perf: convert comparator functors to static constexpr (#5687)

libtransmission/peer-mgr.cc

@@ -1235,7 +1235,7 @@ namespace get_peers_helpers
 {
 
 /* better goes first */
-struct CompareAtomsByUsefulness
+constexpr struct
 {
     [[nodiscard]] constexpr static int compare(peer_atom const& a, peer_atom const& b) noexcept // <=>
     {
@@ -1266,7 +1266,7 @@ struct CompareAtomsByUsefulness
     {
         return compare(*a, *b) < 0;
     }
-};
+} CompareAtomsByUsefulness{};
 
 [[nodiscard]] bool isAtomInteresting(tr_torrent const* tor, peer_atom const& atom)
 {
@@ -1332,7 +1332,7 @@ std::vector<tr_pex> tr_peerMgrGetPeers(tr_torrent const* tor, uint8_t address_ty
         }
     }
 
-    std::sort(std::begin(atoms), std::end(atoms), CompareAtomsByUsefulness{});
+    std::sort(std::begin(atoms), std::end(atoms), CompareAtomsByUsefulness);
 
     // add the first N of them into our return list
 
@@ -2015,7 +2015,7 @@ void closePeer(tr_peer* peer)
     peer->swarm->removePeer(peer);
 }
 
-struct ComparePeerByActivity
+constexpr struct
 {
     [[nodiscard]] constexpr static int compare(tr_peer const* a, tr_peer const* b) // <=>
     {
@@ -2043,7 +2043,7 @@ struct ComparePeerByActivity
     {
         return compare(a, b) < 0;
     }
-};
+} ComparePeerByActivity{};
 
 [[nodiscard]] auto getPeersToClose(tr_swarm const* const swarm, time_t const now_sec)
 {
@@ -2081,7 +2081,7 @@ void enforceSwarmPeerLimit(tr_swarm* swarm, size_t max)
 
     // close all but the `max` most active
     auto peers = swarm->peers;
-    std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity{});
+    std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity);
     std::for_each(std::begin(peers) + max, std::end(peers), closePeer);
 }
 
@@ -2105,7 +2105,7 @@ void enforceSessionPeerLimit(tr_session* session)
     TR_ASSERT(tr_peerMsgs::size() == std::size(peers));
     if (std::size(peers) > max)
     {
-        std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity{});
+        std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity);
         std::for_each(std::begin(peers) + max, std::end(peers), closePeer);
     }
 }

libtransmission/rpcimpl.cc

@@ -197,18 +197,18 @@ char const* queueMoveBottom(tr_session* session, tr_variant* args_in, tr_variant
     return nullptr;
 }
 
-struct CompareTorrentByQueuePosition
+constexpr struct
 {
     constexpr bool operator()(tr_torrent const* a, tr_torrent const* b) const
     {
         return a->queuePosition < b->queuePosition;
     }
-};
+} CompareTorrentByQueuePosition{};
 
 char const* torrentStart(tr_session* session, tr_variant* args_in, tr_variant* /*args_out*/, tr_rpc_idle_data* /*idle_data*/)
 {
     auto torrents = getTorrents(session, args_in);
-    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         if (!tor->is_running())
@@ -224,7 +224,7 @@ char const* torrentStart(tr_session* session, tr_variant* args_in, tr_variant* /
 char const* torrentStartNow(tr_session* session, tr_variant* args_in, tr_variant* /*args_out*/, tr_rpc_idle_data* /*idle_data*/)
 {
     auto torrents = getTorrents(session, args_in);
-    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         if (!tor->is_running())

libtransmission/torrent.cc

@@ -546,13 +546,13 @@ namespace
 {
 namespace queue_helpers
 {
-struct CompareTorrentByQueuePosition
+constexpr struct
 {
     constexpr bool operator()(tr_torrent const* a, tr_torrent const* b) const noexcept
     {
         return a->queuePosition < b->queuePosition;
     }
-};
+} CompareTorrentByQueuePosition{};
 
