diff --git a/src/brpc/ubshm/common/common.h b/src/brpc/ubshm/common/common.h
index f5bffa14b9..c64ae9843f 100644
--- a/src/brpc/ubshm/common/common.h
+++ b/src/brpc/ubshm/common/common.h
@@ -130,9 +130,9 @@ static inline uint64_t GetCurNanoSeconds(void) {
 
 #define FREE_PTR(ptr) \
     do {              \
-        if ((ptr) != NULL) { \
+        if ((ptr) != nullptr) { \
             free(ptr);    \
-            (ptr) = NULL; \
+            (ptr) = nullptr; \
         }             \
     } while (0)
 
diff --git a/src/brpc/ubshm/common/thread_lock.h b/src/brpc/ubshm/common/thread_lock.h
index 3c274ce0cd..0233955168 100644
--- a/src/brpc/ubshm/common/thread_lock.h
+++ b/src/brpc/ubshm/common/thread_lock.h
@@ -30,7 +30,7 @@ extern "C" {
 
 static inline void UnlockMutex(pthread_mutex_t **mtx)
 {
-    if (LIKELY(mtx != NULL && *mtx != NULL)) {
+    if (LIKELY(mtx != nullptr && *mtx != nullptr)) {
         pthread_mutex_unlock(*mtx);
     } else {
         LOG(ERROR) << "Invalid input for mtx.";
diff --git a/src/brpc/ubshm/shm/shm_ipc.cpp b/src/brpc/ubshm/shm/shm_ipc.cpp
index a63e9cdd7c..f0a9d7ea1c 100644
--- a/src/brpc/ubshm/shm/shm_ipc.cpp
+++ b/src/brpc/ubshm/shm/shm_ipc.cpp
@@ -91,10 +91,10 @@ RETURN_CODE IpcShmLocalMalloc(SHM *shm)
         return SHM_ERR;
     }
 
-    shm->addr = (uint8_t*)mmap(NULL, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    shm->addr = (uint8_t*)mmap(nullptr, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
     if (shm->addr == (uint8_t*)MAP_FAILED) {
         LOG(ERROR) << "IPC map shm=" << shm->name << " length=" << shm->len << " failed, ret(" << errno << ").";
-        shm->addr = NULL;
+        shm->addr = nullptr;
         close(fd);
         shm_unlink(shm->name);
         return SHM_ERR;
@@ -106,7 +106,7 @@ RETURN_CODE IpcShmLocalMalloc(SHM *shm)
 
 RETURN_CODE IpcShmMunmap(SHM *shm)
 {
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(INFO) << "IPC unmap shm=" << shm->name << " already unmapped.";
         return UBRING_OK;
     }
@@ -117,7 +117,7 @@ RETURN_CODE IpcShmMunmap(SHM *shm)
         return SHM_ERR;
     }
 
-    shm->addr = NULL;
+    shm->addr = nullptr;
     LOG(INFO) << "IPC unmap shm=" << shm->name << " length=" << shm->len << " success.";
     return UBRING_OK;
 }
@@ -133,7 +133,7 @@ RETURN_CODE IpcShmFree(SHM *shm)
         }
         if (errno == ENOENT) {
             LOG(INFO) << "IPC free shm=" << shm->name << " already deleted.";
-            shm->addr = NULL;
+            shm->addr = nullptr;
             return SHM_ERR_NOT_FOUND;
         }
         LOG_EVERY_SECOND(ERROR) << "IPC free shm=" << shm->name << " failed, errno=" << errno;
@@ -144,7 +144,7 @@ RETURN_CODE IpcShmFree(SHM *shm)
 
 RETURN_CODE IpcShmLocalFree(SHM *shm)
 {
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(INFO) << "IPC free local shm=" << shm->name << " already freed.";
         return SHM_ERR_NOT_FOUND;
     }
@@ -153,7 +153,7 @@ RETURN_CODE IpcShmLocalFree(SHM *shm)
     if (ret != UBRING_OK) {
         LOG(WARNING) << "IPC unmap shm=" << shm->name << " failed, ret=" << ret;
     } else {
-        shm->addr = NULL;
+        shm->addr = nullptr;
     }
 
     ret = shm_unlink(shm->name);
@@ -164,13 +164,13 @@ RETURN_CODE IpcShmLocalFree(SHM *shm)
         }
         if (errno == ENOENT) {
             LOG(INFO) << "IPC delete shm=" << shm->name << " already deleted by peer.";
-            shm->addr = NULL;
+            shm->addr = nullptr;
             return SHM_ERR_NOT_FOUND;
         }
         LOG_EVERY_SECOND(ERROR) << "IPC delete shm=" << shm->name << " failed, ret=" << ret;
         return SHM_ERR;
     }
-    shm->addr = NULL;
+    shm->addr = nullptr;
     LOG(INFO) << "IPC free local shm=" << shm->name << " success.";
     return UBRING_OK;
 }
@@ -188,10 +188,10 @@ RETURN_CODE IpcShmRemoteMalloc(SHM *shm)
         return SHM_ERR;
     }
 
-    shm->addr = (uint8_t*)mmap(NULL, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    shm->addr = (uint8_t*)mmap(nullptr, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
     if (shm->addr == (uint8_t*)MAP_FAILED) {
         LOG(ERROR) << "IPC map shm=" << shm->name << " failed, ret=" << errno;
-        shm->addr = NULL;
+        shm->addr = nullptr;
         close(fd);
         return SHM_ERR;
     }
@@ -213,10 +213,10 @@ RETURN_CODE IpcShmLocalMmap(SHM *shm, int prot)
         return SHM_ERR;
     }
 
-    shm->addr = (uint8_t*)mmap(NULL, shm->len, prot, MAP_SHARED, fd, 0);
+    shm->addr = (uint8_t*)mmap(nullptr, shm->len, prot, MAP_SHARED, fd, 0);
     if (shm->addr == (uint8_t*)MAP_FAILED) {
         LOG(ERROR) << "IPC map shm=" << shm->name << " failed, ret=" << errno;
-        shm->addr = NULL;
+        shm->addr = nullptr;
         close(fd);
         return SHM_ERR;
     }
@@ -228,7 +228,7 @@ RETURN_CODE IpcShmLocalMmap(SHM *shm, int prot)
 
 RETURN_CODE IpcShmRemoteFree(SHM *shm)
 {
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(INFO) << "IPC free remote shm=" << shm->name << " already freed.";
         return UBRING_OK;
     }
@@ -239,7 +239,7 @@ RETURN_CODE IpcShmRemoteFree(SHM *shm)
         return SHM_ERR;
     }
 
-    shm->addr = NULL;
+    shm->addr = nullptr;
     LOG(INFO) << "IPC free remote shm=" << shm->name << " success.";
     return UBRING_OK;
 }
diff --git a/src/brpc/ubshm/shm/shm_mgr.cpp b/src/brpc/ubshm/shm/shm_mgr.cpp
index 9535cc1a90..ea01113e54 100644
--- a/src/brpc/ubshm/shm/shm_mgr.cpp
+++ b/src/brpc/ubshm/shm/shm_mgr.cpp
@@ -31,7 +31,7 @@ DEFINE_int32(ub_shm_type, 1, "shm type: 1-ipc; 2-ub_ring");
 static SHM_TYPE g_shm_type;
 
 static bool CheckInputShmParam(SHM *shm) {
-    if (shm == NULL) {
+    if (shm == nullptr) {
         LOG(ERROR) << "Input Param shm is NULL.";
         return false;
     }
@@ -114,7 +114,7 @@ RETURN_CODE ShmLocalCalloc(SHM *shm) {
         LOG(ERROR) << "Failed to alloc local shm.";
         return rc;
     }
-    if (UNLIKELY(shm->addr == NULL)) {
+    if (UNLIKELY(shm->addr == nullptr)) {
         LOG(ERROR) << "Local shm=" << shm->name << " allocated with NULL address.";
         ShmFree(shm);
         return SHM_ERR;
diff --git a/src/brpc/ubshm/shm/shm_ubs.cpp b/src/brpc/ubshm/shm/shm_ubs.cpp
index f1da0fc7a7..2d06b0a15b 100644
--- a/src/brpc/ubshm/shm/shm_ubs.cpp
+++ b/src/brpc/ubshm/shm/shm_ubs.cpp
@@ -36,7 +36,7 @@
 
 namespace brpc {
 namespace ubring {
-#define UBRING_MK_UBSM(ret, fn, args) ret (*fn) args = NULL
+#define UBRING_MK_UBSM(ret, fn, args) ret (*fn) args = nullptr
 #include "brpc/ubshm/ubs_mem/declare_shm_ubs.h"
 #define SHM_RIGHT_MODE 0666
 #define UBRING_REGION_NAME_PREFIX "UbrONE2ALLRegion"
@@ -47,7 +47,7 @@ DEFINE_int32(ub_flying_io_timeout, 5, "Waiting time for stopping data"
             "sending and receiving when the link is disconnected.");
 char g_region_name[MAX_REGION_NAME_DESC_LENGTH] = {0};
 int g_shm_timer_fd = 0;
-ShmList *g_shm_list = NULL;
+ShmList *g_shm_list = nullptr;
 static RETURN_CODE UbsShmInterfacesLoad(void);
 char hostname[MAX_HOST_NAME_DESC_LENGTH];
 
