From 734126ef19dc16b3db8737dcc75db0a79889f5a0 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 16:28:04 +0800
Subject: [PATCH 01/13] add support for specifying LengthToRead.

---
 .../bookkeeper/bookie/DefaultEntryLogger.java | 29 +++++++++++++------
 .../bookkeeper/bookie/EntryLogCompactor.java  |  2 +-
 .../InterleavedStorageRegenerateIndexOp.java  |  7 ++++-
 .../TransactionalEntryLogCompactor.java       |  9 ++++--
 .../bookie/storage/EntryLogScanner.java       | 11 ++++++-
 .../directentrylogger/DirectEntryLogger.java  |  9 ++++--
 .../storage/ldb/LedgersIndexRebuildOp.java    |  7 ++++-
 .../storage/ldb/LocationsIndexRebuildOp.java  |  7 ++++-
 .../cli/commands/bookie/ReadLogCommand.java   |  7 ++---
 9 files changed, 66 insertions(+), 22 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index 575a8b375e3..64d74b0faac 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -1036,15 +1036,20 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                 }
                 // read the entry
                 data.clear();
-                data.capacity(entrySize);
-                int rc = readFromLogChannel(entryLogId, bc, data, pos);
-                if (rc != entrySize) {
-                    LOG.warn("Short read for ledger entry from entryLog {}@{} ({} != {})",
-                            entryLogId, pos, rc, entrySize);
-                    return;
+                int capacity = Math.min(scanner.getLengthToRead(), entrySize);
+                // skip read when scanner.getLengthToRead() == 0.
+                if (capacity > 0) {
+                    data.capacity(capacity);
+                    int rc = readFromLogChannel(entryLogId, bc, data, pos);
+                    if (rc != entrySize) {
+                        LOG.warn("Short read for ledger entry from entryLog {}@{} ({} != {})",
+                                entryLogId, pos, rc, entrySize);
+                        return;
+                    }
                 }
+
                 // process the entry
-                scanner.process(ledgerId, offset, data);
+                scanner.process(ledgerId, offset, data, entrySize);
 
                 // Advance position to the next entry
                 pos += entrySize;
@@ -1164,18 +1169,24 @@ private EntryLogMetadata extractEntryLogMetadataByScanning(long entryLogId,
         // Read through the entry log file and extract the entry log meta
         scanEntryLog(entryLogId, new EntryLogScanner() {
             @Override
-            public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+            public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                 if (throttler != null) {
                     throttler.acquire(entry.readableBytes());
                 }
                 // add new entry size of a ledger to entry log meta
-                meta.addLedgerSize(ledgerId, entry.readableBytes() + 4);
+                meta.addLedgerSize(ledgerId, entrySize + 4);
             }
 
             @Override
             public boolean accept(long ledgerId) {
                 return ledgerId >= 0;
             }
+
+            @Override
+            public int getLengthToRead(){
+                // we only need to read the entry size.
+                return EntryLogScanner.READ_NOTHING;
+            }
         });
 
         if (LOG.isDebugEnabled()) {
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
index 81cd463761a..c669b8e77d0 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
@@ -91,7 +91,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(final long ledgerId, long offset, ByteBuf entry) throws IOException {
+                public void process(final long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                     throttler.acquire(entry.readableBytes());
 
                     if (offsets.size() > maxOutstandingRequests) {
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index a05971a021f..ec90507fe74 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -114,7 +114,7 @@ public void initiate(boolean dryRun) throws IOException {
             LOG.info("Scanning {}", entryLogId);
             entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                     long entryId = entry.getLong(8);
 
                     stats.computeIfAbsent(ledgerId, (ignore) -> new RecoveryStats()).registerEntry(entryId);
@@ -138,6 +138,11 @@ public void process(long ledgerId, long offset, ByteBuf entry) throws IOExceptio
                 public boolean accept(long ledgerId) {
                     return ledgerIds.contains(ledgerId);
                 }
+
+                @Override
+                public int getLengthToRead() {
+                    return EntryLogScanner.READ_ENTRY_ID;
+                }
             });
 
             ledgerCache.flushLedger(true);
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index 2b6fca30c10..aba038ff357 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -169,7 +169,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                     throttler.acquire(entry.readableBytes());
                     synchronized (TransactionalEntryLogCompactor.this) {
                         long lid = entry.getLong(entry.readerIndex());
@@ -315,7 +315,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                     long lid = entry.getLong(entry.readerIndex());
                     long entryId = entry.getLong(entry.readerIndex() + 8);
                     if (lid != ledgerId || entryId < -1) {
@@ -327,6 +327,11 @@ public void process(long ledgerId, long offset, ByteBuf entry) throws IOExceptio
                     long location = (compactionLog.getDstLogId() << 32L) | (offset + 4);
                     offsets.add(new EntryLocation(lid, entryId, location));
                 }
+
+                @Override
+                public int getLengthToRead() {
+                    return EntryLogScanner.READ_LEDGER_ENTRY_ID
+                }
             });
             LOG.info("Recovered {} entry locations from compacted log {}", offsets.size(), compactionLog.getDstLogId());
         }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index 9305b6bef04..b7ff748c72d 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -27,6 +27,11 @@
  * Scan entries in a entry log file.
  */
 public interface EntryLogScanner {
+    public static final int READ_ALL = Integer.MAX_VALUE;
+    public static final int READ_NOTHING = 0;
+    public static final int READ_ENTRY_ID = 8;
+    public static final int READ_LEDGER_ENTRY_ID = 16;
+
     /**
      * Tests whether or not the entries belongs to the specified ledger
      * should be processed.
@@ -48,5 +53,9 @@ public interface EntryLogScanner {
      *          Entry ByteBuf
      * @throws IOException
      */
-    void process(long ledgerId, long offset, ByteBuf entry) throws IOException;
+    void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException;
+
+    default int getLengthToRead(){
+        return READ_ALL;
+    }
 }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
index 323727217d6..24f4a86d503 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
@@ -423,18 +423,23 @@ EntryLogMetadata scanEntryLogMetadata(long logId, AbstractLogCompactor.Throttler
         // Read through the entry log file and extract the entry log meta
         scanEntryLog(logId, new EntryLogScanner() {
             @Override
-            public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+            public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                 // add new entry size of a ledger to entry log meta
                 if (throttler != null) {
                     throttler.acquire(entry.readableBytes());
                 }
-                meta.addLedgerSize(ledgerId, entry.readableBytes() + Integer.BYTES);
+                meta.addLedgerSize(ledgerId, entrySize + Integer.BYTES);
             }
 
