[GitHub] [bookkeeper] StevenLuMT commented on a diff in pull request #3378: remove writeCacheRotationLock when insert writeCache

[GitBox <gi...@apache.org>]

StevenLuMT commented on code in PR #3378:
URL: https://github.com/apache/bookkeeper/pull/3378#discussion_r926911566


##########
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java:
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@@ -401,24 +401,7 @@ public long addEntry(ByteBuf entry) throws IOException, BookieException {
             log.debug("Add entry. {}@{}, lac = {}", ledgerId, entryId, lac);
         }
 
-        // First we try to do an optimistic locking to get access to the current write cache.
-        // This is based on the fact that the write cache is only being rotated (swapped) every 1 minute. During the
-        // rest of the time, we can have multiple thread using the optimistic lock here without interfering.
-        long stamp = writeCacheRotationLock.tryOptimisticRead();
-        boolean inserted = false;
-
-        inserted = writeCache.put(ledgerId, entryId, entry);
-        if (!writeCacheRotationLock.validate(stamp)) {
-            // The write cache was rotated while we were inserting. We need to acquire the proper read lock and repeat
-            // the operation because we might have inserted in a write cache that was already being flushed and cleared,
-            // without being sure about this last entry being flushed or not.
-            stamp = writeCacheRotationLock.readLock();
-            try {
-                inserted = writeCache.put(ledgerId, entryId, entry);
-            } finally {
-                writeCacheRotationLock.unlockRead(stamp);
-            }
-        }
+       boolean inserted = writeCache.put(ledgerId, entryId, entry);

Review Comment:
   @eolivelli @lordcheng10
   I think this lock is necessary 
   when swapWriteCache cost long time, during this time, writeCacheRotationLock.writeLock takes effect 
   we need to care this action, block writeCache's put action, prevent more write pressure on writecache



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