@@ -60,7 +60,7 @@ RETURN_CODE UbsShmInterfacesLoad(void)
 #elif defined(OS_MACOSX)
     void* dlhandler = dlopen(ubsm_sdk_location, RTLD_NOW | RTLD_LOCAL | RTLD_NODELETE);
 #endif
-    if (dlhandler == NULL) {
+    if (dlhandler == nullptr) {
         LOG(ERROR) << "Dlopen libubsm_sdk.so in " << ubsm_sdk_location << " failed, error:" << dlerror();
         return UBRING_ERR;
     }
@@ -72,11 +72,11 @@ RETURN_CODE UbsShmInterfacesLoad(void)
 
 #define UBRING_MK_UBSM(ret, fn, args)                                                   \
     do {                                                                             \
-        if ((fn) != NULL) {                                                          \
+        if ((fn) != nullptr) {                                                          \
             break;                                                                   \
         }                                                                            \
         UBRING_MK_UBSM_OPTIONAL(ret, fn, args);                                         \
-        if ((fn) == NULL) {                                                          \
+        if ((fn) == nullptr) {                                                          \
             LOG(ERROR) << "Fail load ubs_mem func " << #fn <<" error:" << dlerror(); \
             return UBRING_ERR;                                                          \
         }                                                                            \
@@ -84,7 +84,7 @@ RETURN_CODE UbsShmInterfacesLoad(void)
 #include "brpc/ubshm/ubs_mem/declare_shm_ubs.h"
 
     dlclose(dlhandler);
-    dlhandler = NULL;
+    dlhandler = nullptr;
 #endif
     return UBRING_OK;
 }
@@ -155,7 +155,7 @@ do {
     }
 } while (0);
 
-    ret = ubsmem_shmem_map(NULL, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
+    ret = ubsmem_shmem_map(nullptr, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
     if (ret != UBSM_OK) {
         LOG(ERROR) << "Ubs map shm=" << shm->name << " failed, ret=" << ret;
         if (ret == UBSM_ERR_NOT_FOUND) {
@@ -174,7 +174,7 @@ do {
 RETURN_CODE UbsShmMunmap(SHM *shm)
 {
     // unmap
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(ERROR) << "Ubs input shm param is invalid, addr is NULL.";
         return SHM_ERR_INPUT_INVALID;
     }
@@ -196,7 +196,7 @@ RETURN_CODE UbsShmMunmap(SHM *shm)
 
 RETURN_CODE UbsShmFree(SHM *shm)
 {
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(ERROR) << "Ubs input shm param is invalid, addr is NULL.";
         return SHM_ERR_INPUT_INVALID;
     }
@@ -214,7 +214,7 @@ RETURN_CODE UbsShmFree(SHM *shm)
         LOG(ERROR) << "Ubs free shm="<< shm->name << " failed, ret=" << ret;
         return SHM_ERR;
     }
-    shm->addr = NULL;
+    shm->addr = nullptr;
     LOG(INFO) << "Ubs free shm=" << shm->name << " length=" << shm->len << " success.";
     return UBRING_OK;
 }
@@ -222,7 +222,7 @@ RETURN_CODE UbsShmFree(SHM *shm)
 RETURN_CODE UbsShmLocalFree(SHM *shm)
 {
     // unmap
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(ERROR) << "Ubs input shm param is invalid, addr is NULL.";
         return SHM_ERR_INPUT_INVALID;
     }
@@ -247,14 +247,14 @@ RETURN_CODE UbsShmLocalFree(SHM *shm)
         LOG(ERROR) << "Ubs delete shm=" << shm->name << " failed, ret=" << ret;
         return SHM_ERR;
     }
-    shm->addr = NULL;
+    shm->addr = nullptr;
     LOG(INFO) << "Ubs free local shm=" << shm->name << " length=" << shm->len << " success.";
     return UBRING_OK;
 }
 
 RETURN_CODE UbsShmRemoteMalloc(SHM *shm)
 {
-    int ret = ubsmem_shmem_map(NULL, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
+    int ret = ubsmem_shmem_map(nullptr, shm->len, PROT_READ | PROT_WRITE, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
     if (ret != UBSM_OK) {
         LOG(ERROR) << "Ubs map Shm=" << shm->name << " failed, ret=" << ret;
         return SHM_ERR;
@@ -266,7 +266,7 @@ RETURN_CODE UbsShmRemoteMalloc(SHM *shm)
 
 RETURN_CODE UbsShmLocalMmap(SHM *shm, int prot)
 {
-    int ret = ubsmem_shmem_map(NULL, shm->len, prot, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
+    int ret = ubsmem_shmem_map(nullptr, shm->len, prot, MAP_SHARED, shm->name, 0, (void**)&(shm->addr));
     if (ret != UBSM_OK) {
         LOG(ERROR) << "Ubs map Shm=" << shm->name << " failed, ret=" << ret;
         return SHM_ERR;
@@ -279,7 +279,7 @@ RETURN_CODE UbsShmLocalMmap(SHM *shm, int prot)
 RETURN_CODE UbsShmRemoteFree(SHM *shm)
 {
     // unmap
-    if (shm->addr == NULL) {
+    if (shm->addr == nullptr) {
         LOG(ERROR) << "Ubs input shm param is invalid, addr is NULL.";
         return SHM_ERR_INPUT_INVALID;
     }
@@ -393,16 +393,16 @@ RETURN_CODE UbsShmFini(void)
 
 static void DeleteShmToList(ShmList* shm_list)
 {
-    if (shm_list == NULL || shm_list->head == NULL) {
+    if (shm_list == nullptr || shm_list->head == nullptr) {
         return;
     }
 
     ShmListNode *cur_node = shm_list->head;
     shm_list->head = cur_node->next;
-    if (shm_list->head != NULL) {
-        shm_list->head->prev = NULL;
+    if (shm_list->head != nullptr) {
+        shm_list->head->prev = nullptr;
     } else {
-        shm_list->tail = NULL;
+        shm_list->tail = nullptr;
     }
     LOG(INFO) << "Delete shm to list, name=" << cur_node->shm.name << " size=" << shm_list->size;
     FREE_PTR(cur_node);
@@ -412,26 +412,26 @@ static void DeleteShmToList(ShmList* shm_list)
 void *UbsShmCallback(void* args)
 {
     ShmList *shm_list = (ShmList*)args;
-    if (UNLIKELY(shm_list == NULL)) {
+    if (UNLIKELY(shm_list == nullptr)) {
         LOG(ERROR) << "Shm list is null.";
-        return NULL;
+        return nullptr;
     }
 
     LOCK_GUARD(shm_list->shm_lock);
-    while (shm_list->head != NULL) {
+    while (shm_list->head != nullptr) {
         SHM shm = shm_list->head->shm;
-        if (shm.addr == NULL) {
+        if (shm.addr == nullptr) {
             LOG(ERROR) << "Ubs input shm param is invalid, addr is NULL.";
-            return NULL;
+            return nullptr;
         }
 
         int ret = ubsmem_shmem_unmap(shm.addr, shm.len);
         if (ret != UBSM_OK) {
             if (ret == UBSM_ERR_NET) {
-                return NULL;
+                return nullptr;
             }
             LOG(ERROR) << "Ubs unmap shm=" << shm.name << " length=" << shm.len << " failed, ret=" << ret;
-            return NULL;
+            return nullptr;
         }
         LOG(INFO) << "Ubs unmap shm=" << shm.name << " length=" << shm.len << " success.";
 
@@ -439,13 +439,13 @@ void *UbsShmCallback(void* args)
         if (ret != UBSM_OK) {
             DeleteShmToList(shm_list);
             LOG(ERROR) << "Ubs delete shm=" << shm.name << " failed, ret=" << ret;
-            return NULL;
+            return nullptr;
         }
         DeleteShmToList(shm_list);
         LOG(INFO) << "Ubs free local shm=" << shm.name << " length=" << shm.len << " success.";
     }
 