             @Override
             public boolean accept(long ledgerId) {
                 return ledgerId >= 0;
             }
+
+            @Override
+            public int getLengthToRead() {
+                return EntryLogScanner.READ_NOTHING;
+            }
         });
         return meta;
     }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
index 2725897e804..f166a9b1ea1 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
@@ -162,7 +162,7 @@ private void scanEntryLogFiles(Set<Long> ledgers, File[] lDirs) throws IOExcepti
         for (long entryLogId : entryLogs) {
             entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                     if (ledgers.add(ledgerId)) {
                         if (verbose) {
                             LOG.info("Found ledger {} in entry log", ledgerId);
@@ -174,6 +174,11 @@ public void process(long ledgerId, long offset, ByteBuf entry) throws IOExceptio
                 public boolean accept(long ledgerId) {
                     return true;
                 }
+
+                @Override
+                public int getLengthToRead() {
+                    return EntryLogScanner.READ_NOTHING;
+                }
             });
 
             ++completedEntryLogs;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index b9aaebec9e2..b64d904fb81 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -100,7 +100,7 @@ public void initiate() throws IOException {
             for (long entryLogId : entryLogs) {
                 entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                     @Override
-                    public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
+                    public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
                         long entryId = entry.getLong(8);
 
                         // Actual location indexed is pointing past the entry size
@@ -135,6 +135,11 @@ public void process(long ledgerId, long offset, ByteBuf entry) throws IOExceptio
                     public boolean accept(long ledgerId) {
                         return activeLedgers.contains(ledgerId);
                     }
+
+                    @Override
+                    public int getLengthToRead() {
+                        return EntryLogScanner.READ_ENTRY_ID;
+                    }
                 });
 
                 ++completedEntryLogs;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
index edef6609ff2..d44e491f06c 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
@@ -184,12 +184,11 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public void process(long ledgerId, long entryStartPos, ByteBuf entry) throws IOException {
+            public void process(long ledgerId, long entryStartPos, ByteBuf entry, int entrySize) throws IOException {
                 if (!stopScanning.booleanValue()) {
                     if ((rangeEndPos != -1) && (entryStartPos > rangeEndPos)) {
                         stopScanning.setValue(true);
                     } else {
-                        int entrySize = entry.readableBytes();
                         /**
                          * entrySize of an entry (inclusive of payload and
                          * header) value is stored as int value in log file, but
@@ -256,7 +255,7 @@ public boolean accept(long candidateLedgerId) {
             }
 
             @Override
-            public void process(long candidateLedgerId, long startPos, ByteBuf entry) {
+            public void process(long candidateLedgerId, long startPos, ByteBuf entry, int entrySize) {
                 long entrysLedgerId = entry.getLong(entry.readerIndex());
                 long entrysEntryId = entry.getLong(entry.readerIndex() + 8);
                 if ((candidateLedgerId == entrysLedgerId) && (candidateLedgerId == ledgerId)
@@ -289,7 +288,7 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public void process(long ledgerId, long startPos, ByteBuf entry) {
+            public void process(long ledgerId, long startPos, ByteBuf entry, int entrySize) {
                 FormatUtil.formatEntry(startPos, entry, printMsg, ledgerIdFormatter, entryFormatter);
             }
         });

From a9c6c78ff375dc0926685960a03a5e843fe91229 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 16:34:03 +0800
Subject: [PATCH 02/13] fix.

---
 .../bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java  | 2 +-
 .../bookkeeper/bookie/TransactionalEntryLogCompactor.java       | 2 +-
 .../org/apache/bookkeeper/bookie/storage/EntryLogScanner.java   | 1 -
 .../bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java  | 2 +-
 4 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index ec90507fe74..bf923edeac0 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -141,7 +141,7 @@ public boolean accept(long ledgerId) {
 
                 @Override
                 public int getLengthToRead() {
-                    return EntryLogScanner.READ_ENTRY_ID;
+                    return EntryLogScanner.READ_LEDGER_ENTRY_ID;
                 }
             });
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index aba038ff357..abc3b309cec 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -330,7 +330,7 @@ public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) th
 
                 @Override
                 public int getLengthToRead() {
-                    return EntryLogScanner.READ_LEDGER_ENTRY_ID
+                    return EntryLogScanner.READ_LEDGER_ENTRY_ID;
                 }
             });
             LOG.info("Recovered {} entry locations from compacted log {}", offsets.size(), compactionLog.getDstLogId());
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index b7ff748c72d..087f5e56409 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -29,7 +29,6 @@
 public interface EntryLogScanner {
     public static final int READ_ALL = Integer.MAX_VALUE;
     public static final int READ_NOTHING = 0;
-    public static final int READ_ENTRY_ID = 8;
     public static final int READ_LEDGER_ENTRY_ID = 16;
 
     /**
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index b64d904fb81..161161da130 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -138,7 +138,7 @@ public boolean accept(long ledgerId) {
 
                     @Override
                     public int getLengthToRead() {
-                        return EntryLogScanner.READ_ENTRY_ID;
+                        return EntryLogScanner.READ_LEDGER_ENTRY_ID;
                     }
                 });
 

From 7dc76893eece23dca0ac58dd2560291580cd5bd4 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 16:53:07 +0800
Subject: [PATCH 03/13] fix.

