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Remove ifdef for try_emplace after upgrading to c++17 (#9932) 

Summary:
Test plan
make check

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9932

Reviewed By: ajkr

Differential Revision: D36085404

Pulled By: riversand963

fbshipit-source-id: 2ece14ca0e2e4c1288339ff79e7e126b76eaf786
This commit is contained in:
Yanqin Jin 2022-05-02 19:39:24 -07:00 committed by Facebook GitHub Bot
parent cda34dd64a
commit 2b5df21e95
1 changed files with 0 additions and 13 deletions
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13
utilities/transactions/lock/point/point_lock_tracker.cc
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@ -44,25 +44,12 @@ class TrackedKeysIterator : public LockTracker::KeyIterator {
void PointLockTracker::Track(const PointLockRequest& r) { void PointLockTracker::Track(const PointLockRequest& r) {
auto& keys = tracked_keys_[r.column_family_id]; auto& keys = tracked_keys_[r.column_family_id];
#ifdef __cpp_lib_unordered_map_try_emplace
// use c++17's try_emplace if available, to avoid rehashing the key
// in case it is not already in the map
auto result = keys.try_emplace(r.key, r.seq); auto result = keys.try_emplace(r.key, r.seq);
auto it = result.first; auto it = result.first;
if (!result.second && r.seq < it->second.seq) { if (!result.second && r.seq < it->second.seq) {
// Now tracking this key with an earlier sequence number // Now tracking this key with an earlier sequence number
it->second.seq = r.seq; it->second.seq = r.seq;
} }
#else
auto it = keys.find(r.key);
if (it == keys.end()) {
auto result = keys.emplace(r.key, TrackedKeyInfo(r.seq));
it = result.first;
} else if (r.seq < it->second.seq) {
// Now tracking this key with an earlier sequence number
it->second.seq = r.seq;
}
#endif
// else we do not update the seq. The smaller the tracked seq, the stronger it // else we do not update the seq. The smaller the tracked seq, the stronger it
// the guarantee since it implies from the seq onward there has not been a // the guarantee since it implies from the seq onward there has not been a
// concurrent update to the key. So we update the seq if it implies stronger // concurrent update to the key. So we update the seq if it implies stronger