Github user khurrumnasimm commented on a diff in the pull request:
https://github.com/apache/incubator-distributedlog/pull/42#discussion_r86109926
--- Diff:
distributedlog-core/src/main/java/com/twitter/distributedlog/BKSyncLogReaderDLSN.java
---
@@ -116,7 +110,7 @@ public void resumeReadAhead() {
@Override
public void onSuccess(LogRecordWithDLSN record) {
- setLastSeenDLSN(record.getDlsn());
+ this.lastSeenDLSN = record.getDlsn();
--- End diff --
Are you referring this code below? lastDLSNSeenByReadAhead is a local
variable and the lastSeenDLSN is a volatile variable. The visibility and the
ordering of a volatile variable is guaranteed by java - that says accessing the
lastSeenDLSN will retrieve the latest value, hence no atomicity is required
here.
` // if last seen DLSN by reader is same as the one
seen by ReadAhead
// that means that reader is caught up with
ReadAhead and ReadAhead
// is caught up with stream
shallWait = DLSN.InitialDLSN !=
lastDLSNSeenByReadAhead
&&
lastSeenDLSN.compareTo(lastDLSNSeenByReadAhead) < 0
&&
startDLSN.compareTo(lastDLSNSeenByReadAhead) <= 0;`
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