[4.1] add [[nodiscard]] on LockGuard

deps/oblib/src/lib/lock/ob_bucket_lock.h

@@ -68,7 +68,7 @@ private:
 class ObBucketRLockGuard final
 {
 public:
-  ObBucketRLockGuard(ObBucketLock &lock, const uint64_t bucket_index)
+  [[nodiscard]] ObBucketRLockGuard(ObBucketLock &lock, const uint64_t bucket_index)
      : lock_(lock),
        index_(bucket_index),
        ret_(OB_SUCCESS),
@@ -109,7 +109,7 @@ private:
 class ObBucketWLockGuard final
 {
 public:
-  ObBucketWLockGuard(ObBucketLock &lock, const uint64_t bucket_index)
+  [[nodiscard]] ObBucketWLockGuard(ObBucketLock &lock, const uint64_t bucket_index)
      : lock_(lock),
        index_(bucket_index),
        ret_(OB_SUCCESS),
@@ -150,7 +150,7 @@ private:
 class ObBucketWLockAllGuard final
 {
 public:
-  ObBucketWLockAllGuard(ObBucketLock &lock)
+  [[nodiscard]] ObBucketWLockAllGuard(ObBucketLock &lock)
      : lock_(lock),
        ret_(OB_SUCCESS),
        lock_start_ts_(0)
@@ -189,7 +189,7 @@ private:
 class ObBucketTryWLockAllGuard final
 {
 public:
-  ObBucketTryWLockAllGuard(ObBucketLock &lock)
+  [[nodiscard]] ObBucketTryWLockAllGuard(ObBucketLock &lock)
      : lock_(lock),
        ret_(OB_SUCCESS),
        lock_start_ts_(0)
@@ -234,7 +234,7 @@ private:
 class ObBucketTryRLockAllGuard final
 {
 public:
-  ObBucketTryRLockAllGuard(ObBucketLock &lock)
+  [[nodiscard]] ObBucketTryRLockAllGuard(ObBucketLock &lock)
      : lock_(lock),
        ret_(OB_SUCCESS),
        lock_start_ts_(0)
@@ -279,7 +279,7 @@ private:
 class ObMultiBucketLockGuard final
 {
 public:
-  ObMultiBucketLockGuard(ObBucketLock &lock, const bool is_write_lock);
+  [[nodiscard]] ObMultiBucketLockGuard(ObBucketLock &lock, const bool is_write_lock);
   ~ObMultiBucketLockGuard();
   int lock_multi_buckets(ObIArray<uint64_t> &hash_array);
 private:
@@ -293,7 +293,7 @@ private:
 class ObBucketHashRLockGuard final
 {
 public:
-  ObBucketHashRLockGuard(ObBucketLock &lock, const uint64_t hash_value)
+  [[nodiscard]] ObBucketHashRLockGuard(ObBucketLock &lock, const uint64_t hash_value)
     : guard_(lock, lock.get_bucket_idx(hash_value))
   {
   }
@@ -307,7 +307,7 @@ private:
 class ObBucketHashWLockGuard final
 {
 public:
-  ObBucketHashWLockGuard(ObBucketLock &lock, const uint64_t hash_value)
+  [[nodiscard]] ObBucketHashWLockGuard(ObBucketLock &lock, const uint64_t hash_value)
     : guard_(lock, lock.get_bucket_idx(hash_value))
   {
   }

deps/oblib/src/lib/lock/ob_drw_lock.h

@@ -34,7 +34,7 @@ public:
   class RDLockGuard
   {
   public:
-    explicit RDLockGuard(DRWLock &rwlock): rwlock_(rwlock), ret_(OB_SUCCESS)
+    [[nodiscard]] explicit RDLockGuard(DRWLock &rwlock): rwlock_(rwlock), ret_(OB_SUCCESS)
     {
       if (OB_UNLIKELY(OB_SUCCESS != (ret_ = rwlock_.rdlock()))) {
         COMMON_LOG(WARN, "Fail to read lock, ", K_(ret));
@@ -58,7 +58,7 @@ public:
   class WRLockGuard
   {
   public:
-    explicit WRLockGuard(DRWLock &rwlock): rwlock_(rwlock), ret_(OB_SUCCESS)
+    [[nodiscard]] explicit WRLockGuard(DRWLock &rwlock): rwlock_(rwlock), ret_(OB_SUCCESS)
     {
       if (OB_UNLIKELY(OB_SUCCESS != (ret_ = rwlock_.wrlock()))) {
         COMMON_LOG(WARN, "Fail to write lock, ", K_(ret));