-    return NULL;
+    return nullptr;
 }
 
 RETURN_CODE UbsShmAddTimer(ShmList *shm_list)
@@ -468,15 +468,15 @@ RETURN_CODE UbsShmAddTimer(ShmList *shm_list)
 RETURN_CODE InitShmTimer(ShmList **shm_list)
 {
     *shm_list = (ShmList *)malloc(sizeof(ShmList));
-    if (*shm_list == NULL) {
+    if (*shm_list == nullptr) {
         LOG(ERROR) << "Malloc shm list failed.";
         return UBRING_ERR;
     }
-    (*shm_list)->head = NULL;
-    (*shm_list)->tail = NULL;
+    (*shm_list)->head = nullptr;
+    (*shm_list)->tail = nullptr;
     (*shm_list)->size = 0;
 
-    if (pthread_mutex_init(&(*shm_list)->shm_lock, NULL) != 0) {
+    if (pthread_mutex_init(&(*shm_list)->shm_lock, nullptr) != 0) {
         LOG(ERROR) << "Init shm list mutex failed.";
         FREE_PTR(*shm_list);
         return UBRING_ERR;
@@ -493,14 +493,14 @@ RETURN_CODE InitShmTimer(ShmList **shm_list)
 RETURN_CODE DestroyShmTimer(ShmList *shm_list)
 {
     DeleteTimerSafe((uint32_t)g_shm_timer_fd);
-    if (shm_list == NULL) {
+    if (shm_list == nullptr) {
         LOG(WARNING) << "Shm list is null.";
         return UBRING_ERR;
     }
     ShmListNode* current = shm_list->head;
     ShmListNode* next;
 
-    while (current != NULL) {
+    while (current != nullptr) {
         next = current->next;
         free(current);
         current = next;
@@ -512,14 +512,14 @@ RETURN_CODE DestroyShmTimer(ShmList *shm_list)
 
 RETURN_CODE IsExistInShmList(ShmList *shm_list, const SHM *shm)
 {
-     if (UNLIKELY(shm_list == NULL || shm == NULL)) {
+     if (UNLIKELY(shm_list == nullptr || shm == nullptr)) {
          LOG(ERROR) << "Shm list or shm is null.";
          return UBRING_ERR;
      }
      LOCK_GUARD(shm_list->shm_lock);
 
     ShmListNode *cur_node = shm_list->head;
-    while (cur_node != NULL) {
+    while (cur_node != nullptr) {
         if (strcmp(cur_node->shm.name, shm->name) == 0 && cur_node->shm.len == shm->len) {
             return UBRING_OK;
         }
@@ -530,7 +530,7 @@ RETURN_CODE IsExistInShmList(ShmList *shm_list, const SHM *shm)
 
 RETURN_CODE AddShmToList(ShmList *shm_list, SHM *shm)
 {
-    if (shm_list == NULL || shm == NULL) {
+    if (shm_list == nullptr || shm == nullptr) {
         LOG(ERROR) << "Shm list or shm is null.";
         return UBRING_ERR;
     }
@@ -541,14 +541,14 @@ RETURN_CODE AddShmToList(ShmList *shm_list, SHM *shm)
     }
 
     ShmListNode *new_shm_node = (ShmListNode *)malloc(sizeof(ShmListNode));
-    if (new_shm_node == NULL) {
+    if (new_shm_node == nullptr) {
         LOG(ERROR) << "Malloc shm node failed.";
         return UBRING_ERR;
     }
 
     memcpy(&new_shm_node->shm, shm, sizeof(SHM));
     LOCK_GUARD(shm_list->shm_lock);
-    new_shm_node->next = NULL;
+    new_shm_node->next = nullptr;
     new_shm_node->prev = shm_list->tail;
     if (shm_list->tail) {
         shm_list->tail->next = new_shm_node;
diff --git a/src/brpc/ubshm/timer/timer_mgr.cpp b/src/brpc/ubshm/timer/timer_mgr.cpp
index b563e7f6ab..b5e0c9ef3b 100644
--- a/src/brpc/ubshm/timer/timer_mgr.cpp
+++ b/src/brpc/ubshm/timer/timer_mgr.cpp
@@ -31,7 +31,7 @@ namespace ubring {
 
 int32_t g_epoll_fd = -1;
 std::atomic<uint32_t> g_total_timer_num(0);
-TimerFdCtx *g_timer_fd_ctx_map = NULL;
+TimerFdCtx *g_timer_fd_ctx_map = nullptr;
 uint32_t g_max_system_fd = 0;
 static pthread_t g_epoll_execute_thread = 0;
 static int32_t g_timer_module_initialized = 0;
@@ -44,7 +44,7 @@ static int timerfd_settime_macosx(int fd, int flags,
 #endif
 
 static RETURN_CODE DeleteTimerInner(uint32_t fd) {
-    if (g_timer_fd_ctx_map == NULL) {
+    if (g_timer_fd_ctx_map == nullptr) {
         return UBRING_OK;
     }
 
@@ -58,19 +58,19 @@ static RETURN_CODE DeleteTimerInner(uint32_t fd) {
     }
 
     g_timer_fd_ctx_map[fd].status = TIMER_CONTEXT_NOT_USING;
-    g_timer_fd_ctx_map[fd].cb = NULL;
-    g_timer_fd_ctx_map[fd].args = NULL;
+    g_timer_fd_ctx_map[fd].cb = nullptr;
+    g_timer_fd_ctx_map[fd].args = nullptr;
     g_timer_fd_ctx_map[fd].periodical = 0;
     g_timer_fd_ctx_map[fd].fd = 0;
 
     pthread_spin_unlock(&g_timer_fd_ctx_map[fd].spin_lock);
 
 #if defined(OS_LINUX)
-    epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, (int)fd, NULL);
+    epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, (int)fd, nullptr);
 #elif defined(OS_MACOSX)
     struct kevent evt;
-    EV_SET(&evt, fd, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
-    kevent(g_epoll_fd, &evt, 1, NULL, 0, NULL);
+    EV_SET(&evt, fd, EVFILT_TIMER, EV_DELETE, 0, 0, nullptr);
+    kevent(g_epoll_fd, &evt, 1, nullptr, 0, nullptr);
 #endif
 
     uint64_t exp = 0;
@@ -92,7 +92,7 @@ static RETURN_CODE StartTimeEpoll(void) {
         return UBRING_ERR;
     }
 
-    int ret = pthread_create(&g_epoll_execute_thread, NULL, TimerEpoll, NULL);
+    int ret = pthread_create(&g_epoll_execute_thread, nullptr, TimerEpoll, nullptr);
     if (UNLIKELY(ret != 0)) {
         LOG(ERROR) << "Failed to create thread err=" << ret;
         return UBRING_ERR;
@@ -101,7 +101,7 @@ static RETURN_CODE StartTimeEpoll(void) {
 }
 
 static RETURN_CODE TimerSpinLocksInit(void) {
-    if (g_timer_fd_ctx_map == NULL) {
+    if (g_timer_fd_ctx_map == nullptr) {
         LOG(ERROR) << "Timer module is not fully initialized.";
         return UBRING_ERR;
     }
@@ -150,7 +150,7 @@ RETURN_CODE TimerInit(void) {
     }
     g_max_system_fd = (uint32_t)rlim.rlim_cur;
 
-    if (g_timer_fd_ctx_map == NULL) {
+    if (g_timer_fd_ctx_map == nullptr) {
         g_timer_fd_ctx_map = (TimerFdCtx *)malloc(sizeof(TimerFdCtx) * g_max_system_fd);
         if (UNLIKELY(!g_timer_fd_ctx_map)) {
             LOG(ERROR) << "Fail to malloc space for timer modules. errno=%d", errno;
@@ -161,7 +161,7 @@ RETURN_CODE TimerInit(void) {
         if (ret != UBRING_OK) {
             LOG(ERROR) << "Failed to init main data structure of Time Module. ret=" << ret;
             free(g_timer_fd_ctx_map);
-            g_timer_fd_ctx_map = NULL;
+            g_timer_fd_ctx_map = nullptr;
             return UBRING_ERR;
         }
     }
@@ -169,7 +169,7 @@ RETURN_CODE TimerInit(void) {
     RETURN_CODE ret = StartTimeEpoll();
     if (ret != UBRING_OK) {
         LOG(ERROR) << "Failed to start Timer Epoll. ret=" << ret;
-        if (LIKELY(g_timer_fd_ctx_map != NULL)) {
+        if (LIKELY(g_timer_fd_ctx_map != nullptr)) {
             FREE_PTR(g_timer_fd_ctx_map);
         }
         return UBRING_ERR;
@@ -181,12 +181,12 @@ RETURN_CODE TimerInit(void) {
 void *UnifiedCallback(void *args) {
     TimerFdCtx *ctx = (TimerFdCtx *)args;
     if (pthread_spin_lock(&ctx->spin_lock) != 0) {
-        return NULL;
+        return nullptr;
     }
 
