| // Copyright (C) 2021 The Android Open Source Project |
| // |
| // 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 com.googlesource.gerrit.modules.cache.chroniclemap; |
| |
| import static com.googlesource.gerrit.modules.cache.chroniclemap.ChronicleMapCacheImpl.tryPut; |
| |
| import com.google.common.cache.CacheLoader; |
| import com.google.common.cache.CacheStats; |
| import com.google.common.flogger.FluentLogger; |
| import com.google.common.util.concurrent.FutureCallback; |
| import com.google.common.util.concurrent.Futures; |
| import com.google.common.util.concurrent.ListenableFuture; |
| import com.google.gerrit.server.logging.Metadata; |
| import com.google.gerrit.server.logging.TraceContext; |
| import com.google.gerrit.server.logging.TraceContext.TraceTimer; |
| import com.google.gerrit.server.util.time.TimeUtil; |
| import java.time.Duration; |
| import java.time.Instant; |
| import java.util.Optional; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.atomic.LongAdder; |
| |
| class ChronicleMapCacheLoader<K, V> extends CacheLoader<K, TimedValue<V>> { |
| private static final FluentLogger logger = FluentLogger.forEnclosingClass(); |
| |
| private final Executor storePersistenceExecutor; |
| private final Optional<CacheLoader<K, V>> loader; |
| private final ChronicleMapStore<K, V> store; |
| private final LongAdder loadSuccessCount = new LongAdder(); |
| private final LongAdder loadExceptionCount = new LongAdder(); |
| private final LongAdder totalLoadTime = new LongAdder(); |
| private final LongAdder hitCount = new LongAdder(); |
| private final LongAdder missCount = new LongAdder(); |
| private final Duration expireAfterWrite; |
| |
| /** |
| * Creates a loader for fetching entries from a ChronicleMap store and an external data source. |
| * |
| * @param storePersistenceExecutor executor for async loading/storage to ChronicleMap |
| * @param store the ChronicleMap storage |
| * @param loader the data loader from the external source |
| * @param expireAfterWrite maximum lifetime of the data loaded into ChronicleMap |
| */ |
| ChronicleMapCacheLoader( |
| Executor storePersistenceExecutor, |
| ChronicleMapStore<K, V> store, |
| CacheLoader<K, V> loader, |
| Duration expireAfterWrite) { |
| this.storePersistenceExecutor = storePersistenceExecutor; |
| this.store = store; |
| this.loader = Optional.of(loader); |
| this.expireAfterWrite = expireAfterWrite; |
| } |
| |
| /** |
| * Creates a loader for fetching entries from a ChronicleMap store. |
| * |
| * @param storePersistenceExecutor executor for async loading/storage to ChronicleMap |
| * @param store the ChronicleMap storage |
| * @param expireAfterWrite maximum lifetime of the data loaded into ChronicleMap |
| */ |
| ChronicleMapCacheLoader( |
| Executor storePersistenceExecutor, ChronicleMapStore<K, V> store, Duration expireAfterWrite) { |
| this.storePersistenceExecutor = storePersistenceExecutor; |
| this.store = store; |
| this.loader = Optional.empty(); |
| this.expireAfterWrite = expireAfterWrite; |
| } |
| |
| @Override |
| public TimedValue<V> load(K key) throws Exception { |
| try (TraceTimer timer = |
| TraceContext.newTimer( |
| "Loading value from cache", Metadata.builder().cacheKey(key.toString()).build())) { |
| TimedValue<V> h = loadIfPresent(key); |
| if (h != null) { |
| return h; |
| } |
| |
| if (loader.isPresent()) { |
| missCount.increment(); |
| long start = System.nanoTime(); |
| TimedValue<V> loadedValue = new TimedValue<>(loader.get().load(key)); |
| totalLoadTime.add(System.nanoTime() - start); |
| storePersistenceExecutor.execute( |
| () -> { |
| // Note that we return a loadedValue, even when we |
| // we fail populating the cache with it, to make clients more |
| // resilient to storage cache failures |
| if (tryPut(store, new KeyWrapper<>(key), loadedValue)) { |
| loadSuccessCount.increment(); |
| } |
| }); |
| return loadedValue; |
| } |
| |
| throw new UnsupportedOperationException("No loader defined"); |
| } catch (Exception e) { |
| logger.atWarning().withCause(e).log("Unable to load a value for key='%s'", key); |
| loadExceptionCount.increment(); |
| throw e; |
| } |
| } |
| |
| public ChronicleMapStore<K, V> getStore() { |
| return store; |
| } |
| |
| TimedValue<V> loadIfPresent(K key) { |
| TimedValue<V> h = store.get(new KeyWrapper<>(key)); |
| if (h != null && !expired(h.getCreated())) { |
| hitCount.increment(); |
| return h; |
| } |
| |
| return null; |
| } |
| |
| @Override |
| public ListenableFuture<TimedValue<V>> reload(K key, TimedValue<V> oldValue) throws Exception { |
| if (!loader.isPresent()) { |
| throw new IllegalStateException("No loader defined"); |
| } |
| |
| final long start = System.nanoTime(); |
| ListenableFuture<V> reloadedValue = loader.get().reload(key, oldValue.getValue()); |
| Futures.addCallback( |
| reloadedValue, |
| new FutureCallback<V>() { |
| @Override |
| public void onSuccess(V result) { |
| if (tryPut(store, new KeyWrapper<>(key), new TimedValue<>(result))) { |
| loadSuccessCount.increment(); |
| } |
| totalLoadTime.add(System.nanoTime() - start); |
| } |
| |
| @Override |
| public void onFailure(Throwable t) { |
| logger.atWarning().withCause(t).log("Unable to reload cache value for key='%s'", key); |
| loadExceptionCount.increment(); |
| } |
| }, |
| storePersistenceExecutor); |
| |
| return Futures.transform(reloadedValue, TimedValue::new, storePersistenceExecutor); |
| } |
| |
| boolean expired(long created) { |
| Duration age = Duration.between(Instant.ofEpochMilli(created), TimeUtil.now()); |
| return !expireAfterWrite.isZero() && age.compareTo(expireAfterWrite) > 0; |
| } |
| |
| InMemoryCache<K, V> asInMemoryCacheBypass() { |
| return new InMemoryCache<K, V>() { |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| public TimedValue<V> getIfPresent(Object key) { |
| try { |
| return load((K) key); |
| } catch (Exception e) { |
| return null; |
| } |
| } |
| |
| @Override |
| public TimedValue<V> get(K key, Callable<? extends TimedValue<V>> valueLoader) |
| throws Exception { |
| return valueLoader.call(); |
| } |
| |
| @Override |
| public void put(K key, TimedValue<V> value) { |
| tryPut(store, new KeyWrapper<>(key), value); |
| } |
| |
| @Override |
| public boolean isLoadingCache() { |
| return true; |
| } |
| |
| @Override |
| public TimedValue<V> get(K key) throws ExecutionException { |
| try { |
| return load(key); |
| } catch (Exception e) { |
| throw new ExecutionException(e); |
| } |
| } |
| |
| @Override |
| public void refresh(K key) {} |
| |
| @Override |
| public CacheStats stats() { |
| throw new IllegalArgumentException("Cache stats not available for a loader-bypass"); |
| } |
| |
| @Override |
| public long size() { |
| return 0; |
| } |
| |
| @Override |
| public void invalidate(Object key) {} |
| |
| @Override |
| public void invalidateAll() {} |
| }; |
| } |
| } |