Java tutorial
/* * 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 com.google.common.cache.CacheBuilder; import com.google.common.cache.CacheLoader; import com.google.common.cache.LoadingCache; import com.google.common.collect.Maps; import org.onlab.util.HexString; import org.onlab.util.SharedExecutors; import org.onlab.util.Tools; import org.onosproject.core.ApplicationId; import org.onosproject.store.service.AsyncConsistentMap; import org.onosproject.store.service.ConsistentMapException; import org.onosproject.store.service.MapEvent; import org.onosproject.store.service.MapEventListener; import org.onosproject.store.service.Serializer; import org.onosproject.store.service.Versioned; import org.slf4j.Logger; import java.util.Collection; import java.util.Map; import java.util.Map.Entry; import java.util.Objects; import java.util.Set; import java.util.concurrent.CompletableFuture; import java.util.concurrent.CopyOnWriteArraySet; import java.util.concurrent.atomic.AtomicReference; import java.util.function.BiFunction; import java.util.function.Function; import java.util.function.Predicate; import java.util.stream.Collectors; import static com.google.common.base.Preconditions.checkNotNull; import static org.onosproject.store.consistent.impl.StateMachineUpdate.Target.MAP_UPDATE; import static org.onosproject.store.consistent.impl.StateMachineUpdate.Target.TX_COMMIT; import static org.slf4j.LoggerFactory.getLogger; /** * AsyncConsistentMap implementation that is backed by a Raft consensus * based database. * * @param <K> type of key. * @param <V> type of value. */ public class DefaultAsyncConsistentMap<K, V> implements AsyncConsistentMap<K, V> { private final String name; private final ApplicationId applicationId; private final Database database; private final Serializer serializer; private final boolean readOnly; private final boolean purgeOnUninstall; private static final String PRIMITIVE_NAME = "consistentMap"; private static final String SIZE = "size"; private static final String IS_EMPTY = "isEmpty"; private static final String CONTAINS_KEY = "containsKey"; private static final String CONTAINS_VALUE = "containsValue"; private static final String GET = "get"; private static final String COMPUTE_IF = "computeIf"; private static final String PUT = "put"; private static final String PUT_AND_GET = "putAndGet"; private static final String PUT_IF_ABSENT = "putIfAbsent"; private static final String REMOVE = "remove"; private static final String CLEAR = "clear"; private static final String KEY_SET = "keySet"; private static final String VALUES = "values"; private static final String ENTRY_SET = "entrySet"; private static final String REPLACE = "replace"; private static final String COMPUTE_IF_ABSENT = "computeIfAbsent"; private final Set<MapEventListener<K, V>> listeners = new CopyOnWriteArraySet<>(); private final Logger log = getLogger(getClass()); private final MeteringAgent monitor; private static final String ERROR_NULL_KEY = "Key cannot be null"; private static final String ERROR_NULL_VALUE = "Null values are not allowed"; private final LoadingCache<K, String> keyCache = CacheBuilder.newBuilder().softValues() .build(new CacheLoader<K, String>() { @Override public String load(K key) { return HexString.toHexString(serializer.encode(key)); } }); protected K dK(String key) { return serializer.decode(HexString.fromHexString(key)); } public DefaultAsyncConsistentMap(String name, ApplicationId applicationId, Database database, Serializer serializer, boolean readOnly, boolean purgeOnUninstall, boolean meteringEnabled) { this.name = checkNotNull(name, "map name cannot be null"); this.applicationId = applicationId; this.database = checkNotNull(database, "database cannot be null"); this.serializer = checkNotNull(serializer, "serializer cannot be null"); this.readOnly = readOnly; this.purgeOnUninstall = purgeOnUninstall; this.database.registerConsumer(update -> { SharedExecutors.getSingleThreadExecutor().execute(() -> { if (listeners.isEmpty()) { return; } try { if (update.target() == MAP_UPDATE) { Result<UpdateResult<String, byte[]>> result = update.output(); if (result.success() && result.value().mapName().equals(name)) { MapEvent<K, V> mapEvent = result.value() .<K, V>map(this::dK, v -> serializer.decode(Tools.copyOf(v))).toMapEvent(); notifyListeners(mapEvent); } } else if (update.target() == TX_COMMIT) { CommitResponse response = update.output(); if (response.success()) { response.updates().forEach(u -> { if (u.mapName().equals(name)) { MapEvent<K, V> mapEvent = u .