     if (ctx->status == TIMER_CONTEXT_NOT_USING) {
         pthread_spin_unlock(&ctx->spin_lock);
-        return NULL;
+        return nullptr;
     }
 
     void *(*cb)(void *) = ctx->cb;
@@ -202,7 +202,7 @@ void *UnifiedCallback(void *args) {
     if (!is_periodical) {
         DeleteTimerInner(fd);
     }
-    return NULL;
+    return nullptr;
 }
 
 void *TimerEpoll(void *args) {
@@ -224,7 +224,7 @@ void *TimerEpoll(void *args) {
                                       TIMER_EPOLL_WAIT_TIMEOUT);
 #elif defined(OS_MACOSX)
         struct timespec timeout = {0, TIMER_EPOLL_WAIT_TIMEOUT * 1000000};
-        int32_t ready_num = kevent(g_epoll_fd, NULL, 0, ready_events, MAX_TIMER, &timeout);
+        int32_t ready_num = kevent(g_epoll_fd, nullptr, 0, ready_events, MAX_TIMER, &timeout);
 #endif
 
         if (UNLIKELY(ready_num == -1)) {
@@ -268,11 +268,11 @@ void *TimerEpoll(void *args) {
             }
         }
     }
-    return NULL;
+    return nullptr;
 }
 
 void DeleteTimerSafe(uint32_t fd) {
-    if (g_timer_fd_ctx_map == NULL) {
+    if (g_timer_fd_ctx_map == nullptr) {
         return;
     }
 
@@ -286,19 +286,19 @@ void DeleteTimerSafe(uint32_t fd) {
     }
 
     g_timer_fd_ctx_map[fd].status = TIMER_CONTEXT_NOT_USING;
-    g_timer_fd_ctx_map[fd].cb = NULL;
-    g_timer_fd_ctx_map[fd].args = NULL;
+    g_timer_fd_ctx_map[fd].cb = nullptr;
+    g_timer_fd_ctx_map[fd].args = nullptr;
     g_timer_fd_ctx_map[fd].periodical = 0;
     g_timer_fd_ctx_map[fd].fd = 0;
 
     pthread_spin_unlock(&g_timer_fd_ctx_map[fd].spin_lock);
 
 #if defined(OS_LINUX)
-    epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, (int)fd, NULL);
+    epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, (int)fd, nullptr);
 #elif defined(OS_MACOSX)
     struct kevent evt;
-    EV_SET(&evt, fd, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
-    kevent(g_epoll_fd, &evt, 1, NULL, 0, NULL);
+    EV_SET(&evt, fd, EVFILT_TIMER, EV_DELETE, 0, 0, nullptr);
+    kevent(g_epoll_fd, &evt, 1, nullptr, 0, nullptr);
 #endif
 
     uint64_t exp = 0;
@@ -309,7 +309,7 @@ void DeleteTimerSafe(uint32_t fd) {
 }
 
 void DeleteTimer(uint32_t fd) {
-    if (g_timer_fd_ctx_map == NULL) {
+    if (g_timer_fd_ctx_map == nullptr) {
         LOG(WARNING) << "The timer is not initialized.";
         return;
     }
@@ -355,8 +355,8 @@ int32_t TimerStart(const itimerspec *time, void *(*cb)(void *), void *args) {
     uint64_t timeout_nsec = time->it_value.tv_sec * 1000000000ULL + time->it_value.tv_nsec;
     uint64_t interval_nsec = time->it_interval.tv_sec * 1000000000ULL + time->it_interval.tv_nsec;
     EV_SET(&event, timer_fd, EVFILT_TIMER, EV_ADD | EV_ENABLE, 0,
-           timeout_nsec / 1000000, NULL);
-    int32_t ret = kevent(g_epoll_fd, &event, 1, NULL, 0, NULL);
+           timeout_nsec / 1000000, nullptr);
+    int32_t ret = kevent(g_epoll_fd, &event, 1, nullptr, 0, nullptr);
 #endif
 
     if (UNLIKELY(ret != 0)) {
@@ -368,18 +368,18 @@ int32_t TimerStart(const itimerspec *time, void *(*cb)(void *), void *args) {
     std::atomic_fetch_add(&g_total_timer_num, 1U);
 
 #if defined(OS_LINUX)
-    ret = timerfd_settime(timer_fd, 0, time, NULL);
+    ret = timerfd_settime(timer_fd, 0, time, nullptr);
 #elif defined(OS_MACOSX)
-    ret = timerfd_settime_macosx(timer_fd, 0, time, NULL);
+    ret = timerfd_settime_macosx(timer_fd, 0, time, nullptr);
 #endif
 
     if (UNLIKELY(ret != 0)) {
 #if defined(OS_LINUX)
-        if (epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, timer_fd, NULL) != 0) {
+        if (epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, timer_fd, nullptr) != 0) {
 #elif defined(OS_MACOSX)
         struct kevent evt;
-        EV_SET(&evt, timer_fd, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
-        if (kevent(g_epoll_fd, &evt, 1, NULL, 0, NULL) != 0) {
+        EV_SET(&evt, timer_fd, EVFILT_TIMER, EV_DELETE, 0, 0, nullptr);
+        if (kevent(g_epoll_fd, &evt, 1, nullptr, 0, nullptr) != 0) {
 #endif
             LOG(ERROR) << "Failed to delete the timer fd=" << timer_fd << " with errno=" << errno;
         }
@@ -397,8 +397,8 @@ uint32_t GetActiveTimerNum(void) {
 }
 
 void CloseTimerFd(int fd) {
-    g_timer_fd_ctx_map[fd].cb = NULL;
-    g_timer_fd_ctx_map[fd].args = NULL;
+    g_timer_fd_ctx_map[fd].cb = nullptr;
+    g_timer_fd_ctx_map[fd].args = nullptr;
     g_timer_fd_ctx_map[fd].status = TIMER_CONTEXT_NOT_USING;
     g_timer_fd_ctx_map[fd].fd = 0;
     g_timer_fd_ctx_map[fd].periodical = 0;
@@ -421,7 +421,7 @@ void TimerModuleDestroy(void) {
     g_epoll_fd = -1;
     g_total_timer_num = 0;
     g_timer_module_initialized = 0;
-    int32_t ret = pthread_join(g_epoll_execute_thread, NULL);
+    int32_t ret = pthread_join(g_epoll_execute_thread, nullptr);
     if (ret != EOK) {
         LOG(ERROR) << "Failed to join pthread, during destroying timer module. ret=" << ret;
         return;
@@ -437,7 +437,7 @@ RETURN_CODE TimerFdCtxValidate(uint32_t fd) {
         LOG(ERROR) << "TimerFd=" << fd << " has wrong status=" << g_timer_fd_ctx_map[fd].status;
         return UBRING_ERR;
     }
-    if (g_timer_fd_ctx_map[fd].cb == NULL) {
+    if (g_timer_fd_ctx_map[fd].cb == nullptr) {
         LOG(ERROR) << "The callback is not set.";
         return UBRING_ERR;
     }
@@ -457,7 +457,7 @@ static int timerfd_create_macosx(int clockid, int flags) {
 static int timerfd_settime_macosx(int fd, int flags,
                                    const itimerspec *new_value,
                                    itimerspec *old_value) {
-    if (old_value != NULL) {
+    if (old_value != nullptr) {
         memset(old_value, 0, sizeof(itimerspec));
     }
     return 0;
diff --git a/src/brpc/ubshm/ub_endpoint.cpp b/src/brpc/ubshm/ub_endpoint.cpp
index ea965a45b3..45794fdc6e 100644
--- a/src/brpc/ubshm/ub_endpoint.cpp
+++ b/src/brpc/ubshm/ub_endpoint.cpp
@@ -66,7 +66,7 @@ static uint16_t g_ub_impl_version = 1;
 
 static const uint32_t ACK_MSG_UB_OK = 0x1;
 
