| /** |
| * 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.hadoop.hbase.regionserver.wal; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.hbase.HConstants; |
| import org.apache.hadoop.hbase.HRegionInfo; |
| import org.apache.hadoop.hbase.classification.InterfaceAudience; |
| import org.apache.hadoop.hbase.util.Bytes; |
| import org.apache.hadoop.hbase.util.ImmutableByteArray; |
| |
| /** |
| * Accounting of sequence ids per region and then by column family. So we can our accounting |
| * current, call startCacheFlush and then finishedCacheFlush or abortCacheFlush so this instance can |
| * keep abreast of the state of sequence id persistence. Also call update per append. |
| * <p> |
| * For the implementation, we assume that all the {@code encodedRegionName} passed in is gotten by |
| * {@link HRegionInfo#getEncodedNameAsBytes()}. So it is safe to use it as a hash key. And for |
| * family name, we use {@link ImmutableByteArray} as key. This is because hash based map is much |
| * faster than RBTree or CSLM and here we are on the critical write path. See HBASE-16278 for more |
| * details. |
| */ |
| @InterfaceAudience.Private |
| class SequenceIdAccounting { |
| |
| private static final Log LOG = LogFactory.getLog(SequenceIdAccounting.class); |
| /** |
| * This lock ties all operations on {@link SequenceIdAccounting#flushingSequenceIds} and |
| * {@link #lowestUnflushedSequenceIds} Maps. {@link #lowestUnflushedSequenceIds} has the |
| * lowest outstanding sequence ids EXCEPT when flushing. When we flush, the current |
| * lowest set for the region/column family are moved (atomically because of this lock) to |
| * {@link #flushingSequenceIds}. |
| * |
| * <p>The two Maps are tied by this locking object EXCEPT when we go to update the lowest |
| * entry; see {@link #lowest(byte[], Set, Long)}. In here is a putIfAbsent call on |
| * {@link #lowestUnflushedSequenceIds}. In this latter case, we will add this lowest |
| * sequence id if we find that there is no entry for the current column family. There will be no |
| * entry only if we just came up OR we have moved aside current set of lowest sequence ids |
| * because the current set are being flushed (by putting them into {@link #flushingSequenceIds}). |
| * This is how we pick up the next 'lowest' sequence id per region per column family to be used |
| * figuring what is in the next flush. |
| */ |
| private final Object tieLock = new Object(); |
| |
| /** |
| * Map of encoded region names and family names to their OLDEST -- i.e. their first, |
| * the longest-lived, their 'earliest', the 'lowest' -- sequence id. |
| * |
| * <p>When we flush, the current lowest sequence ids get cleared and added to |
| * {@link #flushingSequenceIds}. The next append that comes in, is then added |
| * here to {@link #lowestUnflushedSequenceIds} as the next lowest sequenceid. |
| * |
| * <p>If flush fails, currently server is aborted so no need to restore previous sequence ids. |
| * <p>Needs to be concurrent Maps because we use putIfAbsent updating oldest. |
| */ |
| private final ConcurrentMap<byte[], ConcurrentMap<ImmutableByteArray, Long>> |
| lowestUnflushedSequenceIds = new ConcurrentHashMap<>(); |
| |
| /** |
| * Map of encoded region names and family names to their lowest or OLDEST sequence/edit id |
| * currently being flushed out to hfiles. Entries are moved here from |
| * {@link #lowestUnflushedSequenceIds} while the lock {@link #tieLock} is held |
| * (so movement between the Maps is atomic). |
| */ |
| private final Map<byte[], Map<ImmutableByteArray, Long>> flushingSequenceIds = new HashMap<>(); |
| |
| /** |
| * Map of region encoded names to the latest/highest region sequence id. Updated on each |
| * call to append. |
| * <p> |
| * This map uses byte[] as the key, and uses reference equality. It works in our use case as we |
| * use {@link HRegionInfo#getEncodedNameAsBytes()} as keys. For a given region, it always returns |
| * the same array. |
| */ |
| private Map<byte[], Long> highestSequenceIds = new HashMap<>(); |
| |
| /** |
| * Returns the lowest unflushed sequence id for the region. |
| * @param encodedRegionName |
| * @return Lowest outstanding unflushed sequenceid for <code>encodedRegionName</code>. Will |
| * return {@link HConstants#NO_SEQNUM} when none. |
| */ |
| long getLowestSequenceId(final byte[] encodedRegionName) { |