---
 .../bookie/storage/directentrylogger/LogReaderScan.java         | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
index 9718795143d..7a032f64e0d 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
@@ -51,7 +51,7 @@ static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner s
                 reader.readIntoBufferAt(entry, offset, entrySize);
                 long ledgerId = entry.getLong(0);
                 if (ledgerId >= 0 && scanner.accept(ledgerId)) {
-                    scanner.process(ledgerId, initOffset, entry);
+                    scanner.process(ledgerId, initOffset, entry, entrySize);
                 }
                 offset += entrySize;
             }

From 5c3823dcfdb9647d851f5001b07c1e5f2b43a84e Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 17:54:00 +0800
Subject: [PATCH 04/13] introduce enum ReadLengthType.

---
 .../bookkeeper/bookie/DefaultEntryLogger.java |  6 ++---
 .../InterleavedStorageRegenerateIndexOp.java  |  4 ++--
 .../TransactionalEntryLogCompactor.java       |  4 ++--
 .../bookie/storage/EntryLogScanner.java       | 24 +++++++++++++++----
 .../directentrylogger/DirectEntryLogger.java  |  4 ++--
 .../storage/ldb/LedgersIndexRebuildOp.java    |  4 ++--
 .../storage/ldb/LocationsIndexRebuildOp.java  |  4 ++--
 7 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index 64d74b0faac..afd1b59c1f7 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -1036,7 +1036,7 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                 }
                 // read the entry
                 data.clear();
-                int capacity = Math.min(scanner.getLengthToRead(), entrySize);
+                int capacity = Math.min(scanner.getLengthToRead().getLengthToRead(), entrySize);
                 // skip read when scanner.getLengthToRead() == 0.
                 if (capacity > 0) {
                     data.capacity(capacity);
@@ -1183,9 +1183,9 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public int getLengthToRead(){
+            public ReadLengthType getLengthToRead(){
                 // we only need to read the entry size.
-                return EntryLogScanner.READ_NOTHING;
+                return ReadLengthType.READ_NOTHING;
             }
         });
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index bf923edeac0..608aae92c04 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -140,8 +140,8 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public int getLengthToRead() {
-                    return EntryLogScanner.READ_LEDGER_ENTRY_ID;
+                public ReadLengthType getLengthToRead() {
+                    return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                 }
             });
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index abc3b309cec..9db2e45f370 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -329,8 +329,8 @@ public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) th
                 }
 
                 @Override
-                public int getLengthToRead() {
-                    return EntryLogScanner.READ_LEDGER_ENTRY_ID;
+                public ReadLengthType getLengthToRead() {
+                    return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                 }
             });
             LOG.info("Recovered {} entry locations from compacted log {}", offsets.size(), compactionLog.getDstLogId());
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index 087f5e56409..61179e3ae9c 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -27,9 +27,23 @@
  * Scan entries in a entry log file.
  */
 public interface EntryLogScanner {
-    public static final int READ_ALL = Integer.MAX_VALUE;
-    public static final int READ_NOTHING = 0;
-    public static final int READ_LEDGER_ENTRY_ID = 16;
+    enum ReadLengthType {
+        // Read all data of the entry
+        READ_ALL(Integer.MAX_VALUE),
+        // Read nothing of the entry
+        READ_NOTHING(0),
+        // Read ledger id(8 byte) and entry id(8 byte) in the beginning of the entry
+        READ_LEDGER_ENTRY_ID_LENGTH(16);
+
+        private final int lengthToRead;
+        ReadLengthType(int lengthToRead) {
+            this.lengthToRead = lengthToRead;
+        }
+
+        public int getLengthToRead() {
+            return lengthToRead;
+        }
+    }
 
     /**
      * Tests whether or not the entries belongs to the specified ledger
@@ -54,7 +68,7 @@ public interface EntryLogScanner {
      */
     void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException;
 
-    default int getLengthToRead(){
-        return READ_ALL;
+    default ReadLengthType getLengthToRead(){
+        return ReadLengthType.READ_ALL;
     }
 }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
index 24f4a86d503..5fdcc603813 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
@@ -437,8 +437,8 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public int getLengthToRead() {
-                return EntryLogScanner.READ_NOTHING;
+            public ReadLengthType getLengthToRead() {
+                return ReadLengthType.READ_NOTHING;
             }
         });
         return meta;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
index f166a9b1ea1..b36f6e0738d 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
@@ -176,8 +176,8 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public int getLengthToRead() {
-                    return EntryLogScanner.READ_NOTHING;
+                public ReadLengthType getLengthToRead() {
+                    return ReadLengthType.READ_NOTHING;
                 }
             });
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index 161161da130..178070927a8 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -137,8 +137,8 @@ public boolean accept(long ledgerId) {
                     }
 
                     @Override
-                    public int getLengthToRead() {
-                        return EntryLogScanner.READ_LEDGER_ENTRY_ID;
+                    public ReadLengthType getLengthToRead() {
+                        return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                     }
                 });
 

From 4aa6134050a5ef4e7d122a3071e69aa9b5145f8d Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 18:21:36 +0800
Subject: [PATCH 05/13] introduce different process method.