-static butil::Mutex* g_ubring_resource_mutex = NULL;
+static butil::Mutex* g_ubring_resource_mutex = nullptr;
 
 void HelloMessage::Serialize(void* data) const {
     char* current_pos = static_cast<char*>(data);
@@ -149,7 +149,7 @@ void UBConnect::StartConnect(const Socket* socket,
                                void (*done)(int err, void* data),
                                void* data) {
     auto* ub_transport = static_cast<UBShmTransport*>(socket->_transport.get());
-    CHECK(ub_transport->_ub_ep != NULL);
+    CHECK(ub_transport->_ub_ep != nullptr);
     SocketUniquePtr s;
     if (Socket::Address(socket->id(), &s) != 0) {
         return;
@@ -211,7 +211,7 @@ static void TryReadOnTcpDuringRdmaEst(Socket* s) {
 void UBShmEndpoint::OnNewDataFromTcp(Socket* m) {
     auto* ub_transport = static_cast<UBShmTransport*>(m->_transport.get());
     UBShmEndpoint* ep = ub_transport->GetUBShmEp();
-    CHECK(ep != NULL);
+    CHECK(ep != nullptr);
 
     int progress = Socket::PROGRESS_INIT;
     while (true) {
@@ -267,7 +267,7 @@ bool HelloNegotiationValid(HelloMessage& msg) {
 static const int WAIT_TIMEOUT_MS = 50;
 
 int UBShmEndpoint::ReadFromFd(void* data, size_t len) {
-    CHECK(data != NULL);
+    CHECK(data != nullptr);
     int nr = 0;
     size_t received = 0;
     do {
@@ -295,7 +295,7 @@ int UBShmEndpoint::ReadFromFd(void* data, size_t len) {
 }
 
 int UBShmEndpoint::WriteToFd(void* data, size_t len) {
-    CHECK(data != NULL);
+    CHECK(data != nullptr);
     int nw = 0;
     size_t written = 0;
     do {
@@ -341,14 +341,14 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
     ep->_state = C_ALLOC_SHM;
     auto* ub_transport = static_cast<UBShmTransport*>(s->_transport.get());
     size_t local_shm_len = (size_t)(FLAGS_data_queue_size) * MB_TO_BYTE;
-    SHM local_trx_shm = {NULL, local_shm_len, 0, {0}, (uint32_t)s->fd()};
+    SHM local_trx_shm = {nullptr, local_shm_len, 0, {0}, (uint32_t)s->fd()};
     auto shm_name_str = butil::endpoint2str(s->local_side());
     const char* shm_name = shm_name_str.c_str();
     if (ep->AllocateClientResources(&local_trx_shm, shm_name) < 0) {
         LOG(WARNING) << "Fallback to tcp:" << s->description();
         ub_transport->_ub_state = UBShmTransport::UB_OFF;
         ep->_state = FALLBACK_TCP;
-        return NULL;
+        return nullptr;
     }
 
     ep->_state = C_HELLO_SEND;
@@ -366,7 +366,7 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
     LOG_IF(INFO, FLAGS_ub_trace_verbose) << "client handshake message : " << local_msg.toString();
 
@@ -377,14 +377,14 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
     if (memcmp(data, MAGIC_STR, MAGIC_STR_LEN) != 0) {
         LOG(WARNING) << "Read unexpected data during handshake:" << s->description();
         s->SetFailed(EPROTO, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(EPROTO));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     if (ep->ReadFromFd(data, HELLO_MSG_LEN_MIN - MAGIC_STR_LEN) < 0) {
@@ -393,7 +393,7 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
     HelloMessage remote_msg;
     remote_msg.Deserialize(data);
@@ -403,7 +403,7 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
         s->SetFailed(EPROTO, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(EPROTO));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     if (remote_msg.msg_len > HELLO_MSG_LEN_MIN) {
@@ -438,7 +438,7 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     if (ub_transport->_ub_state == UBShmTransport::UB_ON) {
@@ -454,7 +454,7 @@ void* UBShmEndpoint::ProcessHandshakeAtClient(void* arg) {
 
     errno = 0;
 
-    return NULL;
+    return nullptr;
 }
 
 void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
@@ -473,7 +473,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
     auto* ub_transport = static_cast<UBShmTransport*>(s->_transport.get());
     if (memcmp(data, MAGIC_STR, MAGIC_STR_LEN) != 0) {
@@ -484,7 +484,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         ep->_state = FALLBACK_TCP;
         ub_transport->_ub_state = UBShmTransport::UB_OFF;
         ep->TryReadOnTcp();
-        return NULL;
+        return nullptr;
     }
 
     if (ep->ReadFromFd(data, g_ub_hello_msg_len - MAGIC_STR_LEN) < 0) {
@@ -493,7 +493,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     HelloMessage remote_msg;
@@ -505,7 +505,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         s->SetFailed(EPROTO, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(EPROTO));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
     if (remote_msg.msg_len > HELLO_MSG_LEN_MIN) {
         // TODO: Read Hello Message customized header
@@ -518,17 +518,17 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         ub_transport->_ub_state = UBShmTransport::UB_OFF;
     } else {
         ep->_state = S_ALLOC_SHM;
-        ubring::SHM remote_trx_shm = {NULL, remote_msg.len, 0, {0}, (uint32_t)ep->_socket->fd()};
+        ubring::SHM remote_trx_shm = {nullptr, remote_msg.len, 0, {0}, (uint32_t)ep->_socket->fd()};
         strncpy(remote_trx_shm.name, remote_msg.shm_name, SHM_MAX_NAME_BUFF_LEN);
 
         size_t local_shm_len = (size_t)(FLAGS_data_queue_size) * MB_TO_BYTE;
         // server-side shared memory name
-        ubring::SHM local_trx_shm = {NULL, local_shm_len, 0, {0}, (uint32_t)ep->_socket->fd()};
+        ubring::SHM local_trx_shm = {nullptr, local_shm_len, 0, {0}, (uint32_t)ep->_socket->fd()};
         char client_name[SHM_MAX_NAME_BUFF_LEN];
         strncpy(client_name, remote_msg.shm_name, SHM_MAX_NAME_BUFF_LEN);
 
         char *client_ip_port = strrchr(client_name, '_');
-        if (client_ip_port != NULL) {
+        if (client_ip_port != nullptr) {
             *client_ip_port = '\0';
         }
         int result = snprintf(local_trx_shm.name, SHM_MAX_NAME_BUFF_LEN, "%s_%s",
@@ -564,7 +564,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ub handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     ep->_state = S_ACK_WAIT;
@@ -574,7 +574,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
         s->SetFailed(saved_errno, "Fail to complete ubring handshake from %s: %s",
                 s->description().c_str(), berror(saved_errno));
         ep->_state = FAILED;
-        return NULL;
+        return nullptr;
     }
 
     uint32_t* tmp = (uint32_t*)data;
@@ -586,7 +586,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
             s->SetFailed(EPROTO, "Fail to complete ub handshake from %s: %s",
                     s->description().c_str(), berror(EPROTO));
             ep->_state = FAILED;
-            return NULL;
+            return nullptr;
         } else {
             ub_transport->_ub_state = UBShmTransport::UB_ON;
             ep->_state = ESTABLISHED;
@@ -602,7 +602,7 @@ void* UBShmEndpoint::ProcessHandshakeAtServer(void* arg) {
     }
     ep->TryReadOnTcp();
 
-    return NULL;
+    return nullptr;
 }
 
 bool UBShmEndpoint::IsWritable() const {
@@ -671,7 +671,7 @@ int UBShmEndpoint::AllocateClientResources(ubring::SHM* local_trx_shm, const cha
         return 0;
     }
 
-    CHECK(_ub_ring == NULL);
+    CHECK(_ub_ring == nullptr);
     // TODO: Pooling management
     _ub_ring = new UBRing();
 
@@ -696,7 +696,7 @@ int UBShmEndpoint::AllocateServerResources(ubring::SHM* remote_trx_shm, ubring::
         return 0;
     }
 
-    CHECK(_ub_ring == NULL);
+    CHECK(_ub_ring == nullptr);
     // TODO: Pooling management
     _ub_ring = new UBRing();
 
