[ONOS-6342] Refactor transaction architecture to support a shared cache for transactional primitives
Change-Id: I2a17965100895f5aa4d2202028047bb980c11d26
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionalMapParticipant.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionalMapParticipant.java
new file mode 100644
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--- /dev/null
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionalMapParticipant.java
@@ -0,0 +1,233 @@
+/*
+ * Copyright 2017-present 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.primitives.impl;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.base.Objects;
+import com.google.common.base.Throwables;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import org.onosproject.store.primitives.MapUpdate;
+import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.DistributedPrimitive;
+import org.onosproject.store.service.TransactionException;
+import org.onosproject.store.service.TransactionalMap;
+import org.onosproject.store.service.Version;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
+
+/**
+ * Base class for participants within a single {@link TransactionalMap}.
+ * <p>
+ * This class provides the basic functionality required by transactional map participants and provides methods
+ * for defining operations specific to individual isolation levels.
+ *
+ * @param <K> key type
+ * @param <V> value type.
+ */
+public abstract class TransactionalMapParticipant<K, V> implements TransactionalMap<K, V>, TransactionParticipant {
+ private static final String TX_CLOSED_ERROR = "Transaction is closed";
+ private static final String ERROR_NULL_VALUE = "Null values are not allowed";
+ private static final String ERROR_NULL_KEY = "Null key is not allowed";
+
+ protected final ConsistentMap<K, V> backingMap;
+ protected final Transaction<MapUpdate<K, V>> transaction;
+ protected final Map<K, V> writeCache = Maps.newConcurrentMap();
+ protected final Set<K> deleteSet = Sets.newConcurrentHashSet();
+ protected final List<MapUpdate<K, V>> log = new ArrayList<>();
+ protected volatile Version lock;
+
+ protected TransactionalMapParticipant(
+ ConsistentMap<K, V> backingMap,
+ Transaction<MapUpdate<K, V>> transaction) {
+ this.backingMap = backingMap;
+ this.transaction = transaction;
+ }
+
+ /**
+ * Starts the transaction for this partition when a read occurs.
+ * <p>
+ * Acquiring a pessimistic lock at the start of the transaction ensures that underlying cached maps have been
+ * synchronized prior to a read.
+ */
+ private void beginTransaction() {
+ if (!transaction.isOpen()) {
+ try {
+ lock = transaction.begin()
+ .get(DistributedPrimitive.DEFAULT_OPERTATION_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ throw new TransactionException.Interrupted();
+ } catch (TimeoutException e) {
+ throw new TransactionException.Timeout();
+ } catch (ExecutionException e) {
+ Throwables.propagateIfPossible(e.getCause());
+ throw new TransactionException(e.getCause());
+ }
+ }
+ }
+
+ @Override
+ public V get(K key) {
+ // Start the transaction for this primitive/partition if necessary.
+ beginTransaction();
+
+ checkState(transaction.isOpen(), TX_CLOSED_ERROR);
+ checkNotNull(key, ERROR_NULL_KEY);
+
+ if (deleteSet.contains(key)) {
+ return null;
+ }
+
+ V latest = writeCache.get(key);
+ if (latest != null) {
+ return latest;
+ } else {
+ return read(key);
+ }
+ }
+
+ /**
+ * Executes a get operation based on the transaction isolation level.
+ *
+ * @param key the key to look up
+ * @return the value
+ */
+ protected abstract V read(K key);
+
+ @Override
+ public boolean containsKey(K key) {
+ return get(key) != null;
+ }
+
+ @Override
+ public V put(K key, V value) {
+ checkNotNull(value, ERROR_NULL_VALUE);
+
+ V latest = get(key);
+ writeCache.put(key, value);
+ deleteSet.remove(key);
+ return latest;
+ }
+
+ @Override
+ public V remove(K key) {
+ V latest = get(key);
+ if (latest != null) {
+ writeCache.remove(key);
+ deleteSet.add(key);
+ }
+ return latest;
+ }
+
+ @Override
+ public boolean remove(K key, V value) {
+ checkNotNull(value, ERROR_NULL_VALUE);
+
+ V latest = get(key);
+ if (Objects.equal(value, latest)) {
+ remove(key);
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public boolean replace(K key, V oldValue, V newValue) {
+ checkNotNull(oldValue, ERROR_NULL_VALUE);
+ checkNotNull(newValue, ERROR_NULL_VALUE);
+
+ V latest = get(key);
+ if (Objects.equal(oldValue, latest)) {
+ put(key, newValue);
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public V putIfAbsent(K key, V value) {
+ checkNotNull(value, ERROR_NULL_VALUE);
+
+ V latest = get(key);
+ if (latest == null) {
+ put(key, value);
+ }
+ return latest;
+ }
+
+ @Override
+ public boolean hasPendingUpdates() {
+ return records().findAny().isPresent();
+ }
+
+ @Override
+ public CompletableFuture<Boolean> prepare() {
+ return transaction.prepare(log());
+ }
+
+ @Override
+ public CompletableFuture<Void> commit() {
+ return transaction.commit();
+ }
+
+ @Override
+ public CompletableFuture<Boolean> prepareAndCommit() {
+ return transaction.prepareAndCommit(log());
+ }
+
+ @Override
+ public CompletableFuture<Void> rollback() {
+ return transaction.rollback();
+ }
+
+ /**
+ * Returns a list of updates performed within this map partition.
+ *
+ * @return a list of map updates
+ */
+ protected List<MapUpdate<K, V>> log() {
+ return records().collect(Collectors.toList());
+ }
+
+ /**
+ * Returns a stream of updates performed within this map partition.
+ *
+ * @return a stream of map updates
+ */
+ protected abstract Stream<MapUpdate<K, V>> records();
+
+ @Override
+ public String toString() {
+ return MoreObjects.toStringHelper(this)
+ .add("backingMap", backingMap)
+ .add("updates", log())
+ .toString();
+ }
+}
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