Reduce copies of LockInfo (#5172)

Summary:
The LockInfo struct is not easy to copy because it contains std::vector. Reduce copies by using move constructor and `unordered_map::emplace`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5172

Differential Revision: D14882053

Pulled By: lth

fbshipit-source-id: 93999ec6ab1a5841fb5115abb764b6c1831a6de1

utilities/transactions/transaction_base.cc

@@ -587,7 +587,7 @@ void TransactionBaseImpl::TrackKey(TransactionKeyMap* key_map, uint32_t cfh_id,
   auto& cf_key_map = (*key_map)[cfh_id];
   auto iter = cf_key_map.find(key);
   if (iter == cf_key_map.end()) {
-    auto result = cf_key_map.insert({key, TransactionKeyMapInfo(seq)});
+    auto result = cf_key_map.emplace(key, TransactionKeyMapInfo(seq));
     iter = result.first;
   } else if (seq < iter->second.seq) {
     // Now tracking this key with an earlier sequence number

utilities/transactions/transaction_lock_mgr.cc

@@ -311,14 +311,14 @@ Status TransactionLockMgr::TryLock(PessimisticTransaction* txn,
   int64_t timeout = txn->GetLockTimeout();
 
   return AcquireWithTimeout(txn, lock_map, stripe, column_family_id, key, env,
-                            timeout, lock_info);
+                            timeout, std::move(lock_info));
 }
 
 // Helper function for TryLock().
 Status TransactionLockMgr::AcquireWithTimeout(
     PessimisticTransaction* txn, LockMap* lock_map, LockMapStripe* stripe,
     uint32_t column_family_id, const std::string& key, Env* env,
-    int64_t timeout, const LockInfo& lock_info) {
+    int64_t timeout, LockInfo&& lock_info) {
   Status result;
   uint64_t end_time = 0;
 
@@ -342,7 +342,7 @@ Status TransactionLockMgr::AcquireWithTimeout(
   // Acquire lock if we are able to
   uint64_t expire_time_hint = 0;
   autovector<TransactionID> wait_ids;
-  result = AcquireLocked(lock_map, stripe, key, env, lock_info,
+  result = AcquireLocked(lock_map, stripe, key, env, std::move(lock_info),
                          &expire_time_hint, &wait_ids);
 
   if (!result.ok() && timeout != 0) {
@@ -407,7 +407,7 @@ Status TransactionLockMgr::AcquireWithTimeout(
       }
 
       if (result.ok() || result.IsTimedOut()) {
-        result = AcquireLocked(lock_map, stripe, key, env, lock_info,
+        result = AcquireLocked(lock_map, stripe, key, env, std::move(lock_info),
                                &expire_time_hint, &wait_ids);
       }
     } while (!result.ok() && !timed_out);
@@ -526,7 +526,7 @@ bool TransactionLockMgr::IncrementWaiters(
 Status TransactionLockMgr::AcquireLocked(LockMap* lock_map,
                                          LockMapStripe* stripe,
                                          const std::string& key, Env* env,
-                                         const LockInfo& txn_lock_info,
+                                         LockInfo&& txn_lock_info,
                                          uint64_t* expire_time,
                                          autovector<TransactionID>* txn_ids) {
   assert(txn_lock_info.txn_ids.size() == 1);
@@ -578,7 +578,7 @@ Status TransactionLockMgr::AcquireLocked(LockMap* lock_map,
       result = Status::Busy(Status::SubCode::kLockLimit);
     } else {
       // acquire lock
-      stripe->keys.insert({key, txn_lock_info});
+      stripe->keys.emplace(key, std::move(txn_lock_info));
 
       // Maintain lock count if there is a limit on the number of locks
       if (max_num_locks_) {

utilities/transactions/transaction_lock_mgr.h

@@ -130,11 +130,11 @@ class TransactionLockMgr {
   Status AcquireWithTimeout(PessimisticTransaction* txn, LockMap* lock_map,
                             LockMapStripe* stripe, uint32_t column_family_id,
                             const std::string& key, Env* env, int64_t timeout,
-                            const LockInfo& lock_info);
+                            LockInfo&& lock_info);
 
   Status AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
                        const std::string& key, Env* env,
-                       const LockInfo& lock_info, uint64_t* wait_time,
+                       LockInfo&& lock_info, uint64_t* wait_time,
                        autovector<TransactionID>* txn_ids);
 
   void UnLockKey(const PessimisticTransaction* txn, const std::string& key,