[GitHub] [bookkeeper] dlg99 commented on a diff in pull request #3342: Bookie cache optimization

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

dlg99 commented on code in PR #3342:
URL: https://github.com/apache/bookkeeper/pull/3342#discussion_r902850722


##########
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java:
##########
@@ -191,8 +204,10 @@ public SingleDirectoryDbLedgerStorage(ServerConfiguration conf, LedgerManager le
 
         dbLedgerStorageStats = new DbLedgerStorageStats(
                 ledgerDirStatsLogger,
-            () -> writeCache.size() + writeCacheBeingFlushed.size(),
-            () -> writeCache.count() + writeCacheBeingFlushed.count(),
+            () -> this.isWriteCacheFixedLengthEnabled ? writeCache.size() + writeCacheBeingFlushed.size()
+                    + writeCacheLastFlushed.size() : writeCache.size() + writeCacheBeingFlushed.size(),
+            () -> this.isWriteCacheFixedLengthEnabled ? writeCache.count() + writeCacheBeingFlushed.count()
+                    + writeCacheLastFlushed.count() : writeCache.count() + writeCacheBeingFlushed.count(),

Review Comment:
   ```suggestion
               this.isWriteCacheFixedLengthEnabled ? () ->  writeCache.size() + writeCacheBeingFlushed.size()
                       + writeCacheLastFlushed.size() : () -> writeCache.size() + writeCacheBeingFlushed.size(),
               this.isWriteCacheFixedLengthEnabled ? () -> writeCache.count() + writeCacheBeingFlushed.count()
                       + writeCacheLastFlushed.count() : () -> writeCache.count() + writeCacheBeingFlushed.count(),
   ```
   in this case you don't have to check for isWriteCacheFixedLengthEnabled / isWriteCacheFixedLengthEnabled inside lambdas, these won't change dynamically as I understand



##########
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/SingleDirectoryDbLedgerStorage.java:
##########
@@ -793,6 +843,13 @@ public void checkpoint(Checkpoint checkpoint) throws IOException {
         }
     }
 
+    private void cloneFlushedCache2LastFlushCache(WriteCache writeCacheBeingFlushed, WriteCache writeCacheLastFlushed) {
+        writeCacheLastFlushed.clear();
+        writeCacheBeingFlushed.forEach((ledgerId, entryId, data) -> {

Review Comment:
   this looks like an expensive operation. 
   Is there any reason to not swap two caches like in `swapWriteCache()`?



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