---
 .../bookkeeper/bookie/DefaultEntryLogger.java |  5 +--
 .../InterleavedStorageRegenerateIndexOp.java  |  4 +--
 .../TransactionalEntryLogCompactor.java       | 13 +++----
 .../bookie/storage/EntryLogScanner.java       | 36 +++++++++++++------
 .../directentrylogger/DirectEntryLogger.java  |  5 +--
 .../storage/ldb/LedgersIndexRebuildOp.java    |  2 +-
 .../storage/ldb/LocationsIndexRebuildOp.java  |  4 +--
 7 files changed, 35 insertions(+), 34 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index afd1b59c1f7..bb6b462ccbb 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -1169,10 +1169,7 @@ private EntryLogMetadata extractEntryLogMetadataByScanning(long entryLogId,
         // Read through the entry log file and extract the entry log meta
         scanEntryLog(entryLogId, new EntryLogScanner() {
             @Override
-            public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
-                if (throttler != null) {
-                    throttler.acquire(entry.readableBytes());
-                }
+            public void process(long ledgerId, long offset, int entrySize) throws IOException {
                 // add new entry size of a ledger to entry log meta
                 meta.addLedgerSize(ledgerId, entrySize + 4);
             }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index 608aae92c04..c19a9075abe 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -114,9 +114,7 @@ public void initiate(boolean dryRun) throws IOException {
             LOG.info("Scanning {}", entryLogId);
             entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
-                    long entryId = entry.getLong(8);
-
+                public void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {
                     stats.computeIfAbsent(ledgerId, (ignore) -> new RecoveryStats()).registerEntry(entryId);
 
                     // Actual location indexed is pointing past the entry size
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index 9db2e45f370..0a59a76caf5 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -315,17 +315,14 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
-                    long lid = entry.getLong(entry.readerIndex());
-                    long entryId = entry.getLong(entry.readerIndex() + 8);
-                    if (lid != ledgerId || entryId < -1) {
-                        LOG.warn("Scanning expected ledgerId {}, but found invalid entry "
-                                + "with ledgerId {} entryId {} at offset {}",
-                                ledgerId, lid, entryId, offset);
+                public void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {
+                    if (entryId < -1) {
+                        LOG.warn("Scanning found invalid entry with ledgerId {} entryId {} at offset {}",
+                                ledgerId, entryId, offset);
                         throw new IOException("Invalid entry found @ offset " + offset);
                     }
                     long location = (compactionLog.getDstLogId() << 32L) | (offset + 4);
-                    offsets.add(new EntryLocation(lid, entryId, location));
+                    offsets.add(new EntryLocation(ledgerId, entryId, location));
                 }
 
                 @Override
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index 61179e3ae9c..2d8e738f1ec 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -49,24 +49,38 @@ public int getLengthToRead() {
      * Tests whether or not the entries belongs to the specified ledger
      * should be processed.
      *
-     * @param ledgerId
-     *          Ledger ID.
+     * @param ledgerId ledger id
      * @return true if and only the entries of the ledger should be scanned.
      */
     boolean accept(long ledgerId);
 
     /**
-     * Process an entry.
-     *
-     * @param ledgerId
-     *          Ledger ID.
-     * @param offset
-     *          File offset of this entry.
-     * @param entry
-     *          Entry ByteBuf
+     * Process an entry when ReadLengthType is READ_NOTHING.
+     * @param ledgerId ledger id
+     * @param entrySize entry size
+     * @throws IOException
+     */
+    default void process(long ledgerId, long offset, int entrySize) throws IOException {}
+
+    /**
+     * Process an entry when ReadLengthType is READ_LEDGER_ENTRY_ID_LENGTH.
+     * @param ledgerId ledger id
+     * @param offset offset of the entry
+     * @param entrySize entry size
+     * @param entryId entry id
      * @throws IOException
      */
-    void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException;
+    default void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {}
+
+    /**
+     * Process an entry when ReadLengthType is READ_ALL.
+     * @param ledgerId ledger id
+     * @param offset offset of the entry
+     * @param entry entry
+     * @param entrySize entry size
+     */
+    default void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException{}
+
 
     default ReadLengthType getLengthToRead(){
         return ReadLengthType.READ_ALL;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
index 5fdcc603813..7758bcd9720 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
@@ -423,11 +423,8 @@ EntryLogMetadata scanEntryLogMetadata(long logId, AbstractLogCompactor.Throttler
         // Read through the entry log file and extract the entry log meta
         scanEntryLog(logId, new EntryLogScanner() {
             @Override
-            public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
+            public void process(long ledgerId, long offset, int entrySize) throws IOException {
                 // add new entry size of a ledger to entry log meta
-                if (throttler != null) {
-                    throttler.acquire(entry.readableBytes());
-                }
                 meta.addLedgerSize(ledgerId, entrySize + Integer.BYTES);
             }
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
index b36f6e0738d..d3636c0a78b 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
@@ -162,7 +162,7 @@ private void scanEntryLogFiles(Set<Long> ledgers, File[] lDirs) throws IOExcepti
         for (long entryLogId : entryLogs) {
             entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
+                public void process(long ledgerId, long offset, int entrySize) throws IOException {
                     if (ledgers.add(ledgerId)) {
                         if (verbose) {
                             LOG.info("Found ledger {} in entry log", ledgerId);
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index 178070927a8..7b86213427b 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -100,9 +100,7 @@ public void initiate() throws IOException {
             for (long entryLogId : entryLogs) {
                 entryLogger.scanEntryLog(entryLogId, new EntryLogScanner() {
                     @Override
-                    public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
-                        long entryId = entry.getLong(8);
-
+                    public void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {
                         // Actual location indexed is pointing past the entry size
                         long location = (entryLogId << 32L) | (offset + 4);
 

From 2d4b70087069c92037ce3bc944f315e93d102210 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:01:57 +0800
Subject: [PATCH 06/13] refactor.

