WIP: Revamped transaction API. Introduces a transaction context for running blocks of code that can be committed
atomically.
Change-Id: I6ba21050a2644a42f3c073fa04ff776ef2c5ff4c
diff --git a/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java b/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
index a375fe0..e0ed4bc 100644
--- a/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
+++ b/core/api/src/main/java/org/onosproject/store/service/ConsistentMap.java
@@ -17,7 +17,6 @@
package org.onosproject.store.service;
import java.util.Collection;
-import java.util.List;
import java.util.Set;
import java.util.Map.Entry;
@@ -37,13 +36,6 @@
* concurrency by allowing conditional updates that take into consideration
* the version or value that was previously read.
* </p><p>
- * The map also supports atomic batch updates (transactions). One can provide a list
- * of updates to be applied atomically if and only if all the operations are guaranteed
- * to succeed i.e. all their preconditions are met. For example, the precondition
- * for a putIfAbsent API call is absence of a mapping for the key. Similarly, the
- * precondition for a conditional replace operation is the presence of an expected
- * version or value
- * </p><p>
* This map does not allow null values. All methods can throw a ConsistentMapException
* (which extends RuntimeException) to indicate failures.
*
@@ -202,15 +194,4 @@
* @return true if the value was replaced
*/
boolean replace(K key, long oldVersion, V newValue);
-
- /**
- * Atomically apply the specified list of updates to the map.
- * If any of the updates cannot be applied due to a precondition
- * violation, none of the updates will be applied and the state of
- * the map remains unaltered.
- *
- * @param updates list of updates to apply atomically.
- * @return true if the map was updated.
- */
- boolean batchUpdate(List<UpdateOperation<K, V>> updates);
}
diff --git a/core/api/src/main/java/org/onosproject/store/service/StorageService.java b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
index 32512c8..c99b7b8 100644
--- a/core/api/src/main/java/org/onosproject/store/service/StorageService.java
+++ b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
@@ -39,5 +39,9 @@
*/
<K, V> ConsistentMap<K , V> createConsistentMap(String name, Serializer serializer);
- // TODO: add API for creating Eventually Consistent Map.
+ /**
+ * Creates a new transaction context.
+ * @return transaction context
+ */
+ TransactionContext createTransactionContext();
}
\ No newline at end of file
diff --git a/core/api/src/main/java/org/onosproject/store/service/TransactionContext.java b/core/api/src/main/java/org/onosproject/store/service/TransactionContext.java
new file mode 100644
index 0000000..4fbeeeb
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/TransactionContext.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.service;
+
+/**
+ * Provides a context for transactional operations.
+ * <p>
+ * A transaction context provides a boundary within which transactions
+ * are run. It also is a place where all modifications made within a transaction
+ * are cached until the point when the transaction commits or aborts. It thus ensures
+ * isolation of work happening with in the transaction boundary.
+ * <p>
+ * A transaction context is a vehicle for grouping operations into a unit with the
+ * properties of atomicity, isolation, and durability. Transactions also provide the
+ * ability to maintain an application's invariants or integrity constraints,
+ * supporting the property of consistency. Together these properties are known as ACID.
+ */
+public interface TransactionContext {
+
+ /**
+ * Returns if this transaction context is open.
+ * @return true if open, false otherwise.
+ */
+ boolean isOpen();
+
+ /**
+ * Starts a new transaction.
+ */
+ void begin();
+
+ /**
+ * Commits a transaction that was previously started thereby making its changes permanent
+ * and externally visible.
+ * @throws TransactionException if transaction fails to commit.
+ */
+ void commit();
+
+ /**
+ * Rolls back the current transaction, discarding all its changes.
+ */
+ void rollback();
+
+ /**
+ * Creates a new transactional map.
+ * @param mapName name of the transactional map.
+ * @param serializer serializer to use for encoding/decoding keys and vaulues.
+ * @return new Transactional Map.
+ */
+ <K, V> TransactionalMap<K, V> createTransactionalMap(String mapName, Serializer serializer);
+}
\ No newline at end of file
diff --git a/core/api/src/main/java/org/onosproject/store/service/TransactionException.java b/core/api/src/main/java/org/onosproject/store/service/TransactionException.java
new file mode 100644
index 0000000..8261fbd
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/TransactionException.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.service;
+
+/**
+ * Top level exception for Transaction failures.
+ */
+@SuppressWarnings("serial")
+public class TransactionException extends RuntimeException {
+ public TransactionException() {
+ }
+
+ public TransactionException(Throwable t) {
+ super(t);
+ }
+
+ /**
+ * Transaction timeout.
