sijie closed pull request #843: DbLedgerStorage -- ReadCache URL: https://github.com/apache/bookkeeper/pull/843
This is a PR merged from a forked repository. As GitHub hides the original diff on merge, it is displayed below for the sake of provenance: As this is a foreign pull request (from a fork), the diff is supplied below (as it won't show otherwise due to GitHub magic): diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCache.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCache.java new file mode 100644 index 000000000..b14478fcc --- /dev/null +++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCache.java @@ -0,0 +1,197 @@ +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.bookkeeper.bookie.storage.ldb; + +import static org.apache.bookkeeper.bookie.storage.ldb.WriteCache.align64; + +import io.netty.buffer.ByteBuf; +import io.netty.buffer.ByteBufAllocator; +import io.netty.buffer.Unpooled; + +import java.io.Closeable; +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.concurrent.locks.ReentrantReadWriteLock; + +import org.apache.bookkeeper.util.collections.ConcurrentLongLongPairHashMap; +import org.apache.bookkeeper.util.collections.ConcurrentLongLongPairHashMap.LongPair; + +/** + * Read cache implementation. + * + * <p>Uses the specified amount of memory and pairs it with a hashmap. + * + * <p>The memory is splitted in multiple segments that are used in a + * ring-buffer fashion. When the read cache is full, the oldest segment + * is cleared and rotated to make space for new entries to be added to + * the read cache. + */ +public class ReadCache implements Closeable { + + private static final int DEFAULT_MAX_SEGMENT_SIZE = 1 * 1024 * 1024 * 1024; + + private final List<ByteBuf> cacheSegments; + private final List<ConcurrentLongLongPairHashMap> cacheIndexes; + + private int currentSegmentIdx; + private final AtomicInteger currentSegmentOffset = new AtomicInteger(0); + + private final int segmentSize; + + private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock(); + + public ReadCache(long maxCacheSize) { + this(maxCacheSize, DEFAULT_MAX_SEGMENT_SIZE); + } + + public ReadCache(long maxCacheSize, int maxSegmentSize) { + int segmentsCount = Math.max(2, (int) (maxCacheSize / maxSegmentSize)); + segmentSize = (int) (maxCacheSize / segmentsCount); + + cacheSegments = new ArrayList<>(); + cacheIndexes = new ArrayList<>(); + + for (int i = 0; i < segmentsCount; i++) { + cacheSegments.add(Unpooled.directBuffer(segmentSize, segmentSize)); + cacheIndexes.add(new ConcurrentLongLongPairHashMap(4096, 2 * Runtime.getRuntime().availableProcessors())); + } + } + + @Override + public void close() { + cacheSegments.forEach(ByteBuf::release); + } + + public void put(long ledgerId, long entryId, ByteBuf entry) { + int entrySize = entry.readableBytes(); + int alignedSize = align64(entrySize); + + lock.readLock().lock(); + + try { + int offset = currentSegmentOffset.getAndAdd(alignedSize); + if (offset + entrySize > segmentSize) { + // Roll-over the segment (outside the read-lock) + } else { + // Copy entry into read cache segment + cacheSegments.get(currentSegmentIdx).setBytes(offset, entry, entry.readerIndex(), + entry.readableBytes()); + cacheIndexes.get(currentSegmentIdx).put(ledgerId, entryId, offset, entrySize); + return; + } + } finally { + lock.readLock().unlock(); + } + + // We could not insert in segment, we to get the write lock and roll-over to + // next segment + lock.writeLock().lock(); + + try { + int offset = currentSegmentOffset.getAndAdd(entrySize); + if (offset + entrySize > segmentSize) { + // Rollover to next segment + currentSegmentIdx = (currentSegmentIdx + 1) % cacheSegments.size(); + currentSegmentOffset.set(alignedSize); + cacheIndexes.get(currentSegmentIdx).clear(); + offset = 0; + } + + // Copy entry into read cache segment + cacheSegments.get(currentSegmentIdx).setBytes(offset, entry, entry.readerIndex(), entry.readableBytes()); + cacheIndexes.get(currentSegmentIdx).put(ledgerId, entryId, offset, entrySize); + } finally { + lock.writeLock().unlock(); + } + } + + public ByteBuf get(long ledgerId, long entryId) { + lock.readLock().lock(); + + try { + // We need to check all the segments, starting from the current one and looking + // backward to minimize the + // checks for recently inserted entries + int size = cacheSegments.size(); + for (int i = 0; i < size; i++) { + int segmentIdx = (currentSegmentIdx + (size - i)) % size; + + LongPair res = cacheIndexes.get(segmentIdx).get(ledgerId, entryId); + if (res != null) { + int entryOffset = (int) res.first; + int entryLen = (int) res.second; + + ByteBuf entry = ByteBufAllocator.DEFAULT.directBuffer(entryLen, entryLen); + entry.writeBytes(cacheSegments.get(segmentIdx), entryOffset, entryLen); + return entry; + } + } + } finally { + lock.readLock().unlock(); + } + + // Entry not found in any segment + return null; + } + + /** + * @return the total size of cached entries + */ + public long size() { + lock.readLock().lock(); + + try { + long size = 0; + for (int i = 0; i < cacheIndexes.size(); i++) { + if (i == currentSegmentIdx) { + size += currentSegmentOffset.get(); + } else if (!cacheIndexes.get(i).isEmpty()) { + size += segmentSize; + } else { + // the segment is empty + } + } + + return size; + } finally { + lock.readLock().unlock(); + } + } + + /** + * @return the total number of cached entries + */ + public long count() { + lock.readLock().lock(); + + try { + long count = 0; + for (int i = 0; i < cacheIndexes.size(); i++) { + count += cacheIndexes.get(i).size(); + } + + return count; + } finally { + lock.readLock().unlock(); + } + } +} diff --git a/bookkeeper-server/src/test/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCacheTest.java b/bookkeeper-server/src/test/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCacheTest.java new file mode 100644 index 000000000..42e509963 --- /dev/null +++ b/bookkeeper-server/src/test/java/org/apache/bookkeeper/bookie/storage/ldb/ReadCacheTest.java @@ -0,0 +1,118 @@ +/** + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.bookkeeper.bookie.storage.ldb; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertNull; + +import io.netty.buffer.ByteBuf; +import io.netty.buffer.Unpooled; + +import org.junit.Test; + +/** + * Unit test for {@link ReadCache}. + */ +public class ReadCacheTest { + + @Test + public void simple() { + ReadCache cache = new ReadCache(10 * 1024); + + assertEquals(0, cache.count()); + assertEquals(0, cache.size()); + + ByteBuf entry = Unpooled.wrappedBuffer(new byte[1024]); + cache.put(1, 0, entry); + + assertEquals(1, cache.count()); + assertEquals(1024, cache.size()); + + assertEquals(entry, cache.get(1, 0)); + assertNull(cache.get(1, 1)); + + for (int i = 1; i < 10; i++) { + cache.put(1, i, entry); + } + + assertEquals(10, cache.count()); + assertEquals(10 * 1024, cache.size()); + + cache.put(1, 10, entry); + + // First half of entries will have been evicted + for (int i = 0; i < 5; i++) { + assertNull(cache.get(1, i)); + } + + for (int i = 5; i < 11; i++) { + assertEquals(entry, cache.get(1, i)); + } + + cache.close(); + } + + @Test + public void emptyCache() { + ReadCache cache = new ReadCache(10 * 1024); + + assertEquals(0, cache.count()); + assertEquals(0, cache.size()); + assertEquals(null, cache.get(0, 0)); + + cache.close(); + } + + @Test + public void multipleSegments() { + // Test with multiple smaller segments + ReadCache cache = new ReadCache(10 * 1024, 2 * 1024); + + assertEquals(0, cache.count()); + assertEquals(0, cache.size()); + + for (int i = 0; i < 10; i++) { + ByteBuf entry = Unpooled.wrappedBuffer(new byte[1024]); + entry.setInt(0, i); + cache.put(1, i, entry); + } + + for (int i = 0; i < 10; i++) { + ByteBuf res = cache.get(1, i); + assertEquals(1, res.refCnt()); + + assertEquals(1024, res.readableBytes()); + assertEquals(i, res.getInt(0)); + } + + assertEquals(10, cache.count()); + assertEquals(10 * 1024, cache.size()); + + // Putting one more entry, should trigger the 1st segment rollover + ByteBuf entry = Unpooled.wrappedBuffer(new byte[1024]); + cache.put(2, 0, entry); + + assertEquals(9, cache.count()); + assertEquals(9 * 1024, cache.size()); + + cache.close(); + } +} ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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