deps/oblib/src/lib/lock/ob_latch.h

@@ -364,7 +364,7 @@ private:
 class ObLatchMutexGuard
 {
 public:
-  ObLatchMutexGuard(ObLatchMutex &lock, const uint32_t latch_id)
+  [[nodiscard]] ObLatchMutexGuard(ObLatchMutex &lock, const uint32_t latch_id)
       : lock_(lock), ret_(OB_SUCCESS)
   {
     if (OB_UNLIKELY(OB_SUCCESS != (ret_ = lock_.lock(latch_id)))) {
@@ -390,7 +390,7 @@ private:
 class ObLatchRGuard
 {
 public:
-  ObLatchRGuard(ObLatch &lock, const uint32_t latch_id)
+  [[nodiscard]] ObLatchRGuard(ObLatch &lock, const uint32_t latch_id)
       : lock_(lock),
         ret_(OB_SUCCESS)
   {
@@ -418,7 +418,7 @@ private:
 class ObLatchWGuard
 {
 public:
-  ObLatchWGuard(ObLatch &lock, const uint32_t latch_id)
+  [[nodiscard]] ObLatchWGuard(ObLatch &lock, const uint32_t latch_id)
       : lock_(lock),
         ret_(OB_SUCCESS)
   {

deps/oblib/src/lib/lock/ob_lock_guard.h

@@ -25,7 +25,7 @@ template <typename LockT>
 class ObLockGuard
 {
 public:
-  explicit ObLockGuard(LockT &lock);
+  [[nodiscard]] explicit ObLockGuard(LockT &lock);
   ~ObLockGuard();
   inline int get_ret() const { return ret_; }
 private:

deps/oblib/src/lib/lock/ob_rwlock.h

@@ -23,7 +23,7 @@ template <class T>
 class ObLockGuardBase
 {
 public:
-  ObLockGuardBase(const T& lock, bool block = true) : lock_(lock)
+  [[nodiscard]] ObLockGuardBase(const T& lock, bool block = true) : lock_(lock)
   {
     acquired_ = !(block ? lock_.lock() : lock_.trylock());
   }
@@ -87,7 +87,7 @@ private:
 class ObRLockGuard
 {
 public:
-  ObRLockGuard(const ObRWLock& rwlock, bool block = true) : guard_((*rwlock.rlock()), block) {}
+  [[nodiscard]] ObRLockGuard(const ObRWLock& rwlock, bool block = true) : guard_((*rwlock.rlock()), block) {}
   ~ObRLockGuard(){}
   bool acquired() { return guard_.acquired(); }
 private:
@@ -97,7 +97,7 @@ private:
 class ObWLockGuard
 {
 public:
-  ObWLockGuard(const ObRWLock& rwlock, bool block = true) : guard_((*rwlock.wlock()), block) {}
+  [[nodiscard]] ObWLockGuard(const ObRWLock& rwlock, bool block = true) : guard_((*rwlock.wlock()), block) {}
   ~ObWLockGuard(){}
   bool acquired() { return guard_.acquired(); }
 private:

