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Before, the chunk cache(s) was a wrapper over `DefaultChunkManager`. In some situations, this is not very convenient and also the cache has more responsibilities than it should (like prefetching). This commit refactors the cache to be a pluggable mechanism in the chunk manager.
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131 changes: 131 additions & 0 deletions
131
core/src/main/java/io/aiven/kafka/tieredstorage/chunkmanager/cache/AbstractChunkCache.java
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| /* | ||
| * Copyright 2023 Aiven Oy | ||
| * | ||
| * 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. | ||
| */ | ||
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| package io.aiven.kafka.tieredstorage.chunkmanager.cache; | ||
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| import java.io.IOException; | ||
| import java.io.InputStream; | ||
| import java.util.concurrent.CompletableFuture; | ||
| import java.util.concurrent.CompletionException; | ||
| import java.util.concurrent.ExecutionException; | ||
| import java.util.concurrent.Executor; | ||
| import java.util.concurrent.ForkJoinPool; | ||
| import java.util.concurrent.TimeUnit; | ||
| import java.util.concurrent.TimeoutException; | ||
| import java.util.concurrent.atomic.AtomicReference; | ||
| import java.util.function.Supplier; | ||
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| import io.aiven.kafka.tieredstorage.chunkmanager.ChunkKey; | ||
| import io.aiven.kafka.tieredstorage.metrics.CaffeineStatsCounter; | ||
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| import com.github.benmanes.caffeine.cache.AsyncCache; | ||
| import com.github.benmanes.caffeine.cache.Caffeine; | ||
| import com.github.benmanes.caffeine.cache.RemovalListener; | ||
| import com.github.benmanes.caffeine.cache.Scheduler; | ||
| import com.github.benmanes.caffeine.cache.Weigher; | ||
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| public abstract class AbstractChunkCache<T> extends BaseChunkCache<T> { | ||
| private static final long GET_TIMEOUT_SEC = 10; | ||
| private static final String METRIC_GROUP = "chunk-cache"; | ||
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| private final Executor executor = new ForkJoinPool(); | ||
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| private final CaffeineStatsCounter statsCounter = new CaffeineStatsCounter(METRIC_GROUP); | ||
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| protected AsyncCache<ChunkKey, T> cache; | ||
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| /** | ||
| * Get a chunk from the cache. | ||
| * | ||
| * <p>If the chunk is not present in the cache, use {@literal chunkSupplier} to get it and cache. | ||
| * | ||
| * <p>Since it's not possible to cache an opened InputStream, the actual data is cached, and everytime | ||
| * there is a call to cache the InputStream is recreated from the data stored in cache and stored into local | ||
| * variable. This also allows solving the race condition between eviction and fetching. Since the InputStream is | ||
| * opened right when fetching from cache happens even if the actual value is removed from the cache, | ||
| * the InputStream will still contain the data. | ||
| */ | ||
| @Override | ||
| protected InputStream getChunk0(final ChunkKey chunkKey, | ||
| final Supplier<CompletableFuture<InputStream>> chunkSupplier) | ||
| throws ExecutionException, InterruptedException, TimeoutException { | ||
| final AtomicReference<InputStream> result = new AtomicReference<>(); | ||
| return cache.asMap() | ||
| .compute(chunkKey, (key, val) -> { | ||
| if (val == null) { | ||
| statsCounter.recordMiss(); | ||
| // TODO do not put a failed future into the cache | ||
| return chunkSupplier.get().thenApplyAsync(chunk -> { | ||
| try { | ||
| final T t = this.cacheChunk(chunkKey, chunk); | ||
| result.getAndSet(cachedChunkToInputStream(t)); | ||
| return t; | ||
| } catch (final IOException e) { | ||
| throw new CompletionException(e); | ||
| } | ||
| }, executor); | ||
| } else { | ||
| statsCounter.recordHit(); | ||
| return CompletableFuture.supplyAsync(() -> { | ||
| try { | ||
| final T cachedChunk = val.get(); | ||
| result.getAndSet(cachedChunkToInputStream(cachedChunk)); | ||
| return cachedChunk; | ||
| } catch (final InterruptedException | ExecutionException e) { | ||
| throw new CompletionException(e); | ||
| } | ||
| }, executor); | ||
| } | ||
| }) | ||
| .thenApplyAsync(t -> result.get()) | ||
| .get(GET_TIMEOUT_SEC, TimeUnit.SECONDS); | ||
| } | ||
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| public void supplyIfAbsent(final ChunkKey chunkKey, | ||
| final Supplier<CompletableFuture<InputStream>> chunkSupplier) { | ||
| // TODO do some logging if error | ||
| // TODO do not put a failed future into the cache | ||
| cache.asMap().computeIfAbsent(chunkKey, | ||
| key -> chunkSupplier.get().thenApplyAsync(chunk -> { | ||
| try { | ||
| return this.cacheChunk(chunkKey, chunk); | ||
| } catch (final IOException e) { | ||
| throw new CompletionException(e); | ||
| } | ||
| }, executor)); | ||
| } | ||
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| public abstract InputStream cachedChunkToInputStream(final T cachedChunk); | ||
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| public abstract T cacheChunk(final ChunkKey chunkKey, final InputStream chunk) throws IOException; | ||
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| public abstract RemovalListener<ChunkKey, T> removalListener(); | ||
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| public abstract Weigher<ChunkKey, T> weigher(); | ||
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| protected AsyncCache<ChunkKey, T> buildCache(final ChunkCacheConfig config) { | ||
| final Caffeine<Object, Object> cacheBuilder = Caffeine.newBuilder(); | ||
| config.cacheSize().ifPresent(maximumWeight -> cacheBuilder.maximumWeight(maximumWeight).weigher(weigher())); | ||
| config.cacheRetention().ifPresent(cacheBuilder::expireAfterAccess); | ||
| final var cache = cacheBuilder.evictionListener(removalListener()) | ||
| .scheduler(Scheduler.systemScheduler()) | ||
| .executor(executor) | ||
| .recordStats(() -> statsCounter) | ||
| .buildAsync(); | ||
| statsCounter.registerSizeMetric(cache.synchronous()::estimatedSize); | ||
| return cache; | ||
| } | ||
| } |
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