001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.regionserver.wal; 019 020import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent; 021 022import java.util.ArrayList; 023import java.util.Collections; 024import java.util.HashMap; 025import java.util.List; 026import java.util.Map; 027import java.util.Set; 028import java.util.TreeMap; 029import java.util.concurrent.ConcurrentHashMap; 030import java.util.concurrent.ConcurrentMap; 031import java.util.stream.Collectors; 032import org.apache.hadoop.hbase.HConstants; 033import org.apache.hadoop.hbase.util.Bytes; 034import org.apache.hadoop.hbase.util.ImmutableByteArray; 035import org.apache.yetus.audience.InterfaceAudience; 036import org.slf4j.Logger; 037import org.slf4j.LoggerFactory; 038 039/** 040 * Accounting of sequence ids per region and then by column family. So we can keep our accounting 041 * current, call startCacheFlush and then finishedCacheFlush or abortCacheFlush so this instance can 042 * keep abreast of the state of sequence id persistence. Also call update per append. 043 * <p> 044 * For the implementation, we assume that all the {@code encodedRegionName} passed in are gotten by 045 * {@link org.apache.hadoop.hbase.client.RegionInfo#getEncodedNameAsBytes()}. So it is safe to use 046 * it as a hash key. And for family name, we use {@link ImmutableByteArray} as key. This is because 047 * hash based map is much faster than RBTree or CSLM and here we are on the critical write path. See 048 * HBASE-16278 for more details. 049 * </p> 050 */ 051@InterfaceAudience.Private 052class SequenceIdAccounting { 053 private static final Logger LOG = LoggerFactory.getLogger(SequenceIdAccounting.class); 054 055 /** 056 * This lock ties all operations on {@link SequenceIdAccounting#flushingSequenceIds} and 057 * {@link #lowestUnflushedSequenceIds} Maps. {@link #lowestUnflushedSequenceIds} has the lowest 058 * outstanding sequence ids EXCEPT when flushing. When we flush, the current lowest set for the 059 * region/column family are moved (atomically because of this lock) to 060 * {@link #flushingSequenceIds}. 061 * <p> 062 * The two Maps are tied by this locking object EXCEPT when we go to update the lowest entry; see 063 * {@link #lowestUnflushedSequenceIds}. In here is a putIfAbsent call on 064 * {@link #lowestUnflushedSequenceIds}. In this latter case, we will add this lowest sequence id 065 * if we find that there is no entry for the current column family. There will be no entry only if 066 * we just came up OR we have moved aside current set of lowest sequence ids because the current 067 * set are being flushed (by putting them into {@link #flushingSequenceIds}). This is how we pick 068 * up the next 'lowest' sequence id per region per column family to be used figuring what is in 069 * the next flush. 070 */ 071 private final Object tieLock = new Object(); 072 073 /** 074 * Map of encoded region names and family names to their OLDEST -- i.e. their first, the 075 * longest-lived, their 'earliest', the 'lowest' -- sequence id. 076 * <p> 077 * When we flush, the current lowest sequence ids get cleared and added to 078 * {@link #flushingSequenceIds}. The next append that comes in, is then added here to 079 * {@link #lowestUnflushedSequenceIds} as the next lowest sequenceid. 080 * <p> 081 * If flush fails, currently server is aborted so no need to restore previous sequence ids. 082 * <p> 083 * Needs to be concurrent Maps because we use putIfAbsent updating oldest. 084 */ 085 private final ConcurrentMap<byte[], 086 ConcurrentMap<ImmutableByteArray, Long>> lowestUnflushedSequenceIds = new ConcurrentHashMap<>(); 087 088 /** 089 * Map of encoded region names and family names to their lowest or OLDEST sequence/edit id 090 * currently being flushed out to hfiles. Entries are moved here from 091 * {@link #lowestUnflushedSequenceIds} while the lock {@link #tieLock} is held (so movement 092 * between the Maps is atomic). 093 */ 094 private final Map<byte[], Map<ImmutableByteArray, Long>> flushingSequenceIds = new HashMap<>(); 095 096 /** 097 * <p> 098 * Map of region encoded names to the latest/highest region sequence id. Updated on each call to 099 * append. 