ohadshacham commented on a change in pull request #59: [OMID-146] Fix
consistensy of compaction when the commit time stamp has…
URL: https://github.com/apache/incubator-omid/pull/59#discussion_r277984747
##########
File path:
hbase-coprocessor/src/main/java/org/apache/omid/transaction/CompactorScanner.java
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@@ -228,43 +228,90 @@ private long getLowWatermarkFromCommitTable() throws
IOException {
}
}
- private Optional<CommitTimestamp> queryCommitTimestamp(Cell cell) throws
IOException {
- Optional<CommitTimestamp> cachedValue =
commitCache.get(cell.getTimestamp());
- if (cachedValue != null) {
- return cachedValue;
- }
+
+ private Result getShadowCell(byte[] row, byte[] family, byte[] qualifier,
long timestamp) throws IOException {
+ Get g = new Get(row);
+ g.addColumn(family, qualifier);
+ g.setTimeStamp(timestamp);
+ Result r = hRegion.get(g);
+ return r;
+ }
+
+
+ private Optional<CommitTimestamp> getCommitTimestampWithRaces(Cell cell)
throws IOException {
try {
+ byte[] family = CellUtil.cloneFamily(cell);
+ byte[] qualifier =
CellUtils.addShadowCellSuffixPrefix(cell.getQualifierArray(),
+ cell.getQualifierOffset(),
+ cell.getQualifierLength());
+ // 2) Then check the commit table
Optional<CommitTimestamp> ct =
commitTableClient.getCommitTimestamp(cell.getTimestamp()).get();
if (ct.isPresent()) {
- commitCache.put(cell.getTimestamp(), ct);
- return Optional.of(ct.get());
- } else {
- Get g = new Get(CellUtil.cloneRow(cell));
- byte[] family = CellUtil.cloneFamily(cell);
- byte[] qualifier =
CellUtils.addShadowCellSuffixPrefix(cell.getQualifierArray(),
- cell.getQualifierOffset(),
- cell.getQualifierLength());
- g.addColumn(family, qualifier);
- g.setTimeStamp(cell.getTimestamp());
- Result r = hRegion.get(g);
- if (r.containsColumn(family, qualifier)) {
+ if (ct.get().isValid()) {
+ return Optional.of(ct.get());
+ }
+ // If invalid still should check sc because maybe we are in
lowlatency mode.
+ }
+
+ // 3) Read from shadow cell
+ Result r = getShadowCell(CellUtil.cloneRow(cell), family,
qualifier, cell.getTimestamp());
+ if (r.containsColumn(CellUtil.cloneFamily(cell), qualifier)) {
+ Optional<CommitTimestamp> retval = Optional.of(new
CommitTimestamp(SHADOW_CELL,
+ Bytes.toLong(r.getValue(family, qualifier)), true));
+ return retval;
+ }
+
+ // [OMID-146] - we have to invalidate a transaction if it hasn't
reached the commit table
+ // 4) invalidate the entry
+ Boolean invalidated =
commitTableClient.tryInvalidateTransaction(cell.getTimestamp()).get();
+ if (invalidated) {
+ // If we are running lowLatency Omid, we could have manged to
invalidate a ct entry,
+ // but the committing client already wrote to shadow cells:
+ Result r2 = getShadowCell(CellUtil.cloneRow(cell), family,
qualifier, cell.getTimestamp());
+ if (r2.containsColumn(CellUtil.cloneFamily(cell), qualifier)) {
Optional<CommitTimestamp> retval = Optional.of(new
CommitTimestamp(SHADOW_CELL,
- Bytes.toLong(r.getValue(family, qualifier)),
true));
- commitCache.put(cell.getTimestamp(), retval);
+ Bytes.toLong(r2.getValue(family, qualifier)),
true));
return retval;
-
}
+ return Optional.absent();
+ }
+
+ // 5) We did not manage to invalidate the transactions then check
the commit table
+ Optional<CommitTimestamp> ct2 =
commitTableClient.getCommitTimestamp(cell.getTimestamp()).get();
+ if (ct2.isPresent()) {
+ return Optional.of(ct2.get());
Review comment:
Shouldn't we check "if (ct.get().isValid()) {" and return absent in case it
is not? under the "if (ct2.isPresent()) {".
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