---
 .../bookkeeper/bookie/DefaultEntryLogger.java | 45 ++++++++++++-------
 .../InterleavedStorageRegenerateIndexOp.java  |  2 +-
 .../TransactionalEntryLogCompactor.java       |  2 +-
 .../bookie/storage/EntryLogScanner.java       |  2 +-
 .../directentrylogger/DirectEntryLogger.java  |  2 +-
 .../storage/ldb/LedgersIndexRebuildOp.java    |  2 +-
 .../storage/ldb/LocationsIndexRebuildOp.java  |  2 +-
 7 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index bb6b462ccbb..6a08f803c54 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -22,6 +22,7 @@
 package org.apache.bookkeeper.bookie;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.apache.bookkeeper.bookie.storage.EntryLogScanner.ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
@@ -1036,21 +1037,35 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                 }
                 // read the entry
                 data.clear();
-                int capacity = Math.min(scanner.getLengthToRead().getLengthToRead(), entrySize);
-                // skip read when scanner.getLengthToRead() == 0.
-                if (capacity > 0) {
-                    data.capacity(capacity);
-                    int rc = readFromLogChannel(entryLogId, bc, data, pos);
-                    if (rc != entrySize) {
-                        LOG.warn("Short read for ledger entry from entryLog {}@{} ({} != {})",
-                                entryLogId, pos, rc, entrySize);
-                        return;
-                    }
+                int rc;
+                // process the entry based on the read length type
+                switch (scanner.getReadLengthType()) {
+                    case READ_NOTHING:
+                        // skip read
+                        scanner.process(ledgerId, offset, entrySize);
+                        break;
+                    case READ_LEDGER_ENTRY_ID_LENGTH:
+                        data.capacity(READ_LEDGER_ENTRY_ID_LENGTH.getLengthToRead());
+                        rc = readFromLogChannel(entryLogId, bc, data, pos);
+                        if (rc != READ_LEDGER_ENTRY_ID_LENGTH.getLengthToRead()) {
+                            LOG.warn("Short read for ledger entry id from entrylog {}", entryLogId);
+                            return;
+                        }
+                        // drop the ledger id
+                        data.readLong();
+                        long entryId = data.readLong();
+                        scanner.process(ledgerId, offset, entrySize, entryId);
+                        break;
+                    case READ_ALL:
+                        data.capacity(entrySize);
+                        rc = readFromLogChannel(entryLogId, bc, data, pos);
+                        if (rc != entrySize) {
+                            LOG.warn("Short read for ledger entry id from entrylog {}", entryLogId);
+                            return;
+                        }
+                        scanner.process(ledgerId, offset, data, entrySize);
+                        break;
                 }
-
-                // process the entry
-                scanner.process(ledgerId, offset, data, entrySize);
-
                 // Advance position to the next entry
                 pos += entrySize;
             }
@@ -1180,7 +1195,7 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public ReadLengthType getLengthToRead(){
+            public ReadLengthType getReadLengthType(){
                 // we only need to read the entry size.
                 return ReadLengthType.READ_NOTHING;
             }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index c19a9075abe..4fac1a5c0ef 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -138,7 +138,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public ReadLengthType getLengthToRead() {
+                public ReadLengthType getReadLengthType() {
                     return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                 }
             });
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index 0a59a76caf5..01f7c7c9311 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -326,7 +326,7 @@ public void process(long ledgerId, long offset, int entrySize, long entryId) thr
                 }
 
                 @Override
-                public ReadLengthType getLengthToRead() {
+                public ReadLengthType getReadLengthType() {
                     return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                 }
             });
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index 2d8e738f1ec..e2bbf6ba97d 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -82,7 +82,7 @@ default void process(long ledgerId, long offset, int entrySize, long entryId) th
     default void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException{}
 
 
-    default ReadLengthType getLengthToRead(){
+    default ReadLengthType getReadLengthType(){
         return ReadLengthType.READ_ALL;
     }
 }
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
index 7758bcd9720..e0e71f72be7 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/DirectEntryLogger.java
@@ -434,7 +434,7 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public ReadLengthType getLengthToRead() {
+            public ReadLengthType getReadLengthType() {
                 return ReadLengthType.READ_NOTHING;
             }
         });
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
index d3636c0a78b..fcbd4770da5 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
@@ -176,7 +176,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public ReadLengthType getLengthToRead() {
+                public ReadLengthType getReadLengthType() {
                     return ReadLengthType.READ_NOTHING;
                 }
             });
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index 7b86213427b..5a67d4090a0 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -135,7 +135,7 @@ public boolean accept(long ledgerId) {
                     }
 
                     @Override
-                    public ReadLengthType getLengthToRead() {
+                    public ReadLengthType getReadLengthType() {
                         return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
                     }
                 });

From c6130b3abe218b100fecb16de6925de9b8d21e4e Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:07:50 +0800
Subject: [PATCH 07/13] fix.

---
 .../org/apache/bookkeeper/bookie/EntryLogCompactor.java   | 2 +-
 .../bookkeeper/bookie/TransactionalEntryLogCompactor.java | 2 +-
 .../apache/bookkeeper/bookie/storage/EntryLogScanner.java | 3 +--
 .../tools/cli/commands/bookie/ReadLogCommand.java         | 8 ++++----
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
index c669b8e77d0..81cd463761a 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogCompactor.java
@@ -91,7 +91,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(final long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
+                public void process(final long ledgerId, long offset, ByteBuf entry) throws IOException {
                     throttler.acquire(entry.readableBytes());
 
                     if (offsets.size() > maxOutstandingRequests) {
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index 01f7c7c9311..a221456bc0e 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -169,7 +169,7 @@ public boolean accept(long ledgerId) {
                 }
 
