From 8edc2f294cab738b336e5e708268eed778357c4d Mon Sep 17 00:00:00 2001
From: Gavin Chou <gavin@selectdb.com>
Date: Sun, 14 Dec 2025 15:31:35 +0800
Subject: [PATCH 1/2] [Fix](recycler) Fix possible null pointer when first
 txn->get() failed

---
 cloud/src/recycler/recycler.cpp | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/cloud/src/recycler/recycler.cpp b/cloud/src/recycler/recycler.cpp
index 7527b3b3b0879d..13fc11644a78e0 100644
--- a/cloud/src/recycler/recycler.cpp
+++ b/cloud/src/recycler/recycler.cpp
@@ -2967,11 +2967,11 @@ int InstanceRecycler::scan_and_recycle(
     };
 
     std::unique_ptr<RangeGetIterator> it;
-    do {
+    while (it == nullptr /* may be not init */ || (it->more() && !stopped())) {
         if (get_range_retried > 1000) {
-            err = "txn_get exceeds max retry, may not scan all keys";
-            ret = -1;
-            return -1;
+            err = "txn_get exceeds max retry(1000), may not scan all keys";
+            ret = -2;
+            return ret;
         }
         int get_ret = txn_get(txn_kv_.get(), begin, end, it);
         if (get_ret != 0) { // txn kv may complain "Request for future version"
@@ -2995,18 +2995,24 @@ int InstanceRecycler::scan_and_recycle(
                 VLOG_DEBUG << "iterator has no more kvs. key=" << hex(k);
             }
             // if we want to continue scanning, the recycle_func should not return non-zero
-            if (recycle_func(k, v) != 0) {
-                err = "recycle_func error";
+            int recycle_func_ret = recycle_func(k, v);
+            if (recycle_func_ret != 0) {
+                err = "recycle_func error, ret=" + std::to_string(recycle_func_ret);
                 ret = -1;
+                return ret;
             }
         }
         begin.push_back('\x00'); // Update to next smallest key for iteration
-        // if we want to continue scanning, the recycle_func should not return non-zero
-        if (loop_done && loop_done() != 0) {
-            err = "loop_done error";
-            ret = -1;
+        // if we want to continue scanning, the loop_done should not return non-zero
+        if (loop_done) {
+            int loop_done_ret = loop_done();
+            if (loop_done_ret != 0) {
+                err = "loop_done error, ret=" + std::to_string(loop_done_ret);
+                ret = -1;
+                return ret;
+            }
         }
-    } while (it->more() && !stopped());
+    }
     return ret;
 }
 

From ed9e8149daa970b2e1961d1853aca48eca1b116e Mon Sep 17 00:00:00 2001
From: Gavin Chou <gavin@selectdb.com>
Date: Sun, 14 Dec 2025 20:48:59 +0800
Subject: [PATCH 2/2] Fix UT

---
 cloud/src/recycler/recycler.cpp | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/cloud/src/recycler/recycler.cpp b/cloud/src/recycler/recycler.cpp
index 13fc11644a78e0..4a7b7b499135ff 100644
--- a/cloud/src/recycler/recycler.cpp
+++ b/cloud/src/recycler/recycler.cpp
@@ -2969,9 +2969,9 @@ int InstanceRecycler::scan_and_recycle(
     std::unique_ptr<RangeGetIterator> it;
     while (it == nullptr /* may be not init */ || (it->more() && !stopped())) {
         if (get_range_retried > 1000) {
-            err = "txn_get exceeds max retry(1000), may not scan all keys";
-            ret = -2;
-            return ret;
+            err = "txn_get exceeds max retry, may not scan all keys";
+            ret = -1;
+            return -1;
         }
         int get_ret = txn_get(txn_kv_.get(), begin, end, it);
         if (get_ret != 0) { // txn kv may complain "Request for future version"
@@ -2995,22 +2995,16 @@ int InstanceRecycler::scan_and_recycle(
                 VLOG_DEBUG << "iterator has no more kvs. key=" << hex(k);
             }
             // if we want to continue scanning, the recycle_func should not return non-zero
-            int recycle_func_ret = recycle_func(k, v);
-            if (recycle_func_ret != 0) {
-                err = "recycle_func error, ret=" + std::to_string(recycle_func_ret);
+            if (recycle_func(k, v) != 0) {
+                err = "recycle_func error";
                 ret = -1;
-                return ret;
             }
         }
         begin.push_back('\x00'); // Update to next smallest key for iteration
-        // if we want to continue scanning, the loop_done should not return non-zero
-        if (loop_done) {
-            int loop_done_ret = loop_done();
-            if (loop_done_ret != 0) {
-                err = "loop_done error, ret=" + std::to_string(loop_done_ret);
-                ret = -1;
-                return ret;
-            }
+        // if we want to continue scanning, the recycle_func should not return non-zero
+        if (loop_done && loop_done() != 0) {
+            err = "loop_done error";
+            ret = -1;
         }
     }
     return ret;