+ */
+ public static class Timeout extends TransactionException {
+ }
+
+ /**
+ * Transaction interrupted.
+ */
+ public static class Interrupted extends TransactionException {
+ }
+
+ /**
+ * Transaction failure due to optimistic concurrency failure.
+ */
+ public static class OptimisticConcurrencyFailure extends TransactionException {
+ }
+}
\ No newline at end of file
diff --git a/core/api/src/main/java/org/onosproject/store/service/TransactionalMap.java b/core/api/src/main/java/org/onosproject/store/service/TransactionalMap.java
new file mode 100644
index 0000000..c59600c
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/service/TransactionalMap.java
@@ -0,0 +1,166 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.service;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.Map.Entry;
+
+/**
+ * Transactional Map data structure.
+ * <p>
+ * A TransactionalMap is created by invoking {@link TransactionContext#createTransactionalMap createTransactionalMap}
+ * method. All operations performed on this map with in a transaction boundary are invisible externally
+ * until the point when the transaction commits. A commit usually succeeds in the absence of conflicts.
+ *
+ * @param <K> type of key.
+ * @param <V> type of value.
+ */
+public interface TransactionalMap<K, V> {
+
+ /**
+ * Returns the number of entries in the map.
+ *
+ * @return map size.
+ */
+ int size();
+
+ /**
+ * Returns true if the map is empty.
+ *
+ * @return true if map has no entries, false otherwise.
+ */
+ boolean isEmpty();
+
+ /**
+ * Returns true if this map contains a mapping for the specified key.
+ *
+ * @param key key
+ * @return true if map contains key, false otherwise.
+ */
+ boolean containsKey(K key);
+
+ /**
+ * Returns true if this map contains the specified value.
+ *
+ * @param value value
+ * @return true if map contains value, false otherwise.
+ */
+ boolean containsValue(V value);
+
+ /**
+ * Returns the value to which the specified key is mapped, or null if this
+ * map contains no mapping for the key.
+ *
+ * @param key the key whose associated value is to be returned
+ * @return the value to which the specified key is mapped, or null if
+ * this map contains no mapping for the key
+ */
+ V get(K key);
+
+ /**
+ * Associates the specified value with the specified key in this map (optional operation).
+ * If the map previously contained a mapping for the key, the old value is replaced by the
+ * specified value.
+ *
+ * @param key key with which the specified value is to be associated
+ * @param value value to be associated with the specified key
+ * @return the previous value associated with key, or null if there was
+ * no mapping for key.
+ */
+ V put(K key, V value);
+
+ /**
+ * Removes the mapping for a key from this map if it is present (optional operation).
+ *
+ * @param key key whose value is to be removed from the map
+ * @return the value to which this map previously associated the key,
+ * or null if the map contained no mapping for the key.
+ */
+ V remove(K key);
+
+ /**
+ * Removes all of the mappings from this map (optional operation).
+ * The map will be empty after this call returns.
+ */
+ void clear();
+
+ /**
+ * Returns a Set view of the keys contained in this map.
+ * This method differs from the behavior of java.util.Map.keySet() in that
+ * what is returned is a unmodifiable snapshot view of the keys in the ConsistentMap.
+ * Attempts to modify the returned set, whether direct or via its iterator,
+ * result in an UnsupportedOperationException.
+ *
+ * @return a set of the keys contained in this map
+ */
+ Set<K> keySet();
+
+ /**
+ * Returns the collection of values contained in this map.
+ * This method differs from the behavior of java.util.Map.values() in that
+ * what is returned is a unmodifiable snapshot view of the values in the ConsistentMap.
+ * Attempts to modify the returned collection, whether direct or via its iterator,
+ * result in an UnsupportedOperationException.
+ *
+ * @return a collection of the values contained in this map
+ */
+ Collection<V> values();
+
+ /**
+ * Returns the set of entries contained in this map.
+ * This method differs from the behavior of java.util.Map.entrySet() in that
+ * what is returned is a unmodifiable snapshot view of the entries in the ConsistentMap.
+ * Attempts to modify the returned set, whether direct or via its iterator,
+ * result in an UnsupportedOperationException.
+ *
+ * @return set of entries contained in this map.
+ */
+ Set<Entry<K, V>> entrySet();
+
+ /**
+ * If the specified key is not already associated with a value
+ * associates it with the given value and returns null, else returns the current value.
+ *
+ * @param key key with which the specified value is to be associated
+ * @param value value to be associated with the specified key
+ * @return the previous value associated with the specified key or null
+ * if key does not already mapped to a value.