| synchronized (this.tieLock) { |
| Map<?, Long> m = this.flushingSequenceIds.get(encodedRegionName); |
| long flushingLowest = m != null ? getLowestSequenceId(m) : Long.MAX_VALUE; |
| m = this.lowestUnflushedSequenceIds.get(encodedRegionName); |
| long unflushedLowest = m != null ? getLowestSequenceId(m) : HConstants.NO_SEQNUM; |
| return Math.min(flushingLowest, unflushedLowest); |
| } |
| } |
| |
| /** |
| * @param encodedRegionName |
| * @param familyName |
| * @return Lowest outstanding unflushed sequenceid for <code>encodedRegionname</code> and |
| * <code>familyName</code>. Returned sequenceid may be for an edit currently being |
| * flushed. |
| */ |
| long getLowestSequenceId(final byte[] encodedRegionName, final byte[] familyName) { |
| ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap(familyName); |
| synchronized (this.tieLock) { |
| Map<ImmutableByteArray, Long> m = this.flushingSequenceIds.get(encodedRegionName); |
| if (m != null) { |
| Long lowest = m.get(familyNameWrapper); |
| if (lowest != null) { |
| return lowest; |
| } |
| } |
| m = this.lowestUnflushedSequenceIds.get(encodedRegionName); |
| if (m != null) { |
| Long lowest = m.get(familyNameWrapper); |
| if (lowest != null) { |
| return lowest; |
| } |
| } |
| } |
| return HConstants.NO_SEQNUM; |
| } |
| |
| /** |
| * Reset the accounting of highest sequenceid by regionname. |
| * @return Return the previous accounting Map of regions to the last sequence id written into |
| * each. |
| */ |
| Map<byte[], Long> resetHighest() { |
| Map<byte[], Long> old = this.highestSequenceIds; |
| this.highestSequenceIds = new HashMap<byte[], Long>(); |
| return old; |
| } |
| |
| /** |
| * We've been passed a new sequenceid for the region. Set it as highest seen for this region and |
| * if we are to record oldest, or lowest sequenceids, save it as oldest seen if nothing |
| * currently older. |
| * @param encodedRegionName |
| * @param families |
| * @param sequenceid |
| * @param lowest Whether to keep running account of oldest sequence id. |
| */ |
| void update(byte[] encodedRegionName, Set<byte[]> families, long sequenceid, |
| final boolean lowest) { |
| Long l = Long.valueOf(sequenceid); |
| this.highestSequenceIds.put(encodedRegionName, l); |
| if (lowest) { |
| ConcurrentMap<ImmutableByteArray, Long> m = getOrCreateLowestSequenceIds(encodedRegionName); |
| for (byte[] familyName : families) { |
| m.putIfAbsent(ImmutableByteArray.wrap(familyName), l); |
| } |
| } |
| } |
| |
| /** |
| * Update the store sequence id, e.g., upon executing in-memory compaction |
| */ |
| void updateStore(byte[] encodedRegionName, byte[] familyName, Long sequenceId, |
| boolean onlyIfGreater) { |
| if (sequenceId == null) { |
| return; |
| } |
| Long highest = this.highestSequenceIds.get(encodedRegionName); |
| if (highest == null || sequenceId > highest) { |
| this.highestSequenceIds.put(encodedRegionName, sequenceId); |
| } |
| ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap(familyName); |
| synchronized (this.tieLock) { |
| ConcurrentMap<ImmutableByteArray, Long> m = getOrCreateLowestSequenceIds(encodedRegionName); |
| boolean replaced = false; |
| while (!replaced) { |
| Long oldSeqId = m.get(familyNameWrapper); |
| if (oldSeqId == null) { |
| m.put(familyNameWrapper, sequenceId); |
| replaced = true; |
| } else if (onlyIfGreater) { |
| if (sequenceId > oldSeqId) { |
| replaced = m.replace(familyNameWrapper, oldSeqId, sequenceId); |
| } else { |
| return; |
| } |
| } else { // replace even if sequence id is not greater than oldSeqId |
| m.put(familyNameWrapper, sequenceId); |
| return; |
| } |
| } |
| } |
| } |
| |
| @VisibleForTesting |
| ConcurrentMap<ImmutableByteArray, Long> getOrCreateLowestSequenceIds(byte[] encodedRegionName) { |
| // Intentionally, this access is done outside of this.regionSequenceIdLock. Done per append. |
| ConcurrentMap<ImmutableByteArray, Long> m = this.lowestUnflushedSequenceIds |
| .get(encodedRegionName); |
| if (m != null) { |
| return m; |
| } |
| m = new ConcurrentHashMap<>(); |
| // Another thread may have added it ahead of us. |
| ConcurrentMap<ImmutableByteArray, Long> alreadyPut = this.lowestUnflushedSequenceIds |
| .putIfAbsent(encodedRegionName, m); |
| return alreadyPut == null ? m : alreadyPut; |
| } |
| |
| /** |