                 @Override
-                public void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException {
+                public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
                     throttler.acquire(entry.readableBytes());
                     synchronized (TransactionalEntryLogCompactor.this) {
                         long lid = entry.getLong(entry.readerIndex());
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index e2bbf6ba97d..d2708cc038e 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -77,9 +77,8 @@ default void process(long ledgerId, long offset, int entrySize, long entryId) th
      * @param ledgerId ledger id
      * @param offset offset of the entry
      * @param entry entry
-     * @param entrySize entry size
      */
-    default void process(long ledgerId, long offset, ByteBuf entry, int entrySize) throws IOException{}
+    default void process(long ledgerId, long offset, ByteBuf entry) throws IOException{}
 
 
     default ReadLengthType getReadLengthType(){
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
index d44e491f06c..3658ec49944 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
@@ -184,7 +184,7 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public void process(long ledgerId, long entryStartPos, ByteBuf entry, int entrySize) throws IOException {
+            public void process(long ledgerId, long entryStartPos, ByteBuf entry) throws IOException {
                 if (!stopScanning.booleanValue()) {
                     if ((rangeEndPos != -1) && (entryStartPos > rangeEndPos)) {
                         stopScanning.setValue(true);
@@ -197,7 +197,7 @@ public void process(long ledgerId, long entryStartPos, ByteBuf entry, int entryS
                          * 4 (intsize of entrySize). Please check
                          * EntryLogger.scanEntryLog.
                          */
-                        long entryEndPos = entryStartPos + entrySize + 4 - 1;
+                        long entryEndPos = entryStartPos + entry.readableBytes() + 4 - 1;
                         if (((rangeEndPos == -1) || (entryStartPos <= rangeEndPos)) && (rangeStartPos <= entryEndPos)) {
                             FormatUtil.formatEntry(entryStartPos, entry, printMsg, ledgerIdFormatter, entryFormatter);
                             entryFound.setValue(true);
@@ -255,7 +255,7 @@ public boolean accept(long candidateLedgerId) {
             }
 
             @Override
-            public void process(long candidateLedgerId, long startPos, ByteBuf entry, int entrySize) {
+            public void process(long candidateLedgerId, long startPos, ByteBuf entry) {
                 long entrysLedgerId = entry.getLong(entry.readerIndex());
                 long entrysEntryId = entry.getLong(entry.readerIndex() + 8);
                 if ((candidateLedgerId == entrysLedgerId) && (candidateLedgerId == ledgerId)
@@ -288,7 +288,7 @@ public boolean accept(long ledgerId) {
             }
 
             @Override
-            public void process(long ledgerId, long startPos, ByteBuf entry, int entrySize) {
+            public void process(long ledgerId, long startPos, ByteBuf entry) {
                 FormatUtil.formatEntry(startPos, entry, printMsg, ledgerIdFormatter, entryFormatter);
             }
         });

From 869b5ccea4289fc4605e9a75a8ab7a9747f3bf0f Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:14:29 +0800
Subject: [PATCH 08/13] fix.

---
 .../java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java   | 2 +-
 .../bookie/storage/directentrylogger/LogReaderScan.java         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index 6a08f803c54..6a9561b245f 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -1063,7 +1063,7 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                             LOG.warn("Short read for ledger entry id from entrylog {}", entryLogId);
                             return;
                         }
-                        scanner.process(ledgerId, offset, data, entrySize);
+                        scanner.process(ledgerId, offset, data);
                         break;
                 }
                 // Advance position to the next entry
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
index 7a032f64e0d..9718795143d 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
@@ -51,7 +51,7 @@ static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner s
                 reader.readIntoBufferAt(entry, offset, entrySize);
                 long ledgerId = entry.getLong(0);
                 if (ledgerId >= 0 && scanner.accept(ledgerId)) {
-                    scanner.process(ledgerId, initOffset, entry, entrySize);
+                    scanner.process(ledgerId, initOffset, entry);
                 }
                 offset += entrySize;
             }

From c2fd96ec1702acc0288f470646b1a792473f16fd Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:16:36 +0800
Subject: [PATCH 09/13] add code.

---
 .../bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java   | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
index 3658ec49944..edef6609ff2 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/tools/cli/commands/bookie/ReadLogCommand.java
@@ -189,6 +189,7 @@ public void process(long ledgerId, long entryStartPos, ByteBuf entry) throws IOE
                     if ((rangeEndPos != -1) && (entryStartPos > rangeEndPos)) {
                         stopScanning.setValue(true);
                     } else {
+                        int entrySize = entry.readableBytes();
                         /**
                          * entrySize of an entry (inclusive of payload and
                          * header) value is stored as int value in log file, but
@@ -197,7 +198,7 @@ public void process(long ledgerId, long entryStartPos, ByteBuf entry) throws IOE
                          * 4 (intsize of entrySize). Please check
                          * EntryLogger.scanEntryLog.
                          */
-                        long entryEndPos = entryStartPos + entry.readableBytes() + 4 - 1;
+                        long entryEndPos = entryStartPos + entrySize + 4 - 1;
                         if (((rangeEndPos == -1) || (entryStartPos <= rangeEndPos)) && (rangeStartPos <= entryEndPos)) {
                             FormatUtil.formatEntry(entryStartPos, entry, printMsg, ledgerIdFormatter, entryFormatter);
                             entryFound.setValue(true);

From 52dff17a5269df96bd3c983e5560c196bab898ee Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:36:31 +0800
Subject: [PATCH 10/13] add implementation in LogReaderScan.