+ */
+ V putIfAbsent(K key, V value);
+
+ /**
+ * Removes the entry for the specified key only if it is currently
+ * mapped to the specified value.
+ *
+ * @param key key with which the specified value is associated
+ * @param value value expected to be associated with the specified key
+ * @return true if the value was removed
+ */
+ boolean remove(K key, V value);
+
+ /**
+ * Replaces the entry for the specified key only if currently mapped
+ * to the specified value.
+ *
+ * @param key key with which the specified value is associated
+ * @param oldValue value expected to be associated with the specified key
+ * @param newValue value to be associated with the specified key
+ * @return true if the value was replaced
+ */
+ boolean replace(K key, V oldValue, V newValue);
+}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/ConsistentMapImpl.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/ConsistentMapImpl.java
index eb18071..a5b6656 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/ConsistentMapImpl.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/ConsistentMapImpl.java
@@ -20,7 +20,6 @@
import java.util.Collection;
import java.util.Collections;
-import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.CompletableFuture;
@@ -35,7 +34,6 @@
import org.onosproject.store.service.ConsistentMap;
import org.onosproject.store.service.ConsistentMapException;
import org.onosproject.store.service.Serializer;
-import org.onosproject.store.service.UpdateOperation;
import org.onosproject.store.service.Versioned;
import com.google.common.cache.CacheBuilder;
@@ -73,7 +71,7 @@
return serializer.decode(HexString.fromHexString(key));
}
- ConsistentMapImpl(String name,
+ public ConsistentMapImpl(String name,
DatabaseProxy<String, byte[]> proxy,
Serializer serializer) {
this.name = checkNotNull(name, "map name cannot be null");
@@ -196,15 +194,6 @@
return complete(proxy.replace(name, keyCache.getUnchecked(key), oldVersion, serializer.encode(newValue)));
}
- @Override
- public boolean batchUpdate(List<UpdateOperation<K, V>> updates) {
- checkNotNull(updates, "updates cannot be null");
- return complete(proxy.atomicBatchUpdate(updates
- .stream()
- .map(this::toRawUpdateOperation)
- .collect(Collectors.toList())));
- }
-
private static <T> T complete(CompletableFuture<T> future) {
try {
return future.get(OPERATION_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
@@ -225,31 +214,4 @@
serializer.decode(e.getValue().value()),
e.getValue().version()));
}
-
- private UpdateOperation<String, byte[]> toRawUpdateOperation(UpdateOperation<K, V> update) {
-
- checkArgument(name.equals(update.tableName()), "Unexpected table name");
-
- UpdateOperation.Builder<String, byte[]> rawUpdate = UpdateOperation.<String, byte[]>newBuilder();
-
- rawUpdate = rawUpdate.withKey(keyCache.getUnchecked(update.key()))
- .withCurrentVersion(update.currentVersion())
- .withType(update.type());
-
- rawUpdate = rawUpdate.withTableName(update.tableName());
-
- if (update.value() != null) {
- rawUpdate = rawUpdate.withValue(serializer.encode(update.value()));
- } else {
- checkState(update.type() == UpdateOperation.Type.REMOVE
- || update.type() == UpdateOperation.Type.REMOVE_IF_VERSION_MATCH,
- ERROR_NULL_VALUE);
- }
-
- if (update.currentValue() != null) {
- rawUpdate = rawUpdate.withCurrentValue(serializer.encode(update.currentValue()));
- }
-
- return rawUpdate.build();
- }
}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DatabaseManager.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DatabaseManager.java
index 28a9c5a..2df9b4c 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DatabaseManager.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DatabaseManager.java
@@ -41,6 +41,7 @@
import org.onosproject.store.service.ConsistentMap;
import org.onosproject.store.service.Serializer;
import org.onosproject.store.service.StorageService;
+import org.onosproject.store.service.TransactionContext;
import org.slf4j.Logger;
import com.google.common.collect.Sets;
@@ -154,4 +155,9 @@
public <K, V> ConsistentMap<K , V> createConsistentMap(String name, Serializer serializer) {
return new ConsistentMapImpl<K, V>(name, partitionedDatabase, serializer);
}
+
+ @Override
+ public TransactionContext createTransactionContext() {
+ return new DefaultTransactionContext(partitionedDatabase);
+ }
}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionContext.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionContext.java
new file mode 100644
index 0000000..5103348
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionContext.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.consistent.impl;
+
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import static com.google.common.base.Preconditions.*;
+
+import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.TransactionContext;
+import org.onosproject.store.service.TransactionException;
+import org.onosproject.store.service.TransactionalMap;
+import org.onosproject.store.service.UpdateOperation;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+
+/**
+ * Default TransactionContext implementation.