| * @param sequenceids Map to search for lowest value. |
| * @return Lowest value found in <code>sequenceids</code>. |
| */ |
| private static long getLowestSequenceId(Map<?, Long> sequenceids) { |
| long lowest = HConstants.NO_SEQNUM; |
| for (Long sid: sequenceids.values()) { |
| if (lowest == HConstants.NO_SEQNUM || sid.longValue() < lowest) { |
| lowest = sid.longValue(); |
| } |
| } |
| return lowest; |
| } |
| |
| /** |
| * @param src |
| * @return New Map that has same keys as <code>src</code> but instead of a Map for a value, it |
| * instead has found the smallest sequence id and it returns that as the value instead. |
| */ |
| private <T extends Map<?, Long>> Map<byte[], Long> flattenToLowestSequenceId(Map<byte[], T> src) { |
| if (src == null || src.isEmpty()) { |
| return null; |
| } |
| Map<byte[], Long> tgt = new HashMap<>(); |
| for (Map.Entry<byte[], T> entry : src.entrySet()) { |
| long lowestSeqId = getLowestSequenceId(entry.getValue()); |
| if (lowestSeqId != HConstants.NO_SEQNUM) { |
| tgt.put(entry.getKey(), lowestSeqId); |
| } |
| } |
| return tgt; |
| } |
| |
| /** |
| * @param encodedRegionName Region to flush. |
| * @param families Families to flush. May be a subset of all families in the region. |
| * @return Returns {@link HConstants#NO_SEQNUM} if we are flushing the whole region OR if |
| * we are flushing a subset of all families but there are no edits in those families not |
| * being flushed; in other words, this is effectively same as a flush of all of the region |
| * though we were passed a subset of regions. Otherwise, it returns the sequence id of the |
| * oldest/lowest outstanding edit. |
| */ |
| Long startCacheFlush(final byte[] encodedRegionName, final Set<byte[]> families) { |
| Map<ImmutableByteArray, Long> oldSequenceIds = null; |
| Long lowestUnflushedInRegion = HConstants.NO_SEQNUM; |
| synchronized (tieLock) { |
| Map<ImmutableByteArray, Long> m = this.lowestUnflushedSequenceIds.get(encodedRegionName); |
| if (m != null) { |
| // NOTE: Removal from this.lowestUnflushedSequenceIds must be done in controlled |
| // circumstance because another concurrent thread now may add sequenceids for this family |
| // (see above in getOrCreateLowestSequenceId). Make sure you are ok with this. Usually it |
| // is fine because updates are blocked when this method is called. Make sure!!! |
| for (byte[] familyName : families) { |
| ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap(familyName); |
| Long seqId = m.remove(familyNameWrapper); |
| if (seqId != null) { |
| if (oldSequenceIds == null) { |
| oldSequenceIds = new HashMap<>(); |
| } |
| oldSequenceIds.put(familyNameWrapper, seqId); |
| } |
| } |
| if (oldSequenceIds != null && !oldSequenceIds.isEmpty()) { |
| if (this.flushingSequenceIds.put(encodedRegionName, oldSequenceIds) != null) { |
| LOG.warn("Flushing Map not cleaned up for " + Bytes.toString(encodedRegionName) + |
| ", sequenceid=" + oldSequenceIds); |
| } |
| } |
| if (m.isEmpty()) { |
| // Remove it otherwise it will be in oldestUnflushedStoreSequenceIds for ever |
| // even if the region is already moved to other server. |
| // Do not worry about data racing, we held write lock of region when calling |
| // startCacheFlush, so no one can add value to the map we removed. |
| this.lowestUnflushedSequenceIds.remove(encodedRegionName); |
| } else { |
| // Flushing a subset of the region families. Return the sequence id of the oldest entry. |
| lowestUnflushedInRegion = Collections.min(m.values()); |
| } |
| } |
| } |
| // Do this check outside lock. |
| if (oldSequenceIds != null && oldSequenceIds.isEmpty()) { |
| // TODO: if we have no oldStoreSeqNum, and WAL is not disabled, presumably either |
| // the region is already flushing (which would make this call invalid), or there |
| // were no appends after last flush, so why are we starting flush? Maybe we should |
| // assert not empty. Less rigorous, but safer, alternative is telling the caller to stop. |
| // For now preserve old logic. |
| LOG.warn("Couldn't find oldest sequenceid for " + Bytes.toString(encodedRegionName)); |
| } |
| return lowestUnflushedInRegion; |
| } |
| |
| void completeCacheFlush(final byte[] encodedRegionName) { |
| synchronized (tieLock) { |
| this.flushingSequenceIds.remove(encodedRegionName); |
| } |
| } |
| |
| void abortCacheFlush(final byte[] encodedRegionName) { |