---
 .../bookie/storage/EntryLogScanner.java       |  5 ++--
 .../directentrylogger/LogReaderScan.java      | 23 +++++++++++++++----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index d2708cc038e..efd3f4f7f8b 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -57,6 +57,7 @@ public int getLengthToRead() {
     /**
      * Process an entry when ReadLengthType is READ_NOTHING.
      * @param ledgerId ledger id
+     * @param offset init offset of the entry
      * @param entrySize entry size
      * @throws IOException
      */
@@ -65,7 +66,7 @@ default void process(long ledgerId, long offset, int entrySize) throws IOExcepti
     /**
      * Process an entry when ReadLengthType is READ_LEDGER_ENTRY_ID_LENGTH.
      * @param ledgerId ledger id
-     * @param offset offset of the entry
+     * @param offset init offset of the entry
      * @param entrySize entry size
      * @param entryId entry id
      * @throws IOException
@@ -75,7 +76,7 @@ default void process(long ledgerId, long offset, int entrySize, long entryId) th
     /**
      * Process an entry when ReadLengthType is READ_ALL.
      * @param ledgerId ledger id
-     * @param offset offset of the entry
+     * @param offset init offset of the entry
      * @param entry entry
      */
     default void process(long ledgerId, long offset, ByteBuf entry) throws IOException{}
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
index 9718795143d..323270865d4 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
@@ -26,6 +26,8 @@
 import java.io.IOException;
 import org.apache.bookkeeper.bookie.storage.EntryLogScanner;
 
+import static org.apache.bookkeeper.bookie.storage.directentrylogger.LogMetadata.INVALID_LID;
+
 class LogReaderScan {
     static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner scanner) throws IOException {
         int offset = Header.LOGFILE_LEGACY_HEADER_SIZE;
@@ -47,11 +49,24 @@ static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner s
                 // have realigned on the block boundary.
                 offset += Integer.BYTES;
 
+                long ledgerId = reader.readLongAt(offset);
+                if (ledgerId == INVALID_LID || !scanner.accept(ledgerId)) {
+                    offset += entrySize;
+                    continue;
+                }
+
                 entry.clear();
-                reader.readIntoBufferAt(entry, offset, entrySize);
-                long ledgerId = entry.getLong(0);
-                if (ledgerId >= 0 && scanner.accept(ledgerId)) {
-                    scanner.process(ledgerId, initOffset, entry);
+                switch (scanner.getReadLengthType()) {
+                    case READ_NOTHING:
+                        scanner.process(ledgerId, initOffset, entrySize);
+                        break;
+                    case READ_LEDGER_ENTRY_ID_LENGTH:
+                        long entryId = reader.readLongAt(offset + Long.BYTES);
+                        scanner.process(ledgerId, initOffset, entrySize, entryId);
+                        break;
+                    case READ_ALL:
+                        reader.readIntoBufferAt(entry, offset, entrySize);
+                        scanner.process(ledgerId, initOffset, entry);
                 }
                 offset += entrySize;
             }

From fdddd8b2e56e4660dccbe58ec772153116081614 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Thu, 21 Dec 2023 20:42:28 +0800
Subject: [PATCH 11/13] add code.

---
 .../apache/bookkeeper/bookie/DefaultEntryLogger.java | 12 +++++-------
 .../bookie/InterleavedStorageRegenerateIndexOp.java  |  2 +-
 .../bookie/TransactionalEntryLogCompactor.java       |  2 +-
 .../bookkeeper/bookie/storage/EntryLogScanner.java   |  4 ++--
 .../storage/directentrylogger/LogReaderScan.java     |  2 +-
 .../bookie/storage/ldb/LocationsIndexRebuildOp.java  |  4 ++--
 6 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index 6a9561b245f..b4255bb2c23 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -22,7 +22,7 @@
 package org.apache.bookkeeper.bookie;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static org.apache.bookkeeper.bookie.storage.EntryLogScanner.ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
+import static org.apache.bookkeeper.bookie.storage.EntryLogScanner.ReadLengthType.READ_LEDGER_ENTRY_ID;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
@@ -1044,16 +1044,14 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                         // skip read
                         scanner.process(ledgerId, offset, entrySize);
                         break;
-                    case READ_LEDGER_ENTRY_ID_LENGTH:
-                        data.capacity(READ_LEDGER_ENTRY_ID_LENGTH.getLengthToRead());
+                    case READ_LEDGER_ENTRY_ID:
+                        data.capacity(READ_LEDGER_ENTRY_ID.getLengthToRead());
                         rc = readFromLogChannel(entryLogId, bc, data, pos);
-                        if (rc != READ_LEDGER_ENTRY_ID_LENGTH.getLengthToRead()) {
+                        if (rc != READ_LEDGER_ENTRY_ID.getLengthToRead()) {
                             LOG.warn("Short read for ledger entry id from entrylog {}", entryLogId);
                             return;
                         }
-                        // drop the ledger id
-                        data.readLong();
-                        long entryId = data.readLong();
+                        long entryId = data.getLong(Long.BYTES);
                         scanner.process(ledgerId, offset, entrySize, entryId);
                         break;
                     case READ_ALL:
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
index 4fac1a5c0ef..0475819c48a 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/InterleavedStorageRegenerateIndexOp.java
@@ -139,7 +139,7 @@ public boolean accept(long ledgerId) {
 
                 @Override
                 public ReadLengthType getReadLengthType() {
-                    return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
+                    return ReadLengthType.READ_LEDGER_ENTRY_ID;
                 }
             });
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
index a221456bc0e..075052166bc 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/TransactionalEntryLogCompactor.java
@@ -327,7 +327,7 @@ public void process(long ledgerId, long offset, int entrySize, long entryId) thr
 
                 @Override
                 public ReadLengthType getReadLengthType() {
-                    return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
+                    return ReadLengthType.READ_LEDGER_ENTRY_ID;
                 }
             });
             LOG.info("Recovered {} entry locations from compacted log {}", offsets.size(), compactionLog.getDstLogId());
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index efd3f4f7f8b..934f3e5d56a 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -33,7 +33,7 @@ enum ReadLengthType {
         // Read nothing of the entry
         READ_NOTHING(0),
         // Read ledger id(8 byte) and entry id(8 byte) in the beginning of the entry
-        READ_LEDGER_ENTRY_ID_LENGTH(16);
+        READ_LEDGER_ENTRY_ID(16);
 
         private final int lengthToRead;
         ReadLengthType(int lengthToRead) {
@@ -77,7 +77,7 @@ default void process(long ledgerId, long offset, int entrySize, long entryId) th
      * Process an entry when ReadLengthType is READ_ALL.
      * @param ledgerId ledger id
      * @param offset init offset of the entry
-     * @param entry entry
+     * @param entry entry, containing ledgerId(8byte), entryId(8byte),... entrySize=entry.readableBytes()
      */
     default void process(long ledgerId, long offset, ByteBuf entry) throws IOException{}
 