100 * </p> 101 * <p> 102 * This map uses byte[] as the key, and uses reference equality. It works in our use case as we 103 * use {@link org.apache.hadoop.hbase.client.RegionInfo#getEncodedNameAsBytes()} as keys. For a 104 * given region, it always returns the same array. 105 * </p> 106 */ 107 private Map<byte[], Long> highestSequenceIds = new HashMap<>(); 108 109 /** 110 * Returns the lowest unflushed sequence id for the region. 111 * @return Lowest outstanding unflushed sequenceid for <code>encodedRegionName</code>. Will return 112 * {@link HConstants#NO_SEQNUM} when none. 113 */ 114 long getLowestSequenceId(final byte[] encodedRegionName) { 115 synchronized (this.tieLock) { 116 Map<?, Long> m = this.flushingSequenceIds.get(encodedRegionName); 117 long flushingLowest = m != null ? getLowestSequenceId(m) : Long.MAX_VALUE; 118 m = this.lowestUnflushedSequenceIds.get(encodedRegionName); 119 long unflushedLowest = m != null ? getLowestSequenceId(m) : HConstants.NO_SEQNUM; 120 return Math.min(flushingLowest, unflushedLowest); 121 } 122 } 123 124 /** 125 * @return Lowest outstanding unflushed sequenceid for <code>encodedRegionname</code> and 126 * <code>familyName</code>. Returned sequenceid may be for an edit currently being 127 * flushed. 128 */ 129 long getLowestSequenceId(final byte[] encodedRegionName, final byte[] familyName) { 130 ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap(familyName); 131 synchronized (this.tieLock) { 132 Map<ImmutableByteArray, Long> m = this.flushingSequenceIds.get(encodedRegionName); 133 if (m != null) { 134 Long lowest = m.get(familyNameWrapper); 135 if (lowest != null) { 136 return lowest; 137 } 138 } 139 m = this.lowestUnflushedSequenceIds.get(encodedRegionName); 140 if (m != null) { 141 Long lowest = m.get(familyNameWrapper); 142 if (lowest != null) { 143 return lowest; 144 } 145 } 146 } 147 return HConstants.NO_SEQNUM; 148 } 149 150 /** 151 * Reset the accounting of highest sequenceid by regionname. 152 * @return Return the previous accounting Map of regions to the last sequence id written into 153 * each. 154 */ 155 Map<byte[], Long> resetHighest() { 156 Map<byte[], Long> old = this.highestSequenceIds; 157 this.highestSequenceIds = new HashMap<>(); 158 return old; 159 } 160 161 /** 162 * We've been passed a new sequenceid for the region. Set it as highest seen for this region and 163 * if we are to record oldest, or lowest sequenceids, save it as oldest seen if nothing currently 164 * older. nnn * @param lowest Whether to keep running account of oldest sequence id. 165 */ 166 void update(byte[] encodedRegionName, Set<byte[]> families, long sequenceid, 167 final boolean lowest) { 168 Long l = Long.valueOf(sequenceid); 169 this.highestSequenceIds.put(encodedRegionName, l); 170 if (lowest) { 171 ConcurrentMap<ImmutableByteArray, Long> m = getOrCreateLowestSequenceIds(encodedRegionName); 172 for (byte[] familyName : families) { 173 m.putIfAbsent(ImmutableByteArray.wrap(familyName), l); 174 } 175 } 176 } 177 178 /** 179 * Clear all the records of the given region as it is going to be closed. 180 * <p/> 181 * We will call this once we get the region close marker. We need this because that, if we use 182 * Durability.ASYNC_WAL, after calling startCacheFlush, we may still get some ongoing wal entries 183 * that has not been processed yet, this will lead to orphan records in the 184 * lowestUnflushedSequenceIds and then cause too many WAL files. 185 * <p/> 186 * See HBASE-23157 for more details. 187 */ 188 void onRegionClose(byte[] encodedRegionName) { 189 synchronized (tieLock) { 190 this.lowestUnflushedSequenceIds.remove(encodedRegionName); 191 Map<ImmutableByteArray, Long> flushing = this.flushingSequenceIds.remove(encodedRegionName); 192 if (flushing != null) { 193 LOG.warn("Still have flushing records when closing {}, {}", 194 Bytes.toString(encodedRegionName), 195 flushing.entrySet().stream().map(e -> e.getKey().toString() + "->" + e.getValue()) 196 .collect(Collectors.joining(",", "{", "}"))); 197 } 198 } 199 this.highestSequenceIds.remove(encodedRegionName); 200 } 201 202 /** 203 * Update the store sequence id, e.g., upon executing in-memory compaction 204 */ 205 void