@@ -725,7 +725,7 @@ void UBShmEndpoint::DeallocateResources() {
     if (INVALID_SOCKET_ID != _cq_sid) {
         SocketUniquePtr s;
         if (Socket::Address(_cq_sid, &s) == 0) {
-            s->_user = NULL;
+            s->_user = nullptr;
             s->_fd = -1;
             s->SetFailed();
         }
@@ -914,7 +914,7 @@ void UBShmEndpoint::PollingModeRelease(bthread_tag_t tag) {
     auto& running = group.running;
     running.store(false, std::memory_order_relaxed);
     for (int i = 0; i < FLAGS_ub_poller_num; ++i) {
-        bthread_join(pollers[i].tid, NULL);
+        bthread_join(pollers[i].tid, nullptr);
     }
 }
 
diff --git a/src/brpc/ubshm/ub_endpoint.h b/src/brpc/ubshm/ub_endpoint.h
index bf9e61c5d7..03c5134522 100644
--- a/src/brpc/ubshm/ub_endpoint.h
+++ b/src/brpc/ubshm/ub_endpoint.h
@@ -68,8 +68,8 @@ class UBConnect : public AppConnect {
 
 private:
     void Run();
-    void (*_done)(int, void*){NULL};
-    void* _data{NULL};
+    void (*_done)(int, void*){nullptr};
+    void* _data{nullptr};
 };
 
 class BAIDU_CACHELINE_ALIGNMENT UBShmEndpoint : public SocketUser {
diff --git a/src/brpc/ubshm/ub_helper.cpp b/src/brpc/ubshm/ub_helper.cpp
index b88e656adc..230ca71bac 100644
--- a/src/brpc/ubshm/ub_helper.cpp
+++ b/src/brpc/ubshm/ub_helper.cpp
@@ -31,7 +31,7 @@
 namespace brpc {
 namespace ubring {
 
-void* g_handle_ub = NULL;
+void* g_handle_ub = nullptr;
 bool g_skip_ub_init = false;
 
 butil::atomic<bool> g_ub_available(false);
diff --git a/src/brpc/ubshm/ub_ring.cpp b/src/brpc/ubshm/ub_ring.cpp
index 7008314437..72df015409 100644
--- a/src/brpc/ubshm/ub_ring.cpp
+++ b/src/brpc/ubshm/ub_ring.cpp
@@ -122,7 +122,7 @@ RETURN_CODE UBRing::UbrTrxClose() {
 }
 
 RETURN_CODE UBRing::UbrAddCloseTimer() {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "Trx add close timer failed, trx is null.";
         return UBRING_ERR;
     }
@@ -196,7 +196,7 @@ void* UBRing::UbrTrxCloseCallback(void* args) {
 }
 
 RETURN_CODE UBRing::UbrAddHBTimer() {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "Trx add heartbeat timer failed, trx is null.";
         return UBRING_ERR;
     }
@@ -227,7 +227,7 @@ RETURN_CODE UBRing::UbrPassiveClearTrx(UbrTrx *trx, int fd, PASSIVE_DISC_TYPE ty
     trx->ubr_tx.trx_state = UBR_STATE_CLOSED;
     trx->ubr_rx.trx_state = UBR_STATE_CLOSED;
     DeleteTimerSafe((uint32_t)trx->timer_fd);
-    const char *type_name = NULL;
+    const char *type_name = nullptr;
     if (type == UBR_HEARTBEAT) {
         DeleteTimer((uint32_t)trx->hb_timer_fd);
         type_name = "Trx heartbeat";
@@ -253,42 +253,42 @@ RETURN_CODE UBRing::UbrPassiveClearTrx(UbrTrx *trx, int fd, PASSIVE_DISC_TYPE ty
 void* UBRing::UbrTrxHBCallback(void* args) {
     auto* trx = (UbrTrx*) args;
     if (UNLIKELY(UbrTrxCallbackCheck(trx) != UBRING_OK)) {
-        return NULL;
+        return nullptr;
     }
 
     auto* local_data_status = (UbrDataStatusQMsg *)trx->ubr_tx.local_data_status_q.addr;
     auto* remote_data_status = (UbrDataStatusQMsg *)trx->ubr_rx.remote_data_status_q.addr;
-    if (UNLIKELY(local_data_status == NULL || remote_data_status == NULL)) {
+    if (UNLIKELY(local_data_status == nullptr || remote_data_status == nullptr)) {
         LOG(ERROR) << "Heartbeat error, datastatus is NULL.";
-        return NULL;
+        return nullptr;
     }
 
     if (trx->ubr_tx.trx_state != UBR_STATE_CONNECTED || trx->ubr_rx.trx_state != UBR_STATE_CONNECTED) {
         LOG_EVERY_SECOND(INFO) << "Heartbeat cannot be started, wait connected state.";
-        return NULL;
+        return nullptr;
     }
 
     remote_data_status->heart_beat = 1;
     if (local_data_status->heart_beat == 1) {
         local_data_status->heart_beat = 0;
         trx->ubr_tx.hb_retry_cnt = 0;
-        return NULL;
+        return nullptr;
     }
 
     ++trx->ubr_tx.hb_retry_cnt;
     if (trx->ubr_tx.hb_retry_cnt <= FLAGS_ub_hb_retry_cnt) {
-        return NULL;
+        return nullptr;
     }
 
     int fd = (int)trx->local_shm.fd;
     LOG(INFO) << "Hlc heartbeat, start to clear trx resource. hb_timer_fd=" << fd << ", shm_name=" << trx->local_shm.name;
     UbrPassiveClearTrx(trx, fd, UBR_HEARTBEAT);
     LOG(INFO) << "Hlc heartbeat clear trx resource finish.";
-    return NULL;
+    return nullptr;
 }
 
 RETURN_CODE UBRing::UbrAddAsynClearTimer(UbrTrx *trx) {
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Trx add close timer failed, trx is null.";
         return UBRING_ERR;
     }
@@ -314,9 +314,9 @@ RETURN_CODE UBRing::UbrAddAsynClearTimer(UbrTrx *trx) {
 void *UBRing::UbrAsynClearCallback(void *args)
 {
     auto* trx = (UbrTrx*) args;
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Trx close, trx is null.";
-        return NULL;
+        return nullptr;
     }
 
     if (UNLIKELY(UbrTrxFreeShm(trx) != UBRING_OK)) {
@@ -326,7 +326,7 @@ void *UBRing::UbrAsynClearCallback(void *args)
     if (UNLIKELY(UBRingManager::ReleaseUbrTrxFromMgr(trx) != UBRING_OK)) {
         LOG(ERROR) << "Trx close, release shm " << trx->local_shm.name << " trx failed.";
     }
-    return NULL;
+    return nullptr;
 }
 
 int UBRing::UbrTrxSend(const void *buf, uint32_t buf_len)
@@ -539,11 +539,11 @@ ssize_t UBRing::UbrTrxReadvBlockMode(const struct iovec *iov, int iovcnt)
 
 RETURN_CODE UBRing::IsUbrTrxReadable(uint32_t ep_event)
 {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "The trx to be checked is NULL.";
         return UBRING_ERR;
     }
-    if (UNLIKELY(_trx->local_shm.addr == NULL)) {
+    if (UNLIKELY(_trx->local_shm.addr == nullptr)) {
         LOG(ERROR) << "The trx local_shm to be checked is NULL.";
         return UBRING_ERR;
     }
@@ -574,19 +574,19 @@ RETURN_CODE UBRing::IsUbrTrxReadable(uint32_t ep_event)
 
 RETURN_CODE UBRing::IsUbrTrxWriteable(uint32_t ep_event)
 {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "The trx to be checked is NULL.";
         return UBRING_ERR;
     }
-    if (UNLIKELY(_trx->local_shm.addr == NULL)) {
+    if (UNLIKELY(_trx->local_shm.addr == nullptr)) {
         LOG(ERROR) << "The trx local_shm to be checked is NULL.";
         return UBRING_ERR;
     }
-    if (UNLIKELY((UbrEventQMsg *)_trx->ubr_tx.local_tx_event_q.addr == NULL)) {
+    if (UNLIKELY((UbrEventQMsg *)_trx->ubr_tx.local_tx_event_q.addr == nullptr)) {
         LOG(ERROR) << "The trx local_tx_event_q addr is NULL.";
         return UBRING_ERR;
     }
-    if (UNLIKELY((UbrEventQMsg *)_trx->ubr_tx.local_data_status_q.addr == NULL)) {
+    if (UNLIKELY((UbrEventQMsg *)_trx->ubr_tx.local_data_status_q.addr == nullptr)) {
         LOG(ERROR) << "The trx local_data_status_q addr is NULL.";
         return UBRING_ERR;
     }
@@ -628,7 +628,7 @@ RETURN_CODE UBRing::UbrSetTimeout(UbrTaskStep task_type, int timeout)
 
 RETURN_CODE UBRing::UbrTrxFreeShm(UbrTrx *trx)
 {
-    if (trx == NULL) {
+    if (trx == nullptr) {
         LOG(ERROR) << "Trx is NULL.";
         return UBRING_ERR;
     }
@@ -650,7 +650,7 @@ RETURN_CODE UBRing::UbrTrxFreeShm(UbrTrx *trx)
     }
 
     RETURN_CODE remote_rc = UBRING_OK;
-    if (trx->remote_shm.addr != NULL) {
+    if (trx->remote_shm.addr != nullptr) {
         remote_rc = ShmRemoteFree(&trx->remote_shm);
     }
     if (remote_rc != UBRING_OK) {
@@ -662,7 +662,7 @@ RETURN_CODE UBRing::UbrTrxFreeShm(UbrTrx *trx)
 