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
index 323270865d4..32de6c5e1d2 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
@@ -60,7 +60,7 @@ static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner s
                     case READ_NOTHING:
                         scanner.process(ledgerId, initOffset, entrySize);
                         break;
-                    case READ_LEDGER_ENTRY_ID_LENGTH:
+                    case READ_LEDGER_ENTRY_ID:
                         long entryId = reader.readLongAt(offset + Long.BYTES);
                         scanner.process(ledgerId, initOffset, entrySize, entryId);
                         break;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
index 5a67d4090a0..af901fde95b 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LocationsIndexRebuildOp.java
@@ -21,7 +21,7 @@
 package org.apache.bookkeeper.bookie.storage.ldb;
 
 import com.google.common.collect.Sets;
-import io.netty.buffer.ByteBuf;
+
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.FileSystems;
@@ -136,7 +136,7 @@ public boolean accept(long ledgerId) {
 
                     @Override
                     public ReadLengthType getReadLengthType() {
-                        return ReadLengthType.READ_LEDGER_ENTRY_ID_LENGTH;
+                        return ReadLengthType.READ_LEDGER_ENTRY_ID;
                     }
                 });
 

From 04f076e49b33f0595498f981c08d731f62b2d5b7 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Sat, 23 Dec 2023 12:11:11 +0800
Subject: [PATCH 12/13] add default case.

---
 .../java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java  | 2 ++
 .../bookie/storage/directentrylogger/LogReaderScan.java        | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
index b4255bb2c23..a3a0da7ffe4 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/DefaultEntryLogger.java
@@ -1063,6 +1063,8 @@ public void scanEntryLog(long entryLogId, EntryLogScanner scanner) throws IOExce
                         }
                         scanner.process(ledgerId, offset, data);
                         break;
+                     default:
+                         throw new IOException("Unknown read length type " + scanner.getReadLengthType());
                 }
                 // Advance position to the next entry
                 pos += entrySize;
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
index 32de6c5e1d2..fa0aef25e09 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/directentrylogger/LogReaderScan.java
@@ -67,6 +67,9 @@ static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner s
                     case READ_ALL:
                         reader.readIntoBufferAt(entry, offset, entrySize);
                         scanner.process(ledgerId, initOffset, entry);
+                        break;
+                    default:
+                        throw new IOException("Unknown read length type: " + scanner.getReadLengthType());
                 }
                 offset += entrySize;
             }

From 4d2810e4d00a1eb9a5ce42a4c51fd7e12d9ebb23 Mon Sep 17 00:00:00 2001
From: thetumbled <843221020@qq.com>
Date: Sat, 23 Dec 2023 21:42:23 +0800
Subject: [PATCH 13/13] throw exception when not implemented right.

---
 .../bookie/storage/EntryLogScanner.java        | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
index 934f3e5d56a..091a3261913 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/EntryLogScanner.java
@@ -25,6 +25,12 @@
 
 /**
  * Scan entries in a entry log file.
+ * Implementation for this interface should choose one of the following ReadLengthType:
+ * READ_ALL, READ_NOTHING, READ_LEDGER_ENTRY_ID_LENGTH. <br/>
+ * If the implementation chooses READ_ALL, it should implement {@link #process(long, long, ByteBuf)}. <br/>
+ * If the implementation chooses READ_NOTHING, it should implement {@link #process(long, long, int)}. <br/>
+ * If the implementation chooses READ_LEDGER_ENTRY_ID_LENGTH, it should implement {@link #process(long, long, int, long)}. <br/>
+ *
  */
 public interface EntryLogScanner {
     enum ReadLengthType {
@@ -61,7 +67,9 @@ public int getLengthToRead() {
      * @param entrySize entry size
      * @throws IOException
      */
-    default void process(long ledgerId, long offset, int entrySize) throws IOException {}
+    default void process(long ledgerId, long offset, int entrySize) throws IOException {
+        throw new UnsupportedOperationException("Not implemented when ReadLengthType is READ_NOTHING");
+    }
 
     /**
      * Process an entry when ReadLengthType is READ_LEDGER_ENTRY_ID_LENGTH.
@@ -71,7 +79,9 @@ default void process(long ledgerId, long offset, int entrySize) throws IOExcepti
      * @param entryId entry id
      * @throws IOException
      */
-    default void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {}
+    default void process(long ledgerId, long offset, int entrySize, long entryId) throws IOException {
+        throw new UnsupportedOperationException("Not implemented when ReadLengthType is READ_LEDGER_ENTRY_ID_LENGTH");
+    }
 
     /**
      * Process an entry when ReadLengthType is READ_ALL.
@@ -79,7 +89,9 @@ default void process(long ledgerId, long offset, int entrySize, long entryId) th
      * @param offset init offset of the entry
      * @param entry entry, containing ledgerId(8byte), entryId(8byte),... entrySize=entry.readableBytes()
      */
-    default void process(long ledgerId, long offset, ByteBuf entry) throws IOException{}
+    default void process(long ledgerId, long offset, ByteBuf entry) throws IOException{
+        throw new UnsupportedOperationException("Not implemented when ReadLengthType is READ_ALL");
+    }
 
 
     default ReadLengthType getReadLengthType(){