From d9f70f51dcdf20db8473c1b688a40ebae19e2e12 Mon Sep 17 00:00:00 2001
From: Charles Kerr <charles@charleskerr.com>
Date: Tue, 31 May 2022 10:53:46 -0500
Subject: [PATCH] perf: avoid std::string temporaries in sessionLoadTorrent()
 (#3165)

---
 libtransmission/session.cc      |  7 ++-----
 libtransmission/torrent-ctor.cc | 11 ++++++++---
 libtransmission/torrent.h       |  4 ++--
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/libtransmission/session.cc b/libtransmission/session.cc
index 633e65a1a..42610c60a 100644
--- a/libtransmission/session.cc
+++ b/libtransmission/session.cc
@@ -2045,14 +2045,11 @@ static void sessionLoadTorrents(struct sessionLoadTorrentsData* const data)
             auto const path = tr_pathbuf{ dirname_sv, "/"sv, name };
 
             // is a magnet link?
-            if (!tr_ctorSetMetainfoFromFile(data->ctor, std::string{ path }, nullptr))
+            if (!tr_ctorSetMetainfoFromFile(data->ctor, path.sv(), nullptr))
             {
                 if (auto buf = std::vector<char>{}; tr_loadFile(path, buf))
                 {
-                    tr_ctorSetMetainfoFromMagnetLink(
-                        data->ctor,
-                        std::string{ std::data(buf), std::size(buf) }.c_str(),
-                        nullptr);
+                    tr_ctorSetMetainfoFromMagnetLink(data->ctor, std::string_view{ std::data(buf), std::size(buf) }, nullptr);
                 }
             }
 
diff --git a/libtransmission/torrent-ctor.cc b/libtransmission/torrent-ctor.cc
index 9ef029888..4566f6808 100644
--- a/libtransmission/torrent-ctor.cc
+++ b/libtransmission/torrent-ctor.cc
@@ -66,7 +66,7 @@ struct tr_ctor
 ****
 ***/
 
-bool tr_ctorSetMetainfoFromFile(tr_ctor* ctor, std::string const& filename, tr_error** error)
+bool tr_ctorSetMetainfoFromFile(tr_ctor* ctor, std::string_view filename, tr_error** error)
 {
     if (std::empty(filename))
     {
@@ -97,11 +97,16 @@ bool tr_ctorSetMetainfo(tr_ctor* ctor, char const* metainfo, size_t len, tr_erro
     return ctor->metainfo.parseBenc(contents_sv, error);
 }
 
-bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, char const* magnet_link, tr_error** error)
+bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, std::string_view magnet_link, tr_error** error)
 {
     ctor->torrent_filename.clear();
     ctor->metainfo = {};
-    return ctor->metainfo.parseMagnet(magnet_link != nullptr ? magnet_link : "", error);
+    return ctor->metainfo.parseMagnet(magnet_link, error);
+}
+
+bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, char const* magnet_link, tr_error** error)
+{
+    return tr_ctorSetMetainfoFromMagnetLink(ctor, std::string_view{ magnet_link != nullptr ? magnet_link : "" }, error);
 }
 
 char const* tr_ctorGetSourceFile(tr_ctor const* ctor)
diff --git a/libtransmission/torrent.h b/libtransmission/torrent.h
index 19ddc07f4..cf7eeeec3 100644
--- a/libtransmission/torrent.h
+++ b/libtransmission/torrent.h
@@ -774,8 +774,8 @@ tr_peer_id_t const& tr_torrentGetPeerId(tr_torrent* tor);
 
 tr_torrent_metainfo tr_ctorStealMetainfo(tr_ctor* ctor);
 
-bool tr_ctorSetMetainfoFromFile(tr_ctor* ctor, std::string const& filename, tr_error** error);
-bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, std::string const& filename, tr_error** error);
+bool tr_ctorSetMetainfoFromFile(tr_ctor* ctor, std::string_view filename, tr_error** error);
+bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, std::string_view filename, tr_error** error);
 void tr_ctorSetLabels(tr_ctor* ctor, tr_quark const* labels, size_t n_labels);
 tr_torrent::labels_t const& tr_ctorGetLabels(tr_ctor const* ctor);