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Clarify global checkpoint recovery #21934

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Merged
merged 2 commits into from
Dec 2, 2016
Merged

Clarify global checkpoint recovery #21934

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6e5429f
Clarify global checkpoint recovery
jasontedor Dec 2, 2016
7a48c39
Simplify trace logging statement in InternalEngine
jasontedor Dec 2, 2016
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84 changes: 57 additions & 27 deletions core/src/main/java/org/elasticsearch/index/engine/InternalEngine.java
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Original file line number Diff line number Diff line change
Expand Up @@ -154,23 +154,33 @@ public InternalEngine(EngineConfig engineConfig) throws EngineException {
throttle = new IndexThrottle();
this.searcherFactory = new SearchFactory(logger, isClosed, engineConfig);
try {
writer = createWriter(openMode == EngineConfig.OpenMode.CREATE_INDEX_AND_TRANSLOG);
final SeqNoStats seqNoStats = loadSeqNoStats(engineConfig, writer);
if (logger.isTraceEnabled()) {
logger.trace(
"recovering max sequence number: [{}], local checkpoint: [{}], global checkpoint: [{}]",
seqNoStats.getMaxSeqNo(),
seqNoStats.getLocalCheckpoint(),
seqNoStats.getGlobalCheckpoint());
final SeqNoStats seqNoStats;
switch (openMode) {
case OPEN_INDEX_AND_TRANSLOG:
writer = createWriter(false);
seqNoStats = loadSeqNoStatsFromLuceneAndTranslog(engineConfig.getTranslogConfig(), writer);
break;
case OPEN_INDEX_CREATE_TRANSLOG:
writer = createWriter(false);
seqNoStats = loadSeqNoStatsLucene(SequenceNumbersService.UNASSIGNED_SEQ_NO, writer);
break;
case CREATE_INDEX_AND_TRANSLOG:
writer = createWriter(true);
seqNoStats = new SeqNoStats(
SequenceNumbersService.NO_OPS_PERFORMED,
SequenceNumbersService.NO_OPS_PERFORMED,
SequenceNumbersService.UNASSIGNED_SEQ_NO);
break;
default:
throw new IllegalArgumentException(openMode.toString());
}
seqNoService =
new SequenceNumbersService(
shardId,
engineConfig.getIndexSettings(),
seqNoStats.getMaxSeqNo(),
seqNoStats.getLocalCheckpoint(),
seqNoStats.getGlobalCheckpoint());
logger.trace(
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@bleskes bleskes Dec 2, 2016

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nit: seqNoStats has a toString - just use it and be safe?

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@jasontedor jasontedor Dec 2, 2016

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I pushed 7a48c39.

"recovered max sequence number: [{}], local checkpoint: [{}], global checkpoint: [{}]",
seqNoStats.getMaxSeqNo(),
seqNoStats.getLocalCheckpoint(),
seqNoStats.getGlobalCheckpoint());
indexWriter = writer;
seqNoService = sequenceNumberService(shardId, engineConfig.getIndexSettings(), seqNoStats);
translog = openTranslog(engineConfig, writer, seqNoService::getGlobalCheckpoint);
assert translog.getGeneration() != null;
} catch (IOException | TranslogCorruptedException e) {
Expand Down Expand Up @@ -209,6 +219,18 @@ public InternalEngine(EngineConfig engineConfig) throws EngineException {
logger.trace("created new InternalEngine");
}

private static SequenceNumbersService sequenceNumberService(
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@bleskes bleskes Dec 2, 2016

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this is what you get from the crazy syntax 👅

final ShardId shardId,
final IndexSettings indexSettings,
final SeqNoStats seqNoStats) {
return new SequenceNumbersService(
shardId,
indexSettings,
seqNoStats.getMaxSeqNo(),
seqNoStats.getLocalCheckpoint(),
seqNoStats.getGlobalCheckpoint());
}

@Override
public InternalEngine recoverFromTranslog() throws IOException {
flushLock.lock();
Expand Down Expand Up @@ -326,18 +348,33 @@ private Translog.TranslogGeneration loadTranslogIdFromCommit(IndexWriter writer)
}

/**
* Reads the sequence number stats from the Lucene commit point (maximum sequence number and local checkpoint) and the Translog
* Reads the sequence number stats from the Lucene commit point (maximum sequence number and local checkpoint) and the translog
* checkpoint (global checkpoint).
*
* @param engineConfig the engine configuration (for the open mode and the translog path)
* @param writer the index writer (for the Lucene commit point)
* @param translogConfig the translog config (for the global checkpoint)
* @param indexWriter the index writer (for the Lucene commit point)
* @return the sequence number stats
* @throws IOException if an I/O exception occurred reading the Lucene commit point or the translog checkpoint
*/
private static SeqNoStats loadSeqNoStats(final EngineConfig engineConfig, final IndexWriter writer) throws IOException {
private static SeqNoStats loadSeqNoStatsFromLuceneAndTranslog(
final TranslogConfig translogConfig,
final IndexWriter indexWriter) throws IOException {
long globalCheckpoint = Translog.readGlobalCheckpoint(translogConfig.getTranslogPath());
return loadSeqNoStatsLucene(globalCheckpoint, indexWriter);
}

/**
* Reads the sequence number stats from the Lucene commit point (maximum sequence number and local checkpoint) and uses the
* specified global checkpoint.
*
* @param globalCheckpoint the global checkpoint to use
* @param indexWriter the index writer (for the Lucene commit point)
* @return the sequence number stats
*/
private static SeqNoStats loadSeqNoStatsLucene(final long globalCheckpoint, final IndexWriter indexWriter) {
long maxSeqNo = SequenceNumbersService.NO_OPS_PERFORMED;
long localCheckpoint = SequenceNumbersService.NO_OPS_PERFORMED;
for (Map.Entry<String, String> entry : writer.getLiveCommitData()) {
for (Map.Entry<String, String> entry : indexWriter.getLiveCommitData()) {
final String key = entry.getKey();
if (key.equals(LOCAL_CHECKPOINT_KEY)) {
assert localCheckpoint == SequenceNumbersService.NO_OPS_PERFORMED;
Expand All @@ -348,13 +385,6 @@ private static SeqNoStats loadSeqNoStats(final EngineConfig engineConfig, final
}
}

final long globalCheckpoint;
if (engineConfig.getOpenMode() == EngineConfig.OpenMode.OPEN_INDEX_AND_TRANSLOG) {
globalCheckpoint = Translog.readGlobalCheckpoint(engineConfig.getTranslogConfig().getTranslogPath());
} else {
globalCheckpoint = SequenceNumbersService.UNASSIGNED_SEQ_NO;
}

return new SeqNoStats(maxSeqNo, localCheckpoint, globalCheckpoint);
}

Expand Down