updateStore(byte[] encodedRegionName, byte[] familyName, Long sequenceId, 206 boolean onlyIfGreater) { 207 if (sequenceId == null) { 208 return; 209 } 210 Long highest = this.highestSequenceIds.get(encodedRegionName); 211 if (highest == null || sequenceId > highest) { 212 this.highestSequenceIds.put(encodedRegionName, sequenceId); 213 } 214 ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap(familyName); 215 synchronized (this.tieLock) { 216 ConcurrentMap<ImmutableByteArray, Long> m = getOrCreateLowestSequenceIds(encodedRegionName); 217 boolean replaced = false; 218 while (!replaced) { 219 Long oldSeqId = m.get(familyNameWrapper); 220 if (oldSeqId == null) { 221 m.put(familyNameWrapper, sequenceId); 222 replaced = true; 223 } else if (onlyIfGreater) { 224 if (sequenceId > oldSeqId) { 225 replaced = m.replace(familyNameWrapper, oldSeqId, sequenceId); 226 } else { 227 return; 228 } 229 } else { // replace even if sequence id is not greater than oldSeqId 230 m.put(familyNameWrapper, sequenceId); 231 return; 232 } 233 } 234 } 235 } 236 237 ConcurrentMap<ImmutableByteArray, Long> getOrCreateLowestSequenceIds(byte[] encodedRegionName) { 238 // Intentionally, this access is done outside of this.regionSequenceIdLock. Done per append. 239 return computeIfAbsent(this.lowestUnflushedSequenceIds, encodedRegionName, 240 ConcurrentHashMap::new); 241 } 242 243 /** 244 * @param sequenceids Map to search for lowest value. 245 * @return Lowest value found in <code>sequenceids</code>. 246 */ 247 private static long getLowestSequenceId(Map<?, Long> sequenceids) { 248 long lowest = HConstants.NO_SEQNUM; 249 for (Map.Entry<?, Long> entry : sequenceids.entrySet()) { 250 if (entry.getKey().toString().equals("METAFAMILY")) { 251 continue; 252 } 253 Long sid = entry.getValue(); 254 if (lowest == HConstants.NO_SEQNUM || sid.longValue() < lowest) { 255 lowest = sid.longValue(); 256 } 257 } 258 return lowest; 259 } 260 261 /** 262 * n * @return New Map that has same keys as <code>src</code> but instead of a Map for a value, it 263 * instead has found the smallest sequence id and it returns that as the value instead. 264 */ 265 private <T extends Map<?, Long>> Map<byte[], Long> flattenToLowestSequenceId(Map<byte[], T> src) { 266 if (src == null || src.isEmpty()) { 267 return null; 268 } 269 Map<byte[], Long> tgt = new HashMap<>(); 270 for (Map.Entry<byte[], T> entry : src.entrySet()) { 271 long lowestSeqId = getLowestSequenceId(entry.getValue()); 272 if (lowestSeqId != HConstants.NO_SEQNUM) { 273 tgt.put(entry.getKey(), lowestSeqId); 274 } 275 } 276 return tgt; 277 } 278 279 /** 280 * @param encodedRegionName Region to flush. 281 * @param families Families to flush. May be a subset of all families in the region. 282 * @return Returns {@link HConstants#NO_SEQNUM} if we are flushing the whole region OR if we are 283 * flushing a subset of all families but there are no edits in those families not being 284 * flushed; in other words, this is effectively same as a flush of all of the region 285 * though we were passed a subset of regions. Otherwise, it returns the sequence id of the 286 * oldest/lowest outstanding edit. 287 */ 288 Long startCacheFlush(final byte[] encodedRegionName, final Set<byte[]> families) { 289 Map<byte[], Long> familytoSeq = new HashMap<>(); 290 for (byte[] familyName : families) { 291 familytoSeq.put(familyName, HConstants.NO_SEQNUM); 292 } 293 return startCacheFlush(encodedRegionName, familytoSeq); 294 } 295 296 Long startCacheFlush(final byte[] encodedRegionName, final Map<byte[], Long> familyToSeq) { 297 Map<ImmutableByteArray, Long> oldSequenceIds = null; 298 Long lowestUnflushedInRegion = HConstants.NO_SEQNUM; 299 synchronized (tieLock) { 300 Map<ImmutableByteArray, Long> m = this.lowestUnflushedSequenceIds.get(encodedRegionName); 301 if (m != null) { 302 // NOTE: Removal from this.lowestUnflushedSequenceIds must be done in controlled 303 // circumstance because another concurrent thread now may add sequenceids for this family 304 // (see above in getOrCreateLowestSequenceId). Make sure you are ok with this. Usually it 305 // is fine because updates are blocked when this method is called. Make sure!!! 306 for (Map.Entry<byte[], Long> entry : familyToSeq.entrySet()) { 307 ImmutableByteArray familyNameWrapper = ImmutableByteArray.wrap((byte[]) entry.getKey()); 308 Long seqId = null; 309 if (entry.getValue() == HConstants.NO_SEQNUM) { 310 seqId = m.remove(familyNameWrapper); 311 } else { 312 seqId = m.replace(familyNameWrapper, entry.getValue()); 313 } 314 if (seqId != null) { 315 if (oldSequenceIds == null) { 316 oldSequenceIds = new HashMap<>(); 317 } 318 oldSequenceIds.put(familyNameWrapper, seqId); 319 } 320 } 321 if (oldSequenceIds != null && !oldSequenceIds.isEmpty()) { 322 if (this.flushingSequenceIds.put(encodedRegionName, oldSequenceIds) != null) { 323 LOG.warn("Flushing Map not cleaned up for " + Bytes.toString(encodedRegionName) 324 + ", sequenceid=" + oldSequenceIds); 325 } 326 } 327 if (m.isEmpty()) { 328 // Remove it otherwise it will be in oldestUnflushedStoreSequenceIds for ever 329 // even if the region is already moved to other server. 330 // Do not worry about data racing, we held write lock of region when calling 331 // startCacheFlush, so no one can add value to the map we removed. 332 this.lowestUnflushedSequenceIds.remove(encodedRegionName); 333 } else { 334 // Flushing a subset of the region families. Return the sequence id of the oldest entry. 335 lowestUnflushedInRegion = Collections.min(m.values()); 336 } 337 } 338 } 339 // Do this check outside lock. 340 if (oldSequenceIds != null && oldSequenceIds.isEmpty()) { 341 // TODO: if we have no oldStoreSeqNum, and WAL is not disabled, presumably either 342 // the region is already flushing (which would make this call invalid), or there 343 // were no appends after last flush, so why are we starting flush? Maybe we should 344 // assert not empty. Less rigorous, but safer, alternative is telling the caller to stop. 345 // For now preserve old logic. 346 LOG.warn("Couldn't find oldest sequenceid for " + Bytes.toString(encodedRegionName)); 347 } 348 return lowestUnflushedInRegion; 349 } 350 351 void completeCacheFlush(byte[] encodedRegionName, long maxFlushedSeqId) { 352 // This is a simple hack to avoid maxFlushedSeqId go backwards. 353 // The system works fine normally, but if we make use of Durability.ASYNC_WAL and we are going 354 // to flush all the stores, the maxFlushedSeqId will be next seq id of the region, but we may 355 // still have some unsynced WAL entries in the ringbuffer after we call startCacheFlush, and 356 // then it will be recorded as the lowestUnflushedSeqId by the above update method, which is 357 // less than the current maxFlushedSeqId. And if next time we only flush the family with this 358 // unusual lowestUnflushedSeqId, the maxFlushedSeqId will go backwards. 359 // This is an unexpected behavior so we should fix it, otherwise it may cause unexpected 360 // behavior in other area. 361 // The solution here is a bit hack but fine. Just replace the lowestUnflushedSeqId with 362 // maxFlushedSeqId + 1 if it is lesser. The meaning of maxFlushedSeqId is that, all edits less 363 // than or equal to it have been flushed, i.e, persistent to HFile, so set 364 // lowestUnflushedSequenceId to maxFlushedSeqId + 1 will not cause data loss. 365 // And technically, using +1 is fine here. If the maxFlushesSeqId is just the flushOpSeqId, it 366 // means we have flushed all the stores so the seq id for actual data should be at least plus 1. 367 // And if we do not flush all the stores, then the maxFlushedSeqId is calculated by 368 // lowestUnflushedSeqId - 1, so here let's plus the 1 back. 369 Long wrappedSeqId = Long.valueOf(maxFlushedSeqId + 1); 370 synchronized (tieLock) { 371 this.flushingSequenceIds.remove(encodedRegionName); 372 Map<ImmutableByteArray, Long> unflushed = lowestUnflushedSequenceIds.get(encodedRegionName); 373 if (unflushed == null) { 374 return; 375 } 376 for (Map.Entry<ImmutableByteArray, Long> e : unflushed.entrySet()) { 377 if (e.getValue().longValue() <= maxFlushedSeqId) { 378 e.setValue(wrappedSeqId); 379 } 380 } 381 } 382 } 383 384 void abortCacheFlush(final byte[] encodedRegionName) { 385 // Method is called when we are crashing down because failed write flush AND it is called 386 // if we fail prepare. The below is for the fail prepare case; we restore the old sequence ids. 387 Map<ImmutableByteArray, Long> flushing = null; 388 Map<ImmutableByteArray, Long> tmpMap = new HashMap<>(); 389 // Here we are moving sequenceids from flushing back to unflushed; doing opposite of what 390 // happened in startCacheFlush. During prepare phase, we have update lock on the region so 391 // no edits should be coming in via append. 