deps/oblib/src/lib/lock/ob_tc_rwlock.h

@@ -54,13 +54,13 @@ public:
   enum { WRITE_MASK = 1<<31 };
   struct RLockGuard
   {
-    explicit RLockGuard(TCRWLock& lock): lock_(lock) { lock_.rdlock(); }
+    [[nodiscard]] explicit RLockGuard(TCRWLock& lock): lock_(lock) { lock_.rdlock(); }
     ~RLockGuard() { lock_.rdunlock(); }
     TCRWLock& lock_;
   };
   struct RLockGuardWithTimeout
   {
-    explicit RLockGuardWithTimeout(TCRWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
+    [[nodiscard]] explicit RLockGuardWithTimeout(TCRWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
     {
       if (OB_FAIL(lock_.rdlock(abs_timeout_us))) {
         need_unlock_ = false;
@@ -80,13 +80,13 @@ public:
   };
   struct WLockGuard
   {
-    explicit WLockGuard(TCRWLock& lock): lock_(lock) { lock_.wrlock(); }
+    [[nodiscard]] explicit WLockGuard(TCRWLock& lock): lock_(lock) { lock_.wrlock(); }
     ~WLockGuard() { lock_.wrunlock(); }
     TCRWLock& lock_;
   };
   struct WLockGuardWithTimeout
   {
-    explicit WLockGuardWithTimeout(TCRWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
+    [[nodiscard]] explicit WLockGuardWithTimeout(TCRWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
     {
       if (OB_FAIL(lock_.wrlock(abs_timeout_us))) {
         need_unlock_ = false;
@@ -106,7 +106,7 @@ public:
   };
   struct WLockGuardWithRetry
   {
-    explicit WLockGuardWithRetry(TCRWLock &lock, const int64_t abs_timeout_us) : lock_(lock)
+    [[nodiscard]] explicit WLockGuardWithRetry(TCRWLock &lock, const int64_t abs_timeout_us) : lock_(lock)
     {
       lock_.wrlock_with_retry(abs_timeout_us);
     }
@@ -115,7 +115,7 @@ public:
   };
   struct WLockGuardWithRetryInterval
   {
-    explicit WLockGuardWithRetryInterval(TCRWLock &lock,
+    [[nodiscard]] explicit WLockGuardWithRetryInterval(TCRWLock &lock,
                                          const int64_t try_thresold_us,
                                          const int64_t retry_interval_us)
       : lock_(lock)
@@ -287,7 +287,7 @@ private:
 class TCWLockGuard
 {
 public:
-  explicit TCWLockGuard(const TCRWLock &lock)
+  [[nodiscard]] explicit TCWLockGuard(const TCRWLock &lock)
       : lock_(const_cast<TCRWLock&>(lock)), ret_(OB_SUCCESS)
   {
     if (OB_UNLIKELY(OB_SUCCESS != (ret_ = lock_.wrlock()))) {
@@ -313,7 +313,7 @@ private:
 class TCRLockGuard
 {
 public:
-  explicit TCRLockGuard(const TCRWLock &lock)
+  [[nodiscard]] explicit TCRLockGuard(const TCRWLock &lock)
       : lock_(const_cast<TCRWLock&>(lock)), ret_(OB_SUCCESS), slot_id_(0)
   {
     if (OB_UNLIKELY(OB_SUCCESS != (ret_ = lock_.rdlock(INT64_MAX, slot_id_)))) {
@@ -342,7 +342,7 @@ typedef TCRWLock RWLock;
 class RWLock
 {
 public:
-  struct RLockGuard
+  [[nodiscard]]  struct RLockGuard
   {
     explicit RLockGuard(RWLock& lock): lock_(lock) { lock_.rdlock(); }
     ~RLockGuard() { lock_.rdunlock(); }
@@ -350,7 +350,7 @@ public:
   };
   struct RLockGuardWithTimeout
   {
-    explicit RLockGuardWithTimeout(RWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
+    [[nodiscard]]  explicit RLockGuardWithTimeout(RWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
     {
       if (OB_FAIL(lock_.rdlock(abs_timeout_us))) {
         need_unlock_ = false;
@@ -371,13 +371,13 @@ public:
 
   struct WLockGuard
   {
-    explicit WLockGuard(RWLock& lock): lock_(lock) { lock_.wrlock(); }
+    [[nodiscard]] explicit WLockGuard(RWLock& lock): lock_(lock) { lock_.wrlock(); }
     ~WLockGuard() { lock_.wrunlock(); }
     RWLock& lock_;
   };
   struct WLockGuardWithTimeout
   {
-    explicit WLockGuardWithTimeout(RWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
+    [[nodiscard]] explicit WLockGuardWithTimeout(RWLock &lock, const int64_t abs_timeout_us, int &ret): lock_(lock), need_unlock_(true)
     {
       if (OB_FAIL(lock_.wrlock(abs_timeout_us))) {
         need_unlock_ = false;
@@ -397,7 +397,7 @@ public:
   };
   struct WLockGuardWithRetry
   {
-    explicit WLockGuardWithRetry(RWLock &lock, const int64_t abs_timeout_us) : lock_(lock)
+    [[nodiscard]] explicit WLockGuardWithRetry(RWLock &lock, const int64_t abs_timeout_us) : lock_(lock)
     {
       lock_.wrlock_with_retry(abs_timeout_us);
     }

deps/oblib/src/lib/lock/threadmutex.h

@@ -52,7 +52,7 @@ protected:
 class ThreadGuard
 {
 public:
-  ThreadGuard(ThreadMutex *mutex)
+  [[nodiscard]] ThreadGuard(ThreadMutex *mutex)
   {
     mutex_ = NULL;
     if (mutex) {