+ */
+public class DefaultTransactionContext implements TransactionContext {
+
+ private final Map<String, DefaultTransactionalMap> txMaps = Maps.newHashMap();
+ private boolean isOpen = false;
+ DatabaseProxy<String, byte[]> databaseProxy;
+ private static final String TX_NOT_OPEN_ERROR = "Transaction is not open";
+ private static final int TRANSACTION_TIMEOUT_MILLIS = 2000;
+
+ DefaultTransactionContext(DatabaseProxy<String, byte[]> proxy) {
+ this.databaseProxy = proxy;
+ }
+
+ @Override
+ public void begin() {
+ isOpen = true;
+ }
+
+ @Override
+ public <K, V> TransactionalMap<K, V> createTransactionalMap(String mapName,
+ Serializer serializer) {
+ checkNotNull(mapName, "map name is null");
+ checkNotNull(serializer, "serializer is null");
+ checkState(isOpen, TX_NOT_OPEN_ERROR);
+ if (!txMaps.containsKey(mapName)) {
+ ConsistentMap<K, V> backingMap = new ConsistentMapImpl<>(mapName, databaseProxy, serializer);
+ DefaultTransactionalMap<K, V> txMap = new DefaultTransactionalMap<>(mapName, backingMap, this, serializer);
+ txMaps.put(mapName, txMap);
+ }
+ return txMaps.get(mapName);
+ }
+
+ @Override
+ public void commit() {
+ checkState(isOpen, TX_NOT_OPEN_ERROR);
+ List<UpdateOperation<String, byte[]>> allUpdates =
+ Lists.newLinkedList();
+ try {
+ txMaps.values()
+ .stream()
+ .forEach(m -> {
+ allUpdates.addAll(m.prepareDatabaseUpdates());
+ });
+
+ if (!complete(databaseProxy.atomicBatchUpdate(allUpdates))) {
+ throw new TransactionException.OptimisticConcurrencyFailure();
+ }
+ } finally {
+ isOpen = false;
+ }
+ }
+
+ @Override
+ public void rollback() {
+ checkState(isOpen, TX_NOT_OPEN_ERROR);
+ txMaps.values()
+ .stream()
+ .forEach(m -> m.rollback());
+ }
+
+ @Override
+ public boolean isOpen() {
+ return false;
+ }
+
+ private static <T> T complete(CompletableFuture<T> future) {
+ try {
+ return future.get(TRANSACTION_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ throw new TransactionException.Interrupted();
+ } catch (TimeoutException e) {
+ throw new TransactionException.Timeout();
+ } catch (ExecutionException e) {
+ throw new TransactionException(e.getCause());
+ }
+ }
+}
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalMap.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalMap.java
new file mode 100644
index 0000000..c98c336
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultTransactionalMap.java
@@ -0,0 +1,243 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.consistent.impl;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+import java.util.Set;
+
+import org.onlab.util.HexString;
+import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.TransactionContext;
+import org.onosproject.store.service.TransactionalMap;
+import org.onosproject.store.service.UpdateOperation;
+import org.onosproject.store.service.Versioned;
+
+import static com.google.common.base.Preconditions.*;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+
+/**
+ * Default Transactional Map implementation that provides a repeatable reads
+ * transaction isolation level.
+ *
+ * @param <K> key type
+ * @param <V> value type.