| // Method is called when we are crashing down because failed write flush AND it is called |
| // if we fail prepare. The below is for the fail prepare case; we restore the old sequence ids. |
| Map<ImmutableByteArray, Long> flushing = null; |
| Map<ImmutableByteArray, Long> tmpMap = new HashMap<>(); |
| // Here we are moving sequenceids from flushing back to unflushed; doing opposite of what |
| // happened in startCacheFlush. During prepare phase, we have update lock on the region so |
| // no edits should be coming in via append. |
| synchronized (tieLock) { |
| flushing = this.flushingSequenceIds.remove(encodedRegionName); |
| if (flushing != null) { |
| Map<ImmutableByteArray, Long> unflushed = getOrCreateLowestSequenceIds(encodedRegionName); |
| for (Map.Entry<ImmutableByteArray, Long> e: flushing.entrySet()) { |
| // Set into unflushed the 'old' oldest sequenceid and if any value in flushed with this |
| // value, it will now be in tmpMap. |
| tmpMap.put(e.getKey(), unflushed.put(e.getKey(), e.getValue())); |
| } |
| } |
| } |
| |
| // Here we are doing some 'test' to see if edits are going in out of order. What is it for? |
| // Carried over from old code. |
| if (flushing != null) { |
| for (Map.Entry<ImmutableByteArray, Long> e : flushing.entrySet()) { |
| Long currentId = tmpMap.get(e.getKey()); |
| if (currentId != null && currentId.longValue() <= e.getValue().longValue()) { |
| String errorStr = Bytes.toString(encodedRegionName) + " family " |
| + e.getKey().toStringUtf8() + " acquired edits out of order current memstore seq=" |
| + currentId + ", previous oldest unflushed id=" + e.getValue(); |
| LOG.error(errorStr); |
| Runtime.getRuntime().halt(1); |
| } |
| } |
| } |
| } |
| |
| /** |
| * See if passed <code>sequenceids</code> are lower -- i.e. earlier -- than any outstanding |
| * sequenceids, sequenceids we are holding on to in this accounting instance. |
| * @param sequenceids Keyed by encoded region name. Cannot be null (doesn't make sense for it to |
| * be null). |
| * @return true if all sequenceids are lower, older than, the old sequenceids in this instance. |
| */ |
| boolean areAllLower(Map<byte[], Long> sequenceids) { |
| Map<byte[], Long> flushing = null; |
| Map<byte[], Long> unflushed = null; |
| synchronized (this.tieLock) { |
| // Get a flattened -- only the oldest sequenceid -- copy of current flushing and unflushed |
| // data structures to use in tests below. |
| flushing = flattenToLowestSequenceId(this.flushingSequenceIds); |
| unflushed = flattenToLowestSequenceId(this.lowestUnflushedSequenceIds); |
| } |
| for (Map.Entry<byte[], Long> e : sequenceids.entrySet()) { |
| long oldestFlushing = Long.MAX_VALUE; |
| long oldestUnflushed = Long.MAX_VALUE; |
| if (flushing != null && flushing.containsKey(e.getKey())) { |
| oldestFlushing = flushing.get(e.getKey()); |
| } |
| if (unflushed != null && unflushed.containsKey(e.getKey())) { |
| oldestUnflushed = unflushed.get(e.getKey()); |
| } |
| long min = Math.min(oldestFlushing, oldestUnflushed); |
| if (min <= e.getValue()) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * Iterates over the given Map and compares sequence ids with corresponding entries in |
| * {@link #oldestUnflushedRegionSequenceIds}. If a region in |
| * {@link #oldestUnflushedRegionSequenceIds} has a sequence id less than that passed in |
| * <code>sequenceids</code> then return it. |
| * @param sequenceids Sequenceids keyed by encoded region name. |
| * @return regions found in this instance with sequence ids less than those passed in. |
| */ |
| byte[][] findLower(Map<byte[], Long> sequenceids) { |
| List<byte[]> toFlush = null; |
| // Keeping the old behavior of iterating unflushedSeqNums under oldestSeqNumsLock. |
| synchronized (tieLock) { |
| for (Map.Entry<byte[], Long> e : sequenceids.entrySet()) { |
| Map<ImmutableByteArray, Long> m = this.lowestUnflushedSequenceIds.get(e.getKey()); |
| if (m == null) { |
| continue; |
| } |
| // The lowest sequence id outstanding for this region. |
| long lowest = getLowestSequenceId(m); |
| if (lowest != HConstants.NO_SEQNUM && lowest <= e.getValue()) { |
| if (toFlush == null) { |
| toFlush = new ArrayList<byte[]>(); |
| } |
| toFlush.add(e.getKey()); |
| } |
| } |
| } |
| return toFlush == null ? null : toFlush.toArray(new byte[0][]); |
| } |
| } |