 RETURN_CODE UBRing::UbrUnlinkLocalShm()
 {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         return UBRING_ERR;
     }
     RETURN_CODE rc = ShmFree(&_trx->local_shm);
@@ -675,7 +675,7 @@ RETURN_CODE UBRing::UbrUnlinkLocalShm()
 
 void UBRing::PreWriteAddr(uint8_t *addr, size_t len)
 {
-    if (addr == NULL) {
+    if (addr == nullptr) {
         return;
     }
 
@@ -699,7 +699,7 @@ void UBRing::PreWriteAddr(uint8_t *addr, size_t len)
 
 void UBRing::PrewriteUbrTx(UbrTx *tx)
 {
-    if (tx == NULL) {
+    if (tx == nullptr) {
         return;
     }
     PreWriteAddr(tx->remote_data_q.addr, tx->capacity * sizeof(UbrMsgFormat));
@@ -707,7 +707,7 @@ void UBRing::PrewriteUbrTx(UbrTx *tx)
 
 void UBRing::PrewriteUbrRx(UbrRx *rx)
 {
-    if (rx == NULL) {
+    if (rx == nullptr) {
         return;
     }
     PreWriteAddr(rx->local_data_q.addr, rx->capacity * sizeof(UbrMsgFormat));
@@ -715,11 +715,11 @@ void UBRing::PrewriteUbrRx(UbrRx *rx)
 
 RETURN_CODE UBRing::UbrTrxMapLocalShm(SHM *local_shm)
 {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "Trx map Shared memory failed, trx is null.";
         return UBRING_ERR;
     }
-    if (UNLIKELY(local_shm == NULL || local_shm->addr == NULL)) {
+    if (UNLIKELY(local_shm == nullptr || local_shm->addr == nullptr)) {
         LOG(ERROR) << "Trx map Shared memory failed, local_shm is null or addr is NULL.";
         return UBRING_ERR;
     }
@@ -738,11 +738,11 @@ RETURN_CODE UBRing::UbrTrxMapLocalShm(SHM *local_shm)
 
 RETURN_CODE UBRing::UbrTrxMapRemoteShm(SHM *remote_shm)
 {
-    if (UNLIKELY(_trx == NULL)) {
+    if (UNLIKELY(_trx == nullptr)) {
         LOG(ERROR) << "Trx map Shared memory failed, trx is null.";
         return UBRING_ERR;
     }
-    if (UNLIKELY(remote_shm == NULL || remote_shm->addr == NULL)) {
+    if (UNLIKELY(remote_shm == nullptr || remote_shm->addr == nullptr)) {
         LOG(ERROR) << "Trx map Shared memory failed, remote_shm is null or addr is NULL.";
         return UBRING_ERR;
     }
@@ -866,7 +866,7 @@ RETURN_CODE UBRing::UbrMapRemoteShmAddTimer(SHM *local_trx_shm, const char *loca
 
     size_t remote_server_len = UBR_MSG_LEN * (((UbrDataStatusQMsg *)(_trx->ubr_tx.local_data_status_q.addr))->tail + 1) +
                              UBR_MSG_LEN * ((DATAQ_ADDR_OFFSET / UBR_MSG_LEN) + 1);
-    SHM remote_trx_shm = {NULL, remote_server_len, 0, {0}, local_trx_shm->fd};
+    SHM remote_trx_shm = {nullptr, remote_server_len, 0, {0}, local_trx_shm->fd};
     int result = snprintf(remote_trx_shm.name,
         SHM_MAX_NAME_BUFF_LEN,
         "%s_%s_%s",
@@ -906,7 +906,7 @@ RETURN_CODE UBRing::UbrMapRemoteShmAddTimer(SHM *local_trx_shm, const char *loca
 
 RETURN_CODE UBRing::ApplyAndMapLocalShm(SHM *local_trx_shm, const char *local_name)
 {
-    if (UNLIKELY(_trx == NULL || local_trx_shm == NULL)) {
+    if (UNLIKELY(_trx == nullptr || local_trx_shm == nullptr)) {
         LOG(ERROR) << "Trx map Shared memory failed, trx is null, local_name=" << local_name;
         return UBRING_ERR;
     }
@@ -988,7 +988,7 @@ RETURN_CODE UBRing::WritevHasEnoughSpace(size_t buf_len)
 
 RETURN_CODE UBRing::UbrClearResourceCheck(UbrTrx *trx, uint64_t start_time, UbrCloseType close_type)
 {
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Trx close failed, trx is null.";
         return UBRING_ERR;
     }
@@ -1031,7 +1031,7 @@ RETURN_CODE UBRing::ClearTrxResource(UbrTrx *trx, uint64_t start_time, UbrCloseT
 
 RETURN_CODE UBRing::UbrTrxCloseCheck(UbrTrx *trx)
 {
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Trx close failed, client trx is null.";
         return UBRING_ERR;
     }
diff --git a/src/brpc/ubshm/ub_ring.h b/src/brpc/ubshm/ub_ring.h
index c08c90801a..f1a5cf14ff 100644
--- a/src/brpc/ubshm/ub_ring.h
+++ b/src/brpc/ubshm/ub_ring.h
@@ -96,11 +96,11 @@ class UBRing : public butil::IReader {
 
     static inline RETURN_CODE CheckTrxConnectParam(const char *listener_name, const char *local_name)
     {
-        if (UNLIKELY(listener_name == NULL)) {
+        if (UNLIKELY(listener_name == nullptr)) {
             LOG(ERROR) << "The request listener name is null.";
             return UBRING_ERR;
         }
-        if (UNLIKELY(local_name == NULL)) {
+        if (UNLIKELY(local_name == nullptr)) {
             LOG(ERROR) << "The request trx shared memory name is null.";
             return UBRING_ERR;
         }
@@ -126,12 +126,12 @@ class UBRing : public butil::IReader {
     }
     static RETURN_CODE CheckTrxRecvParam(UbrTrx *trx, const void *buf, uint32_t buf_len)
     {
-        if (UNLIKELY(trx == NULL)) {
+        if (UNLIKELY(trx == nullptr)) {
             LOG(ERROR) << "Trx recv failed, trx is null.";
             return UBRING_ERR;
         }
 
-        if (UNLIKELY((UbrEventQMsg *)trx->ubr_rx.local_rx_event_q.addr == NULL)) {
+        if (UNLIKELY((UbrEventQMsg *)trx->ubr_rx.local_rx_event_q.addr == nullptr)) {
             LOG(ERROR) << "Trx send failed, local_tx_event_q addr is NULL.";
             return UBRING_ERR;
         }
@@ -140,7 +140,7 @@ class UBRing : public butil::IReader {
             LOG(ERROR) << "Trx recv failed, trx is not connected statep=" << trx->ubr_rx.trx_state;
             return UBR_NOT_CONNECTED;
         }
-        if (UNLIKELY(buf == NULL)) {
+        if (UNLIKELY(buf == nullptr)) {
             LOG(ERROR) << "Trx recv failed, buf is null.";
             return UBRING_ERR;
         }
@@ -167,19 +167,19 @@ class UBRing : public butil::IReader {
 
     static RETURN_CODE UbrTrxCallbackCheck(UbrTrx *trx)
     {
-        if (trx == NULL) {
+        if (trx == nullptr) {
             LOG(ERROR) << "Trx close callback failed, trx is null.";
             return UBRING_ERR;
         }
-        if (UNLIKELY(trx->local_shm.addr == NULL)) {
+        if (UNLIKELY(trx->local_shm.addr == nullptr)) {
             LOG(ERROR) << "Trx close failed, local_shm addr is NULL.";
             return UBRING_ERR;
         }
-        if (UNLIKELY(trx->ubr_rx.local_rx_event_q.addr == NULL)) {
+        if (UNLIKELY(trx->ubr_rx.local_rx_event_q.addr == nullptr)) {
             LOG(ERROR) << "Trx close failed, local_rx_event_q addr is NULL.";
             return UBRING_ERR;
         }
-        if (UNLIKELY(trx->ubr_tx.local_tx_event_q.addr == NULL)) {
+        if (UNLIKELY(trx->ubr_tx.local_tx_event_q.addr == nullptr)) {
             LOG(ERROR) << "Trx close failed, local_tx_event_q addr is NULL.";
             return UBRING_ERR;
         }
diff --git a/src/brpc/ubshm/ub_ring_manager.cpp b/src/brpc/ubshm/ub_ring_manager.cpp
index 6656e33726..64f2434eba 100644
--- a/src/brpc/ubshm/ub_ring_manager.cpp
+++ b/src/brpc/ubshm/ub_ring_manager.cpp
@@ -36,7 +36,7 @@ uint64_t g_ub_event_cnt = 0;
 uint64_t g_ubr_listener_num = 0;
 
