Java tutorial
/* * 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.cassandra.db.compaction; import java.util.Arrays; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import java.util.UUID; import java.util.concurrent.TimeUnit; import com.google.common.base.Predicate; import com.google.common.collect.Iterables; import com.google.common.collect.Sets; import org.apache.cassandra.db.compaction.writers.CompactionAwareWriter; import org.apache.cassandra.db.compaction.writers.DefaultCompactionWriter; import org.apache.cassandra.io.sstable.format.SSTableFormat; import org.apache.cassandra.io.sstable.format.SSTableReader; import org.apache.commons.lang3.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.apache.cassandra.config.DatabaseDescriptor; import org.apache.cassandra.db.ColumnFamilyStore; import org.apache.cassandra.db.SystemKeyspace; import org.apache.cassandra.db.compaction.CompactionManager.CompactionExecutorStatsCollector; import org.apache.cassandra.db.lifecycle.LifecycleTransaction; import org.apache.cassandra.service.ActiveRepairService; import org.apache.cassandra.utils.CloseableIterator; import org.apache.cassandra.utils.UUIDGen; import org.apache.cassandra.utils.concurrent.Refs; public class CompactionTask extends AbstractCompactionTask { protected static final Logger logger = LoggerFactory.getLogger(CompactionTask.class); protected final int gcBefore; private final boolean offline; protected static long totalBytesCompacted = 0; private CompactionExecutorStatsCollector collector; public CompactionTask(ColumnFamilyStore cfs, LifecycleTransaction txn, int gcBefore, boolean offline) { super(cfs, txn); this.gcBefore = gcBefore; this.offline = offline; } public static synchronized long addToTotalBytesCompacted(long bytesCompacted) { return totalBytesCompacted += bytesCompacted; } protected int executeInternal(CompactionExecutorStatsCollector collector) { this.collector = collector; run(); return transaction.originals().size(); } public boolean reduceScopeForLimitedSpace() { if (partialCompactionsAcceptable() && transaction.originals().size() > 1) { // Try again w/o the largest one. logger.warn("insufficient space to compact all requested files {}", StringUtils.join(transaction.originals(), ", ")); // Note that we have removed files that are still marked as compacting. // This suboptimal but ok since the caller will unmark all the sstables at the end. SSTableReader removedSSTable = cfs.getMaxSizeFile(transaction.originals()); transaction.cancel(removedSSTable); return true; } return false; } /** * For internal use and testing only. The rest of the system should go through the submit* methods, * which are properly serialized. * Caller is in charge of marking/unmarking the sstables as compacting. */ protected void runMayThrow() throws Exception { // The collection of sstables passed may be empty (but not null); even if // it is not empty, it may compact down to nothing if all rows are deleted. assert transaction != null; if (transaction.originals().isEmpty()) return; // Note that the current compaction strategy, is not necessarily the one this task was created under. // This should be harmless; see comments to CFS.maybeReloadCompactionStrategy. AbstractCompactionStrategy strategy = cfs.getCompactionStrategy(); if (DatabaseDescriptor.isSnapshotBeforeCompaction()) cfs.snapshotWithoutFlush(System.currentTimeMillis() + "-compact-" + cfs.name); // note that we need to do a rough estimate early if we can fit the compaction on disk - this is pessimistic, but // since we might remove sstables from the compaction in checkAvailableDiskSpace it needs to be done here long expectedWriteSize = cfs.getExpectedCompactedFileSize(transaction.originals(), compactionType); long earlySSTableEstimate = Math.max(1, expectedWriteSize / strategy.getMaxSSTableBytes()); checkAvailableDiskSpace(earlySSTableEstimate, expectedWriteSize); // sanity check: all sstables must belong to the same cfs assert !Iterables.any(transaction.originals(), new Predicate<SSTableReader>() { @Override public boolean apply(SSTableReader sstable) { return !sstable.descriptor.cfname.equals(cfs.name); } }); UUID taskId = SystemKeyspace.startCompaction(cfs, transaction.originals()); // new sstables from flush can be added during a compaction, but only the compaction can remove them, // so in our single-threaded compaction world this is a valid way of determining if we're compacting // all the sstables (that existed when we started) StringBuilder ssTableLoggerMsg = new StringBuilder("["); for (SSTableReader sstr : transaction.originals()) { ssTableLoggerMsg.append(String.format("%s:level=%d, ", sstr.getFilename(), sstr.getSSTableLevel())); } ssTableLoggerMsg.append("]"); String taskIdLoggerMsg = taskId == null ? UUIDGen.getTimeUUID().toString() : taskId.toString(); logger.debug("Compacting ({}) {}", taskIdLoggerMsg, ssTableLoggerMsg); long start = System.nanoTime(); long totalKeysWritten = 0; long estimatedKeys = 0; try (CompactionController controller = getCompactionController(transaction.originals())) { Set<SSTableReader> actuallyCompact = Sets.difference(transaction.originals(), controller.getFullyExpiredSSTables()); SSTableFormat.Type sstableFormat = getFormatType(transaction.originals()); List<SSTableReader> newSStables; AbstractCompactionIterable ci; // SSTableScanners need to be closed before markCompactedSSTablesReplaced call as scanners contain references // to both ifile and dfile and SSTR will throw