentValues() {
return currentValues != null && currentValues.hasNext();
}

private Pair<K, Versioned<V>> getFromCurrentList() {
Versioned<V> item = currentList.get(listIndex);
listIndex++;
private Pair<K, Versioned<V>> nextInCurrentValues() {
Versioned<V> item = currentValues.next();
return Pair.create(currentKey, item);
}

public Pair<K, Versioned<V>> next() {
if(hasNextInCurrentList()) {
return getFromCurrentList();
if(hasNextInCurrentValues()) {
return nextInCurrentValues();
} else {
// keep trying to get a next, until we find one (they could get
// removed)
while(true) {
K key = null;
List<Versioned<V>> list = null;
do {
key = iterator.next();
list = map.get(key);
} while(list == null);
Entry<K, List<Versioned<V>>> entry = iterator.next();

List<Versioned<V>> list = entry.getValue();
synchronized(list) {
// okay we may have gotten an empty list, if so try
// again
if(list.size() == 0)
continue;
currentKey = key;
currentList = new ArrayList<Versioned<V>>(list);
listIndex = 0;
return getFromCurrentList();

// grab a snapshot of the list while we have exclusive
// access
currentValues = new ArrayList<Versioned<V>>(list).iterator();
}
currentKey = entry.getKey();
return nextInCurrentValues();
}
}
}
Expand Down

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