 RETURN_CODE UBRingManager::GetUbrDealMsgMaxCnt(const uint32_t capacity, uint32_t *deal_msg_max_cnt) {
-    if (UNLIKELY(deal_msg_max_cnt == NULL)) {
+    if (UNLIKELY(deal_msg_max_cnt == nullptr)) {
         LOG(ERROR) << "Get update factor failed, deal_msg_max_cnt is null.";
         return UBRING_ERR;
     }
@@ -52,8 +52,8 @@ RETURN_CODE UBRingManager::UbrMgrDefault()
 {
     g_ubr_mgr.trx_num = 0;
     g_ubr_mgr.trx_cap = FLAGS_ubr_max_managed_num;
-    g_ubr_mgr.trx_mgr_unit_status = NULL;
-    g_ubr_mgr.trx_mgr = NULL;
+    g_ubr_mgr.trx_mgr_unit_status = nullptr;
+    g_ubr_mgr.trx_mgr = nullptr;
     return UBRING_OK;
 }
 
@@ -68,8 +68,8 @@ RETURN_CODE UBRingManager::UbrMgrInit() {
     g_ubr_mgr.trx_mgr = (UbrTrx *)malloc(trx_mgr_size);
     size_t trx_mgr_status_size = g_ubr_mgr.trx_cap * sizeof(UbrMgrUnitStatus);
     g_ubr_mgr.trx_mgr_unit_status = (UbrMgrUnitStatus *)malloc(trx_mgr_status_size);
-    if (UNLIKELY(g_ubr_mgr.trx_mgr == NULL ||
-                 g_ubr_mgr.trx_mgr_unit_status == NULL)) {
+    if (UNLIKELY(g_ubr_mgr.trx_mgr == nullptr ||
+                 g_ubr_mgr.trx_mgr_unit_status == nullptr)) {
         LOG(ERROR) << "Ubr manager memory allocation failed.";
         UbrMgrFini();
         return UBRING_ERR;
@@ -96,12 +96,12 @@ void UBRingManager::UbrMgrFini() {
 }
 
 RETURN_CODE UBRingManager::AcquireUbrTrxFromMgr(UbrTrx **trx) {
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Acquire trx failed, trx is null.";
         return UBRING_ERR;
     }
 
-    if (UNLIKELY(g_ubr_mgr.trx_mgr == NULL)) {
+    if (UNLIKELY(g_ubr_mgr.trx_mgr == nullptr)) {
         LOG(ERROR) << "Acquire trx failed, trx_mgr is null.";
         return UBRING_ERR;
     }
@@ -131,17 +131,17 @@ RETURN_CODE UBRingManager::AcquireUbrTrxFromMgr(UbrTrx **trx) {
 }
 
 RETURN_CODE UBRingManager::ReleaseUbrTrxFromMgr(UbrTrx *trx) {
-    if (UNLIKELY(trx == NULL)) {
+    if (UNLIKELY(trx == nullptr)) {
         LOG(ERROR) << "Release trx failed, trx is null.";
         return UBRING_ERR;
     }
 
-    trx->local_shm.addr = NULL;
-    trx->ubr_tx.local_tx_event_q.addr = NULL;
-    trx->ubr_tx.local_data_status_q.addr = NULL;
-    trx->ubr_rx.local_rx_event_q.addr = NULL;
-    trx->ubr_rx.remote_data_status_q.addr = NULL;
-    if (UNLIKELY(g_ubr_mgr.trx_mgr == NULL)) {
+    trx->local_shm.addr = nullptr;
+    trx->ubr_tx.local_tx_event_q.addr = nullptr;
+    trx->ubr_tx.local_data_status_q.addr = nullptr;
+    trx->ubr_rx.local_rx_event_q.addr = nullptr;
+    trx->ubr_rx.remote_data_status_q.addr = nullptr;
+    if (UNLIKELY(g_ubr_mgr.trx_mgr == nullptr)) {
         LOG(ERROR) << "Release trx failed, trx_mgr is null.";
         return UBRING_ERR;
     }
@@ -167,14 +167,14 @@ void UBRingManager::LinkInfoInit(void) {
 
     size_t link_info_mgr_size = FLAGS_ubr_max_managed_num * sizeof(UbrLinkInfo);
     g_link_info_mgr.all_link_info = (UbrLinkInfo*) malloc(link_info_mgr_size);
-    if (g_link_info_mgr.all_link_info == NULL) {
+    if (g_link_info_mgr.all_link_info == nullptr) {
         LOG(ERROR) << "all_link_info is NULL";
         LinkInfoFini();
         return;
     }
 
     g_link_info_mgr.link_mgr_unit_status = (UbrMgrUnitStatus*) malloc(link_info_mgr_size);
-    if (g_link_info_mgr.link_mgr_unit_status == NULL) {
+    if (g_link_info_mgr.link_mgr_unit_status == nullptr) {
         LinkInfoFini();
         return;
     }
@@ -184,7 +184,7 @@ void UBRingManager::LinkInfoInit(void) {
 }
 
 void UBRingManager::LinkInfoFini(void) {
-    if (g_link_info_mgr.link_mgr_unit_status == NULL || g_link_info_mgr.all_link_info == NULL) {
+    if (g_link_info_mgr.link_mgr_unit_status == nullptr || g_link_info_mgr.all_link_info == nullptr) {
         LOG(ERROR) << "LinkInfo is NULL";
         return;
     }
@@ -198,12 +198,12 @@ void UBRingManager::LinkInfoFini(void) {
 }
 
 void UBRingManager::AcquireLinkInfoToMgr(const char *listener_name, UbrTrx *trx) {
-    if (listener_name == NULL || trx == NULL) {
+    if (listener_name == nullptr || trx == nullptr) {
         LOG(ERROR) << "LinkInfo acquire fail.";
         return;
     }
 
-    if (g_link_info_mgr.link_mgr_unit_status == NULL || g_link_info_mgr.all_link_info == NULL) {
+    if (g_link_info_mgr.link_mgr_unit_status == nullptr || g_link_info_mgr.all_link_info == nullptr) {
         LOG(ERROR) << "LinkInfo is NULL.";
         return;
     }
@@ -220,7 +220,7 @@ void UBRingManager::AcquireLinkInfoToMgr(const char *listener_name, UbrTrx *trx)
 }
 
 void UBRingManager::ReleaseLinkInfoFromMgr(UbrTrx *trx) {
-    if (trx == NULL || g_link_info_mgr.link_mgr_unit_status == NULL) {
+    if (trx == nullptr || g_link_info_mgr.link_mgr_unit_status == nullptr) {
         LOG(ERROR) << "LinkInfo release fail.";
         return;
     }
@@ -235,11 +235,11 @@ void UBRingManager::ReleaseLinkInfoFromMgr(UbrTrx *trx) {
 
 int32_t UBRingManager::UbEventCallback(const char *shm_name)
 {
-    if (UNLIKELY(shm_name == NULL)) {
+    if (UNLIKELY(shm_name == nullptr)) {
         LOG(ERROR) << "Ub event callback failed, shm name is null.";
         return UBRING_ERR;
     }
-    if (UNLIKELY(g_ubr_mgr.trx_mgr == NULL)) {
+    if (UNLIKELY(g_ubr_mgr.trx_mgr == nullptr)) {
         LOG(ERROR) << "Ub event callback failed, trx mgr is null.";
         return UBRING_ERR;
     }
diff --git a/src/brpc/ubshm/ubs_mem/ubs_mem.h b/src/brpc/ubshm/ubs_mem/ubs_mem.h
index 6466dba67f..d5c1ab6814 100644
--- a/src/brpc/ubshm/ubs_mem/ubs_mem.h
+++ b/src/brpc/ubshm/ubs_mem/ubs_mem.h
@@ -122,7 +122,7 @@ SHMEM_API int ubsmem_shmem_deallocate(const char *name);
 
 /**
  * Map item in UBSMSHMEM to the local virtual address space, and return its pointer.
- * @param addr - The starting address for the new mapping is specified in addr, If addr is NULL, then
+ * @param addr - The starting address for the new mapping is specified in addr, If addr is nullptr, then
  * the kernel chooses the (page-aligned) address at which to create the mapping
  * @param length - The length argument specifies the length of the mapping (which must be greater than 0)
  * @param prot - same as mmap, describes the desired memory protection of the mapping (and must not conflict with