392 synchronized (tieLock) { 393 flushing = this.flushingSequenceIds.remove(encodedRegionName); 394 if (flushing != null) { 395 Map<ImmutableByteArray, Long> unflushed = getOrCreateLowestSequenceIds(encodedRegionName); 396 for (Map.Entry<ImmutableByteArray, Long> e : flushing.entrySet()) { 397 // Set into unflushed the 'old' oldest sequenceid and if any value in flushed with this 398 // value, it will now be in tmpMap. 399 tmpMap.put(e.getKey(), unflushed.put(e.getKey(), e.getValue())); 400 } 401 } 402 } 403 404 // Here we are doing some 'test' to see if edits are going in out of order. What is it for? 405 // Carried over from old code. 406 if (flushing != null) { 407 for (Map.Entry<ImmutableByteArray, Long> e : flushing.entrySet()) { 408 Long currentId = tmpMap.get(e.getKey()); 409 if (currentId != null && currentId.longValue() < e.getValue().longValue()) { 410 String errorStr = Bytes.toString(encodedRegionName) + " family " + e.getKey().toString() 411 + " acquired edits out of order current memstore seq=" + currentId 412 + ", previous oldest unflushed id=" + e.getValue(); 413 LOG.error(errorStr); 414 Runtime.getRuntime().halt(1); 415 } 416 } 417 } 418 } 419 420 /** 421 * See if passed <code>sequenceids</code> are lower -- i.e. earlier -- than any outstanding 422 * sequenceids, sequenceids we are holding on to in this accounting instance. 423 * @param sequenceids Keyed by encoded region name. Cannot be null (doesn't make sense for it to 424 * be null). 425 * @return true if all sequenceids are lower, older than, the old sequenceids in this instance. 426 */ 427 boolean areAllLower(Map<byte[], Long> sequenceids) { 428 Map<byte[], Long> flushing = null; 429 Map<byte[], Long> unflushed = null; 430 synchronized (this.tieLock) { 431 // Get a flattened -- only the oldest sequenceid -- copy of current flushing and unflushed 432 // data structures to use in tests below. 433 flushing = flattenToLowestSequenceId(this.flushingSequenceIds); 434 unflushed = flattenToLowestSequenceId(this.lowestUnflushedSequenceIds); 435 } 436 for (Map.Entry<byte[], Long> e : sequenceids.entrySet()) { 437 long oldestFlushing = Long.MAX_VALUE; 438 long oldestUnflushed = Long.MAX_VALUE; 439 if (flushing != null && flushing.containsKey(e.getKey())) { 440 oldestFlushing = flushing.get(e.getKey()); 441 } 442 if (unflushed != null && unflushed.containsKey(e.getKey())) { 443 oldestUnflushed = unflushed.get(e.getKey()); 444 } 445 long min = Math.min(oldestFlushing, oldestUnflushed); 446 if (min <= e.getValue()) { 447 return false; 448 } 449 } 450 return true; 451 } 452 453 /** 454 * Iterates over the given Map and compares sequence ids with corresponding entries in 455 * {@link #lowestUnflushedSequenceIds}. If a region in {@link #lowestUnflushedSequenceIds} has a 456 * sequence id less than that passed in <code>sequenceids</code> then return it. 457 * @param sequenceids Sequenceids keyed by encoded region name. 458 * @return stores of regions found in this instance with sequence ids less than those passed in. 459 */ 460 Map<byte[], List<byte[]>> findLower(Map<byte[], Long> sequenceids) { 461 Map<byte[], List<byte[]>> toFlush = null; 462 // Keeping the old behavior of iterating unflushedSeqNums under oldestSeqNumsLock. 463 synchronized (tieLock) { 464 for (Map.Entry<byte[], Long> e : sequenceids.entrySet()) { 465 Map<ImmutableByteArray, Long> m = this.lowestUnflushedSequenceIds.get(e.getKey()); 466 if (m == null) { 467 continue; 468 } 469 for (Map.Entry<ImmutableByteArray, Long> me : m.entrySet()) { 470 if (me.getValue() <= e.getValue()) { 471 if (toFlush == null) { 472 toFlush = new TreeMap(Bytes.BYTES_COMPARATOR); 473 } 474 toFlush.computeIfAbsent(e.getKey(), k -> new ArrayList<>()) 475 .add(Bytes.toBytes(me.getKey().toString())); 476 } 477 } 478 } 479 } 480 return toFlush; 481 } 482}