deletion errors on Windows if it tries to delete before scanner is closed. // See CASSANDRA-8019 and CASSANDRA-8399 try (Refs<SSTableReader> refs = Refs.ref(actuallyCompact); AbstractCompactionStrategy.ScannerList scanners = strategy.getScanners(actuallyCompact)) { ci = new CompactionIterable(compactionType, scanners.scanners, controller, sstableFormat, taskId); try (CloseableIterator<AbstractCompactedRow> iter = ci.iterator()) { if (collector != null) collector.beginCompaction(ci); long lastCheckObsoletion = start; if (!controller.cfs.getCompactionStrategy().isActive) throw new CompactionInterruptedException(ci.getCompactionInfo()); try (CompactionAwareWriter writer = getCompactionAwareWriter(cfs, transaction, actuallyCompact)) { estimatedKeys = writer.estimatedKeys(); while (iter.hasNext()) { if (ci.isStopRequested()) throw new CompactionInterruptedException(ci.getCompactionInfo()); try (AbstractCompactedRow row = iter.next()) { if (writer.append(row)) totalKeysWritten++; if (System.nanoTime() - lastCheckObsoletion > TimeUnit.MINUTES.toNanos(1L)) { controller.maybeRefreshOverlaps(); lastCheckObsoletion = System.nanoTime(); } } } // don't replace old sstables yet, as we need to mark the compaction finished in the system table newSStables = writer.finish(); } finally { // point of no return -- the new sstables are live on disk; next we'll start deleting the old ones // (in replaceCompactedSSTables) if (taskId != null) SystemKeyspace.finishCompaction(taskId); if (collector != null) collector.finishCompaction(ci); } } } // log a bunch of statistics about the result and save to system table compaction_history long dTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start); long startsize = SSTableReader.getTotalBytes(transaction.originals()); long endsize = SSTableReader.getTotalBytes(newSStables); double ratio = (double) endsize / (double) startsize; StringBuilder newSSTableNames = new StringBuilder(); for (SSTableReader reader : newSStables) newSSTableNames.append(reader.descriptor.baseFilename()).append(","); double mbps = dTime > 0 ? (double) endsize / (1024 * 1024) / ((double) dTime / 1000) : 0; long totalSourceRows = 0; String mergeSummary = updateCompactionHistory(cfs.keyspace.getName(), cfs.getColumnFamilyName(), ci, startsize, endsize); logger.debug(String.format( "Compacted (%s) %d sstables to [%s] to level=%d. %,d bytes to %,d (~%d%% of original) in %,dms = %fMB/s. %,d total partitions merged to %,d. Partition merge counts were {%s}", taskIdLoggerMsg, transaction.originals().size(), newSSTableNames.toString(), getLevel(), startsize, endsize, (int) (ratio * 100), dTime, mbps, totalSourceRows, totalKeysWritten, mergeSummary)); logger.trace(String.format("CF Total Bytes Compacted: %,d", CompactionTask.addToTotalBytesCompacted(endsize))); logger.trace("Actual #keys: {}, Estimated #keys:{}, Err%: {}", totalKeysWritten, estimatedKeys, ((double) (totalKeysWritten - estimatedKeys) / totalKeysWritten)); if (offline) Refs.release(Refs.selfRefs(newSStables)); } } @Override public CompactionAwareWriter getCompactionAwareWriter(ColumnFamilyStore cfs, LifecycleTransaction transaction, Set<SSTableReader> nonExpiredSSTables) { return new DefaultCompactionWriter(cfs, transaction, nonExpiredSSTables, offline, compactionType); } public static String updateCompactionHistory(String keyspaceName, String columnFamilyName, AbstractCompactionIterable ci, long startSize, long endSize) { long[] counts = ci.getMergedRowCounts(); StringBuilder mergeSummary = new StringBuilder(counts.length * 10); Map<Integer, Long> mergedRows = new HashMap<>(); for (int i = 0; i < counts.length; i++) { long count = counts[i]; if (count == 0) continue; int rows = i + 1; mergeSummary.append(String.format("%d:%d, ", rows, count)); mergedRows.put(rows, count); } SystemKeyspace.updateCompactionHistory(keyspaceName, columnFamilyName, System.currentTimeMillis(), startSize, endSize, mergedRows); return mergeSummary.toString(); } public static long getMinRepairedAt(Set<SSTableReader> actuallyCompact) { long minRepairedAt = Long.MAX_VALUE; for (SSTableReader sstable : actuallyCompact) minRepairedAt = Math.min(minRepairedAt, sstable.getSSTableMetadata().repairedAt); if (minRepairedAt == Long.MAX_VALUE) return ActiveRepairService.UNREPAIRED_SSTABLE; return minRepairedAt; } protected void checkAvailableDiskSpace(long estimatedSSTables, long expectedWriteSize) { while (!cfs.directories.hasAvailableDiskSpace(estimatedSSTables, expectedWriteSize)) { if (!reduceScopeForLimitedSpace()) throw new RuntimeException(String.format( "Not enough space for compaction, estimated sstables = %d, expected write size = %d", estimatedSSTables, expectedWriteSize)); } } protected int getLevel() { return 0; } protected CompactionController getCompactionController(Set<SSTableReader> toCompact) { return new CompactionController(cfs, toCompact, gcBefore); } protected boolean partialCompactionsAcceptable() { return !isUserDefined; } public static long getMaxDataAge(Collection<SSTableReader> sstables) { long max = 0; for (SSTableReader sstable : sstables) { if (sstable.maxDataAge > max) max = sstable.maxDataAge; } return max; } public static SSTableFormat.Type getFormatType(Collection<SSTableReader> sstables) { if (sstables.isEmpty() || !SSTableFormat.enableSSTableDevelopmentTestMode) return DatabaseDescriptor.getSSTableFormat(); //Allows us to test compaction of non-default formats return sstables.iterator().next().descriptor.formatType; } }