 #ifdef TR_ENABLE_ASSERTS
 bool queueIsSequenced(tr_session const* session)
@@ -622,7 +622,7 @@ void tr_torrentsQueueMoveTop(tr_torrent* const* torrents_in, size_t torrent_coun
     using namespace queue_helpers;
 
     auto torrents = std::vector<tr_torrent*>(torrents_in, torrents_in + torrent_count);
-    std::sort(std::rbegin(torrents), std::rend(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::rbegin(torrents), std::rend(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         tr_torrentSetQueuePosition(tor, 0);
@@ -634,7 +634,7 @@ void tr_torrentsQueueMoveUp(tr_torrent* const* torrents_in, size_t torrent_count
     using namespace queue_helpers;
 
     auto torrents = std::vector<tr_torrent*>(torrents_in, torrents_in + torrent_count);
-    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         if (tor->queuePosition > 0)
@@ -649,7 +649,7 @@ void tr_torrentsQueueMoveDown(tr_torrent* const* torrents_in, size_t torrent_cou
     using namespace queue_helpers;
 
     auto torrents = std::vector<tr_torrent*>(torrents_in, torrents_in + torrent_count);
-    std::sort(std::rbegin(torrents), std::rend(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::rbegin(torrents), std::rend(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         if (tor->queuePosition < UINT_MAX)
@@ -664,7 +664,7 @@ void tr_torrentsQueueMoveBottom(tr_torrent* const* torrents_in, size_t torrent_c
     using namespace queue_helpers;
 
     auto torrents = std::vector<tr_torrent*>(torrents_in, torrents_in + torrent_count);
-    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition{});
+    std::sort(std::begin(torrents), std::end(torrents), CompareTorrentByQueuePosition);
     for (auto* tor : torrents)
     {
         tr_torrentSetQueuePosition(tor, UINT_MAX);

libtransmission/torrents.cc

@@ -17,7 +17,7 @@
 namespace
 {
 
-struct CompareTorrentByHash
+constexpr struct
 {
     bool operator()(tr_sha1_digest_t const& a, tr_sha1_digest_t const& b) const
     {
@@ -38,7 +38,7 @@ struct CompareTorrentByHash
     {
         return (*this)(a, b->info_hash());
     }
-};
+} CompareTorrentByHash{};
 
 } // namespace
 
@@ -50,13 +50,13 @@ tr_torrent* tr_torrents::get(std::string_view magnet_link)
 
 tr_torrent* tr_torrents::get(tr_sha1_digest_t const& hash)
 {
-    auto [begin, end] = std::equal_range(std::begin(by_hash_), std::end(by_hash_), hash, CompareTorrentByHash{});
+    auto [begin, end] = std::equal_range(std::begin(by_hash_), std::end(by_hash_), hash, CompareTorrentByHash);
     return begin == end ? nullptr : *begin;
 }
 
 tr_torrent const* tr_torrents::get(tr_sha1_digest_t const& hash) const
 {
-    auto [begin, end] = std::equal_range(std::cbegin(by_hash_), std::cend(by_hash_), hash, CompareTorrentByHash{});
+    auto [begin, end] = std::equal_range(std::cbegin(by_hash_), std::cend(by_hash_), hash, CompareTorrentByHash);
     return begin == end ? nullptr : *begin;
 }
 
@@ -64,7 +64,7 @@ tr_torrent_id_t tr_torrents::add(tr_torrent* tor)
 {
     auto const id = static_cast<tr_torrent_id_t>(std::size(by_id_));
     by_id_.push_back(tor);
-    by_hash_.insert(std::lower_bound(std::begin(by_hash_), std::end(by_hash_), tor, CompareTorrentByHash{}), tor);
+    by_hash_.insert(std::lower_bound(std::begin(by_hash_), std::end(by_hash_), tor, CompareTorrentByHash), tor);
     return id;
 }
 
@@ -74,7 +74,7 @@ void tr_torrents::remove(tr_torrent const* tor, time_t current_time)
     TR_ASSERT(get(tor->id()) == tor);
 
     by_id_[tor->id()] = nullptr;
-    auto const [begin, end] = std::equal_range(std::begin(by_hash_), std::end(by_hash_), tor, CompareTorrentByHash{});
+    auto const [begin, end] = std::equal_range(std::begin(by_hash_), std::end(by_hash_), tor, CompareTorrentByHash);
     by_hash_.erase(begin, end);
     removed_.emplace_back(tor->id(), current_time);
 }