<K, V>map(this::dK, v -> serializer.decode(Tools.copyOf(v))) .toMapEvent(); notifyListeners(mapEvent); } }); } } } catch (Exception e) { log.warn("Error notifying listeners", e); } }); }); this.monitor = new MeteringAgent(PRIMITIVE_NAME, name, meteringEnabled); } /** * Returns this map name. * @return map name */ public String name() { return name; } /** * Returns the serializer for map entries. * @return map entry serializer */ public Serializer serializer() { return serializer; } /** * Returns the applicationId owning this map. * @return application Id */ public ApplicationId applicationId() { return applicationId; } /** * Returns whether the map entries should be purged when the application * owning it is uninstalled. * @return true is map needs to cleared on app uninstall; false otherwise */ public boolean purgeOnUninstall() { return purgeOnUninstall; } @Override public CompletableFuture<Integer> size() { final MeteringAgent.Context timer = monitor.startTimer(SIZE); return database.mapSize(name).whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Boolean> isEmpty() { final MeteringAgent.Context timer = monitor.startTimer(IS_EMPTY); return database.mapIsEmpty(name).whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Boolean> containsKey(K key) { checkNotNull(key, ERROR_NULL_KEY); final MeteringAgent.Context timer = monitor.startTimer(CONTAINS_KEY); return database.mapContainsKey(name, keyCache.getUnchecked(key)).whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Boolean> containsValue(V value) { checkNotNull(value, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(CONTAINS_VALUE); return database.mapContainsValue(name, serializer.encode(value)).whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Versioned<V>> get(K key) { checkNotNull(key, ERROR_NULL_KEY); final MeteringAgent.Context timer = monitor.startTimer(GET); return database.mapGet(name, keyCache.getUnchecked(key)).whenComplete((r, e) -> timer.stop(e)) .thenApply(v -> v != null ? v.map(serializer::decode) : null); } @Override public CompletableFuture<Versioned<V>> computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(mappingFunction, "Mapping function cannot be null"); final MeteringAgent.Context timer = monitor.startTimer(COMPUTE_IF_ABSENT); return updateAndGet(key, Match.ifNull(), Match.any(), mappingFunction.apply(key)) .whenComplete((r, e) -> timer.stop(e)).thenApply(v -> v.newValue()); } @Override public CompletableFuture<Versioned<V>> computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { return computeIf(key, Objects::nonNull, remappingFunction); } @Override public CompletableFuture<Versioned<V>> compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { return computeIf(key, v -> true, remappingFunction); } @Override public CompletableFuture<Versioned<V>> computeIf(K key, Predicate<? super V> condition, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(condition, "predicate function cannot be null"); checkNotNull(remappingFunction, "Remapping function cannot be null"); final MeteringAgent.Context timer = monitor.startTimer(COMPUTE_IF); return get(key).thenCompose(r1 -> { V existingValue = r1 == null ? null : r1.value(); // if the condition evaluates to false, return existing value. if (!condition.test(existingValue)) { return CompletableFuture.completedFuture(r1); } AtomicReference<V> computedValue = new AtomicReference<>(); // if remappingFunction throws an exception, return the exception. try { computedValue.set(remappingFunction.apply(key, existingValue)); } catch (Exception e) { return Tools.exceptionalFuture(e); } if (computedValue.get() == null && r1 == null) { return CompletableFuture.completedFuture(null); } Match<V> valueMatcher = r1 == null ? Match.ifNull() : Match.any(); Match<Long> versionMatcher = r1 == null ? Match.any() : Match.ifValue(r1.version()); return updateAndGet(key, valueMatcher, versionMatcher, computedValue.get()) .whenComplete((r, e) -> timer.stop(e)).thenApply(v -> { if (v.updated()) { return v.newValue(); } else { throw new ConsistentMapException.ConcurrentModification(); } }); }); } @Override public CompletableFuture<Versioned<V>> put(K key, V value) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(value, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(PUT); return updateAndGet(key, Match.any(), Match.any(), value).thenApply(v -> v.oldValue()) .whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Versioned<V>> putAndGet(K key, V value) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(value, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(PUT_AND_GET); return