+ */
+public class DefaultTransactionalMap<K, V> implements TransactionalMap<K, V> {
+
+ private final TransactionContext txContext;
+ private static final String TX_CLOSED_ERROR = "Transaction is closed";
+ private final ConsistentMap<K, V> backingMap;
+ private final String name;
+ private final Serializer serializer;
+ private final Map<K, Versioned<V>> readCache = Maps.newConcurrentMap();
+ private final Map<K, V> writeCache = Maps.newConcurrentMap();
+ private final Set<K> deleteSet = Sets.newConcurrentHashSet();
+
+ public DefaultTransactionalMap(
+ String name,
+ ConsistentMap<K, V> backingMap,
+ TransactionContext txContext,
+ Serializer serializer) {
+ this.name = name;
+ this.backingMap = backingMap;
+ this.txContext = txContext;
+ this.serializer = serializer;
+ }
+
+ @Override
+ public V get(K key) {
+ checkState(txContext.isOpen(), TX_CLOSED_ERROR);
+ if (deleteSet.contains(key)) {
+ return null;
+ } else if (writeCache.containsKey(key)) {
+ return writeCache.get(key);
+ } else {
+ if (!readCache.containsKey(key)) {
+ readCache.put(key, backingMap.get(key));
+ }
+ Versioned<V> v = readCache.get(key);
+ return v != null ? v.value() : null;
+ }
+ }
+
+ @Override
+ public V put(K key, V value) {
+ checkState(txContext.isOpen(), TX_CLOSED_ERROR);
+ Versioned<V> original = readCache.get(key);
+ V recentUpdate = writeCache.put(key, value);
+ deleteSet.remove(key);
+ return recentUpdate == null ? (original != null ? original.value() : null) : recentUpdate;
+ }
+
+ @Override
+ public V remove(K key) {
+ checkState(txContext.isOpen(), TX_CLOSED_ERROR);
+ Versioned<V> original = readCache.get(key);
+ V recentUpdate = writeCache.remove(key);
+ deleteSet.add(key);
+ return recentUpdate == null ? (original != null ? original.value() : null) : recentUpdate;
+ }
+
+ @Override
+ public boolean remove(K key, V value) {
+ V currentValue = get(key);
+ if (value.equals(currentValue)) {
+ remove(key);
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public boolean replace(K key, V oldValue, V newValue) {
+ V currentValue = get(key);
+ if (oldValue.equals(currentValue)) {
+ put(key, newValue);
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public int size() {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public boolean isEmpty() {
+ return size() == 0;
+ }
+
+ @Override
+ public boolean containsKey(K key) {
+ return get(key) != null;
+ }
+
+ @Override
+ public boolean containsValue(V value) {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public void clear() {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Set<K> keySet() {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Collection<V> values() {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public Set<Entry<K, V>> entrySet() {
+ // TODO
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public V putIfAbsent(K key, V value) {
+ V currentValue = get(key);
+ if (currentValue == null) {
+ put(key, value);
+ return null;
+ }
+ return currentValue;
+ }
+
+ protected List<UpdateOperation<String, byte[]>> prepareDatabaseUpdates() {
+ List<UpdateOperation<K, V>> updates = Lists.newLinkedList();
+ deleteSet.forEach(key -> {
+ Versioned<V> original = readCache.get(key);
+ if (original != null) {
+ updates.add(UpdateOperation.<K, V>newBuilder()
+ .withTableName(name)
+ .withType(UpdateOperation.Type.REMOVE_IF_VERSION_MATCH)
+ .withKey(key)
+ .withCurrentVersion(original.version())
+ .build());
+ }
+ });
+ writeCache.forEach((key, value) -> {
+ Versioned<V> original = readCache.get(key);
+ if (original == null) {
+ updates.add(UpdateOperation.<K, V>newBuilder()
+ .withTableName(name)
+ .withType(UpdateOperation.Type.PUT_IF_ABSENT)
+ .withKey(key)
+ .withValue(value)
+ .build());
+ } else {
+ updates.add(UpdateOperation.<K, V>newBuilder()
+ .withTableName(name)
+ .withType(UpdateOperation.Type.PUT_IF_VERSION_MATCH)
+ .withKey(key)
+ .withCurrentVersion(original.version())
+ .withValue(value)
+ .build());
+ }
+ });
+ return updates.stream().map(this::toRawUpdateOperation).collect(Collectors.toList());
+ }
+
+ private UpdateOperation<String, byte[]> toRawUpdateOperation(UpdateOperation<K, V> update) {
+
+ UpdateOperation.Builder<String, byte[]> rawUpdate = UpdateOperation.<String, byte[]>newBuilder();
+
+ rawUpdate = rawUpdate.withKey(HexString.toHexString(serializer.encode(update.key())))
+ .withCurrentVersion(update.currentVersion())
+ .withType(update.type());
+
+ rawUpdate = rawUpdate.withTableName(update.tableName());
+
+ if (update.value() != null) {
+ rawUpdate = rawUpdate.withValue(serializer.encode(update.value()));
+ }
+
+ if (update.currentValue() != null) {
+ rawUpdate = rawUpdate.withCurrentValue(serializer.encode(update.currentValue()));
+ }
+
+ return rawUpdate.build();
+ }
+
+ /**
+ * Discards all changes made to this transactional map.
+ */
+ protected void rollback() {
+ readCache.clear();
+ writeCache.clear();
+ deleteSet.clear();
+ }
+}
\ No newline at end of file