updateAndGet(key, Match.any(), Match.any(), value).thenApply(v -> v.newValue()) .whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Versioned<V>> remove(K key) { checkNotNull(key, ERROR_NULL_KEY); final MeteringAgent.Context timer = monitor.startTimer(REMOVE); return updateAndGet(key, Match.any(), Match.any(), null).thenApply(v -> v.oldValue()) .whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Void> clear() { checkIfUnmodifiable(); final MeteringAgent.Context timer = monitor.startTimer(CLEAR); return database.mapClear(name).thenApply(this::unwrapResult).whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Set<K>> keySet() { final MeteringAgent.Context timer = monitor.startTimer(KEY_SET); return database.mapKeySet(name).thenApply(s -> s.stream().map(this::dK).collect(Collectors.toSet())) .whenComplete((r, e) -> timer.stop(e)); } @Override public CompletableFuture<Collection<Versioned<V>>> values() { final MeteringAgent.Context timer = monitor.startTimer(VALUES); return database.mapValues(name).whenComplete((r, e) -> timer.stop(e)) .thenApply(c -> c.stream().map(v -> v.<V>map(serializer::decode)).collect(Collectors.toList())); } @Override public CompletableFuture<Set<Entry<K, Versioned<V>>>> entrySet() { final MeteringAgent.Context timer = monitor.startTimer(ENTRY_SET); return database.mapEntrySet(name).whenComplete((r, e) -> timer.stop(e)) .thenApply(s -> s.stream().map(this::mapRawEntry).collect(Collectors.toSet())); } @Override public CompletableFuture<Versioned<V>> putIfAbsent(K key, V value) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(value, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(PUT_IF_ABSENT); return updateAndGet(key, Match.ifNull(), Match.any(), value).whenComplete((r, e) -> timer.stop(e)) .thenApply(v -> v.oldValue()); } @Override public CompletableFuture<Boolean> remove(K key, V value) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(value, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(REMOVE); return updateAndGet(key, Match.ifValue(value), Match.any(), null).whenComplete((r, e) -> timer.stop(e)) .thenApply(v -> v.updated()); } @Override public CompletableFuture<Boolean> remove(K key, long version) { checkNotNull(key, ERROR_NULL_KEY); final MeteringAgent.Context timer = monitor.startTimer(REMOVE); return updateAndGet(key, Match.any(), Match.ifValue(version), null).whenComplete((r, e) -> timer.stop(e)) .thenApply(v -> v.updated()); } @Override public CompletableFuture<Boolean> replace(K key, V oldValue, V newValue) { checkNotNull(key, ERROR_NULL_KEY); checkNotNull(oldValue, ERROR_NULL_VALUE); checkNotNull(newValue, ERROR_NULL_VALUE); final MeteringAgent.Context timer = monitor.startTimer(REPLACE); return updateAndGet(key, Match.ifValue(oldValue), Match.any(), newValue) .whenComplete((r, e) -> timer.stop(e)).thenApply(v -> v.updated()); } @Override public CompletableFuture<Boolean> replace(K key, long oldVersion, V newValue) { final MeteringAgent.Context timer = monitor.startTimer(REPLACE); return updateAndGet(key, Match.any(), Match.ifValue(oldVersion), newValue) .whenComplete((r, e) -> timer.stop(e)).thenApply(v -> v.updated()); } private Map.Entry<K, Versioned<V>> mapRawEntry(Map.Entry<String, Versioned<byte[]>> e) { return Maps.immutableEntry(dK(e.getKey()), e.getValue().<V>map(serializer::decode)); } private CompletableFuture<UpdateResult<K, V>> updateAndGet(K key, Match<V> oldValueMatch, Match<Long> oldVersionMatch, V value) { checkIfUnmodifiable(); return database .mapUpdate(name, keyCache.getUnchecked(key), oldValueMatch.map(serializer::encode), oldVersionMatch, value == null ? null : serializer.encode(value)) .thenApply(this::unwrapResult).thenApply(r -> r.<K, V>map(this::dK, serializer::decode)); } private <T> T unwrapResult(Result<T> result) { if (result.status() == Result.Status.LOCKED) { throw new ConsistentMapException.ConcurrentModification(); } else if (result.success()) { return result.value(); } else { throw new IllegalStateException("Must not be here"); } } private void checkIfUnmodifiable() { if (readOnly) { throw new UnsupportedOperationException(); } } @Override public void addListener(MapEventListener<K, V> listener) { listeners.add(listener); } @Override public void removeListener(MapEventListener<K, V> listener) { listeners.remove(listener); } protected void notifyListeners(MapEvent<K, V> event) { if (event == null) { return; } listeners.forEach(listener -> { try { listener.event(event); } catch (Exception e) { log.warn("Failure notifying listener about {}", event, e); } }); } }